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Background: Integrated transmission assessment surveys (iTAS) have been recommended for evaluation of the transmission of both lymphatic filariasis (LF) and onchocerciasis as the prevalence of both diseases moves toward their respective elimination targets in Nigeria. Therefore, we conducted an iTAS between May and December 2017 in five local government areas (LGAs), also known as implementation units (IUs), in states of Cross River, Taraba and Yobe in Nigeria. Methods: The TAS comprised two phases: the Pre-iTAS and the iTAS itself. Three states (Cross River, Taraba and Yobe), comprising five LGAs and 20 communities that have completed five rounds of combined treatment with ivermectin and albendazole for LF and 12 total rounds of ivermectin, were selected for inclusion in the study. All participants were tested with the Filariasis Test Strip (FTS; Alere Inc.) and the Biplex rapid Diagnostic Test (RDT; identifying filaria antigens Ov16/Wb123; Abbott diagnosctics Korea Inc.). Pre iTAS included 100 children ages 5-9 in each 4 communities and 300 individuals ages 10 and older in a subset of two communities. For the iTAS, only LGAs where antigenemia prevalence in all sampled communities during the Pre-iTAS was < 2% for LF were selected. Results: Of the five LGAs included in the study, four met the cutoff of the Pre-iTAS and were included in the iTAS; the Ikom LGA was excluded from the iTAS due to antigenemia prevalence. A total of 11,531 school-aged children from 148 schools were tested for LF and onchocerciasis across these four LGAs, including 2873 children in Bade, 2622 children in Bekwara, 3026 children in Gashaka and 3010 children in Karim Lamido. Using the FTS, all samples from Bade and Karim Lamido were negative, whereas 0.2% of the samples from Bekwara and Gashaka were positive. Using the Biplex RDT, LF prevalence in Bade, Bekwara, Gashaka and Karim Lamido was < 0.1%, 0.5%, 0.4% and < 0.1%, respectively. Moreover, all samples from Bade and Karim Lamido were negative for onchocerciasis, whereas 3.1% and 1.8% of the samples from Bekwara and Gashaka were positive, respectively. Conclusion: This study has provided additional information on the current burden of onchocerciasis and LF in the four IUs sampled where mass drug administration (MDA) for both infections has been ongoing for years. The study identifies that LF-MDA can be safely stopped in all four of the IUs studied, but that MDA for onchocerciasis needs to continue, even though this may pose a challenge for LF surveillance. Based on the preliminary results from all four sites, this study has fulfilled the primary objective of determining the programmatic feasibility of an iTAS as a tool to simultaneously assess onchocerciasis and LF prevalence in areas co-endemic for the two infections that have completed the recommended treatment for one or both infections, and to make decisions on how to proceed. [ABSTRACT FROM AUTHOR]

Background More than 40 million people live in onchocerciasis-endemic areas in Nigeria. For at least 19 y, mass drug administration (MDA) with ivermectin was implemented with at least 65% total population coverage in Kaduna, Kebbi and Zamfara states. Impact surveys done using skin biopsies yielded no infections. Serological and entomological assessments were undertaken to determine if onchocerciasis transmission had been interrupted and MDA could be stopped. Methods The presence of onchocerciasis-specific immunoglobulin G4 antibody was measured by enzyme=linked immunosorbent assay conducted on dried blood spots collected from 5- to 9-year-old children resident in each state. O-150 polymerase chain reaction testing of Simulium damnosum s.l. heads for Onchocerca volvulus DNA was done on black flies collected by human landing capture and Esperanza window traps. Results A total of 9078 children were surveyed across the three states. A total of 6139 vectors were collected from Kaduna state, 129 from Kebbi state and 2 from Zamfara state; all were negative. Kebbi and Zamfara states did thousands of hours of black fly catching and intensive river prospecting. The resulting low fly catch was due to a low fly population incapable of sustaining transmission. Conclusion Onchocerciasis transmission has been interrupted and the three states meet World Health Organization thresholds: seropositivity in children <0.1% and <1/2000 infective black flies with 95% confidence. The 2.2 million people in Kaduna state and 4 million in Kebbi and Zamfara states no longer need ivermectin for onchocerciasis. [ABSTRACT FROM AUTHOR]

