A retrospective analysis on the transmission of Plasmodium falciparum and Plasmodium vivax: the case of Adama City, East Shoa Zone, Oromia, Ethiopia

Seasonal Dynamics of Symptomatic and Asymptomatic Plasmodium falciparum and Plasmodium vivax Infections in Coendemic Low-Transmission Settings, South Ethiopia

Ethiopia has a plan to eliminate malaria in selected low-transmission districts by 2025. However, complex factors such as seasonality, focal heterogeneity, and coendemicity of Plasmodium vivax and Plasmodium falciparum, and asymptomatic cases, along with other factors, pose challenges. This longitudinal study assessed these dynamics and associated factors in three elimination-targeted settings in southern Ethiopia. The study included rural districts (Wonago and Yirgacheffe) and an urban setting (Dilla town) with 504 participants from 168 households per season. The study covered the peak and minor malaria transmission seasons and the dry season. Finger-prick blood was collected for microscopy, rapid diagnostic tests, and 18S-rRNA-based quantitative polymerase chain reaction (qPCR). During the dry season, P. vivax accounted for most infections (64.5%, 71/110) and symptomatic malaria (50.9%, 29/57), whereas P. falciparum dominated during the peak transmission season (45.7%, 42/92 infections and 58.1%, 25/43 of symptomatic cases). Treatment-seeking behavior was low, with 65.3% (143/219) of symptomatic individuals not seeking treatment. Dilla town had significantly higher infection prevalence (29.6%, 149/504, P <0.001) in all seasons compared with the rural sites. The incidence rate was 12/1,000 person-seasons by qPCR and 5/1,000 person-seasons by microscopy. Urban residents, those with low hemoglobin levels, nonuse of mosquito nets, and proximity to stagnant water had a significantly higher risk of infection (P <0.001). Tailored approaches are needed in elimination-targeted areas, focusing on urban settings, Plasmodium species, and strengthening community-level interventions for behavioral change and active case detection.

Malaria positivity rate trend analysis at water resources development project of Wonji Sugar Estate Oromia, Ethiopia

Evidence on the trends of the proportion of malaria infections detected by routine passive case detection at health facilities is important for public health decision making especially in areas moving towards elimination. The objective was to assess nine years of trends on clinical malaria infections detected at health facility and its associated climate factors, in the water resource development set up of Wonji sugar estate, Oromia, Ethiopia. Retrospective data were collected from malaria-suspected patient recording logbook at Wonji sugar factory's primary hospital. Monthly average meteorological data were obtained from the estate meteorological station. Data were collected from April through June 2018 and January 2022. The data were analyzed using Stata version 16.0 software for Chi-square and regression analysis. Over the last nine years, 34,388 cases were legible for analysis with complete data. Of these, 11.75% (4039/34388) were positive for clinical malaria. Plasmodium vivax test positivity was the highest proportion (8.2%, n = 2820) followed by Plasmodium falciparum (3.48%, n = 1197) and mixed infections (P. falciparum and P. vivax, 0.06%, n = 21). The odds of being positive for malaria was highest in males (AOR = 1.46; 95%CI = 1.36-1.52; P < 0.001) compared to females and in older individuals of above 15 years old (AOR = 4.55, 95%CI = 4.01-5.17, P < 0.001) followed by school-aged children (5-15 years old) (AOR = 2.16; 95%CI = 1.88-2.49, P < 0.001). There was no significant variation in the proportion of malaria-positive cases in the dry and wet seasons (P = 0.059). Malaria test positivity rates were associated with average monthly rainfall (AdjIRR = 1.00; 95%CI = 1.00-1.001, P < 0.001) while negatively associated with average monthly minim temperature (adjIRR = 0.94; 95%CI = 0.94-0.95; P < 0.001) and average monthly relative humidity (adjIRR = 0.99, 95%CI = 0.99-1.00, P = 0.023). There was year-round malaria transmission, adults especially males and school children frequently tested malaria positive. Hence, alternative vector management tools like larval source management have to be deployed besides ITNs and IRS in such water development areas to achieve the malaria elimination goal.

A Five-Year (2016-2020) Trend Analysis of Malaria Surveillance Data in Oromia Regional State, Ethiopia

Background

Continuous malaria surveillance data analysis plays a significant role in monitoring trends over time and evaluating the effectiveness of malaria prevention and control programs. Hence, this study was part of an effort to achieve this goal. This study's main aim was to analyse five years (2016-2020) of malaria surveillance data in the Oromia Region, Ethiopia.

