Climate forcing and desert malaria: the effect of irrigation

Malaria Journal - 2011
Andrés Baeza1, Menno J. Bouma2, Andy Dobson3, R. C. Dhiman4, H. C. Srivastava5, Mercedes Pascual6,1
1Deparment of Ecology and Evolutionary Biology University of Michigan, Ann Arbor, USA
2London School of Hygiene and Tropical Medicine, University of London, London, UK
3Department of Ecology and Evolutionary Biology, Princeton University, Princeton, USA
4National Institute of Malaria Research (ICMR), Delhi, India
5National Institute of Malaria Research, (ICMR), Field Unit, Civil Hospital, Nadiad, India
6Howard Hughes Medical Institute, Chevy Chase, USA

Tóm tắt

Abstract Background Rainfall variability and associated remote sensing indices for vegetation are central to the development of early warning systems for epidemic malaria in arid regions. The considerable change in land-use practices resulting from increasing irrigation in recent decades raises important questions on concomitant change in malaria dynamics and its coupling to climate forcing. Here, the consequences of irrigation level for malaria epidemics are addressed with extensive time series data for confirmed Plasmodium falciparum monthly cases, spanning over two decades for five districts in north-west India. The work specifically focuses on the response of malaria epidemics to rainfall forcing and how this response is affected by increasing irrigation. Methods and Findings Remote sensing data for the Normalized Difference Vegetation Index (NDVI) are used as an integrated measure of rainfall to examine correlation maps within the districts and at regional scales. The analyses specifically address whether irrigation has decreased the coupling between malaria incidence and climate variability, and whether this reflects (1) a breakdown of NDVI as a useful indicator of risk, (2) a weakening of rainfall forcing and a concomitant decrease in epidemic risk, or (3) an increase in the control of malaria transmission. The predictive power of NDVI is compared against that of rainfall, using simple linear models and wavelet analysis to study the association of NDVI and malaria variability in the time and in the frequency domain respectively. Conclusions The results show that irrigation dampens the influence of climate forcing on the magnitude and frequency of malaria epidemics and, therefore, reduces their predictability. At low irrigation levels, this decoupling reflects a breakdown of local but not regional NDVI as an indicator of rainfall forcing. At higher levels of irrigation, the weakened role of climate variability may be compounded by increased levels of control; nevertheless this leads to no significant decrease in the actual risk of disease. This implies that irrigation can lead to more endemic conditions for malaria, creating the potential for unexpectedly large epidemics in response to excess rainfall if these climatic events coincide with a relaxation of control over time. The implications of our findings for control policies of epidemic malaria in arid regions are discussed.

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Tài liệu tham khảo

Tyagi BK: A review of the emergence of Plasmodium falciparum-dominated malaria in irrigated areas of the Thar Desert, India. Acta Trop. 2004, 89: 227-239. 10.1016/j.actatropica.2003.09.016.

Sachs J, Malaney P: The economic and social burden of malaria. Nature. 2002, 415: 680-685. 10.1038/415680a.

Yacob KB, Swaroop S: Malaria and Rainfall in the Punjab. Journal of the Malaria Istitute of India. 1946, 6:

Christophers R: Malaria in the Punjab. Dept Gov India (New Series) no 46. Edited by: Sanit SMOM. 1911, Calcutta, India: Superintendent Government Printing

Thomson MC, Doblas-Reyes FJ, Mason SJ, Hagedorn R, Connor SJ, Phindela T, Morse AP, Palmer TN: Malaria early-warnings based on seasonal climate forecasts from multi-model ensembles. Nature. 2006, 439: 576-579. 10.1038/nature04503.

Gill CA: Malaria in the Punjab. The malaria forecast for the year 1922. Indian J Med Res. 1923, 661-666.

Swaroop S: Forecasting of epidemic malaria in the Punjab, India. Am J Trop Med Hyg. 1949, 29: 1-16.

Zurbrigg S: Re-thinking the" human factor" in malaria mortality: the case of Punjab, 1868-1940. Parassitologia. 1994, 36: 121-135.

Bouma MJ, vanderKaay HJ: The El Nino Southern Oscillation and the historic malaria epidemics on the Indian subcontinent and Sri Lanka: An early warning system for future epidemics?. Trop Med Int Health. 1996, 1: 86-96. 10.1046/j.1365-3156.1996.d01-7.x.

Akhtar R, McMichael AJ: Rainfall and malaria outbreaks in western Rajasthan. Lancet. 1996, 348: 1457-1458.

Tyagi BK, Yadav SP: Bionomics of malaria vectors in two physiographically different areas of the epidemic-prone Thar Desert, north-western Rajasthan (India). J Arid Environ. 2001, 47: 161-172. 10.1006/jare.2000.0698.

