Progress and impact of 13 years of the global programme to eliminate lymphatic filariasis on reducing the burden of filarial disease

Deciphering the pH-dependent oligomerization of aspartate semialdehyde dehydrogenase from Wolbachia endosymbiont of Brugia malayi: An in vitro and in silico approaches

The enzyme aspartate semialdehyde dehydrogenase (ASDH) plays a pivotal role in the amino acid biosynthesis pathway, making it an attractive target for the development of new antimicrobial drugs due to its absence in humans. This study aims to investigate the presence of ASDH in the filarial parasite Wolbachia endosymbiont of Brugia malayi (WBm) using both in vitro and in silico approaches. The size exclusion chromatography (SEC) and Native-PAGE analysis demonstrate that WBm-ASDH undergoes pH-dependent oligomerization and dimerization. To gain a deeper understanding of this phenomenon, the modelled monomer and dimer structures were subjected to pH-dependent dynamics simulations in various conditions. The results reveal that residues Val240, Gln161, Thr159, Tyr160, and Trp316 form strong hydrogen bond contacts in the intersurface area to maintain the structure in the dimeric form. Furthermore, the binding of NADP+ induces conformational changes, leading to an open or closed conformation in the structure. Importantly, the binding of NADP+ does not disturb either the dimerization or oligomerization of the protein, a finding confirmed through both in vitro and in silico analysis. These findings shed light on the structural characteristics of WBm-ASDH and offer valuable insights for the development of new inhibitors specific to WBm, thereby contributing to the development of potential therapies for filarial parasitic infections.

'The Lost Peace': Evidencing the Syndemic Relationship between Neglected Tropical Diseases and Mental Distress in Liberia

Neglected Tropical Diseases (NTDs) are a group of chronic infectious diseases of poverty affecting over one billion people globally. Intersections of NTDs, disability, and mental ill-health are increasingly evidenced but are rarely studied from a mixed-methods perspective. Here, we advance syndemic understandings by further assessing and contextualising the syndemic relationship between NTDs (particularly their associated disability) and mental distress in Liberia. Participatory qualitative methods, including body mapping (56 participants), social mapping (28 participants), and in-depth interviews (12) provided space for persons affected by NTDs to narrate their experiences. Simultaneously, 201 surveys explored experiences of common mental health conditions among persons affected by skin NTDs. An intersectionality approach was applied within the analysis for both qualitative and quantitative methods informed by Meyer's minority stress model, adapted for NTDs. Qualitative data was analysed thematically and gender-disaggregated, univariable and multivariable analyses were applied to survey data for the outcome measures depression (PHQ-9) and anxiety (GAD-7). Disability was associated with higher levels of depression and anxiety (p < 0.001). An interaction between disability and being a women increased incidence risk ratio of depression (p < 0.001). In alignment with qualitative findings, persons affected experienced additional generalised (financial concerns), external (experience of stigma) and internal (experience of pain and physical symptoms) minority stressors, to varying degrees, which contributed towards their mental distress, and mental health conditions. These findings were used to co-develop a syndemic-informed person-centred health system response to address the suffering associated with NTDs and mental distress, including a focus on strengthening relationships between formal and informal community health actors and the broader health system.

The impact of the National Programme to Eliminate Lymphatic Filariasis on filariasis morbidity in Sri Lanka: Comparison of current status with retrospective data following the elimination of lymphatic filariasis as a public health problem

INTRODUCTION

Sri Lanka implemented the National Programme for Elimination of Lymphatic Filariasis (NPELF) in its endemic regions in 2002. Five annual rounds of mass drug administration using the two-drug combination diethylcarbamazine (DEC) and albendazole led to sustained reductions in infection rates below threshold levels. In 2016, WHO validated that Sri Lanka eliminated lymphatic filariasis as a public health problem.

OBJECTIVE

To explore the impact of the NPELF on lymphatic filariasis morbidity in Sri Lanka.

METHODS

Passive Case Detection (PCD) data maintained in filaria clinic registries from 2006-2022 for lymphoedema and hospital admission data for managing hydroceles/spermatoceles from 2007-2022 were analyzed. The morbidity status in 2022 and trends in overall and district-wise PCD rates were assessed. Poisson log-linear models were used to assess the trends in PCD for endemic regions, including district-wise trends and hospital admissions for the management of hydroceles/spermatoceles.

RESULTS

In 2022, there were 566 new lymphoedema case visits. The mean (SD) age was 53.9 (16.0) years. The staging was done for 94% of cases, of which 79% were in the early stages (57.3% and 21.4% in stages two and one, respectively). Western Province had the highest caseload (52%), followed by the Southern (32%) and Northwestern (16%) Provinces, respectively. The reported lymphoedema PCD rate in 2022 was 0.61 per 10,000 endemic population. The overall PCD rate showed a decline of 7.6% (95%CI: 4.9% - 10.3%) per year (P < 0.0001) from 2007 to 2022. A steady decline was observed in Colombo, Gampaha and Kurunegala districts, while Kalutara remained static and other districts showed a decline in recent years. Further, admissions for inpatient management of hydroceles/spermatoceles showed a declining trend after 2015.

CONCLUSIONS

The PCD rates of lymphoedema and hydroceles/spermatoceles showed a declining trend in Sri Lanka after the implementation of the NPELF.

Addressing the Syndemic Relationship between Lymphatic Filariasis and Mental Distress in Malawi: The Potential of Enhanced Self-Care

Lymphatic filariasis (LF) causes disfiguring and disabling lymphoedema, which can lead to mental distress and requires life-long self-care treatment. This study applies syndemic theory to understand the biosocial relationship between LF and mental distress in Malawi. Using in-depth qualitative methods, we critically evaluate experiences of mental distress and LF through 21 life-history interviews, to narrate experiences from the perspective of persons affected by LF, and to understand how enhanced self-care (ESC) for lymphoedema management disrupts the syndemic relationship. Complementary key informant interviews with Ministry of Health LF programme staff were conducted to further understand intervention and health system delivery. All interviews were recorded, transcribed, and translated, and then subject to thematic analysis. Our findings suggest that for persons affected by LF in Malawi, before being trained in ESC, absent referral pathways, inequalities in healthcare provision or available treatment, and limited knowledge of the condition (LF) drove the syndemic of LF and mental distress. Distress was often exacerbated by stigma and social exclusion, and shaped by intersections of gender, generation, poverty, and extreme climate conditions. We argue that addressing the syndemic suffering associated with LF and mental distress through interventions which center the needs of persons affected is critical in effective and equitable LF care delivery.

Prevalence of zoonotic (brugian) filariasis in Asia: A proportional meta-analysis

Lymphatic filariasis is a public health problem and targeted for global elimination. WHO recommends mass drug administration to interrupt transmission of the parasites involved. There are concerns that transmission interruption may be difficult in areas of zoonotic filarial infections. This study aimed to estimate the pooled prevalence of zoonotic brugian filariasis, and to compare the pooled prevalence of brugian filariasis in human and animal populations in the same area based on available studies. A comprehensive literature search was conducted in health-related electronic databases (PubMed, Ovid MEDLINE, Index Medicus, google scholar). A random-effect meta-analysis of the pooled overall prevalence of filariasis in animal populations was conducted. Sixteen studies from four different Asian countries were identified. Studies were conducted most frequently in Thailand (n = 7), followed by Malaysia (n = 5), India (n = 3), and Sri Lanka (n = 1). Regardless of animal group, the pooled overall prevalence of animal Brugia infections was 13% (95%CI: 7-21%, I2:98%, 16 studies). On stratification, the pooled overall prevalence in the animal population was 19% (95%CI: 1-50%, I2: 99%, 3 studies) in India, 8% (95%CI: 2-7%, I2: 97%, 5 studies) in Malaysia, and 13% (95%CI: 7-20%, I2: 94%, 7 studies) in Thailand. The prevalence in the animal population was 17% (95%CI: 13-21%, 1 study) in Sri Lanka. The pooled overall prevalence of Brugia malayi was 13% (95%CI: 7-21%, I2:98%, 12 studies), while for Brugia pahangi this was 12% (95%CI: 7-19%, I2:86%, 7 studies). Regardless of animal group, geographic area, or diagnostic test, the prevalence of B. malayi was consistently high. On stratification by animal category, the pooled overall prevalence was 10% (95%CI: 6-14%, I2:92%, 13 studies) in cats, 12% (95%CI: 2-28%, I2: 99%, 6 studies) in dogs, and 55% (95%CI: 47-63%, 1 study) in leaf-eating monkeys. The findings show the extent of zoonotic Brugiainfections in domestic cats and dogs, suggesting that these animals are potential reservoirs for human brugian filariasis in the study countries. To substantiate this with more accuracy, future well designed whole genomic sequencing of individual mf collected from humans and B. malayi infected animals in the same area are needed.

Entomological assessment in 'hotspots' of four lymphatic filariasis endemic districts, Central Nepal during post-MDA surveillance

BACKGROUND OBJECTIVES

Annual mass drug administration (MDA) is the main strategy to interrupt the transmission of lymphatic filariasis (LF) in the community. The main aim of monitoring the MDA program, for its effectiveness and interruption of LF is the post-MDA surveillance using antigen survey in children born after MDA. The latest technique of new research suggests that xenomonitoring is an effective tool for monitoring LF intervention. The objective of this study was to assess the W. bancrofti infection/or infectivity in vector mosquitoes by xenomonitoring during post-MDA surveillance.

METHODS

A descriptive cross-sectional study was conducted in the hotspots of selected four districts of Central Nepal. A gravid trap technique was used for sampling mosquitoes. Infection/or infectivity was determined via the dissection of vector mosquitoes. Anopheles, Aedes, Armigerus and Culex species were collected from hotspots of four endemic districts, two from the hilly region (Lalitpur and Dhading) and two from Terai region (Bara and Mahottari) of Central Nepal.

RESULTS

A total of 4450 mosquitoes belonging to four genera, Anopheles, Culex, Armigeres, and Aedes were collected from four hotspots. The distribution of Culex quinquefasciatus was found to be the highest, 88.9% (n=3955/4450) followed by Cx. vishnui (4.5%), Armigeres sp (5.8%), An. culicifascies (0.2%), Aedes spp (0.8%). The proportion of female mosquitoes trapped is significantly higher. A total of 3344 parous Cx. quinquefasciatus mosquitoes were dissected for any larval stage of W. bancrofti. We could not find any filarial infection in dissected mosquito samples.

