Search

Background and Objectives: Insecticide resistance in malaria vectors has been a major challenge to vector control programs and updated information to the commonly used insecticides is essential for planning appropriate vector control measures. Anopheles culicifacies and An. fluviatilis are the two main vectors prevalent in Jharkhand state of India and role of An. minimus is contemplated in the transmission of malaria in this state. All the districts in the state are predominantly inhabited by the tribal population and are endemic for malaria. A study was undertaken in 12 districts of Jharkhand state to determine the insecticide susceptibility status of the 3 prevalent primary vector species, An. culicifacies, An. fluviatilis, and An. minimus., Methods: Wild-caught adult female An. culicifacies, An. fluviatilis, and An. minimus, mosquitoes were collected from stratified ecotypes from different localities of 12 tribal districts of Jharkhand state during 2018 and 2019. Susceptibility tube tests were conducted following the WHO method using test kits. Mosquitoes were exposed to WHO impregnated papers with the prescribed discriminatory dosages of DDT - 4%, malathion - 5%, deltamethrin - 0.05%, permethrin - 0.75%, cyfluthrin - 0.15% and lambda cyhalothrin - 0.05%., Results: Results indicated that An. culicifacies has developed multiple insecticide resistance in all the 12 districts of Jharkhand state. An. fluviatilis was reported resistant for the first time to DDT in all the districts but was susceptible to malathion, deltamethrin, and permethrin whereas in one district it showed possible resistance to malathion. An. minimus was studied in Noamundi CHC of West Singhbhum district, showed possible resistance against DDT but was susceptible to malathion, deltamethrin, and permethrin., Interpretation & Conclusion: The development of multiple insecticide resistance in An. culicifacies including to pyrethroids, has been a concern for malaria control programmes for effective vector management but a report of resistance to DDT for the first time in An. fluviatlis in all the districts in the state is alarming, An. minimus was found in possible resistance category to DDT in one district and both the species were reported susceptible to malathion, deltamethrin, and permethrin. The result of the present study indicates a need for regular monitoring to assess the insecticide susceptibility to formulate effective vector control measures and resistance management., Competing Interests: None

Background & Objectives: Malaria is one of the most infectious and life-threatening vector borne disease in the tropics. Climate change can significantly influence malaria epidemiology and expansion of malaria vectors to hilly regions of Himachal Pradesh in India, hitherto considered areas of low transmission. Entomological surveillance in Kangra district of Himachal Pradesh revealed high density of a proven efficient vector of malaria, Anopheles fluviatilis, but transmission intensity of malaria was found very low. It was therefore considered prudent to investigate the sibling-species composition of An. fluviatilis complex in Kangra valley to ascertain their role in transmission of malaria., Methods: The study was undertaken in six villages in Kangra district of Himachal Pradesh, India. A total of 4446 mosquitoes were collected during the one-year study period (2018) and processed in pools of ten for molecular characterization. DNA extraction and multiplex PCR was performed on 900 An. fluviatilis mosquitoes for differentiation of sibling-species. ELISA was used to detect Plasmodium falciparum and Plasmodium vivax circumsporozoite proteins in 3790 An. fluviatilis samples., Results: Among prevalent mosquito species, An. fluviatilis was the predominant species constituting 69.5% of total mosquito collection. Sibling-species U was found in 92.22% and species T in 7.78% samples assayed. ELISA confirmed the absence of evidence of malaria parasite in any of the An. fluviatilis mosquitoes screened. Based on the difference in the sequences of conserved regions of the 28SrDNA, sibling-species U was confirmed as prevalent in the study villages., Interpretation & Conclusion: Study revealed that in Kangra district, An. fluviatilis sibling-species U is predominant followed by species T, and both are non-vectors. The absence of malaria parasite and zoophagic nature of An. fluviatilis established through blood meal analysis, confirmed that both U and T are non-vector sibling-species., Competing Interests: None