Background: Nigeria has a significant burden of lymphatic filariasis (LF) caused by the parasite Wuchereria bancrofti. A major concern to the expansion of the LF elimination programme is the risk of serious adverse events (SAEs) associated with the use of ivermectin in areas co-endemic with Loa filariasis. To better understand this, as well as other factors that may impact on LF elimination, we used Micro-stratification Overlap Mapping (MOM) to highlight the distribution and potential impact of multiple disease interventions that geographically coincide in LF endemic areas and which will impact on LF and vice versa. Methodology/Principal findings: LF data from the literature and Federal Ministry of Health (FMoH) were collated into a database. LF prevalence distributions; predicted prevalence of loiasis; ongoing onchocerciasis community-directed treatment with ivermectin (CDTi); and long-lasting insecticidal mosquito net (LLIN) distributions for malaria were incorporated into overlay maps using geographical information system (GIS) software. LF was prevalent across most regions of the country. The mean prevalence determined by circulating filarial antigen (CFA) was 14.0% (n = 134 locations), and by microfilaria (Mf) was 8.2% (n = 162 locations). Overall, LF endemic areas geographically coincided with CDTi priority areas, however, LLIN coverage was generally low (<50%) in areas where LF prevalence was high or co-endemic with L. loa. Conclusions/Significance: The extensive database and series of maps produced in this study provide an important overview for the LF Programme and will assist to maximize existing interventions, ensuring cost effective use of resources as the programme scales up. Such information is a prerequisite for the LF programme, and will allow for other factors to be included into planning, as well as monitoring and evaluation activities given the broad spectrum impact of the drugs used. Author Summary: Nigeria is estimated to have the highest burden of lymphatic filariasis (LF), a disease also known as elephantiasis, which is transmitted by mosquitoes and caused by the parasite Wuchereria bancrofti. The National LF Elimination Programme is planning to scale up the elimination programme through mass drug administration of ivermectin and albendazole. However, a major constraint to this expansion is the risk of serious adverse events (SAEs) associated with the use of ivermectin in areas co-endemic with Loa, the causative agent of tropical eye worm (loiasis). To better understand this and other factors that may impact on LF elimination, we collated and mapped all available LF data, and highlighted the overlaps with predicted loiasis prevalence distributions, onchocerciasis ivermectin treatment areas, and bed net distributions for malaria. This study provides a baseline overview for the LF Programme and will help to maximize existing disease interventions, ensuring cost effective use of resources as the programme scales up. [ABSTRACT FROM AUTHOR]

Background: Nigeria has a significant burden of lymphatic filariasis (LF) caused by the parasite Wuchereria bancrofti. A major concern to the expansion of the LF elimination programme is the risk of serious adverse events (SAEs) associated with the use of ivermectin in areas co-endemic with Loa filariasis. To better understand this, as well as other factors that may impact on LF elimination, we used Micro-stratification Overlap Mapping (MOM) to highlight the distribution and potential impact of multiple disease interventions that geographically coincide in LF endemic areas and which will impact on LF and vice versa. Methodology/Principal findings: LF data from the literature and Federal Ministry of Health (FMoH) were collated into a database. LF prevalence distributions; predicted prevalence of loiasis; ongoing onchocerciasis community-directed treatment with ivermectin (CDTi); and long-lasting insecticidal mosquito net (LLIN) distributions for malaria were incorporated into overlay maps using geographical information system (GIS) software. LF was prevalent across most regions of the country. The mean prevalence determined by circulating filarial antigen (CFA) was 14.0% (n = 134 locations), and by microfilaria (Mf) was 8.2% (n = 162 locations). Overall, LF endemic areas geographically coincided with CDTi priority areas, however, LLIN coverage was generally low (<50%) in areas where LF prevalence was high or co-endemic with L. loa. Conclusions/Significance: The extensive database and series of maps produced in this study provide an important overview for the LF Programme and will assist to maximize existing interventions, ensuring cost effective use of resources as the programme scales up. Such information is a prerequisite for the LF programme, and will allow for other factors to be included into planning, as well as monitoring and evaluation activities given the broad spectrum impact of the drugs used. [ABSTRACT FROM AUTHOR]

