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Shriram A.N.,Medical Port | Krishnamoorthy K.,Vector Control Research Center Indian Council of Medical Research | Sivan A.,Medical Port | Saha B.P.,Filaria and oVector Borne Diseases National Vector Borne Diseases Control Programme | And 2 more authors.
Acta Tropica | Year: 2014

Mass Drug Administration is being carried out in Andaman and Nicobar Islands, India since 2004. Cross sectional microfilaria (Mf) survey was conducted in Nancowry group of islands, the lone foci of diurnally sub periodic form of bancroftian filariasis in Nicobar district, to examine its eligibility for Transmission Assessment Survey (TAS). A total of 2561 individuals (coverage: 23.9%) were screened from five islands. The overall Mf prevalence was 3.28%. Except one island, all other islands recorded Mf prevalence >1%, ranging from 2.5% to 5.3%, indicating persistence of infection despite six annual rounds of MDA. Mf prevalence was age dependent and was higher among males, but not significantly different between genders. Age and gender specific analysis showed a significant reduction in all the age classes among females vis a vis pre-MDA prevalence while the reduction was significant only in 21-30 and 41-50 age classes in males. Exposure to day biting and forest dwelling Downsiomyia nivea can be attributed for the persistent infection besides non-compliance for MDA. Based on fits of modified negative binomial distribution, true prevalence of Mf carriers in the community was estimated to be 4.74%, which is markedly higher (about 24%) than the observed prevalence of 3.28%. Follow up of cohorts showed evidence of continued persistence of infection and acquisition of new infections post six rounds of MDA. As the Mf prevalence was above >1% in four of the five islands, this area is not eligible for TAS, warranting continuation of MDA. Mass DEC fortified salt is suggested as an adjunct to hasten elimination of infection. © 2014 Elsevier B.V.

Ramaiah K.D.,Vector Control Research Center Indian Council of Medical Research | Vanamail P.,Vector Control Research Center Indian Council of Medical Research
Transactions of the Royal Society of Tropical Medicine and Hygiene | Year: 2013

Background: While various studies provided insight into the impact of mass drug administration (MDA), information on the dynamics of the post-MDA threshold level lymphatic filariasis (LF) infection facilitates understanding its disappearance pattern and determining the duration of post-MDA monitoring and evaluation. Methods: The changes in microfilaraemia (Mf) prevalence and vector infection rates were monitored for four (2005-2008) and six years (2005-2010) respectively after stopping ten rounds of annual mass diethylcarbamazine (DEC) administration in a group of five villages located in South India. Four years after stopping MDA, circulating filarial antigenaemia (Ag) status among children and adults was also assessed in two villages. Results: Overall Mf prevalence (n 1/4 700) and vector infection rates (n1/4 803-3520) showed a declining trend. Two villages maintained zero Mf status in each of the four years, vector infection rate was zero from the third year onwards and Ag prevalence in adults was 0.4% (n 1/4 226). In two other villages despite persistence of Mf and vector infection there was zero vector infectivity rate during the third to sixth year and Ag prevalence among children (n 1/4 50) was nil. In the fifth village Mf prevailed at, 1.0% and Ag prevalence among 1-7 year old children was 4.6% (n 1/4 44) and vector infectivity rate during the sixth year was 0.1% (n 1/4 852). Conclusion: The incidence of sporadic new infections is evident in highly endemic communities such as the fifth village. However, there is uncertainty on the potential of the Ag positive children to reestablish infection. Six years of post-MDA monitoring and evaluation appears to be adequate to discern the status of transmission interruption and appropriate decision making. © Royal Society of Tropical Medicine and Hygiene 2013. All rights reserved.

Srinivasan R.,Vector Control Research Center Indian Council of Medical Research | Jambulingam P.,Vector Control Research Center Indian Council of Medical Research
Journal of Medical Entomology | Year: 2012

Phlebotomus (Phlebotomus) papatasi (Scopoli) collected in human dwellings from an agricultural villages Chaura, located in Gaya district, Bihar, India, showed morphological and anatomical variations. Male sand flies of this species exhibited variations in the genital structures, while females showed differences in the spermathecae and antenna segment three (A3). When the mitochondrial DNA of both male and female P. (P.) papatasi sensu lato population subjected to DNA barcoding, both the sexes of P. (P.) papatasi variants were found to be associated. The differences in the morphometric characteristics clearly constitutes preliminary evidence for infraspecific variation in P. (P.) papatasi s.l. population in India. © 2012 Entomological Society of America.

Srinivasan R.,Vector Control Research Center Indian Council of Medical Research | Jambulingam P.,Vector Control Research Center Indian Council of Medical Research
Journal of the American Mosquito Control Association | Year: 2011

A new species of phlebotomine sand fly, Sergentomyia (Parrotomyia) vadhanurensis, is described from Puducherry Union Territory, India, with illustrations of adult female and male specimens. This species was collected in tree holes, tree buttresses, termite mounds, cattle sheds, and human dwellings from rural areas. © 2011 by The American Mosquito Control Association, Inc.

Chandhiran K.,Vector Control Research Center Indian Council of Medical Research | Paily K.P.,Vector Control Research Center Indian Council of Medical Research
Biological Control | Year: 2015

Natural habitat of Romanomermis iyengari, an entomophilic mermithid nematode, is rice field. Parasitism of this nematode on mosquito larvae breeding in rice fields in Pondicherry, India, has been studied in 1979. The present study was to find out its persistence in the same habitat, after many years of agricultural practices. Evaluation of parasitism on mosquito larvae was carried out during two rice cultivation seasons at a schedule of 1. week prior, and 1 and 2. weeks after transplantation of paddy. Larval stages of mosquito species such as Culex tritaeniorhynchus, Culex vishnui, Anopheles vagus, and Anopheles subpictus showed parasitism of R. iyengari. Parasitism was the highest on C. tritaeniorhynchus with a maximum of 15.38% during season I and 17.85% during season II. Followed by this, it was on A. vagus (10.82% and 9.43%), C. vishnui (7.37% and 8.69%), and A. subpictus (3.70% and 6.36%). The overall density of mosquito larvae and level of parasitism of R. iyengari on them during season II was significantly higher than that of season I. The parasitism was maximum at 1. week before transplantation and showed a decreasing trend towards 2. weeks after transplantation, during both the seasons. The level of natural parasitism of R. iyengari during the present investigation was higher than that observed in the same ecosystem almost 35. years ago. This is clearly an indication towards the capability of the nematode to withstand several years of agricultural practices, including pesticide and agrichemical application. Hence, if applied at sufficient level and frequency, this nematode could act as a successful biocontrol agent against mosquitoes breeding in rice fields. © 2015 Elsevier Inc.

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