Shrinking the Lymphatic Filariasis Map of Ethiopia: Reassessing the Population at Risk through Nationwide Mapping

Rebollo, Maria P.; Sime, Heven; Assefa, Ashenafi; Cano, Jorge; Deribe, Kebede; González-Escalada, Alba; Shafi, Oumer; Davey, Gail; Brooker, Simon; Kebede, Amha; Bockarie, Moses J.

doi:10.1371/journal.pntd.0004172

Cited by 26 publications

(36 citation statements)

References 15 publications

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“…In recent years, puzzling results have emerged from ICT-based LF mapping surveys conducted in central Africa, raising questions about the validity of LF distribution maps and current estimates of the prevalence of infection in this subregion 1,2…”

Section: Introductionmentioning

confidence: 99%

Positivity of Antigen Tests Used for Diagnosis of Lymphatic Filariasis in Individuals Without Wuchereria bancrofti Infection But with High Loa loa Microfilaremia

Pion

Montavon

Chesnais

et al. 2016

The American Society of Tropical Medicine and Hygiene

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Since the mid-2000s, the immunochromatographic card test (ICT), a point-of-care test for detecting Wuchereria bancrofti circulating filarial antigens (CFAs), has been the backbone for mapping and monitoring lymphatic filariasis (LF) worldwide. Recently, there have been instances in which CFA positivity has been associated with Loa loa microfilaremia. Here, we examined the association, at both the community and individual levels, between L. loa and CFA using additional diagnostic tools (quantitative polymerase chain reaction [qPCR], Og4C3 enzyme-linked immunosorbent assay, and IgG4 antibodies to Wb123 assays) to demonstrate the relationship between L. loa microfilaremia and ICT positivity. In May 2013, peripheral blood was collected during the day from 1,812 individuals living in southern Cameroon. ICT tests were done on the spot, and positive individuals were resampled at night. Results of qPCR and Wb123 assays concurred proving the absence of W. bancrofti infection. Og4C3 assays indicate a quantitative relationship between the level of L. loa microfilaremia and that of CFA. This was confirmed by epidemiological analyses, which reveal a strong association between L. loa microfilaremia and ICT positivity, with 50% of ICT reacting to L. loa when its microfilarial density exceeds 30,000 microfilariae/mL. At the community level, the proportion of positive ICT would exceed 2% when the prevalence of L. loa microfilaremia in the total population is above 20%. This has significant implications in terms of mapping and control of LF caused by W. bancrofti in Loa-endemic areas. Cross-reactivity of ICT with L. loa has to be considered in the context of both individual and community diagnostics.

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Section: Introductionmentioning

confidence: 99%

Positivity of Antigen Tests Used for Diagnosis of Lymphatic Filariasis in Individuals Without Wuchereria bancrofti Infection But with High Loa loa Microfilaremia

Pion

Montavon

Chesnais

et al. 2016

The American Society of Tropical Medicine and Hygiene

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“…The coverage in school age children (5)(6)(7)(8)(9)(10)(11)(12)(13)(14) shows significant difference with treatment coverage in individuals aged 15 and above (p<0.001) in the last mass drug administration campaign and this fact can be explained by the fact that most of the respondents were school age children and that there was a wrong assumption that the treatment is not given for adults while the treatment strategy include all individuals aged 5 and above and other reasons were also considered such as change of living area and not being around during the mass drug administration.…”

Section: Discussionmentioning

confidence: 99%

“…LF is one of the most debilitating and disfiguring diseases common in Ethiopia and in this country is caused by Wuchereria bancrofti (4). Anopheles species of mosquitoes are the main vectors for LF transmission in Ethiopia (5).…”

Section: Introductionmentioning

confidence: 99%

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Coverage Validation survey for lymphatic filariasis treatment in Itang special district of Gambella regional state of Ethiopia; Cross sectional study

