Epidemiological risk factors for clinical malaria infection in the highlands of Western Kenya

Essendi, Walters M.; Vardo-Zalik, Anne M.; Lo, Eugenia; Machani, Maxwell G.; Zhou, Guofa; Githeko, Andrew K.; Yan, Guiyun; Afrane, Yaw A.

doi:10.1186/s12936-019-2845-4

Cited by 38 publications

(45 citation statements)

References 22 publications

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“…The same risk factors are also associated with higher vector density. These findings are consistent with other studies [28]. Some studies have reported an increased parasitaemia in children living at low altitudes compared to those who lived at high altitudes [29].…”

Section: Discussionsupporting

confidence: 93%

Risk Factors for Malaria Infection Prevalence and Household Vector Density between Mass Distribution Campaigns of Long-Lasting Insecticidal Nets in Northern Tanzania

Mosha

Lukole²,

Charlwood³

et al. 2020

Preprint

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Background Long lasting insecticide nets (LLIN) are the intervention most widely deployed in Sub-Saharan Africa to prevent malaria. Recent reports indicate selection of pyrethroid insecticide resistance is widespread in mosquito vectors. This paper explores the risk factors associated with malaria infection prevalence and vector density between mass distribution campaigns of LLIN in Northern Tanzania. Methods A cross sectional malaria survey of 3,456 children was undertaken in 2014. Vector density was assessed using indoor light traps and outdoor tent traps. Anophelines were identified to species using PCR and tested for falciparum circumsporozoite protein. Logistic regression was used to identify household and environmental factors associated with malaria infection and vector density. Results LLIN use was 27.7%. Only 16.9% of households had sufficient nets to cover all sleeping places. Malaria infection was independently associated with access to LLIN (OR: 0.57; 95%CI 0.34 – 0.98), age group, altitude and house construction quality. LLIN less than 2 years old were more protective than older LLIN (53% vs 65% prevalence of infection); however, there was no evidence that LLIN in good condition (hole index <65) were more protective than LLIN which were more holed. Independent risk factors for vector density were consistent with malaria outcomes and included altitude, wind, livestock, house quality, open eaves and LLIN access. Indoor collections comprised 4.6% Anopheles funestus and 95.4% An. gambiae of which 4.5% were An. arabiensis and 93.5% were An. gambiae s.s . Conclusion Three years after the mass distribution campaign and despite top-ups, LLIN usage had fallen considerably. While children living in households with access to LLIN were at lower risk of malaria, infection prevalence remained high even among users of LLIN in good condition. While effort should be made to maintain high coverage between campaigns, distribution of just standard pyrethroid LLIN appears insufficient to prevent malaria transmission in this area of intense pyrethroid resistance.

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Section: Discussionsupporting

confidence: 93%

Risk Factors for Malaria Infection Prevalence and Household Vector Density between Mass Distribution Campaigns of Long-Lasting Insecticidal Nets in Northern Tanzania

Mosha

Lukole²,

Charlwood³

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…The same risk factors are also associated with higher vector density. These ndings are consistent with other studies [30]. Some studies have reported an increased parasitaemia in children living at low altitudes compared to those who lived at high altitudes [31].…”

Section: Discussionsupporting

confidence: 93%

Risk factors for malaria infection prevalence and household vector density between mass distribution campaigns of long-lasting insecticidal nets in North-western Tanzania

