Assessing Transmission of Lymphatic Filariasis Using Parasitologic, Serologic, and Entomologic Tools after Mass Drug Administration in American Samoa

Mladonicky, Janice M.; King, Jonathan D.; Liang, Jennifer L.; Chambers, Eric; Pa’au, Molisamoa; Schmaedick, Mark A.; Burkot, Thomas R.; Bradley, Mark; Lammie, Patrick J.

doi:10.4269/ajtmh.2009.80.769

Cited by 42 publications

(37 citation statements)

References 23 publications

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“…Prevalence of CFA in a baseline survey in 1999 was 16.5% [19], and subsequent testing in four sentinel villages found CFA declining from 11.5% in 2001 to 0.95% in 2006 [20]. Prevalences in an additional four villages surveyed in 2006 were higher, ranging from 2.1% to 4.6% [20], [21], and a territory-wide serosurvey in 2007 found 2.3% CFA prevalence. Additional MDA activities took place during 2007–2010, but the level of MDA coverage during those years is unclear.…”

Section: Introductionmentioning

confidence: 96%

“…(The Bm14 antibody test used is an indicator of infection or exposure and may give a positive result prior to development of patent infections [30], [31], [32].) The serological tests found 3.7–4.6% of residents of the three villages were positive for CFA and 12.5–14.9% positive for antifilarial IgG4 antibody to the recombinant Bm14 antigen [21]. Dissection of approximately half of the Ae.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Xenomonitoring Using Mosquitoes to Map Lymphatic Filariasis after Mass Drug Administration in American Samoa

et al. 2014

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BackgroundMass drug administration (MDA) programs have dramatically reduced lymphatic filariasis (LF) incidence in many areas around the globe, including American Samoa. As infection rates decline and MDA programs end, efficient and sensitive methods for detecting infections are needed to monitor for recrudescence. Molecular methods, collectively termed ‘molecular xenomonitoring,’ can identify parasite DNA or RNA in human blood-feeding mosquitoes. We tested mosquitoes trapped throughout the inhabited islands of American Samoa to identify areas of possible continuing LF transmission after completion of MDA.Methodology/Principle FindingsMosquitoes were collected using BG Sentinel traps from most of the villages on American Samoa's largest island, Tutuila, and all major villages on the smaller islands of Aunu'u, Ofu, Olosega, and Ta'u. Real-time PCR was used to detect Wuchereria bancrofti DNA in pools of ≤20 mosquitoes, and PoolScreen software was used to infer territory-wide prevalences of W. bancrofti DNA in the mosquitoes. Wuchereria bancrofti DNA was found in mosquitoes from 16 out of the 27 village areas sampled on Tutuila and Aunu'u islands but none of the five villages on the Manu'a islands of Ofu, Olosega, and Ta'u. The overall 95% confidence interval estimate for W. bancrofti DNA prevalence in the LF vector Ae. polynesiensis was 0.20–0.39%, and parasite DNA was also detected in pools of Culex quinquefasciatus, Aedes aegypti, and Aedes (Finlaya) spp.Conclusions/SignificanceOur results suggest low but widespread prevalence of LF on Tutuila and Aunu'u where 98% of the population resides, but not Ofu, Olosega, and Ta'u islands. Molecular xenomonitoring can help identify areas of possible LF transmission, but its use in the LF elimination program in American Samoa is limited by the need for more efficient mosquito collection methods and a better understanding of the relationship between prevalence of W. bancrofti DNA in mosquitoes and infection and transmission rates in humans.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Molecular Xenomonitoring Using Mosquitoes to Map Lymphatic Filariasis after Mass Drug Administration in American Samoa

et al. 2014

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“…As humans are the only reservoir for W . bancrofti parasites, one such strategy is to monitor mosquitoes for evidence of LF larval stages [10,11]. Dissection and microscopic examination of mosquitoes is time consuming and labour-intensive, and cannot be routinely recommended for post-MDA surveillance for practical reasons.…”

