Assessment of microfilaremia in 'hotspots' of four lymphatic filariasis endemic districts of Nepal during post-MDA surveillance.

BACKGROUND: The lymphatic filariasis (LF) elimination program in all sixty-three endemic districts of Nepal was based on annual mass drug administration (MDA) using a combination of diethylcarbamazine (DEC) and albendazole for at least 5 years. The MDA program was started in the Parsa district of the Terai region and at least six rounds of MDA were completed between 2003 and 2017 in all filariasis endemic districts of Central Nepal. Transmission Assessment Survey (TAS) report indicated that circulating filarial antigen (CFA) prevalence was below the critical value i.e., ≤ 2% in selected LF endemic districts of Central Nepal. Based on the TAS report, antigen-positive cases were found clustered in the foci of those districts which were considered as "hotspots". Hence the present study was designed to assess microfilaremia in hotspots of four endemic districts of Central Nepal after the MDA program. METHODOLOGY AND PRINCIPAL FINDINGS: The present study assessed microfilaremia in hotspots of four endemic districts i.e. Lalitpur and Dhading from the hilly region and Bara and Mahottari from the Terai region of Central Nepal. Night blood samples (n = 1722) were collected by finger prick method from the eligible sample population irrespective of age and sex. Community people's participation in the MDA program was ensured using a structured questionnaire and chronic clinical manifestation of LF was assessed using standard case definition. Two districts one each from the hilly region (Lalitpur district) and Terai region (Bara district) showed improved microfilaria (MF) prevalence i.e. below the critical level (<1%) while the other two districts are still over the critical level. There was a significantly high prevalence of MF in male (p = <0.05) and ≥41 years of age group (p = <0.05) community people in the hotspots of four endemic districts. People who participated in the previous rounds of the MDA program have significantly low MF prevalence. The upper confidence limit of MF prevalence in all hotspots of four districts was above the critical level (>1%). Chronic clinical manifestation of LF showed significant association with the older age group (≥41 years) but not with sex. CONCLUSIONS: The study revealed LF transmission improved in hotspots of two districts while continued in others but the risk of LF resurgence cannot be ignored since the upper confidence level of MF prevalence is over 1% in all the hotspots studied districts. High MF prevalence is well correlated with the number of MDA rounds but not with the MDA coverage. Community people involved in MDA drug uptake in any previous and last rounds have significantly less MF infection. Hence it is recommended that before deciding to stop the MDA rounds it is essential to conduct the MF survey at the hotspots of the sentinel sites.

Feasibility and comparative analysis of Dirofilaria immitis microfilaria freezing and fixation for student instruction and assessment of clinical parasitology skills.

BACKGROUND: Detection of D. immitis microfilaria (mf) is an important diagnostic skill in veterinary medicine and is critical to Day 1 veterinarians and technicians. Finding a supply of blood containing mf to teach the technique and formalin's adverse environmental effects used in the diagnostic microscopic tests present a challenge. RESULTS: This study evaluated the use of cryopreserved and recently drawn mf-infected blood along with two fixative reagents, acetic acid or formalin for mf detection. The specific aims included determining if veterinary students could 1) detect cryopreserved mf added to fresh blood using routine diagnostic testing and 2) detect morphological differences in the mf. The 236 students were kept blind from the sample status. The ability of the students to identify mf and the mf morphology were compared for the samples and fixatives evaluated. The results demonstrate using a combination of cryopreservation and acetic acid for teaching microfilaria diagnostic techniques is fleasible; however, the quality of the mf morphology is less than optimal when compared to freshly acquired mf containing blood. Compared to reference values, the mf demonstrated a decrease in size with each additional variable evaluated. CONCLUSION: A majority (98.3%) of the 236 students correctly identified the presence of mf. Teaching laboratories could utilize cryopreserved mf-spiked donor blood in lieu of freshly collected mf-containing blood from a naturally or experimentally infected dog. Substitution of less hazardous chemicals for the fixative can be used. Finally, the change in size measurements provides a mechanism to ensure students can correctly measure mf as students are required to do verifiable measurements and cannot copy reference values from a text book since the cryopreservation and fixation methods cause the mf to measure smaller than textbook reference values.

Continuous and pulsed epidemiological models for onchocerciasis with implications for eradication strategy.

