[Show abstract][Hide abstract] ABSTRACT: Dengue and chikungunya are important arboviral infections in the Andaman Islands. Competent vectors viz. Aedes aegypti and Aedes albopictus are widely prevalent. The most effective proven method for interrupting the transmission of these arboviruses is vector control, mediated through insecticides. Currently, DDT and temephos are the insecticides used for vector control in these islands. Lack of information on susceptibility necessitated assessing the susceptibility profile of A. aegypti and A. albopictus. F1 generation of adult and larvae were assayed, and LT50 and LT90 values were interpreted following the World Health Organization (WHO) protocol. Adults were found resistant to DDT-4 % while susceptible to dieldrin-0.4 %. Against organophosphates, both showed resistance to fenitrothion but susceptible to malathion-5 %. Both species showed resistance to carbamate and bendiocarb-0.1 % while susceptible to propoxur-0.1 %. Of the four synthetic pyrethroids, both were susceptible to deltamethrin-0.05 %, while resistant to permethrin-0.75 %, lambdacyhalothrin-0.05 % and cyfluthrin-0.15 %. Larvae of both species showed resistance to temephos at 0.02 mg/L but susceptible to malathion at 1 mg/L and fenthion at 0.05 mg/L. Currently, there is no prescribed WHO dose for adult-insecticide susceptibility testing. The emergence of resistance to DDT and temephos in the vector population poses a challenge to the on-going vector control measures. The results highlight the need for monitoring resistance to insecticides in the vector population. Impetus for source reduction and alternative choices of control measures are discussed for tackling future threat of arboviral infections in these islands.
Parasitology Research 09/2015; 114(12). DOI:10.1007/s00436-015-4717-3 · 2.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mosquito foraging behavior is a determinant of host-vector contact and has an impact on the risk of arboviral epidemics. Therefore, blood-feeding patterns is a useful tool for assessing the role in pathogen transmission by vector mosquitoes. Competent vectors of dengue and chikungunya viz. Aedes aegypti and Aedes albopictus are widely prevalent in the Andaman and Nicobar archipelago. Considering the vector potential, medical importance of both these mosquito species and lack of information on host-feeding patterns, blood meal analysis of both these vector mosquitoes was undertaken. Biogents Sentinel traps were used for sampling blooded mosquitoes, for identifying the source of blood meal by agar gel-precipitin test. We identified vertebrate source of 147 and 104 blood meals in Ae. aegypti and Ae. albopictus from heterogeneous landscapes in South Andaman district. Results revealed that Ae. aegypti (88 %) and Ae. albopictus (49 %) fed on human and a small proportion on mammals and fowls, indicative of predominance of anthropophilism. Ae. aegypti predominantly fed on human blood (94.2 %-densely built urban, 89.8 %-low vegetation coverage, and 78.3 %-medium vegetation coverage). Anthropophilism in Ae. albopictus was maximal in densely built urban (90.5 %) and progressively decreased from low vegetation-vegetation/forested continuum (66.7, 36.4, and 8.7 %), indicating plasticity in feeding across these landscapes. Epidemiological significance of the findings is discussed.
