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Transmission of Onchocerca volvulus (causing “river blindness”) was interrupted in two states of Nigeria (Plateau and Nasarawa) in 2017 in accordance with 2016 WHO guidelines. Ivermectin mass drug administration was halted in January 2018, and posttreatment surveillance activities were conducted over a 3-year period. Vector Simulium damnosum s.l. flies were collected during the 2019 (39 sites) and 2020 (42 sites) transmission seasons. Head pools were tested by polymerase chain reaction for the presence of third-stage O. volvulus larvae; 15,585 flies were all negative, demonstrating an infective rate of more...

Following the halt of mass drug administration (MDA) for lymphatic filariasis (LF), the WHO recommends at least 4 years of post-treatment surveillance (PTS) to confirm that transmission recrudescence or importation does not occur. The primary means of evaluation during PTS is repeated transmission assessment surveys (TASs) conducted at 2- to 3-year intervals after TAS-1 stop-MDA surveys. This study reports the results of TAS-2 and TAS-3 surveys in Plateau and Nasarawa states (pop. 6.9 million) of Nigeria divided into a minimum of seven evaluation units (EUs) per TAS. A total of 26,536 first- and second-year primary school children (approximately 6–7 years old) were tested for circulating filarial antigen (CFA) between 2014 and 2017. Of 12,313 children tested in TAS-2 surveys, only five (0.04%) were CFA positive, with no more than two positive samples from any one EU, which was below the critical value of 20 per EU. Of 14,240 children tested in TAS-3 surveys, none (0%) were CFA positive. These results indicate that LF transmission remains below sustainable transmission levels and suggest that elimination of transmission has been achieved in Plateau and Nasarawa, Nigeria. more...

Plateau and Nasarawa states in central Nigeria were endemic for onchocerciasis. The rural populations of these two states received annual ivermectin mass drug administration (MDA) for a period of 8–26 years (1992–2017). Ivermectin combined with albendazole was given for 8–13 of these years for lymphatic filariasis (LF); the LF MDA program successfully concluded in 2012, but ivermectin MDA continued in areas known to have a baseline meso-/hyperendemic onchocerciasis. In 2017, serological and entomological assessments were undertaken to determine if MDA for onchocerciasis could be stopped in accordance with the current WHO guidelines. Surveys were conducted in 39 sites that included testing 5- to < 10-year-old resident children by using ELISA for OV16 IgG4 antibodies, and Onchocerca volvulus O150 pooled polymerase chain reaction (PCR) testing of Simulium damnosum s.l. vector heads. Only two of 6,262 children were OV16 positive, and none of 19,056 vector heads were positive for parasite DNA. Therefore, both states were able to meet WHO stop-MDA thresholds of an infection rate in children of < 0.1% and a rate of infective blackflies of more...

The western region of Edo state in southern Nigeria is highly endemic for onchocerciasis. Despite years of mass drug administration (MDA) with ivermectin (IVM), reports suggest persistently high prevalence of onchocerciasis, presumably because of poor coverage. In 2016, twice-per-year treatment with IVM (combined with albendazole for lymphatic filariasis in the first round where needed) began in five local government areas (LGAs) of Edo state. We undertook a multistage cluster survey within 3 months after each round of MDA to assess coverage. First-round coverage was poor: among 4,942 people of all ages interviewed from 145 clusters, coverage was 31.1% (95% confidence intervals [CI]: 24.1–38.0%). Most respondents were not offered medicines. To improve coverage in the second round, three LGAs were randomized to receive MDA through a “modified campaign” approach focused on improved supervision and monitoring. The other two LGAs continued with standard MDA as before. A similar survey was conducted after the second round, interviewing 3,362 people in 87 clusters across the five LGAs. Coverage was not statistically different from the first round (40.0% [95% CI: 31.0–49.0%]) and there was no significant difference between the groups (P = 0.7), although the standard MDA group showed improvement over round 1 (P < 0.01). The additional cost per treatment in the modified MDA was 1.6 times that of standard MDA. Compliance was excellent among those offered treatment. We concluded that poor mobilization, medicine distribution, and program penetration led to low coverage. These must be addressed to improve treatment coverage in Edo state. more...

Ivermectin treatment can cause central nervous system adverse events (CNS-AEs) in persons with very high-density Loa loa microfilaremia (≥ 30,000 mf/mL blood). Hypoendemic onchocerciasis areas where L. loa is endemic have been excluded from ivermectin mass drug administration programs (MDA) because of the concern for CNS AEs. The rapid assessment procedure for L. loa (RAPLOA) is a questionnaire survey to assess history of eye worm. If ≥ 40% of respondents report eye worm, this correlates with ≥ 2% prevalence of very high-density loiasis microfilaremia, posing an unacceptable risk of CNS-AEs after MDA. In 2016, we conducted a L. loa study in 110 ivermectin-naive, suspected onchocerciasis hypoendemic villages in southern Nigeria. In previous RAPLOA surveys these villages had prevalences between 10% and 67%. We examined 10,605 residents using the LoaScope, a cell phone-based imaging device for rapidly determining the microfilaria (mf) density of L. loa infections. The mean L. loa village mf prevalence was 6.3% (range 0-29%) and the mean individual mf count among positives was 326 mf/mL. The maximum individual mf count was only 11,429 mf/mL, and among 2,748 persons sampled from the 28 villages with ≥ 40% RAPLOA, the ≥ 2% threshold of very high Loa mf density could be excluded with high statistical confidence (P < 0.01). These findings indicate that ivermectin MDA can be delivered in this area with extremely low risk of L. loa-related CNS-AEs. We also concluded that in Nigeria the RAPLOA survey methodology is not predictive of ≥ 2% prevalence of very high-density L. loa microfilaremia. more...

Nigeria has the largest population at risk for lymphatic filariasis (LF) in Africa. This study used a transmission assessment survey (TAS) to determine whether mass drug administration (MDA) for LF could stop in 21 districts, divided into four evaluation units (EUs), of Plateau and Nasarawa States, Nigeria, after 8–12 years of annual albendazole–ivermectin treatment. A total of 7,131 first- and second-year primary school children (approximately 6–7 years old) were tested for LF antigen by immunochromatographic test (ICT) from May to June 2012. The target sample size of 1,692 was exceeded in each EU (range = 1,767–1,795). A total of 25 (0.4%) individuals were ICT positive, with the number of positives in each EU (range = 3–11) less than the TAS cutoff of 20, meaning that LF transmission had been reduced below sustainable levels. As a result, 3.5 million annual albendazole–ivermectin treatments were halted in 2013. Combined with the previous halt of MDA for LF in other parts of Plateau and Nasarawa, these are the first Nigerian states to stop LF MDA statewide. Posttreatment surveillance is ongoing to determine if LF transmission has been interrupted. more...

