High Iron Stores in the Low Malaria Season Increase Malaria Risk in the High Transmission Season in a Prospective Cohort of Rural Zambian Children

IntroductionMalawi’s malaria burden is primarily assessed via cross-sectional national household surveys. However, malaria is spatially and temporally heterogenous and no analyses have been performed at a subdistrict level throughout the course of a year. The WHO recommends mass distribution of long-lasting insecticide-treated bed nets (LLINs) every 3 years, but a national longitudinal evaluation has never been conducted in Malawi to determine LLIN effectiveness lifespans.MethodsUsing District Health Information Software 2 (DHIS2) health facility data, available from January 2018 to June 2020, we assessed malaria risk before and after a mass distribution campaign, stratifying by age group and comparing risk differences (RDs) by LLIN type or annual application of indoor residual spraying (IRS).Results711 health facilities contributed 20 962 facility reports over 30 months. After national distribution of 10.7 million LLINs and IRS in limited settings, malaria risk decreased from 25.6 to 16.7 cases per 100 people from 2018 to 2019 high transmission seasons, and rebounded to 23.2 in 2020, resulting in significant RDs of −8.9 in 2019 and −2.4 in 2020 as compared with 2018. Piperonyl butoxide (PBO)-treated LLINs were more effective than pyrethroid-treated LLINs, with adjusted RDs of −2.3 (95% CI −2.7 to −1.9) and −1.5 (95% CI −2.0 to −1.0) comparing 2019 and 2020 high transmission seasons to 2018. Use of IRS sustained protection with adjusted RDs of −1.4 (95% CI −2.0 to −0.9) and −2.8% (95% CI −3.5 to −2.2) relative to pyrethroid-treated LLINs. Overall, 12 of 28 districts (42.9%) experienced increases in malaria risk in from 2018 to 2020.ConclusionLLINs in Malawi have a limited effectiveness lifespan and IRS and PBO-treated LLINs perform better than pyrethroid-treated LLINs, perhaps due to net repurposing and insecticide-resistance. DHIS2 provides a compelling framework in which to examine localised malaria trends and evaluate ongoing interventions.

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Asymptomatic malaria and anaemia among pregnant women during high and low malaria transmission seasons in Burkina Faso: household-based cross-sectional surveys in Burkina Faso, 2013 and 2017

Malaria Journal ◽

10.1186/s12936-021-03703-4 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Toussaint Rouamba ◽

Sékou Samadoulougou ◽

Mady Ouédraogo ◽

Hervé Hien ◽

Halidou Tinto ◽

...

Keyword(s):

Burkina Faso ◽

Pregnant Women ◽

Malaria Transmission ◽

Asymptomatic Malaria ◽

Cross Sectional ◽

Transmission Season ◽

Low Transmission ◽

High Transmission ◽

Asymptomatic Carriage ◽

Low Malaria Transmission

Abstract Background Malaria in endemic countries is often asymptomatic during pregnancy, but it has substantial consequences for both the mother and her unborn baby. During pregnancy, anaemia is an important consequence of malaria infection. In Burkina Faso, the intensity of malaria varies according to the season, albeit the prevalence of malaria and anaemia as well as their risk factors, during high and low malaria transmission seasons is underexplored at the household level. Methods Data of 1751 pregnant women from October 2013 to March 2014 and 1931 pregnant women from April 2017 to June 2017 were drawn from two cross-sectional household surveys conducted in 24 health districts of Burkina Faso. Pregnant women were tested for malaria in their household after consenting. Asymptomatic carriage was defined as a positive result from malaria rapid diagnostic tests in the absence of clinical symptoms of malaria. Anaemia was defined as haemoglobin level less than 11 g/dL in the first and third trimester and less than 10.5 g/dL in the second trimester of pregnancy. Results Prevalence of asymptomatic malaria in pregnancy was estimated at 23.9% (95% CI 20.2–28.0) during the high transmission season (October–November) in 2013. During the low transmission season, it was 12.7% (95% CI 10.9–14.7) between December and March in 2013–2014 and halved (6.4%; 95% CI 5.3–7.6) between April and June 2017. Anaemia prevalence was estimated at 59.4% (95% CI 54.8–63.8) during the high transmission season in 2013. During the low transmission season, it was 50.6% (95% CI 47.7–53.4) between December and March 2013–2014 and 65.0% (95% CI 62.8–67.2) between April and June, 2017. Conclusion This study revealed that the prevalence of malaria asymptomatic carriage and anaemia among pregnant women at the community level remain high throughout the year. Thus, more efforts are needed to increase prevention measures such as IPTp–SP coverage in order to reduce anaemia and contribute to preventing low birth weight and poor pregnancy outcomes.