Parasitology Research 07/2015; 114(9). DOI:10.1007/s00436-015-4634-5 · 2.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Lymphatic filariasis (LF) has become a major public health and socioeconomic problem in different parts of the globe. About 63% of the world's population with LF resides in Southeast Asia Region 1 and approximately 1/3rd of the affected people live in India. It is estimated that 554.2 million people in India are at risk of LF infection in 243 districts across 20 states and union territories. Global programme to eliminate lymphatic filariasis (GPELF) was launched in 2000 by the World Health Organization (WHO) with the goal to eliminate LF by 2020. India is committed to eliminate LF by 2015 by annual mass drug administration (MDA) with single dose of di-ethylcarbamazine (DEC) in combination with albendazole (ALB), for at least five years, along with home-based management of lymphoedema 2. The current benchmark for success as defined by WHO is <1% microfilaria prevalence in a community with five continued rounds of MDA with at least 60–70% drug compliance 3. In the present study, Tirukoilur block (11° 57' 58"N/ 79° 12' 9"E), Tamil Nadu, India with a human population of about 1,47,000, covering three Primary Health Centres (PHCs), viz. Ariyur, Edaiyur and T. Kunnathur, was surveyed for its LF status. The study was carried out during March 2009 in 32,056 households of 100 villages (urban and rural), as described earlier 4. A total of five rounds of MDA (2001, 2002, 2003, 2004 and 2007) using DEC+ALB was carried out in this area by the Tamil Nadu Public Health Department. The drug compliance during the fifth MDA (in 2007) was 86.32%. Parasitological survey was carried out in 10% of the population to determine microfilaraemia prevalence (MFP) and indoor resting Cx. quinquefasciatus adult female mosquitoes were collected as described by Sunish et al 4. The Institutional Ethical Committee approved the study design as per the national guidelines. The Epi-Info version 3.5.3 and SPSS for windows (version 16.0) was used for data analysis. Microfilaria (mf) positive individuals were found in 43 of 100 villages of the Tirukoilur block. Of these, 33 villages had >1% MFP. A total of 15,953 individuals were screened in the three PHCs, and the overall MFP was 1.21%, while the geometric mean intensity (GMI) was 0.0216. There was no significant difference (p>0.05) in the GMI of mf among the three PHCs. Higher prevalence and mean intensity of mf was observed in males than females. Similar observation was reported by other researchers 5. Prevalence increased with age, with a peak value of 2.05% in the age group of >60 yr (Table 1). In the 2–10 yr-old children, 44 mf carriers (0.67%) among 2397 subjects were identified, and there were no gender specific differences (p>0.05). A total of 4607 mosquitoes were collected by spending 432 man hours. Per man hour density was 6.85, 8.69 and 19.05 in Ariyur, Edaiyur and T. Kunnathur PHCs, respectively. There was no significant difference for infection and infectivity rates among the three PHCs (p>0.05). The transmission intensity index was 0.0278 in Ariyur, 0.0614 in Edaiyur and 0.0442 in T. Kunnathur. The Government of India has accorded a high priority for LF elimination through MDA programme. As per WHO guidelines, any area (usually an administrative unit) in an endemic country with mf prevalence of >1% is to be covered under the MDA programme 6. The administrative units in India are " districts " , and the overall prevalence of mf was <1% in the Villupuram district (study area is located in this district). Five rounds of MDA brought the mf prevalence to <1% in one of the three PHCs alone. Of the 100 villages surveyed, the mf prevalence was nil in 57 villages. There was 72.5% reduction in mf prevalence with a drug compliance of 86.32% in the 5th MDA (2007). After five MDAs, transmission was found to persist in few villages of this block, as indicated by the parasitological and entomological indices. Poor education level, population migration, lack of LF knowledge , high vector abundance and improper waste management were considered as added potential issues for ongoing transmission. Missed round of MDA was another factor 7. In the study area, drug compliance was effectively achieved (>85%) with appropriate village level IEC (Information Education and Communication) 8. Three more rounds of MDA along with integrated vector control reduced MFP further to 0.60% (4.40% in 2000 to 0.60% in 2013; 86% reduction) in a sample of villages surveyed (unpublished). However, similar endemic pockets need to be identified in order to implement supple
[Show abstract][Hide abstract] ABSTRACT: Background & objectives: One third of the world’s population is infected with one or more of the most common soil-transmitted helminths (STH). Albendazole (ALB) is being administered with diethyl carbamazine (DEC) in filariasis endemic areas to eliminate lymphatic filariasis (LF) and helminth infections. In this study, the cumulative impact of seven annual rounds of mass drug administrations (MDA) of DEC and ALB on STH infection in school children in selected villages in southern India was determined.
Methods: During 2001-2010, seven MDAs were implemented by the Tamil Nadu state health department, India. LF and STH infections were monitored in school children from 18 villages of the two treatment arms (viz, DEC alone and DEC+ALB). Kato-Katz cellophane quantitative thick smear technique was employed to estimate STH infections at three weeks, six months and one year post MDA.
