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Factors associated with malaria parasitemia, anemia and serological responses in a spectrum of epidemiological settings in Uganda.

Yeka A, Nankabirwa J, Mpimbaza A, Kigozi R, Arinaitwe E, Drakeley C, Greenhouse B, Kamya MR, Dorsey G, Staedke SG - PLoS ONE (2015)

Bottom Line: Prevalence of anemia (hemoglobin < 11.0 g/dL) was significantly higher in Walukuba (18.9%) and Nagongera (17.4%) than in Kihihi (13.1%), and was strongly associated with decreasing age for those ≤ 5 years at all sites.Parasite prevalence was significantly higher in Nagongera (48.3%) than in Walukuba (12.2%) and Kihihi (12.8%), and significantly increased with age to 11 years, and then significantly decreased at all sites.AMA-1 seroconversion rates strongly correlated with transmission intensity, while serological responses to MSP-119 did not.

View Article: PubMed Central - PubMed

Affiliation: Makerere University School of Public Health, College of Health Sciences, Kampala, Uganda; Infectious Diseases Research Collaboration, Kampala, Uganda.

ABSTRACT

Background: Understanding the current epidemiology of malaria and the relationship between intervention coverage, transmission intensity, and burden of disease is important to guide control activities. We aimed to determine the prevalence of anemia, parasitemia, and serological responses to P. falciparum antigens, and factors associated with these indicators, in three different epidemiological settings in Uganda.

Methods and findings: In 2012, cross-sectional surveys were conducted in 200 randomly selected households from each of three sites: Walukuba, Jinja district (peri-urban); Kihihi, Kanungu district (rural); and Nagongera, Tororo district (rural) with corresponding estimates of annual entomologic inoculation rates (aEIR) of 3.8, 26.6, and 125.0, respectively. Of 2737 participants, laboratory testing was done in 2227 (81.4%), including measurement of hemoglobin, parasitemia using microscopy, and serological responses to P. falciparum apical membrane antigen 1 (AMA-1) and merozoite surface protein 1, 19 kilodalton fragment (MSP-119). Analysis of laboratory results was restricted to 1949 (87.5%) participants aged ≤ 40 years. Prevalence of anemia (hemoglobin < 11.0 g/dL) was significantly higher in Walukuba (18.9%) and Nagongera (17.4%) than in Kihihi (13.1%), and was strongly associated with decreasing age for those ≤ 5 years at all sites. Parasite prevalence was significantly higher in Nagongera (48.3%) than in Walukuba (12.2%) and Kihihi (12.8%), and significantly increased with age to 11 years, and then significantly decreased at all sites. Seropositivity to AMA-1 was 53.3% in Walukuba, 63.0% in Kihihi, and 83.7% in Nagongera and was associated with increasing age at all sites. AMA-1 seroconversion rates strongly correlated with transmission intensity, while serological responses to MSP-119 did not.

Conclusion: Anemia was predominant in young children and parasitemia peaked by 11 years across 3 sites with varied transmission intensity. Serological responses to AMA-1 appeared to best reflect transmission intensity, and may be a more accurate indicator for malaria surveillance than anemia or parasitemia.

No MeSH data available.


Related in: MedlinePlus

Map of study sites in Uganda.
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pone.0118901.g001: Map of study sites in Uganda.

Mentions: Cross-sectional surveys were conducted between January and June 2012 in three sub-counties purposively chosen to represent varied malaria transmission settings in Uganda: Walukuba, Jinja district; Kihihi, Kanungu district; and Nagongera, Tororo district (Fig. 1). In each sub-county, entomological surveys were conducted from October 2011 – September 2012 using monthly human landing catches to generate estimates of aEIR as previously described [28]. Malaria transmission at all three sites was perennial, with 2 annual peaks following the rainy seasons. Walukuba is a peri-urban area near Lake Victoria in the south-central part of the country with an estimated aEIR of 3.8 infectious bites per person per year. Kihihi is a rural area in the south-western part of the country, with an estimated aEIR of 26.6. Nagongera is a rural area in the south-eastern part of the country near the Kenyan border, with an estimated aEIR of 125.0. Key malaria control interventions in all three districts include use of LLINs, malaria case management with ACTs, and IPTp with sulfadoxine-pyrimethamine. A single round of IRS using lambda-cyhalothrin was conducted in Kanungu district in 2007 and a mass, community-based campaign to distribute free ITNs was conducted in Tororo district in January 2011.