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Iron Status of Burkinabé Adolescent Girls Predicts Malaria Risk in the Following Rainy Season

Nutrients ◽

10.3390/nu12051446 ◽

2020 ◽

Vol 12 (5) ◽

pp. 1446 ◽

Cited By ~ 1

Author(s):

Loretta Brabin ◽

Stephen A. Roberts ◽

Halidou Tinto ◽

Sabine Gies ◽

Salou Diallo ◽

...

Keyword(s):

Adolescent Girls ◽

Rainy Season ◽

Iron Supplementation ◽

Iron Status ◽

Malaria Risk ◽

Infection Prevalence ◽

Asymptomatic Malaria ◽

Body Iron ◽

Iron Stores ◽

Safety Outcome

High levels of storage iron may increase malaria susceptibility. This risk has not been investigated in semi-immune adolescents. We investigated whether baseline iron status of non-pregnant adolescent girls living in a high malaria transmission area in Burkina Faso affected malaria risk during the following rainy season. For this prospective study, we analysed data from an interim safety survey, conducted six months into a randomised iron supplementation trial. We used logistic regression to model the risk of P. falciparum infection prevalence by microscopy, the pre-specified interim safety outcome, in relation to iron status, nutritional indicators and menarche assessed at recruitment. The interim survey was attended by 1223 (82%) of 1486 eligible participants, 1084 (89%) of whom were <20 years at baseline and 242 (22%) were pre-menarcheal. At baseline, prevalence of low body iron stores was 10%. At follow-up, 38% of adolescents had predominantly asymptomatic malaria parasitaemias, with no difference by menarcheal status. Higher body iron stores at baseline predicted an increased malaria risk in the following rainy season (OR 1.18 (95% CI 1.05, 1.34, p = 0.007) after adjusting for bed net use, age, menarche, and body mass index. We conclude that routine iron supplementation should not be recommended without prior effective malaria control.

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Measurement of Antibody Levels against Region II of the Erythrocyte-Binding Antigen 175 of Plasmodium falciparum in an Area of Malaria Holoendemicity in Western Kenya

Infection and Immunity ◽

10.1128/iai.72.2.735-741.2004 ◽

2004 ◽

Vol 72 (2) ◽

pp. 735-741 ◽

Cited By ~ 25

Author(s):

Eunita A. Ohas ◽

John H. Adams ◽

John N. Waitumbi ◽

Alloys S. S. Orago ◽

Arnoldo Barbosa ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Sialic Acid ◽

Inhibitory Activity ◽

Western Kenya ◽

Transmission Season ◽

High Transmission ◽

Exposed Population ◽

Erythrocyte Binding ◽

Antibody Levels ◽

Region Ii

ABSTRACT Region II of the 175-kDa erythrocyte-binding antigen (EBA-175RII) of Plasmodium falciparum is functionally important in sialic acid-dependent erythrocyte invasion and is considered a prime target for an invasion-blocking vaccine. The objectives of this study were to (i) determine the prevalence of anti-EBA-175RII antibodies in a naturally exposed population, (ii) determine whether naturally acquired antibodies have a functional role by inhibiting binding of EBA-175RII to erythrocytes, and (iii) determine whether antibodies against EBA-175RII correlate with immunity to clinical malaria. We treated 301 lifelong residents of an area of malaria holoendemicity in western Kenya for malaria, monitored them during a high-transmission season, and identified 33 individuals who were asymptomatic despite parasitemia (clinically immune). We also identified 50 clinically susceptible individuals to serve as controls. These 83 individuals were treated and monitored again during the subsequent low-transmission season. Anti-EBA-175RII antibodies were present in 98.7% of the individuals studied. The antibody levels were relatively stable between the beginning and end of the high-transmission season and correlated with the plasma EBA-175RII erythrocyte-binding-inhibitory activity. There was no difference in anti-EBA-175RII levels or plasma EBA-175RII erythrocyte-binding-inhibitory activity between clinically immune and clinically susceptible groups. However, these parameters were higher in nonparasitemic than in parasitemic individuals at enrollment. These results suggest that although antibodies against EBA-175RII may be effective in suppressing some of the wild parasite strains, EBA-175RII is unlikely to be effective as a monovalent vaccine against malaria, perhaps due to allelic heterogeneity and/or presence of sialic acid-independent strains.

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