Results: Prior to treatment, an overall STH prevalence was 60 per cent. After each MDA, infection markedly reduced at three weeks post-treatment in both the arms. The prevalence increased at six months period, which was maintained up to one year. After seven rounds of MDA, the infection reduced from 60.44 to 12.48 per cent in DEC+ALB arm; while the reduction was negligible in DEC alone arm (58.77 to 52.70%).
Interpretation & conclusions: Seven rounds of MDA with DEC+ALB reduced the infection load significantly, and further sustained low level of infection for 10 years. However, complete parasite elimination could not be achieved. To curtail STH infection in the community, MDA should be regularized and environmental sanitation measures need to be improved by effective community-based campaigns.
The Indian Journal of Medical Research 04/2015; 141(3):330-339. DOI:10.4103/0971-5916.156622 · 1.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The National Programme for the Elimination of Lymphatic Filariasis is underway in the endemic districts of Tamil Nadu State, South India, since 2001. Annual mass drug administration (MDA) was carried out by the state health department to all eligible individuals. The impact of MDAs on transmission parameters was evaluated in 2 revenue blocks, viz, one with DEC alone and the other with a combination of albendazole. After 10 years with 6 annual MDAs, the transmission indices reached low levels in both treatment arms, but still persisted. However, the DEC alone arm showed higher transmission rates, compared to the DEC + ALB arm. Few villages which demonstrated persistent transmission need to be targeted with an additional control measure viz, vector control, to achieve LF elimination. It is evident from the 10 year period of the study that inclusion of albendazole along with DEC has significantly reduced the transmission indices to almost nil level, as compared to DEC alone.
Parasitology International 12/2014; 64(1). DOI:10.1016/j.parint.2014.08.005 · 1.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Arboviral infections, viz. dengue and chikungunya are prevalent in the Andaman & Nicobar Islands. During post-tsunami developmental activities, large plastic tanks were provided to the native, Nicobarese tribal households of Car Nicobar Island, to store water for domestic use. These tanks form an ideal breeding source for mosquitoes, especially the vectors of dengue/chikungunya viruses, and few cases of IgM ELISA positives for these infections were identified from this island. In view of this scenario, a survey was carried out to determine the prevalence of these mosquito vectors. Ten randomly selected clusters (neighborhoods with 50 houses each) were surveyed. Each household was inspected for the water holding receptacles. This was the first attempt to determine the prevalence and distribution of the vectors of dengue/chikungunya virus in this Island, against the backdrop of various post tsunami rehabilitation and developmental activities. The stegomyia indices with respect to houses and containers were high during the winter and post-monsoon periods (House Index and Container Index were 69.40 and 46.41 in winter, while 54.40 and 39.49 in post-monsoon). Large plastic tanks (500–1000 l capacity) recorded the highest Breteau Index during all the four seasons. This habitat was observed to support four mosquito species, of which 52% constituted Aedes albopictus. The pupae/person index ranged from 0 to 0.2946. A community-based control approach with multiple stakeholders is envisaged to prevent the vector breeding. This approach would be feasible and effective, with active participation of the tribal chieftain along with village headmen.
[Show abstract][Hide abstract] ABSTRACT: Under the Global Programme to Eliminate Lymphatic Filariasis (LF), mass drug administration (MDA) is being implemented in Tamil Nadu, south India, by the State health machinery. The impact of six annual rounds of MDA using diethylcarbamazine (DEC) with and without albendazole (ALB) on filarial infection (microfilaraemia prevalence-MFP; antigenaemia prevalence-AGP) in paediatric population of 2-9 years was determined in two revenue blocks, with a population of 321 000. After each MDA, 300-400 children were screened for filarial infection. After six MDAs, an overall MFP reduction of 84.67% and 57.95% was observed in DEC+ALB and DEC alone arms, respectively. Corresponding AGP reductions were 72.88% (p < 0.001) and 41.51% (p = 0.023). Observation of microfilaraemic children after six MDAs (0.32% in DEC+ALB; 0.75% in DEC alone), necessitates the need for supplementary control strategies (viz., vector control), in order to achieve the goal of LF elimination.
