BackgroundControl of lymphatic filariasis (LF) in most of the sub-Saharan African countries is based on annual mass drug administration (MDA) using a combination of ivermectin and albendazole. Monitoring the impact of this intervention is crucial for measuring the success of the LF elimination programmes. This study assessed the status of LF infection in Rufiji district, southeastern Tanzania after twelve rounds of MDA.MethodsCommunity members aged between 10 and 79 years were examined for Wuchereria bancrofti circulating filarial antigens (CFA) using immunochromatographic test cards (ICTs) and antigen-positive individuals were screened for microfilaraemia. All study participants were examined for clinical manifestation of LF and interviewed for drug uptake during MDA rounds. Filarial mosquito vectors were collected indoor and outdoor and examined for infection with W. bancrofti using a microscope and quantitative real-time polymerase chain reaction (qPCR) techniques.ResultsOut of 854 participants tested, nine (1.1%) were positive for CFA and one (0.1%) was found to be microfilaraemic. The prevalence of hydrocele and elephantiasis was 4.8% and 2.9%, respectively. Surveyed drug uptake rates were high, with 70.5% of the respondents reporting having swallowed the drugs in the 2014 MDA round (about seven months before this study). Further, 82.7% of the respondents reported having swallowed the drugs at least once since the inception of MDA programme in 2000. Of the 1054 filarial vectors caught indoors and dissected to detect W. bancrofti infection none was found to be infected. Moreover, analysis by qPCR of 1092 pools of gravid Culex quinquefasciatus collected outdoors resulted in an estimated infection rate of 0.1%. None of the filarial vectors tested with qPCR were found to be infective.ConclusionAnalysis of indices of LF infection in the human population and filarial mosquito vectors indicated a substantial decline in the prevalence of LF and other transmission indices, suggesting that local transmission was extremely low if occurring at all in the study areas. We, therefore, recommend a formal transmission assessment survey (TAS) to be conducted in the study areas to make an informed decision on whether Rufiji District satisfied WHO criteria for stopping MDA.

HighlightsInterventions based on mass drug administration and insecticide-treated nets led to a marked decline in Wuchereria bancrofti circulating filarial antigen (CFA) in young school children.The official reported treatment coverage was relatively higher than the surveyed coverage.There has been an increase in ownership and utilization of insecticide-treated nets in the study areas.

Background Tanzania started implementing the WHO strategy of mass drug administration (MDA) with ivermectin and albendazole to eliminate lymphatic filariasis (LF) in Rufiji District, which had a baseline prevalence of 49% in 2000. This study was conducted in April 2015, six months after the latest MDA to establish the impact of MDA and utilisation of long-lasting insecticidal nets on the exposure rates of LF among standard-one children born within the implementation period of the LF elimination programme after 12 rounds. Methods A cross-sectional study for LF circulating filarial antigen (CFA) was performed in 5 primary schools from 5 different villages. A total of 659 standard-one pupils aged 6-9 years were recruited and screened for CFA using immunochromatographic test cards (ICT). Prior to blood sample collection, children were interviewed on their participation in the MDA. A finger prick whole blood sample (100 ml) drawn from each child was applied to ICT. Results were read after ten minutes for the presence of CFA. Also, the study involved 868 heads of household who were interviewed on their participation in MDA and utilisation of long-lasting insecticidal nets (LLINs). Results The ICT results were negative for CFA and suggest that there has been an interruption of exposure of children to LF transmission in the study area. More than half of the screened children (54.3%) participated in 2014 MDA round. Household surveyed MDA coverage was 57.4% for the 2014 MDA, below the minimum effective coverage recommended by WHO. Majority (92.5%) of households possessed and utilised LLINs. Of those who did not take the drugs in the last round, 88.7% possessed and utilised LLINs suggesting its synergistic effect with ivermectin and albendazole on LF transmission. Conclusions Additional MDA rounds and utilisation of LLINs in areas of high-baseline prevalence may result in considerable decreased lymphatic filariasis infection transmission.