Methods

A descriptive cross-sectional study design was used to analyse the five-year (2016-2020) trend of malaria cases in the Oromia Regional State, Ethiopia.

Results

A total of 5,843,373malaria suspected cases were reported during the five-year period. Among the total reported cases, 727,738 were a total of both clinical and parasitological confirmed cases. The average total malaria annual parasite incidence (API) was 4 per 1,000 persons. The highest malaria cases were observed during the spring and summer seasons. Conclusions and Recommendation. Trends of total clinical and confirmed malaria cases decreased from year to year except for the recent year with an exceptional variability in 2019. The highest or peak of malaria cases was observed during spring season (September-November). Malaria indicator-based performance plans and achievements should be regularly and strictly reviewed and evaluated at each level.

Therapeutic efficacy of Chloroquine for the treatment of uncomplicated Plasmodium vivax infection in Shewa Robit, Northeast Ethiopia

BACKGROUND

The development of drug resistance to chloroquine is posing a challenge in the prevention and control efforts of malaria globally. Chloroquine is the first-line treatment for uncomplicated P.vivax in Ethiopia. Regular monitoring of anti-malarial drugs is recommended to help early detection of drug-resistant strains of malaria parasites before widely distributed. The emergence of P.vivax resistance to chloroquine in the country endangers the efficacy of P.vivax treatment. This study aimed to assess the therapeutic efficacy of chloroquine among uncomplicated P.vivax infections at Shewa Robit Health Center, northeast Ethiopia.

METHODS

One-arm in vivo prospective chloroquine efficacy study was conducted from November 2020 to March 2021. Ninety participants aged between 16 months to 60 years confirmed with P.vivax mono-infection microscopically were selected and treated with a 25 mg/kg standard dose of chloroquine over three days. Thick and thin blood smears were prepared and examined. Clinical examination was performed over 28 follow-up days. Hemoglobin concentration level was measured on days 0, 14, and 28.

RESULT

Of the 90 enrolled participants, 86 (96%) completed their 28 days follow-up period. The overall cure rate of the drug was 98.8% (95% CI: 95.3-100%). All asexual stages and gametocytes were cleared within 48 hours with rapid clearance of fever. Hemoglobin concentration had significantly recovered between days 0 and 14, 0 and 28, and 14 and 28 days (P = 0.032, P<0.001, and P = 0.005), respectively. Fast resolution of clinical signs and symptoms was also observed. Severe adverse events were not recorded.

CONCLUSION

The present study revealed that chloroquine remains an efficacious and safe drug in the study setting for treating uncomplicated P.vivax in the study area. Large-scale continuous surveillance is needed to monitor the development of resistance in due time.

Plasmodium vivax: the potential obstacles it presents to malaria elimination and eradication

Initiatives to eradicate malaria have a good impact on P. falciparum malaria worldwide. P. vivax, however, still presents significant difficulties. This is due to its unique biological traits, which, in comparison to P. falciparum, pose serious challenges for malaria elimination approaches. P. vivax's numerous distinctive characteristics and its ability to live for weeks to years in liver cells in its hypnozoite form, which may elude the human immune system and blood-stage therapy and offer protection during mosquito-free seasons. Many malaria patients are not fully treated because of contraindications to primaquine use in pregnant and nursing women and are still vulnerable to P. vivax relapses, although there are medications that could radical cure P. vivax. Additionally, due to CYP2D6's highly variable genetic polymorphism, the pharmacokinetics of primaquine may be impacted. Due to their inability to metabolize PQ, some CYP2D6 polymorphism alleles can cause patients to not respond to treatment. Tafenoquine offers a radical treatment in a single dose that overcomes the potentially serious problem of poor adherence to daily primaquine. Despite this benefit, hemolysis of the early erythrocytes continues in individuals with G6PD deficiency until all susceptible cells have been eliminated. Field techniques such as microscopy or rapid diagnostic tests (RDTs) miss the large number of submicroscopic and/or asymptomatic infections brought on by reticulocyte tropism and the low parasitemia levels that accompany it. Moreover, P. vivax gametocytes grow more quickly and are much more prevalent in the bloodstream. P. vivax populations also have a great deal of genetic variation throughout their genome, which ensures evolutionary fitness and boosts adaptation potential. Furthermore, P. vivax fully develops in the mosquito faster than P. falciparum. These characteristics contribute to parasite reservoirs in the human population and facilitate faster transmission. Overall, no genuine chance of eradication is predicted in the next few years unless new tools for lowering malaria transmission are developed (i.e., malaria elimination and eradication). The challenging characteristics of P. vivax that impede the elimination and eradication of malaria are thus discussed in this article.

