Mosquito Net Use in Early Childhood and Survival to Adulthood in Tanzania

Critically High Burden of Acute Malnutrition and Its Associated Factors Among Children Under 5 Years in the Rural Settings of Southern Ethiopia

BACKGROUND

Globally, acute malnutrition threatens the lives of several million children under 5 years of age. Malnutrition affects the social, economic, and medical aspects of all countries. In Ethiopia, acute malnutrition is not decreasing at the intended rate for unclear reasons.

OBJECTIVE

This study aimed to assess the burden of acute malnutrition and its associated factors among children under 5 years of age in a rural setting of southern Ethiopia.

METHODS

A community-based cross-sectional study was conducted from January to March 2022. A multistage sampling technique was used to select 421 children. Mothers/caretakers were interviewed using interviewer-administered questionnaire, while their children's height/length and weight were measured. Logistic regression analyses were used and presented as the crude odds ratio (COR) and adjusted odds ratio (AOR) with their 95% confidence intervals (CI).

RESULTS

The burden of acute malnutrition among children under 5 years of age in the study area was 22.6% (95% CI = 18.5-26.8). Fathers with primary education (AOR = 4.48; 95% CI = 1.93-10.39), households with improper solid waste disposal (AOR = 2.54; 95% CI = 1.11-5.82), not usually sleeping under insecticide-treated bed net (ITN) (AOR = 1.79; 95% CI = 1.01-3.19), unacceptable children dietary diversity score (DDS) (AOR = 2.56; 95% CI = 1.28-5.14), and unacceptable household DDS (AOR = 2.26; 95% CI = 1.02-5.00) were factors associated with acute malnutrition.

CONCLUSIONS

The prevalence of acute malnutrition among children was critically high. Upgrading paternal educational status, encouraging safe solid waste disposal, ensuring consistent use of ITN, and improving both child and household DDS should be stressed.

Effect of malaria prevention education on bed net utilization, incidence of malaria and treatment seeking among school-aged children in Southern Ethiopia; cluster randomized controlled trial

BACKGROUND

School-aged children (SAC) have an increased risk to contract malaria and play a major role in its transmission dynamics. However, their malaria prevention experience is poor. Thus, the effect of malaria prevention education (MPE) on bed net utilization, treatment seeking from a health facility and cumulative incidence of malaria was evaluated in Southern Ethiopia.

METHODS

A two arm cluster randomized controlled trial was conducted by recruiting 2038 SAC from 32 schools. Structured questionnaire was used to collect data on socio-demographic, economic, bed net ownership, bed net utilization, whether the participated child suffered from malaria and has got treatment from a health facility. Generalized mixed effect logistic regression using school as random variable was used to assess the effect of the intervention on the outcome variables.

RESULTS

The ownership of bed net in households of the control and intervention schools was similar respectively with 84.6 and 88.6% (Crude Odds Ratio (COR): 1.5; 95%CI: 0.5-4.8). The percentage of SAC slept under the bed net the night before the survey was also similar (55.1% versus 54.0%); COR:1.04; 95%CI: 0.5-2.4). Bed net utilization was affected by household size to the bed net ratio ≤ 2 (Adjusted Odds Ratio (AOR) = 1.6; 95%CI:1.3-2.1), bed net utilization at baseline of the study (AOR = 2.3; 95%CI:1.5-3.6), and history of malaria attack in the last twelve months (AOR = 1.3; 95%CI:1.01-1.8). Reported cumulative incidence of malaria and treatment seeking from a health facility by SAC was similar between intervention and control arms: -2.1% (COR = 0.8; 95%CI: 0.5-1.5) and 9.6% (COR = 1.4; 95%CI: 0.4-4.3) respectively. The reported incidence of malaria was affected by altitude (AOR = 0.5; 95%CI: 0.3-0.8), low and medium wealth index (AOR = 0.7; 95%CI: 0.5-0.96 and AOR = 0.7; 95%CI: 0.5-0.98), adequate bed net number for household members (AOR = 0.7; 95%CI:0.5-0.9) and bed net utilization (AOR = 1.3; 95%CI:1.1-1.8).

CONCLUSIONS

MPE had no significant effect on the use of malaria prevention measures considered, treatment seeking from a health facility and reported cumulative incidence of malaria though bed net use was associated with malaria incidence. Before organizing any health education program, sustainable implementation efforts have to be warranted especially in SAC, a neglected but relevant vulnerable and reservoirs.