Background: The acceleration of the control of soil-transmitted helminth (STH) infections in Nigeria, emphasizing preventive chemotherapy, has become imperative in light of the global fight against neglected tropical diseases. Predictive risk maps are an important tool to guide and support control activities. Methodology: STH infection prevalence data were obtained from surveys carried out in 2011 using standard protocols. Data were geo-referenced and collated in a nationwide, geographic information system database. Bayesian geostatistical models with remotely sensed environmental covariates and variable selection procedures were utilized to predict the spatial distribution of STH infections in Nigeria. Principal Findings: We found that hookworm, Ascaris lumbricoides, and Trichuris trichiura infections are endemic in 482 (86.8%), 305 (55.0%), and 55 (9.9%) locations, respectively. Hookworm and A. lumbricoides infection co-exist in 16 states, while the three species are co-endemic in 12 states. Overall, STHs are endemic in 20 of the 36 states of Nigeria, including the Federal Capital Territory of Abuja. The observed prevalence at endemic locations ranged from 1.7% to 51.7% for hookworm, from 1.6% to 77.8% for A. lumbricoides, and from 1.0% to 25.5% for T. trichiura. Model-based predictions ranged from 0.7% to 51.0% for hookworm, from 0.1% to 82.6% for A. lumbricoides, and from 0.0% to 18.5% for T. trichiura. Our models suggest that day land surface temperature and dense vegetation are important predictors of the spatial distribution of STH infection in Nigeria. In 2011, a total of 5.7 million (13.8%) school-aged children were predicted to be infected with STHs in Nigeria. Mass treatment at the local government area level for annual or bi-annual treatment of the school-aged population in Nigeria in 2011, based on World Health Organization prevalence thresholds, were estimated at 10.2 million tablets. Conclusions/Significance: The predictive risk maps and estimated deworming needs presented here will be helpful for escalating the control and spatial targeting of interventions against STH infections in Nigeria. Author Summary: Infections with three kinds of parasitic worms—hookworm, roundworm, and whipworm—are collectively known as soil-transmitted helminths (STHs). These parasitic worm infections are widespread in Nigeria, but the exact distribution is poorly understood. In view of the global commitment to control STH infections, there is a need to accelerate the mapping of STH infections to guide control interventions, such as large-scale administration of deworming drugs. In this study, we collated survey data from the year 2011 for Nigeria. The data were utilized to predict the distribution of STH infection based on environmental and socioeconomic covariates, and employing a Bayesian geostatistical modeling approach. Our results indicated that STH infections are widely distributed across Nigeria with prevalence estimates as high as 83% for roundworm, 50% for hookworm, and 19% for whipworm infections at specific survey locations. We predict that 5.7 million school-aged children were infected with STHs. The numbers of deworming tablets for annual or bi-annual treatment of the school-aged population at local government areas level in Nigeria for 2011 were estimated to be 10.2 million. [ABSTRACT FROM AUTHOR]

Background: The acceleration of the control of soil-transmitted helminth (STH) infections in Nigeria, emphasizing preventive chemotherapy, has become imperative in light of the global fight against neglected tropical diseases. Predictive risk maps are an important tool to guide and support control activities. Methodology: STH infection prevalence data were obtained from surveys carried out in 2011 using standard protocols. Data were geo-referenced and collated in a nationwide, geographic information system database. Bayesian geostatistical models with remotely sensed environmental covariates and variable selection procedures were utilized to predict the spatial distribution of STH infections in Nigeria. Principal Findings: We found that hookworm, Ascaris lumbricoides, and Trichuris trichiura infections are endemic in 482 (86.8%), 305 (55.0%), and 55 (9.9%) locations, respectively. Hookworm and A. lumbricoides infection co-exist in 16 states, while the three species are co-endemic in 12 states. Overall, STHs are endemic in 20 of the 36 states of Nigeria, including the Federal Capital Territory of Abuja. The observed prevalence at endemic locations ranged from 1.7% to 51.7% for hookworm, from 1.6% to 77.8% for A. lumbricoides, and from 1.0% to 25.5% for T. trichiura. Model-based predictions ranged from 0.7% to 51.0% for hookworm, from 0.1% to 82.6% for A. lumbricoides, and from 0.0% to 18.5% for T. trichiura. Our models suggest that day land surface temperature and dense vegetation are important predictors of the spatial distribution of STH infection in Nigeria. In 2011, a total of 5.7 million (13.8%) school-aged children were predicted to be infected with STHs in Nigeria. Mass treatment at the local government area level for annual or bi-annual treatment of the school-aged population in Nigeria in 2011, based on World Health Organization prevalence thresholds, were estimated at 10.2 million tablets. Conclusions/Significance: The predictive risk maps and estimated deworming needs presented here will be helpful for escalating the control and spatial targeting of interventions against STH infections in Nigeria. [ABSTRACT FROM AUTHOR]

