Impact of Five Annual Rounds of Mass Drug Administration with Diethylcarbamazine and Albendazole on Wuchereria bancrofti Infection in American Samoa

Liang, Jennifer L.; King, Jonathan D.; Ichimori, Kazuyo; Handzel, Thomas; Pa’au, Molisamoa; Lammie, Patrick J.

doi:10.4269/ajtmh.2008.78.924

Cited by 36 publications

(31 citation statements)

References 16 publications

(22 reference statements)

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“…Regular monitoring of the effect of the programmes is essential to evaluate the progress, to make evidence based adjustments and to ultimately end the MDAs when specified programme stopping criteria have been met [13,14]. Thorough assessments and analyses of the effect of MDAs on transmission and human infection in sentinel sites have been documented, especially from countries using the DEC/albendazole combination such as Egypt [15], Papua New Guinea [16,17], American Samoa [18,19], India [20] and Samoa [21]. Many LF endemic countries in sub-Saharan Africa are co-endemic for onchocerciasis, and due to the potential risk of DEC induced side-effects in individuals with Onchocerca volvulus infections, use a combination of ivermectin and albendazole in their MDAs for LF control.…”

Section: Discussionmentioning

confidence: 99%

Lymphatic filariasis control in Tanzania: effect of six rounds of mass drug administration with ivermectin and albendazole on infection and transmission

et al. 2013

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BackgroundControl of lymphatic filariasis (LF) in most countries of sub-Saharan Africa is based on annual mass drug administration (MDA) with a combination of ivermectin and albendazole, in order to interrupt transmission. We present findings from a detailed study on the effect of six rounds of MDA with this drug combination as implemented by the National Lymphatic Filariasis Elimination Programme (NLFEP) in a highly endemic rural area of north-eastern Tanzania.MethodsThe effect of treatment on transmission and human infection was monitored in a community- and a school-based study during an 8-year period (one pre-intervention and 7 post-intervention years) from 2003 to 2011.ResultsBefore intervention, 24.5% of the community population had microfilariae (mf) in the blood, 53.3% had circulating filarial antigens (CFA) and 78.9% had specific antibodies to the recombinant filarial antigen Bm14. One year after the sixth MDA, these values had decreased considerably to 2.7%, 19.6% and 27.5%, respectively. During the same period, the CFA prevalence among new intakes of Standard 1 pupils in 10 primary schools decreased from 25.2% to 5.6%. In line with this, transmission by the three vectors (Anopheles gambiae, An. funestus and Culex quinquefasciatus) as determined by dissection declined sharply (overall vector infectivity rate by 99.3% and mean monthly transmission potential by 99.2% between pre-intervention and fifth post-intervention period). A major shift in vector species composition, from predominantly anopheline to almost exclusively culicine was observed over the years. This may be largely unrelated to the MDAs but may have important implications for the epidemiology of LF in the area.ConclusionsSix MDAs caused considerable decrease in all the measured indices for transmission and human infection. In spite of this, indices were still relatively high in the late period of the study, and it may take a long time to reach the recommended cut-off levels for interruption of transmission unless extra efforts are made. These should include increased engagement of the target population in the control activities, to ensure higher treatment coverage. It is expected that the recent initiative to distribute insecticide impregnated bed nets to every household in the area will also contribute towards reaching the goal of successful LF elimination.

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Section: Discussionmentioning

confidence: 99%

Lymphatic filariasis control in Tanzania: effect of six rounds of mass drug administration with ivermectin and albendazole on infection and transmission

et al. 2013

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“…The ICT positive, mf negative findings are not uncommon, 19 especially during the MDA phase of an LF elimination program. 7,25 However, a single 60 μL blood slide is less sensitive for detecting mf than are 1 mL blood filtration techniques, and true mf positives therefore may not have been identified. False negatives (mf positive, ICT negative) are unlikely given the reported high sensitivity of the ICT.…”

Section: Discussionmentioning

confidence: 99%

Evidence for Stopping Mass Drug Administration for Lymphatic Filariasis in Some, But Not All Local Government Areas of Plateau and Nasarawa States, Nigeria

King

Eigege

Umaru³

et al. 2012

The American Society of Tropical Medicine and Hygiene

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Abstract. An average of six annual rounds of ivermectin and albendazole were distributed in Plateau and Nasarawa States, Nigeria, to eliminate lymphatic filariasis. From 2007 to 2008, population-based surveys were implemented in all 30 local government areas (LGAs) of the two states to determine the prevalence of Wuchereria bancrofti antigenemia to assess which LGA mass drug administration (MDA) could be halted. In total, 36,681 persons from 7,819 households were examined for filarial antigen as determined by immunochromatographic card tests. Overall antigen prevalence was 3.05% (exact upper 95% confidence interval [CI] = 3.41%) with an upper 95% CI range by LGA of 0.50-19.3%. Among 3,233 children 6-7 years of age, overall antigen prevalence was 1.71% (exact upper 95% CI = 2.19%), too high to recommend generally halting MDA in the two-state area. However, based on criteria of 2% antigenemia among persons 2 years of age, stopping MDA was recommended for 10 LGAs.

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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%

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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Impact of Five Annual Rounds of Mass Drug Administration with Diethylcarbamazine and Albendazole on Wuchereria bancrofti Infection in American Samoa

Cited by 36 publications

References 16 publications

Lymphatic filariasis control in Tanzania: effect of six rounds of mass drug administration with ivermectin and albendazole on infection and transmission

Lymphatic filariasis control in Tanzania: effect of six rounds of mass drug administration with ivermectin and albendazole on infection and transmission

Evidence for Stopping Mass Drug Administration for Lymphatic Filariasis in Some, But Not All Local Government Areas of Plateau and Nasarawa States, Nigeria

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

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