Assessment of malaria prevalence in Boset District, East Shawa Zone, Oromia Regional State, Ethiopia: a retrospective study

Objective

In this study, we aimed to assess the epidemiological profile and associated risk factors of malaria in Boset District using clinical records from the Boset District Health Office Central Surveillance Unit, East Shawa Zone, Oromia, Ethiopia.

Methods

This health facility-based retrospective cross-sectional study included clinical malaria data for 5 years (2016–2020) recorded at all public and private health facilities in the district.

Results

The present study revealed an overall malaria slide positivity rate of 12.4% (21,059/169,986), ranging from 23.3% to 5.3% during 2016–2020 in Boset District. Malaria cases were recorded in all age groups, but individuals aged 15 years and above accounted for a higher (56.2%) average proportion of malaria cases. Concerning the relative proportion of malaria parasite species, Plasmodium falciparum was slightly predominant (58%) over P. vivax (42%).

Conclusion

The present study revealed a declining trend in malaria cases over the 5-year study period in Boset District. Scaling up the available malaria prevention strategies and control measures is recommended to achieve malaria pre-elimination.

Assessing the diagnostic performance of a novel RT-PCR fluorescence method for the detection of human plasmodium species

Background

Malaria elimination effort is hampered not only by the lack of effective medication but also due to the lack of sensitive diagnostic tools to detect infections with low levels of parasitemia. Therefore, more sensitive and specific high-throughput molecular diagnostic approaches are needed for accurate malaria diagnosis.

Methods

In the present study, the performance of a novel single-tube MC004 real-time polymerase chain reaction (PCR) assay (MRC-Holland, Amsterdam, the Netherlands) was assessed for the detection of infection and discrimination of Plasmodium species. Blood samples (n = 150) were collected from malaria suspected patients at Adama malaria diagnosis and treatment centre, Adama, central Ethiopia. The positive predictive value (PPV), negative predictive value (NPV), analytical sensitivity and specificity of the assay were assessed against the conventional microscopic method.

Results

Plasmodium species were detected in 59 (39.3%) of the samples by microscopy and in 62 (41.3%) by the novel MC004 RT-PCR. Plasmodium vivax, Plasmodium falciparum and mixed infections with Plasmodium falciparum & Plasmodium vivax accounted for 47.5%, 40.6% and 11.9% respectively as detected by microscopy. The MC004 RT-PCR assay identified 59.7% and 40.3% of the samples positive for Plasmodium vivax and Plasmodium falciparum respectively. The sensitivity, specificity, PPV, and NPV of the MC004 RT-PCR assay were 95.8%, 97.8%, 92%, and 98.9%, respectively. No mixed infections were detected using the MC004 assay.

Conclusion

The MC004 RT-PCR assay is a useful tool for the early detection of malaria and identification of Plasmodium species with a high degree of sensitivity and specificity. Due to its high sensitivity, and simplicity (being a single-tube assay), the MC004 is suitable for use in clinical settings and epidemiological studies.

Plasmodium falciparum Clinical Isolates Reveal Analogous Circulation of 3D7 and FC27 Allelic Variants and Multiplicity of Infection in Urban and Rural Settings: The Case of Adama and Its Surroundings, Oromia, Ethiopia

Background

Despite significant progress achieved globally in reducing malaria burden, still it is one of the major public health and economic problems in Ethiopia. Investigation of the local genetic polymorphism of P. falciparum, the most virulent and predominant malaria parasite primarily targeted in malaria control and elimination program, is paramount to assess intensity of parasite transmission. Analysis of the block 3 region of the msp-2 gene of P. falciparum provides strong molecular evidence to evaluate the real picture of malaria epidemiology to fine-tune the ongoing control and elimination programs in the region. Thus, this study was aimed at examining the status of such polymorphic gene and its implications in Adama and its surroundings.

Methods

148 isolates from patients with uncomplicated falciparum malaria were collected in the study from September 2019 to August 2020. Tween® 20 and the Chelex method were employed for parasite DNA extraction. msp-2 allelic families were genotyped by using nested polymerase chain reaction targeting its 3D7 and FC27 allelic variants followed by gel electrophoresis for fragment analysis.

