MYST regulates DNA repair and forms a NuA4-like complex in the malaria parasite Plasmodium falciparum

Histone lysine acetyltransferase MYST-associated NuA4 complex is conserved from yeast to humans and plays key roles in cell cycle regulation, gene transcription, and DNA replication/repair. Here, we identified a Plasmodium falciparum MYST-associated complex, PfNuA4, which contains 11 of the 13 conserved NuA4 subunits. Reciprocal pulldowns using PfEAF2, a shared component between the NuA4 and SWR1 complexes, not only confirmed the PfNuA4 complex but also identified the PfSWR1 complex, a histone remodeling complex, although their identities are low compared to the homologs in yeast or humans. Notably, both H2A.Z/H2B.Z were associated with the PfSWR1 complex, indicating that this complex is involved in the deposition of H2A.Z/H2B.Z, the variant histone pair that is enriched in the activated promoters. Overexpression of PfMYST resulted in earlier expression of genes involved in cell cycle regulation, DNA replication, and merozoite invasion, and upregulation of the genes related to antigenic variation and DNA repair. Consistently, PfMYST overexpression led to high basal phosphorylated PfH2A (γ-PfH2A), the mark of DNA double-strand breaks, and conferred protection against genotoxic agent methyl methanesulfonate (MMS), X-rays, and artemisinin, the first-line antimalarial drug. In contrast, the knockdown of PfMYST caused a delayed parasite recovery upon MMS treatment. MMS induced the gradual disappearance of PfMYST in the cytoplasm and concomitant accumulation of PfMYST in the nucleus, suggesting cytoplasm-nucleus shuttling of PfMYST. Meanwhile, PfMYST colocalized with the γ-PfH2A, indicating PfMYST was recruited to the DNA damage sites. Collectively, PfMYST plays critical roles in cell cycle regulation, gene transcription, and DNA replication/DNA repair in this low-branching parasitic protist.IMPORTANCEUnderstanding gene regulation and DNA repair in malaria parasites is critical for identifying targets for antimalarials. This study found PfNuA4, a PfMYST-associated, histone modifier complex, and PfSWR1, a chromatin remodeling complex in malaria parasite Plasmodium falciparum. These complexes are divergent due to the low identities compared to their homologs from yeast and humans. Furthermore, overexpression of PfMYST resulted in substantial transcriptomic changes, indicating that PfMYST is involved in regulating the cell cycle, antigenic variation, and DNA replication/repair. Consistently, PfMYST was found to protect against DNA damage caused by the genotoxic agent methyl methanesulfonate, X-rays, and artemisinin, the first-line antimalarial drug. Additionally, DNA damage led to the relocation of cytoplasmic PfMYST to the nucleus and colocalization of PfMYST with γ-PfH2A, the mark of DNA damage. In summary, this study demonstrated that the PfMYST complex has critical functions in regulating cell cycle, antigenic variation, and DNA replication/DNA repair in P. falciparum.

Evaluation of different types of adjuvants in a malaria transmission-blocking vaccine

Adjuvants are critical components for vaccines, which enhance the strength and longevity of the antibody response and influence the types of immune response. Limited research has been conducted on the immunogenicity and protective efficacy of various adjuvants in malaria transmission-blocking vaccines (TBVs). In this study, we formulated a promising TBV candidate antigen, the P. berghei ookinete surface antigen PSOP25, with different types of adjuvants, including the TLR4 agonist monophosphoryl lipid A (MPLA), the TLR9 agonist cytosine phosphoguanosine oligodeoxynucleotides (CpG ODN 1826) (CpG), a saponin adjuvant QS-21, aluminum hydroxide (Alum), and two combination adjuvants MPLA + QS-21 and QS-21 + CpG. We demonstrated that adjuvanted vaccines results in elevated elicited antibody levels, increased proliferation of plasma cells, and efficient formation of germinal centers (GCs), leading to enhanced long-term protective immune responses. Furthermore, CpG group exhibited the most potent inhibition of ookinete formation and transmission-blocking activity. We found that the rPSOP25 with CpG adjuvant was more effective than MPLA, QS-21, MPLA + QS-21, QS-21 + CpG adjuvants in dendritic cells (DCs) activation and differentiation. Additionally, the CpG adjuvant elicited more rubust immune memory response than Alum adjuvant. CpG and QS-21 adjuvants could activate the Th1 response and promote the secretion of IFN-γ and TNF-α. PSOP25 induced a higher number of Tfh cells in splenocytes when combined with MPLA, CpG, and QS-21 + CpG; and there was no increase in these cell populations when PSOP25 was administered with Alum. In conclusion, CpG may confer enhanced efficacy for the rPSOP25 vaccine, as evidenced by the ability of the elicited antisera to induce protective immune responses and improved transmission-blocking activity.

Modelling spatiotemporal variation in under-five malaria risk in Ghana in 2016-2021

BACKGROUND

Ghana is among the top 10 highest malaria burden countries, with about 20,000 children dying annually, 25% of which were under five years. This study aimed to produce interactive web-based disease spatial maps and identify the high-burden malaria districts in Ghana.

METHODS

The study used 2016-2021 data extracted from the routine health service nationally representative and comprehensive District Health Information Management System II (DHIMS2) implemented by the Ghana Health Service. Bayesian geospatial modelling and interactive web-based spatial disease mapping methods were employed to quantify spatial variations and clustering in malaria risk across 260 districts. For each district, the study simultaneously mapped the observed malaria counts, district name, standardized incidence rate, and predicted relative risk and their associated standard errors using interactive web-based visualization methods.

RESULTS

A total of 32,659,240 malaria cases were reported among children < 5 years from 2016 to 2021. For every 10% increase in the number of children, malaria risk increased by 0.039 (log-mean 0.95, 95% credible interval = - 13.82-15.73) and for every 10% increase in the number of males, malaria risk decreased by 0.075, albeit not statistically significant (log-mean - 1.82, 95% credible interval = - 16.59-12.95). The study found substantial spatial and temporal differences in malaria risk across the 260 districts. The predicted national relative risk was 1.25 (95% credible interval = 1.23, 1.27). The malaria risk is relatively the same over the entire year. However, a slightly higher relative risk was recorded in 2019 while in 2021, residing in Keta, Abuakwa South, Jomoro, Ahafo Ano South East, Tain, Nanumba North, and Tatale Sanguli districts was associated with the highest malaria risk ranging from a relative risk of 3.00 to 4.83. The district-level spatial patterns of malaria risks changed over time.

CONCLUSION

This study identified high malaria risk districts in Ghana where urgent and targeted control efforts are required. Noticeable changes were also observed in malaria risk for certain districts over some periods in the study. The findings provide an effective, actionable tool to arm policymakers and programme managers in their efforts to reduce malaria risk and its associated morbidity and mortality in line with the Sustainable Development Goals (SDG) 3.2 for limited public health resource settings, where universal intervention across all districts is practically impossible.

Deteriorated bone microarchitecture caused by sympathetic overstimulation in pheochromocytoma and paraganglioma

PURPOSE

Despite the potentially destructive effect of sympathetic activity on bone metabolism, its impact on bone microarchitecture, a key determinant of bone quality, has not been thoroughly investigated. This study aims to evaluate the impact of sympathetic activity on bone microarchitecture and bone strength in patients with pheochromocytoma and paraganglioma (PPGL).

METHODS

A cross-sectional study was conducted in 38 PPGL patients (15 males and 23 females). Bone turnover markers serum procollagen type 1 N-terminal propeptide (P1NP) and β-carboxy-terminal crosslinked telopeptide of type 1 collagen (β-CTX) were measured. 24-h urinary adrenaline (24hUE) and 24-h urinary norepinephrine levels (24hUNE) were measured to indicate sympathetic activity. High-resolution peripheral quantitative computed tomography (HR-pQCT) was conducted to evaluate bone microarchitecture in PPGL patients and 76 age-, sex-matched healthy controls (30 males and 46 females). Areal bone mineral density (aBMD) was measured by dual-energy X-ray absorptiometry (DXA) simultaneously.

RESULTS

PPGL patients had a higher level of β-CTX. HR-pQCT assessment revealed that PPGL patients had notably thinner and more sparse trabecular bone (decreased trabecular number and thickness with increased trabecular separation), significantly decreased volume BMD (vBMD), and bone strength at both the radius and tibia compared with healthy controls. The deterioration of Tt.vBMD, Tb.Sp, and Tb.1/N.SD was more pronounced in postmenopausal patients compared with the premenopausal subjects. Moreover, subjects in the highest 24hUNE quartile (Q4) showed markedly lower Tb.N and higher Tb.Sp and Tb.1/N.SD at the tibia than those in the lowest quartile (Q1). Age-related bone loss was also exacerbated in PPGL patients to a certain extent.

CONCLUSIONS

PPGL patients had significantly deteriorated bone microarchitecture and strength, especially in the trabecular bone, with an increased bone resorption rate. Our findings provide clinical evidence that sympathetic overstimulation may serve as a secondary cause of osteoporosis, especially in subjects with increased sympathetic activity.

Absence of association between Pfnfs1 mutation and in vitro susceptibility to lumefantrine in Plasmodium falciparum

Artemether-lumefantrine (AL) is the most widely used antimalarial drug for treating uncomplicated falciparum malaria. This study evaluated whether the K65Q mutation in the Plasmodium falciparum cysteine desulfurase IscS (Pfnfs1) gene was associated with alternated susceptibility to lumefantrine using clinical parasite samples from Ghana and the China-Myanmar border area. Parasite isolates from the China-Myanmar border had significantly higher IC50 values to lumefantrine than parasites from Ghana. In addition, the K65 allele was significantly more prevalent in the Ghanaian parasites (34.5%) than in the China-Myanmar border samples (6.8%). However, no difference was observed in the lumefantrine IC50 value between the Pfnfs1 reference K65 allele and the non reference 65Q allele in parasites from the two regions. These data suggest that the Pfnfs1 K65Q mutation may not be a reliable marker for reduced susceptibility to lumefantrine.

Effect of textile colour on vector mosquito host selection: a simulated field study in Mali, West Africa

BACKGROUND

The effect of clothing colour on the biting rates of different vector mosquito species is not well understood. Studies under tropical field conditions are lacking. This study aimed to determine the influence of clothing colours on mosquito biting rates in rural and suburban settings in West Africa.

METHODS

We performed a simulated field study in a suburban and a rural site in Mali using Mosquito-Magnet traps utilizing CO2 and other attractants, which were covered with black, white, and black/white striped textile sheets covers. These targets operated continuously for 10 consecutive days with bright nights (around full moon) and 10 consecutive days with dark nights (around new moon). Trapped mosquitoes were collected and catch rates counted hourly. Mosquitoes were morphologically identified to the species complex level (Anopheles gambiae s.l. and Culex pipiens s.l.) or species level (Aedes aegypti). A subset of Anopheles specimens were further identified by molecular methods.

