Life‐course of atopy and allergy‐related disease events in tropical sub‐Saharan Africa: A birth cohort study

Abstract

BackgroundIn high‐income countries, allergy‐related diseases (ARDs) follow a typical sequence, the ‘Atopic March’. Little is known about the life‐course of ARDs in the markedly different, low‐income, tropical environment. We describe ARDs in a tropical, African birth cohort.MethodsUgandan children were followed from birth to 9 years. ISAAC questionnaires were completed at intervals; doctor‐diagnosed ARDs were recorded throughout follow‐up. Skin prick tests (SPTs) were performed at 3 and 9 years. Atopy was defined as ≥1 positive SPT.ResultsOf the 2345 live‐born children, 1214 (52%) were seen at 9 years. Wheeze and eczema were common in infancy, but by 9 years, only 4% reported recent wheeze, 5% eczema and 5% rhinitis. Between 3 and 9 years, atopy prevalence increased from 19% to 25%. Atopy at 3 or 9 years was associated with reported ARD events at 9 years, for example OR = 5.2 (95% CI 2.9–10.7) for atopy and recent wheeze at 9 years. Reported or doctor‐diagnosed ARD events in early childhood were associated with the same events in later childhood, for example OR = 4.4 (2.3–8.4) for the association between reported wheeze before 3 years with reported recent wheeze at 9 years, but progression from early eczema to later rhinitis or asthma was not observed.ConclusionAllergen sensitization started early in childhood and increased with age. Eczema and wheeze were common in infancy and declined with age. Atopy was strongly associated with ARD among the few affected children. The typical Atopic March did not occur. Environmental exposures during childhood may dissociate atopy and ARD.

The environment and its effect on allergic sensitization and atopic dermatitis, and colostrum and the immune system of the preterm infant

“…In the first of my highlighted articles, Zakzuk and colleagues have investigated the pattern of sensitization to Blomia tropicalis, a common tropical mite, as well as to Ascaris in a population of children living in a low‐income neighborhood in Cartagena, Colombia . Such an environment is definitely of interest, as has been shown earlier in PAI that the presence of parasites might influence allergies . As expected and shown earlier in birth cohorts from high‐income countries in the Western Hemisphere, sensitization increases gradually during the first years of life .…”

Effects of treating helminths during pregnancy and early childhood on risk of allergy‐related outcomes: Follow‐up of a randomized controlled trial

“…19 Evaluation of the time course of ARD in this cohort showed a high prevalence and incidence of eczema in infancy but a marked decline in ARD with age, and no significant emergence of asthma at school age. 20 By contrast, the prevalence of atopy increased. This further emphasizes the dissociation between atopy and ARD.…”

“…These results are in keeping with the persistent effect of maternal albendazole treatment observed at age five 17 and with the observation that eczema in early life was associated with eczema at age 9 years in this cohort (Lule et al, under review, Ped Allergy Immunol). In addition, there was a suggestion of (20) 42 (18) an adverse effect of maternal albendazole treatment on prevalence of rhinitis in 9-year-olds. Thus, for ARD other than wheeze, our findings are consistent with a persistent, weak, adverse effect of the early-life interventions, but are inconclusive.…”

Epithelial barrier dysfunctions in atopic dermatitis: a skin-gut-lung model linking microbiome alteration and immune dysregulation

“…The complexity of atopic diseases commonly invokes the argument as to whether immunogen (medications, stress, toxins, bacteria, food particles) entry through leaky gut or airways causes systemic atopic responses that include AD, or whether immunogen entry through leaky skin causes systemic atopic responses that include asthma and food allergies. Recent work suggests that only a small proportion of children (4–25%) actually follow a trajectory profile similar to that of the atopic march . In addition approximately 20% of patients do not have any evidence of IgE sensitization (based on skin prick tests), suggesting a degree of heterogeneity within the population.…”

“…Recent work suggests that only a small proportion of children (4-25%) actually follow a trajectory profile similar to that of the atopic march. 66 In addition approximately 20% of patients do not have any evidence of IgE sensitization (based on skin prick tests), suggesting a degree of heterogeneity within the population. As not all individuals show sequential disease progression from AD ?…”