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Sardar AA, Chatterjee M, Jana K, Saha P, Maji AK, Guha SK, Kundu PK. Seasonal variation of sand fly populations in Kala-azar endemic areas of the Malda district, West Bengal, India. Acta Trop 2020; 204:105358. [PMID: 31987778 DOI: 10.1016/j.actatropica.2020.105358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 01/06/2020] [Accepted: 01/23/2020] [Indexed: 01/19/2023]
Abstract
Vector control is one of the main aspects to reach the target of eliminating visceral leishmaniasis from Indian sub-continent as set by the World Health Organisation. Data on different aspects of vector like ecology, behaviour, population dynamics and their association with environmental factors are very important for formulating an effective vector control strategy. The present work was designed to study the species abundance and impact of environmental factors on population dynamics of vector P. argentipes in a visceral leishmaniasis endemic area of Malda district, West Bengal. Adult sand flies were collected using light traps and mouth aspirators from twelve kala-azar affected villages of Habibpur block of Malda district, on a monthly basis from January to December, 2018. Morphological and molecular methods were used for species identification. Population dynamics were assessed by man hour density and per night per trap collection. Data were analysed using SPSS software to determine the impact of environmental factors on vector population P. argentipes was found to the predominant species and prevalent throughout the year. A significantly higher number of sand flies were collected from cattle sheds than human dwellings and peri-domestic vegetation. A portion of the P. argentipes population was exophilic and exophagic as evidenced by their collection from peri-domestic vegetation. The highest population density was recorded during April to September. Population dynamics were mostly influenced by average temperature along humidity and rain fall. Resting behaviour of sand flies was not restricted to the lower portion of the wall but equally distributed throughout the wall and ceiling. Programme officials should consider management of outdoor populations of the sand flies and timings of indoor residual spray for chemical control purpose.
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Affiliation(s)
- Ashif Ali Sardar
- Department of Microbiology, Calcutta School of Tropical Medicine, Kolkata, West Bengal, India.
| | - Moytrey Chatterjee
- Department of Microbiology, Calcutta School of Tropical Medicine, Kolkata, West Bengal, India.
| | - Kingsuk Jana
- Department of Microbiology, Calcutta School of Tropical Medicine, Kolkata, West Bengal, India.
| | - Pabitra Saha
- Department of Microbiology, Calcutta School of Tropical Medicine, Kolkata, West Bengal, India; Department of Zoology, A. P. C. Roy Govt. College, Himachal Bihar, Matigara, Siliguri, West Bengal, India.
| | - Ardhendu Kumar Maji
- Department of Microbiology, Calcutta School of Tropical Medicine, Kolkata, West Bengal, India.
| | - Subhasish Kamal Guha
- Department of Tropical Medicine, Calcutta School of Tropical Medicine, Kolkata, West Bengal, India.
| | - Pratip Kumar Kundu
- Department of Microbiology, Calcutta School of Tropical Medicine, Kolkata, West Bengal, India.
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Thomas S, Ravishankaran S, Justin NAJA, Asokan A, Kalsingh TMJ, Mathai MT, Valecha N, Montgomery J, Thomas MB, Eapen A. Microclimate variables of the ambient environment deliver the actual estimates of the extrinsic incubation period of Plasmodium vivax and Plasmodium falciparum: a study from a malaria-endemic urban setting, Chennai in India. Malar J 2018; 17:201. [PMID: 29769075 PMCID: PMC5956829 DOI: 10.1186/s12936-018-2342-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 05/07/2018] [Indexed: 01/07/2023] Open
Abstract
Background Environmental factors such as temperature, relative humidity and their daily variation influence a range of mosquito life history traits and hence, malaria transmission. The standard way of characterizing environmental factors with meteorological station data need not be the actual microclimates experienced by mosquitoes within local transmission settings. Methods A year-long study was conducted in Chennai, India to characterize local temperature and relative humidity (RH). Data loggers (Hobos) were placed in a range of probable indoor and outdoor resting sites of Anopheles stephensi. Recordings were taken hourly to estimate mean temperature and RH, together with daily temperature range (DTR) and daily relative humidity range. The temperature data were used to explore the predicted variation in extrinsic incubation period (EIP) of Plasmodium falciparum and Plasmodium vivax between microhabitats and across the year. Results Mean daily temperatures within the indoor settings were significantly warmer than those recorded outdoors. DTR in indoor environments was observed to be modest and ranged from 2 to 6 °C. Differences in EIP between microhabitats were most notable during the hottest summer months of April–June, with parasite development predicted to be impaired for tiled houses and overhead tanks. Overall, the prevailing warm and stable conditions suggest rapid parasite development rate regardless of where mosquitoes might rest. Taking account of seasonal and local environmental variation, the predicted EIP of P. falciparum varied from a minimum of 9.1 days to a maximum of 15.3 days, while the EIP of P. vivax varied from 8.0 to 24.3 days. Conclusions This study provides a detailed picture of the actual microclimates experienced by mosquitoes in an urban slum malaria setting. The data indicate differences between microhabitats that could impact mosquito and parasite life history traits. The predicted effects for EIP are often relatively subtle, but variation between minimum and maximum EIPs can play a role in disease transmission, depending on the time of year and where mosquitoes rest. Appropriate characterization of the local microclimate conditions would be the key to fully understand the effects of environment on local transmission ecology. Electronic supplementary material The online version of this article (10.1186/s12936-018-2342-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shalu Thomas
- ICMR-National Institute of Malaria Research, IDVC Field Unit, NIE Campus, 2nd Main Road, TNHB, Ayapakkam, Chennai, 600 077, India.,Department of Zoology, Madras Christian College, Tambaram, Chennai, 600 059, India
| | - Sangamithra Ravishankaran
- ICMR-National Institute of Malaria Research, IDVC Field Unit, NIE Campus, 2nd Main Road, TNHB, Ayapakkam, Chennai, 600 077, India
| | - N A Johnson Amala Justin
- ICMR-National Institute of Malaria Research, IDVC Field Unit, NIE Campus, 2nd Main Road, TNHB, Ayapakkam, Chennai, 600 077, India
| | - Aswin Asokan
- ICMR-National Institute of Malaria Research, IDVC Field Unit, NIE Campus, 2nd Main Road, TNHB, Ayapakkam, Chennai, 600 077, India
| | - T Maria Jusler Kalsingh
- ICMR-National Institute of Malaria Research, IDVC Field Unit, NIE Campus, 2nd Main Road, TNHB, Ayapakkam, Chennai, 600 077, India
| | - Manu Thomas Mathai
- Department of Zoology, Madras Christian College, Tambaram, Chennai, 600 059, India
| | - Neena Valecha
- ICMR-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, 110 077, India
| | - Jacqui Montgomery
- Department of Entomology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Matthew B Thomas
- Department of Entomology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Alex Eapen
- ICMR-National Institute of Malaria Research, IDVC Field Unit, NIE Campus, 2nd Main Road, TNHB, Ayapakkam, Chennai, 600 077, India.
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