Factors associated with high heterogeneity of malaria at fine spatial scale in the Western Kenyan highlands

Amrish Y. Baidjoe; Jennifer Stevenson; Philip Knight; William Stone; Gillian Stresman; Victor Osoti; Euniah Makori; Chrispin Owaga; Wycliffe Odongo; Pauline China; Shehu Shagari; Simon Kariuki; Chris Drakeley; Jonathan Cox; Teun Bousema

doi:10.1186/s12936-016-1362-y

Factors associated with high heterogeneity of malaria at fine spatial scale in the Western Kenyan highlands

Amrish Y. Baidjoe, Jennifer Stevenson, Philip Knight, William Stone, Gillian Stresman, Victor Osoti, Euniah Makori, Chrispin Owaga, Wycliffe Odongo, Pauline China, Shehu Shagari, Simon Kariuki, Chris Drakeley, Jonathan Cox, Teun Bousema

Bloomberg School of Public Health

Research output: Contribution to journal › Article › peer-review

23 Scopus citations

Abstract

Background: The East African highlands are fringe regions between stable and unstable malaria transmission. What factors contribute to the heterogeneity of malaria exposure on different spatial scales within larger foci has not been extensively studied. In a comprehensive, community-based cross-sectional survey an attempt was made to identify factors that drive the macro- and micro epidemiology of malaria in a fringe region using parasitological and serological outcomes. Methods: A large cross-sectional survey including 17,503 individuals was conducted across all age groups in a 100 km² area in the Western Kenyan highlands of Rachuonyo South district. Households were geo-located and prevalence of malaria parasites and malaria-specific antibodies were determined by PCR and ELISA. Household and individual risk-factors were recorded. Geographical characteristics of the study area were digitally derived using high-resolution satellite images. Results: Malaria antibody prevalence strongly related to altitude (1350-1600 m, p < 0.001). A strong negative association with increasing altitude and PCR parasite prevalence was found. Parasite carriage was detected at all altitudes and in all age groups; 93.2 % (2481/2663) of malaria infections were apparently asymptomatic. Malaria parasite prevalence was associated with age, bed net use, house construction features, altitude and topographical wetness index. Antibody prevalence was associated with all these factors and distance to the nearest water body. Conclusion: Altitude was a major driver of malaria transmission in this study area, even across narrow altitude bands. The large proportion of asymptomatic parasite carriers at all altitudes and the age-dependent acquisition of malaria antibodies indicate stable malaria transmission; the strong correlation between current parasite carriage and serological markers of malaria exposure indicate temporal stability of spatially heterogeneous transmission.

Original language	English (US)
Article number	307
Journal	Malaria journal
Volume	15
Issue number	1
DOIs	https://doi.org/10.1186/s12936-016-1362-y
State	Published - Jun 4 2016

Keywords

Elimination
Heterogeneity
Hotspots
Malaria
Plasmodium falciparum
Polymerase chain reaction
Risk-factors
Serology
Transmission

ASJC Scopus subject areas

Parasitology
Infectious Diseases

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10.1186/s12936-016-1362-y

Cite this

Baidjoe, A. Y., Stevenson, J., Knight, P., Stone, W., Stresman, G., Osoti, V., Makori, E., Owaga, C., Odongo, W., China, P., Shagari, S., Kariuki, S., Drakeley, C., Cox, J., & Bousema, T. (2016). Factors associated with high heterogeneity of malaria at fine spatial scale in the Western Kenyan highlands. Malaria journal, 15(1), Article 307. https://doi.org/10.1186/s12936-016-1362-y

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title = "Factors associated with high heterogeneity of malaria at fine spatial scale in the Western Kenyan highlands",

abstract = "Background: The East African highlands are fringe regions between stable and unstable malaria transmission. What factors contribute to the heterogeneity of malaria exposure on different spatial scales within larger foci has not been extensively studied. In a comprehensive, community-based cross-sectional survey an attempt was made to identify factors that drive the macro- and micro epidemiology of malaria in a fringe region using parasitological and serological outcomes. Methods: A large cross-sectional survey including 17,503 individuals was conducted across all age groups in a 100 km2 area in the Western Kenyan highlands of Rachuonyo South district. Households were geo-located and prevalence of malaria parasites and malaria-specific antibodies were determined by PCR and ELISA. Household and individual risk-factors were recorded. Geographical characteristics of the study area were digitally derived using high-resolution satellite images. Results: Malaria antibody prevalence strongly related to altitude (1350-1600 m, p < 0.001). A strong negative association with increasing altitude and PCR parasite prevalence was found. Parasite carriage was detected at all altitudes and in all age groups; 93.2 % (2481/2663) of malaria infections were apparently asymptomatic. Malaria parasite prevalence was associated with age, bed net use, house construction features, altitude and topographical wetness index. Antibody prevalence was associated with all these factors and distance to the nearest water body. Conclusion: Altitude was a major driver of malaria transmission in this study area, even across narrow altitude bands. The large proportion of asymptomatic parasite carriers at all altitudes and the age-dependent acquisition of malaria antibodies indicate stable malaria transmission; the strong correlation between current parasite carriage and serological markers of malaria exposure indicate temporal stability of spatially heterogeneous transmission.",

keywords = "Elimination, Heterogeneity, Hotspots, Malaria, Plasmodium falciparum, Polymerase chain reaction, Risk-factors, Serology, Transmission",

