First outbreak of Japanese encephalitis in two villages of Dharmapuri district in Tamil Nadu.

BACKGROUND & OBJECTIVES: Three cases of Japanese encephalitis (JE) were reported for the first time from two villages in Krishnagiri Health Unit district of Tamil Nadu during November 1999. Two children died and one developed neurological sequelae. A serological survey was conducted in these villages to find out the prevalence of JE antibodies among children below 15 yr of age in addition to the epidemiological investigations. METHODS: The prevalence of haemagglutination inhibiting (HI) antibodies to JE virus (JEV), West Nile virus (WNV) and dengue-2 virus (DEN-2) was detected by HI test and IgM antibody capture ELISA (MAC ELISA) was performed to determine recent infections with JE virus. Adult mosquitoes were collected in the study villages and females of Culex pseudovishnui, C. tritaeniorhynchus and C. vishnui were tested for the presence of JE viral antigen by ELISA. RESULTS: Out of 146 sera samples from children below 15 yr, the prevalence of HI antibodies to JEV, WNV and DEN-2 virus was found to be 8.9, 3.4 and 6.85 per cent respectively and three children had IgM antibodies to JEV. Of the 13 species of mosquitoes identified, C. tritaeniorhynchus (30.8%) was the most abundant species in the study villages. Two pools of female C. tritaeniorhynchus were found to be positive for JEV antigen. Fogging with 2 per cent pyrethrum and residual spray with 10 per cent cyfluthrin were effective in reducing vector density. INTERPRETATION & CONCLUSIONS: Serological investigations revealed that the JE virus was predominant in the study villages. In addition, DEN-2 and WN viruses were also prevalent. Detection of JE virus specific IgM antibodies in three specimens and the presence of JE viral antigen in 2 pools of C. tritaeniorhynchus emphasized the need for constant surveillance and monitoring so as to prevent future large outbreaks.

Cost of mass annual single dose diethylcarbamazine distribution for the large scale control of lymphatic filariasis.

Economic analysis of the revised strategy to control lymphatic filariasis with mass annual single dose diethylcarbamazine (DEC) at 6 mg/kg body weight launched in one of the districts of Tamil Nadu in 1996 was carried out. This exploratory study, proposed for five years in 13 districts under 7 states on a pilot scale through the Department of Public Health is an additional input of the existing National Filaria Control Programme in India. A retrospective costing exercise was undertaken systematically from the provider's perspective following the completion of the first round of drug distribution. The major activities and cost components were identified and itemized cost menu was prepared to estimate the direct (financial) and indirect (opportunity) cost related to the implementation of the Programme. The total financial cost of this Programme to cover 22.7 lakh population in the district was Rs. 22.05 lakhs. The opportunity cost of labour and capital investment was calculated to be Rs. 7.98 lakhs. The total per capita cost was Rs. 1.32, with Rs. 0.97 and Rs. 0.35 as financial and opportunity cost respectively. Based on these estimates, the implementation cost of the Programme at Primary Health Centre (PHC) level was calculated and projected for five years. The additional financial cost for the existing health care system is estimated to be Rs. 27,800 per PHC every year. DEC tablets (50 mg) was the major cost component and sensitivity analysis showed that the cost of the Programme could be minimized by 20 per cent by switching over to 100 mg tablets. The analysis indicates that this Programme is a low-cost option and the results are discussed in view of its operational feasibility and epidemiological impact.

GIS based malaria information management system for urban malaria scheme in India.

A GIS based information management system has been developed to help Urban Malaria Control in India. The basic objective is to develop a model to assist planning and implementation of a suitable control measure. The system can help in: (i) identifying high receptive areas in time and space domain; (ii) identifying risk factors for high receptivity; (iii) monitoring and evaluating control measures. To demonstrate this system, information on 33 parameters and malaria cases has been attached to a digitised map of Dindigul, an urban town in Tamil Nadu. Functionalities of the system and its utility are described in this paper. A GIS based information management system ensures that if a localised spurt of the disease occurs, it can be associated rapidly with a likely cause, a specific vector, and a probable human source, so that appropriate preventive action can be taken to arrest any rising trend.

Impact of deltamethrin spraying on malaria transmission in Rameshwaram Island, Tamil Nadu State - India.

The impact of spraying Deltamethrin 2.5% w.d.p. @ 20 mg/m2 and its comparison with Malathion 25% w.d.p. @ 2 gr./m2 was assessed in Rameshwaram Island, Tamil Nadu. Monitoring of entomological and parasitological indices revealed that due to deltamethrin spray malaria transmission could be effectively interrupted and a significant reduction in malaria cases was achieved. P. falciparum cases also showed a significant reduction whereas in the comparison malathion areas reduction in malaria cases or in pf cases was not recorded.

Comparative results of non-operative multi-modal therapy for filarial lymphoedema.

A comparative analysis of different conservative modes of therapy for lymphoedema, largely of Filarial origin, was conducted in a trial therapy unit in Chengalpattu, a Filarial endemic district in Tamil Nadu. Results were compared using a single chambered intermittent pneumatic compression pump, heat therapy, and interferential therapy machines. The results showed improvement of limb size between 20% and 60% of possible reduction (where 100% would mean return of limb circumference to the same as that of the normal side). Pneumatic compression therapy, when used alone, showed the best results, which were significantly better than all others whether alone or in combination.