[Show abstract][Hide abstract] ABSTRACT: Lymphatic filariasis (LF) is endemic in the Andaman and Nicobar islands, including the lone foci for a diurnally sub-periodic form of Wuchereria bancrofti in the Nancowry group of islands. A programme to eliminate LF was launched in 2004 by the Directorate of Health Services, Andaman and Nicobar Administration which involved a single annual mass drug administration (MDA) using diethylcarbamazine (DEC) with albendazole. So far, eight rounds of MDA have been implemented through the Public Health Care network. The pattern of antifilarial drug distribution and compliance achieved in the on-going LF elimination programme in these islands has been assessed. This is the first systematic effort undertaken in these remote islands to assess the coverage and compliance with the LF elimination programme. This study covered 900 households in each of the 3 districts. There were a largest number of side effects in the Nicobar district (6.4%). Non-consumption of drugs ranged from 18.6% (Nicobar) to 42% (North and Middle Andaman). A survey revealed that almost 95.3% of the respondents had heard about MDA from the drug distributors. Therefore, the distributors should be involved in programmes designed to educate the community at risk of acquiring filarial infection and the possible side effects of the drugs.
Tropical Doctor 04/2013; 43(1):30-2. DOI:10.1177/0049475513482123 · 0.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background & objectives:
Wolbachia are common intracellular bacteria that are found in arthropods and nematodes. These endosymbionts are transmitted vertically through host eggs and alter host biology in diverse ways, including the induction of reproductive manipulations, such as feminization, parthenogenesis, male killing and sperm-egg incompatibility. Since they can also move horizontally across species boundaries, Wolbachia is gaining importance in recent days as it could be used as a biological control agent to control vector mosquitoes or for paratransgenic approaches. However, the study of Wolbachia requires sophisticated techniques such as PCR and cell culture facilities which cannot be affordable for many laboratories where the diseases transmitted by arthropod vectors are common. Hence, it would be beneficial to develop a simple method to detect the presence of Wolbachia in arthropods.
In this study, we described a method of staining Wolbachia endobacteria, present in the reproductive tissues of mosquitoes. The reliability of this method was compared with Gram staining and PCR based detection.
The microscopic observation of the Gimenez stained smear prepared from the teased ovary of wild caught and Wolbachia (+) Cx. quinquefasciatus revealed the presence of pink coloured pleomorphic cells of Wolbachia ranging from cocci, comma shaped cells to bacillus and chain forms. The ovaries of Wolbachia (-) cured mosquito did not show any cell. Although Gram's staining is a reliable differential staining for the other bacteria, the bacterial cells in the smears from the ovaries of wild caught mosquitoes did not take the stain properly and the cells were not clearly visible. The PCR amplified product from the pooled remains of wild caught and Wolbachia (+) Cx. quinquefasciatus showed clear banding, whereas, no banding was observed for the negative control (distilled water) and Wolbachia (-) Cx. quinquefasciatus.
Interpretation & conclusion:
The Gimenez staining technique applied, could be used to detect the members of the endobacteria Wolbachia easily, even in a simple laboratory without any special facilities or even in the field condition and for handling large number of samples in a shorter duration.