Onchocerciasis is an endemic disease in parts of sub-Saharan Africa. Complex mathematical models are being used to assess the likely efficacy of efforts to eradicate the disease; however, their predictions have not always been borne out in practice. In this paper, we represent the immunological aspects of the disease with a single empirical parameter in order to reduce the model complexity. Asymptotic approximation allows us to reduce the vector-borne epidemiological model to a model of an infectious disease with nonlinear incidence. We then consider two versions, one with continuous treatment and a more realistic one where treatment occurs only at intervals. Thorough mathematical analysis of these models yields equilibrium solutions for the continuous case, periodic solutions for the pulsed case, and conditions for the existence of endemic disease equilibria in both cases, thereby leading to simple model criteria for eradication. The analytical results and numerical experiments show that the continuous treatment version is an excellent approximation for the pulsed version and that the current onchocerciasis eradication strategy is inadequate for regions where the incidence is highest and unacceptably slow even when the long-term behavior is the disease-free state.

Diagnosing risk factors alongside mass drug administration using serial diagnostic tests-which test first?

Background: When tests are used in series to determine individual risk factors and infection status in a mass drug administration (MDA), the diagnostics, test order and subsequent treatment decisions (the testing algorithm) affect population-level treatment coverage and cost, but there is no existing framework for evaluating which algorithm optimizes any given outcome. Methods: We present a mathematical tool (with spreadsheet implementation) to analyse the effect of test ordering, illustrated using treatment for onchocerciasis in an area where high-burden Loa loa co-infections present a known risk factor. Results: The prevalence of the infection and risk factor have a non-linear impact on the optimal ordering of tests. Testing for the MDA infection first always leaves more infected people untreated but fewer people with the risk factor being misclassified. The cost of the treatment given to infected individuals with the risk factor does not affect which algorithm is more cost effective. Conclusions: For a given test and treat algorithm and its costs, the correct strategy depends on the expected prevalence. In most cases, when the apparent prevalence of the target infection is greater than the apparent prevalence of the risk factor, it is cheaper to do the risk factor test first, and vice versa.

Twelve-month longitudinal parasitological assessment of lymphatic filariasis-positive individuals: impact of a biannual treatment with ivermectin and albendazole.

OBJECTIVE: Mass drug administration (MDA) for the control of lymphatic filariasis (LF), in Ghana, started in the year 2000. While this had great success in many implementation units, there remain areas with persistent transmission, after more than 10 years of treatment. A closer examination of the parasite populations could help understand the reasons for persistent infections and formulate appropriate strategies to control LF in these areas of persistent transmission. MATERIALS AND METHODS: In a longitudinal study, we assessed the prevalence of microfilaraemia (mf) in two communities with 12 years of MDA in Ghana. In baseline surveys 6 months after the National MDA in 2014, 370 consenting individuals were tested for antigenaemia using immunochromatographic test (ICT) cards and had their mf count determined through night blood surveys. 48 ICT positives, of whom, 17 were positive for mf, were treated with 400 µg/kg ivermectin + 400 mg albendazole and subsequently followed for parasitological assessment at 3-month intervals for 1 year. This overlapped with the National MDA in 2015. RESULTS: There was a 68% parasite clearance 3 months after treatment. The pre-treatment mf count differed significantly from the post-treatment mf counts at 3 months (P = 0.0023), 6 months (P = 0.0051), 9 months (P = 0.0113) and 12 months (P = 0.0008). CONCLUSION: In these settings with persistent LF transmission, twice-yearly treatment may help accelerate LF elimination. Further large-scale evaluations are required to ascertain these findings.

Assessment of parasitological findings in heartworm-infected beagles treated with Advantage Multi® for dogs (10% imidacloprid + 2.5% moxidectin) and doxycycline.

