Effect of construction of an irrigation canal on malaria situation in two primary health centres of Dhenkanal district of Orissa, India.

To assess the impact of irrigation canals on malaria transmission, a study was conducted in Dhenkanal district of Orissa, India. The district is situated in the central part of Orissa and hyperendemic area for malaria. A canal system is being constructed for irrigation in the district, which passes through Parjang and Analabereni Primary Health Centres (PHC), endemic for malaria. The water has been released only up to Parjang (Canal with water -CWW) area during the end of 2004 and construction work is still going on in Analabereni PHC (Canal under construction-CUC). Retrospective clinical data (2001-2008) collected from health services from two study sites showed average Slide Positivity Rate (SPR) before release of water (2001-2004) was 9.25% and 18.04% in CWW and CUC areas, respectively. After release of water (2005-2008) the SPR was 5.77% and 10.19%, in CWW and CUC areas, respectively. The average Annual Parasite Incidence (API) was 7.66 and 22.67 in CWW and CUC areas before the release of water and 5.32 and 12.28 after release of water, respectively. A point fever survey was conducted in 2009 which revealed the presence of Plasmodium falciparum (Pf) and P. vivax (Pv) in both study areas. The survey found SPR of 18.82% and 24.54%, and Pf percentages of 75% and 85%, in CWW and CUC areas, respectively. The present study revealed the presence of two malaria vectors, Anopheles culicifacies and Anopheles annularis in the area. Vector Per Man Hour Density was 2.38 in CWW and 2.69 in CUC for An. culicifacies and 1.46 and 1.54 for An. annularis respectively. The sporozoites rates were found to be 3.6 and 3.8 for CWW and CUC, respectively. The present study reveals that, the construction of canal system did not increase the malaria prevalence during post water release period - implying that the malaria control programme was effective although still more intensive situation specific vectors control programme need to be continued simultaneously so that malaria transmission can be curtailed.

Rapid spread of chikungunya virus infection in Orissa: India.

BACKGROUND & OBJECTIVES: A large number of cases of undiagnosed fever and joint pain were reported from different parts of the State of Orissa since February 2006. Epidemiological and laboratory investigation were carried out to confirm the cause of emerging illness, which was provisionally suspected as Chikungunya (CHIK) fever. METHODS: Upon getting the reports of suspected CHIK like illness in different parts of the State, epidemic investigations were carried out in the outbreak affected villages. Case history was recorded, clinical examination undertaken and blood samples collected for seroconfirmation for CHIK IgM antibody using ELISA based kit. Simultaneously vector survey was also carried out. RESULTS: With no previous record of CHIK infection in the State, the first outbreak was confirmed during February 2006. Subsequently, the infection spread to 13 of 30 districts in different episodes covering 79 villages till November 2007. Attack rate was 9-43 per cent in the different outbreaks with average seropositivity of 24 per cent to CHIK specific IgM. Morbidity was high though no deaths were recorded. Aedes aegypti and Ae. albopictus were identified as the possible vectors for transmission. INTERPRETATION & CONCLUSIONS: The report confirmed emergence of CHIK infection in the State of Orissa, India, and its spread to a larger geographic zone in a short period which warrants public health measures to control further spread.

The development and evaluation of a single step multiplex PCR for simultaneous detection of Anopheles annularis group mosquitoes, human host preference and Plasmodium falciparum sporozoite presence.

The Anopheles annularis group mosquitoes, subgenus Cellia Theobald (Diptera: Culicidae), includes five recognized species: An. annularis Van der Wulp, An. nivipes Theobald, An. pallidus Theobald, An. philippinensis Ludlow and An. schueffneri Stanton. From these five, the three most common species found in Orissa were considered for this study because of their remarkable vectorial and behavioral variation and the important role they play in malaria transmission. To identify and understand their role in malaria transmission we developed a single multiplex PCR-based assay. This assay included the detection of human blood feeding habit and Plasmodium falciparum sporozoite presence. Of the 186 An. annularis mosquitoes collected, morphological character-based identification showed that 94 were An. annularis, 54 were An. philippinensis and 38 were An. pallidus. However, the multiplex PCR assay confirmed that 91 were An. annularis, 56 were An. philippinensis and 39 were An. pallidus individuals after adjustments were made for misidentified specimens in the morphological method. Anopheles annularis and An. philippinensis were found positive for human blood, and two samples of An. annularis species were positive for P. falciparum sporozoites. This one-step PCR-based method constitutes a very powerful tool in large surveys of anopheline populations.