Factors associated with malaria parasitemia, anemia and serological responses in a spectrum of epidemiological settings in Uganda.

Yeka A, Nankabirwa J, Mpimbaza A, Kigozi R, Arinaitwe E, Drakeley C, Greenhouse B, Kamya MR, Dorsey G, Staedke SG - PLoS ONE (2015)

Map of study sites in Uganda.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4358889&req=5

pone.0118901.g001: Map of study sites in Uganda.
Mentions: Cross-sectional surveys were conducted between January and June 2012 in three sub-counties purposively chosen to represent varied malaria transmission settings in Uganda: Walukuba, Jinja district; Kihihi, Kanungu district; and Nagongera, Tororo district (Fig. 1). In each sub-county, entomological surveys were conducted from October 2011 – September 2012 using monthly human landing catches to generate estimates of aEIR as previously described [28]. Malaria transmission at all three sites was perennial, with 2 annual peaks following the rainy seasons. Walukuba is a peri-urban area near Lake Victoria in the south-central part of the country with an estimated aEIR of 3.8 infectious bites per person per year. Kihihi is a rural area in the south-western part of the country, with an estimated aEIR of 26.6. Nagongera is a rural area in the south-eastern part of the country near the Kenyan border, with an estimated aEIR of 125.0. Key malaria control interventions in all three districts include use of LLINs, malaria case management with ACTs, and IPTp with sulfadoxine-pyrimethamine. A single round of IRS using lambda-cyhalothrin was conducted in Kanungu district in 2007 and a mass, community-based campaign to distribute free ITNs was conducted in Tororo district in January 2011.

Bottom Line: Prevalence of anemia (hemoglobin < 11.0 g/dL) was significantly higher in Walukuba (18.9%) and Nagongera (17.4%) than in Kihihi (13.1%), and was strongly associated with decreasing age for those ≤ 5 years at all sites.Parasite prevalence was significantly higher in Nagongera (48.3%) than in Walukuba (12.2%) and Kihihi (12.8%), and significantly increased with age to 11 years, and then significantly decreased at all sites.AMA-1 seroconversion rates strongly correlated with transmission intensity, while serological responses to MSP-119 did not.

View Article: PubMed Central - PubMed

Affiliation: Makerere University School of Public Health, College of Health Sciences, Kampala, Uganda; Infectious Diseases Research Collaboration, Kampala, Uganda.

ABSTRACT

Background: Understanding the current epidemiology of malaria and the relationship between intervention coverage, transmission intensity, and burden of disease is important to guide control activities. We aimed to determine the prevalence of anemia, parasitemia, and serological responses to P. falciparum antigens, and factors associated with these indicators, in three different epidemiological settings in Uganda.

Methods and findings: In 2012, cross-sectional surveys were conducted in 200 randomly selected households from each of three sites: Walukuba, Jinja district (peri-urban); Kihihi, Kanungu district (rural); and Nagongera, Tororo district (rural) with corresponding estimates of annual entomologic inoculation rates (aEIR) of 3.8, 26.6, and 125.0, respectively. Of 2737 participants, laboratory testing was done in 2227 (81.4%), including measurement of hemoglobin, parasitemia using microscopy, and serological responses to P. falciparum apical membrane antigen 1 (AMA-1) and merozoite surface protein 1, 19 kilodalton fragment (MSP-119). Analysis of laboratory results was restricted to 1949 (87.5%) participants aged ≤ 40 years. Prevalence of anemia (hemoglobin < 11.0 g/dL) was significantly higher in Walukuba (18.9%) and Nagongera (17.4%) than in Kihihi (13.1%), and was strongly associated with decreasing age for those ≤ 5 years at all sites. Parasite prevalence was significantly higher in Nagongera (48.3%) than in Walukuba (12.2%) and Kihihi (12.8%), and significantly increased with age to 11 years, and then significantly decreased at all sites. Seropositivity to AMA-1 was 53.3% in Walukuba, 63.0% in Kihihi, and 83.7% in Nagongera and was associated with increasing age at all sites. AMA-1 seroconversion rates strongly correlated with transmission intensity, while serological responses to MSP-119 did not.

Conclusion: Anemia was predominant in young children and parasitemia peaked by 11 years across 3 sites with varied transmission intensity. Serological responses to AMA-1 appeared to best reflect transmission intensity, and may be a more accurate indicator for malaria surveillance than anemia or parasitemia.

No MeSH data available.


Related in: MedlinePlus