Predicting key malaria transmission factors, biting and entomological inoculation rates, using modelled soil moisture in Kenya

While malaria transmission varies seasonally, large inter‐annual heterogeneity of malaria incidence occurs. Variability in entomological parameters, biting rates and entomological inoculation rates (EIR) have been strongly associated with attack rates in children. The goal of this study was to assess the weather's impact on weekly biting and EIR in the endemic area of Kisian, Kenya. Entomological data collected by the U.S. Army from March 1986 through June 1988 at Kisian, Kenya was analysed with concurrent weather data from nearby Kisumu airport. A soil moisture model of surface‐water availability was used to combine multiple weather parameters with landcover and soil features to improve disease prediction. Modelling soil moisture substantially improved prediction of biting rates compared to rainfall; soil moisture lagged two weeks explained up to 45% of An. gambiae biting variability, compared to 8% for raw precipitation. For An. funestus, soil moisture explained 32% variability, peaking after a 4‐week lag. The interspecies difference in response to soil moisture was significant (P < 0.00001). A satellite normalized differential vegetation index (NDVI) of the study site yielded a similar correlation (r2= 0.42 An. gambiae). Modelled soil moisture accounted for up to 56% variability of An. gambiae EIR, peaking at a lag of six weeks. The relationship between temperature and An. gambiae biting rates was less robust; maximum temperature r2=−0.20, and minimum temperature r2= 0.12 after lagging one week. Benefits of hydrological modelling are compared to raw weather parameters and to satellite NDVI. These findings can improve both current malaria risk assessments and those based on El Niño forecasts or global climate change model projections.

[1]  J. Patz,et al.  Global climate change and emerging infectious diseases. , 1996, JAMA.

[2]  M. Spanner,et al.  Assessment of a remote sensing-based model for predicting malaria transmission risk in villages of Chiapas, Mexico. , 1997, The American journal of tropical medicine and hygiene.

[3]  D J Bradley,et al.  Human tropical diseases in a changing environment. , 1993, Ciba Foundation symposium.

[4]  J. Stone Climate change 1995: The science of climate change. Contribution of working group I to the second assessment report of the intergovernmental panel on climate change , 1997 .

[5]  M. Blumthaler,et al.  Health and climate change , 1994, The Lancet.

[6]  M. Bouma,et al.  Epidemic malaria in India and the El Niño Southern Oscillation , 1994, The Lancet.

[7]  K.,et al.  Potential effect of global warming on mosquito-borne arboviruses. , 1994, Journal of medical entomology.

[8]  J J Picq,et al.  [Epidemiology of malaria]. , 1983, Soins. Pathologie tropicale.

[9]  David W. Scott The New S Language , 1990 .

[10]  J. Beier,et al.  Species composition of the Anopheles gambiae complex (diptera: Culicidae) at two sites in western Kenya. , 1991, Journal of medical entomology.

[11]  T Freeman,et al.  Temperature is predictive of severe malaria years in Zimbabwe. , 1996, Transactions of the Royal Society of Tropical Medicine and Hygiene.

[12]  J Rotmans,et al.  Potential impact of global climate change on malaria risk. , 1995, Environmental health perspectives.

[13]  David R. Maidment,et al.  Handbook of Hydrology , 1993 .

[14]  P. V. Perkins,et al.  Plasmodium falciparum incidence relative to entomologic inoculation rates at a site proposed for testing malaria vaccines in western Kenya. , 1994, The American journal of tropical medicine and hygiene.

[15]  A. Knudsen,et al.  Vector-borne disease problems in rapid urbanization: new approaches to vector control. , 1992, Bulletin of the World Health Organization.

[16]  P. Alonso,et al.  Vaccination with SPf66, a chemically synthesised vaccine, against Plasmodium falciparum malaria in Colombia , 1993, The Lancet.

[17]  S. Swaroop. Forecasting of epidemic malaria in the Punjab, India. , 1949, The American journal of tropical medicine and hygiene.

[18]  M. Tanner,et al.  Randomised trial of efficacy of SPf66 vaccine against Plasmodium falciparum malaria in children in southern Tanzania , 1994, The Lancet.

[19]  S I Hay,et al.  Remotely sensed surrogates of meteorological data for the study of the distribution and abundance of arthropod vectors of disease. , 1996, Annals of tropical medicine and parasitology.

[20]  J. Beier,et al.  The impact of variations in temperature on early Plasmodium falciparum development in Anopheles stephensi , 1995, Parasitology.

[21]  A. A. Buck,et al.  Bancroftian filariasis distribution and diurnal temperature differences in the southern Nile delta. , 1996, Emerging infectious diseases.

[22]  W. Takken,et al.  Model Simulations To Estimate Malaria Risk Under Climate Change , 1996 .

[23]  P. H. Martin,et al.  Malaria and climate: sensitivity of malaria potential transmission to climate , 1995 .