RESULTS

Under bright-night conditions, An. gambiae s.l. was significantly more attracted to black targets than to white and striped targets; during dark nights, no target preference was noted. During bright nights, Cx. pipiens s.l. was significantly more attracted to black and striped targets than to white targets; a similar trend was noted during dark nights (not significant). For day-active Ae. aegypti, striped targets were more attractive than the other targets and black were more attractive than white targets.

CONCLUSIONS

The study firstly demonstrated that under field conditions in Mali, West Africa, mosquito catch rates were influenced by different clothing colours, depending on mosquito species and light conditions. Overall, light colours were least attractive to host-seeking mosquitoes. Using white or other light-coloured clothing can potentially reduce bite exposure and risk of disease transmission in endemic tropical regions.

Multifunctional scaffolds for biomedical applications: Crafting versatile solutions with polycaprolactone enriched by graphene oxide

The pressing need for multifunctional materials in medical settings encompasses a wide array of scenarios, necessitating specific tissue functionalities. A critical challenge is the occurrence of biofouling, particularly by contamination in surgical environments, a common cause of scaffolds impairment. Beyond the imperative to avoid infections, it is also essential to integrate scaffolds with living cells to allow for tissue regeneration, mediated by cell attachment. Here, we focus on the development of a versatile material for medical applications, driven by the diverse time-definite events after scaffold implantation. We investigate the potential of incorporating graphene oxide (GO) into polycaprolactone (PCL) and create a composite for 3D printing a scaffold with time-controlled antibacterial and anti-adhesive growth properties. Indeed, the as-produced PCL-GO scaffold displays a local hydrophobic effect, which is translated into a limitation of biological entities-attachment, including a diminished adhesion of bacteriophages and a reduction of E. coli and S. aureus adhesion of ∼81% and ∼69%, respectively. Moreover, the ability to 3D print PCL-GO scaffolds with different heights enables control over cell distribution and attachment, a feature that can be also exploited for cellular confinement, i.e., for microfluidics or wound healing applications. With time, the surface wettability increases, and the scaffold can be populated by cells. Finally, the presence of GO allows for the use of infrared light for the sterilization of scaffolds and the disruption of any bacteria cell that might adhere to the more hydrophilic surface. Overall, our results showcase the potential of PCL-GO as a versatile material for medical applications.

Naturally Acquired Transmission-Blocking Immunity Against Different Strains of Plasmodium vivax in a Malaria-Endemic Area in Thailand

BACKGROUND

Human immunity triggered by natural malaria infections impedes parasite transmission from humans to mosquitoes, leading to interest in transmission-blocking vaccines. However, immunity characteristics, especially strain specificity, remain largely unexplored. We investigated naturally acquired transmission-blocking immunity (TBI) against Plasmodium vivax, a major malaria parasite.

METHODS

Using the direct membrane-feeding assay, we assessed TBI in plasma samples and examined the role of antibodies by removing immunoglobulins through protein G/L adsorption before mosquito feeding. Strain specificity was evaluated by conducting a direct membrane-feeding assay with plasma exchange.

RESULTS

Blood samples from 47 patients with P vivax were evaluated, with 37 plasma samples successfully infecting mosquitoes. Among these, 26 showed inhibition before immunoglobulin depletion. Despite substantial immunoglobulin removal, 4 samples still exhibited notable inhibition, while 22 had reduced blocking activity. Testing against heterologous strains revealed some plasma samples with broad TBI and others with strain-specific TBI.

CONCLUSIONS

Our findings indicate that naturally acquired TBI is mainly mediated by antibodies, with possible contributions from other serum factors. The transmission-blocking activity of plasma samples varied by the tested parasite strain, suggesting single polymorphic or multiple targets for naturally acquired TBI. These observations improve understanding of immunity against P vivax and hold implications for transmission-blocking vaccine development.

Effectiveness of artemether-lumefantrine for treating uncomplicated malaria in low- and high-transmission areas of Ghana

BACKGROUND

Artemisinin-based combination therapy (ACT) has been effective in the supervised treatment of uncomplicated malaria in Ghana. Since ACT usage is primarily unsupervised, this study aimed to determine the effectiveness of artemether-lumefantrine (AL) for treating malaria patients in two transmission settings in Ghana.

METHODS

Eighty-four individuals with uncomplicated Plasmodium falciparum malaria were recruited from Lekma Hospital (LH) in Accra (low-transmission area; N = 28), southern Ghana, and King's Medical Centre (KMC) in Kumbungu (high-transmission area; N = 56), northern Ghana. Participants were followed up for 28 days after unsupervised treatment with AL. The presence of asexual parasites was determined by microscopic examination of Giemsa-stained blood smears. Plasmodium species identification was confirmed using species-specific primers targeting the 18S rRNA gene. Parasite recrudescence or reinfection was determined by genotyping the Pfmsp 1 and Pfmsp 2 genes.

RESULTS

After AL treatment, 3.6% (2/56) of the patients from KMC were parasitaemic on day 3 compared to none from the LH patients. One patient from KMC with delayed parasite clearance on day 3 remained parasite-positive by microscopy on day 7 but was parasite-free by day 14. While none of the patients from LH experienced parasite recurrence during the 28-day follow-up, three and two patients from KMC had recurrent parasitaemia on days 21 and 28, respectively. Percentage reduction in parasite densities from day 1, 2, and 3 for participants from the KMC was 63.2%, 89.5%, and 84.5%. Parasite densities for participants from the LH reduced from 98.2%, 99.8% on day 1, and 2 to 100% on day 3. The 28-day cumulative incidence rate of treatment failure for KMC was 12.8% (95% confidence interval: 1.9-23.7%), while the per-protocol effectiveness of AL in KMC was 89.47%. All recurrent cases were assigned to recrudescence after parasite genotyping by Pfmsp 1 and Pfmsp 2.

CONCLUSION

While AL is efficacious in treating uncomplicated malaria in Ghana, when taken under unsupervised conditions, it showed an 89.4% PCR-corrected cure rate in northern Ghana, which is slightly below the WHO-defined threshold.

Effect of primaquine dose on the risk of recurrence in patients with uncomplicated Plasmodium vivax: a systematic review and individual patient data meta-analysis

BACKGROUND

Primaquine is used to eliminate Plasmodium vivax hypnozoites, but its optimal dosing regimen remains unclear. We undertook a systematic review and individual patient data meta-analysis to investigate the efficacy and tolerability of different primaquine dosing regimens to prevent P vivax recurrence.

METHODS

For this systematic review and individual patient data meta-analysis, we searched MEDLINE, Web of Science, Embase, and Cochrane Central for prospective clinical studies of uncomplicated P vivax from endemic countries published between Jan 1, 2000, and June 8, 2023. We included studies if they had active follow-up of at least 28 days, and if they included a treatment group with daily primaquine given over multiple days, where primaquine was commenced within 7 days of schizontocidal treatment and was given alone or coadministered with chloroquine or one of four artemisinin-based combination therapies (ie, artemether-lumefantrine, artesunate-mefloquine, artesunate-amodiaquine, or dihydroartemisinin-piperaquine). We excluded studies if they were on prevention, prophylaxis, or patients with severe malaria, or if data were extracted retrospectively from medical records outside of a planned trial. For the meta-analysis, we contacted the investigators of eligible trials to request individual patient data and we then pooled data that were made available by Aug 23, 2021. We assessed the effects of total dose and duration of primaquine regimens on the rate of first P vivax recurrence between day 7 and day 180 by Cox's proportional hazards regression (efficacy analysis). The effect of primaquine daily dose on gastrointestinal symptoms on days 5-7 was assessed by modified Poisson regression (tolerability analysis). The study was registered with PROSPERO, CRD42019154470.

FINDINGS

Of 226 identified studies, 23 studies with patient-level data from 6879 patients from 16 countries were included in the efficacy analysis. At day 180, the risk of recurrence was 51·0% (95% CI 48·2-53·9) in 1470 patients treated without primaquine, 19·3% (16·9-21·9) in 2569 patients treated with a low total dose of primaquine (approximately 3·5 mg/kg), and 8·1% (7·0-9·4) in 2811 patients treated with a high total dose of primaquine (approximately 7 mg/kg), regardless of primaquine treatment duration. Compared with treatment without primaquine, the rate of P vivax recurrence was lower after treatment with low-dose primaquine (adjusted hazard ratio 0·21, 95% CI 0·17-0·27; p<0·0001) and high-dose primaquine (0·10, 0·08-0·12; p<0·0001). High-dose primaquine had greater efficacy than low-dose primaquine in regions with high and low relapse periodicity (ie, the time from initial infection to vivax relapse). 16 studies with patient-level data from 5609 patients from ten countries were included in the tolerability analysis. Gastrointestinal symptoms on days 5-7 were reported by 4·0% (95% CI 0·0-8·7) of 893 patients treated without primaquine, 6·2% (0·5-12·0) of 737 patients treated with a low daily dose of primaquine (approximately 0·25 mg/kg per day), 5·9% (1·8-10·1) of 1123 patients treated with an intermediate daily dose (approximately 0·5 mg/kg per day) and 10·9% (5·7-16·1) of 1178 patients treated with a high daily dose (approximately 1 mg/kg per day). 20 of 23 studies included in the efficacy analysis and 15 of 16 in the tolerability analysis had a low or unclear risk of bias.

INTERPRETATION

Increasing the total dose of primaquine from 3·5 mg/kg to 7 mg/kg can reduce P vivax recurrences by more than 50% in most endemic regions, with a small associated increase in gastrointestinal symptoms.

FUNDING

Australian National Health and Medical Research Council, Bill & Melinda Gates Foundation, and Medicines for Malaria Venture.

Functional characterization of a conserved membrane protein, Pbs54, involved in gamete fertilization in Plasmodium berghei

The successful completion of gamete fertilization is essential for malaria parasite transmission, and this process can be targeted by intervention strategies. In this study, we identified a conserved gene (PBANKA_0813300) in the rodent malaria parasite Plasmodium berghei, which encodes a protein of 54 kDa (designated as Pbs54). Localization studies indicated that Pbs54 is associated with the plasma membranes of gametes and ookinetes. Functional studies by gene disruption showed that the Δpbs54 parasites had no defect in asexual proliferation, gametocyte development, or gametogenesis. However, the interactions between male and female gametes were significantly decreased compared with wild-type parasites. The Δpbs54 lines did not show a further reduction in zygote and ookinete numbers during in vitro culture, indicating that the defects were probably restricted to gamete fertilization. Consistent with this finding, mosquitoes fed on Δpbs54-infected mice showed a 30.1% reduction in infection prevalence and a 74.7% reduction in oocyst intensity. Cross-fertilization assay indicated that both male and female gametes were impaired in the Δpbs54 parasites. To evaluate its transmission-blocking potential, we obtained polyclonal antibodies from mice immunized with the recombinant Pbs54 (rPbs54) protein. In vitro assays showed that anti-rPbs54 sera inhibited ookinete formation by 42.7%. Our experiments identified Pbs54 as a fertility factor required for mosquito transmission and a novel candidate for a malaria transmission-blocking vaccine.