Ultra low volume (ULV) malathion application as a supplementary malaria control measure in two villages of South Arcot district, Tamil Nadu.

Ultra low volume (ULV) ground application of technical malathion as a supplementary malaria control measure was carried out in two riverine villages of South Arcot district, Tamil Nadu which had high persistent transmission since 1975. Malaria incidence was reduced to one fifth in villages under ULV malathion as against a 50% drop in the control village. The cost of ULV spray alone came to Rs. 1.07 per capita per year. ULV can be an effective supplementary measure in rural areas with specific problems.

Field evaluation of Bacillus sphaericus, H5a5b and B. thuringiensis var. israelensis, H-14 against the Bancroftian filariasis vector Culex quinquefasciatus, Say in Chennai, India.

Fortnightly application of Bacillus sphaericus (strain B101, serotype H5a5b) and B. thuringiensis var. israelensis (strain 164, serotype H-14) in two different waterways of Chennai @ 1 g/sq m surface area has resulted in significant reduction in both immature and adult densities of Culex quinquefasciatus Say. The use of these biolarvicides as biocontrol agents is suggested in the urban areas to control mosquitoes in general.

Effectiveness of community and health services-organized drug delivery strategies for elimination of lymphatic filariasis in rural areas of Tamil Nadu, India.

Lymphatic filariasis (LF) is targeted for global elimination. Repeated annual single-dose mass treatment with antifilarials has been recommended as the principal strategy to achieve LF elimination. This requires an effective and sustainable strategy to deliver the drug, diethylcarbamazine (DEC), to communities. In this study, a new drug delivery strategy - community-directed treatment (comDT) - was developed and implemented and its effectiveness compared with that of the traditional health services-organized drug delivery, in rural areas of Tamil Nadu, India. Qualitative and quantitative data showed that the communities and health services were able to distribute the drug in almost all villages. The drug distribution rate and treatment compliance rate of comDT and health services treatment were statistically compared after adjusting them for clustering. Under the comDT 68% (n=20 villages; range: 0-97%) of the population received DEC, compared with 74% (n=20 villages; range: 48-95%) with the health services treatment strategy (P > 0.05). However, only about 53% (range: 0-91%) of comDT recipients and 59% (range: 32-79%) of those who received DEC from the health services consumed the drug (P > 0.05). Although statistically not significant, the distribution and compliance rates were lower under the comDT strategy. Also, the strategy's operationalization appears to be difficult because of some social factors, and the tradition of communities' dependence on health services for treatment, whereas health services-organized distribution was much less cumbersome and found to be more acceptable to people. However, the distribution (74%) and compliance rates (59%) achieved by health services were also only moderate and may not be adequate to eliminate LF in a reasonable time frame. Health services manpower alone may not be sufficient to distribute the drug. We conclude that drug distribution by health services is the best option for India and participation of the community volunteers and village level government staffs in the programme is necessary to effectively distribute the drug and attain the desirable levels of treatment compliance to eliminate LF.

A programme to eliminate lymphatic filariasis in Tamil Nadu state, India: compliance with annual single-dose DEC mass treatment and some related operational aspects.

This paper reports on DEC distribution and compliance with treatment in a large-scale annual single-dose mass treatment programme to eliminate lymphatic filariasis in the south Indian state of Tamil Nadu. 76.9% of households (82.5% in rural areas and 58.0% in urban areas) were aware of drug distribution for control of filariasis. DEC was given to 70% (= distribution rate) (range 0-92%) of the population and 53.5% (range 12-89%) complied with treatment. The distribution rate was more than 75% in 74% of the villages and compliance was in the range of 51-75% in 76% of the villages. About 5% of the treated population reported side-effects. Distribution and compliance were higher in rural than urban areas and similar between males and females. Qualitative data showed that some socio-economic factors, logistic and drug-related problems and people's poor knowledge and perceived benefits of treatment played a role in a proportion of the population not receiving or taking the drug. The Tamil Nadu programme showed that large-scale repeated annual DEC mass treatment is feasible and that existing health services are capable of delivering the drug to all communities. While even poor to moderate compliance rates can reduce the vector transmission of infection to some extent, improved drug distribution and compliance with treatment are necessary to consolidate the gains of earlier rounds of treatment and achieve the goal of filariasis elimination within a reasonable time frame.

Silent spread of dengue and dengue haemorrhagic fever to Coimbatore and Erode districts in Tamil Nadu, India, 1998: need for effective surveillance to monitor and control the disease.

Dengue fever (DF) or dengue haemorrhagic fever (DHF) has not previously been reported in Coimbatore and Erode districts in Tamil Nadu in India. In 1998, 20 hospitalized cases of fever tested positive for dengue virus IgM and/or IgG antibodies. All of them had dengue-compatible illness, and at least four had DHF. Two of them died. Sixteen cases were below 10 years of age. The cases were scattered in 15 distantly located villages and 5 urban localities that had a high Aedes aegypti population. Although the incidence of dengue-like illness has not increased recently, almost 89% (95/107) of samples from healthy persons in the community tested positive for dengue IgG antibodies. The study showed that dengue has been endemic in the area, but was not suspected earlier. A strong laboratory-based surveillance system is essential to monitor and control DF/DHF.