INTERPRETATION CONCLUSION

We conclude that the gravid trap is an efficient tool for the collection of gravid Cx. quinquefasciatus mosquitoes for xenomonitoring studies of filariasis endemic regions. Vector composition indicated a maximum number of vector mosquitoes of lymphatic filariasis were trapped compared with the other three species. Distribution and density of Cx. quinquefasciatus was found highest in four hotspots of endemic districts. None of the Cx. quinquefasciatus dissected were found to be infected by larval forms of filaria. Since the low levels of infection persistence in the human population in these hot spots, vector infection and infectivity can't be ignored. Microscopic xenomonitoring at a low level of infection persistent is less likely to be efficient so molecular xenomonitoring along with a large sample should be required in each of the hot spots of the districts. Additionally, area is receptive so further vector control intervention should be required to reduce the risk of resurgence of infection.

Comparative Safety Surveillance of Triple (IDA) Versus Dual Therapy (DA) in Mass Drug Administration for Elimination of Lymphatic Filariasis in Kenya: A Cohort Event Monitoring Study

INTRODUCTION

Dual diethylcarbamazine and albendazole (DA) therapy is the standard mass drug administration (MDA) regimen for lymphatic filariasis in Kenya. Following the recent World Health Organization recommendation, Kenya piloted triple therapy with ivermectin, diethylcarbamazine, and albendazole (IDA) in MDA.

OBJECTIVE

We conducted a community-based, observational, cohort event monitoring study to compare the types, frequency, severity, and predictors of adverse events following dual versus triple therapy in 20,421 eligible residents.

METHODS

Residents in Kilifi (n = 10,010) and Mombasa counties (n = 10,411) received DA and IDA through MDA campaigns, respectively. Adverse events were actively monitored through house-to-house visits on days 1, 2, and 7 after MDA. Any clinical events reported before and after MDA were cross-checked and verified to differentiate pre-existing events from MDA-associated adverse events.

RESULTS

Overall, 5807 and 3102 adverse events were reported by 2839 and 1621 individuals in the IDA and DA groups, respectively. The incidence of experiencing one or more adverse events was significantly higher (p < 0.0001) in the IDA group (27.3%; 95% confidence interval [CI] 26.4-28.2) than in the DA group (16.2%; 95% CI 15.5-16.9). Dizziness (15.9% vs 5.9%) and drowsiness (10.1% vs 2.6%) were the most common adverse events and significantly higher in the IDA group compared with the DA group (p < 0.0001). Most adverse events were mild or moderate with a few severe cases (IDA = 0.05%; 95% CI 0.35-0.78, DA = 0.03%; 95% CI 0.14-0.60). Female sex, obesity, taking three or more diethylcarbamazine or ivermectin tablets, and having pre-existing clinical symptoms were significant predictors of adverse events following IDA treatment.

CONCLUSIONS

Ivermectin, diethylcarbamazine, and albendazole as a combination is as safe and well tolerated as DA to use in MDA campaigns with no serious life-threatening adverse events. Systemic mild-to-moderate adverse events with a few severe cases and transient adverse events are more common with IDA treatment than with DA treatment. Hence, integrating pharmacovigilance into a MDA program is recommended for the timely detection and management of adverse events.

Approach to the Patient with Non-cardiac Leg Swelling

One of the most common reasons for patient visits in the outpatient practice is lower extremity swelling. Non-cardiac etiologies are the most frequent reason for these encounters. The approach to this patient population will focus on the 7 key questions to initiate the gathering of historical information on the etiology of leg swelling. Figures and tables will complement the text for diagnosing lower extremity swelling. In this article, the common non-cardiac etiologies will be reviewed which include medications, chronic venous insufficiency, lymphatic disease, lipedema, venous thrombosis, and musculoskeletal etiologies.

Spatial predictive risk mapping of lymphatic filariasis residual hotspots in American Samoa using demographic and environmental factors

BACKGROUND

American Samoa successfully completed seven rounds of mass drug administration (MDA) for lymphatic filariasis (LF) from 2000-2006. The territory passed the school-based transmission assessment surveys in 2011 and 2015 but failed in 2016. One of the key challenges after the implementation of MDA is the identification of any residual hotspots of transmission.

METHOD

Based on data collected in a 2016 community survey in persons aged ≥8 years, Bayesian geostatistical models were developed for LF antigen (Ag), and Wb123, Bm14, Bm33 antibodies (Abs) to predict spatial variation in infection markers using demographic and environmental factors (including land cover, elevation, rainfall, distance to the coastline and distance to streams).

RESULTS

In the Ag model, females had a 26.8% (95% CrI: 11.0-39.8%) lower risk of being Ag-positive than males. There was a 2.4% (95% CrI: 1.8-3.0%) increase in the odds of Ag positivity for every year of age. Also, the odds of Ag-positivity increased by 0.4% (95% CrI: 0.1-0.7%) for each 1% increase in tree cover. The models for Wb123, Bm14 and Bm33 Abs showed similar significant associations as the Ag model for sex, age and tree coverage. After accounting for the effect of covariates, the radii of the clusters were larger for Bm14 and Bm33 Abs compared to Ag and Wb123 Ab. The predictive maps showed that Ab-positivity was more widespread across the territory, while Ag-positivity was more confined to villages in the north-west of the main island.

CONCLUSION

The findings may facilitate more specific targeting of post-MDA surveillance activities by prioritising those areas at higher risk of ongoing transmission.

Lymphatic Filariasis Elimination Status: Wuchereria bancrofti Infections in Human Populations after Five Effective Rounds of Mass Drug Administration in Zambia

Lymphatic filariasis (LF), also commonly known as elephantiasis, is a neglected tropical disease (NTD) caused by filarial parasites. The disease is transmitted via a bite from infected mosquitoes. The bites of these infected mosquitoes deposit filarial parasites, Wuchereria or Brugia, whose predilection site is the lymphatic system. The damage to the lymph system causes swelling in the legs, arms, and genitalia. A mapping survey conducted between 2003 and 2011 determined LF as being endemic in Zambia in 96 out of 116 districts. Elimination of LF is known to be possible by stopping the spread of the infection through large-scale preventive chemotherapy. Therefore, mass drug administration (MDA) with diethylcarbamazine citrate (DEC) (6 mg/kg) and Albendazole (400 mg) for Zambia has been conducted and implemented in all endemic districts with five effective rounds. In order to determine whether LF prevalence has been sufficiently reduced to levels less than 2% antigenemia and less than 1% microfilaremia, a pre-transmission assessment survey (pre-TAS) was conducted. Therefore, post-MDA pre-TAS was conducted between 2021 and 2022 in 80 districts to determine the LF prevalence. We conducted a cross-sectional seroprevalence study involving 600 participants in each evaluation unit (EU) or each district. The study sites (sentinel and spot-check sites) were from districts that were the implementation units (IUs) of the LF MDA. These included 80 districts from the 9 provinces. A total of 47,235 people from sentinel and spot-check locations were tested. Of these, valid tests were 47,052, of which 27,762 (59%) were females and 19,290 (41%) were males. The survey revealed in the 79/80 endemic districts a prevalence of Wb antigens of 0.14% and 0.0% prevalence of microfilariae. All the surveyed districts had an optimum prevalence of less than 2% for antigenaemia, except for Chibombo district. The majority of participants that tested positive for Wuchereria bancrofti (Wb) Antigens (Ag) were those that had 2, 3, and 4 rounds of MDA. Surprisingly, individuals that had 1 round of MDA were not found to have circulating antigens of Wb. The study showed that all the surveyed districts, except for Chibombo, passed pre-TAS. This further implies that there is a need to conduct transmission assessment surveys (TASs) in these districts.

Lymphatic filariasis endgame strategies: Using GEOFIL to model mass drug administration and targeted surveillance and treatment strategies in American Samoa

American Samoa underwent seven rounds of mass drug administration (MDA) for lymphatic filariasis (LF) from 2000-2006, but subsequent surveys found evidence of ongoing transmission. American Samoa has since undergone further rounds of MDA in 2018, 2019, and 2021; however, recent surveys indicate that transmission is still ongoing. GEOFIL, a spatially-explicit agent-based LF model, was used to compare the effectiveness of territory-wide triple-drug MDA (3D-MDA) with targeted surveillance and treatment strategies. Both approaches relied on treatment with ivermectin, diethylcarbamazine, and albendazole. We simulated three levels of whole population coverage for 3D-MDA: 65%, 73%, and 85%, while the targeted strategies relied on surveillance in schools, workplaces, and households, followed by targeted treatment. In the household-based strategies, we simulated 1-5 teams travelling village-to-village and offering antigen (Ag) testing to randomly selected households in each village. If an Ag-positive person was identified, treatment was offered to members of all households within 100m-1km of the positive case. All simulated interventions were finished by 2027 and their effectiveness was judged by their 'control probability'-the proportion of simulations in which microfilariae prevalence decreased between 2030 and 2035. Without future intervention, we predict Ag prevalence will rebound. With 3D-MDA, a 90% control probability required an estimated ≥ 4 further rounds with 65% coverage, ≥ 3 rounds with 73% coverage, or ≥ 2 rounds with 85% coverage. While household-based strategies were substantially more testing-intensive than 3D-MDA, they could offer comparable control probabilities with substantially fewer treatments; e.g. three teams aiming to test 50% of households and offering treatment to a 500m radius had approximately the same control probability as three rounds of 73% 3D-MDA, but used < 40% the number of treatments. School- and workplace-based interventions proved ineffective. Regardless of strategy, reducing Ag prevalence below the 1% target threshold recommended by the World Health Organization was a poor indicator of the interruption of LF transmission, highlighting the need to review blanket elimination targets.