Baseline susceptibility of Anopheles gambiae to clothianidin in northern Ghana

BACKGROUND

Clothianidin, an insecticide with a novel mode of action, has been deployed in the annual indoor residual spraying programme in northern Ghana since March 2021. To inform pragmatic management strategies and guide future studies, baseline data on local Anopheles gambiae sensu lato (s.l.) susceptibility to the clothianidin insecticide were collected in Kpalsogu, a village in the Northern region, Ghana.

METHODS

Phenotypic susceptibility of An. gambiae mosquitoes to clothianidin was assessed using the World Health Organization (WHO) insecticide resistance monitoring bioassay. The WHO cone bioassays were conducted on mud and cement walls sprayed with Sumishield 50 wettable granules (WG) (with clothianidin active ingredient). Daily mortalities were recorded for up to 7 days to observe for delayed mortalities. Polymerase chain reaction (PCR) technique was used to differentiate the sibling species of the An. gambiae complex and also for the detection of knock down resistance genes (kdr) and the insensitive acetylcholinesterase mutation (ace-1).

RESULTS

The WHO susceptibility bioassay revealed a delayed killing effect of clothianidin. Mosquitoes exposed to the cone bioassays for 5 min died 120 h after exposure. Slightly higher mortalities were observed in mosquitoes exposed to clothianidin-treated cement wall surfaces than mosquitoes exposed to mud wall surfaces. The kdr target-site mutation L1014F occurred at very high frequencies (0.89-0.94) across all vector species identified whereas the ace-1 mutation occurred at moderate levels (0.32-0.44). Anopheles gambiae sensu stricto was the most abundant species observed at 63%, whereas Anopheles arabiensis was the least observed at 9%.

CONCLUSIONS

Anopheles gambiae s.l. mosquitoes in northern Ghana were susceptible to clothianidin. They harboured kdr mutations at high frequencies. The ace-1 mutation occurred in moderation. The results of this study confirm that clothianidin is an effective active ingredient and should be utilized in malaria vector control interventions.

An imported malaria case with repeated episodes of neurological syndromes resulting from different Plasmodium species

BACKGROUND

Imported cerebral malaria (CM) cases in non-endemic areas are often misdiagnosed, which delays treatment. Post-malaria neurological syndrome (PMNS) after recovery from severe malaria can also complicate diagnosis.

CASE

We report an imported malaria case from West Africa with two sequential episodes with neurological syndromes within about a month. The first episode was diagnosed as CM with microscopy-positive Plasmodium falciparum infection. The second episode, occurring a month after the recovery from the first CM episode, was consistent with PMNS, since malaria parasites were not detected by microscopy in peripheral blood smears. However, this diagnosis was complicated by the detection of Plasmodium vivax in peripheral blood by PCR, suggesting a potential cause of the second episode by P. vivax.

CONCLUSION

This study suggests that PMNS often occurs after severe falciparum malaria. Concurrent P. vivax infection with pathogenic biomass being predominantly extravascular further complicates accurate diagnosis.

Relationship between the impacted mandibular third molar and adjacent second molar' external root resorption by cone-bean computed tomography analysis

BACKGROUND

The relationship between the impacted mandibular third molar (IMTM) and the external root resorption (ERR) of the mandibular second molar (MSM) was analysed with cone-beam computed tomography (CBCT). The risk factors affecting the ERR of the MSM were examined to provide a reference.

MATERIAL AND METHODS

A total of 327 patients (total: 578 teeth) admitted to the Affiliated Hospital of Yanbian University for IMTM extraction from January 2017 to December 2019 was chosen and divided according to gender and age. The correlation between the IMTM and ERR of MSM was analysed, including inclination angle, impaction direction and depth. The relationship of mandibular ascending ramus classification with ERR of MSM was also analysed. In addition, the correlation between the MTM impaction type and the severity of ERR was analysed.

RESULTS

The incidence of ERR of MSM in male patients was higher than in females (27.9% vs.17.6%, p = 0.018). The occurrence and the site of ERR showed statistical differences in the inclination angle [(≤20°, 3.6%) vs. (21°-40°, 27.1%) vs. (41°-60°, 27.6%) vs. (61°-80°, 25.6%) vs. (>80°, 31.7%), p <0.001], impaction direction [(Vertical, 1.1%) vs. (Mesial, 32.7%) vs. (Horizontal, 25.3%), p <0.001] and depth of MTM [(Low position, 38.6%) vs. (Median position, 32.0%) vs. (High position, 13.7%), p <0.001]. Also, there was a significant difference in the mandibular ascending ramus type [(Class I, 17.4%) vs. (Class II, 32.3%) vs. (Class III, 44.9%), p <0.001]. In addition, the severity of ERR showed statistical differences in the mesial (40.9%, p<0.05), lower impaction (54.5%, p<0.05) depth of MTM and type III of mandibular ascending ramus (63.6%, p<0.05).

CONCLUSIONS

The inclination angle, impaction direction, and depth of MTM were the influencing factors for the occurrence and site of ERR. Also, mandibular ascending ramus type was the impact fact. For MTM with mesioangular, lower impaction, and mandibular ascending ramus with type III, the ERR of the MSM was severer.

A dual-antigen malaria vaccine targeting Pb22 and Pbg37 was able to induce robust transmission-blocking activity

BACKGROUND

Despite years of effort to develop an effective vaccine against malaria infection, a vaccine that provides individuals with sufficient protection against malaria illness and death in endemic areas is not yet available. The development of transmission-blocking vaccines (TBVs) is a promising strategy for malaria control. A dual-antigen malaria vaccine targeting both pre- and post-fertilization antigens could effectively improve the transmission-blocking activity of vaccines against the sexual stages of the parasite.

METHODS

A chimeric recombinant protein Pb22-Pbg37 (Plasmodium berghei 22-P. berghei G37) composed of 19-218 amino acids (aa) of Pb22 and the N-terminal 26-88 aa of Pbg37 was designed and expressed in the Escherichia coli expression system. The antibody titers of the fusion (Pb22-Pbg37) and mixed (Pb22+Pbg37) antigens, as well as those of Pb22 and Pbg37 single antigens were evaluated by enzyme-linked immunosorbent assay. Immunofluorescence and western blot assays were performed to test the reactivity of the antisera with the native proteins in the parasite. The induction of transmission-blocking activity (TBA) by Pb22-Pbg37 and Pb22+Pbg37 were evaluated by in vitro gametocyte activation, gamete and exflagellation center formation, ookinete conversion, and in the direct mosquito feeding assay.

RESULTS

The Pb22-Pbg37 fusion protein was successfully expressed in vitro. Co-administration of Pb22 and Pbg37 as a fusion or mixed protein elicited comparable antibody responses in mice and resulted in responses to both antigens. Most importantly, both the mixed and fusion antigens induced antibodies with significantly higher levels of TBA than did each of the individual antigens when administered alone. In addition, the efficacy of vaccination with the Pb22-Pbg37 fusion protein was equivalent to that of vaccination with the mixed single antigens.

CONCLUSIONS

Dual-antigen vaccines, which expand/lengthen the period during which the transmission-blocking antibodies can act during sexual-stage development, can provide a promising higher transmission-reducing activity compared to single antigens.

Structures revealing mechanisms of resistance and collateral sensitivity of Plasmodium falciparum to proteasome inhibitors

The proteasome of the malaria parasite Plasmodium falciparum (Pf20S) is an advantageous drug target because its inhibition kills P. falciparum in multiple stages of its life cycle and synergizes with artemisinins. We recently developed a macrocyclic peptide, TDI-8304, that is highly selective for Pf20S over human proteasomes and is potent in vitro and in vivo against P. falciparum. A mutation in the Pf20S β6 subunit, A117D, confers resistance to TDI-8304, yet enhances both enzyme inhibition and anti-parasite activity of a tripeptide vinyl sulfone β2 inhibitor, WLW-vs. Here we present the high-resolution cryo-EM structures of Pf20S with TDI-8304, of human constitutive proteasome with TDI-8304, and of Pf20Sβ6A117D with WLW-vs that give insights into the species selectivity of TDI-8304, resistance to it, and the collateral sensitivity associated with resistance, including that TDI-8304 binds β2 and β5 in wild type Pf20S as well as WLW-vs binds β2 and β5 in Pf20Sβ6A117D. We further show that TDI-8304 kills P. falciparum as quickly as chloroquine and artemisinin and is active against P. cynomolgi at the liver stage. This increases interest in using these structures to facilitate the development of Pf20S inhibitors that target multiple proteasome subunits and limit the emergence of resistance.

[Risk factors of systemic allergic reactions caused by subcutaneous allergen immunotherapy]

Objective: To investigate the incidence and risk factors of systemic allergic reactions induced by subcutaneous immunotherapy (SCIT) in patients undergoing SCIT injections in Peking Union Medical College Hospital (PUMCH). Methods: This is a single center retrospective cohort study. Using the outpatient information system of PUMCH, the demographic information and injection-related reaction data of patients undergoing SCIT injection in Allergy Department of PUMCH from December 2018 to December 2022 were retrospectively analyzed to count the incidence and risk factors of systemic allergic reactions caused by SCIT. Mann-Whitney nonparametric test or chi-square test was used for single-factor analysis, and multiple logistic regression was used for multiple-factor analysis. Results: A total of 2 897 patients received 18 070 SCIT injections in Allergy Department during the four years, and 40 systemic allergic reactions occurred, with the overall incidence rate of 0.22%. The incidence of systemic allergic reaction was 0.37% when using imported dust mite preparation and 0.15% when using domestic multi-component allergen preparation. The risk factors significantly related with SCIT-induced systemic allergic reactions in patients using imported dust mite preparation were age less than 18 years old (OR=3.186,95%CI: 1.255-8.085), highest injection concentration (OR value could not be calculated because all patients with systemic reactions were injected with highest concentration), and large local reaction in previous injection (OR=22.264,95%CI: 8.205-60.411). The risk factors for SCIT-induced systemic allergic reactions in patients using domestic allergen preparation were 5 or more types of allergens (OR=3.455,95%CI: 1.147-10.402), highest injection concentration (OR=3.794,95%CI: 1.226-11.740) and large local reaction in previous injection (OR=63.577,95%CI: 22.248-181.683). However, SCIT injection in pollen allergic patients during the pollen season did not show a correlation with systemic allergic reaction. Conclusion: The incidence of SCIT-induced systemic allergic reactions was low in the Chinese patient population of this study. Patients with one or more risk factors, such as multiple allergen injection, highest injection concentration, large local reaction in previous injection, should be given high attention and vigilance against systemic allergic reactions.

