Feeding pattern of anopheline and culicine mosquitoes in relation to biotopes and seasons in Delhi and environs.

In the studies to know the feeding pattern of various species of mosquitoes, a total of 7461 specimens comprising of Anopheles culicifacies (150), An. stephensi (61), An. subpictus (990), An. annularis (572), Culex quinquefasciatus (5217) and C. vishnui group (471) of mosquitoes were collected from different biotopes of selected localities in Delhi and environs during all the months of the year. The mosquito blood samples were processed by Gel diffusion technique to know the source of blood meal. Results of study revealed that the mosquito species tested in the study were by and large zoophilic and opportunistic feeders. The feeding behaviour was found to be highly influenced by biotopes from where the mosquitoes were collected, village and areas, different climatic seasons, sleeping behaviour of human beings and availability of alternative hosts particularly animal population. Overall anthropophilic index was found to be 24.66% for An. culicifacies, 20.96% for An. stephensi, 16.93% for An. subpictus, 9.96% for An. annularis, 26.33% for C. quinquefasciatus and 36.39% for C. vishnui group of mosquitoes. Feeding behaviour towards other animals viz: bovine, goat, dog, pig and bird for all these mosquito species in different months and biotopes e.g. human dwellings, cattle sheds and mixed dwellings; in different months and seasons of the year have been presented.

Prevalence of ixodid ticks in Nilgiri district of Tamil Nadu state (India).

The Nilgiri hills provides favourable ecological conditions for the propagation of haematophagous arthropods due to its richness in vegetation and animal fauna. A study was undertaken by the NICD during August to November 1996 on the prevalence of ectoparasitic ticks from different localities of the Nilgiris district of Tamil Nadu state. The ticks were hand picked from various domestic animals of the study area and identified. A total of 1232 adults and immatures of ticks were collected from domestic animals which comprised of the various species in the order of abundance Boophilus microplus, Haemaphysalis bispinosa, Riphicephalus haemaphysaloides and Riphicephalus sanguineus. Studies carried out in the grass lands, meadows and areas adjoining to tea plantations by flagging method revealed mainly immature stages and few adults of Riphicephalus Spp. and Haemaphysalis Spp. The public health importance of the above species have been discussed.

Breeding of Aedes aegypti and its Impact on Dengue/DHF in Rural Areas.

A survey was undertaken to ascertain the Aedes indices in Ashawati and Tauri villages of Faridabad and Gurgaon districts of Haryana state, India, during September 1996. The House Index, Container Index and Breteau Index recorded in Tauru village were 33.3, 21.0 and 40.0, while in Ashawati village these indices were 13.6, 2.8 and 10.3 respectively.

Dengue Outbreak in Ludhiana (Punjab), India,1996.

An outbreak of dengue fever/dengue haemorrhagic fever was reported from Ludhiana city in Punjab state, India, during October 1996. The outbreak started in the last week of September and lasted up to the first week of December. The number of cases reported during the outbreak was 720, with 19 deaths. A community survey revealed a very high attack rate of fever cases (4.10%). Serological tests suggested a recent dengue virus infection as seven serum samples out of nine tested were found to be positive. Aedes survey carried out in some of the affected localities revealed the presence of Aedes aegypti, a vector mosquito. The values of House and Container indices in Ludhiana city during the survey were 32.8% and 29.16% respectively. Breeding of Aedes mosquitoes was detected in various types of containers, mostly desertcoolers. To prevent such outbreaks in the state of Punjab and in the region, there is an urgent need for taking appropriate preventive measures and for disease/vector surveillance.