[Show abstract][Hide abstract] ABSTRACT: Understanding Wolbachia mosquito interactions have been recognized as an important concept to develop novel vector control strategies. The prevalence of Wolbachia endobacteria in a natural population of the filariasis vector Culex quinquefasciatus was determined by the polymerase chain reaction method. Earlier workers had estimated the infection rates of Wolbachia with only one or very few individuals per species. In our study large number of specimens were assayed, and a total of 750 adult Culex quinquefasciatus mosquitoes were collected from three south Indian villages of Tirukoilur and Mugaiyur blocks, monthly for a period of five months (December 2006 to April 2007) and screened for the presence of Wolbachia. The percentage prevalence in adult males ranged from 88% to 96%; while in females from 84% to 100%. An overall prevalence of 91.2% was observed. There was no significant difference observed in the proportion of mosquitoes positive for Wolbachia between males and females, and also between different months of the survey; except during the month of February '07. The wsp gene sequence of the Wolbachia strain of Cx. quinquefasciatus detected was BLAST analysed and showed 99% sequence similarity with Wolbachia sp. of Culex pipiens isolated from different geographical regions. Phylogenetic analysis based on wsp gene fragments showed that the present Wolbachia isolate was closely related with Wolbachia from Culex pipens pipiens, Niphotettix virescens (Order: Hemiptera) and Cnaphalocrosis medinalis (Order: Lepidoptera).
[Show abstract][Hide abstract] ABSTRACT: The World Health Assembly in 1997 has targeted the elimination of lymphatic filariasis (LF) by 2020, and in India the goal has been set for the year 2015 by annual single dose mass drug administration (MDA). The role of community empowerment in enhancing the drug compliance and bringing out the function of various methods used to disseminate the information on MDA to the villagers is focused. A longitudinal survey was carried out in nine villages in Tirukoilur block of Villupuram district, Tamil Nadu for filarial infection variables like microfilaraemia, antigenaemia, transmission indices before and after each MDA, to determine the drug impact. Prior to each MDA, health education campaigns with different approaches were carried out with community as the leading player. These IEC approaches were assessed after 4 MDAs for its perception in the community. After four rounds of MDA, there was a significant decline in the filarial infection variables. The microfilaraemia and antigenaemia declined by 59% and 67% respectively. The transmission indices lowered by 89% and 94% (in resting and landing catch of mosquitoes respectively). The decline in these variables, with a drug consumption rate of >80% was achieved due to the effective IEC campaigns prior to each MDA. After 4 MDAs almost 97% of the respondents were aware of lymphatic filariasis. The KAP survey in the rural villages revealed that the dissemination of MDA message through autorickshaw was the most effective, followed by school students' rally. Empowerment of community through the members of women self help groups and school students were observed to be integral to mass drug administration campaigns for the enhancement of drug compliance, thus leading to LF elimination.
[Show abstract][Hide abstract] ABSTRACT: Antifilarial drug combinations including ivermectin provide antifilarial activity with ancillary benefits on intestinal helminths and ectoparasites, such as chiggers and lice. The impact of single oral dose of antifilarial drugs, viz; (1) diethylcarbamazine (DEC) alone, (ii) DEC + albendazole (ALB), (iii) ivermectin (IVR) + DEC and (iv) IVR + ALB, was determined, on the head louse (Pediculus humanus capitis) in primary school children in a rural community in south India.
Primary school children (n = 534) of age 6-10 years from four villages of South India were examined for the presence of head lice before and after single dose of DEC + ivermectin drug combination. The effectiveness and the duration of cure sustained by these drugs were quantified. The head louse was examined by "combing method" during post-treatment periods at 15, 45, 60 and 75 days interval.
The antifilarial drug consumption rate was similar (96-98%) in all treatment arms. In pre-treatment survey the prevalence of head lice in children administered with DEC, DEC + ALB, IVR + DEC and IVR + ALB arm was 86%, 80%, 87% and 80%, respectively, with the latter two arms demonstrating significant reduction in louse infestation (P < 0.05) for 60 days.
Single dose with IVR combination demonstrates a greater impact in reducing head louse infestation in the endemic rural communities for nearly 60 days. Therefore, in regions such as Africa where ivermectin is part of the antifilariasis campaign, this drug will have an additional benefit in reducing head lice infestation.
International journal of dermatology 11/2009; 48(11):1201-5. DOI:10.1111/j.1365-4632.2008.04059.x · 1.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The first chikungunya outbreak occurred in Kerala during 2006 affecting 14 districts, followed by another during May 2007 affecting almost whole of the State. Four of the worst affected districts viz, Pathanamthitta, Idukki, Kottayam and Thrissur were surveyed during 2007 to understand the magnitude of the problem of chikungunya fever, particularly clinical signs and symptoms.