[Efficacy and safety of intermediate-dose cytarabine in the treatment of children with refractory high risk Langerhans cell histiocytosis]

Objective: To analyze the efficacy, safety, and long-term prognosis of intermediate-dose cytarabine (Ara-c) regimen in the treatment of children with refractory risk organ involvement Langerhans cell histiocytosis (LCH). Methods: Clinical data of 17 children with multisystem and risk organ involvement LCH who failed the first-line therapy and were treated with intermediate-dose Ara-c (250 mg/m2, twice daily) regimen in the Hematology Center, Beijing Children's Hospital from January 2013 to December 2016 were analyzed retrospectively. In addition to the basic treatment of vindesine and dexamethasone, the patients received two regimens: regimen A: the intermediate-dose Ara-c combined with cladribine and regimen B: the intermediate-dose Ara-c alone. The efficacy, safety and prognosis of the two regimens were analyzed. Results: Among all 17 patients, there were 11 males and 6 females, with the diagnosis age of 2.1 (1.6, 2.7) years. Ten children received regimen A, all of them achieved active disease-better (AD-B) after 8 courses of induction therapy. The disease activity scores (DAS) decreased from 5.5 (3.0, 9.0) to 1.0 (0, 2.3). Seven children received regimen B, and 6 of them achieved AD-B after 8 courses of induction therapy. The DAS decreased from 4.0 (2.0, 4.0) to 1.0 (0, 2.0). The follow-up time was 6.2 (4.9,7.2) and 5.2 (3.7,5.8) years in group A and B. The 5-year overall survival rate was 100.0% in both groups, and the 5-year event free survival rate was (88.9±10.5)% and (85.7±13.2)% in group A and B. Grade 3 or 4 myelosuppression was observed in 8 patients in group A and 2 patients in group B. Conclusions: The intermediate-dose Ara-c regimen (with or without cladribine) is effective and safe for patients with refractory high-risk LCH, with a good long-term prognosis.

Effectiveness of unsupervised primaquine regimen for preventing Plasmodium vivax malaria relapses in northeast Myanmar, a single-arm non-randomized observational study

BACKGROUND

Plasmodium vivax presents a significant challenge for malaria elimination in the Greater Mekong Subregion (GMS). We evaluated the effectiveness of primaquine (PQ) for reducing relapses of vivax malaria.

METHODS

Patients with uncomplicated P. vivax malaria from eastern Myanmar received chloroquine (CQ, 25 mg base/kg given in 3 days) plus unsupervised PQ (0.25 mg/kg/day for 14 days) without screening for glucose-6-phosphate dehydrogenase deficiency and were followed for a year.

RESULTS

Totally 556 patients were enrolled to receive the CQ/PQ treatment from February 2012 to August 2013. During the follow-up, 38 recurrences were detected, presenting a cumulative rate of recurrence of 9.1% (95% confidence interval, 4.1-14.1%). Genotyping at the pvmsp1 and pvmsp3α loci by Amplicon deep sequencing and model prediction indicated that 13 of the 27 recurrences with genotyping data were likely due to relapses. Notably, all confirmed relapses occurred within the first six months.

CONCLUSIONS

The unsupervised standard dose of PQ was highly effective as a radical cure for P. vivax malaria in eastern Myanmar. The high presumed effectiveness might have benefited from the health messages delivered during the enrollment and follow-up activities. Six-month follow-ups in the GMS are sufficient for detecting most relapses.

Distribution of Plasmodium falciparum K13 gene polymorphisms across transmission settings in Ghana

Malaria is a significant global health concern, with a majority of cases in Sub-Saharan African nations. Numerous antimalarial drugs have been developed to counter the rampant prevalence of Plasmodium falciparum malaria. Artemisinin-based Combination Therapy (ACT) has served as the primary treatment of uncomplicated malaria in Ghana since 2005. However, a growing concern has emerged due to the escalating reports of ACT resistance, particularly in Southeast Asia, and its encroachment into Africa. Specifically, mutations in the Kelch propeller domain on chromosome 13 (Pfk13) have been linked to ACT resistance. Yet, our understanding of mutation prevalence in Africa remains largely uncharted. In this study, we compared Pfk13 sequences obtained from 172 P. falciparum samples across three ecological and transmission zones in Ghana. We identified 27 non-synonymous mutations among these sequences, of which two of the mutations, C580Y (found in two samples from the central region) and Y493H (found in one sample from the north), had previously been validated for their association with artemisinin resistance, a phenomenon widespread in Southeast Asia. The Pfk13 gene diversity was most pronounced in the northern savannah than the central forest and south coastal regions, where transmission rates are lower. The observed mutations were not significantly associated with geographical regions, suggesting a frequent spread of mutations across the country. The ongoing global surveillance of artemisinin resistance remains pivotal, and our findings provides insights into the potential spread of resistant parasites in West Africa. Furthermore, the identification of novel codon mutations in this study raises their potential association to ACT resistance, warranting further investigation through in vitro assays to ascertain their functional significance.

Assessment of malaria risk in Southeast Asia: a systematic review

BACKGROUND

Several countries in Southeast Asia are nearing malaria elimination, yet eradication remains elusive. This is largely due to the challenge of focusing elimination efforts, an area where risk prediction can play an essential supporting role. Despite its importance, there is no standard numerical method to quantify the risk of malaria infection. Thus, there is a need for a consolidated view of existing definitions of risk and factors considered in assessing risk to analyse the merits of risk prediction models. This systematic review examines studies of the risk of malaria in Southeast Asia with regard to their suitability in addressing the challenges of malaria elimination in low transmission areas.

METHODS

A search of four electronic databases over 2010-2020 retrieved 1297 articles, of which 25 met the inclusion and exclusion criteria. In each study, examined factors included the definition of the risk and indicators of malaria transmission used, the environmental and climatic factors associated with the risk, the statistical models used, the spatial and temporal granularity, and how the relationship between environment, climate, and risk is quantified.

RESULTS

This review found variation in the definition of risk used, as well as the environmental and climatic factors in the reviewed articles. GLM was widely adopted as the analysis technique relating environmental and climatic factors to malaria risk. Most of the studies were carried out in either a cross-sectional design or case-control studies, and most utilized the odds ratio to report the relationship between exposure to risk and malaria prevalence.

CONCLUSIONS

Adopting a standardized definition of malaria risk would help in comparing and sharing results, as would a clear description of the definition and method of collection of the environmental and climatic variables used. Further issues that need to be more fully addressed include detection of asymptomatic cases and considerations of human mobility. Many of the findings of this study are applicable to other low-transmission settings and could serve as a guideline for further studies of malaria in other regions.

A nanoparticle vaccine displaying the ookinete PSOP25 antigen elicits transmission-blocking antibody response against Plasmodium berghei

BACKGROUND

Safe and effective vaccines are crucial for the control and eventual elimination of malaria. Novel approaches to optimize and improve vaccine efficacy are urgently required. Nanoparticle-based delivery platforms are considered potent and powerful tools for vaccine development.

METHODS

In this study, we developed a transmission-blocking vaccine against malaria by conjugating the ookinete surface antigen PSOP25 to the Acinetobacter phage coat protein AP205, forming virus-like particles (VLPs) using the SpyTag/SpyCatcher adaptor system. The combination of AP205-2*SpyTag with PSOP25-SpyCatcher resulted in the formation of AP205-PSOP25 complexes (VLP-PSOP25). The antibody titers and avidity of serum from each immunization group were assessed by ELISA. Western blot and IFA were performed to confirm the specific reactivity of the elicit antisera to the native PSOP25 in Plasmodium berghei ookinetes. Both in vitro and in vivo assays were conducted to evaluate the transmission-blocking activity of VLP-PSOP25 vaccine.

RESULTS

Immunization of mice with VLP-PSOP25 could induced higher levels of high-affinity antibodies than the recombinant PSOP25 (rPSOP25) alone or mixtures of untagged AP205 and rPSOP25 but was comparable to rPSOP25 formulated with alum. Additionally, the VLP-PSOP25 vaccine enhanced Th1-type immune response with remarkably increased levels of IgG2a subclass. The antiserum generated by VLP-PSOP25 specifically recognizes the native PSOP25 antigen in P. berghei ookinetes. Importantly, antisera generated by inoculation with the VLP-PSOP25 could inhibit ookinete development in vitro and reduce the prevalence of infected mosquitoes or oocyst intensity in direct mosquito feeding assays.

CONCLUSIONS

Antisera elicited by immunization with the VLP-PSOP25 vaccine confer moderate transmission-reducing activity and transmission-blocking activity. Our results support the utilization of the AP205-SpyTag/SpyCatcher platform for next-generation TBVs development.

Enterococcus faecium supplementation prevents enteritis caused by Escherichia coli in goats

The probiotic Enterococcus faecium is a gut microbe with immunomodulatory effects, which has been widely used to prevent diarrhoea in pigs and birds. Escherichia coli is a common pathogen that causes inflammatory bowel disease in animals. The aim of this study was to investigate the protective effects of E. faecium on enteritis in goats. Forty goats were randomly divided into 4 treatment groups: control, E. faecium, E. coli, and E. faecium + E. coli. The changes of physiological indicators and diarrhoea scoring were evaluated on days -4, -2, 0, 2, 4, 6, and 8. The pathological examination, inflammatory cytokines mRNA expression and bacterial counts in jejunum and caecum were detected on day 4 and 8. The results showed that body temperature, respiratory rate, heart rate and leukocyte counts all increased from the 2nd to the 6th day after feeding with E. coli, and the diarrhoea score was significantly increased. However, E. faecium-pretreated goats had lower body temperatures and fewer leukocytes than E. coli-treated goats on day 2, as well as decreased diarrhoea scores. E. coli treatment caused histopathological damage and morphological changes in the jejunum and caecum, while pretreatment with E. faecium significantly alleviated these injuries. E. faecium pretreatment can reduce the load of E. coli and increase the prevalence of Lactobacillus, thereby balancing the microbiota in the intestine. Furthermore, E. coli-infected goats pretreated with E. faecium showed obvious inhibition of Toll-like receptor 4, interleukin (IL)-1β, IL-6, IL-8 and tumour necrosis factor-α mRNA expression in the jejunum and caecum compared to that in the E. coli treatment group. In conclusion, the addition of E. faecium to goat feed is beneficial for improving clinical symptoms, maintaining intestinal mucosa integrity, balancing the microbiota and decreasing inflammatory responses in E. coli-induced intestinal injury.