Results

Seventeen different polymorphic forms of msp-2 allelic fragments were detected in the study area. Moreover, 47 (31.8%) and 41(27.7%) were detected for 3D7 and FC27 allelic families, respectively. Furthermore, the multiclonal allele type accounted for 60 (40.5%). The mean MOI was 1.4, and the heterogeneity index (He) is 0.49 indicating nearly intermediate malaria transmission in the study area.

Conclusions

The study revealed nearly intermediate genetic diversity and mean MOI of P. falciparum in the study area, demanding further scale up of the ongoing control and elimination efforts.

Six-year trend analysis of malaria prevalence at University of Gondar Specialized Referral Hospital, Northwest Ethiopia, from 2014 to 2019

Globally, malaria is the major public health disease caused by plasmodium species and transmitted by the bite of the female anopheles mosquito. Assessment of the trend of malaria prevalence is important in the control and prevention of the disease. Therefore, the objective of this study was to assess the six year trend of malaria prevalence at the University of Gondar Comprehensive Specialized Hospital, northwest Ethiopia, from 2014 to 2019. A retrospective laboratory registration logbook review study was conducted on the malaria blood film examination results at the University of Gondar Comprehensive Specialized Hospital. The data was collected by using a data extraction tool and entered into SPSS version 20 for analysis. Descriptive statistics were used to summarize the socio-demographic characteristics of study participants and presented by graphs, tables and texts. The binary logistic regression was also used to test the association the trend of malaria prevalence and different factors like sex, age, year, and season. From a total of 17,500 malaria blood film examinations, 1341 (7.7%) were confirmed for malaria parasites. Of the confirmed malaria cases, 47.2%, 45.6% and 7.2% were P. vivax, P. falciparum and mixed infection, respectively. The proportion of P. vivax was the predominant species in the first three study years (2014-2016) and P. falciparum became the predominant species in the last three study years (2017-2019). The odds of malaria prevalence was lower by 68%, 60% and 69% in the year 2017, 2018 and 2019 compared to 2014, respectively. It was also 1.41 times higher in males than in females. Moreover, the odds of malaria prevalence were 1.60, 1.64, 2.45 and 1.82 times higher in the age group of < 5, 5-14, 15-24 and 25-54 years old compared to the older age groups (> 54 years old), respectively. Even there was a significant declining in prevalence trend; malaria is still a major public health problem. The study showed that there was high seasonal fluctuation from year to year. Moreover, males and the younger age groups were more affected than females and old age groups, respectively. Therefore, malaria prevention and control activities should be strengthened and require extra efforts by considering these variability.

In vivo efficacy of anti-malarial drugs against clinical Plasmodium vivax malaria in Ethiopia: a systematic review and meta-analysis

Background

Ethiopia is one of the few countries in Africa where Plasmodium vivax commonly co-exists with Plasmodium falciparum, and which accounts for ~ 40% of the total number of malaria infections in the country. Regardless of the growing evidence over many decades of decreasing sensitivity of this parasite to different anti-malarial drugs, there has been no comprehensive attempt made to systematically review and meta-analyse the efficacy of different anti-malarial drugs against P. vivax in the country. However, outlining the efficacy of available anti-malarial drugs against this parasite is essential to guide recommendations for the optimal therapeutic strategy to use in clinical practice. The aim of this study was to synthesize evidence on the efficacy of anti-malarial drugs against clinical P. vivax malaria in Ethiopia.

Methods

All potentially relevant, peer-reviewed articles accessible in PubMed, Scopus, Web of Science, and Clinical Trial.gov electronic databases were retrieved using a search strategy combining keywords and related database-specific subject terms. Randomized controlled trials (RCTs) and non-randomized trials aiming to investigate the efficacy of anti-malarial drugs against P. vivax were included in the review. Data were analysed using Review Manager Software. Cochrane Q (χ²) and the I² tests were used to assess heterogeneity. The funnel plot and Egger’s test were used to examine risk of publication bias.

Results

Out of 1294 identified citations, 14 articles that presented data on 29 treatment options were included in the analysis. These studies enrolled 2144 clinical vivax malaria patients. The pooled estimate of in vivo efficacy of anti-malarial drugs against vivax malaria in Ethiopia was 97.91% (95% CI: 97.29–98.52%), with significant heterogeneity (I² = 86%, p < 0.0001) and publication bias (Egger’s test = -12.86, p < 0.001). Different anti-malarial drugs showed varied efficacies against vivax malaria. The duration of follow-up significantly affected the calculated efficacy of any given anti-malarial drug, with longer duration of the follow-up (42 days) associated with significantly lower efficacy than efficacy reported on day 28. Also, pooled PCR-corrected efficacy and efficacy estimated from altitudinally lower transmission settings were significantly higher than PCR-uncorrected efficacy that estimated for moderate transmission settings, respectively.