Competing Interests: None

In areas of the world where malaria prevails under unstable conditions, attacking the adult vector population through insecticide-based Indoor Residual Spraying (IRS) is the most common method for controlling epidemics. Defined in policy guidance, the use of Annual Parasitic Incidence (API) is an important tool for assessing the effectiveness of control and for planning new interventions. To investigate the consequences that a policy based on API in previous seasons might have on the population dynamics of the disease and on control itself in regions of low and seasonal transmission, we formulate a mathematical malaria model that couples epidemiologic and vector dynamics with IRS intervention. This model is parameterized for a low transmission and semi-arid region in northwest India, where epidemics are driven by high rainfall variability. We show that this type of feedback mechanism in control strategies can generate transient cycles in malaria even in the absence of environmental variability, and that this tendency to cycle can in turn limit the effectiveness of control in the presence of such variability. Specifically, for realistic rainfall conditions and over a range of control intensities, the effectiveness of such 'reactive' intervention is compared to that of an alternative strategy based on rainfall and therefore vector variability. Results show that the efficacy of intervention is strongly influenced by rainfall variability and the type of policy implemented. In particular, under an API 'reactive' policy, high vector populations can coincide more frequently with low control coverage, and in so doing generate large unexpected epidemics and decrease the likelihood of elimination. These results highlight the importance of incorporating information on climate variability, rather than previous incidence, in planning IRS interventions in regions of unstable malaria. These findings are discussed in the more general context of elimination and other low transmission regions such as highlands., (Copyright © 2013. Published by Elsevier B.V.)

Anopheles annularis is widely distributed mosquito species all over the country. An. annularis has been incriminated as a malaria vector in India, Sri Lanka, Bangladesh, Myanmar, Indonesia, Malaysia and China. In India, it has been reported to play an important role in malaria transmission as a secondary vector in certain parts of Assam, West Bengal and U.P. In Odisha and some neighbouring countries such as Sri Lanka, Nepal and Myanmar it has been recognised as a primary vector of malaria. This is a species complex of two sibling species A and B but the role of these sibling species in malaria transmission is not clearly known. An. annularis is resistant to DDT and dieldrin/HCH and susceptible to malathion and synthetic pyrethorides in most of the parts of India. In view of rapid change in ecological conditions, further studies are required on the bionomics of An. annularis and its role in malaria transmission in other parts of the country. Considering the importance of An. annularis as a malaria vector, the bionomics and its role in malaria transmission has been reviewed in this paper. In this communication, an attempt has been made to review its bionomics and its role as malaria vector. An. annularis is a competent vector of malaria, thus, due attention should be paid for its control under the vector control programmes specially in border states where it is playing a primary role in malaria transmission.

The study was carried out for evaluation of various activities of malaria control programme in five different tribal and malaria endemic Primary Health Centres of Dumka district (Jharkhand) during 2007-08. A total of 321 houses of 18 villages were surveyed on use of indoor residual spray (IRS) and insecticide-treated bed nets (ITN) and other activities as tool for vector control and interrupting the transmission of malaria. Out of 690 living rooms and 343 verandahs examined, IRS with Dichlorodiphenyl-trichloro-ethane (DDT) was done only in 16.23% living rooms and 64.72% verandahs. Refusal rate of IRS in living rooms was 81.93% due to lack of knowledge regarding the importance of IRS, no prior information to villagers, houses locked, reluctance to remove domestic articles, dislike of smell of DDT spray. Compliance rate of ITN uses was 71.66% during the night, which might be a factor for decline in malaria cases in the study area. Various important components of the programme, viz. surveillance and compliance to treatment activities, use of rapid diagnostic test kits (RDKs), involvement of accredited social health activist (ASHA's) and fever treatment depots (FTDs), laboratory activities, adult mosquito collection, other activities like constitution of village health sanitation committee, information education and communication activities, capacity building, use of larvivorous fishes, supervision of IRS etc. require much strengthening. However, 100% community acceptance was recorded for ITN in the villages surveyed. In addition, an entomological study was carried out for information on prevalence of mosquito species in this area to find out effectiveness of IRS activities. Eleven anopheline species, including three malaria vectors i.e., An. culicifacies, An. stephensi, An. fluviatilis, An. annularis, An. subpictus, An. nigerrimus, An. pallidus, An. aconitus, An. vagus, An. jamsii and An. splendidus were collected from cattle and human dwellings.