MalariaSED: a deep learning framework to decipher the regulatory contributions of noncoding variants in malaria parasites

Malaria remains one of the deadliest infectious diseases. Transcriptional regulation effects of noncoding variants in this unusual genome of malaria parasites remain elusive. We developed a sequence-based, ab initio deep learning framework, MalariaSED, for predicting chromatin profiles in malaria parasites. The MalariaSED performance was validated by published ChIP-qPCR and TF motifs results. Applying MalariaSED to ~ 1.3 million variants shows that geographically differentiated noncoding variants are associated with parasite invasion and drug resistance. Further analysis reveals chromatin accessibility changes at Plasmodium falciparum rings are partly associated with artemisinin resistance. MalariaSED illuminates the potential functional roles of noncoding variants in malaria parasites.

Effect of adherence to primaquine on the risk of Plasmodium vivax recurrence: a WorldWide Antimalarial Resistance Network systematic review and individual patient data meta-analysis

BACKGROUND

Imperfect adherence is a major barrier to effective primaquine radical cure of Plasmodium vivax. This study investigated the effect of reduced adherence on the risk of P. vivax recurrence.

METHODS

Efficacy studies of patients with uncomplicated P. vivax malaria, including a treatment arm with daily primaquine, published between January 1999 and March 2020 were identified. Individual patient data from eligible studies were pooled using standardized methodology. Adherence to primaquine was inferred from i) the percentage of supervised doses and ii) the total mg/kg dose received compared to the target total mg/kg dose per protocol. The effect of adherence to primaquine on the incidence of P. vivax recurrence between days 7 and 90 was investigated by Cox regression analysis.

RESULTS

Of 82 eligible studies, 32 were available including 6917 patients from 18 countries. For adherence assessed by percentage of supervised primaquine, 2790 patients (40.3%) had poor adherence (≤ 50%) and 4127 (59.7%) had complete adherence. The risk of recurrence by day 90 was 14.0% [95% confidence interval: 12.1-16.1] in patients with poor adherence compared to 5.8% [5.0-6.7] following full adherence; p = 0.014. After controlling for age, sex, baseline parasitaemia, and total primaquine dose per protocol, the rate of the first recurrence was higher following poor adherence compared to patients with full adherence (adjusted hazard ratio (AHR) = 2.3 [1.8-2.9]). When adherence was quantified by total mg/kg dose received among 3706 patients, 347 (9.4%) had poor adherence, 88 (2.4%) had moderate adherence, and 3271 (88.2%) had complete adherence to treatment. The risks of recurrence by day 90 were 8.2% [4.3-15.2] in patients with poor adherence and 4.9% [4.1-5.8] in patients with full adherence; p < 0.001.

CONCLUSION

Reduced adherence, including less supervision, increases the risk of vivax recurrence.

Interventions for promoting patients' adherence to 14-day primaquine treatment in a highly malaria-endemic township in Myanmar: a qualitative study among key stakeholders

BACKGROUND

Plasmodium vivax malaria is considered a major threat to malaria eradication. The radical cure for P. vivax malaria normally requires a 14-day administration of primaquine (PQ) to clear hypnozoites. However, maintaining adherence to PQ treatment is a significant challenge, particularly in malaria-endemic rural areas. Hence, this study aimed to formulate interventions for promoting patients' commitment to PQ treatment in a highly malaria-endemic township in Myanmar.

METHODS

A qualitative study was conducted in Waingmaw Township in northern Myanmar, where P. vivax malaria is highly endemic. Key stakeholders including public health officers and community members participated in focus group discussions (FGDs) and in-depth interviews (IDIs) in September 2022. Data were collected using validated guidelines, translated into English, and visualized through thematic analysis.

RESULTS

Responsible individuals from different levels of the Myanmar National Malaria Control Programme participated in the IDIs. Most of them reported being aware of the markedly increasing trend of P. vivax and the possibility of relapse cases, especially among migrants who are lost to follow-up. Workload was a key concern surrounding intervention implementation. The respondents discussed possible interventions, such as implementing directly observed treatment (DOT) by family members, piloting a shorter PQ regimen, expanding the community's malaria volunteer network, and strengthening health education activities using local languages to promote reasonable drug adherence. FGDs among community members revealed that although people were knowledgeable about malaria symptoms, places to seek treatment, and the use of bed nets to prevent mosquito bites, most of them still preferred to be treated by quack doctors and rarely used insecticide-treated nets at worksites. Many often stopped taking the prescribed drugs once the symptoms disappeared. Nevertheless, some respondents requested more bed nets to be distributed and health promotion activities to be conducted.

CONCLUSION

In rural areas where human resources are limited, interventions such as implementing family member DOT or shortening PQ regimens should be introduced to enhance the radical cure for the P. vivax infection. Disseminating information about the importance of taking the entire treatment course and emphasizing the burden of relapse is also essential.

[The value of a nomogram for predicting the outcome of intracerebral hemorrhage based on clinical characteristics and diffusion-weighted imaging of hyperintense lesions]

Objective: To investigate the value of a nomogram predicting the outcome of intracerebral hemorrhage (ICH) based on clinical characteristics and diffusion-weighted imaging (DWI) of hyperintense lesions. Methods: A case-control study. Consecutive patients, aged 30-88(59±13) years old, with ICH were recruited at the Stroke Center of Zhengzhou People's Hospital from January 2018 to August 2021. Patients were divided into a group with DWI lesions and a group without DWI lesions depending on whether there were DWI hyperintense lesions distant from the hematoma. Prognosis was evaluated at 90 days via the modified Rankin Scale (mRS). Univariate and multivariable logistic regression models were used to identify independent predictors of a poor ICH outcome (mRS score≥4), and a nomogram model was developed. The performance of the nomogram was validated via the area under the receiver operating characteristic curve (AUC) and a calibration chart. Results: Of the 303 patients included in the study, 24.8% presented with DWI lesions; 17.5% with asymptomatic DWI lesions and 7.3% with symptomatic DWI lesions. Poor outcomes were significantly more frequent in the group with DWI lesions than in the group without DWI lesions (χ2=21.32, P<0.001). In multivariable regression analysis, age [odds ratio (OR)=1.032, 95% confidence interval (CI) 1.002-1.063, P=0.035], hematoma volume (OR=1.050, 95%CI 1.011-1.090, P=0.012), hematoma location (OR=3.839, 95%CI 1.248-11.805, P=0.019), DWI lesions (OR=3.955, 95%CI 1.906-8.206, P<0.001), and baseline NIHSS scores (OR=1.102, 95%CI 1.038-1.170, P=0.001) were independent predictors of a poor outcome. In subgroup analysis patients with asymptomatic DWI lesions had a 3-fold greater risk of a poor outcome compared to those without DWI lesions (OR=3.135, 95%CI 1.382-7.112, P=0.006), and patients with symptomatic DWI lesions had a 7-fold greater risk of a poor outcome compared to those without DWI lesions (OR=7.126, 95%CI 2.279-22.277, P=0.001). A nomogram model was established based on the independent predictors for a poor outcome. The AUC of the nomogram was 0.846 (95%CI 0.795-0.898), and a calibration chart indicated good consistency between values predicted by the nomogram and actual observed values. Conclusions: DWI lesions are an independent risk factor for a poor outcome in patients with ICH-particularly symptomatic DWI lesions. A nomogram model based on clinical characteristics and DWI lesions exhibited good efficacy when predicting the outcome of ICH.

Interventions for promoting patients' adherence to 14-day primaquine treatment in a highly malaria-endemic township in Myanmar: A qualitative study among key stakeholders

Background

Plasmodium vivax malaria is considered a major threat to malaria eradication. The radical cure for P. vivax malaria normally requires a 14-day administration of primaquine (PQ) to clear hypnozoites. However, maintaining adherence to PQ treatment is a significant challenge, particularly in malaria-endemic rural areas. Hence, this study aimed to formulate interventions for promoting patients' commitment to PQ treatment in a highly malaria-endemic township in Myanmar.

Methods

A qualitative study was conducted in Waingmaw Township in northern Myanmar, where P. vivax malaria is highly endemic. Key stakeholders including public health officers and community members participated in focus group discussions (FGDs) and in-depth interviews (IDIs) in September 2022. Data were collected using validated guidelines, translated into English, and visualized through thematic analysis.

Results

Responsible individuals from different levels of the Myanmar National Malaria Control Program participated in the IDIs. Most of them reported being aware of the markedly increasing trend of P. vivax and the possibility of relapse cases, especially among migrants who are lost to follow-up. Workload was a key concern surrounding intervention implementation. The respondents discussed possible interventions, such as implementing directly observed treatment (DOT) by family members, piloting a shorter PQ regimen, expanding the community's malaria volunteer network, and strengthening health education activities using local languages to promote reasonable drug adherence. FGDs among community members revealed that although people were knowledgeable about malaria symptoms, places to seek treatment, and the use of bed nets to prevent mosquito bites, most of them still preferred to be treated by quack doctors and rarely used insecticide-treated nets at worksites. Many often stopped taking the prescribed drugs once the symptoms disappeared. Nevertheless, some respondents requested more bed nets to be distributed and health promotion activities to be conducted.

Conclusion

In rural areas where human resources are limited, interventions such as implementing family member DOT or shortening PQ regimens should be introduced to enhance the radical cure for the P. vivax infection. Disseminating information about the importance of taking the entire treatment course and emphasizing the burden of relapse is also essential.

Genetic diversity and molecular evolution of Plasmodium vivax Duffy Binding Protein and Merozoite Surface Protein-1 in northwestern Thailand

The local diversity and population structure of malaria parasites vary across different regions of the world, reflecting variations in transmission intensity, host immunity, and vector species. This study aimed to use amplicon sequencing to investigate the genotypic patterns and population structure of P. vivax isolates from a highly endemic province of Thailand in recent years. Amplicon deep sequencing was performed on 70 samples for the 42-kDa region of pvmsp1 and domain II of pvdbp. Unique haplotypes were identified and a network constructed to illustrate genetic relatedness in northwestern Thailand. Based on this dataset of 70 samples collected between 2015 and 2021, 16 and 40 unique haplotypes were identified in pvdbpII and pvmsp142kDa, respectively. Nucleotide diversity was higher in pvmsp142kDa than in pvdbpII (π = 0.027 and 0.012), as was haplotype diversity (Hd = 0.962 and 0.849). pvmsp142kDa also showed a higher recombination rate and higher levels of genetic differentiation (Fst) in northwestern Thailand versus other regions (0.2761-0.4881). These data together suggested that the genetic diversity of P. vivax in northwestern Thailand at these two studied loci evolved under a balancing selection, most likely host immunity. The lower genetic diversity of pvdbpII may reflect its stronger functional constrain. In addition, despite the balancing selection, a decrease in genetic diversity was observed. Hd of pvdbpII decreased from 0.874 in 2015-2016 to 0.778 in 2018-2021; π of pvmsp142kDa decreased from 0.030 to 0.022 over the same period. Thus, the control activities must have had a strong impact on the parasite population size. The findings from this study provide an understanding of P. vivax population structure and the evolutionary force on vaccine candidates. They also established a new baseline for tracking future changes in P. vivax diversity in the most malarious area of Thailand.