Although there is increasing importance placed on the use of mathematical models for the effective design and management of long-term parasite elimination, it is becoming clear that transmission models are most useful when they reflect the processes pertaining to local infection dynamics as opposed to generalized dynamics. Such localized models must also be developed even when the data required for characterizing local transmission processes are limited or incomplete, as is often the case for neglected tropical diseases, including the disease system studied in this work, viz. lymphatic filariasis (LF). Here, we draw on progress made in the field of computational knowledge discovery to present a reconstructive simulation framework that addresses these challenges by facilitating the discovery of both data and models concurrently in areas where we have insufficient observational data. Using available data from eight sites from Nigeria and elsewhere, we demonstrate that our data-model discovery system is able to estimate local transmission models and missing pre-control infection information using generalized knowledge of filarial transmission dynamics, monitoring survey data, and details of historical interventions. Forecasts of the impacts of interventions carried out in each site made by the models estimated using the reconstructed baseline data matched temporal infection observations and provided useful information regarding when transmission interruption is likely to have occurred. Assessments of elimination and resurgence probabilities based on the models also suggest a protective effect of vector control against the reemergence of LF transmission after stopping drug treatments. The reconstructive computational framework for model and data discovery developed here highlights how coupling models with available data can generate new knowledge about complex, data-limited systems, and support the effective management of disease programs in the face of critical data gaps., Author summary As modelling becomes commonly used in the design and evaluation of parasite elimination programs, the need for well-defined models and datasets describing the nature of transmission processes in local settings is becoming pronounced. For many neglected tropical diseases, however, data for site-specific model identification are typically sparse or incomplete. In this study, we present a new data-model computational discovery system that couples data-assimilation methods based on existing monitoring survey data with model-generated data about baseline conditions to discover the local transmission models required for simulating the impacts of interventions in typical endemic locations for the macroparasitic disease, lymphatic filariasis (LF). Using data from eight study sites in Nigeria and elsewhere, we show that our reconstructive computational framework is able to combine information contained within partially-available site-specific monitoring data with knowledge of parasite transmission dynamics embedded in process-based models to generate the missing data required for inducing reliable locally applicable LF models. We also show that the models so discovered are able to generate the intervention forecasts required for supporting management-relevant decisions in parasite elimination. more...

A recent article “Is onchocerciasis elimination in Africa feasible by 2025: a perspective based on lessons learnt from the African control programmes” in Infectious Diseases of Poverty claimed that undue influence on African programs by concepts developed by the Onchocerciasis Elimination Program of the Americas (OEPA) is detrimental to stopping mass drug administration (MDA) in Africa. This claim is made despite a record year for MDA stoppage in four African countries of > 3.5 million treatments in 2018, far exceeding any past OEPA or African Program for Onchocerciasis Control (APOC) stop MDA success. Electronic supplementary material The online version of this article (10.1186/s40249-019-0558-0) contains supplementary material, which is available to authorized users. more...

Stopping interventions is a critical decision for parasite elimination programmes. Quantifying the probability that elimination has occurred due to interventions can be facilitated by combining infection status information from parasitological surveys with extinction thresholds predicted by parasite transmission models. Here we demonstrate how the integrated use of these two pieces of information derived from infection monitoring data can be used to develop an analytic framework for guiding the making of defensible decisions to stop interventions. We present a computational tool to perform these probability calculations and demonstrate its practical utility for supporting intervention cessation decisions by applying the framework to infection data from programmes aiming to eliminate onchocerciasis and lymphatic filariasis in Uganda and Nigeria, respectively. We highlight a possible method for validating the results in the field, and discuss further refinements and extensions required to deploy this predictive tool for guiding decision making by programme managers., The decision when to stop an intervention is a critical component of parasite elimination programmes, but reliance on surveillance data alone can be inaccurate. Here, Michael et al. combine parasite transmission model predictions with disease survey data to more reliably determine when interventions can be stopped. more...

Ivermectin treatment can cause central nervous system adverse events (CNS-AEs) in persons with very high-density Loa loa microfilaremia (≥ 30,000 mf/mL blood). Hypoendemic onchocerciasis areas where L. loa is endemic have been excluded from ivermectin mass drug administration programs (MDA) because of the concern for CNS AEs. The rapid assessment procedure for L. loa (RAPLOA) is a questionnaire survey to assess history of eye worm. If ≥ 40% of respondents report eye worm, this correlates with ≥ 2% prevalence of very high-density loiasis microfilaremia, posing an unacceptable risk of CNS-AEs after MDA. In 2016, we conducted a L. loa study in 110 ivermectin-naïve, suspected onchocerciasis hypoendemic villages in southern Nigeria. In previous RAPLOA surveys these villages had prevalences between 10% and 67%. We examined 10,605 residents using the LoaScope, a cell phone–based imaging device for rapidly determining the microfilaria (mf) density of L. loa infections. The mean L. loa village mf prevalence was 6.3% (range 0–29%) and the mean individual mf count among positives was 326 mf/mL. The maximum individual mf count was only 11,429 mf/mL, and among 2,748 persons sampled from the 28 villages with ≥ 40% RAPLOA, the ≥ 2% threshold of very high Loa mf density could be excluded with high statistical confidence (P < 0.01). These findings indicate that ivermectin MDA can be delivered in this area with extremely low risk of L. loa–related CNS-AEs. We also concluded that in Nigeria the RAPLOA survey methodology is not predictive of ≥ 2% prevalence of very high-density L. loa microfilaremia. more...

Introduction We investigated the impact of two round of mass drug administration on trachoma prevalence in Plateau and Nasarawa States of Nigeria. The mass drug administration was conducted as a component of the SAFE Strategy, a combination of interventions recommended for the global elimination of blinding trachoma. Methods The study consisted of a two-stage cross-sectional clustered sample survey in which 3990 people from 793 households were screened for clinical signs of trachoma. Results Of the total 3990 people examined, 1530 were children, of which 808 (53%) were boys and 704 (47%) were girls. The impact of intervention as measured by the changes in overall prevalence of follicular trachoma were as follows: At baseline the overall prevalence of follicular trachoma among children 1–9 years of age was 6.4%, 95% CI [5.8, 7.0]; the overall prevalence of trachomatous trichiasis in the total population was 0.20%, 95% CI [0.16, 0.25]. At follow up, the overall prevalence of follicular trachoma among children 1–9 years of age was 3.4%, 95% CI [1.9, 4.9]; the overall prevalence of trachomatous trichiasis in the total population was 0.20%, 95% CI [0.00, 0.05]. The highest statistically significant reduction (96%) in follicular trachoma prevalence was observed in Doma Local Government Area of Nasarawa State from baseline prevalence of 13.6%, 95% CI [9.7, 17.5] to follow-up prevalence of 0.5%, 95% CI [0.0, 1.5] and the lowest reduction (58%) in follicular trachoma prevalence was observed in Langtang North Local Government Area of Plateau State from baseline prevalence of 15.8%, 95% CI [9.3, 22.3] to 6.6%, 95% CI [1.6, 11.6], (p more...

