This site needs JavaScript to work properly. Please enable it to take advantage of the complete set of features!
Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

NIH NLM Logo
Log in
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2016 May 19;10(5):e0004722.
doi: 10.1371/journal.pntd.0004722. eCollection 2016 May.

Programmatic Use of Molecular Xenomonitoring at the Level of Evaluation Units to Assess Persistence of Lymphatic Filariasis in Sri Lanka

Affiliations

Programmatic Use of Molecular Xenomonitoring at the Level of Evaluation Units to Assess Persistence of Lymphatic Filariasis in Sri Lanka

Ramakrishna U Rao et al. PLoS Negl Trop Dis. .

Abstract

Background: Sri Lanka's Anti Filariasis Campaign distributed 5 rounds of mass drug administration (MDA with DEC plus albendazole) to all endemic regions in the country from 2002-2006. Post-MDA surveillance results have generally been encouraging. However, recent studies have documented low level persistence of Wuchereria bancrofti in Galle district based on comprehensive surveys that include molecular xenomonitoring (MX, detection of filarial DNA in mosquitoes) results. The purposes of this study were to demonstrate the use of MX in large evaluation units (EUs) and to field test different mosquito sampling schemes.

Methodology/principal findings: Galle district (population 1.1 million) was divided into two EUs. These included a coastal EU with known persistent LF and an inland EU with little persistent LF. Mosquitoes were systematically sampled from ~300 trap locations in 30 randomly selected clusters (health administrative units) per EU. Approximately 28,000 Culex quinquefasciatus were collected with gravid traps and tested for filarial DNA by qPCR. 92/625 pools (14.7%) from the coastal EU and 8/583 pools (1.4%) from the inland EU were positive for filarial DNA. Maximum likelihood estimates (MLE) for filarial DNA rates were essentially the same when the same number of mosquito pools were collected and tested from 75, 150, or 300 trap sites (range 0.61-0.78% for the coastal EU and 0.04-0.07% for the inland EU). The ability to use a smaller number of trap sites reduces the cost and time required for mosquito sampling.

Conclusions/significance: These results suggest there is widespread persistence of W. bancrofti infection in the coastal Galle EU 8 years after the last round of MDA in 2006, and this is consistent with other data from the district. This study has shown that MX can be used by national programs to assess and map the persistence of W. bancrofti at the level of large EUs in areas with Culex transmission.

PubMed Disclaimer

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1
Filarial DNA rates (MLE with 95% confidence intervals) for mosquitoes collected in the coastal (panel A) and inland (panel B) EUs in Galle district. Lines with the same color show results from PHMs within a single MOOH area. Filarial DNA rates exceeded the target rate of 0.25% in 16 of 60 PHMs, and the upper confidence limit exceeded the target of 1% in all these 16 PHMs. The solid line in the panel A and B show the provisional target for MX. The dotted lines in the two panels are at the recommended upper confidence limits for filarial DNA rates in mosquitoes.
Fig 2
Fig 2. Percentages of mosquito trap locations in coastal PHM areas that yielded mosquito pools that were positive for filarial DNA by qPCR.
Bars with the same color show results from PHMs within a single MOOH area. Twenty-two % of trap locations captured mosquitoes with filarial DNA, but some locations had much higher rates.
Fig 3
Fig 3. Distribution of mosquito trapping locations tested for filarial DNA in 60 PHM areas in Galle district.
Molecular xenomonitoring results show trap locations with no mosquito pools positive for filarial DNA (coastal: green and inland: blue waypoints), and traps with one or more positive pools for filarial DNA are shown in red (in the coastal and inland EU areas).

References

    1. WHO (2015) Global programme to eliminate lymphatic filariasis: progress report, 2014. Wkly Epidemiol Rec 90: 489–504. - PubMed
    1. Ramaiah KD, Ottesen EA (2014) Progress and impact of 13 years of the global programme to eliminate lymphatic filariasis on reducing the burden of filarial disease. PLoS Negl Trop Dis 8: e3319 10.1371/journal.pntd.0003319 - DOI - PMC - PubMed
    1. Hooper PJ, Chu BK, Mikhailov A, Ottesen EA, Bradley M (2014) Assessing progress in reducing the at-risk population after 13 years of the global programme to eliminate lymphatic filariasis. PLoS Negl Trop Dis 8: e3333 10.1371/journal.pntd.0003333 - DOI - PMC - PubMed
    1. Rao RU, Nagodavithana KC, Samarasekera SD, Wijegunawardana AD, Premakumara WD, et al. (2014) A comprehensive assessment of lymphatic filariasis in Sri Lanka six years after cessation of mass drug administration. PLoS Negl Trop Dis 8: e3281 10.1371/journal.pntd.0003281 - DOI - PMC - PubMed
    1. Ramzy RM, El Setouhy M, Helmy H, Ahmed ES, Abd Elaziz KM, et al. (2006) Effect of yearly mass drug administration with diethylcarbamazine and albendazole on bancroftian filariasis in Egypt: a comprehensive assessment. Lancet 367: 992–999. - PubMed

Publication types

MeSH terms

Full text links
Public Library of Science full text link Public Library of Science Free PMC article
Cite

AltStyle によって変換されたページ (->オリジナル) /