Antennal morphology and sensilla ultrastructure of the malaria vectors, Anopheles maculatus and An. sawadwongporni (Diptera: Culicidae)

Mosquitoes rely mainly on the olfactory system to track hosts. Sensilla contain olfactory neuron receptors that perceive different kinds of odorants and transfer crucial information regarding the surrounding environment. Anopheles maculatus and An. sawadwongporni, members of the Maculatus Group, are regarded as vectors of malaria in Thailand. The fine structure of their sensilla has yet to be identified. Herein, scanning electron microscopy is used to examine the sensilla located on the antennae of adults An. maculatus and An. sawadwongporni, collected from the Thai-Myanmar border. Four major types of antennal sensilla are discovered in both species: chaetica, coeloconica, basiconica (grooved pegs) and trichodea. The antennae of female An. maculatus have longer lengths (μm, mean ± SE) in the long sharp-tipped trichodea (40.62 ± 0.35 > 38.20 ± 0.36), blunt-tipped trichodea (20.39 ± 0.62 > 18.62 ± 0.35), and basiconica (7.84 ± 0.15 > 7.41 ± 0.12) than those of An. sawadwongporni. Using light microscopy, it is found that the mean numbers of large sensilla coeloconica (lco) on both flagella in An. maculatus (left: 32.97 ± 0.48; right: 33.27 ± 0.65) are also greater when compared to An. sawadwongporni (left: 30.40 ± 0.62; right: 29.97 ± 0.49). The mean counts of lco located on flagellomeres 1-3, 6, and 9 in An. maculatus are significantly higher than those of An. sawadwongporni. The data in this study indicate that two closely related Anopheles species exhibit similar morphology of sensilla types, but show variations in length, and likewise in the number of large sensilla coeloconica between them, suggesting they might be causative factors that affect their behaviors driven by the sense of smell.

Preliminary characterization of Plasmodium vivax sporozoite antigens as pre-erythrocytic vaccine candidates

Plasmodium vivax pre-erythrocytic (PE) vaccine research has lagged far behind efforts to develop Plasmodium falciparum vaccines. There is a critical gap in our knowledge of PE antigen targets that can induce functionally inhibitory neutralizing antibody responses. To overcome this gap and guide the selection of potential PE vaccine candidates, we considered key characteristics such as surface exposure, essentiality to infectivity and liver stage development, expression as recombinant proteins, and functional immunogenicity. Selected P. vivax sporozoite antigens were surface sporozoite protein 3 (SSP3), sporozoite microneme protein essential for cell traversal (SPECT1), sporozoite surface protein essential for liver-stage development (SPELD), and M2 domain of MAEBL. Sequence analysis revealed little variation occurred in putative B-cell and T-cell epitopes of the PE candidates. Each antigen was tested for expression as refolded recombinant proteins using an established bacterial expression platform and only SPELD failed. The successfully expressed antigens were immunogenic in vaccinated laboratory mice and were positively reactive with serum antibodies of P. vivax-exposed residents living in an endemic region in Thailand. Vaccine immune antisera were tested for reactivity to native sporozoite proteins and for their potential vaccine efficacy using an in vitro inhibition of liver stage development assay in primary human hepatocytes quantified on day 6 post-infection by high content imaging analysis. The anti-PE sera produced significant inhibition of P. vivax sporozoite invasion and liver stage development. This report provides an initial characterization of potential new PE candidates for a future P. vivax vaccine.

A novel Modulator of Ring Stage Translation (MRST) gene alters artemisinin sensitivity in Plasmodium falciparum

The implementation of artemisinin (ART) combination therapies (ACTs) has greatly decreased deaths caused by Plasmodium falciparum malaria, but increasing ACT resistance in Southeast Asia and Africa could reverse this progress. Parasite population genetic studies have identified numerous genes, single-nucleotide polymorphisms (SNPs), and transcriptional signatures associated with altered artemisinin activity with SNPs in the Kelch13 (K13) gene being the most well-characterized artemisinin resistance marker. However, there is an increasing evidence that resistance to artemisinin in P. falciparum is not related only to K13 SNPs, prompting the need to characterize other novel genes that can alter ART responses in P. falciparum. In our previous analyses of P. falciparum piggyBac mutants, several genes of unknown function exhibited increased sensitivity to artemisinin that was similar to a mutant of K13. Further analysis of these genes and their gene co-expression networks indicated that the ART sensitivity cluster was functionally linked to DNA replication and repair, stress responses, and maintenance of homeostatic nuclear activity. In this study, we have characterized PF3D7_1136600, another member of the ART sensitivity cluster. Previously annotated as a conserved Plasmodium gene of unknown function, we now provide putative annotation of this gene as a Modulator of Ring Stage Translation (MRST). Our findings reveal that the mutagenesis of MRST affects gene expression of multiple translation-associated pathways during the early ring stage of asexual development via putative ribosome assembly and maturation activity, suggesting an essential role of MRST in protein biosynthesis and another novel mechanism of altering the parasite's ART drug response.IMPORTANCEPlasmodium falciparum malaria killed more than 600,000 people in 2021, though ACTs have been critical in reducing malaria mortality as a first-line treatment for infection. However, ACT resistance in Southeast Asia and emerging resistance in Africa are detrimental to this progress. Mutations to Kelch13 (K13) have been identified to confer increased artemisinin tolerance in field isolates, however, genes other than K13 are implicated in altering how the parasite responds to artemisinin prompts additional analysis. Therefore, in this study we have characterized a P. falciparum mutant clone with altered sensitivity to artemisinin and identified a novel gene (PF3D7_1136600) that is associated with alterations to parasite translational metabolism during critical timepoints for artemisinin drug response. Many genes of the P. falciparum genome remain unannotated, posing a challenge for drug-gene characterizations in the parasite. Therefore, through this study, we have putatively annotated PF3D7_1136600 as a novel MRST gene and have identified a potential link between MRST and parasite stress response mechanisms.

Spatiotemporal characteristics of ozone and the formation sensitivity over the Fenwei Plain

High surface ozone (O₃) levels affect human and environmental health. The Fenwei Plain (FWP), one of the critical regions for China's "Blue Sky Protection Campaign", has reported severe O₃ pollution. This study investigates the spatiotemporal properties and the causes of O₃ pollution over the FWP using high-resolution data from the TROPOspheric Monitoring Instrument (TROPOMI) from 2019 to 2021. This study characterizes spatial and temporal variations in O₃ concentration by linking O₃ columns and surface monitoring using a trained deep forest machine learning model. O₃ concentrations in summer were 2-3 times higher than those found in winter due to higher temperatures and greater solar irradiation. The spatial distributions of O₃ correlate with the solar radiation showing decreased trends from the northeastern to the southwestern FWP, with the highest O₃ values in Shanxi Province and the lowest in Shaanxi Province. For urban areas, croplands and grasslands, the O₃ photochemistry in summer is NO_x-limited or in the transitional regime, while it is VOC-limited in winter and other seasons. Reducing NO_x emissions would be effective for decreasing O₃ levels in summer, while VOC reductions are necessary for winter. The annual cycle in vegetated areas included both NO_x-limited and transitional regimes, indicating the importance of NO_x controls to protect ecosystems. The O₃ response to limiting precursors shown here is of importance for optimizing control strategies and is illustrated by emission changes during the 2020 COVID-19 outbreak.

A type II protein arginine methyltransferase regulates merozoite invasion in Plasmodium falciparum

Protein arginine methyltransferases (PRMTs) regulate many important cellular processes, such as transcription and RNA processing in model organisms but their functions in human malaria parasites are not elucidated. Here, we characterize PfPRMT5 in Plasmodium falciparum, which catalyzes symmetric dimethylation of histone H3 at R2 (H3R2me2s) and R8, and histone H4 at R3 in vitro. PfPRMT5 disruption results in asexual stage growth defects primarily due to lower invasion efficiency of the merozoites. Transcriptomic analysis reveals down-regulation of many transcripts related to invasion upon PfPRMT5 disruption, in agreement with H3R2me2s being an active chromatin mark. Genome-wide chromatin profiling detects extensive H3R2me2s marking of genes of different cellular processes, including invasion-related genes in wildtype parasites and PfPRMT5 disruption leads to the depletion of H3R2me2s. Interactome studies identify the association of PfPRMT5 with invasion-related transcriptional regulators such as AP2-I, BDP1, and GCN5. Furthermore, PfPRMT5 is associated with the RNA splicing machinery, and PfPRMT5 disruption caused substantial anomalies in RNA splicing events, including those for invasion-related genes. In summary, PfPRMT5 is critical for regulating parasite invasion and RNA splicing in this early-branching eukaryote.

Plasmodium falciparum GAP40 Plays an Essential Role in Merozoite Invasion and Gametocytogenesis

Cyclic invasion of red blood cells (RBCs) by Plasmodium merozoites is associated with the symptoms and pathology of malaria. Merozoite invasion is powered actively and rapidly by a parasite actomyosin motor called the glideosome. The ability of the glideosome to generate force to support merozoite entry into the host RBCs is thought to rely on its stable anchoring within the inner membrane complex (IMC) through membrane-resident proteins, such as GAP50 and GAP40. Using a conditional knockdown (KD) approach, we determined that PfGAP40 was required for asexual blood-stage replication. PfGAP40 is not needed for merozoite egress from host RBCs or for the attachment of merozoites to new RBCs. PfGAP40 coprecipitates with PfGAP45 and PfGAP50. During merozoite invasion, PfGAP40 is associated strongly with stabilizing the expression levels of PfGAP45 and PfGAP50 in the schizont stage. Although PfGAP40 KD did not influence IMC integrity, it impaired the maturation of gametocytes. In addition, PfGAP40 is phosphorylated, and mutations that block phosphorylation of PfGAP40 at the C-terminal serine residues S370, S372, S376, S405, S409, S420, and S445 reduced merozoite invasion efficiency. Overall, our findings implicate PfGAP40 as an important regulator for the gliding activity of merozoites and suggest that phosphorylation is required for PfGAP40 function. IMPORTANCE Red blood cell invasion is central to the pathogenesis of the malaria parasite, and the parasite proteins involved in this process are potential therapeutic targets. Gliding motility powers merozoite invasion and is driven by a unique molecular motor termed the glideosome. The glideosome is stably anchored to the parasite inner membrane complex (IMC) through membrane-resident proteins. In the present study, we demonstrate the importance of an IMC-resident glideosome component, PfGAP40, that plays a critical role in stabilizing the expression levels of glideosome components in the schizont stage. We determined that phosphorylation of PfGAP40 at C-terminal residues is required for efficient merozoite invasion.