National onchocerciasis elimination committees (NOECs) serve to help ministries of health complete the pathway to successful verification of elimination of onchocerciasis (river blindness), as outlined in the 2016 World Health Organization guidelines. These guidelines, however, only take effect when the country believes it has reached a point that elimination can be demonstrated, and do not address the preceding milestones. Therefore, NOECs can be of great help with guiding and tailoring earlier planning, programming and assessments to empower national programs to aggressively move toward their countries' elimination goals. In this article, we provide suggestions for organizing NOECs and examples of four such committees that have successfully operated in Africa and the Americas. more...

Objectives: The World Health Organization has called upon member states to eliminate blinding trachoma by 2020 using the SAFE strategy. We aimed to determine the prevalence of trachoma and quantify intervention needs for each aspect of the SAFE (surgery, mass administration of antibiotics, promotion of facial cleanliness and environmental improvements) strategy in Nasarawa and Plateau States, Nigeria. Methods: District-based, household cluster surveys were conducted in all 30 local government areas (LGAs) within the states. Results: A total of 46 960 persons were examined from 7883 selected households. Prevalence estimates of trachomatous inflammation follicular among children 1–9 years of age ranged from 1.7 to 15.8% by LGA. Trichiasis prevalence among adults varied by LGA from 0 to 2.1% and was more common among women (OR = 1.99, 95% CI 1.3 to 3.1). Access to water within a 30 min round trip was reported by 82.3% of households. Conclusion: LGA-wide trachoma control interventions are warranted in seven LGAs targeting: 5409 persons for surgery to correct trichiasis, 778 698 persons to receive at least three rounds of mass antibiotic distribution, 855 villages in which to promote face-washing and sanitation, and 102 751 households for latrine construction. These mapping surveys demonstrate an example of evidence-based programme planning necessary for measuring progress towards achieving the GET 2020 objective and can be replicated in other areas yet to be mapped for trachoma. more...

We determined whether the school-based "disease mapping" methodology used to assess urinary schistosomiasis (SCH) is useful for determining trachoma interventions and whether the district-based approach recommended for trachoma is useful for SCH control programs. We conducted two separate integrated surveys in eight districts of central Nigeria: school based and district based. A total of 17,189 children were examined for trachoma and 16,238 children were examined for hematuria from 363 schools and 2,149 households. School surveys identified 67 communities warranting praziquantel drug treatment of SCH and 142 trachoma-endemic communities warranting trachoma control activities. In district-level estimates, we identified 24 communities for praziquantel treatment and 0 for trachoma intervention. Integrating trachoma into SCH school-based surveys, and SCH into trachoma surveys, was quick and easy, but in this setting, school-based surveys were more useful for identifying communities where intervention is warranted. more...

Africa's populous country, Nigeria, contains or contained more cases of dracunculiasis, onchocerciasis, lymphatic filariasis, and schistosomiasis than any other African nation and ranks or ranked first (dracunculiasis, onchocerciasis, schistosomiasis) or third (lymphatic filariasis) in the world for the same diseases. After beginning village-based interventions against dracunculiasis 20 years ago and confronting onchocerciasis a few years later, Nigeria has nearly eliminated dracunculiasis and has provided annual mass drug administration for onchocerciasis to over three quarters of that at-risk population for 7 years. With assistance from The Carter Center, Nigeria began treating lymphatic filariasis and schistosomiasis in two and three states, respectively, over the past decade, while conducting pioneering operational research as a basis for scaling up interventions against those diseases, for which much more remains to be done. This paper describes the status of Nigeria's struggles against these four neglected tropical diseases and discusses challenges and plans for the future. more...

In a pilot program of mass surgery weeks (MSW) to provide hydrocelectomy services to men with filarial scrotal hydrocele, local general practitioners performed 425 surgical repairs in 301 men in five MSW in three rural Nigerian community hospitals between 2002 and 2005. The most common (94%) procedure used was the eversion technique, which was most familiar to the practitioners. Postoperative complications included hematoma (3.7%) and infection (3%), and there was one death from infection in an elderly man with previously unrecognized diabetes. In 115 patients (38%) followed for 1 to 3 years, the hydrocele recurrence rate was 7%. The eversion technique gives an acceptable outcome, and MSW are safe and effective if strict attention is paid to preoperative screening of candidates and asepsis. more...

Both Schistosoma haematobium and S. mansoni are endemic in Nigeria. Since 1999 the ministries of health of Plateau and Nasarawa states, assisted by The Carter Center, have provided mass drug administrations with praziquantel to villages where >20% of the school-aged children tested with urine dipsticks have been found to have haematuria (presumed to be caused by S. haematobium). The current extent of S. mansoni in Nigeria remains relatively unknown because the tests needed to detect human infection with this parasite are difficult to perform in many endemic areas. In a cross-sectional survey involving 924 children, the prevalence of S. mansoni was determined in 30 villages (in four local government areas) that had been excluded from mass praziquantel administrations because the prevalence of haematuria in their school-aged children had been found to be more...

To assess the prevalence of trachomatous inflammation follicular (TF) in children aged 1-9 years and trachomatous trichiasis (TT) in adults aged 15 years or more in Katsina State, Nigeria.Cross sectional population-based trachoma prevalence surveys were conducted using multistage cluster random sampling methodology and the WHO simplified grading system for trachoma in ten local government areas (LGAs). Individual and household risk factors were recorded using a standard questionnaire.A total of 11,407 children and 8,901 adults from 2,244 households were surveyed. Prevalence of TF in children aged 1-9 years ranged from 5.0 to 24.0%. Five LGAs exceeded the 10% threshold for intervention and a further three exceeded 10% in the 95% confidence limits. The prevalence of TT in adults aged 15 years or more ranged from 2.3 to 8.0%: all ten LGAs exceeded the 1% intervention threshold. Analysis of risk factors for active trachoma (TF and/or TI) in children showed the following significant independent associations: Presence of ocular discharge OR = 2.34 (95%CI 1.81-3.03); presence of nasal discharge OR = 1.44 (1.22-1.70); reported frequency of face washing once versus at least twice per day OR = 1.27 (1.02-1.58); disposal of trash inside the compound OR = 1.23 (1.02-1.48); and the absence of a household latrine OR = 1.43 (1.15-1.78).A trachoma control program is warranted in Katsina. Surgical interventions to correct TT are needed immediately in all LGAs surveyed and the full SAFE strategy is justified for five of the ten LGAs, and possibly for another three. more...