Conclusion

The overall efficacy of anti-malarial drugs evaluated for the treatment of vivax malaria in Ethiopia was generally high, although there was wide-ranging degree of efficacy, which was affected by the treatment options, duration of follow-up, transmission intensity, and the confirmation procedures for recurrent parasitaemia. Regardless of evidence of sporadic efficacy reduction reported in the country, chloroquine (CQ), the first-line regimen in Ethiopia, remained highly efficacious, supporting its continuous utilization for confirmed P. vivax mono-infections. The addition of primaquine (PQ) to CQ is recommended, as this is the only approved way to provide radical cure, and thus ensure sustained efficacy and longer protection against P. vivax. Continuous surveillance of the efficacy of anti-malarial drugs and clinical trials to allow robust conclusions remains necessary to proactively act against possible emergence and spread of drug-resistant P. vivax in Ethiopia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-04016-2.

Five-Year Trend Analysis of Malaria Cases in East Shawa Zone, Ethiopia

BACKGROUND

Malaria is an infectious disease caused by Plasmodium parasites. Of the five human malaria parasites Plasmodium falciparum and Plasmodium vivax are the two co-endemic predominant and widely distributed species in Ethiopia, with major public health importance. Even though enormous effort has been made countrywide to reduce the disease burden little was reported about trends of malaria transmission in the several localities of malarious areas like East Shawa Zone, Ethiopia. Thus, the present study was aimed at assessing fiveyear (2016-2020) trends of malaria transmission at Adama, Boset and Lume districts of East Shawa Zone of Oromia Regional State, Ethiopia.

METHODS

Retrospective data was extracted from the central surveillance database of East Shawa Zone Health Office. The data collected was analyzed from September 2020 to December 2020 to examine trends of malaria epidemiology in three malarious districts in the Zone.

RESULTS

The results of the present study showed a remarkable decrease in slide positivity rate (SPR) from 16.3 to 1.4% from 2016 to 2018 in the areas. However, a recent slight increase of malaria SPR was observed. On the other hand, as age increases more male individuals were infected with malaria compared to female of similar age groups. Falciparum, vivax and mixed malaria infection accounted for 53%, 41% and 6% respectively.

CONCLUSIONS

Even though, an overall reduction of malaria incidence was revealed in the study areas, an increase in malaria SPR was observed in 2019 and 2020. Such inconsistency in reduction of malaria cases in the study area demands due attention of health planners.

Detection of high frequency of MAD20 allelic variants of Plasmodium falciparum merozoite surface protein 1 gene from Adama and its surroundings, Oromia, Ethiopia

Background

One of the major challenges in developing an effective vaccine against asexual stages of Plasmodium falciparum is genetic polymorphism within parasite population. Understanding the genetic polymorphism like block 2 region of merozoite surface protein-1 (msp-1) gene of P. falciparum enlighten mechanisms underlining disease pathology, identification of the parasite clone profile from the isolates, transmission intensity and potential deficiencies of the ongoing malaria control and elimination efforts in the locality. Detailed understanding of local genetic polymorphism is an input to pave the way for better management, control and elimination of malaria. The aim of this study was to detect the most frequent allelic variant of the msp-1 gene of P. falciparum clinical isolates from selected health facilities in Adama town and its surroundings, Oromia, Ethiopia.

Methods

One hundred thirty-nine clinical isolates were successfully amplified for msp-1 gene using specific primers. Nested PCR amplification was conducted targeting K1, MAD20, and R033 alleles followed by gel electrophoresis for fragment analysis. Based on the detection of a PCR fragment, infections were classified as monoclonal or multiple infections.

Results

19 different size polymorphism of msp-1 gene were identified in the study, with 67(48%) MAD20, 18 (13%) K-1 and 18 (13%) RO33 allelic family. Whereas, the multiple infections were 21(15%), 8 (5.8%), 4(2.9%), 3(2.2%) for MAD20 + K-1, MAD20 + RO33, K-1 + RO33, and MAD20 + K-1, RO33, respectively. The overall Multiplicity of infection (MOI) was 1.3 and the expected heterozygosity (He) was 0.39 indicating slightly low falciparum malaria transmission.