Rogers DJ, Randolph SE, Snow RW, Hay SI: Satellite imagery in the study and forecast of malaria. Nature. 2002, 415: 710-715. 10.1038/415710a.

Thomson MC, Connor SJ, D'Alessandro U, Rowlingson B, Diggle P, Cresswell M, Greenwood B: Predicting malaria infection in Gambian children from satellite data and bed net use surveys: The importance of spatial correlation in the interpretation of results. Am J Trop Med Hyg. 1999, 61: 2-8.

Hay SI, Snow RW, Rogers DJ: Predicting malaria seasons in Kenya using multitemporal meteorological satellite sensor data. Trans R Soc Trop Med Hyg. 1998, 92: 12-20. 10.1016/S0035-9203(98)90936-1.

Ceccato P, Ghebremeskel T, Jaiteh M, Graves PM, Levy M, Ghebreselassie S, Ogbamariam A, Barnston AG, Bell M, del Corral J, Connor SJ, Fesseha I, Brantly EP, Thomson MC: Malaria stratification, climate, and epidemic early warning in Eritrea. Am J Trop Med Hyg. 2007, 77: 61-68.

Connor SJ, Thomson MC, Flasse SP, Perryman AH: Environmental information systems in malaria risk mapping and epidemic forecasting. Disasters. 1998, 22: 39-56. 10.1111/1467-7717.00074.

Thomson MC, Connor SJ, Milligan P, Flasse SP: Mapping malaria risk in Africa: What can satellite data contribute?. Parasitol Today. 1997, 13: 313-318. 10.1016/S0169-4758(97)01097-1.

Tucker CJ, Pinzon JE, Brown ME, Slayback DA, Pak EW, Mahoney R, Vermote EF, El Saleous N: An extended AVHRR 8-km NDVI dataset compatible with MODIS and SPOT vegetation NDVI data. International Journal of Remote Sensing. 2005, 26: 4485-4498. 10.1080/01431160500168686.

LP DAAC: ASTER and MODIS Land Data Products and Services. [https://lpdaac.usgs.gov]

Laneri K, Bhadra A, Ionides EL, Bouma M, Dhiman RC, Yadav RS, Pascual M: Forcing versus feedback: epidemic malaria and monsoon rains in north-west India. PLos Comput Biol. 2010, 6: e1000898-10.1371/journal.pcbi.1000898.

Cazelles B, Chavez M, de Magny GC, Guegan JF, Hales S: Time-dependent spectral analysis of epidemiological time-series with wavelets. J R Soc Interface. 2007, 4: 625-636. 10.1098/rsif.2007.0212.

Pascual M, Cazelles B, Bouma MJ, Chaves LF, Koelle K: Shifting patterns: malaria dynamics and rainfall variability in an African highland. Proc R Soc B-Biol Sci. 2008, 275: 123-132. 10.1098/rspb.2007.1068.

Johansson MA, Cummings DAT, Glass GE: Multiyear climate variability and dengue-El Nino Southern Oscillation, weather, and dengue incidence in Puerto Rico, Mexico, and Thailand: A longitudinal data analysis. PLos Med. 2009, 6: e1000168-10.1371/journal.pmed.1000168.

Mukhtar M, Herrel N, Amerasinghe FP, Ensink J, van der Hoek W, Konradsen F: Role of wastewater irrigation in mosquito breeding in south Punjab, Pakistan. Southeast Asian J Trop Med Publ Health. 2003, 34: 72-82.

Kant R, Pandey SD: Breeding preferences of Anopheles culicifacies in the rice agro-ecosystem in Kheda district, Gujarat. Indian Journal of Malariology. 1999, 36: 53-60.

Ijumba JN, Lindsay SW: Impact of irrigation on malaria in Africa: paddies paradox. Med Vet Entomol. 2001, 15: 1-11. 10.1046/j.1365-2915.2001.00279.x.

Ijumba JN, Shenton FC, Clarke SE, Mosha FW, Lindsay SW: Irrigated crop production is associated with less malaria than traditional agricultural practices in Tanzania. Trans R Soc Trop Med Hyg. 2002, 96: 476-480. 10.1016/S0035-9203(02)90408-6.

Yasuoka J, Mangione TW, Spielman A, Levins R: Impact of education on knowledge, agricultural practices, and community actions for mosquito control and mosquito-borne disease prevention in rice ecosystems in Sri Lanka. Am J Trop Med Hyg. 2006, 74: 1034-1042.

Ng'ang'a PN, Jayasinghe G, Kimani V, Shililu J, Kabutha C, Kabuage L, Githure J, Mutero C: Bed net use and associated factors in a rice farming community in Central Kenya. Malar J. 2009, 8: 64-10.1186/1475-2875-8-64.

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