Millions of long-lasting insecticide treated nets (LLINs) have been distributed as part of the global malaria control strategy. LLIN ownership, however, does not necessarily guarantee use. Thus, even in the ideal setting in which universal coverage with LLINs has been achieved, maximal malaria protection will only be achieved if LLINs are used both correctly and consistently. This study investigated the factors associated with net use, independent of net ownership. Data were collected during a household survey conducted in Ebonyi State in southeastern Nigeria in November 2011 following a statewide mass LLIN distribution campaign and, in select locations, a community-based social behavior change (SBC) intervention. Logistic regression analyses, controlling for household bed net ownership, were conducted to examine the association between individual net use and various demographic, environmental, behavioral and social factors. The odds of net use increased among individuals who were exposed to tailored SBC in the context of a home visit (OR = 17.11; 95% CI 4.45–65.79) or who received greater degrees of social support from friends and family (ptrend < 0.001). Factors associated with decreased odds of net use included: increasing education level (ptrend = 0.020), increasing malaria knowledge level (ptrend = 0.022), and reporting any disadvantage of bed nets (OR = 0.39; 95% CI 0.23–0.78). The findings suggest that LLIN use is significantly influenced by social support and exposure to a malaria-related SBC home visit. The malaria community should thus further consider the importance of community outreach, interpersonal communication and social support on adoption of net use behaviors when designing future research and interventions. more...

In Africa anopheline mosquitoes transmit malaria and lymphatic filariasis (LF); insecticide-treated bed nets significantly reduce transmission of both. Insecticide-treated bed net provision to children under 5 (U5) and pregnant women (PW) is a major goal of malaria control initiatives, but use in Africa remains low because of cost and logistics. We therefore integrated insecticide-treated bed net distribution with the 2004 LF/onchocerciasis mass drug administration (MDA) program in Central Nigeria. Community volunteers distributed 38,600 insecticide-treated bed nets, while simultaneously treating 150,800 persons with ivermectin/albendazole (compared with 135,600 in 2003). This was subsequently assessed with a 30-cluster survey. Among surveyed households containing U5/PW, 80% (95% CI, 72-87%) owned > or = 1 insecticide-treated bed net, a 9-fold increase from 2003. This first linkage of insecticide-treated bed net distribution with mass drug administration resulted in substantial improvement in insecticide-treated bed net ownership and usage, without adversely affecting mass drug administration coverage. Such integration allowed two programs to share resources while realizing mutual benefit, and is one model for rapidly improving insecticide-treated bed net coverage objectives. more...

A prospective entomological survey was conducted in four sentinel villages in central Nigeria from 1999-2002, to assess the impact of annual, single-dose, mass drug administrations (MDA), with a combination of ivermectin and albendazole, on the transmission of Wuchereria bancrofti. As they were also endemic for human onchocerciasis, the four villages had received annual MDA based on ivermectin alone for 7 years prior to the addition of albendazole. Resting Anophelines gambiae s. l., An. funestus and Culex species were collected from 92 sequentially sampled households and dissected. Mosquitoes harbouring any larval stage of W. bancrofti were classified as 'infected', and those containing the third-stage larvae of the parasite were classified as 'infective'. Over the 41-month observation period, 4407 mosquitoes were captured and dissected, of which 64% were An. gambiae s. l., 34% An. funestus, and 1% Culex species. The baseline data, from dissections performed before the addition of albendazole to the MDA, showed high prevalences of mosquito infection (8.9%) and infectivity (2.9%), despite apparently good treatment coverages during the years of annual ivermectin monotherapy. Only the anopheline mosquitoes were found to harbour W. bancrofti larvae. After the third round of MDA with the ivermectin-albendazole combination, statistically significant decreases in the prevalences of mosquito infection (down to 0.6%) and infectivity (down to 0.4%) were observed (P0.0001 for each). The combination of albendazole and ivermectin appears to be superior to ivermectin alone for reducing the frequency of W. bancrofti infection in mosquitoes. more...

During annual rounds of mass treatment against onchocerciasis, women who are pregnant or nursing neonates should not to be offered ivermectin. The aim of the present study was to determine how many women were not treated, as a result of this policy, in four villages in south-eastern Nigeria. Of the 1714 women of reproductive age present during the 2000 round of mass treatment, 599 (35%) were excluded because they were pregnant or nursing babies aged < 1 month. Most (56%) of the 599 excluded women were, however, treated individually later in the year. Of the 264 excluded women who did not receive a dose of ivermectin at all in 2000, 123 (47%) said they would have actively sought ivermectin treatment had they been made aware of the short duration of exclusion for nursing. If they had all known of the short duration of the exclusion and when and how to locate and receive treatment in their villages after the round of mass treatment, 91% of the women excluded from the round of mass treatment would probably have been treated later in the year. Better treatment systems, follow-up and health education, targeted at pregnant and lactating women, would improve treatment coverage of this group after parturition and early nursing. more...

We conducted a cohort study on impact of effects of eight years of annual ivermectin mass treatment administered in eight villages in Imo State, Nigeria. Physical and visual acuity examinations carried out in 462 persons in 1995, prior to the launching of mass drug administration with ivermectin, were compared with re-examinations of 411 (89%) of these same individuals in 2002. We found that gross visual impairment decreased from 16% to 1%, nodule prevalence decreased from 59% to 18%, and papular dermatitis was reduced from 15% to 2%. No change was seen in leopard skin rates (14%). The only incident lesions were three subjects from a single community having the appearance of new nodules (e.g., nodules not identified in the 1995 examinations). Differences in community coverage did not appear to influence the benefit from treatment of individual residents. more...