TRIAL REGISTRATION

Pan African Clinical Trials Registry PACTR202001837195738, registered 21/01/2020.

Associations between the use of insecticide-treated nets in early childhood and educational outcomes, marriage and child-bearing in early adulthood: evidence from a 22-year prospective cohort study in Tanzania

BACKGROUND

The effectiveness of insecticide-treated nets (ITNs) in preventing malaria in young children is well established. However, the long-term effects of early childhood ITN use on educational outcomes, fertility, and marriage in early adulthood are not well understood.

METHODS

This study uses 22 years of longitudinal data from rural Tanzania to investigate the associations between early life ITN use and educational attainment, fertility and marriage in early adulthood. Unadjusted and adjusted logistic regression models were used to estimate the associations between early life ITN use and early adult outcomes (education, childbearing, and marriage), controlling for potential confounders, such as parental education, household asset quintiles, and year of birth. Analyses were conducted separately for men and women.

RESULTS

A total of 6706 participants born between 1998 and 2000 were enrolled in the study between 1998 and 2003. By 2019 a total of 604 had died and a further 723 could not be found, leaving 5379 participants who were interviewed, among whom complete data were available for 5216. Among women, sleeping under a treated net at least half of the time during early childhood ["high ITN use"] was associated with a 13% increase in the odds of completing primary school (adjusted odds ratio (aOR) 1.13 [0.85, 1.50]) and with a 40% increase in the odds of completing secondary school (aOR 1.40 [1.11, 1.76]) compared with women sleeping less frequently under ITNs in early life (< age 5 years). Among men, high ITN use was associated with a 50% increase in the odds of completing primary school (aOR 1.50 [1.18, 1.92]) and a 56% increase in the odds of completing secondary school (aOR 1.56 [1.16, 2.08]) compared to men with low ITN use in early life. Weaker associations were found between ITN use in early life and both adolescent childbearing (aOR 0.91 [0.75, 1.10]) and early marriage (aOR 0.86 [0.69, 1.05]).

CONCLUSION

This study found that early life use of ITNs was strongly associated with increased school completion in both men and women. More marginal associations were found between early-life ITN use and both marriage and child-bearing in early adulthood. ITN use during early childhood may have long-term positive effects on educational attainment in Tanzania. However, further research is needed to understand the mechanisms behind these associations and to explore the broader impacts of ITN use on other aspects of early adult life.

Characterizing pyrethroid resistance and mechanisms in Anopheles gambiae (s.s.) and Anopheles arabiensis from 11 districts in Uganda

Insecticide resistance threatens recent progress on malaria control in Africa. To characterize pyrethroid resistance in Uganda, Anopheles gambiae (s.s.) and Anopheles arabiensis were analyzed from 11 sites with varied vector control strategies. Mosquito larvae were collected between May 2018 and December 2020. Sites were categorized as receiving no indoor-residual spraying ('no IRS', n ​= ​3); where IRS was delivered from 2009 to 2014 and in 2017 and then discontinued ('IRS stopped', n ​= ​4); and where IRS had been sustained since 2014 ('IRS active', n ​= ​4). IRS included bendiocarb, pirimiphos methyl and clothianidin. All sites received long-lasting insecticidal nets (LLINs) in 2017. Adult mosquitoes were exposed to pyrethroids; with or without piperonyl butoxide (PBO). Anopheles gambiae (s.s.) and An. arabiensis were identified using PCR. Anopheles gambiae (s.s.) were genotyped for Vgsc-995S/F, Cyp6aa1, Cyp6p4-I236M, ZZB-TE, Cyp4j5-L43F and Coeae1d, while An. arabiensis were examined for Vgsc-1014S/F. Overall, 2753 An. gambiae (s.l.), including 1105 An. gambiae (s.s.) and 1648 An. arabiensis were evaluated. Species composition varied by site; only nine An. gambiae (s.s.) were collected from 'IRS active' sites, precluding species-specific comparisons. Overall, mortality following exposure to permethrin and deltamethrin was 18.8% (148/788) in An. gambiae (s.s.) and 74.6% (912/1222) in An. arabiensis. Mortality was significantly lower in An. gambiae (s.s.) than in An. arabiensis in 'no IRS' sites (permethrin: 16.1 vs 67.7%, P ​< ​0.001; deltamethrin: 24.6 vs 83.7%, P ​< ​0.001) and in 'IRS stopped' sites (permethrin: 11.3 vs 63.6%, P ​< ​0.001; deltamethrin: 25.6 vs 88.9%, P ​< ​0.001). When PBO was added, mortality increased for An. gambiae (s.s.) and An. arabiensis. Most An. gambiae (s.s.) had the Vgsc-995S/F mutation (95% frequency) and the Cyp6p4-I236M resistance allele (87%), while the frequency of Cyp4j5 and Coeae1d were lower (52% and 55%, respectively). Resistance to pyrethroids was widespread and higher in An. gambiae (s.s.). Where IRS was active, An. arabiensis dominated. Addition of PBO to pyrethroids increased mortality, supporting deployment of PBO LLINs. Further surveillance of insecticide resistance and assessment of associations between genotypic markers and phenotypic outcomes are needed to better understand mechanisms of pyrethroid resistance and to guide vector control.