Mosha

Lukole²,

Charlwood³

et al. 2020

Preprint

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Background Long-lasting insecticidal nets (LLINs) are the most widely deployed vector control intervention in sub-Saharan Africa to prevent malaria. Recent reports indicate selection of pyrethroid insecticide resistance is widespread in mosquito vectors. This paper explores risk factors associated with malaria infection prevalence and vector density between mass distribution campaigns, changes in net coverage, and loss of protection in an area of high pyrethroid resistance in Northwest Tanzania. Methods A cross sectional malaria survey of 3,456 children was undertaken in 2014 in Muleba district, Kagera region west of Lake Victoria. Vector density was assessed using indoor light traps and outdoor tent traps. Anophelines were identified to species using PCR and tested for Plasmodium falciparum circumsporozoite protein. Logistic regression was used to identify household and environmental factors associated with malaria infection and regression binomial negative for vector density. Results LLIN use was 27.7%. Only 16.9% of households had sufficient nets to cover all sleeping places. Malaria infection was independently associated with access to LLINs (OR: 0.57; 95%CI 0.34 – 0.98). LLINs less than 2 years old were slightly more protective than older LLINs (53% vs 65% prevalence of infection); however, there was no evidence that LLINs in good condition (hole index <65) were more protective than LLINs which were more holed. Other risk factors for malaria infection were age, group, altitude and house construction quality. Independent risk factors for vector density were consistent with malaria outcomes and included altitude, wind, livestock, house quality, open eaves and LLIN usage. Indoor collections comprised 4.6% Anopheles funestus and 95.4% Anopheles gambiae of which 4.5% were Anopheles arabiensis and 93.5% were Anopheles gambiae sensu stricto. Conclusion Three years after the mass distribution campaign and despite top-ups, LLIN usage had declined considerably. While children living in households with access to LLINs were at lower risk of malaria, infection prevalence remained high even among users of LLINs in good condition. While effort should be made to maintain high coverage between campaigns, distribution of standard pyrethroid-only LLINs appears insufficient to prevent malaria transmission in this area of intense pyrethroid resistance.

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“…These include younger age, male sex, and lower community level wealth 13 . The factors identified in this study, many of which have also been identified in other countries [51][52][53] , are particularly important for identifying infected individuals in the DRC, as many adult infections are asymptomatic and often go undetected 8 . Thus, targeting malaria interventions towards younger adults, men, and poorer communities could maximize their impact.…”

Section: Discussionmentioning

confidence: 75%

Spatial and epidemiological drivers of P. falciparum malaria among adults in the Democratic Republic of the Congo

Deutsch-Feldman¹,

Brazeau²,

Parr

et al. 2020

Preprint

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Background: Malaria remains a significant public health problem in sub-Saharan Africa. Adults are frequently infected and may serve as a reservoir for further transmission, yet we know relatively little about risk factors for adult infections. In this study, we assessed malaria risk factors amongst adults using samples from the nationally representative, cross-sectional 2013-2014 Demographic and Health Survey (DHS) conducted in the Democratic Republic of Congo (DRC). We further explored differences in risk factors by urbanicity. Methods: Plasmodium falciparum infection was determined by polymerase chain reaction (PCR). Covariates were drawn from the DHS to model individual, community, and environmental level risk factors for infection. Additionally, we used deep sequencing data to estimate the community-level proportions of drug resistant infections and included these estimates as potential risk factors. All identified factors were assessed for differences in associations by urbanicity. Results: A total of 16,126 adults were included. Overall prevalence of malaria was 30.3% (SE = 1.1) by PCR; province-level prevalence ranged from 6.7-58.3%. Only 17% of individuals lived in households with at least one bednet for every two people, as recommended by the World Health Organization. Protective factors included increasing within-household bednet coverage (PR = 0.85, 95% CI = 0.76 - 0.95) and modern housing (PR = 0.58, 95% CI = 0.49 - 0.69). Community level protective factors included: increased average education and wealth (PR = 0.77, 95% CI = 0.65-0.91; PR - 0.84, 95% CI = 0.80 - 0.89). Education, wealth, and modern housing showed protective associations in cities but not in rural areas. Conclusions: The DRC continues to suffer from a high burden of malaria; interventions that target high-risk groups and sustained investment in malaria control are sorely needed. Differences in risk factors by urbanicity may be due to differences in transmission intensity or access to resources.

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Epidemiological risk factors for clinical malaria infection in the highlands of Western Kenya

Cited by 38 publications

References 22 publications

Risk Factors for Malaria Infection Prevalence and Household Vector Density between Mass Distribution Campaigns of Long-Lasting Insecticidal Nets in Northern Tanzania

Risk Factors for Malaria Infection Prevalence and Household Vector Density between Mass Distribution Campaigns of Long-Lasting Insecticidal Nets in Northern Tanzania

Risk factors for malaria infection prevalence and household vector density between mass distribution campaigns of long-lasting insecticidal nets in North-western Tanzania

Spatial and epidemiological drivers of P. falciparum malaria among adults in the Democratic Republic of the Congo

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