Background This study was undertaken in five onchocerciasis/lymphatic filariasis (LF) co-endemic local government areas (LGAs) in Plateau and Nasarawa, Nigeria. Annual MDA with ivermectin had been given for 17 years, 8 of which were in combination with albendazole. In 2008, assessments indicated that LF transmission was interrupted, but that the MDA had to continue due to the uncertain status of onchocerciasis transmission. Accordingly, assessments to determine if ivermectin MDA for onchocerciasis could be stopped were conducted in 2009. Methods We evaluated nodule, microfilarial (mf) skin snip, and antibody (IgG4 response to OV16) prevalence in adults and children in six sentinel sites where baseline data from the 1990s were available. We applied the 2001 WHO criteria for elimination of onchocerciasis that defined transmission interruption as an infection rate of, Author Summary Both lymphatic filariasis and onchocerciasis are treated with ivermectin-based mass drug administration (MDA) regimens in Africa. Where the infections are co-endemic, ivermectin treatments cannot be stopped until both infection transmission cycles are broken. This report follows a previous determination that the LF transmission cycle had been interrupted in five districts (LGAs in Nigeria) but evidence was needed on the status of the onchocerciasis transmission cycle prior to halting MDA. In this report we determined (based on WHO guidelines) that most likely the transmission of onchocerciasis has been interrupted in Plateau and Nasarawa States and we conclude that ivermectin MDA could be stopped. more...

(2008). Triple drug administration (TDA), with praziquantel, ivermectin and albendazole, for the prevention of three neglected tropical diseases in Nigeria. Annals of Tropical Medicine & Parasitology: Vol. 102, No. 2, pp. 177-179. more...

The onchocerciasis control programme in Plateau state (now Plateau and Nasarawa states), Nigeria, was one of the pioneering Mectizan-distribution projects in Nigeria. Although initiated under the River Blindness Foundation (RBF) in 1991, in collaboration with the Ministry of Health, it was absorbed into the Carter Center's Global 2000 River Blindness Programme (GRBP) in 1996. The objectives of the programme were to support the delivery of Mectizan (ivermectin, MSD) to at least 80% of those living in communities where onchocerciasis was highly endemic, within the first 3 years of the project's inception, and to maintain this coverage for a period of 10-15 years. The programme has so far been successful, and much of this success is attributed to problem identification and problem-solving through continuous review and evaluation of programme activities, and implementation of strategies, when required, to ensure those programme objectives are met. The implementation steps of the programme, and some of the managerial problems identified during the course of the effort, are reviewed. The challenge now is to learn how to transform this functional, programme-designed and programme-directed effort into the new community-directed treatment being promoted by the African Programme for Onchocerciasis Control. The new challenges of the transition require middle-level managers and implementors with effective, efficient and indeed state-of-the-art management skills. more...

Background: Nigeria suffers the world’s largest malaria burden, with approximately 51 million cases and 207,000 deaths annually. As part of the country’s aim to reduce by 50% malaria-related morbidity and mortality by 2013, it embarked on mass distribution of free long-lasting insecticidal nets (LLINs). Methods: Prior to net distribution campaigns in Abia and Plateau States, Nigeria, a modified malaria indicator survey was conducted in September 2010 to determine baseline state-level estimates of Plasmodium prevalence, childhood anemia, indoor residual spraying (IRS) coverage and bednet ownership and utilization. Results: Overall age-adjusted prevalence of Plasmodium infection by microscopy was similar between Abia (36.1%, 95% CI: 32.3%–40.1%; n = 2,936) and Plateau (36.6%, 95% CI: 31.3%–42.3%; n = 4,209), with prevalence highest among children 5-9 years. P. malariae accounted for 32.0% of infections in Abia, but only 1.4% of infections in Plateau. More than half of children ≤10 years were anemic, with anemia significantly higher in Abia (76.9%, 95% CI: 72.1%–81.0%) versus Plateau (57.1%, 95% CI: 50.6%–63.4%). Less than 1% of households in Abia (n = 1,305) or Plateau (n = 1,335) received IRS in the 12 months prior to survey. Household ownership of at least one bednet of any type was 10.1% (95% CI: 7.5%–13.4%) in Abia and 35.1% (95% CI: 29.2%-41.5%) in Plateau. Ownership of two or more bednets was 2.1% (95% CI: 1.2%–3.7%) in Abia and 14.5% (95% CI: 10.2%–20.3%) in Plateau. Overall reported net use the night before the survey among all individuals, children more...

Lymphatic filariasis (LF) in rural southeastern Nigeria is transmitted mainly by Anopheles spp. mosquitoes. Potential coinfection with Loa loa in this area has prevented use of ivermectin in the mass drug administration (MDA) strategy for LF elimination because of potential severe adverse L. loa-related reactions. This study determined if long-lasting insecticidal net (LLIN) distribution programs for malaria would interrupt LF transmission in such areas, without need for MDA. Monthly entomologic monitoring was conducted in sentinel villages before and after LLIN distribution to all households and all age groups (full coverage) in two districts, and to pregnant women and children less than five years of age in the other two districts. No change in human LF microfilaremia prevalence was observed, but mosquito studies showed a statistically significant decrease in LF infection and infectivity with full-coverage LLIN distribution. We conclude that LF transmission can be halted in southeastern Nigeria by full-coverage LLIN distribution, without MDA. more...

The use of community residents as agents for distributing mass ivermectin therapy for onchocerciasis provides a component of community participation absent from mobile team delivery methods. Community-based distribution, however, presupposes preexisting human resources in the endemic villages capable of fulfilling the essential functions of an ivermectin distribution process: mobilizing and educating the population, dispensing the drug, maintaining records, and monitoring and treating adverse reactions. Even when such human resources exist, the community workers must continue to receive tangible support from both external (government and donor agencies) and internal (community) sources. Donor and government agencies must accept that their data collection demands will be limited by the literacy standards of the communities being served. Community leaders must agree to set and use their own local standards of payment (including food stuffs or exchange in kind) to compensate the distributors for their time and efforts. The use of locally available human and remunerative resources is a prerequisite for true community ownership of a program. more...

Onchocerciasis, lymphatic filariasis (LF), schistosomiasis and soil transmitted, helminthiasis (STH) are all co-endemic in Nigeria. Annual mass drug administration (MDA) with ivermectin (for onchocerciasis), albendazole (for STH and with ivermectin for LF) and praziquantel (for schistosomiasis) is the WHO-recommended treatment strategy for preventive chemotherapy. Separate delivery rounds for distribution of these drugs have been the usual approach to MDA. All three drugs, however, have now been shown to be clinically and programmatically safe for co-administration with what has come to be known as triple drug administration (TDA). We examined the cost savings of converting from separate delivery rounds to TDA in two states in Nigeria. In 2008, eight local government areas received a single round of ivermectin with albendazole followed at least 1 week later by a single round of praziquantel to school-aged children. The following year, a single round was administered with TDA. The number of treated individuals was essentially unchanged during both years (1 301 864 in 2008 and 1 297 509 in 2009) and no change in adverse events was reported. The total programmatic costs for the MDA, not including drug and overhead costs, reduced by 41% from $123, 624 to $72, 870. Cost savings were limited in larger populations due to economies of scale. TDA is recommended for mature MDA. more...