BACKGROUND: Anecdotal reports support the position that the adulticidal heartworm treatment utilizing doxycycline and Advantage Multi®/Advocate® for Dogs (10% imidacloprid + 2.5% moxidectin) has successfully converted antigen-positive dogs to antigen-negative. To date, no controlled experimental studies have demonstrated the adulticidal efficacy of this treatment regimen. The aim of this study was to evaluate the parasitological and clinical efficacy of Advantage Multi® for Dogs (IMD + MOX) and doxycycline in heartworm-infected beagles. METHODS: This study utilized 16 dogs, 8 dogs in each of non-treated control and treated groups. A total of 16 adult Dirofilaria immitis (Missouri strain) were surgically transplanted into the jugular vein of each study dog. The treatment regimen of monthly IMD + MOX topically (per labeled dosage and administration) for 10 months and 10 mg/kg doxycycline BID orally for 30 days was initiated 30 days post-surgical transplant. Echocardiograms, radiographs, complete blood counts, clinical chemistry profiles, heartworm antigenemia and microfilaremia were evaluated every 4 weeks. Serum samples were assayed for heartworm antigen using the DiroCHEK® heartworm antigen test. The DiroCHEK® was performed according to the manufacturer's recommendations and read using a spectrophotometer at 490 nm. RESULTS: All dogs tested positive for the presence of heartworm antigen post-surgical transplant and prior to treatment. Heartworm antigen levels began declining in treated dogs 3 months post-treatment. Non-treated control dogs remained antigen-positive. No microfilariae were detected in treated dogs after 21 days post-treatment. At necropsy, adult heartworms were recovered from all non-treated control dogs with a range of 10-12 adult worms/dog for an average recovery of 10.6 adult heartworms/dog. In the IMD + MOX- and doxycycline-treated dogs, the range of adult heartworms recovered was 0-2 adult worms/dog, with five dogs having no adult heartworms present. The average adult heartworm recovery was 0.6/dog in the treated group. This treatment regimen demonstrated a 95.9% efficacy in eliminating adult heartworms (P < 0.0001). CONCLUSIONS: This study demonstrated that this treatment regimen successfully eliminated D. immitis microfilariae by 21 days post-treatment, reduced heartworm antigen concentration over time, and had a 95.9% efficacy in the elimination of mature adult heartworms. Based on this study, we conclude that this treatment regimen is a relatively quick, reliable and safe option to treat canine heartworm infection as compared to other treatment regimens involving macrocyclic lactones, when the approved drug melarsomine dihydrochloride is unavailable, contraindicated or declined by an owner unable to afford the more costly treatment or concerned about the potential side effects.

Progress towards onchocerciasis elimination in the participating countries of the African Programme for Onchocerciasis Control: epidemiological evaluation results.

BACKGROUND: The African Programme for Onchocerciasis Control (APOC) was created in 1995 to establish community-directed treatment with ivermectin (CDTi) in order to control onchocerciasis as a public health problem in 20 African countries that had 80 % of the global disease burden. When research showed that CDTi may ultimately eliminate onchocerciasis infection, APOC was given in 2008 the additional objective to determine when and where treatment can be safely stopped. We report the results of epidemiological evaluations undertaken from 2008 to 2014 to assess progress towards elimination in CDTi areas with ≥6 years treatment. METHODS: Skin snip surveys were undertaken in samples of first-line villages to determine the prevalence of O. volvulus microfilariae. There were two evaluation phases. The decline in prevalence was evaluated in phase 1A. Observed and model-predicted prevalences were compared after correcting for endemicity level and treatment coverage. Bayesian statistics and Monte Carlo simulation were used to classify the decline in prevalence as faster than predicted, on track or delayed. Where the prevalence approached elimination levels, phase 1B was launched to determine if treatment could be safely stopped. Village sampling was extended to the whole CDTi area. Survey data were analysed within a Bayesian framework to determine if stopping criteria (overall prevalence <1.4 % and maximum stratum prevalence <5 %) were met. RESULTS: In phase 1A 127 665 people from 639 villages in 54 areas were examined. The prevalence had fallen dramatically. The decline in prevalence was faster than predicted in 23 areas, on track in another 23 and delayed in eight areas. In phase 1B 108 636 people in 392 villages were examined in 22 areas of which 13 met the epidemiological criteria for stopping treatment. Overall, 32 areas (25.4 million people) had reached or were close to elimination, 18 areas (17.4 million) were on track but required more years treatment, and in eight areas (10.4 million) progress was unsatisfactory. CONCLUSIONS: Onchocerciasis has been largely controlled as a public health problem. Great progress has been made towards elimination which already appears to have been achieved for millions of people. For most APOC countries, nationwide onchocerciasis elimination is within reach.