Projecting malaria elimination in Thailand using Bayesian hierarchical spatiotemporal models

Thailand has set a goal of eliminating malaria by 2024 in its national strategic plan. In this study, we used the Thailand malaria surveillance database to develop hierarchical spatiotemporal models to analyze retrospective patterns and predict Plasmodium falciparum and Plasmodium vivax malaria incidences at the provincial level. We first describe the available data, explain the hierarchical spatiotemporal framework underlying the analysis, and then display the results of fitting various space-time formulations to the malaria data with the different model selection metrics. The Bayesian model selection process assessed the sensitivity of different specifications to obtain the optimal models. To assess whether malaria could be eliminated by 2024 per Thailand's National Malaria Elimination Strategy, 2017-2026, we used the best-fitted model to project the estimated cases for 2022-2028. The study results based on the models revealed different predicted estimates between both species. The model for P. falciparum suggested that zero P. falciparum cases might be possible by 2024, in contrast to the model for P. vivax, wherein zero P. vivax cases might not be reached. Innovative approaches in the P. vivax-specific control and elimination plans must be implemented to reach zero P. vivax and consequently declare Thailand as a malaria-free country.

Dual-pharmacophore artezomibs hijack the Plasmodium ubiquitin-proteasome system to kill malaria parasites while overcoming drug resistance

Artemisinins (ART) are critical anti-malarials and despite their use in combination therapy, ART-resistant Plasmodium falciparum is spreading globally. To counter ART resistance, we designed artezomibs (ATZs), molecules that link an ART with a proteasome inhibitor (PI) via a non-labile amide bond and hijack parasite's own ubiquitin-proteasome system to create novel anti-malarials in situ. Upon activation of the ART moiety, ATZs covalently attach to and damage multiple parasite proteins, marking them for proteasomal degradation. When damaged proteins enter the proteasome, their attached PIs inhibit protease function, potentiating the parasiticidal action of ART and overcoming ART resistance. Binding of the PI moiety to the proteasome active site is enhanced by distal interactions of the extended attached peptides, providing a mechanism to overcome PI resistance. ATZs have an extra mode of action beyond that of each component, thereby overcoming resistance to both components, while avoiding transient monotherapy seen when individual agents have disparate pharmacokinetic profiles.

Prevalence of G6PD deficiency and diagnostic accuracy of a G6PD point-of-care test among a population at risk of malaria in Myanmar

BACKGROUND

Over the past decade, the incidence of malaria has steadily declined in Myanmar, with Plasmodium vivax becoming predominant. The resilience of P. vivax to malaria control is attributed to the parasite's ability to form hypnozoites in the host's liver, which can cause relapse. Primaquine is used to eliminate hypnozoites but can cause haemolysis in glucose-6-phosphate dehydrogenase (G6PD)-deficient individuals. It is thus necessary to estimate the frequency and variant types of G6PD deficiency in areas where primaquine will be widely used for P. vivax elimination.

METHODS

In this study, a descriptive cross-sectional survey was conducted to determine the prevalence of G6PD deficiency in a population residing in Nay Pyi Taw, Myanmar, using a standard spectrophotometric assay, a rapid diagnostic test (RDT), Biosensor, and by genotyping G6PD variants.

RESULTS

G6PD enzyme activity was determined from 772 leukocyte-depleted samples, with an adjusted male median G6PD activity value of 6.3 U/g haemoglobin. Using a cut-off value of 30% enzyme activity, the overall prevalence of G6PD deficiency was 10.8%. Genotyping of G6PD variants was performed for 536 samples, of which 131 contained mutations. The Mahidol variant comprised the majority, and males with the Mahidol variant showed lower G6PD enzyme activity. The G6PD Andalus variant, which has not been reported in Myanmar before, was also identified in this study.

CONCLUSION

This study provides a G6PD enzyme activity reference value for the Myanmar population and further information on the prevalence and variants of G6PD deficiency among the Myanmar population; it also evaluates the feasibility of G6PD deficiency tests.

Characterizing the Wolbachia infection in field-collected Culicidae mosquitoes from Hainan Province, China

BACKGROUND

Mosquitoes are vectors of many pathogens, such as malaria, dengue virus, yellow fever virus, filaria and Japanese encephalitis virus. Wolbachia are capable of inducing a wide range of reproductive abnormalities in their hosts, such as cytoplasmic incompatibility. Wolbachia has been proposed as a tool to modify mosquitoes that are resistant to pathogen infection as an alternative vector control strategy. This study aimed to determine natural Wolbachia infections in different mosquito species across Hainan Province, China.

METHODS

Adult mosquitoes were collected using light traps, human landing catches and aspirators in five areas in Hainan Province from May 2020 to November 2021. Species were identified based on morphological characteristics, species-specific PCR and DNA barcoding of cox1 assays. Molecular classification of species and phylogenetic analyses of Wolbachia infections were conducted based on the sequences from PCR products of cox1, wsp, 16S rRNA and FtsZ gene segments.

RESULTS

A total of 413 female adult mosquitoes representing 15 species were identified molecularly and analyzed. Four mosquito species (Aedes albopictus, Culex quinquefasciatus, Armigeres subalbatus and Culex gelidus) were positive for Wolbachia infection. The overall Wolbachia infection rate for all mosquitoes tested in this study was 36.1% but varied among species. Wolbachia types A, B and mixed infections of A × B were detected in Ae. albopictus mosquitoes. A total of five wsp haplotypes, six FtsZ haplotypes and six 16S rRNA haplotypes were detected from Wolbachia infections. Phylogenetic tree analysis of wsp sequences classified them into three groups (type A, B and C) of Wolbachia strains compared to two groups each for FtsZ and 16S rRNA sequences. A novel type C Wolbachia strain was detected in Cx. gelidus by both single locus wsp gene and the combination of three genes.

CONCLUSION

Our study revealed the prevalence and distribution of Wolbachia in mosquitoes from Hainan Province, China. Knowledge of the prevalence and diversity of Wolbachia strains in local mosquito populations will provide part of the baseline information required for current and future Wolbachia-based vector control approaches to be conducted in Hainan Province.

Factors hindering coverage of targeted mass treatment with primaquine in a malarious township of northern Myanmar in 2019-2020

Targeted mass primaquine treatment (TPT) might be an effective intervention to facilitate elimination of vivax malaria in Myanmar by 2030. In this study, we explored the factors hindering coverage of a TPT campaign conducted in a malarious township of northern Myanmar. From August 2019 to July 2020, a cross-sectional exploratory design including quantitative and qualitative data was conducted in five villages with high P. vivax prevalence following a TPT campaign. Among a targeted population of 2322; 1973 (85.0%) participated in the baseline mass blood survey (MBS) and only 52.0% of the total targeted population (1208, 91.9% of total eligible population) completed the TPT. G6PD deficiency was found among 13.5% of total MBS participants and those were excluded from TPT. Of 1315 eligible samples, farmers and gold miners, males, and those aged 15 to 45 years had higher percentages of non-participation in TPT. Qualitative findings showed that most of the non-participation groups were outside the villages during TPT because of time-sensitive agricultural and other occupational or education-related purposes. In addition to mitigating of some inclusion criteria (i.e. including young children or offering weekly PQ treatment to G6PD deficient individuals), strengthening community awareness and increasing engagement should be pursued to increase community participation.

Characterization of the dual role of Plasmodium falciparum DNA methyltransferase in regulating transcription and translation

DNA modifications are critical in fine-tuning the biological processes in model organisms. However, the presence of cytosine methylation (5mC) and the function of the putative DNA methyltransferase, PfDNMT2, in the human malaria pathogen, Plasmodium falciparum, remain controversial. Here, we revisited the 5mC in the parasite genome and the function of PfDNMT2. Low levels of genomic 5mC (0.1-0.2%) during asexual development were identified using a sensitive mass spectrometry procedure. Native PfDNMT2 displayed substantial DNA methylation activities, and disruption or overexpression of PfDNMT2 resulted in reduced or elevated genomic 5mC levels, respectively. PfDNMT2 disruption led to an increased proliferation phenotype, with the parasites having an extended schizont stage and producing a higher number of progenies. Consistent with PfDNMT2's interaction with an AP2 domain-containing transcription factor, transcriptomic analyses revealed that PfDNMT2 disruption led to a drastic alteration in the expression of many genes, some of which provided the molecular basis of enhanced proliferation after PfDNMT2 disruption. Furthermore, levels of tRNAAsp and its methylation rate at position C38, and the translation of a reporter containing an aspartate repeat were significantly reduced after PfDNMT2 disruption, while the levels of tRNAAsp and its C38 methylation were restored after complementation of PfDNMT2. Our study sheds new light on the dual function of PfDNMT2 during P. falciparum asexual development.

Evolution of Plasmodium falciparum antimalarial drug resistance markers post-adoption of artemisinin-based combination therapies in Yaounde, Cameroon

OBJECTIVES

This study aimed to investigate the evolution of Plasmodium falciparum antimalarial drug resistance markers by comparing pre- and post-adoption of artemisinin-based combination therapies (ACTs) in Yaounde, Cameroon.

METHODS

The molecular characterization of known antimalarial drug resistance markers (Pfcrt, Pfmdr1, Pfdhfr, Pfdhps and Pfk13) of P. falciparum positive samples collected in 2014 and 2019-2020 was achieved using nested PCR followed by targeted amplicon deep sequencing on the Illumina MiSeq platform. Data derived were compared with those published during the pre-ACT adoption period from 2004-2006.

RESULTS

High prevalence of Pfmdr1 184F, Pfdhfr 51I/59R/108N, and Pfdhps 437G mutant alleles were observed during the post-ACT adoption. The Pfcrt 76T and Pfmdr1 86Y mutant alleles significantly declined between 2004 and 2020 (P<0.0001). Conversely, resistance markers to antifolates, Pfdhfr 51I/59R/108N and Pfdhps 437G, significantly increased during the same study period (P<0.0001). We identified 9 mutations in the propeller domains of Pfk13, although they were all present in single parasite isolates, and none of them were validated to confer artemisinin resistance.

CONCLUSIONS

This study documented a near complete reversion to sensitive parasites for markers conferring resistance to the 4-aminoquinolines and arylamino alcohols in Yaounde. Contrariwise, the Pfdhfr mutations associated with pyrimethamine resistance are moving towards saturation.