Nigeria is highly endemic for infection with Schistosoma haematobium, which most commonly manifests itself with blood in urine. To monitor the impact of annual mass drug administration (MDA) with Praziquantel for S. haematobium in Delta State, Nigeria, cross-sectional hematuria surveys of school children were conducted in 8 sentinel villages (SVs) at baseline (n=240) and after two annual doses (n=402). We assessed the comparability of three assessments of hematuria (child's reported history, nurse visual diagnosis (NVD) and dipstick) to determine the need for mass treatment. Dipstick was considered to be the gold standard. Prior to treatment, history and NVD each identified only the 3 most highly prevalent SVs, and overall this represented just 37.5% of the 8 SVs in need of treatment. Following treatment, after dipstick prevalence decreased by 88.5% (p more...

We evaluated the effect of annual ivermectin (IV) distribution for onchocerciasis on the prevalence of soil transmitted helminth (STH) infections in school-aged (SAC) and preschool-aged (PAC) children by comparing children in villages that had received treatment for 13 years to those from socioeconomically similar villages in untreated areas. We enrolled 1,031 SAC and 211 PAC for Kato Katz examinations. Treated areas had a lower prevalence of Ascaris (SAC: 3% versus 12%, P < 0.0001; PAC: 3% versus 10%, P < 0.051) and Trichuris (SAC: 6% versus 10%, P = 0.012; PAC: 1% versus 8%, P = 0.019), but not hookworm (SAC: 38% versus 42%, P = 0.20; PAC: 21% versus 27%, P = 0.30). The prevalence of Ascaris or Trichuris in treated areas was below the WHO threshold for mass antihelminthic treatment (MDA), but not for hookworm. We conclude that benzimidazole MDA in IV treatment areas is indicated to effectively control hookworm. more...

This report describes how Nigeria, a country that at one time had the highest number of cases of dracunculiasis (Guinea worm disease) in the world, reduced the number of cases from more than 653,000 in 1988 to zero in 2009, despite numerous challenges. Village-based volunteers formed the foundation of the program, which used health education, cloth filters, vector control, advocacy for safe water, voluntary isolation of patients, and monitored program interventions and cases reported monthly. Other factors in the program's success were strong governmental support, advocacy by a former head of state of Nigeria, technical and financial assistance by The Carter Center, the U.S. Centers for Disease Control and Prevention, the United Nations Children's Fund, the World Health Organization, and many other partners and donors. The estimated cost of the Nigerian program during 1988-2009 is $37.5 million, not including funding for water supply projects or salaries of Nigerian governmental workers. more...

The results of previous studies in Nigeria indicate that 81% of the villages in Plateau and Nasarawa states probably qualify for the mass administration of praziquantel (PZQ) because of Schistosoma haematobium (SH) and/or S. mansoni (SM) infection. To determine the best strategy, relative costs were modelled for four different programmatic approaches to mass drug administration (MDA) at village level. The approaches considered were (1) village-by-village screening for SH (using dipsticks to test for haematuria), with MDA confined to those villages where at least 20% of school-aged children were found infected; (2) screening for both SM (using Kato-Katz smears) and SH, with MDA confined to those villages where at least 20% of school-aged children were found infected with SH or at least 10% of such children were found SM-positive; (3) the presumptive annual treatment of all school-aged children with PZQ (without village-by-village screening); and (4) the presumptive annual treatment of all eligible adults and children with PZQ. In the MDA in models 1 and 2, treatment is only given to children unless the prevalence of schistosome infection isor=50%, when adults are also treated. As first-year 'assessment' costs were particularly high for the models that included screening, costs were projected over 5 years for all four models. The total 5-year costs, to cover a population of 30,000, were U.S.$18,673 for the model with screening only for SH, U.S.$36,816 for the model with screening for both SH and SM, U.S. $15,510 for the treatment of all school-aged children, and U.S.$68,610 for the treatment of the entire population. Although the presumptive treatment of school-aged children appeared to be the cheapest approach, it would exclude the community-wide treatment of highly endemic communities, the importance of which needs further study. more...

Africa's populous country, Nigeria, contains or contained more cases of dracunculiasis, onchocerciasis, lymphatic filariasis, and schistosomiasis than any other African nation and ranks or ranked first (dracunculiasis, onchocerciasis, schistosomiasis) or third (lymphatic filariasis) in the world for the same diseases. After beginning village-based interventions against dracunculiasis 20 years ago and confronting onchocerciasis a few years later, Nigeria has nearly eliminated dracunculiasis and has provided annual mass drug administration for onchocerciasis to over three quarters of that at-risk population for 7 years. With assistance from The Carter Center, Nigeria began treating lymphatic filariasis and schistosomiasis in two and three states, respectively, over the past decade, while conducting pioneering operational research as a basis for scaling up interventions against those diseases, for which much more remains to be done. This paper describes the status of Nigeria's struggles against these four neglected tropical diseases and discusses challenges and plans for the future. more...

In a pilot program of mass surgery weeks (MSW) to provide hydrocelectomy services to men with filarial scrotal hydrocele, local general practitioners performed 425 surgical repairs in 301 men in five MSW in three rural Nigerian community hospitals between 2002 and 2005. The most common (94%) procedure used was the eversion technique, which was most familiar to the practitioners. Postoperative complications included hematoma (3.7%) and infection (3%), and there was one death from infection in an elderly man with previously unrecognized diabetes. In 115 patients (38%) followed for 1 to 3 years, the hydrocele recurrence rate was 7%. The eversion technique gives an acceptable outcome, and MSW are safe and effective if strict attention is paid to preoperative screening of candidates and asepsis. more...

In areas of Nigeria where onchocerciasis is endemic, community-directed distributors (CDD) distribute ivermectin annually, as part of the effort to control the disease. Unfortunately, it has been reported that at least 35% of the distributors who have been trained in Nigeria are unwilling to participate further as CDD. The selection and training of new CDD, to replace those unwilling to continue, leads to annual expense that the national onchocerciasis-programme is finding difficult to meet, given other programme priorities and the limited resources. If the reported levels of attrition are true, they seriously threaten the sustainability of community-directed treatment with ivermectin (CDTI) in Nigeria. In 2002, interviews were held with 101 people who had been trained as CDD, including those who had stopped serving their communities, from 12 communities in south-eastern Nigeria that had high rates of CDD attrition. The results showed that, although the overall reported CDD attrition was 40.6%, the actual rate was only 10.9%. The CDD who had ceased participating in the annual rounds of ivermectin blamed a lack of incentives (65.9%), the demands of other employment (14.6%), the long distances involved in the house-to-house distribution (12.2%) or marital duties (7.3%). Analysis of the data obtained from all the interviewed CDD showed that inadequate supplies of ivermectin (P0.01), lack of supervision (P0.05) and a lack of monetary incentives (P0.001) led to significant increases in attrition. Conversely, CDD retention was significantly enhanced when the distributors were selected by their community members (P0.001), supervised (P0.001), supplied with adequate ivermectin tablets (P0.05), involved in educating their community members (P0.05), and/or involved in other health programmes (P0.001). Although CDD who were involved in other health programmes were relatively unlikely to cease participating in the distributions, they were more likely to take longer than 14 days to complete ivermectin distribution than other CDD, who only distributed ivermectin. Data obtained in interviews with present and past CDD appear vital for informing, directing, protecting and enhancing the performance of CDTI programmes, in Nigeria and elsewhere. more...