Section: Introductionmentioning

confidence: 99%

Lymphatic Filariasis Elimination in American Samoa: Evaluation of Molecular Xenomonitoring as a Surveillance Tool in the Endgame

et al. 2016

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The Global Programme to Eliminate Lymphatic Filariasis has made significant progress toward interrupting transmission of lymphatic filariasis (LF) through mass drug administration (MDA). Operational challenges in defining endpoints of elimination programs include the need to determine appropriate post-MDA surveillance strategies. As humans are the only reservoirs of LF parasites, one such strategy is molecular xenomonitoring (MX), the detection of filarial DNA in mosquitoes using molecular methods (PCR), to provide an indirect indicator of infected persons nearby. MX could potentially be used to evaluate program success, provide support for decisions to stop MDA, and conduct post-MDA surveillance. American Samoa has successfully completed MDA and passed WHO recommended Transmission Assessment Surveys in 2011 and 2015, but recent studies using spatial analysis of antigen (Ag) and antibody (Ab) prevalence in adults (aged ≥18 years) and entomological surveys showed evidence of possible ongoing transmission. This study evaluated MX as a surveillance tool in American Samoa by linking village-level results of published human and mosquito studies. Of 32 villages, seropositive persons for Og4C3 Ag were identified in 11 (34.4%), for Wb123 Ab in 18 (56.3%) and for Bm14 Ab in 27 (84.4%) of villages. Village-level seroprevalence ranged from 0–33%, 0–67% and 0–100% for Og4C3 Ag, Wb123 Ab and Bm14 Ab respectively. PCR-positive Aedes polynesiensis mosquitoes were found in 15 (47%) villages, and their presence was significantly associated with seropositive persons for Og4C3 Ag (67% vs 6%, p<0.001) and Wb123 Ab (87% vs 29%, p = 0.001), but not Bm14 Ab. In villages with persons seropositive for Og4C3 Ag and Wb123 Ab, PCR-positive Ae. polynesiensis were found in 90.9% and 72.2% respectively. In villages without seropositive persons for Og4C3 Ag or Wb123 Ab, PCR-positive Ae. polynesiensis were also absent in 94.1% and 70.6% of villages respectively. Our study provides promising evidence to support the potential usefulness of MX in post-MDA surveillance in an Aedes transmission area in the Pacific Islands setting.

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“…Several other publications have evaluated the IgG4 antibody detection to the rBm14 antigen as a monitoring tool post-MDA; however, most of them have obtained the rBm14 antigen directly from Dr Gary Weil's laboratory in Washington DC before Cellabs Pty Ltd of Australia developed the new kit (CELISA) in 2006 [6,18,19]. A study conducted by Ramzy just after the 5th round of MDA in 2 Egyptian villages reported that the antibody prevalence rates can take several years to fall to low levels after MDA [6].…”

Section: Discussionmentioning

confidence: 99%

Surveillance of lymphatic filariasis 5 years after stopping mass drug administration in Menoufiya governorate, Egypt

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Hs²,

Ga³

et al. 2014

East Mediterr Health J

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The World Health Organization recommends that before lymphatic filariasis elimination in an area can be confirmed, an additional survey should be performed at least 5 years after stopping mass drug administration. The current study aimed to determine the status of lymphatic filariasis 5 years after cessation of the mass drug administration in 3 sentinel Egyptian villages in Menoufiya Governorate. The rapid immunochromatographic card test (ICT) and a new commercial antibody detection kit (CELISA®) were used. All 1321 primary-school children aged 6-7 years old were ICT negative but 27 children were antibody positive. All households surveyed in one village with the highest antibody prevalence were ICT negative, indicating an absence of lymphatic filariasis. The CELISA antibody kit needs more standardization and development to be useful under field conditions. We conclude that lymphatic filariasis is no longer a public health problem in these villages and other villages with similar epidemiological conditions.

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Assessing Transmission of Lymphatic Filariasis Using Parasitologic, Serologic, and Entomologic Tools after Mass Drug Administration in American Samoa

Cited by 42 publications

References 23 publications

Molecular Xenomonitoring Using Mosquitoes to Map Lymphatic Filariasis after Mass Drug Administration in American Samoa

Molecular Xenomonitoring Using Mosquitoes to Map Lymphatic Filariasis after Mass Drug Administration in American Samoa

Lymphatic Filariasis Elimination in American Samoa: Evaluation of Molecular Xenomonitoring as a Surveillance Tool in the Endgame

Surveillance of lymphatic filariasis 5 years after stopping mass drug administration in Menoufiya governorate, Egypt

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