Understanding key vectors and vector-borne diseases associated with freshwater ecosystem across Africa: Implications for public health

The emerging and re-emerging vector-borne diseases transmitted by key freshwater organisms have remained a global concern. As one of the leading biodiversity hotspots, the African ecoregion is suggested to harbour the highest number of freshwater organisms globally. Among the commonly found organisms in the African ecoregion are mosquitoes and snails, with a majority of their life cycle in freshwater, and these freshwater organisms can transmit diseases or serve as carriers of devastating diseases of public health concerns. However, synthetic studies to link the evident abundant presence and wide distribution of these vectors across the freshwater ecosystems in Africa with the increasing emerging and re-emerging vector-borne diseases in Africa are still limited. Here, we reviewed documented evidence on vector-borne diseases and their transmission pathways in Africa to reduce the knowledge gap on the factors influencing the increasing emerging and re-emerging vector-borne diseases across Africa. We found the population distributions or abundance of these freshwater organisms to be increasing, which is directly associated with the increasing emerging and re-emerging vector-borne diseases across Africa. Furthermore, we found that although the current changing environmental conditions in Africa affect the habitats of these freshwater organisms, current changing environmental conditions may not be suppressing the population distributions or abundance of these freshwater organisms. Instead, we found that these freshwater organisms are extending their geographic ranges across Africa, which may have significant public health implications in Africa. Thus, our study demonstrates the need for future studies to integrate the environmental conditions of vectors' habitats to understand if these environmental conditions directly or indirectly influence the vectorial capacities and transmission abilities of vectors of diseases. We propose that such studies will be necessary to guide policymakers in making informed policies to help control vector-borne diseases.

Increased HIV Incidence in Wuchereria bancrofti Microfilaria Positive Individuals in Tanzania

Background: Infections with Wuchereria bancrofti are associated with reduced immunity against concomitant infections. Indeed, our previous study described a 2.3-fold increased HIV incidence among individuals with W. bancrofti infection, as measured by the circulating filarial antigen of the adult worm. This new study aimed to retrospectively determine microfilariae status of the participants to assess if the previously described increased HIV susceptibility was associated with the presence of MF in the same cohort. Methods: CFA positive but HIV negative biobanked human blood samples (n = 350) were analyzed for W. bancrofti MF chitinase using real time PCR. Results: The PCR provided a positive signal in 12/350 (3.4%) samples. During four years of follow-up (1109 person years (PY)), 22 study participants acquired an HIV infection. In 39 PY of W. bancrofti MF chitinase positive individuals, three new HIV infections occurred (7.8 cases per 100 PY), in contrast to 19 seroconversions in 1070 PY of W. bancrofti MF chitinase negative individuals (1.8 cases per 100 PY, p = 0.014). Conclusions: In the subgroup of MF-producing Wb-infected individuals, the HIV incidence exceeded the previously described moderate increased risk for HIV seen in all Wb-infected individuals (regardless of MF status) compared with uninfected persons from the same area.

Wbm0076, a candidate effector protein of the Wolbachia endosymbiont of Brugia malayi, disrupts eukaryotic actin dynamics

Brugia malayi, a parasitic roundworm of humans, is colonized by the obligate intracellular bacterium, Wolbachia pipientis. The symbiosis between this nematode and bacterium is essential for nematode reproduction and long-term survival in a human host. Therefore, identifying molecular mechanisms required by Wolbachia to persist in and colonize B. malayi tissues will provide new essential information regarding the basic biology of this endosymbiosis. Wolbachia utilize a Type IV secretion system to translocate so-called "effector" proteins into the cytosol of B. malayi cells to promote colonization of the eukaryotic host. However, the characterization of these Wolbachia secreted proteins has remained elusive due to the genetic intractability of both organisms. Strikingly, expression of the candidate Wolbachia Type IV-secreted effector protein, Wbm0076, in the surrogate eukaryotic cell model, Saccharomyces cerevisiae, resulted in the disruption of the yeast actin cytoskeleton and inhibition of endocytosis. Genetic analyses show that Wbm0076 is a member of the family of Wiskott-Aldrich syndrome proteins (WAS [p]), a well-conserved eukaryotic protein family required for the organization of actin skeletal structures. Thus, Wbm0076 likely plays a central role in the active cell-to-cell movement of Wolbachia throughout B. malayi tissues during nematode development. As most Wolbachia isolates sequenced to date encode at least partial orthologs of wBm0076, we find it likely that the ability of Wolbachia to directly manipulate host actin dynamics is an essential requirement of all Wolbachia endosymbioses, independent of host cell species.

Description of potential vectors of zoonotic filarial nematodes, Brugia pahangi, Setaria digitata, and Setaria labiatopapillosa in Thai mosquitoes

Filariasis is classified as a vector-borne zoonotic disease caused by several filarial nematodes. The disease is widely distributed in tropical and subtropical regions. Understanding the relationship between mosquito vectors, filarial parasites, and vertebrate hosts is therefore essential for determining the probability of disease transmission and, correspondingly, developing effective strategies for prevention and control of diseases. In this study, we aimed to investigate the infection of zoonotic filarial nematodes in field-caught mosquitoes, observe the potential vectors of filaria parasites in Thailand using a molecular-based survey, conduct a study of host-parasite relationship, and propose possible coevolution of the parasites and their hosts. Mosquitoes were collected around cattle farms in Bangkok, Nakhon Si Thammarat, Ratchaburi, and Lampang provinces from May to December 2021 using a CDC Backpack aspirator for 20-30 minutes in each area (intra-, peri-, and wild environment). All mosquitoes were identified and morphologically dissected to demonstrate the live larvae of the filarial nematode. Furthermore, all samples were tested for filarial infections using PCR and sequencing. A total of 1,273 adult female mosquitoes consisted of five species: 37.78% Culex quinquefasciatus, 22.47% Armigeres subalbatus, 4.71% Cx. tritaeniorhynchus, 19.72% Anopheles peditaeniatus, and 15.32% An. dirus. Larvae of Brugia pahangi and Setaria labiatopapillosa were found in Ar. subalbatus and An. dirus mosquitoes, respectively. All mosquito samples were processed by PCR of ITS1 and COXI genes for filaria nematode species identification. Both genes showed that B. pahangi was found in four mosquitoes of Ar. subalbatus from Nakhon Si Thammarat, S. digitata was detected in three samples of An. peditaeniatus from Lampang, and S. labiatopapillosa was detected in one of An. dirus from Ratchaburi. However, filarial nematodes were not found in all Culex species. This study infers that this is the first data regarding the circulation of Setaria parasites in Anopheles spp. from Thailand. The phylogenetic trees of the hosts and parasites are congruent. Moreover, the data could be used to develop more effective prevention and control strategies for zoonotic filarial nematodes before they spread in Thailand.

Overview of Lymphedema for Physicians and Other Clinicians: A Review of Fundamental Concepts

Lymphedema has historically been underrated in clinical practice, education, and scholarship to the detriment of many patients with this chronic, debilitating condition. The mechanical insufficiency of the lymphatic system causes the abnormal accumulation of protein-rich fluid in the interstitium, which triggers a cascade of adverse consequences such as fat deposition and fibrosis. As the condition progresses, patients present with extremity heaviness, itchiness, skin infections, and, in later stages, dermal fibrosis, skin papillomas, acanthosis, and other trophic skin changes. Correspondingly, lymphedema results in psychological morbidity, including anxiety, depression, social avoidance, and a decreased quality of life, encompassing emotional, functional, physical, and social domains. For this review, we conducted a literature search using PubMed and EMBASE and herein summarize the evidence related to the fundamental concepts of lymphedema. This article aims to raise awareness of this serious condition and outline and review the fundamental concepts of lymphedema.

A Comparative Study of Lymphatic Filariasis-Related Perceptions among Treated and Non-Treated Individuals in the Ahanta West Municipality of Ghana

Background: Ghana joined the Global Programme to Eliminate Lymphatic Filariasis (GPELF), established in the year 2000, with the aim of eliminating the disease as a public health problem through annual mass treatment of entire endemic populations. Since 2001, the country has implemented mass drug administration (MDA) in endemic districts, with great reductions in the population at risk for infection. However, in many districts, the elimination programme is faced with the presence of hotspots, which may be due in part to individuals not taking part in MDA (either intentionally or unintentionally) who may serve as reservoirs to sustain transmission. This paper compares the LF-related perceptions among individuals who regularly take the MDA drugs and those who seldom or never take part in the MDA in the Ahanta West Municipality of Ghana to determine community acceptable ways to implement an intervention aimed to track, engage, and treat individuals who regularly miss MDA or to test individuals who intentionally refuse MDA and treat them if positive for LF. Methods: This was a mixed method study employing questionnaire surveys and focus group discussions (FDG) for data collection. Survey participants were randomly selected from the 2019 treatment register to stratify respondents into treated and non-treated groups. FGD participants were selected purposively such that there are at least two non-treated persons in each discussion session. Results: Over 90% of the respondents were aware of the disease. Poor hygiene/dirty environment was wrongly reported by most respondents (76.8%) as the causes. MDA awareness was very high among both treated (96.9%) and non-treated (98.6%) groups. A low sense of vulnerability to LF infection was evident by a reduction in the number of people presenting clinical manifestations of the disease in communities. Slightly more, 65 (29.0%) of the non-treated group compared to the 42 (19.4%) treated group reported ever experiencing adverse effects of the MDA drugs. Barriers to MDA uptake reported in both groups were poor planning and implementation of the MDA, lack of commitments on the part of drug distributors, and adverse drug reactions. About 51% of the non-treated group reported never taking the drugs even once in the last five years, while 61% among the treated group took the MDA drug consistently in the past five years. Respondents in both groups believed that, when engaged properly, most non-treated persons will accept to take the drug but insisted community drug distributors (CDDs) must be trained to effectively engage people and have time for those they will be engaging in dialogue. The chiefs emerged as the most influential people who can influence people to take MDA drugs. Conclusions: The reduction in risk perception among respondents, adverse reactions and the timing of MDA activities may be influencing MDA non-participation in the study area; however, respondents think that non-treated individuals will accept the interventions when engaged properly by the CDDs. This has been corrected and it now read “Respondents in both groups believed that, when community drug distributors (CDDs) are trained on how to engage the non-treated persons in effective dialogue, most of them will accept to take the drugs”.

