Predatory potential of Platynectes sp. (Coleoptera:Dytiscidae) on Aedes albopictus, the vector of dengue/ chikungunya in Kerala, India

Unused and discarded latex collection containers (LCCs) are the major breeding habitats of Aedes albopictus in the rubber plantations of Kerala, India. Platynectes sp. (Family: Dytiscidae) was observed to invade these habitats during the monsoon season and voraciously devour the larval instars of this major vector species of arbo-viral diseases. Field observations showed a reduction of 70.91% (p = 0.0017) and 100% in Aedes larval density, on the first and four days post release of eight beetles per LCC respectively. In laboratory, a beetle was found to devour 17.75 + 5.0 late larval instars of Ae. albopictus per day. Our findings indicate Platynectes sp. could be a potential bio-control agent against Ae. albopictus, the vector of chikungunya/dengue fevers, in rubber plantations.

Air quality status at selected locations in Hyderabad City.

A case study for assessing the air quality status is elaborated for Hyderabad city. Monitoring was carried out at 11 locations during March 2003. These observations on air quality status and AQEI predicts that most of the localities in Hyderabad are experiencing the air pollution stress and the trend is likely to worsen in near future if proper control measures are not implemented.

A non-radioactive method for mapping restriction fragment length polymorphic genetic markers in Anopheles gambiae.

A non-radioactive method for in situ hybridisation of Restriction Fragment Length Polymorphic (RFLP) markers to the polytene chromosome of Anopheles gambiae, the important malaria vector, which yielded good readable quality of chromosomal bands is reported. The methodology adopted was a Biotin-Streptavidin-Alkaline Phosphatase system which yielded fluorescent signals when stained with dyes such as Nitro Blue Tetrazolium and Bromo Chloro Indolyl Phosphate.

Susceptibility status of Mansonia annulifera to Brugia malayi parasites in Cherthala, Alappuzha district, Kerala.

Laboratory studies conducted on Ma. annulifera collected from Cherthala region, Kerala, endemic for Brugian filariasis indicated that this species is highly susceptible to B. malayi parasites. The experimental infection index of this species was relatively higher (2.74). No significant loss of larvae during development was recorded. The extrinsic incubation period was estimated to be 8 days.

Efficacy of diethylcarbamazine-medicated salt for microfilaraemia of Brugia malayi.

BACKGROUND: Pilot studies in India and abroad have demonstrated the benefit of cooking salt fortified with diethylcarbamazine citrate (DEC) for the control of lymphatic filariasis. In India, DEC-medicated salt has been introduced on a commercial basis in the Cherthala region of Kerala, which is endemic for Brugia malayi (B. malayi). We studied the efficacy of DEC-medicated salt in the clearance of microfilaraemia of B. malayi. METHODS: Eighteen cases of microfilaraemia (11 men; 7 women) were selected; 14 in the experimental group (i.e. treated with 0.2% w/w DEC-medicated salt) and the rest as the control group who were given a placebo. The consumption of salt and the status of parasitaemia were monitored till all the microfilaria carriers became negative. RESULTS: There was a significant reduction in the density of microfilariae (intensity) among the treated individuals over a period of time. The duration required for the clearance of microfilariae ranged from 9 to 30 [mean (SD) 19.4 (1.7)] weeks. All microfilaraemics except one reported side-effects which were mild-to-moderate and persisted for a maximum period of one month. CONCLUSION: DEC-medicated salt effectively clears microfilariae within 30 weeks in parasitaemic individuals. No 'endemic normals' reported any side-effects, though these were common among the microfilaria carriers.

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.

The resting and house frequenting behavior of Mansonia annulifera, Ma. uniformis and Ma. indiana, the vectors of Malayan filariasis in Kerala State, India.

Mansonia annulifera, was recorded to be an endophilic species, preferring to rest indoors, while Ma. uniformis was exophilic, having a predilection for outdoor resting habitats, eg bushes and shrubs. Ma. indiana did not show a clear preference to either of these biotopes. In indoor resting collections, the unfed proportion of Ma. uniformis was significantly higher during post-dusk compared to day hours (p < 0.05), indicating that this exophilic species enters houses during dusk hours for feeding. The full fed proportion was higher during day hours compared to dusk/night hours. The semigravid proportion showed a significant reduction during post-dusk hours (p < 0.05). These findings suggest that after having a blood-meal this species rest indoors and leave the houses for outdoor resting sites during the dusk hours on the subsequent night.

Seasonal abundance & biting behaviour of Mansonia annulifera, M. uniformis & M. indiana & their relative role in the transmission of malayan filariasis in Shertallai (Kerala state).

Three species of Mansonia (Mansonioides) mosquitoes, viz., Mansonia annulifera, M. uniformis and M. indiana were recorded in the Shertallai region of Kerala state. M. annulifera and M. uniformis were recorded throughout the year while M. indiana was seasonal and in small numbers. Their indoor resting density was 3.29, 0.25 and 0.10 per man per h and the man biting density was 24.67, 12.74 and 0.47 per man per night respectively. Vector density fluctuated through seasons and reached a peak during the monsoon/post-monsoon period when there was an increase in the breeding surface area and a relatively higher survival of the adults. The biting tendency of M. annulifera and M. indiana was relatively more indoors (endophagic) whereas it was outdoors (exophagic) for M. uniformis. All these mosquitoes showed a predilection towards cattle, with varying degrees of zoophily. The relative abundance, man biting behaviour and a higher transmission potential indicate that M. annulifera is a more potent vector of Brugia malayi, than M. uniformis in this region.

Primary carcinoma of vagina with uterine prolapse.

Eleven cases of primary carcinoma of vagina were admitted in Kasturba Medical College Hospital during the last 10 years, of which 6 cases aged 44-72 years, were associated with 3rd degree uterine prolapse. All the patients attended the hospital in late stage in spite of having 3rd degree uterine prolapse. Blood stained discharge and ulceration on the prolapsed part, irreducible prolapse with urinary retention and marked oedema of local and surrounding tissues were the presenting symptoms. Lesion on the vagina varied in size from 5 cm to 15 cm. IVP in both the cases of irreducible prolapse and retention of urine revealed hydroureter and hydronephrosis bilaterally. X-ray chest revealed secondaries in one patient only. Histopathology of vaginal biopsy revealed well differentiated squamous cell carcinoma in 5 cases and undifferentiated squamous cell carcinoma in one. Since the patients were in late stage of malignancy and were inoperable, treatment with external telecobalt therapy was undertaken. One patient developed vesicovaginal fistula during the treatment period and another patient developed it at the end of telecobalt therapy.

Biting rhythm of the vectors of Malayan filariasis, Mansonia annulifera, M. uniformis & M. indiana in Shertallai (Kerala state), India.

Biting activity of Mansonioides mosquitoes through all night collections for a period of two years in Shertallai region, in south India was studied. M. annulifera bites uniformly throughout the night, with two peaks of activity, one after midnight (24.00-01.00 h) and another before dawn (04.00-05.00 h). M. uniformis was found to be predominantly dusk biting, with its peak of activity between 1800 to 1900 h. M. indiana showed two peaks of biting activity one after dusk (2000-2100 h) and another before dawn (0300-0400 h). All biting, with its peak of activity between 1800 to 1900 h. M. indiana showed two peaks of biting activity one after dusk (2000-2100 h) and another before dawn (0300-0400 h). All these species following a particular pattern of activity cycles discerned the biting rhythm of Mansonioides mosquitoes to be species-specific.