A total of 1265 persons from 310 houses were surveyed door-to-door in 20 different localities representing four affected districts. The history and examination findings from 354 clinically diagnosed chikungunya cases were recorded. The symptoms recorded were fever, headache, myalgia, arthralgia, itch/rash, oedema, eye congestion, eye pain, oral ulcers, distaste, nausea, vomiting and haemorrhage.
The major symptoms were fever (100%), headache (97.5%), arthralgia (99.4%) and myalgia (99.4%). A significant difference was observed in oedema, distaste, nausea and headache among different age groups and these symptoms were reported to be lower (12.2-89.8%) in younger age group than in older age group (90.4-100%). No genderwise difference was observed for any of the symptoms. In clinically diagnosed chikungunya cases higher age group (>35 years) found with higher rate of severity with symptoms of oedema, distaste, nausea and headache when compared with lower age group (1-35 yr).
Chikungunya invaded Kerala State for the first time in 2006 and continues to be a major vector borne disease in the State. The clinical symptoms in affected cases highlighted high fever, sever myalgia and prolonged arthralgia, with occasional history of skin itch/rash (petechiae).
The Indian Journal of Medical Research 03/2009; 129(3):311-5. · 1.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To determine the role of vector control in further decreasing the transmission of bancroftian filariasis achieved by mass drug administration and the long-term impact on filariometric indices.
Three rounds of annual mass drug administration, with diethylcarbamazine and ivermectin, were complemented by vector control (mainly using polystyrene beads) in villages of Tirukoilur, south India, during 1995-99. Subsequently, drug administration is being carried out with diethylcarbamazine and albendazole or diethylcarbamazine alone. We evaluated the impact of mass drug administration used alone or in conjunction with vector control (from 1995 to 2005) on vector transmission indices (such as transmission intensity index, monthly biting rate, monthly transmission potential and annual transmission potential). We analysed data on filarial infection in the community to estimate the prevalence of microfilaraemia and antigenaemia using chi2 analysis and Fisher's exact test.
Vector density greatly decreased in villages where vector control was used as an adjunct to mass drug administration and almost no infective mosquitoes were found in the small numbers still remaining. Filarial antigenaemia was low and continued to decrease significantly in the age group 15-25 years in villages receiving mass drug administration with vector control in contrast to villages receiving only mass drug administration.
The gains of mass drug administration were sustained only with the integration of vector control measures. We advocate the incorporation of vector control in the Global Programme to Eliminate Lymphatic Filariasis as it can potentially decrease the time required for eliminating lymphatic filariasis.
Bulletin of the World Health Organisation 03/2007; 85(2):138-45. DOI:10.2471/BLT.06.029389 · 5.09 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The impact of single dose mass drug administration of diethylcarbamazine (DEC), DEC with albendazole (ALB), and ivermectin (IVR) with albendazole, was examined on the human bancroftian filarial infections in village scale trials in south India, from a follow-up study after 2 years. The treatment arms administered with DEC alone and DEC+ALB demonstrated long-term benefits in reducing microfilaraemia significantly (P<0.05), while antigenaemia reduction was negligible. The arm with ALB+IVR did not show such reductions. Among the antigenaemic and microfilaraemic individuals, 87% became amicrofilaraemic in DEC+ALB arm, which were higher than that observed in the other 2 treatment arms. Among amicrofilaraemics (but Ag+), nearly 35% cleared of infection in DEC+ALB, while 26% and 6% in DEC alone and IVR+ALB arms, respectively. The drug combination DEC+ALB was observed to demonstrate a significant impact in reducing filarial infection even after 2 years post treatment.