Evaluating Molecular Xenomonitoring as a Tool for Lymphatic Filariasis Surveillance in Samoa, 2018-2019

Molecular xenomonitoring (MX), the detection of filarial DNA in mosquitoes using molecular methods (PCR), is a potentially useful surveillance strategy for lymphatic filariasis (LF) elimination programs. Delay in filarial antigen (Ag) clearance post-treatment is a limitation of using human surveys to provide an early indicator of the impact of mass drug administration (MDA), and MX may be more useful in this setting. We compared prevalence of infected mosquitoes pre- and post-MDA (2018 and 2019) in 35 primary sampling units (PSUs) in Samoa, and investigated associations between the presence of PCR-positive mosquitoes and Ag-positive humans. We observed a statistically significant decline in estimated mosquito infection prevalence post-MDA at the national level (from 0.9% to 0.3%, OR 0.4) but no change in human Ag prevalence during this time. Ag prevalence in 2019 was higher in randomly selected PSUs where PCR-positive pools were detected (1.4% in ages 5–9; 4.8% in ages ≥10), compared to those where PCR-positive pools were not detected (0.2% in ages 5–9; 3.2% in ages ≥10). Our study provides promising evidence for MX as a complement to human surveys in post-MDA surveillance.

Prevalence and management of filarial lymphoedema and its associated factors in Lindi district, Tanzania: A community-based cross-sectional study

OBJECTIVE

To determine the burden and management of filarial lymphoedema and its associated factors in Lindi district, Tanzania.

METHODS

Cross-sectional study involving 954 community members who were screened for filarial lymphoedema by using a checklist. Moreover, lymphoedema patients were examined for the presence of entry lesions, staging of disease, and interviewed on acute dermatolymphangioadenitis (ADLA) attacks, and their current practices on lymphoedema management. Descriptive statistics and logistic regression analyses were performed. A p < 0.05 was considered statistically significant.

RESULTS

The prevalence of filarial lymphoedema was 7.8%, with the majority in the early stage of lymphoedema (78.4%). The large majority (98.6%) of the patients had lower limb lymphoedema and 46% of lymphoedema patients had entry lesions. More than a half (60.8%) of those lymphoedema patients had experienced ADLA attacks; close to two-thirds (64.8%) had one or two attacks in the past 6 months. Generally, patients had inappropriate hygiene care practices for filarial lymphoedema management. Inappropriate hygiene care practice for lymphoedema management was associated with an increased risk for the development of advance stage of lymphoedema (adjusted odds ratio = 7.379, 95%, confidence interval: 3.535-16.018, p = 0.04).

CONCLUSION

Though lymphatic filariasis transmission has drastically declined, chronic manifestations of lymphoedema persist in Lindi district. The recommended disease management practices are deficient, which calls for a programmatic approach for mapping the burden of lymphoedema and implementing its management.

A refined and updated health impact assessment of the Global Programme to Eliminate Lymphatic Filariasis (2000-2020)

Background

Lymphatic filariasis (LF) is a neglected tropical disease (NTD). In 2000 the World Health Organization (WHO) established the Global Programme to Eliminate Lymphatic Filariasis (GPELF). A key component of this programme is mass drug administration (MDA). Between 2000 and 2020, the GPELF has delivered over 8.6 billion treatments to at-risk populations. The last impact assessment of the programme evaluated the treatments provided between 2000–2014. The goal of this analysis is to provide an updated health impact assessment of the programme, based on the numbers treated between 2000–2020.

Methods

We updated and refined a previously established model that estimates the number of clinical manifestations and disability-adjusted life years (DALYs) averted by the treatments provided by the GPELF. The model comprises three different population cohorts that can benefit from MDA provided (those protected from acquiring infection, those with subclinical morbidity prevented from progressing and those with clinical disease alleviated). The treatment numbers were updated for all participating countries using data from the WHO. In addition, data relating to the estimated number of individuals initially at risk of LF infection were updated where possible. Finally, the DALY calculations were refined to use updated disability weights.

Results

Using the updated model and corresponding treatment data, we projected that the total benefit cohort of the GPELF (2000–2020) would consist of approximately 58.5 million individuals and the programme would avert 44.3 million chronic LF cases. Over the lifetime of the benefit cohorts, this corresponded to 244 million DALYs being averted.

Conclusion

This study indicates that substantial health benefits have resulted from the first 20 years of the GPELF. It is important to note that the GPELF would have both additional benefits not quantified by the DALY burden metric as well as benefits on other co-endemic diseases (such as soil-transmitted helminths, onchocerciasis and scabies)—making the total health benefit underestimated. As with the past impact assessments, these results further justify the value and importance of continued investment in the GPELF.

Graphical Abstract

Bma-LAD-2, an Intestinal Cell Adhesion Protein, as a Potential Therapeutic Target for Lymphatic Filariasis

Lymphatic filariasis is a debilitating disease that afflicts over 70 million people worldwide. It is caused by the parasitic nematodes Wuchereria bancrofti, Brugia malayi, and Brugia timori. Despite substantial success, efforts to eliminate LF will likely require more time and resources than predicted. Identifying new drug and vaccine targets in adult filariae could help elimination efforts. This study’s aim was to evaluate intestinal proteins in adult Brugia malayi worms as possible therapeutic targets. Using short interfering RNA (siRNA), we successfully targeted four candidate gene transcripts: Bma-Serpin, Bma-ShTK, Bma-Reprolysin, and Bma-LAD-2. Of those, Bma-LAD-2, an immunoglobulin superfamily cell adhesion molecule (IgSF CAM), was determined to be essential for adult worm survival. We observed a 70.42% knockdown in Bma-LAD-2 transcript levels 1 day post-siRNA incubation and an 87.02% reduction in protein expression 2 days post-siRNA incubation. This inhibition of Bma-LAD-2 expression resulted in an 80% decrease in worm motility over 6 days, a 93.43% reduction in microfilaria release (Mf) by day 6 post-siRNA incubation, and a dramatic decrease in (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction. Transmission electron microscopy revealed the loss of microvilli and unraveling of mitochondrial cristae in the intestinal epithelium of Bma-LAD-2 siRNA-treated worms. Strikingly, Bma-LAD-2 siRNA-treated worms exhibited an almost complete loss of pseudocoelomic fluid. A luciferase immunoprecipitation system assay did not detect anti-Bma-LAD-2 IgE in the serum of 30 LF patients, indicating that LF exposure does not result in IgE sensitization to this antigen. These results indicate that Bma-LAD-2 is an essential protein for adult Brugia malayi and may be an effective therapeutic target.

Improving care for cancer-related and other forms of lymphoedema in low- and middle-income countries: a qualitative study

BACKGROUND

Lymphoedema is a common, distressing and debilitating condition that can be related to cancer and its treatment or other conditions. Little is known about current practices in the diagnosis, assessment and management of lymphoedema in low- and middle-income countries (LMIC).

AIM

To describe current practices in diagnosing, assessing and managing cancer-related and other forms of lymphoedema in LMIC, and related barriers and facilitators.

METHODS

An exploratory-descriptive qualitative study. Participants were lymphoedema experts or health care professionals identified via published lymphoedema papers and professional organizations respectively. Sampling was purposive to ensure a diversity of perspectives and experience. Data collection was via semi-structured telephone/video interviews, and questions canvassed participants' experiences and perceptions of lymphoedema care in LMIC. Interviews were audio-recorded and transcribed verbatim. Analysis proceeded via inductive coding before mapping codes to the World Health Organization's (WHO) Innovative Care for Chronic Conditions Framework.

RESULTS

Nineteen participants were interviewed, most of whom were physiotherapists (n = 11). Ten participants worked permanently in a LMIC, while the remainder were based in a high-income country (HIC) and had been involved in initiatives to improve lymphoedema care across multiple LMIC. Participants indicated that management of cancer versus non-cancer related lymphoedema was similar, but that pathways to care were more straight-forward for those receiving cancer care, leading to earlier diagnosis. Key facilitators to optimizing lymphoedema care in LMIC included: 1) joining forces to overcome lymphoedema-related stigma; 2) building workforce capabilities; and 3) partnering with patients and families to support self-management. Ideas for building workforce included developing health professional knowledge, supporting a commitment to multidisciplinary team care, and adapting HIC guidelines for lymphoedema care to LMIC. Partnering with patients and families to support self-management involved following the person-centred approach, establishing clear communication, promoting adherence to management, adapting management to available resources, and involving patient family and friends in lymphoedema care.

CONCLUSION

Raising community and health professional awareness regarding lymphoedema and its management is a key first step to improving care outcomes. Resources for clinicians and patients/families developed for lymphoedema care in HIC need to be adapted for low resource settings.

Mapping Spatial Variation and Impact of the National MDA Program on Lymphatic Filariasis Elimination in Ghana: An Initial Study

Lymphatic filariasis (LF) is a public health menace, especially in developing countries. A periodic review of mass drug administration (MDA) performance is critical to monitoring elimination progress. However, investigating the spatial pattern of LF with respect to MDA intervention is yet to be documented. This is essential to appreciating the transmission dynamics across LF-endemic communities and how it is spatially impacted by MDA programs. The aim of this study was to map and explore the spatial variation and hotspots of LF infection among endemic communities and evaluate the impact of the MDA intervention program on its spatial pattern in Ghana. Relative risks, clustering and clusters, prevalence odds ratios, and their confidence intervals were studied with community-level LF data prior to intervention and post intervention periods. The overall risk of LF infection was 0.12% and 0.02% before and after MDA, respectively, suggesting reduced transmission. Using empirical Bayesian smoothing to map the relative risk, a substantial variation in the spatial distribution of the relative risk of LF among endemic communities was observed. Most of the excess prevalence communities were unexpectedly visible even after years of MDA. The Empirical Bayesian Moran’s Index for global clustering showed a reduction in clustering of LF prevalence after MDA with IM = 0.455 and 0.119 for before and after MDA, respectively. Furthermore, examining risks associated with ecological zones, it was observed that the Guinea Savannah and the Transition Zone were the most vulnerable zones for LF infection with prevalence odds ratios 18.70- and 13.20-fold higher than in the reference Moist evergreen zone, respectively. We observed a drastic reduction in risk in the Wet evergreen zone after MDA, while the Guinea Savannah sustained high levels of risk even after MDA. These findings should prompt public health officials to adopt stratified cluster sampling in LF-endemic regions to monitor the rate and density of microfilaria.