[The predictive value of warning scores for intensive care unit admission in coronavirus disease 2019 patients]

To evaluate the predictive value of early warning scores for intensive care unit (ICU) admission in patients with coronavirus disease 2019 (COVID-19). For COVID-19 patients who were admitted to Shijiazhuang People's Hospital from January 2021 to February 2021, national early warning score (NEWS), national early warning score 2 (NEWS2), rapid emergency medicine score (REMS), quick sepsis-related organ failure (qSOFA), altered consciousness, blood urea nitrogen, respiratory rate, blood pressure, and age-65 (CURB-65) were used to evaluate the inpatient condition and the predictive value for ICU admission. A total of 368 patients were included, and 32 patients (8.7%) were transferred to the ICU. The median age was 49.0 (34.0,61.0) years. The scores of NEWS, NEWS2, REMS, and CURB-65 were 1 (0, 2), 1 (0, 2), 4 (2, 6) and 0 (0, 1), respectively. The receiver operating characteristic (ROC) cure (AUC) was used to evaluate the predictive value in detecting patients who are at risk of being transferred to the ICU. Area under the ROC AUC of NEWS was 0.756, sensitivity 65.6%, and specificity 71.3%. ROC AUC of NEWS2 was 0.732, sensitivity 62.5%, and specificity 61.3%. ROC AUC of REMS was 0.787, sensitivity 84.4%, and specificity 64.6%. ROC AUC of CURB-65 was 0.814, sensitivity 81.3%, and specificity 76.8%. The predictive value of NEWS and NEWS2 combined with age were significantly improved. The ROC AUC of NEWS combined with age was 0.885, sensitivity 85.1%, and specificity 75.0%. The ROC AUC of NEWS2 combined with age was 0.883, sensitivity 84.2%, and specificity 75.0%. NEWS and NEWS2 combined with age can be used as a predictive tool for whether COVID-19 patients will be admitted to the ICU.

[Effect of adjunctive drug therapy on early expulsion of distal ureteral calculi after extracorporeal shock wave lithotripsy]

Objective: To evaluate the efficacy of ketochromate tromethamine and phloroglucinol combination therapy in early expulsion of ureteral calculi after extracorporeal shockwave lithotripsy (ESWL) in patients with distal ureteral clculi. The clinical and follow-up data of 275 patients with lower ureteral calculi who underwent ESWL were collected retrospectively in Civil Aviation General Hospital from January 1^st 2021 to June 30^th 2021. According to whether adjunctive medication used before ESWL patients were divided into control group and medication group (with ketochromate tromethamine 30 mg and phloroglucinol 80 mg before ESWL). Primary endpoint is the clearance rate of ureteral calculi after ESWL, secondary endpoint are the other outcomes and drug allergy. There were 138 cases in control group [117 were males and mean age (42±13) years]. Meanwhile, there were 137 cases in medication group [118 were males and mean age (42±12) years]. The clearance rate of ureteral calculi at 24 h (67.88% vs 48.55%, P=0.001)、one week (76.64% vs 57.97%, P=0.001) and four weeks (89.05% vs 76.08%, P=0.005)after ESWL in medication group were significant higher than that in control group. There was a significant difference in the VAS score of pain scale after ESWL (1.77±0.80 vs 2.06±1.04, P=0.012) and re-ESWL rate (8.03% vs 17.39%,P=0.02) between two groups, but no difference with gross hematuria in 6 h after ESWL and drug allergy. Conclusions combination use of ketochromate tromethamine and phloroglucinol significantly improve early expulsion of ureteral calculi after ESWL in patients with distal ureteral calculi, with no side effect.

Genetic variations of Plasmodium falciparum circumsporozoite protein and the impact on interactions with human immunoproteins and malaria vaccine efficacy

In October 2021, the world's first malaria vaccine RTS,S was endorsed by WHO for broad use in children, despite its low efficacy. This study examined polyclonal infections and the associations of parasite genetic variations with binding affinity to human leukocyte antigen (HLA). Multiplicity of infection was determined by amplicon deep sequencing of PfMSP1. Genetic variations in PfCSP were examined across 88 samples from Ghana and analyzed together with 1655 PfCSP sequences from other African and non-African isolates. Binding interactions of PfCSP peptide variants and HLA were predicted using NetChop and HADDOCK. High polyclonality was detected among infections, with each infection harboring multiple non-3D7 PfCSP variants. Twenty-seven PfCSP haplotypes were detected in the Ghanaian samples, and they broadly represented PfCSP diversity across Africa. The number of genetic differences between 3D7 and non-3D7 PfCSP variants does not influence binding to HLA. However, CSP peptide length after proteolytic degradation significantly affects its molecular weight and binding affinity to HLA. Despite the high diversity of HLA, the majority of the HLAI and II alleles interacted/bound with all Ghana CSP peptides. Multiple non-3D7 strains among P. falciparum infections could impact the effectiveness of RTS,S. Longer peptides of the Th2R/Th3R CSP regions should be considered in future versions of RTS,S.

A simple alkali lysis method for Plasmodium falciparum DNA extraction from filter paper blood samples

A fast, simple, easy, efficient, and inexpensive method for DNA extraction from malaria parasites collected on filter paper would be very useful for molecular surveillance. The quality and quantity of DNA are critical to molecular diagnosis and analysis. Here, we developed a simple alkali lysis method for DNA extraction from blood samples on filter paper. The results showed that 10-50 mM NaOH and deionized water all effectively isolated parasite DNA at higher parasitemia, as witnessed by successful PCR amplification, while at a parasitemia of 0.01%, the 10 mM NaOH lysis condition generated the best results. Furthermore, DNA extracted by this method was successfully used to amplify a fragment of > 2000 bp. This method successfully extracted DNA from 1 µl of blood at a parasitemia as low as 0.0001% (equivalent to 5 parasites /µl). The DNA isolated by the 10 mM NaOH lysis method was stable to yield PCR products after storage at 4 °C or - 20 °C for 12 months. These results indicate that this alkali lysis method is simple, effective, sensitive, and inexpensive for isolating stable Plasmodium DNA from dried blood spots on filter paper.

Spatio-temporal trends of malaria incidence from 2011 to 2017 and environmental predictors of malaria transmission in Myanmar

BACKGROUND

Myanmar bears the heaviest malaria burden in the Greater Mekong Subregion (GMS). This study assessed the spatio-temporal dynamics and environmental predictors of Plasmodium falciparum and Plasmodium vivax malaria in Myanmar.

METHODS

Monthly reports of malaria cases at primary health centers during 2011-2017 were analyzed to describe malaria distribution across Myanmar at the township and state/region levels by spatial autocorrelation (Moran index) and spatio-temporal clustering. Negative binomial generalized additive models identified environmental predictors for falciparum and vivax malaria, respectively.

RESULTS

From 2011 to 2017, there was an apparent reduction in malaria incidence in Myanmar. Malaria incidence peaked in June each year. There were significant spatial autocorrelation and clustering with extreme spatial heterogeneity in malaria cases and test positivity across the nation (P < 0.05). Areas with higher malaria incidence were concentrated along international borders. Primary clusters of P. falciparum persisted in western townships, while clusters of P. vivax shifted geographically over the study period. The primary cluster was detected from January 2011 to December 2013 and covered two states (Sagaing and Kachin). Annual malaria incidence was highest in townships with a mean elevation of 500‒600 m and a high variance in elevation (states with both high and low elevation). There was an apparent linear relationship between the mean normalized difference vegetative index and annual P. falciparum incidence (P < 0.05).

CONCLUSION

The decreasing trends reflect the significant achievement of malaria control efforts in Myanmar. Prioritizing the allocation of resources to high-risk areas identified in this study can achieve effective disease control.

Transmission efficiency of Plasmodium vivax at low parasitaemia

BACKGROUND

Plasmodium vivax is responsible for much of malaria outside Africa. Although most P. vivax infections in endemic areas are asymptomatic and have low parasite densities, they are considered a potentially important source of transmission. Several studies have demonstrated that asymptomatic P. vivax carriers can transmit the parasite to mosquitoes, but the efficiency has not been well quantified. The aim of this study is to determine the relationship between parasite density and mosquito infectivity, particularly at low parasitaemia.

METHODS

Membrane feeding assays were performed using serial dilutions of P. vivax-infected blood to define the relationship between parasitaemia and mosquito infectivity.

RESULTS

The infection rate (oocyst prevalence) and intensity (oocyst load) were positively correlated with the parasite density in the blood. There was a broad case-to-case variation in parasite infectivity. The geometric mean parasite density yielding a 10% mosquito infection rate was 33 (CI 95 9-120) parasites/µl or 4 (CI 95 1-17) gametocytes/µl. The geometric mean parasite density yielding a 50% mosquito infection rate was 146 (CI 95 36-586) parasites/µl or 13 (CI 95 3-49) gametocytes/µl.

CONCLUSION

This study quantified the ability of P. vivax to infect Anopheles dirus at over a broad range of parasite densities. It provides important information about parasite infectivity at low parasitaemia common among asymptomatic P. vivax carriers.

Community acceptability, participation, and adherence to mass drug administration with primaquine for Plasmodium vivax elimination in Southern Thailand: a mixed methods approach

BACKGROUND

Mass drug administration (MDA) with primaquine (PQ) is being considered for accelerating Plasmodium vivax elimination in remaining active foci. This study aimed to determine the acceptability of MDA with PQ in malaria endemic villages in a malarious setting in the South of Thailand undergoing MDA with PQ.

METHODS

A cross-sectional mixed-methods approach was conducted in seven malaria endemic villages where MDA with PQ was implemented. The data were collected from community villagers and health workers using structured questionnaires, in-depth interviews, and focus group discussions. Descriptive statistics and logistic regression models were used for quantitative data analysis. Thematic analysis was applied for qualitative data.

RESULTS

Among a total of 469 participants from the MDA villages, 293 participants were eligible for MDA with PQ and 79.86% (234) completed 14-days of PQ. The logistic regressions indicated that males (adjusted odds ratio: 2.52 [95% confidence interval: 1.33-4.81]) and those who are farmers (2.57 [1.12-5.90]) were most likely to participate in the MDA. Among 293 participants in the post-MDA study, 74.06% had originally agreed to participate in the MDA with PQ while 25.94% had originally reported not wanting to participate in the MDA. Of those who originally reported being willing to participate in the MDA, 71.23% followed through with participation in the first or second round. Conversely, 93.24% of those who originally reported not being willing to participate in the MDA did in fact participate in the MDA. Factors contributing to higher odds of agreeing to participate and following through with participation included being male (1.98 [1.06-3.69]) and correctly responding that malaria is preventable (2.32 [1.01-5.35]) with some differences by village. Five key themes emerged from the qualitative analyses: concern about side effects from taking PQ; disbelief that malaria could be eliminated in this setting; low overall concern about malaria infections; misunderstandings about malaria; and a general need to tailor public health efforts for this unique context.

CONCLUSION

While the reported likelihood of participating in MDA was high in this setting, actual follow-through was relatively moderate, partially because of eligibility (roughly 71% of those in the follow-up survey who originally agreed to participate actually followed through with participation). One of the largest concerns among study participants was PQ-related side effects-and these concerns likely heavily influenced participant adherence to the MDA. The results of this study can be used to tailor future MDAs, or other public health interventions, in this and potentially other similar settings.