Parasitology International 10/2006; 55(3):233-6. DOI:10.1016/j.parint.2006.05.003 · 1.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: As part of the Global Programme for Elimination of Lymphatic Filariasis (GPELF), India is implementing mass drug administration (MDA) with annual single dose of diethylcarbamazine (DEC) with and without albendazole (ALB). The impact of MDAs on filarial infections and soil-transmitted helminth (STH) infections was assessed during a 3-year period in two communities, one with DEC + ALB and the other with DEC alone. Prior to each MDA (during 2001, 2002 and 2003), filarial indices (microfilaraemia and antigenaemia) were assessed from blood samples of 450-650 persons aged 2-25 years and STH infections in stool samples (Kato-Katz method) from 325 to 500 children aged 9-10 years. Mosquitoes resting indoors were collected to determine the filarial infection status. The microfilaraemia prevalence decreased significantly (P < 0.05) in both arms, with the highest decline in the DEC + ALB arm (72% vs. 51%). Decline in micrefilaria intensity was also higher in the DEC + ALB arm (81.4% vs. 48.5%). In this arm alone, the antigenaemia prevalence was reduced significantly (62%; P < 0.001). The reduction in STH prevalence was lower in the DEC alone arm (6.5%; NS) than in the DEC + ALB arm (70.9%; P < 0.001). Also, the egg reduction in DEC alone arm was only half that of DEC + ALB arm (49% vs. 97%). Our community-based follow-up study showed higher and sustained benefits with regard to filarial and STH infections for the two-drug arm over the DEC alone arm. The trends suggest that at least 10 MDAs may be necessary to achieve the goal of elimination.
Tropical Medicine & International Health 07/2006; 11(6):851-61. DOI:10.1111/j.1365-3156.2006.01625.x · 2.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The development and survival of immatures of Culex vishnui (Diptera: Culicidae) complex, vectors of Japanese encephalitis virus, were studied in transplanted rice, Oryza savita L., fields during three crop growing seasons. The total duration of development from the first instar to adult emergence varied from 6 to 8 d. Survival rate estimates ranged from 0.003 to 0.524, but they generally were <0.1. Unusually high survival rates (0.192-0.524) were observed in summer and long-term monsoon crop seasons during 1993. A multiple regression method using backward elimination was used to analyze the factors responsible for these variations. The model identified nine parameters related with survival rates that explained 99% of the variance. Area of water surface and hardness were negatively related, whereas green algae, notonectid adults, anisopterans, dytiscids, salinity, water depth, and dissolved oxygen were positively associated with immature survival.
Journal of Medical Entomology 04/2006; 43(2):185-91. DOI:10.1603/0022-2585(2006)043[0185:NSOISO]2.0.CO;2 · 1.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A longitudinal community-trial on the control of soil-transmitted helminths (STHs), as part of a lymphatic filariasis elimination campaign, was taken up in two revenue blocks of southern India in the years 2001 and 2002 to assess the impact of two annual single-dose mass drug administration (MDA) of diethylcarbamazine (DEC) + albendazole (ALB) with that of DEC alone. The prevalences and intensities of STHs were studied among cross-sectional samples of school children aged 9-10 years by using the Kato-Katz technique at baseline and 11 months after each MDA. The combined drug mass treatment produced a higher reduction in the prevalence (RIP) (51-77%) and the egg reduction rate (ERR) (92-98%) compared with 12-15% RIP and 58-62% ERR of DEC alone mass treatment. The effect of two-drug therapy after two annual treatments was relatively long lasting as shown by RIP and ERR indicating that the reinfection rates were relatively lower in this approach than single-drug therapy. This study demonstrates that mass drug co-administration of DEC + ALB in Global Programme for Elimination of Lymphatic Filariasis (GPELF) targeted at the community had a synergistic and sustainable effect against soil-transmitted helminthiasis and provided considerable 'beyond filariasis' benefits. The additional advantages accrued to the community underscore the importance of scaling-up GPELF to cover the entire population at risk.
Tropical Medicine & International Health 10/2004; 9(9):1030-5. DOI:10.1111/j.1365-3156.2004.01298.x · 2.33 Impact Factor