Can community-based integrated vector control hasten the process of LF elimination?

Community-based integrated vector control (IVC) using polystyrene beads (EPS) and pyrethroid impregnated curtains (PIC) as an adjunct to mass drug administration (MDA) was implemented for lymphatic filariasis elimination, in the filaria endemic villages of Tirukoilur, south India. In all the villages, MDA was carried out by the state health machinery, as part of the national filariasis elimination programme. Thirty-six difficult-to-control villages were grouped as, viz, MDA alone, MDA + EPS and MDA + EPS + PIC arms. Implementation and monitoring of IVC was carried out by the community. After 3 years of IVC, higher reductions in filariometric indices were observed in both the community and vector population. Decline in antigenaemia prevalence was higher in MDA + IVC as compared to MDA alone arm. Vector density dropped significantly (P < 0.05) in both the IVC arms, and nil transmission was observed during post-IVC period. Almost 53.8 and 75.8 % of the cesspits in MDA + EPS and MDA + EPS + PIC arms were closed by the householders, due to the enhanced awareness on vector breeding. The paper presents the key elements of IVC implementation through social mobilization in a LF prevalent area. Thus, community-based IVC strategy can hasten LF elimination, as it reduced the transmission and filariometric indices significantly. Indices were maintained at low level with nil transmission, by the community through IVC tools.

[Lymphatic filariasis transmission assessment survey in schools three years after stopping mass drug treatment with albendazole and ivermectin in the 7 endemic districts in Togo]. / Enquête d'évaluation de la transmission de la filariose lymphatique en milieu scolaire, 3 ans après l'arrêt du traitement de masse à l'albendazole et à l'ivermectine dans les 7 districts endémiques du Togo.

The aim of this study is to verify the level of transmission of lymphatic filariasis three years after stopping mass drug treatment in the 7 endemic districts in Togo. The survey was conducted in 2012 in Togo's 7 endemic districts grouped into four evaluation units (EU) using the WHO-recommended transmission assessment survey (TAS) protocol. Children aged 6-7 years were screened for Wuchereria bancofti antigen using the immunochromatographic card (ICT) method. A cluster sampling method was used to select eligible children in schools as the net primary-school enrolment ratio is greater than or equal to 75% in each of the four EUs. The number of children and schools to be selected in each EU, the randomization list for the selection of these children and the critical cut-off number of positive cases not to exceed were automatically generated using the Survey Sample Builder (SSB) tool, (NTD Support Center, Atlanta, Ga, USA). For confirmation, positive cases were subsequently tested for microfilaremia using nocturnal thick blood smear and for filarial antigen using Og4C3 antigen ELISA (TropBio ELISA Kit®, Townsville, Queensland, Australia). An EU is considered to have passed the test successfully (it is assumed that transmission can no longer be sustained), when the number of positive cases is below the critical cut-off number set by the SSB, which is roughly equivalent to 2% prevalence. Of the 1 706 children surveyed in Kpendjal-Tone's EU, 1 549 in Binah-Doufelgou's EU, 1 550 in Kozah's EU and the 1 575 in Amou-Haho's EU, 8 (0.46%), 1 (0.08%), 0 (0.00%) and 4 (0.25%) ICT positive cases respectively were detected. The number of positive ICT tests was well below 18, the critical cut number for each of the 4 EUs. All 13 ICT positive cases tested negative for nocturnal microfilaremia and Og4C3 ELISA. We conclude that all four EU passed the TAS with success, and the transmission of Wuchereria bancrofti is no longer likely to be sustained in the 7 endemic districts in Togo 3 years after stopping the MDA. A new TAS will be carried out in 2015, after which, if the results are still good, the country will submit a dossier to WHO for verification of the elimination of lymphatic filariasis.

A comprehensive assessment of lymphatic filariasis in Sri Lanka six years after cessation of mass drug administration.