Microsporidia: a promising vector control tool for residual malaria transmission

Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) have resulted in a major decrease in malaria transmission. However, it has become apparent that malaria can be effectively transmitted despite high coverage of LLINs/IRS. Residual transmission can occur due to Plasmodium-carrying Anopheles mosquitoes that are insecticide resistant and have feeding and resting behavior that reduces their chance of encountering the currently deployed indoor malaria control tools. Residual malaria transmission is likely to be the most significant hurdle to achieving the goal of malaria eradication and research and development towards new tools and strategies that can control residual malaria transmission is therefore critical. One of the most promising strategies involves biological agents that are part of the mosquito microbiome and influence the ability of Anopheles to transmit Plasmodium. These differ from biological agents previously used for vector control in that their primary effect is on vectoral capacity rather than the longevity and fitness of Anopheles (which may or may not be affected). An example of this type of biological agent is Microsporidia MB, which was identified in field collected Anopheles arabiensis and caused complete inhibition of Plasmodium falciparum transmission without effecting the longevity and fitness of the host. Microsporidia MB belongs to a unique group of rapidly adapting and evolving intracellular parasites and symbionts called microsporidia. In this review we discuss the general biology of microsporidians and the inherent characteristics that make some of them particularly suitable for malaria control. We then discuss the research priorities for developing a transmission blocking strategy for the currently leading microsporidian candidate Microsporidia MB for malaria control.

A Brief History of Malaria

For millions of years, invertebrates and malaria parasites have coexisted and to date, malaria remains the most important human parasitic disease. This co-evolution had profound impacts on the movements of early hominids and on the genome of modern humans. Over the past two centuries, progress has been made with the discovery of the parasite, its transmission, and medicines, paving the way to the control of the disease and its elimination in some countries. However, the Plasmodium parasite is a formidable foe capable of developing resistance to drugs, and the mosquito vector has adapted to insecticides, foiling all attempts to eradicate the disease. Over recent years the economic and social costs of malaria have been recognized and more funds have been mobilized than ever before, however further efforts are needed. National programs, international institutions and researchers will need to do better if the preventable deaths of hundreds of thousands of mostly African children are to be averted.

Resurgent and delayed malaria

The populations of moderate or highly malaria endemic areas gradually acquire some immunity to malaria as a result of repeated exposure to the infection. When this exposure is reduced as a result of effective malaria control measures, subjects who benefitted from the intervention may consequently be at increased risk of malaria if the intervention is withdrawn, especially if this is done abruptly, and an effective malaria vector remains. There have been many examples of this occurring in the past, a phenomenon often termed ‘rebound malaria’, with the incidence of malaria rebounding to the level present before the intervention was introduced. Because the main clinical burden of malaria in areas with a high level of malaria transmission is in young children, malaria control efforts have, in recent decades, focussed on this group, with substantial success being obtained with interventions such as insecticide treated mosquito nets, chemoprevention and, most recently, malaria vaccines. These are interventions whose administration may not be sustained. This has led to concerns that in these circumstances, the overall burden of malaria in children may not be reduced but just delayed, with the main period of risk being in the period shortly after the intervention is no longer given. Although dependent on the same underlying process as classical ‘resurgent’ malaria, it may be helpful to differentiate the two conditions, describing the later as ‘delayed malaria’. In this paper, some of the evidence that delayed malaria occurs is discussed and potential measures for reducing its impact are suggested.