Filarids (Spirurida: Onchocercidae) in wild carnivores and domestic dogs from the Brazilian Atlantic forest

Onchocercidae nematodes are heteroxenous parasites with worldwide distribution, and some of the species associated to animals may present zoonotic potential. Climatic changes and anthropic influences on the environment may result in vectors’ proliferation, facilitating the spillover to humans and/or non-typical animal hosts. The Iguaçu National Park (PARNA Iguaçu), one of the most important Brazilian natural remanescents of Atlantic rainforest, is strongly affected by human activities such as tourism and agriculture. The complexity of this area is especially characterized by the close nexus between the rich wildlife, humans, and domestic animals, especially domestic dogs. Based on this, this research aimed to diagnose the Onchocercidae nematodes in wild carnivores and domestic dogs in the PARNA Iguaçu and the surrounding areas. For this, we collected 162 samples of seven species of wild carnivores and 225 samples of domestic dogs. The presence of microfilariae in the blood samples was diagnosed by the modified Knott’s test and molecular screening, and the specific identification was based on sequencing of the myoHC and hsp70 genes. Microfilariae were detected only in ring-tailed coatis, in which we found five species: Mansonella sp. 1, Mansonela sp. 2, Onchocercidade gen. sp. 1, Onchocercidade gen. sp. 2, and Dirofilaria immitis. The morphological analysis supported the molecular findings. The domestic dogs were parasitized by Acanthocheilonema reconditum, representing a new locality record for this species. Phylogenetic analysis showed high genetic similarity among the four undetermined species and Mansonella spp., Brugia spp., and Wuchereria bancrofti. The presence of D. immitis in ring-tailed coatis may be result of spillover from dogs, even though the parasite was not diagnosed in the sampled dogs. The presence of several undetermined Onchocercidae species indicates the necessity of continuous investigations on wild and domestic animals from Neotropical area, especially considering the growing anthropic influence on forest remnants.

Filarids are vector-borne Onchocercidae nematodes widely distributed around the world, related to several hosts, both wild and domestic, in different Biomes, including human-related species. In consequence to deforestation, environmental degradation, and climate changes, there has been an expansion in the distribution of vector-borne diseases around the world, such as those caused by filarids, in endemic tropical areas and even in temperate regions where they did not used to occur before. Thus, epidemiology and molecular genetic diversity studies of these filarial parasites are of great importance for three main reasons: zoonotic potential of many known species of filarids; the lack of data about the species inhabiting neotropical regions and the current worldwide deforestation and consequent habitat loss scenario, which favors the emergence or re-emergence of diseases resulting from the infection of domestic animals and humans by parasites that used to have as reservoirs only wild animals.

Lymphatic filariasis in 2016 in American Samoa: Identifying clustering and hotspots using non-spatial and three spatial analytical methods

BACKGROUND

American Samoa completed seven rounds of mass drug administration from 2000-2006 as part of the Global Programme to Eliminate Lymphatic Filariasis (LF). However, resurgence was confirmed in 2016 through WHO-recommended school-based transmission assessment survey and a community-based survey. This paper uses data from the 2016 community survey to compare different spatial and non-spatial methods to characterise clustering and hotspots of LF.

METHOD

Non-spatial clustering of infection markers (antigen [Ag], microfilaraemia [Mf], and antibodies (Ab [Wb123, Bm14, Bm33]) was assessed using intra-cluster correlation coefficients (ICC) at household and village levels. Spatial dependence, clustering and hotspots were examined using semivariograms, Kulldorf's scan statistic and Getis-Ord Gi* statistics based on locations of surveyed households.

RESULTS

The survey included 2671 persons (750 households, 730 unique locations in 30 villages). ICCs were higher at household (0.20-0.69) than village levels (0.10-0.30) for all infection markers. Semivariograms identified significant spatial dependency for all markers (range 207-562 metres). Using Kulldorff's scan statistic, significant spatial clustering was observed in two previously known locations of ongoing transmission: for all markers in Fagali'i and all Abs in Vaitogi. Getis-Ord Gi* statistic identified hotspots of all markers in Fagali'i, Vaitogi, and Pago Pago-Anua areas. A hotspot of Ag and Wb123 Ab was identified around the villages of Nua-Seetaga-Asili. Bm14 and Bm33 Ab hotspots were seen in Maleimi and Vaitogi-Ili'ili-Tafuna.

CONCLUSION

Our study demonstrated the utility of different non-spatial and spatial methods for investigating clustering and hotspots, the benefits of using multiple infection markers, and the value of triangulating results between methods.

Infection-Derived Monocytic MDSCs Require TGF-β to Suppress Filarial-Specific IFN-γ But Not IL-13 Release by Filarial-Specific CD4+ T Cells In Vitro

Lymphatic filariasis (LF) remains a major health problem with severe economic repercussions in endemic communities of Sub-saharan Africa, South-East Asia and South America. The rodent-specific nematode Litomosoides sigmodontis (Ls) is used to study the immunomodulatory potential of filariae and research has elucidated pathways involving regulatory T cells (Tregs), IL-10 producing cells and alternatively activated macrophages (AAMs) and that CD4+ T cells play a paramount role during infection. Myeloid-derived suppressor cells (MDSCs) have been identified and characterised in man in cancer and other pathologies. The hallmark of MDSC populations is the suppression of T and B cell responses using various mechanisms, which are mostly specific to the pathology or setting. However, until now, it remains unclear whether they play a role in filarial-specific responses. We report here that monocytic MDSCs (Mo-MDSCs, CD11b+Ly6C+Ly6G-) and polymorphonuclear MDSCs (PMN-MDSCs, CD11b+Ly6Cint/loLy6G+) expanded in the thoracic cavity (TC, the site of infection) and correlated positively with filarial life-stages in Ls-infected BALB/c mice. In vitro, only infection-derived Mo-MDSCs showed a suppressive nature by preventing IL-13 and IFN-γ secretion from filarial-specific CD4+ T cells upon co-culture with soluble worm extract. This suppression was not mediated by IL-10, IL-6 or TNF-α, and did not require cell-contact, nitric oxide (NO), IL-4/IL-5 signalling pathways or CCR2. Interestingly, neutralizing TGF-β significantly rescued IFN-γ but not IL-13 production by filarial-specific CD4+ T cells. In comparison to naive cells, PCR array data showed an overall down-regulation of inflammatory pathways in both infection-derived Mo-MDSCs and PMN-MDSCs. In conclusion, these primary data sets show activity and expansion of MDSCs during Ls infection adding this regulatory cell type to the complex milieu of host responses during chronic helminth infections.

Filarial Lymphedema Patients Are Characterized by Exhausted CD4+ T Cells

Worldwide, more than 200 million people are infected with filariae which can cause severe symptoms leading to reduced quality of life and contribute to disability-adjusted life years (DALYs). In particular, lymphatic filariasis (LF) caused by Wuchereria bancrofti can lead to lymphedema (LE) and consequently presents a serious health problem. To understand why only a fraction of the infected individuals develop pathology, it is essential to understand how filariae regulate host immunity. The central role of T cells for immunity against filariae has been shown in several studies. However, there is little knowledge about T cell exhaustion, which causes T cell dysfunction and impaired immune responses, in this group of individuals. Recently, we showed that LE patients from Ghana harbor distinct patterns of exhausted effector and memory CD8⁺ T cell subsets. Based on these findings, we now characterized CD4⁺ T cell subsets from the same Ghanaian patient cohort by analyzing distinct markers within a 13-colour flow cytometry panel. We revealed that LE patients had increased frequencies of CD4⁺ T cells expressing exhaustion-associated receptors such as KLRG-1, TIM-3 and PD-1 compared to healthy endemic normal and W. bancrofti-infected individuals. Moreover, CD4⁺ T cells in LE patients were characterized by distinct co-expression patterns of inhibitory receptors. Collectively with the previous findings on CD8⁺ T cell exhaustion patterns, the data shown here demonstrates that filarial LE patients harbor distinct subsets of exhausted T cells. Thus, T cell exhaustion patterns in LE patients need attention especially in regards to susceptibility of concomitant infections and should be taken into consideration for LE management measures.

Effectiveness of community-based burden estimation to achieve elimination of lymphatic filariasis: A comparative cross-sectional investigation in Côte d'Ivoire

For lymphatic filariasis (LF) elimination, endemic countries must document the burden of LF morbidity (LFM). Community-based screening (CBS) is used to collect morbidity data, but evidence demonstrating its reliability is limited. Recent pilots of CBS for LFM alongside mass drug administration (MDA) in Côte d'Ivoire suggested low LFM prevalence (2.1-2.2 per 10,000). We estimated LFM prevalence in Bongouanou District, Côte d'Ivoire, using a comparative cross-sectional design. We compared CBS implemented independently of MDA, adapted from existing Ministry of Health protocols, to a population-based prevalence survey led by formally trained nurses. We evaluated the reliability of case identification, coverage, equity, and cost of CBS. CBS identified 87.4 cases of LFM per 10,000; the survey identified 47.5 (39.4-56.3; prevalence ratio [PR] 1.84; 95% CI 1.64-2.07). CBS identified 39.7 cases of suspect lymphoedema per 10,000; the survey confirmed 35.1 (29.2-41.5) filarial lymphoedema cases per 10,000 (PR 1.13 [0.98-1.31]). CBS identified 96.5 scrotal swellings per 10,000; the survey found 91.3 (83.2-99.8; PR 1.06 [0.93-1.21]); including 33.9 (27.7-38.8) filarial hydrocoele per 10,000 (PR of suspect to confirmed hydrocele 2.93 [2.46-3.55]). Positive predictive values for case identification through CBS were 65.0% (55.8-73.5%) for filarial lymphoedema; 93.7% (89.3-96.7%) for scrotal swellings; and 34.0% (27.3-41.2%) for filarial hydrocoele. Households of lower socioeconomic status and certain minority languages were at risk of exclusion. Direct financial costs were $0.17 per individual targeted and $69.62 per case confirmed. Our community-based approach to LFM burden estimation appears scalable and provided reliable prevalence estimates for LFM, scrotal swellings and LF-lymphoedema. The results represent a step-change improvement on CBS integrated with MDA, whilst remaining at programmatically feasible costs. Filarial hydrocoele cases were overestimated, attributable to the use of case definitions suitable for mass-screening by informal staff. Our findings are broadly applicable to countries aiming for LF elimination using CBS. The abstract is available in French in the S1 File.