Wuchereria bancrofti and the other mosquito-borne parasites that cause human lymphatic filariasis (LF) infect over 120 million people world-wide. Global efforts are underway to stop transmission of the parasites, using annual, single-dose mass drug administrations (MDA) to all at-risk populations. Although most MDA to date have been in rural settings, they are also recommended in urban areas of transmission. It remains unclear whether there is significant urban transmission in West Africa, however, and the need for urban MDA in this region therefore remains a matter of debate.Clinic-based surveillance, for the clinical manifestations of LF, has now been used to identify areas of urban transmission of W. bancrofti in Jos, the major urban population centre of Plateau state, Nigeria. The eight clinics investigated were all located in slum areas, close to vector breeding sites, and were therefore considered to serve at-risk populations. Over a 1-month period, selected providers in these clinics sought hydrocele, lymphoedema, elephantiasis, or acute adenolymphangitis among the patients seeking treatment. The consenting patients who were suspected clinical cases of LF, and a cohort of patients suspected to be cases of onchocerciasis, were tested for W. bancrofti antigenaemia. All the patients were asked a series of questions in an attempt to determine if those found antigenaemic could only have been infected in an urban area. During the study, 30 suspected clinical cases of LF were detected and 18 of these (including two patients who were found to be antigenaemic) lived in urban areas. Of the 98 patients with exclusively urban exposure who were tested for filarial antigenaemia, six (6.1%) were found antigenaemic. Clinic-based surveillance appears to be a useful tool for determining if there is W. bancrofti transmission in an urban setting. more...

PROBLEM: Annual mass drug administration (MDA) with safe oral anthelminthic drugs (praziquantel, ivermectin and albendazole) is the strategy for control of onchocerciasis, lymphatic filariasis (LF) and schistosomiasis. District health officers seek to integrate treatment activities in areas of overlapping disease endemicity, but they are faced with having to merge different programmatic guidelines. APPROACH: We proceeded through the three stages of integrated MDA implementation: mapping the distribution of the three diseases at district level; tailoring district training and logistics based on the results of the mapping exercises; and implementing community-based annual health education and mass treatment where appropriate. During the process we identified the "know-do" gaps in the MDA guidelines for each disease that prevented successful integration of these programmes. LOCAL SETTING: An integrated programme launched in 1999 in Plateau and Nasarawa States in central Nigeria, where all three diseases were known to occur. RELEVANT CHANGES: Current guidelines allowed onchocerciasis and LF activities to be integrated, resulting in rapid mapping throughout the two states, and states-wide provision of over 9.3 million combined ivermectin-albendazole treatments for the two diseases between 2000 and 2004. In contrast, schistosomiasis activities could not be effectively integrated because of the more restrictive guidelines, resulting in less than half of the two states being mapped, and delivery of only 701 419 praziquantel treatments for schistosomiasis since 1999. LESSONS LEARNED: Integration of schistosomiasis into other MDA programmes would be helped by amended guidelines leading to simpler mapping, more liberal use of praziquantel and the ability to administer praziquantel simultaneously with ivermectin and albendazole. more...

There has long been interest in determining if mass ivermectin administration for onchocerciasis has 'unknowingly' interrupted lymphatic filariasis (LF) transmission where the endemicity of the two diseases' overlaps. We studied 11 communities in central Nigeria entomologically for LF by performing mosquito dissections on Anopheline LF vectors. Six of the communities studied were located within an onchocerciasis treatment zone, and five were located outside of that zone. Communities inside the treatment zone had been offered ivermectin treatment for two-five years, with a mean coverage of 81% of the eligible population (range 58–95%). We found 4.9% of mosquitoes were infected with any larval stage of W. bancrofti in the head or thorax in 362 dissections in the untreated villages compared to 4.7% infected in 549 dissections in the ivermectin treated villages (Mantel-Haenszel ChiSquare 0.02, P = 0.9). We concluded that ivermectin annual therapy for onchocerciasis has not interrupted transmission of Wuchereria bancrofti (the causative agent of LF in Nigeria). more...

The rapid immunochromatographic card test (ICT) for Wuchereria bancrofti circulating filarial antigen is being used to map areas endemic for lymphatic filariasis. However, the ICT is expensive; thus, surveys based on this test must be relatively limited. Our study was conducted to determine if village-based hydrocele surveys could be used to supplement the ICT surveys in the mapping activities. We compared in 144 Nigerian villages the two assessment methods, ICT and examination for clinical hydrocele, in random samples of 30 adults selected using a procedure that obtained 15 younger males (reported age = 16-39 years old) and 15 older males (or = 40 years), based on the assumption that hydrocele rates may be more prevalent in older age groups. The men were asked if they had scrotal swelling, then examined and tested by the ICT. We found a weakly positive correlation between village prevalence determined by the ICT and hydrocele (r = 0.041, P0.001). Only villages with hydrocele rates of 20% or greater were also consistently classified as having endemic filariasis by the ICT. There was no correlation between an individual's ICT positivity and clinical presence of hydrocele, and questioning about scrotal swelling was not predictive for presence of hydrocele. More research is needed to determine if community level hydrocele prevalence surveys can offer an economical and broadly applicable supplement to the ICT for determining the endemicity of filariasis. more...

This paper describes a pilot initiative to incorporate lymphatic filariasis (LF) elimination and urinary schistosomiasis (SH) control into a mature onchocerciasis control program based on community-directed ivermectin treatment in central Nigeria. In the same districts having onchocerciasis we found LF (as determined by blood antigen testing in adult males) in 90% of 149 villages with a mean prevalence of 22.4% (range 0-67%). Similarly, SH, as determined by dipstick reagent testing for blood in urine from school children, was found in 91% of 176 villages with a mean orevalence in school age children of 24.4% (range 0-87%). Health education and treatment interventions for SH resulted in 52,480 cumulative praziquantel treatments, and 159,555 combined onchocerciasis and LF treatments (with ivermectin and albendazole) as of the end of 2000. Treatments for onchocerciasis and LF were separated by at least 1 week from treatments for SH. There was no negative impact on the coverage of the onchocerciasis program by the addition of LF and SH activities. more...

