Abstract
BackgroundPost-mass drug administration (MDA) surveillance during the lymphatic filariasis (LF) elimination program in Sri Lanka, revealed the re-emergence of brugian filariasis after four decades. This study was done with the objectives of investigating the epidemiology and age-specific vulnerability to infection. Surveillance was done using night blood smears (NBS) and the Brugia rapid test (BRT), to detect microfilaria (MF) and anti-Brugia IgG4 antibodies in blood samples collected from an age-stratified population enrolled from two high-risk study areas (SA)s, Pubudugama and Wedamulla in the Gampaha District. The periodicity of the re-emergent Brugia spp. was characterized by quantitative estimation of MF in blood collected periodically over 24 h using nucleopore-membrane filtration method.ResultsOf 994 participants [Pubudugama 467 (47.9%) and Wedamulla 527 (53%)] screened by NBS, two and zero cases were positive for MF at Pubudugama (MF rate, 0.43) and Wedamulla (MF rate, 0), respectively, with an overall MF rate of 0.2. Of the two MF positives, one participant had a W. bancrofti while the other had a Brugia spp. infection. Of 984 valid BRT test readings [Pubudugama (n = 461) and Wedamulla (n = 523)], two and seven were positive for anti-brugia antibodies by BRT at Pubudugama (antibody rate 0.43) and Wedamulla (antibody rate 1.34), respectively, with an overall antibody rate of 0.91. Both MF positives detected from SAs and two of three other Brugia spp. MF positives detected at routine surveillance by the National Anti-Filariasis Campaign (AFC) tested negative by the BRT. Association of Brugia spp. infections with age were not evident due to the low case numbers. MF was observed in the peripheral circulation throughout the day (subperiodic) with peak counts occurring at 21 h indicating nocturnal sub-periodicity.ConclusionsThere is the low-level persistence of bancroftian filariasis and re-emergence of brugian filariasis in the Gampaha District, Sri Lanka. The periodicity pattern of the re-emergent Brugia spp. suggests a zoonotic origin, which causes concern as MDA may not be an effective strategy for control. The importance of continuing surveillance is emphasized in countries that have reached LF elimination targets to sustain programmatic gains.
Highlights
Post-mass drug administration (MDA) surveillance during the lymphatic filariasis (LF) elimination program in Sri Lanka, revealed the re-emergence of brugian filariasis after four decades
Successful vector control activities targeted at Mansonia spp. mosquitoes resulted in complete clearance of brugian filariasis by 1967 [7]
Two MF positive cases were detected at Pubudugama (MF rate, 0.43%) and none were found at Wedamulla (MF rate 0), giving an overall MF rate of 0.2
Summary
Post-mass drug administration (MDA) surveillance during the lymphatic filariasis (LF) elimination program in Sri Lanka, revealed the re-emergence of brugian filariasis after four decades. Lymphatic filariasis (LF), a neglected tropical disease estimated by the World Health Organization to affect 940 million people in 54 countries, is targeted for elimination by 2020 [1,2,3]. LF is not a fatal disease, but it can cause significant morbidity It is the second leading parasitic cause of disability worldwide, estimated to cause 5.549 million disability-adjusted life years (DALYs) [4]. Three species of filarial worms, Wuchereria bancrofti, Brugia malayi and Brugia timori are known to cause lymphatic filariasis in humans [5]. Brugia malayi is prevalent in Southeast Asia and southwestern India (Kerala) [5]. Both W. bancrofti and B. malayi infections were prevalent in Sri Lanka in the past [7]. Successful vector control activities targeted at Mansonia spp. mosquitoes resulted in complete clearance of brugian filariasis by 1967 [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