BACKGROUND: The Sri Lankan Anti-Filariasis Campaign conducted 5 rounds of mass drug administration (MDA) with diethycarbamazine plus albendazole between 2002 and 2006. We now report results of a comprehensive surveillance program that assessed the lymphatic filariasis (LF) situation in Sri Lanka 6 years after cessation of MDA. METHODOLOGY AND PRINCIPAL FINDINGS: Transmission assessment surveys (TAS) were performed per WHO guidelines in primary school children in 11 evaluation units (EUs) in all 8 formerly endemic districts. All EUs easily satisfied WHO criteria for stopping MDA. Comprehensive surveillance was performed in 19 Public Health Inspector (PHI) areas (subdistrict health administrative units). The surveillance package included cross-sectional community surveys for microfilaremia (Mf) and circulating filarial antigenemia (CFA), school surveys for CFA and anti-filarial antibodies, and collection of Culex mosquitoes with gravid traps for detection of filarial DNA (molecular xenomonitoring, MX). Provisional target rates for interruption of LF transmission were community CFA <2%, antibody in school children <2%, and filarial DNA in mosquitoes <0.25%. Community Mf and CFA prevalence rates ranged from 0-0.9% and 0-3.4%, respectively. Infection rates were significantly higher in males and lower in people who denied prior treatment. Antibody rates in school children exceeded 2% in 10 study sites; the area that had the highest community and school CFA rates also had the highest school antibody rate (6.9%). Filarial DNA rates in mosquitoes exceeded 0.25% in 10 PHI areas. CONCLUSIONS: Comprehensive surveillance is feasible for some national filariasis elimination programs. Low-level persistence of LF was present in all study sites; several sites failed to meet provisional endpoint criteria for LF elimination, and follow-up testing will be needed in these areas. TAS was not sensitive for detecting low-level persistence of filariasis in Sri Lanka. We recommend use of antibody and MX testing as tools to complement TAS for post-MDA surveillance.

Avaliação epidemiológica de doenças negligenciadas em escolares: filariose linfática e parasitoses intestinais / Epidemiological assessment of neglected diseases in children: lymphatic filariasis and soil-transmitted helminthiasis

OBJETIVO: Descrever a prevalência de infecção filarial e de parasitoses intestinais em escolares numa área endêmica de filariose e refletir sobre a opção terapêutica utilizada no Brasil no tratamento coletivo para filariose. MÉTODOS: Estudo transversal envolvendo 508 alunos na faixa etária de 5-18 anos cadastrados em escolas públicas do município de Olinda-PE. Realizou-se a investigação da parasitose intestinal em três amostras de fezes, analisadas pelo método de Hoffmann, Pons e Janer. A investigação filarial foi feita com teste antigênico pela técnica de imunocromatográfica rápida (ICT) e pesquisa de microfilárias, utilizando filtração em membrana de policarbonato. Para análise de dados utilizou-se a estatística descritiva através do programa EpiInfo versão 7. RESULTADOS: A prevalência de filariose por ICT foi de 13,8% e por microfilaremia de 1,2%, enquanto a de parasitoses intestinais foi 64,2%. A concomitância do diagnóstico filarial e de parasitoses intestinais foi de 9,4% e, 31,5% eram isentos de ambas as parasitoses. Entre os indivíduos com parasitoses intestinais, 55% eram monoparasitados e 45% poliparasitados. A presença de geohelmintos ocorreu em 72,5% dos parasitados. No grupo com infecção filarial a ocorrência de geohelmintíase foi de 54,5%. CONCLUSÕES: O diagnóstico simultâneo de infecção filarial e parasitose intestinal, bem como a elevada frequência de geohelmintos justificam uma reavaliação da estratégia terapêutica do tratamento coletivo no programa de filariose no Brasil.

OBJECTIVE: To report the prevalence of lymphatic filariasis and intestinal parasitic infections in school-aged children living in a filariasis endemic area and discuss about the therapeutic regimen adopted in Brazil for the large-scale treatment of filariasis. METHODS: A cross-sectional study including 508 students aged 5-18 years old, enrolled in public schools within the city of Olinda, Pernambuco. The presence of intestinal parasites was analyzed using the Hoffman, Pons and Janer method on 3 stool samples. The diagnosis of filarial infection was performed using the rapid immunochromatographic technique (ICT) for the antigen, and the polycarbonate membrane filtration for the presence of microfilariae. Descriptive statistics of the data was performed using EpiInfo version 7. RESULTS: The prevalence of filariasis was 13.8% by ICT and 1.2% by microfilaraemia, while intestinal parasites were detected in 64.2% of cases. Concurrent diagnosis of filariasis and intestinal parasites was 9.4%, while 31.5% of students were parasite-free. Among individuals with intestinal parasites, 55% had one parasite and 45% had more than one parasite. Geohelminths occurred in 72.5% of the parasited individuals. In the group with filarial infection the prevalence of soil-transmitted helminthiasis was 54.5%. CONCLUSIONS: The simultaneous diagnosis of filariasis and intestinal parasites as well as the high frequency of geohelminths justify the need to reevaluate the treatment strategy used in the Brazilian filariasis large-scale treatment program.