Adoptive Transfer of Immune Cells Into RAG2IL-2Rγ-Deficient Mice During Litomosoides sigmodontis Infection: A Novel Approach to Investigate Filarial-Specific Immune Responses

Despite long-term mass drug administration programmes, approximately 220 million people are still infected with filariae in endemic regions. Several research studies have characterized host immune responses but a major obstacle for research on human filariae has been the inability to obtain adult worms which in turn has hindered analysis on infection kinetics and immune signalling. Although the Litomosoides sigmodontis filarial mouse model is well-established, the complex immunological mechanisms associated with filarial control and disease progression remain unclear and translation to human infections is difficult, especially since human filarial infections in rodents are limited. To overcome these obstacles, we performed adoptive immune cell transfer experiments into RAG2IL-2Rγ-deficient C57BL/6 mice. These mice lack T, B and natural killer cells and are susceptible to infection with the human filaria Loa loa. In this study, we revealed a long-term release of L. sigmodontis offspring (microfilariae) in RAG2IL-2Rγ-deficient C57BL/6 mice, which contrasts to C57BL/6 mice which normally eliminate the parasites before patency. We further showed that CD4⁺ T cells isolated from acute L. sigmodontis-infected C57BL/6 donor mice or mice that already cleared the infection were able to eliminate the parasite and prevent inflammation at the site of infection. In addition, the clearance of the parasites was associated with Th17 polarization of the CD4⁺ T cells. Consequently, adoptive transfer of immune cell subsets into RAG2IL-2Rγ-deficient C57BL/6 mice will provide an optimal platform to decipher characteristics of distinct immune cells that are crucial for the immunity against rodent and human filarial infections and moreover, might be useful for preclinical research, especially about the efficacy of macrofilaricidal drugs.

Human filariasis-contributions of the Litomosoides sigmodontis and Acanthocheilonema viteae animal model

Filariae are vector-borne parasitic nematodes that are endemic worldwide, in tropical and subtropical regions. Important human filariae spp. include Onchocerca volvulus, Wuchereria bancrofti and Brugia spp., and Loa loa and Mansonella spp. causing onchocerciasis (river blindness), lymphatic filariasis (lymphedema and hydrocele), loiasis (eye worm), and mansonelliasis, respectively. It is estimated that over 1 billion individuals live in endemic regions where filarial diseases are a public health concern contributing to significant disability adjusted life years (DALYs). Thus, efforts to control and eliminate filarial diseases were already launched by the WHO in the 1970s, especially against lymphatic filariasis and onchocerciasis, and are mainly based on mass drug administration (MDA) of microfilaricidal drugs (ivermectin, diethylcarbamazine, albendazole) to filarial endemic areas accompanied with vector control strategies with the goal to reduce the transmission. With the United Nations Sustainable Development Goals (SDGs), it was decided to eliminate transmission of onchocerciasis and stop lymphatic filariasis as a public health problem by 2030. It was also requested that novel drugs and treatment strategies be developed. Mouse models provide an important platform for anti-filarial drug research in a preclinical setting. This review presents an overview about the Litomosoides sigmodontis and Acanthocheilonema viteae filarial mouse models and their role in immunological research as well as preclinical studies about novel anti-filarial drugs and treatment strategies.

Diagnostics to support elimination of lymphatic filariasis-Development of two target product profiles

As lymphatic filariasis (LF) programs move closer to established targets for validation elimination of LF as a public health problem, diagnostic tools capable of supporting the needs of the programs are critical for success. Known limitations of existing diagnostic tools make it challenging to have confidence that program endpoints have been achieved. In 2019, the World Health Organization (WHO) established a Diagnostic Technical Advisory Group (DTAG) for Neglected Tropical Diseases tasked with prioritizing diagnostic needs including defining use-cases and target product profiles (TPPs) for needed tools. Subsequently, disease-specific DTAG subgroups, including one focused on LF, were established to develop TPPs and use-case analyses to be used by product developers. Here, we describe the development of two priority TPPs for LF diagnostics needed for making decisions for stopping mass drug administration (MDA) of a triple drug regimen and surveillance. Utilizing the WHO core TPP development process as the framework, the LF subgroup convened to discuss and determine attributes required for each use case. TPPs considered the following parameters: product use, design, performance, product configuration and cost, and access and equity. Version 1.0 TPPs for two use cases were published by WHO on 12 March 2021 within the WHO Global Observatory on Health Research and Development. A common TPP characteristic that emerged in both use cases was the need to identify new biomarkers that would allow for greater precision in program delivery. As LF diagnostic tests are rarely used for individual clinical diagnosis, it became apparent that reliance on population-based surveys for decision making requires consideration of test performance in the context of such surveys. In low prevalence settings, the number of false positive test results may lead to unnecessary continuation or resumption of MDA, thus wasting valuable resources and time. Therefore, highly specific diagnostic tools are paramount when used to measure low thresholds. The TPP process brought to the forefront the importance of linking use case, program platform and diagnostic performance characteristics when defining required criteria for diagnostic tools.

Control and elimination of lymphatic filariasis in Oceania: Prevalence, geographical distribution, mass drug administration, and surveillance in Samoa, 1998-2017

Lymphatic filariasis (LF) is a major public health problem globally and in the Pacific Region. The Global Programme to Eliminate LF has made great progress but LF is persistent and resurgent in some Pacific countries and territories. Samoa remains endemic for LF despite elimination efforts through multiple two-drug mass drug administrations (MDA) since 1965, including renewed elimination efforts started in 1999 under the Pacific Programme for Elimination of LF (PacELF). Despite eight rounds of national and two rounds of subnational MDA under PacELF, Samoa failed transmission assessment surveys (TAS) in all three evaluation units in 2017. In 2018, Samoa was the first to distribute countrywide triple-drug MDA using ivermectin, diethylcarbamazine (DEC), and albendazole. This paper provides a review of MDAs and historical survey results from 1998 to 2017 in Samoa and highlights lessons learnt from LF elimination efforts, including challenges and potential ways to overcome them to successfully achieve elimination.

Pharmacological characterization of novel heteromeric GluCl subtypes from C. elegans and parasitic nematodes

BACKGROUND AND PURPOSE

Macrocyclic lactones (MLs) are the most widely used broad-spectrum anthelmintic drugs for the treatment of parasitic nematodes impacting both human and animal health. MLs are known to act as agonist of the nematode glutamate-gated chloride channels (GluCls). However, for many important nematode species, the GluCls subunit composition and pharmacological properties remain largely unknown. In order to get new insights about the GluCl diversity and MLs mode of action, we identified and pharmacologically characterized receptors made of highly conserved GluCl subunits from the model nematode Caenorhabditis elegans, the human filarial nematode Brugia malayi and the horse parasite Parascaris univalens.

EXPERIMENTAL APPROACH

AVR-14, GLC-2, GLC3 and GLC-4 are the most conserved GluCl subunits throughout the Nematoda phylum. For each nematode species, we investigated the ability of these subunits to form either homomeric or heteromeric GluCls when expressed in Xenopus laevis oocytes and performed the detailed pharmacological characterization of the functional channels.

KEY RESULTS

Here, a total of 14 GluCls have been functionally reconstituted and heteromers formation was inferred from pharmacological criteria. Importantly, we report that the GLC-2 subunit plays a pivotal role in the composition of heteromeric GluCls in nematodes. In addition, we describe a novel GluCl subtype, made of the GLC-2/GLC-3 subunit combination, for which a high concentration of the anthelmintics ivermectin and moxidectin reversibly potentiate glutamate-induced response.

CONCLUSION AND IMPLICATIONS

This study brings new insights into the diversity of GluCl subtypes in nematodes and promote novel drug targets for the development of next generation anthelmintic compounds.

The implementation and impact of a pilot hydrocele surgery camp for LF-endemic communities in Ethiopia

BACKGROUND

Ethiopia aims to eliminate lymphatic filariasis by 2020, through a dual approach of mass drug administration to interrupt transmission and morbidity control which includes making hydrocele surgery available in all endemic areas. Locating patients requiring surgery, providing high quality surgeries, and following up patients are all formidable challenges for many resource-challenged or difficult-to-reach communities. To date, hydrocele surgery in Ethiopia has only occurred when a patient has the knowledge, time and resources to travel to regional hospitals. Ethiopia tested the novel approach of using a surgical camp, defined as mobilizing, transporting, providing surgery at a static site, and following up of a large cohort of hydrocele patients within a hospital's catchment area, to address delays in seeking and receiving care.

METHODOLOGY AND RESULTS

Health extension workers mobilized 252 patients with scrotal swelling from a list of 385 suspected hydrocele cases from seven endemic districts in the region of Beneshangul-Gumuz. Clinical health workers and surgeons confirmed 119 as eligible for surgery. Of 70 additional patients who self-referred, 56 were eligible for surgery. Over a two-week period at a regional hospital, 175 hydrocele excision surgeries were conducted. After discharge three days after surgery, trained clinical health workers followed up with the patients on Day 5, Day 8, Day 14 and 1st-month benchmarks with a randomized follow-up of a selection of patients conducted at 9-12 months. There were no post-operative complications upon discharge at Day 3 and 22, while minor complications occurred (12.6%) between Day 3 and one month. The 9-12 month follow-up found patients self-reported an improvement in quality of life, health and economic status.

CONCLUSION

A hydrocele surgery camp was effective at providing a large number of quality surgeries in a short time. Using peripheral health workers to mobilize and follow up patients helped address delays in seeking and receiving quality care. Mainstreaming patient mobilization and follow-up into a community health system could be effective in other countries. The camp's results also influenced two regions in Ethiopia to change their policies in order to offer free hydrocele surgery (including patient transport, consultation, surgery, diagnostic tests and necessary medications).