Conclusion

The status of msp-1 allele size polymorphism, MOI and He observed in the study revealed the presence of slightly low genetic diversity of P. falciparum clinical isolates. However, highly frequent MAD20 allelic variant was detected from clinical isolates in the study area. Moreover, the driving force that led to high predominance of MAD20 allelic variant revealed in such malaria declining region demands further research.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03914-9.

A preliminary study on urban malaria during the minor transmission season: The case of Adama City, Oromia, Ethiopia

The distribution of malaria shows considerable spatial heterogeneity globally, regionally and locally. For the design of effective malaria control and elimination, and for its implementation in Ethiopia, urban malaria should be given due attention. Therefore, the present study was aimed to examine the status of urban malaria during the minor transmission season in Adama city. A total of 2590 febrile patients were screened using the gold standard microscopy-based blood test for malaria diagnosis from seven purposively selected health facilities found in Adama City from April to July 2018. Socio-demographic data were collected from malaria positive patients to correlate predisposing factors; like previous malaria history, settlement, travel history, age, and other associated risk factors with malaria incidence. Climatological data, such as temperature and relative humidity, recorded during the study period were also collected from the data base of Adama meteorology center for analysis. The microscopic data indicated that from a total of 2590 febrile patients screened for malaria during the study period 3.7% (97/2590) of them were confirmed malaria positive. Adolescents and adults (≥15 years of age) were found to be most affected by Plasmodium vivax (66%) and Plasmodium falciparum (20.5%), and mixed (6%). Analysis of the climatological data revealed a rise in environmental temperature and relative humidity during the study that coincides with the increase of malaria cases, since it creates favorable mosquito breeding for malaria transmission in the city. P. vivax was found as a predominant species in causing malaria burden indicating its public health problem in Adama city affecting the productive age group of the community, adolescents and adults, during the minor transmission season of malaria. In addition to its public health importance by causing morbidity and mortality such kind of scenario may also exacerbates poverty.

Comparison of infectivity of Plasmodium vivax to wild-caught and laboratory-adapted (colonized) Anopheles arabiensis mosquitoes in Ethiopia

BACKGROUND

Mosquito-feeding assays that assess transmission of Plasmodium from man-to-mosquito typically use laboratory mosquito colonies. The microbiome and genetic background of local mosquitoes may be different and influence Plasmodium transmission efficiency. In order to interpret transmission studies to the local epidemiology, it is therefore crucial to understand the relationship between infectivity in laboratory-adapted and local mosquitoes.

METHODS

We assessed infectivity of Plasmodium vivax-infected patients from Adama, Ethiopia, using laboratory-adapted (colony) and wild-caught (wild) mosquitoes raised from larval collections in paired feeding experiments. Feeding assays used 4-6 day-old female Anopheles arabiensis mosquitoes after starvation for 12 h (colony) and 18 h (wild). Oocyst development was assessed microscopically 7 days post-feeding. Wild mosquitoes were identified morphologically and confirmed by genotyping. Asexual parasites and gametocytes were quantified in donor blood by microscopy.

RESULTS

In 36 paired experiments (25 P. vivax infections and 11 co-infections with P. falciparum), feeding efficiency was higher in colony (median: 62.5%; interquartile range, IQR: 47.0-79.0%) compared to wild mosquitoes (median: 27.8%; IQR: 17.0-38.0%; Z = 5.02; P < 0.001). Plasmodium vivax from infectious individuals (51.6%, 16/31) infected a median of 55.0% (IQR: 6.7-85.7%; range: 5.5-96.7%; n = 14) of the colony and 52.7% (IQR: 20.0-80.0%; range: 3.2-95.0%; n = 14) of the wild mosquitoes. A strong association (ρ(16) = 0.819; P < 0.001) was observed between the proportion of infected wild and colony mosquitoes. A positive association was detected between microscopically detected gametocytes and the proportion of infected colony (ρ(31) = 0.452; P = 0.011) and wild (ρ(31) = 0.386; P = 0.032) mosquitoes.

CONCLUSIONS

Infectivity assessments with colony and wild mosquitoes yielded similar infection results. This finding supports the use of colony mosquitoes for assessments of the infectious reservoir for malaria in this setting whilst acknowledging the importance of mosquito factors influencing sporogonic development of Plasmodium parasites.