Epidemiological assessment of neglected diseases in children: lymphatic filariasis and soil-transmitted helminthiasis.

OBJECTIVE: To report the prevalence of lymphatic filariasis and intestinal parasitic infections in school-aged children living in a filariasis endemic area and discuss about the therapeutic regimen adopted in Brazil for the large-scale treatment of filariasis. METHODS: A cross-sectional study including 508 students aged 5-18 years old, enrolled in public schools within the city of Olinda, Pernambuco. The presence of intestinal parasites was analyzed using the Hoffman, Pons and Janer method on 3 stool samples. The diagnosis of filarial infection was performed using the rapid immunochromatographic technique (ICT) for the antigen, and the polycarbonate membrane filtration for the presence of microfilariae. Descriptive statistics of the data was performed using EpiInfo version 7. RESULTS: The prevalence of filariasis was 13.8% by ICT and 1.2% by microfilaraemia, while intestinal parasites were detected in 64.2% of cases. Concurrent diagnosis of filariasis and intestinal parasites was 9.4%, while 31.5% of students were parasite-free. Among individuals with intestinal parasites, 55% had one parasite and 45% had more than one parasite. Geohelminths occurred in 72.5% of the parasited individuals. In the group with filarial infection the prevalence of soil-transmitted helminthiasis was 54.5%. CONCLUSIONS: The simultaneous diagnosis of filariasis and intestinal parasites as well as the high frequency of geohelminths justify the need to reevaluate the treatment strategy used in the Brazilian filariasis large-scale treatment program.

Monitoring and evaluation of lymphatic filariasis interventions: an improved PCR-based pool screening method for high throughput Wuchereria bancrofti detection using dried blood spots.

BACKGROUND: Effective diagnostic tools are necessary to monitor and evaluate interruption of Lymphatic Filariasis (LF) transmission. Accurate detection of Wuchereria bancrofti (Wb) microfilaria (mf) is essential to measure the impact of community treatment programmes. PCR-based assays are specific, highly sensitive tools allowing the detection of Wuchereria bancrofti DNA in human blood samples. However, current protocols describing the pool screening approach, use samples of less than 60 µl of blood, which limits the sensitivity of the pool-screen PCR assay. The purpose of this study was to improve the pool-screen PCR protocol to enhance its sensitivity and usefulness for population scale studies. FINDINGS: DNA extractions were performed with the DNeasy kit, the PCR with the Wb LDR primers and the SYBR-Green dye. Improvements of our pool-screen real-time PCR (qPCR) assay allowed the detection of as little as one Wb microfilaria diluted in a pool of at least 12 blood samples of 60 µl each. Using this assay, mf burdens can be predicted using a standard curve derived from mf spiked dried blood samples. The sensitivity achieved is equivalent to the detection of a single LF positive individual carrying a mf burden as low as 18 mf/ml, in a pool of blood samples from at least 12 individuals. CONCLUSIONS: Due to its sensitivity, rapidity and cost-effectiveness, we suggest this qPCR pool-screening assay could be used as a diagnostic tool for population- scale filariasis elimination monitoring and evaluation.

Extracts of Euphorbia hirta Linn. (Euphorbiaceae) and Rauvolfia vomitoria Afzel (Apocynaceae) demonstrate activities against Onchocerca volvulus microfilariae in vitro.

