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N Arunachalam

Publications and source records attributed to N Arunachalam.

At least 19 recordsLinked to original sources
PubMed1997

Virus isolation from wild-caught mosquitoes during a Japanese encephalitis outbreak in Kerala in 1996.

Out of 5357 wild-caught mosquitoes in 163 pools tested for virus using antigen capture ELISA and an insect-bioassay (inoculation into Toxorhynchites splendens larvae and identification by IFA using JE virus-specific monoclonal antibody), 16 flavivirus isolations were made of which 12 (75%) were identified as JE virus. Of the 12 JE virus isolations, 7 were from Culex tritaeniorhynchus, 3 from Mansonia uniformis and 1 each from Ma. indiana and Anopheles subpictus. Four isolations from Mansonia species for the first time reported here are noteworthy.

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PubMed1996

Mattancherry urban agglomeration, a diminishing focus of lymphatic filariasis in Kerala.

Parasitological survey conducted recently in Mattancherry, Kerala showed a low prevalence of microfilariae (mf), with a mf rate of 1.81%, compared to that of 1956 when the mf rate was 14.7%. No brugian infection was encountered in the present investigation, though both bancroftian and brugian infections were reported earlier. Culex quinquefasciatus, the vector of bancroftian filariasis was the most predominant (93.3%) mosquito species, and its infection and infectivity rates were 0.76% and 0.54% respectively. Mansonioides spp., the vectors of brugian filariasis constituted only 0.2% of the total mosquitoes and with no infection. The overall reduction in the prevalence of mf cases and vector infection rates over the years is attributed to the continued activities of the National Filaria Control Programme. The disappearance of brugian filariasis could mainly be due to the drastic reduction in the Mansonioides breeding habitats, as a result of rapid urbanization coupled with improved socio economic conditions.

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PubMed1996

Brackish water mosquito problem of Vypeen Island, Cochin, Kerala.

A preliminary study has shown that the marshy terrain and brackish water bodies associated with mangrove forests contributed profuse breeding of mosquitos in Vypeen island, causing a severe menace to the island population. A total of 14 species belonging to four genera viz, Aedes, Anopheles, Armigeres and Culex was recorded from different habitats. Culex sitiens was found to be the predominant mosquito in all the perennial breeding habitats. The extent of different habitats in the production of mosquitos, and its possible abatement, using environmental and/or biocontrol methods are discussed.

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PubMed1992

Observations on population density of Culex quinquefasciatus and transmission indices of Bancroftian filariasis during and after Integrated Vector Management strategy.

An Integrated Vector Management strategy, implemented as an alternative to the conventional control operations that include mainly chemical control in Pondicherry, South India, reduced very substantially the population density of Culex quinquefasciatus. This resulted in drastic decrease in the intensity of transmission of bancroftian filariasis transmitted by Culex quinquefasciatus and consequently the incidence of new infections in children of 0-5 age group was minimized. When the IVM strategy was withdrawn after five years of implementation and conventional control measures were re-adopted, resilience of Culex quinquefasciatus population was observed and human exposure to the risk of infection increased. The results suggest that maintenance of vector density at reduced levels for prolonged periods, is necessary to control infectious diseases like filariasis, which is difficult in the present day urban situations in developing countries. Hence the emphasis should be on chemotherapy to achieve control of lymphatic filariasis.

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PubMed1991

Infectivity of a mermithid nematode Romanomermis iyengari (Welch) in different conductivity levels under laboratory and field conditions.

Infectivity of R. iyengari was examined by exposing mosquito (Culex quinquefasciatus) larvae to the preparasite at different conductivity levels. The preparasite infected 63.5, 30, 11, 1.5 and 0.5% of the mosquito larvae respectively at 2000, 2500, 3000, 3300 and 3600 mu ho/cm. Although, 62-69% of the preparasite survived at 4000-5400 mu ho/cm, it did not infect. Application of preparasite to tree-holes resulted in 53-63% infection of Aedes albopictus larvae initially. On 6th day the infection level was 40% which decreased further to 7% by 15th day. The infection reappeared on 38th day indicating that R. iyengari has not only infected mosquito larvae as soon as they were applied to tree-holes in which the conductivity was 600-2800 mu ho/cm but also got established there.

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PubMed1990

Insecticidal activity of carbosulfan (OMS 3022) and pyraclofos (OMS 3040) against mosquitoes.

Carbosulfan (OMS 3022), a carbamate and pyraclofos (OMS 3040), an organophosphate were evaluated for their biological activity against vector mosquitoes, both in laboratory and field conditions. Carbosulfan (25% EC), was found to be active against adults and immatures of Culex quinquefasciatus, Anopheles stephensi and Aedes aegypti. The LD values for adults were 6.65, 5.19 and 8.35 micrograms/cm2 and LC 50values for immatures were 5.4 X 10(-5), 1.6 X 10(-4 and 5.4) X 10(-4) 50mg/1 respectively. Pyraclofos (50%) showed neither larvicidal nor adulticidal activities. The residual effect of carbosulfan (25% WP) on cement, thatch and mud surfaces at 400 mg (ai)/m2 lasted for 3, 16 and 21 weeks respectively. In the field, carbosulfan at 2.00 kg (ai)/ha resulted in complete control of C. quinquefasciatus larvae for a period of one week in cement tanks and less than a week in other polluted water bodies, such as cesspits, cesspools and drains. Pyraclofos was not effective at a dose of 2.00 kg (ai)/ha in any of the habitats.

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