[24]  P. V. Perkins,et al.  Characterization of malaria transmission by Anopheles (Diptera: Culicidae) in western Kenya in preparation for malaria vaccine trials. , 1990, Journal of medical entomology.

[25]  W. Reisen,et al.  Estimates of malaria vectorial capacity for Anopheles culicifacies and Anopheles stephensi in rural Punjab province Pakistan. , 1982, Journal of medical entomology.

[26]  Simon I. Hay,et al.  The impact of remote sensing on the study and control of invertebrate intermediate hosts and vectors for disease , 1997 .

[27]  R. N. Davidson,et al.  Bruce-Chwatt's essential malariology, 3rd edition, Gilles HM, Warrell DA. Edward Arnold, Cambridge (1994), 340, 0-340-571-X , 1995 .

[28]  P. Garnham The incidence of malaria at high altitudes. , 1948, Journal. National Malaria Society.

[29]  D. Yates WatBal: an integrated water balance model for climate impact assessment of river basin runoff , 1996 .

[30]  R. Sutherst,et al.  Malaria transmission and climate change in Australia , 1996, The Medical journal of Australia.

[31]  S. Swaroop.,et al.  The Forecasting of Epidemic Malaria in the Punjab. , 1944 .

[32]  S. Hay,et al.  From predicting mosquito habitat to malaria seasons using remotely sensed data: practice, problems and perspectives. , 1998, Parasitology today.

[33]  R K Washino,et al.  Application of remote sensing to arthropod vector surveillance and control. , 1994, The American journal of tropical medicine and hygiene.

[34]  C. Ropelewski,et al.  Global and Regional Scale Precipitation Patterns Associated with the El Niño/Southern Oscillation , 1987 .

[35]  H. Briegel,et al.  Relationship between protein and proteolytic activity in the midgut of mosquitoes. , 1975, Journal of insect physiology.

[36]  S. Lindsay,et al.  Climate change and malaria transmission. , 1996, Annals of tropical medicine and parasitology.

[37]  C. Rogier,et al.  High annual and seasonal variations in malaria transmission by anophelines and vector species composition in Dielmo, a holoendemic area in Senegal. , 1997, The American journal of tropical medicine and hygiene.

[38]  Alain Villemeur,et al.  Methods and techniques , 1992 .

[39]  M. Loevinsohn,et al.  Climatic warming and increased malaria incidence in Rwanda , 1994, The Lancet.

[40]  S. Hay,et al.  Predicting malaria seasons in Kenya using multitemporal meteorological satellite sensor data. , 1998, Transactions of the Royal Society of Tropical Medicine and Hygiene.

[41]  Y. Matsuoka,et al.  AN ESTIMATION OF CLIMATIC CHANGE EFFECTS ON MALARIA , 1995 .

[42]  M. Bouma,et al.  Climate change and periodic epidemic malaria , 1994, The Lancet.

[43]  J. Cox,et al.  Predicting high‐risk years for malaria in Colombia using parameters of El Niño Southern Oscillation , 1997, Tropical medicine & international health : TM & IH.

[44]  C. Garrett-Jones,et al.  Prognosis for Interruption of Malaria Transmission Through Assessment of the Mosquito's Vectorial Capacity , 1964, Nature.

[45]  P. V. Perkins,et al.  Field evaluation of an enzyme-linked immunosorbent assay (ELISA) for Plasmodium falciparum sporozoite detection in anopheline mosquitoes from Kenya. , 1987, The American journal of tropical medicine and hygiene.

[46]  M. Thomson,et al.  Mapping malaria risk in Africa: What can satellite data contribute? , 1997, Parasitology today.

[47]  E. Rasmusson,et al.  The Relationship Between Eastern Equatorial Pacific Sea Surface Temperatures and Rainfall over India and Sri Lanka , 1983 .

[48]  D. Warrell,et al.  Bruce-Chwatt's essential malariology. , 1993 .

[49]  M. Thomson,et al.  The ecology of malaria--as seen from Earth-observation satellites. , 1996, Annals of tropical medicine and parasitology.

[50]  D. Kyle,et al.  Randomised double-blind placebo-controlled trial of SPf66 malaria vaccine in children in northwestern Thailand , 1996, The Lancet.

[51]  M. Bouma,et al.  The EI Niño Southern Oscillation and the historic malaria epidemics on the Indian subcontinent and Sri Lanka: an early warning system for future epidemics? , 1996, Tropical medicine & international health : TM & IH.

[52]  Violaine S. Mitchell,et al.  Malaria: Obstacles and Opportunities , 1991 .

[53]  David Yates,et al.  MODELING THE NILE BASIN UNDER CLIMATIC CHANGE , 1998 .

[54]  Thomas R. Karl,et al.  Trends in high-frequency climate variability in the twentieth century , 1995, Nature.