BACKGROUND: Onchocerciasis transmitted by Onchocerca volvulus is the second major cause of blindness in the world and it impacts negatively on the socio-economic development of the communities affected. Currently, ivermectin, a microfilaricidal drug is the only drug recommended for treating this disease. There have been speculations, of late, concerning O. volvulus resistance to ivermectin. Owing to this, it has become imperative to search for new drugs. World-wide, ethnomedicines including extracts of Euphorbia hirta and Rauvolfia vomitoria are used for treating various diseases, both infectious and non-infectious. METHOD: In this study extracts of the two plants were evaluated in vitro in order to determine their effect against O. volvulus microfilariae. The toxicity of the E. hirta extracts on monkey kidney cell (LLCMK2) lines was also determined. RESULTS: The investigations showed that extracts of both plants immobilised microfilariae at different levels in vitro and, therefore, possess antifilarial properties. It was found that all the E. hirta extracts with the exception of the hexane extracts were more effective than those of R. vomitoria. Among the extracts of E. hirta the ethyl acetate fraction was most effective, and comparable to that of dimethanesulphonate salt but higher than that of Melarsoprol (Mel B). However, the crude ethanolic extract of E. hirta was found to be the least toxic to the LLCMK2 compared to the fractionated forms. CONCLUSIONS: Extracts from both plants possess antifilarial properties; however, the crude extract of E. hirta was found to be least toxic to LLCMK2.

Predictive value of the eosinophil counts in the biological diagnosis of lymphatic filariasis in French Polynesia.

SETTINGS: Lymphatic filariasis is common in many tropical and subtropical areas and is a major public health issue in south Pacific islands. In endemic areas, most infected individuals are asymptomatic but may harbor microfilariae or filarial antigens in their peripheral blood. Microscopy remains the reference diagnostic tool for the identification of microfilariae but is weakly sensitive. The diagnosis of Wuchereria bancrofti infection was dramatically altered by the development of filarial antigen tests, which are easy to perform but expensive for routine use. Lymphatic filariasis is responsible for acquired eosinophilia and blood eosinophil count is commonly used as a screening tool in endemic areas. METHOD: We retrospectively analyzed all the results of eosinophil counts, antigen and microfilariae detection performed in our laboratory over a 24-month period. We calculated the prevalence of antigenemia for various eosinophilic cut offs. RESULTS: The prevalence of antigenemia was estimated at 25.78% with eosinophilia defined as a count eosinophilic PMN above 500 per mm(3). DISCUSSION: Our prevention strategy against lymphatic filariasis is based on annual mass drug administration, vector control, and systematic treatment of antigenemic and microfilaremic patients. Antigenemic and microfilaremic detection cannot be routinely performed because of their cost. Current treatments used for lymphatic filariasis are safe and cheaper than antigenic detection. A possible additional strategy to decrease the prevalence of antigenemia would be the systematic treatment of patients with hypereosinophilia.

Validation of the rapid assessment procedure for loiasis (RAPLOA) in the Democratic Republic of Congo.

BACKGROUND: A simple method called RAPLOA, to rapidly assess what proportion of people in a community are infected with L. loa and hence which communities are at high risk of severe adverse reactions following ivermectin treatment, was developed in Cameroon and Nigeria. The method needed further validation in other geographical and cultural contexts before its application in all endemic countries. The present study was designed to validate RAPLOA in two regions in the North East and South West of the Democratic Republic of Congo. METHODS: In each study region, villages were selected from different bio-ecological zones in order to cover a wide range of loiasis endemicity. In each selected community, 80 people above the age of 15 years were interviewed for a history of eye worm (migration of adult L. loa under the conjunctiva of the eye) and parasitologically examined for the presence and intensity of L. loa infection. In total, 8100 individuals from 99 villages were enrolled into the study. RESULTS: The results confirmed the findings of the original RAPLOA study: i) the eye worm phenomenon was well-known in all endemic areas, ii) there was a clear relationship between the prevalence of eye worm history and the prevalence and intensity of L. loa microfilaraemia, and iii) using a threshold of 40%, the prevalence of eye worm history was a sensitive and specific indicator of high-risk communities. CONCLUSION: Following this successful validation, RAPLOA was recommended for the assessment of loiasis endemicity in areas targeted for ivermectin treatment by lymphatic filariasis and onchocerciasis control programmes.

Current practices in the management of lymphatic filariasis.

Lymphatic filariasis is a major cause of acute and chronic morbidity in 81 countries. The availability of safe treatment regimens along with rapid diagnostic tools resulted in a global program to eliminate the disease. The two main objectives of the global elimination program are to interrupt transmission of the parasites and to provide care for those with the disease. The strategy for transmission interruption is preventive chemotherapy through mass drug administration. This article reviews the current treatment regimens for lymphatic filariasis and discusses the challenges posed by co-endemicity with other diseases. The role of integrated vector management as a supplementary strategy for mass drug administration and new strategies for treatment and morbidity control through antibiotic targeting of the Wolbachia endosymbionts are also discussed.

