The Global Programme to Eliminate Lymphatic Filariasis (GPELF) was launched in 2000 with the goal of stopping transmission of lymphatic filariasis (LF) through yearly mass drug administration (MDA). Preliminary surveys of the human population in Mali suggested that Wuchereria bancrofti (W. bancrofti) infection was highly endemic in the Sikasso district. W. bancrofti prevalence and transmission in this region were confirmed in baseline human and entomologic studies in 6 villages in 2001 (prior to the start of yearly MDA with albendazole and ivermectin) and monitored yearly from 2002 to 2007 during MDA. Microfilaremia was determined by calibrated thick smear of night blood in adult volunteers and circulating filarial antigen was measured using immunochromatographic card test in children < 5 years of age. Mosquitoes were collected by human landing catch from July to December. None of the 686 subjects tested were microfilaremic 12 months after the sixth MDA round. More importantly, circulating antigen was not detected in any of the 120 children tested, as compared with 53% (103/194) before the institution of MDA. The number of infective bites/human/year decreased from 4.8 in 2002 to 0.04 in 2007, and only one mosquito containing a single infective larva was observed 12 months after the final MDA round. Whether this dramatic reduction in transmission will be sustained following cessation of MDA remains to be seen. After 7 annual rounds of mass drug administration (MDA) in 6 Malian villages highly endemic for Wuchereria bancrofti, the WHO criteria for stopping MDA were met and treatment ceased in 2008. Surveillance was initiated to detect recrudescence. Surveillance over the subsequent 5 years relied on a variety of methods including circulating filarial antigen (CFA) and antibody tests (Wb123) in 6-7 year olds. Entomological surveillance was performed through dissection of Anopheles gambiae complex specimens collected monthly using human landing catch (HLC) and pyrethrum spray catch (PSC) methods. Infection with Wuchereria bancrofti of Anopheles gambiae complex also used reverse-transcriptase polymerase chain reaction (RT-PCR) of pools of mosquitoes.here were increases in annual CFA prevalence rates using immunochromatographic tests (ICT) in children as surveillance progressed from 0% (0/289) in 2009, 2.7% (8/301) in 2011, 3.9% (11/285) in 2012 to 4.5% (14/309) in 2013 (Trend Chi2= 11.85, p= 0.0006). In 2012, when Wb123 antibody was assessed concurrently, there was antibody positivity in 5/285 (1.8%) that was similar to that of the CFA prevalence using an ELISA for CFA (5/285). By using HLC for entomologic assessments, only two Wb-infected Anopheles were observed from the 12,951 mosquitoes dissected, but none of these pools had infective L3 larvae. Using the PSC method and RT-PCR, no positive pools were observed. Although CFA positivity in children was used as the major surveillance tool, adults (8-65 years old) were also assessed. Unlike the children, the adults showed a decrease in the CFA prevalence from 4.9% (39/800) to 3.5% (28/795) and 2.8% (50/1,812) respectively in 2009, 2011 and 2012 (Trend Chi2= 7.361, p=0.0067). Some of the ICT positive individuals were found to be microfilaremic in 2009 (2.6% (1/39)) and 2011 (8.3% (3/36). Separate from these studies are others in which filarial-infected patients from leishmania co-endemic regions were assessed for innate responses to sandfly salivary products. To date, these products appear to be immunologically inert and follow-up studies to understand the basis of these are being performed.
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