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Matapo BB, Mpabalwani EM, Kaonga P, Simuunza MC, Bakyaita N, Masaninga F, Siyumbwa N, Siziya S, Shamilimo F, Muzongwe C, Mwase ET, Sikasunge CS. Lymphatic Filariasis Elimination Status: Wuchereria bancrofti Infections in Human Populations after Five Effective Rounds of Mass Drug Administration in Zambia. Trop Med Infect Dis 2023; 8:333. [PMID: 37505629 PMCID: PMC10383567 DOI: 10.3390/tropicalmed8070333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/22/2023] [Accepted: 05/23/2023] [Indexed: 07/29/2023] Open
Abstract
Lymphatic filariasis (LF), also commonly known as elephantiasis, is a neglected tropical disease (NTD) caused by filarial parasites. The disease is transmitted via a bite from infected mosquitoes. The bites of these infected mosquitoes deposit filarial parasites, Wuchereria or Brugia, whose predilection site is the lymphatic system. The damage to the lymph system causes swelling in the legs, arms, and genitalia. A mapping survey conducted between 2003 and 2011 determined LF as being endemic in Zambia in 96 out of 116 districts. Elimination of LF is known to be possible by stopping the spread of the infection through large-scale preventive chemotherapy. Therefore, mass drug administration (MDA) with diethylcarbamazine citrate (DEC) (6 mg/kg) and Albendazole (400 mg) for Zambia has been conducted and implemented in all endemic districts with five effective rounds. In order to determine whether LF prevalence has been sufficiently reduced to levels less than 2% antigenemia and less than 1% microfilaremia, a pre-transmission assessment survey (pre-TAS) was conducted. Therefore, post-MDA pre-TAS was conducted between 2021 and 2022 in 80 districts to determine the LF prevalence. We conducted a cross-sectional seroprevalence study involving 600 participants in each evaluation unit (EU) or each district. The study sites (sentinel and spot-check sites) were from districts that were the implementation units (IUs) of the LF MDA. These included 80 districts from the 9 provinces. A total of 47,235 people from sentinel and spot-check locations were tested. Of these, valid tests were 47,052, of which 27,762 (59%) were females and 19,290 (41%) were males. The survey revealed in the 79/80 endemic districts a prevalence of Wb antigens of 0.14% and 0.0% prevalence of microfilariae. All the surveyed districts had an optimum prevalence of less than 2% for antigenaemia, except for Chibombo district. The majority of participants that tested positive for Wuchereria bancrofti (Wb) Antigens (Ag) were those that had 2, 3, and 4 rounds of MDA. Surprisingly, individuals that had 1 round of MDA were not found to have circulating antigens of Wb. The study showed that all the surveyed districts, except for Chibombo, passed pre-TAS. This further implies that there is a need to conduct transmission assessment surveys (TASs) in these districts.
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Affiliation(s)
- Belem Blamwell Matapo
- School of Public Health, University of Zambia, Ridgeway Campus, Lusaka P.O. Box 50516, Zambia
- World Health Organization, Corner Andrew Mwenya/Beit Road, Lusaka P.O. Box 32346, Zambia
| | - Evans Mwila Mpabalwani
- School of Medicine, University of Zambia, Ridgeway Campus, Lusaka P.O. Box 50516, Zambia
| | - Patrick Kaonga
- School of Public Health, University of Zambia, Ridgeway Campus, Lusaka P.O. Box 50516, Zambia
| | - Martin Chitolongo Simuunza
- School of Veterinary Medicine, University of Zambia, Great East Road Campus, Lusaka P.O. Box 32379, Zambia
| | - Nathan Bakyaita
- World Health Organization, Corner Andrew Mwenya/Beit Road, Lusaka P.O. Box 32346, Zambia
| | - Freddie Masaninga
- World Health Organization, Corner Andrew Mwenya/Beit Road, Lusaka P.O. Box 32346, Zambia
| | - Namasiku Siyumbwa
- Ministry of Health Headquarters Ndeke House, Lusaka P.O. Box 30205, Zambia
| | - Seter Siziya
- Michael Chilufya Sata School of Medicine, Copperbelt University, Ndola P.O. Box 71191, Zambia
| | - Frank Shamilimo
- Ministry of Health Headquarters Ndeke House, Lusaka P.O. Box 30205, Zambia
| | - Chilweza Muzongwe
- Ministry of Health Headquarters Ndeke House, Lusaka P.O. Box 30205, Zambia
| | - Enala T. Mwase
- School of Veterinary Medicine, University of Zambia, Great East Road Campus, Lusaka P.O. Box 32379, Zambia
| | - Chummy Sikalizyo Sikasunge
- School of Veterinary Medicine, University of Zambia, Great East Road Campus, Lusaka P.O. Box 32379, Zambia
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Graves PM, Sheridan S, Scott J, Amosa-Lei Sam F, Naseri T, Thomsen R, King CL, Lau CL. Triple-Drug Treatment Is Effective for Lymphatic Filariasis Microfilaria Clearance in Samoa. Trop Med Infect Dis 2021; 6:tropicalmed6020044. [PMID: 33916264 PMCID: PMC8167748 DOI: 10.3390/tropicalmed6020044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/26/2021] [Accepted: 03/31/2021] [Indexed: 11/16/2022] Open
Abstract
Following the first triple-drug mass drug administration (MDA) for lymphatic filariasis in Samoa in 2018, unexpected persistence of microfilaria (Mf) positivity in 18 (15%) of 121 antigen-positive persons was observed in a nationwide household survey 1–2 months later. Of the 18 Mf positive persons, 14 reported taking the MDA, raising concerns about MDA efficacy. In 2019, 5–6 months after the 2018 survey, a monitored treatment study was done to evaluate directly observed weight-based treatment in these Mf positive individuals. Mf presence and density were assessed before and 7 days after treatment, using 1 mL membrane filtered venous blood, and 60 uL thick blood films on slides prepared from venous or fingerprick blood. All 14 participants were still Mf positive on filters from venous blood pre-treatment samples, but two were negative by slide made from the same samples. Mf were cleared completely by day 7 in 12 of 13 participants followed up, and by day 30 in the remaining participant. Filtered blood using EDTA samples (to reduce clumping of Mf) is preferred over slides alone for improving the likelihood of detecting Mf and estimating their density. The triple-drug MDA strategy was effective at clearing Mf when given and taken at the correct dose.
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Affiliation(s)
- Patricia M. Graves
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Cairns, QLD 4870 and Townsville, QLD 4811, Australia;
- Correspondence: ; Tel.: +61-(0)-424-096571
| | - Sarah Sheridan
- School of Public Health and Community Medicine, University of New South Wales, Sydney NSW 2033, Australia;
| | - Jessica Scott
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Cairns, QLD 4870 and Townsville, QLD 4811, Australia;
| | | | - Take Naseri
- Ministry of Health, Apia, Samoa; (T.N.); (R.T.)
| | | | - Christopher L. King
- Center for Global Health, School of Medicine and Veterans Affairs Administration, Case Western Reserve University, Cleveland, OH 44106, USA;
| | - Colleen L. Lau
- School of Public Health, The University of Queensland, Brisbane, QLD 4006, Australia;
- Research School of Population Health, The Australian National University, Canberra, ACT 2601, Australia
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