Doctoral dissertation

The Associations of Malaria and Linear Growth Faltering in Infants and Young Children in Malawi

Tohtori
The geographic overlap between stunting (small length for age) and malaria suggests there is a relationship between the two conditions, but current evidence is inconclusive. Interventions aimed to prevent stunting include improving the quality of complementary foods through home fortification with products such as lipid-based nutrient supplements (LNS). However, there are concerns that LNS, which contains iron, can increase the risk of malaria in children. Hence the need to establish whether a causal relationship exists between stunting and malaria; and whether LNS provision to prevent stunting can increase the risk of malaria.

The study of Jaden Bendabenda was therefore designed to determine: whether linear growth faltering can predict the risk of malaria; whether malaria causes linear growth faltering and poor child development; and whether LNS provision does not increase the risk of malaria. These aims were addressed using data from children enrolled in the International Lipid-based Nutrient Supplements Project (iLiNS) trials (iLiNS- DOSE and iLiNS-DYAD-M), conducted in rural Malawi between 2009 and 2015.

A total of 2,725 six-month old children were enrolled and followed during weekly morbidity home visits, where a diagnosis of presumed malaria was made. Additional malaria data were collected at clinic visits. Anthropometry data were collected at 6 months’ and 18 months’ clinic visits where length-for-age z scores [LAZ] were obtained. Stunting was defined as LAZ <-2. Developmental outcomes (fine motor scores, gross motor scores, language scores and Profile of Social and Emotional Development [PSED] scores) were assessed at 18 months’ clinic visit.

At 18 months, 2,561 (94%) children had complete morbidity data and reported 28,032 morbidity episodes, 9.7% of which were episodes of presumed malaria. The mean (SD) incidence of all illnesses combined was 16.2 (13.1) episodes per child year, of which 1.1 (1.6) were episodes of presumed malaria. On average, the children made 5.5 visits to the hospital due to illness, of which 1.7 were due to malaria. The prevalence of malaria confirmed by microscopy increased from 4.7% to 9.6% between 6 months and 18 months. There was no association of LAZ at 6 months with subsequent 12-month incidence of presumed malaria (incidence rate ratio [IRR] = 1.03; 95% CI = 0.98 to 1.09; p =0.394) or prevalence of malaria parasitaemia at 18 months (prevalence ratio = 1.11; 95% CI = 0.93 to 1.33; p = 0.259).

Between 6 months and 18 months, the mean (SD) change in LAZ was -0.44 (0.77) and the prevalence of stunting increased from 26.7% to 41.2%. At 18 months, the mean (SD) for fine motor, gross motor, language and PSED scores were 20.9 (2.2), 17.3 (2.6), 26.2 (5.0) and 16.2 (5.4) respectively. There was no statistically significant association of presumed malaria incidence with change in LAZ (B = -0.02, 95% CI = -0.04 to 0.01, p = 0.069). Presumed malaria incidence was significantly associated with increased proportion of children with stunting at 18 months (risk ratio = 1.04, 95% CI = 1.01 to 1.07, p = 0.023). The association of presumed malaria incidence with child development at 18 months was significant for PSED scores (B = -0.21; 95% CI = 0.39 to -0.03; p = 0.041), but not for the other domains of child development.

Regarding the safety of LNS, there were no significant differences in the incidence of presumed malaria, clinical malaria nor confirmed malaria across the different doses of LNS. Compared to the control group, the 95% CIs of the IRRs for presumed malaria, clinical malaria, and confirmed malaria were entirely below 1.20 (suggestive of non-inferiority) in all the intervention groups, except for the 40 g/d LNS where the incidence of confirmed malaria was 21% higher in this group than the control.

In conclusion, in a rural Malawian population, where both stunting and malaria are common, but with active surveillance and early treatment of infections, linear growth faltering at 6 months does not predict malaria incidence from 6 months to 18 months. In this population, malaria is not associated with change in LAZ but may increase the risk of stunting and reduce socio-emotional development.

Finally, long term provision of iron-containing LNS at certain doses does not increase the risk of malaria in this population where iron deficiency and mosquito bed net utilization is high. These findings could be useful when designing growth promotion and malaria control interventions for infants and young children in malaria-endemic areas.

 

The doctoral dissertation of Jaden Bendabenda in the field of international medicine titled The Associations of Malaria and Linear Growth Faltering in Infants and Young Children in Malawi will be publicly examined in the Faculty of Medicine and Health Technology at Tampere University on Friday 24 Jan 2020 at 12 o'clock in Arvo building Jarmo Visakorpi auditorium, Arvo Ylpön katu 34. The Opponent will be Docent Päivi Tapanainen, University of Oulu. The Custos will be Professor Per Ashorn.

The dissertation is available online at http://urn.fi/URN:ISBN:978-952-03-1416-3