Introduction: In preparation for Mass Drug Administration by National Lymphatic Filariasis Elimination Programme, a baseline epidemiological investigation on lymphatic filariasis (LF) was conducted in two sentinel sites of Ogun State, Nigeria. The study was carried out in Ado-Odo Ota and Abeokuta South Local Government Areas (LGAs) to determine LF prevalence, microfilarial density and the abundance of Wucheraria bancrofti in the mosquito vectors. Methods: Microscopic examination of thick blood smears of 299 and 288 participants from Ado-Odo Ota and Abeokuta South LGAs was conducted. Visual observations of clinical manifestations of chronic infection and questionnaire administration were also conducted. Indoor resting mosquitoes were collected using the pyrethrum spray technique and CDC light traps and mosquitoes were dissected for filarial larvae. Results: Microfilaria prevalences were 4.0% and 2.4% in Ado-odo Ota and Abeokuta South LGAs. The microflarial density (mfd) was 30.6mf/ml and 23.9 mf/ml in the same areas. No clinical manifestations of the infection were found at both sites. Knowledge of LF by inhabitants was very low in the two areas. Anopheles gambiae s.l and Culex species mosquitoes were collected but none was found positive for stage L3 infective larvae. Conclusion: Mass awareness campaigns on the goal of mass drug administration, cause of LF, mode of transmission, the relationship between infection and clinical signs/symptoms is advocated so as to increase acceptance and support of the control programme by the community. [ABSTRACT FROM AUTHOR]

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 <0.1% in children (using both skin snip and OV16 antibody) and a rate of infective (L3) blackflies of <0.05%. Results: Among adult residents in sentinel sites, mean mf prevalence decreased by 99.37% from the 1991–1993 baseline of 42.95% (64/149) to 0.27% (2/739) in 2009 (p<0.001). The OV16 seropositivity of 3.52% (26/739) among this same group was over ten times the mf rate. No mf or nodules were detected in 4,451 children in sentinel sites and 'spot check' villages, allowing the exclusion of 0.1% infection rate with 95% confidence. Seven OV16 seropositives were detected, yielding a seroprevalence of 0.16% (0.32% upper 95%CI). No infections were detected in PCR testing of 1,568 Simulium damnosum s.l. flies obtained from capture sites around the six sentinel sites. Conclusion: Interruption of transmission of onchocerciasis in these five LGAs is highly likely, although the number of flies caught was insufficient to exclude 0.05% with 95% confidence (upper CI 0.23%). We suggest that ivermectin MDA could be stopped in these LGAs if similar results are seen in neighboring districts. 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. [ABSTRACT FROM AUTHOR]

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 <0.1% in children (using both skin snip and OV16 antibody) and a rate of infective (L3) blackflies of <0.05%. Results: Among adult residents in sentinel sites, mean mf prevalence decreased by 99.37% from the 1991–1993 baseline of 42.95% (64/149) to 0.27% (2/739) in 2009 (p<0.001). The OV16 seropositivity of 3.52% (26/739) among this same group was over ten times the mf rate. No mf or nodules were detected in 4,451 children in sentinel sites and ‘spot check’ villages, allowing the exclusion of 0.1% infection rate with 95% confidence. Seven OV16 seropositives were detected, yielding a seroprevalence of 0.16% (0.32% upper 95%CI). No infections were detected in PCR testing of 1,568 Simulium damnosum s.l. flies obtained from capture sites around the six sentinel sites. Conclusion: Interruption of transmission of onchocerciasis in these five LGAs is highly likely, although the number of flies caught was insufficient to exclude 0.05% with 95% confidence (upper CI 0.23%). We suggest that ivermectin MDA could be stopped in these LGAs if similar results are seen in neighboring districts. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]