Teshome

Zerdo

Asnakew

et al. 2020

Preprint

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Background Coverage validation survey provides a more precise estimate of preventive chemotherapy coverage and avoids the biases, as well as some of the errors that can affect reported coverage. This coverage validation survey was done to know the difference between the reported coverage from district of Itang special for Ivermectin and Albendazole given for Lymphatic Filariasis with the actual coverage in the selected district. Methods Itang special district from Gambella region was purposively selected for lymphatic filariasis treatment coverage survey. The survey was done by using segments from each district whereby 30 segments were selected from the district. The name of the kebeles and the segments where the survey was carried out were selected by using random selection method. After getting the total number of households in each selected kebele from the village chief the number of segments to be visited was computed by dividing the number of households to 50 and 16 households were visited from each segment and eligible individuals aged 5 and above were interviewed. Data for variables related to coverage of the IVM plus ALB were collected using Survey CTO software. Location of each household and the kebele chief office was recorded by using Global positioning system. Information about the kebele including population size, number of households in the kebele, last dates of mass drug administration were gathered primarily from village chiefs when available and headmasters and health extension workers when unavailable. Results The coverage validation survey result shows that the coverage for lymphatic Filariasis treatment was 81.5% in Itang special district of Gambella regional state. From 825 individuals that reported that they were offered the treatment 823(99.6%) swallowed the drug. The main reason for not being offered ivermectin and Albendazole during the mass drug administration campaigns because they were missing class during those dates (37.2%). Conclusion The data collected from Itang special woreda of Gambella Region shows that the treatment coverage is higher than the recommended coverage of 65% of the target population should be treated. Different factors play a role for this achievement including using different treatment sites such as schools, community centers and home to home by using health development armies for those children not attending schools and for nomadic communities such as the one in Gambella Regional state. Keywords Lymphatic Filariasis, Ivermectin, Albendazole, Coverage

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“…In a study conducted in an endemic zone in Ethiopia, around half of health workers interviewed inaccurately thought podoconiosis to be an infectious disease transmitted by mosquitoes, and of those who had treated podoconiosis, 71% prescribed diethylcarbamazine assuming that lymphatic filariasis (LF) was the cause 14 . Misdiagnosis of podoconiosis may not only lead to underestimation of the burden of podoconiosis, but also to underestimation of the success of LF elimination programmes, by overestimating the morbidity burden due to LF 15,16 .…”

Section: Introductionmentioning

confidence: 99%

Predicting the Environmental Suitability and Population at Risk of Podoconiosis in Africa

Deribe

Simpson

Pullan

et al. 2020

Preprint

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BackgroundPodoconiosis is a type of tropical lymphedema that causes massive swelling of the lower limbs. The disease is associated with both economic insecurity, due to long-term morbidity-related loss of productivity, and intense social stigma. The geographical distribution and burden of podoconiosis in Africa is uncertain.MethodsWe applied statistical modelling to the most comprehensive database compiled to date to predict the environmental suitability of podoconiosis in the African continent. By combining climate and environmental data and overlaying population figures, we predicted the suitability and human population at risk.ResultsIn Africa, environmental suitability for podoconiosis was predicted in 29 countries. By 2020, the total population in areas suitable for podoconiosis was estimated at 114.5 million people, (95% confidence interval: 109.4-123.9) with 16.9 million in areas suitable for both lymphatic filariasis and podoconiosis. Of the total 5,712 implementation units defined by WHO in Africa, 1,655 (29.0%) were found to be environmentally suitable for podoconiosis. The majority of IUs with high environmental suitability are located in Angola (80 IUs), Cameroon (170 IUs), the DRC (244 IUs), Ethiopia (495 IUs), Kenya (217 IUs), Uganda (116 IUs) and Tanzania (112 IUs). Of the 1,655 environmental suitable IUs, 960 (58.0%) require more detailed community-level mappingConclusionsOur estimates provide key evidence of the population at risk and geographical extent of podoconiosis in Africa, which will help decision-makers to better plan more integrated intervention programmes.

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Shrinking the Lymphatic Filariasis Map of Ethiopia: Reassessing the Population at Risk through Nationwide Mapping

Cited by 26 publications

References 15 publications

Positivity of Antigen Tests Used for Diagnosis of Lymphatic Filariasis in Individuals Without Wuchereria bancrofti Infection But with High Loa loa Microfilaremia

Positivity of Antigen Tests Used for Diagnosis of Lymphatic Filariasis in Individuals Without Wuchereria bancrofti Infection But with High Loa loa Microfilaremia

Coverage Validation survey for lymphatic filariasis treatment in Itang special district of Gambella regional state of Ethiopia; Cross sectional study

Predicting the Environmental Suitability and Population at Risk of Podoconiosis in Africa

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