Recombinant antigens used as diagnostic tools for lymphatic filariasis

Lymphatic filariasis (LF) is a parasitic disease caused by the worms Wuchereria bancrofti, Brugia malayi, or Brugia timori. It is a tropical and subtropical illness that affects approximately 67 million people worldwide and that still requires better diagnostic tools to prevent its spread and enhance the effectiveness of control procedures. Traditional parasitological tests and diagnostic methods based on whole protein extracts from different worms are known for problems related to sample time collection, sensitivity, and specificity. More recently, new diagnostic tools based on immunological methods using recombinant antigens have been developed. The current review describes the several recombinant antigens used as tools for lymphatic filariasis diagnosis in antigen and antibody capture assays, highlighting their advantages and limitations as well as the main commercial tests developed based on them. The literature chronology is from 1991 to 2021. First, it describes the historical background related to the identification of relevant antigens and the generation of the recombinant polypeptides used for the LF diagnosis, also detailing features specific to each antigen. The subsequent section then discusses the use of those proteins to develop antigen and antibody capture tests to detect LF. So far, studies focusing on antibody capture assays are based on 13 different antigens with at least six commercially available tests, with five proteins further used for the development of antigen capture tests. Five antigens explored in this paper belong to the SXP/RAL-2 family (BmSXP, Bm14, WbSXP-1, Wb14, WbL), and the others are BmShp-1, Bm33, BmR1, BmVAH, WbVAH, BmALT-1, BmALT-2, and Wb123. It is expected that advances in research with these antigens will allow further development of tests combining both sensitivity and specificity with low costs, assisting the Global Program to Eliminate Lymphatic Filariasis (GPELF).

Distinct Immune Profiles of Exhausted Effector and Memory CD8+ T Cells in Individuals With Filarial Lymphedema

CD8⁺ T cells are crucial for the clearance of viral infections, and current research begins to highlight their importance in parasitic diseases too. In-depth research about characteristics of CD8⁺ T-cell subsets and exhaustion remains uncertain, especially during filariasis, a chronic helminth infection. Lymphatic filariasis, elicited by Wuchereria bancrofti, remains a serious health problem in endemic areas in Ghana, especially in those suffering from morbidity due to lymphedema (LE). In this observational study, the characteristics and profiles of CD8⁺ T cells were compared between asymptomatic Wuchereria bancrofti-infected individuals, uninfected endemic normals, and those with LE (grades 2–6). Focusing on exhausted memory (CD8⁺ex_mem: CD8⁺ T-bet^dimEomes^hi) and effector (CD8⁺ex_eff: CD8⁺T-bet^hiEomes^dim) CD8⁺ T-cell subsets, advanced flow cytometry revealed that LE individuals presented reduced frequencies of IFN-γ⁺CD8⁺ex_mem T cells expressing Tim-3 or LAG-3 which negatively correlated to the presence of LE. Moreover, the LE cohort further showed significantly higher frequencies of IL-10⁺CD8⁺ex_eff T cells expressing either Tim-3, LAG-3, CD39, KLRG-1, or PD-1, all associated markers of exhaustion, and that these frequencies positively correlated with the presence of LE. In summary, this study shows that distinct exhausted CD8⁺ T-cell subsets are prominent in individuals suffering from LE, suggesting that enhanced inflammation and constant immune activation might drive exhaustion of CD8⁺ T cells. Since T-cell exhaustion is known to be associated with insufficient control of persisting antigen, the data presented here reveals that these CD8⁺ T-cell exhaustion patterns in filarial LE should be taken into consideration for prevention and control management of LE.

Assessing factors influencing communities' acceptability of mass drug administration for the elimination of lymphatic filariasis in Guyana

BACKGROUND

Guyana is one of four countries in the Latin American Region where lymphatic filariasis (LF) remains endemic. In preparation for the introduction of a new triple drug therapy regimen (ivermectin, diethylcarbamazine, and albendazole (IDA)) in 2019, an acceptability study was embedded within sentinel site mapping in four regions to assess mass drug administration (MDA) coverage and compliance, acceptability, and perceptions about treatment and disease. The results from this survey would inform the rollout of IDA in Guyana in 2019.

METHODS

Data collection for the study occurred in August 2019, using a validated questionnaire administered by trained enumerators. Across all regions, a total of 1,248 participants were sampled by the Filarial Mapping team. Four-hundred and fifty-one participants aged over 18 years were randomly selected for participation in an expanded acceptability questionnaire. All data were captured in Secure Data Kit (SDK).

RESULTS

Acceptability was measured using a mean acceptability score. Unadjusted mean scores ranged from 24.6 to 29.3, with 22.5 as the threshold of acceptability. Regional variation occurred across many indicators of interest: self-rated understanding about LF, mechanisms of LF transmission, LF drug safety and history of treatment during MDA. Region IV (Georgetown) recorded higher knowledge about LF, but lower compliance and acceptability. Number of pills was not perceived as a concern.

CONCLUSION

Acceptability of MDA was good across all four regions under study. Results from this study set a baseline level for key indicators and acceptability, from which the acceptability of IDA can be measured. Regional variations across indicators suggest that localized approaches should be considered for social mobilization and MDA delivery to capture these contextual differences.

Anthelmintic resistance and homeostatic plasticity (Brugia malayi)

Homeostatic plasticity refers to the capacity of excitable cells to regulate their activity to make compensatory adjustments to long-lasting stimulation. It is found across the spectrum of vertebrate and invertebrate species and is driven by changes in cytosolic calcium; it has not been explored in parasitic nematodes when treated with therapeutic drugs. Here we have studied the adaptation of Brugia malayi to exposure to the anthelmintic, levamisole that activates muscle AChR ion-channels. We found three phases of the Brugia malayi motility responses as they adapted to levamisole: an initial spastic paralysis; a flaccid paralysis that follows; and finally, a recovery of motility with loss of sensitivity to levamisole at 4 h. Motility, calcium-imaging, patch-clamp and molecular experiments showed the muscle AChRs are dynamic with mechanisms that adjust their subtype composition and sensitivity to levamisole. This homeostatic plasticity allows the parasite to adapt resisting the anthelmintic.

The impact of podoconiosis, lymphatic filariasis, and leprosy on disability and mental well-being: A systematic review

Leprosy, podoconiosis, and lymphatic filariasis (LF) are among the priority neglected tropical diseases (NTDs) in Ethiopia. The disability, psychosocial, and mental health status of people affected by these NTDs are still overlooked in global NTD discourse. The objective of this systematic review was to synthesize the existing evidence describing the disability, psychosocial, and mental health status of people affected by leprosy, podoconiosis, and LF prior to developing a holistic physical and psychosocial care package for these individuals. We searched papers reporting on disability, psychosocial, and mental health status linked to these 3 NTDs. The protocol was registered in PROSPERO with registration number CRD42019128400. Peer-reviewed articles were searched and extracted from Medline, PsycINFO, Global Health, and Embase. Articles published in English, irrespective of the year of publication, using a quantitative study methodology, were included. Abstracts and full texts were reviewed by 2 reviewers. Data were extracted and narratively summarized, as the studies were heterogeneous and used different outcome measures. Out of 1,318 titles/abstracts screened and 59 full text studies reviewed, 24 fulfilled the inclusion criteria. Fourteen studies provided evidence of the disability associated with leprosy, podoconiosis, or LF. Ten studies provided evidence on the association between the 3 NTDs and mental health or psychosocial outcomes. The prevalence of grade 2 disability varied from 3.9% to 86%. The most commonly reported mental health impacts were depression and mental distress. A high burden of mental illness was reported, varying from 12.6% to 71.7%; the suicidal ideation was also high (18.5%). In conclusion, disability and poor psychosocial and mental health status are associated with leprosy, podoconiosis, and LF. For optimum management of these NTDs, holistic care including both physical and psychosocial interventions is vital.

Podoconiosis, lymphatic filariasis (LF), and leprosy are neglected tropical diseases (NTDs) that are commonly found among disadvantaged rural and some poor urban communities. These diseases lead to disabilities of the leg, which may result in reduced productivity. The longer the duration of the disease, the more severe the disability. People affected by these diseases also commonly experience stigma and discrimination, which, in turn, affect health-seeking behavior. Due to this disability, stigma, and discrimination, people affected by these 3 NTDs have a poor quality of life. We also found a range of mental health problems related to these 3 NTDs. Among these, the most common were mental distress and depression. As all 3 NTDs are associated with poor physical, psychosocial, and mental health outcomes, management should be holistic, incorporating physical, psychosocial, and mental health interventions. Following this review, we are working on the development of a holistic integrated care package for people affected by leprosy, podoconiosis, and LF in northwestern Ethiopia.

Disability, mental health, stigma and discrimination and neglected tropical diseases

The neglected tropical disease (NTD) agenda should include a focus on disability when ‘planning for the next decade of progress’. Millions of people are currently living with the disabling consequences of NTDs and mental health conditions are frequent among people living with NTDs. Stigma around NTDs is also common. However, these aspects of NTDs are often ignored by programmes that focus on infectious disease control. NTD programmes must broaden in scope to include provision of rehabilitation and linkages to mental health support and tackling stigma through demystifying NTDs. These efforts will promote the inclusion and well-being of people living with NTDs.

Zoonotic Vectorborne Pathogens and Ectoparasites of Dogs and Cats in Eastern and Southeast Asia

To provide data that can be used to inform treatment and prevention strategies for zoonotic pathogens in animal and human populations, we assessed the occurrence of zoonotic pathogens and their vectors on 2,381 client-owned dogs and cats living in metropolitan areas of 8 countries in eastern and Southeast Asia during 2017–2018. Overall exposure to ectoparasites was 42.4% in dogs and 31.3% in cats. Our data cover a wide geographic distribution of several pathogens, including Leishmania infantum and zoonotic species of filariae, and of animals infested with arthropods known to be vectors of zoonotic pathogens. Because dogs and cats share a common environment with humans, they are likely to be key reservoirs of pathogens that infect persons in the same environment. These results will help epidemiologists and policy makers provide tailored recommendations for future surveillance and prevention strategies.