India has reasons to be concerned about climate change. Over 650 million people depend on climate-sensitive sectors, such as rain-fed agriculture and forestry, for livelihood and over 973 million people are exposed to vector borne malarial parasites. Projection of climatic factors indicates a wider exposure to malaria for the Indian population in the future. If precautionary measures are not taken and development processes are not managed properly some developmental activities, such as hydro-electric dams and irrigation canal systems, may also exacerbate breeding grounds for malaria. This article integrates climate change and developmental variables in articulating a framework for integrated impact assessment and adaptation responses, with malaria incidence in India as a case study. The climate change variables include temperature, rainfall, humidity, extreme events, and other secondary variables. Development variables are income levels, institutional mechanisms to implement preventive measures, infrastructure development that could promote malarial breeding grounds, and other policies. The case study indicates that sustainable development variables may sometimes reduce the adverse impacts on the system due to climate change alone, while it may sometimes also exacerbate these impacts if the development variables are not managed well and therefore they produce a negative impact on the system. The study concludes that well crafted and well managed developmental policies could result in enhanced resilience of communities and systems, and lower health impacts due to climate change.

A feasibility study to identify mosquitogenic conditions in six study sites in and around Delhi (Bhalaswa lake, Nazafgarh drain, Seelampur lake, Sanjay lake, Okhla barrage and Hindon barrage) using Indian Remote Sensing Satellites was carried out. The water bodies with marshy areas, vegetation and human settlements were considered as environmental variables responsible for mosquitogenic conditions. Multidate IRS 1A and B, LISS-II satellite data were collected and analysed on Vax 11/780 computers. False colour composite (FCC) images were generated and land cover assessed using supervised classification based on ground truth training sets. Ground truth validation of satellite data was done on satellite pass dates. Concurrent monitoring of larval and adult mosquito density was performed by selecting sub-sites in each study site. The results indicate that mosquitogenic conditions can be identified (with limitation of resolution, i.e. 36.5 m) using FCC images and these images can be used as base maps of study sites. Characterization of study sites based on land cover was done from the view point of mosquitogenic conditions. Spatial changes in mosquito density vis-a-vis changes in environmental variables revealed positive correlation with water bodies and vegetation in some study sites.

Resistance to chloroquine (CQ) in Plasmodium falciparum is one of the main causes of the wide-spread resurgence of malaria in India and a challenge to the effective control of the disease. In the pilgrim centre of Rameswaram Island, malaria has persisted despite the various control measures undertaken over the years. When CQ resistance in Rameswaram was investigated in vivo, recrudescent parasitaemias were observed in 25 (58%) of the 43 study subjects who were given CQ and completed follow-up, all occurring between days 10 and 28 (late treatment failures). The results of the msp1, msp2 and glurp genotyping of paired samples of P. falciparum, collected on day 0 and the day of recrudescence from 23 of the apparent treatment failures, indicated that 21 (91%) of the 23 were probably true treatment failures. All of the paired samples harboured parasites with the K76T mutation in their pfcrt genes, and subsequent sequencing of nine day-0 samples revealed the SVMNT haplotype in all nine. This is the first report of in-vivo drug resistance in P. falciparum from Rameswaram Island. Such resistance, which is probably the result of the indiscriminate use of CQ and/or the import of malaria from mainland India, warrants a change in the drug regimen used locally for the first-line treatment of uncomplicated, P. falciparum malaria, to make treatment more effective and slow the development and spread of more foci of CQ resistance. [ABSTRACT FROM AUTHOR]