author = "Baidjoe, {Amrish Y.} and Jennifer Stevenson and Philip Knight and William Stone and Gillian Stresman and Victor Osoti and Euniah Makori and Chrispin Owaga and Wycliffe Odongo and Pauline China and Shehu Shagari and Simon Kariuki and Chris Drakeley and Jonathan Cox and Teun Bousema",

note = "Funding Information: This work was supported by the Bill and Melinda Gates Foundation, under the Malaria Transmission Consortium, Grant No. 45114 and the Grand Challenge Grant No. OPP1024438. TB is further supported by a VIDI fellowship from the Netherlands Organization for Scientific Research (NWO; project number 016.158.306). Publisher Copyright: {\textcopyright} 2016 The Author(s).",

year = "2016",

month = jun,

day = "4",

doi = "10.1186/s12936-016-1362-y",

language = "English (US)",

volume = "15",

journal = "Malaria journal",

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publisher = "BioMed Central",

number = "1",

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T1 - Factors associated with high heterogeneity of malaria at fine spatial scale in the Western Kenyan highlands

AU - Baidjoe, Amrish Y.

AU - Stevenson, Jennifer

AU - Knight, Philip

AU - Stone, William

AU - Stresman, Gillian

AU - Osoti, Victor

AU - Makori, Euniah

AU - Owaga, Chrispin

AU - Odongo, Wycliffe

AU - China, Pauline

AU - Shagari, Shehu

AU - Kariuki, Simon

AU - Drakeley, Chris

AU - Cox, Jonathan

AU - Bousema, Teun

N1 - Funding Information: This work was supported by the Bill and Melinda Gates Foundation, under the Malaria Transmission Consortium, Grant No. 45114 and the Grand Challenge Grant No. OPP1024438. TB is further supported by a VIDI fellowship from the Netherlands Organization for Scientific Research (NWO; project number 016.158.306). Publisher Copyright: © 2016 The Author(s).

PY - 2016/6/4

Y1 - 2016/6/4

N2 - Background: The East African highlands are fringe regions between stable and unstable malaria transmission. What factors contribute to the heterogeneity of malaria exposure on different spatial scales within larger foci has not been extensively studied. In a comprehensive, community-based cross-sectional survey an attempt was made to identify factors that drive the macro- and micro epidemiology of malaria in a fringe region using parasitological and serological outcomes. Methods: A large cross-sectional survey including 17,503 individuals was conducted across all age groups in a 100 km2 area in the Western Kenyan highlands of Rachuonyo South district. Households were geo-located and prevalence of malaria parasites and malaria-specific antibodies were determined by PCR and ELISA. Household and individual risk-factors were recorded. Geographical characteristics of the study area were digitally derived using high-resolution satellite images. Results: Malaria antibody prevalence strongly related to altitude (1350-1600 m, p < 0.001). A strong negative association with increasing altitude and PCR parasite prevalence was found. Parasite carriage was detected at all altitudes and in all age groups; 93.2 % (2481/2663) of malaria infections were apparently asymptomatic. Malaria parasite prevalence was associated with age, bed net use, house construction features, altitude and topographical wetness index. Antibody prevalence was associated with all these factors and distance to the nearest water body. Conclusion: Altitude was a major driver of malaria transmission in this study area, even across narrow altitude bands. The large proportion of asymptomatic parasite carriers at all altitudes and the age-dependent acquisition of malaria antibodies indicate stable malaria transmission; the strong correlation between current parasite carriage and serological markers of malaria exposure indicate temporal stability of spatially heterogeneous transmission.

AB - Background: The East African highlands are fringe regions between stable and unstable malaria transmission. What factors contribute to the heterogeneity of malaria exposure on different spatial scales within larger foci has not been extensively studied. In a comprehensive, community-based cross-sectional survey an attempt was made to identify factors that drive the macro- and micro epidemiology of malaria in a fringe region using parasitological and serological outcomes. Methods: A large cross-sectional survey including 17,503 individuals was conducted across all age groups in a 100 km2 area in the Western Kenyan highlands of Rachuonyo South district. Households were geo-located and prevalence of malaria parasites and malaria-specific antibodies were determined by PCR and ELISA. Household and individual risk-factors were recorded. Geographical characteristics of the study area were digitally derived using high-resolution satellite images. Results: Malaria antibody prevalence strongly related to altitude (1350-1600 m, p < 0.001). A strong negative association with increasing altitude and PCR parasite prevalence was found. Parasite carriage was detected at all altitudes and in all age groups; 93.2 % (2481/2663) of malaria infections were apparently asymptomatic. Malaria parasite prevalence was associated with age, bed net use, house construction features, altitude and topographical wetness index. Antibody prevalence was associated with all these factors and distance to the nearest water body. Conclusion: Altitude was a major driver of malaria transmission in this study area, even across narrow altitude bands. The large proportion of asymptomatic parasite carriers at all altitudes and the age-dependent acquisition of malaria antibodies indicate stable malaria transmission; the strong correlation between current parasite carriage and serological markers of malaria exposure indicate temporal stability of spatially heterogeneous transmission.

KW - Elimination

KW - Heterogeneity

KW - Hotspots

KW - Malaria

KW - Plasmodium falciparum

KW - Polymerase chain reaction

KW - Risk-factors

KW - Serology

KW - Transmission

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DO - 10.1186/s12936-016-1362-y

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C2 - 27259286

AN - SCOPUS:84971663746

SN - 1475-2875

VL - 15

JO - Malaria journal

JF - Malaria journal

IS - 1

M1 - 307

ER -

Factors associated with high heterogeneity of malaria at fine spatial scale in the Western Kenyan highlands

Abstract

Keywords

ASJC Scopus subject areas

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