Application of a household-based molecular xenomonitoring strategy to evaluate the lymphatic filariasis elimination program in Tamil Nadu, India

• Published in: PLoS neglected tropical diseases 2017-04, Vol.11 (4), p.e0005519-e0005519
• Main Authors: Subramanian, Swaminathan, Jambulingam, Purushothaman, Chu, Brian K, Sadanandane, Candasamy, Vasuki, Venkatesan, Srividya, Adinarayanan, Mohideen AbdulKader, Mohamed S, Krishnamoorthy, Kaliannagounder, Raju, Harikishan K, Laney, Sandra J, Williams, Steven A, Henderson, Ralph H
• Format: Article
• Language: English
• Subjects: Animals; Antibodies; Aquatic insects; Biology and Life Sciences; Care and treatment; Communicable Disease Control - methods; Councils; Culex; Culex - parasitology; Deoxyribonucleic acid; DNA; DNA, Helminth - isolation & purification; Elephantiasis, Filarial - epidemiology; Elephantiasis, Filarial - prevention & control; Evaluation; Family Characteristics; Filariasis; Households; Human populations; Humans; Independent sample; India - epidemiology; Infections; Infectious diseases; Lymphatic diseases; Medical research; Medicine and Health Sciences; Microfilariae - genetics; Microfilariae - isolation & purification; Monitoring; Mosquitoes; Parasites; Parasitic diseases; People and Places; Polymerase chain reaction; Pools; Prevention; Public health; Real-Time Polymerase Chain Reaction; Reproducibility; Research and Analysis Methods; Sampling; Strategy; Studies; Task forces; Trends; Tropical diseases; Virus-vector relationships; Wuchereria bancrofti - genetics; Wuchereria bancrofti - isolation & purification
• ISSN: 1935-2735; 1935-2727; 1935-2735
• DOI: 10.1371/journal.pntd.0005519

The monitoring and evaluation of lymphatic filariasis (LF) has largely relied on the detection of antigenemia and antibodies in human populations. Molecular xenomonitoring (MX), the detection of parasite DNA/RNA in mosquitoes, may be an effective complementary method, particularly for detecting signals in low-level prevalence areas where Culex is the primary mosquito vector. This paper investigated the application of a household-based sampling method for MX in Tamil Nadu, India. MX surveys were conducted in 2010 in two evaluation units (EUs): 1) a hotspot area, defined as sites with community microfilaria prevalence ≥1%, and 2) a larger area that also encompassed the hotspots. Households were systematically selected using a sampling interval proportional to the number of households in the EU. Mosquito pools were collected and analyzed by real-time polymerase chain reaction (qPCR). Two independent samples were taken in each EU to assess reproducibility of results. Follow-up surveys were conducted in 2012. In 2010, the proportion of positive pools in the hotspot EU was 49.3% compared to 23.4% in the overall EU. In 2012, pool positivity was significantly reduced to 24.3% and 6.5%, respectively (p