Economic evaluations addressing diagnosis and treatment strategies for neglected tropical diseases: an overview

Neglected tropical diseases (NTDs) are those affecting vulnerable people and causing additional social and economic burden. The aim of this study was to carry out a general overview of the health economic assessments involving the diagnosis and treatment of six NTDs: cutaneous leishmaniasis (CL), Chagas disease, cysticercosis, filariasis, schistosomiasis and visceral leishmaniasis (VL). The literature search was based on two of the main medical literature databases (Medline and SciELO) and identified 46 studies. Twenty-six studies (57%) addressed therapeutic strategies, while other 20 (43%) assessed diagnostic or both diagnostic and therapeutic approaches. The studies were published between 1994 and 2021, and 57% of them (26/46) were carried out in four countries. Cost-effectiveness analyses were conducted in 59% (27/46) of the studies. Economic studies of NTDs have timidly increased in recent years. Despite the improvement of analytical methods, completeness and accuracy of information, there are few new technologies applied to NTDs and public health systems. In addition, economic studies for NTDs are concentrated in a few countries. Thus, this review points out the need for investment in research, development and training of human resources dedicated to the economic analysis in health, especially on NTDs, as a strategy to reduce inequalities by optimizing the use of health resources.

Progress and impact of 20 years of a lymphatic filariasis elimination programme in South-East Asia

Background

The South-East Asia regional programme to eliminate lymphatic filariasis (LF) was launched in 2000. This study presents the progress and impact of the programme in the region.

Methods

Mass drug administration (MDA) and morbidity management data were accessed from the WHO preventive chemotherapy databank. The status of the programme in the nine South-East Asia countries was reviewed and progress was assessed. The impact of the programme on LF disease burden was estimated on the basis of the effectiveness of the MDA drugs against microfilaraemia and chronic disease.

Results

Under the MDA programme, 8.1 billion treatments were delivered in nine countries and 5.7 billion treatments were consumed by the target population during 2001–2018. Three of nine countries eliminated LF. Bangladesh is poised to reach its elimination goal by 2021. In the other five countries, 38–76% of intervention units completed intervention and surveillance is in progress. The MDA programme prevented or cured 74.9 million infections, equivalent to an 84.2% reduction. Close to 1 million lymphoedema patients and 0.5 million hydrocele patients were reported and are being provided with the minimum package of care.

Conclusions

The South-East Asia region's LF elimination programme reduced the burden of LF appreciably and is moving towards achieving the elimination goal in the next 8–10 y.

Caring for patients in the global programme to eliminate lymphatic filariasis

Clinical lymphatic filariasis (LF) is a debilitating, disfiguring medical condition with severe psychosocial consequences for patients and their families. Addressing these patients’ medical needs is a major component of the global programme to eliminate lymphatic filariasis (GPELF). In the 20 y of providing a minimal package of care many thousands of surgical operations to correct LF hydrocoeles been performed and national programmes in >90% of LF endemic countries have received the training needed to care for their patients. The creation of educational materials detailing appropriate patient care, together with increased funding, have been key catalysts in increasing awareness of clinical LF in recent years. Nevertheless, the implementation of care for these patients has often faced challenges that have led to delays in fully implementing the patient care component of GPELF; these include locating these often stigmatised individuals, maintaining provision of the necessary consumables (e.g. soaps and creams) and maintaining programme support within already overstretched national LF teams. As the LF global programme moves to achieve success by 2030 it will be vital to continue to focus efforts on the care and rehabilitation of those suffering from lymphoedema and hydrocoeles, learning from the experiences of the past 20 y.

Triple-Drug Treatment Is Effective for Lymphatic Filariasis Microfilaria Clearance in Samoa

Following the first triple-drug mass drug administration (MDA) for lymphatic filariasis in Samoa in 2018, unexpected persistence of microfilaria (Mf) positivity in 18 (15%) of 121 antigen-positive persons was observed in a nationwide household survey 1–2 months later. Of the 18 Mf positive persons, 14 reported taking the MDA, raising concerns about MDA efficacy. In 2019, 5–6 months after the 2018 survey, a monitored treatment study was done to evaluate directly observed weight-based treatment in these Mf positive individuals. Mf presence and density were assessed before and 7 days after treatment, using 1 mL membrane filtered venous blood, and 60 uL thick blood films on slides prepared from venous or fingerprick blood. All 14 participants were still Mf positive on filters from venous blood pre-treatment samples, but two were negative by slide made from the same samples. Mf were cleared completely by day 7 in 12 of 13 participants followed up, and by day 30 in the remaining participant. Filtered blood using EDTA samples (to reduce clumping of Mf) is preferred over slides alone for improving the likelihood of detecting Mf and estimating their density. The triple-drug MDA strategy was effective at clearing Mf when given and taken at the correct dose.

Larvicidal Activity of Elytraria acaulis against Culex quinquefasciatus and Aedes aegypti (Diptera: Culicidae)

Background

Mosquitoes are blood sucking arthropods and serve as vectors of many diseases causing serious health problems to human beings. Culex quinquefasciatus and Aedes aegypti were responsible for Filariasis and Dengue. Synthetic pesticides were effective against mosquitoes as well as main sources of environmental pollution and most of them are immunosuppressant. Botanicals were widely used as insecticides, growth disruptors, repellents, etc. The aim of this research was to determine larvicidal properties of powdered leaf, Elytraria acaulis against late third or early fourth in-star larvae of Cx. quinquefasciatus and Ae. aegypti.

Methods

Larvae of Cx. quinquefasciatus and Ae. aegypti were tested at various concentrations of 100, 120, 140, 160, 180 and 200mg/100ml and mortality was recorded after 24h. The LC₅₀ values of the E. acaulis leaf powder were calculated by Probit analysis.

Results

The plant powder exhibited strong larvicidal activity against Cx. quinquefasciatus with LC₅₀ value of 116.07mg/100ml against Ae. aegypti 124.25mg/100ml respectively. The result indicated that the plant powder of E. acaulis showed potential larvicidal activity against Cx. quinquefasciatus and Ae. aegypti.

Conclusion

The overall findings of the present investigation suggested that the E. acaulis highly effective against Cx. quinquefasciatus and Ae. aegypti larvae. Elytraria acaulis may be used as an alternative to synthetic chemical pesticides for control of vectors to reduce vector borne diseases and did not harm to total environment.

Monitoring migrant groups as a post-validation surveillance approach to contain the potential reemergence of lymphatic filariasis in Togo

BACKGROUND

In March 2017, Togo was declared the first country in sub-Saharan Africa to eliminate lymphatic filariasis as a public health problem, but post-validation surveillance has been lacking. In some areas of the country, migrant groups from neighboring countries that are still endemic for LF pose a risk of reintroduction of LF to Togo. The objective of this study was to identify the risk posed by migrant groups by measuring their prevalence of LF infection and investigating any positive case using Togo's case investigation algorithm to prevent resurgence of LF and sustain Togo's elimination success.

METHOD

A cross-sectional study was conducted in 2018 in the northernmost region of the country. Three migrant populations were identified: (i) nomadic Peuhls, (ii) Togolese members of local communities who migrate annually to neighboring countries for seasonal labor, and (iii) refugees from Ghana who came to Togo because of a communal conflict in Ghana. A questionnaire was designed to collect data on demographics and history of LF and MDA; all participants were tested for circulating filariasis antigen (CFA) using the filariasis test strip (FTS). Any CFA-positive case was confirmed with nocturnal microfilaremia.

RESULTS

Refugees, seasonal economic migrants and nomadic Peuhls represented 42.1%, 31.4% and 26.5% of the study participants, respectively. The overall prevalence of CFA was 4.2% (58/1391) with the highest prevalence in the nomadic Peuhl group (11.9%), but only one of them (0.07%) was confirmed positive with nocturnal microfilaremia. Using the case investigation algorithm, no other positive case was identified in the positive case's surroundings.

CONCLUSION

This study demonstrates that nomadic Peuhls, with a CFA prevalence of 11.9%, pose a potential risk for reintroduction of LF into Togo while Ghanaian refugees and seasonal economic migrants do not appear to pose a significant risk. Periodic monitoring of migrants, especially the nomadic Peuhl population, is a potential post-validation surveillance approach that could be used to promptly detect any LF cluster that may arise.

Tetracyclines improve experimental lymphatic filariasis pathology by disrupting interleukin-4 receptor-mediated lymphangiogenesis

Lymphatic filariasis is the major global cause of nonhereditary lymphedema. We demonstrate that the filarial nematode Brugia malayi induced lymphatic remodeling and impaired lymphatic drainage following parasitism of limb lymphatics in a mouse model. Lymphatic insufficiency was associated with elevated circulating lymphangiogenic mediators, including vascular endothelial growth factor C. Lymphatic insufficiency was dependent on type 2 adaptive immunity, the interleukin-4 receptor, and recruitment of C-C chemokine receptor-2–positive monocytes and alternatively activated macrophages with a prolymphangiogenic phenotype. Oral treatments with second-generation tetracyclines improved lymphatic function, while other classes of antibiotic had no significant effect. Second-generation tetracyclines directly targeted lymphatic endothelial cell proliferation and modified type 2 prolymphangiogenic macrophage development. Doxycycline treatment impeded monocyte recruitment, inhibited polarization of alternatively activated macrophages, and suppressed T cell adaptive immune responses following infection. Our results determine a mechanism of action for the antimorbidity effects of doxycycline in filariasis and support clinical evaluation of second-generation tetracyclines as affordable, safe therapeutics for lymphedemas of chronic inflammatory origin.

Comparative Assessment of the Pharmacovigilance Systems within the Neglected Tropical Diseases Programs in East Africa-Ethiopia, Kenya, Rwanda, and Tanzania

Monitoring the safety of medicines used in public health programs (PHPs), including the neglected tropical diseases (NTD) program, is a WHO recommendation, and requires a well-established and robust pharmacovigilance system. The objective of this study was to assess the pharmacovigilance systems within the NTD programs in Ethiopia, Kenya, Rwanda, and Tanzania. The East African Community Harmonized Pharmacovigilance Indicators tool for PHPs was used to interview the staff of the national NTD programs. Data on four components, (i) systems, structures, and stakeholder coordination; (ii) data management and signal generation; (iii) risk assessment and evaluation; and (iv) risk management and communication, were collected and analyzed. The NTD programs in the four countries had a strategic master plan, with pharmacovigilance components and mechanisms to disseminate pharmacovigilance information. However, zero individual case safety reports were received in the last 12 months (2017/2018). There was either limited or no collaboration between the NTD programs and their respective national pharmacovigilance centers. None of the NTD programs had a specific budget for pharmacovigilance. The NTD program in all four countries had some safety monitoring elements. However, key elements, such as the reporting of adverse events, collaboration with national pharmacovigilance centers, and budget for pharmacovigilance activity, were limited/missing.