Independent assessment of Mass Drug Administration in filariasis affected Surat city.

The Mass Drug Administration (MDA) done in Surat city (Gujarat) during 2005, revealed good impact on infection and infectivity in mosquitoes and also on microfilaria rate & mean infection density. The overall impact seen was 23% on mf rate, 28% on mean mf density, 65% on infection rate and 50% on infectivity rate in vectors. Indigenous population contribution to microfilaria cases was 9.7%, whereas migratory population contributed 72.2%; predominant 51.9% from Orissa and 20.3% from U.P. Of the total 3640 persons interviewed for MDA compliance in seven zones of the Surat city revealed that actual drug consumption was 76.7% (2792/3640). Another 11.9% although took the drug but did not consume and 11.4% refused. Important reasons for consuming was fear to get the disease (40.7%) and for not consuming; 'will consume after meal' (6.9%), too many tablets (1.7%), seek consent from doctor (1.5%), lack of awareness (1.4%) etc. Refusal was mainly due to the reason as respondents felt apparently healthy. Assessment of IEC activities suggested that main awareness was created by media (local or national TV, banners or handbills, local news papers or mike announcement) alongwith some impact made through NGO's. These observations clearly indicated the utility of effective health education for optimum community participation and shown that it was crucial for successful community based elimination campaign. However some gray areas also suggest the scope for further improvements.

The Leogane, Haiti demonstration project: decreased microfilaremia and program costs after three years of mass drug administration.

To support the global program to eliminate lymphatic filariasis (LF), well-monitored demonstration projects are important for defining the relationship between coverage and reductions in microfilaremia. We are using mass treatment with diethylcarbamazine (DEC) and albendazole in an effort to eliminate LF from Leogane, Haiti. Wuchereria bancrofti microfilaremia prevalence at baseline ranged from 0.8% to 15.9% in four sentinel sites. After three rounds of DEC-albendazole mass drug administration (MDA), both microfilaremia prevalence and intensity decreased dramatically. Mild and moderate adverse reactions after treatment were common, especially after the first MDA, but decreased after subsequent MDAs. Drug coverage for the first year was estimated to be 72%, but concerns about adverse reactions appeared to decrease drug coverage in the second MDA. As a result of community education efforts that focused on providing a greater understanding of adverse reactions, coverage increased dramatically for the third round. Program efficiency increased substantially; the costs per person treated for three rounds of MDA were 2.23 US dollars, 1.96 US dollars, and 1.30 US dollars per person, respectively. The Leogane experience highlights the importance of adapting community education and mobilization campaigns to achieve and maintain good coverage.

Rapid assessment of the geographical distribution of Mansonella perstans infections in Uganda, by screening schoolchildren for microfilariae.

The geographical distribution of Mansonella perstans infections in Uganda was assessed by day-time examination of school-aged children for microfilariae. Overall, 12,207 children from 76 sites representing the various topographical and ecological zones in the country were examined. Children with M. perstans microfilaraemia were detected at 47 (61.8%) of the study sites, with prevalences ranging from 0.4% to 72.8%. A broad, east-west-oriented belt of high endemicity was identified, stretching across the central part of the country from the southern end of Lake Albert to the north-western shores of Lake Victoria. To the north and south of this belt prevalences generally decreased, although high-prevalence foci were also identified in the far north-western and south-eastern corners of the country. Geostatistical interpolation was used to create a map showing the geographical distribution of M. perstans prevalences in Uganda (by ordinary kriging), and to assess the population exposed to M. perstans transmission. Estimates based on population data from 2002 indicated that 20.4 million people (82.6% of the national population) and 6.8 million people (27.5% of the national population) lived in areas where, respectively, >1% and >10% of the school-aged children had M. perstans microfilaraemias. Since the prevalence of M. perstans microfilaraemia is known to increase with age, the overall population prevalences are likely to be even higher than the prevalences observed in the school-aged children. More attention needs to be paid to the public-health implications of this wide-spread but neglected infection.