Periodic mass treatment with ivermectin in endemic communities prevents eye and dermal disease due to onchocerciasis. As part of an international global partnership to control onchocerciasis, The Carter Center's Global 2000 River Blindness Program (GRBP) assists the ministries of health in ten countries to distribute ivermectin (Mectizan, donated by Merck & Co.). The GRBP priorities are to maximize ivermectin treatment coverage and related health education and training efforts, and to monitor progress through regular reporting of ivermectin treatments measured against annual treatment objectives and ultimate treatment goals (e.g., full coverage, which is defined as reaching all persons residing in at risk villages who are eligible for treatment). Since the GRBP began in 1996, more than 21.2 million ivermectin treatment encounters have been reported by assisted programs. In 1999, more than 6.6 million eligible persons at risk for onchocerciasis received treatment, which represented 96% of the 1999 annual treatment objective of 6.9 million, and 78% of the ultimate treatment goal in assisted areas. more...

In central Nigeria Anopheles mosquitoes transmit malaria and lymphatic filariasis (LF). The strategy used for interrupting LF transmission in this area is annual mass drug administration (MDA) with albendazole and ivermectin, but after 8 years of MDA, entomological evaluations in sentinel villages showed continued low-grade mosquito infection rates of 0.32%. After long-lasting insecticidal net (LLIN) distribution by the national malaria program in late 2010, however, we were no longer able to detect infected vectors over a 24-month period. This is evidence that LLINs are synergistic with MDA in interrupting LF transmission., Author Summary In Plateau and Nasarawa states in central Nigeria, 4 million persons are threatened by a mosquito-transmitted parasitic disease called lymphatic filariasis (LF). LF can lead to elephantiasis, a crippling condition in which the limbs and genitals often are grotesquely swollen or enlarged. In communities afflicted by this disease, as many as 10% can be affected with swollen limbs, and 50% of men can suffer from swollen genitals. These conditions have a devastating effect on the quality of life of victims, impacting them not only physically but also emotionally and economically. Through health education and community-delivered mass drug administration (MDA) with donated medicines, the Nigerian Ministry of Health and its Carter Center partners have been trying to stop mosquitoes from transmitting LF. LF transmission, as measured by mosquito dissections, dropped dramatically after 8 years of annual MDA. However, it was not until the malaria program distributed long-lasting insecticidal nets in 2010 that the LF parasite no longer appeared in mosquito dissections. No LF infected mosquito was found over a 24-month long surveillance period following long-lasting insecticidal net distribution. The study concluded that MDA and long-lasting insecticidal nets work together to halt the transmission of LF. more...

The current strategy for interrupting transmission of lymphatic filariasis (LF) is annual mass drug administration (MDA), at good coverage, for 6 or more years. We describe our programmatic experience delivering the MDA combination of ivermectin and albendazole in Plateau and Nasarawa states in central Nigeria, where LF is caused by anopheline transmitted Wuchereria bancrofti. Baseline LF mapping using rapid blood antigen detection tests showed mean local government area (LGA) prevalence of 23% (range 4–62%). MDA was launched in 2000 and by 2003 had been scaled up to full geographic coverage in all 30 LGAs in the two states; over 26 million cumulative directly observed treatments were provided by community drug distributors over the intervention period. Reported treatment coverage for each round was ≥85% of the treatment eligible population of 3.7 million, although a population-based coverage survey in 2003 showed lower coverage (72.2%; 95% CI 65.5–79.0%). To determine impact on transmission, we monitored three LF infection parameters (microfilaremia, antigenemia, and mosquito infection) in 10 sentinel villages (SVs) serially. The last monitoring was done in 2009, when SVs had been treated for 7–10 years. Microfilaremia in 2009 decreased by 83% from baseline (from 4.9% to 0.8%); antigenemia by 67% (from 21.6% to 7.2%); mosquito infection rate (all larval stages) by 86% (from 3.1% to 0.4%); and mosquito infectivity rate (L3 stages) by 76% (from 1.3% to 0.3%). All changes were statistically significant. Results suggest that LF transmission has been interrupted in 5 of the 10 SVs, based on 2009 finding of microfilaremia ≥1% and/or L3 stages in mosquitoes. Four of the five SVs where transmission persists had baseline antigenemia prevalence of >25%. Longer or additional interventions (e.g., more frequent MDA treatments, insecticidal bed nets) should be considered for ‘hot spots’ where transmission is ongoing., Author Summary Lymphatic filariasis is a mosquito transmitted disease that is best known for causing elephantiasis (grossly swollen legs and genitals). The current strategy for halting lymphatic filariasis in sub Saharan Africa is to establish programs that deliver 6 or more years of annual doses of tablets in community wide treatment programs (called mass drug administration). The tablets are safe, and donated by Merck & Co. and GlaxoSmithKline. We describe a mass drug administration program in central Nigeria that has, since 2000, provided over 23 million cumulative annual treatments to a population of 3.7 million persons. To assess what should be happening generally throughout the program area, lymphatic filariasis infection was monitored in ten ‘sentinel villages.’ In 2009, sentinel village monitoring showed that lymphatic filariasis infection had been reduced between 67–86% compared to levels present when the program began. However, these results were not as good as desired, and suggest that longer or increased efforts are needed beyond 6 years if lymphatic filariasis elimination is to be achieved. more...

Background Members of the Anopheles gambiae complex are important vectors of lymphatic filariasis (LF) in sub-Saharan Africa, but little is known about the relative contributions of all mosquitoes to lymphatic filariasis transmission in this area. Methods Over a 28 month period, mosquitoes were collected from 13 villages in Plateau and Nasarawa states in central Nigeria and dissected to determine W. bancrofti infection status. Wings and legs from a subset of the mosquitoes visually identified as A. gambiae s.l. were identified by PCR as either A. gambiae s.s. or A. arabiensis. Results A. gambiae s.s peaked in abundance during the rainy season while A. arabiensis predominated during drier parts of the year. Both species were found equally likely to be infected with the developing stages (L1-L3) of W. bancrofti (9.2% and 11.1%, respectively). Fewer A. funestus (1.1%, p < 0.001) were infected than A. gambiae s.l. Conclusion Understanding the relative contributions of morphologically indistinguishable species to LF transmission is essential if PCR is to be performed on mosquito pools. In the study area, the use of mosquito pools composed of A. gambiae sibling species would not be problematic, as both A. gambiae s.s. and A. arabiensis contribute equally to LF transmission. more...