Total and specific IgE (house dust mite and intestinal helminths) in asthmatics and controls from Gondar, Ethiopia

108

Background: Allergic diseases seem less prevalent in communities in less developed parts of the world, where parasite infections are highly prevalent. Altogether not much is known about the association between chronic infections with tissue and blood-dwelling parasites and atopy. Methods: In an area in Gabon endemic for blood and tissue parasites, 520 schoolchildren were parasitologically examined and skin prick-tested for a set of common environmental aeroallergens. Levels of allergen-specific IgE and polyclonal IgE were measured. Results: In schoolchildren schistosome and filarial infections increased with age, whereas malaria was more prevalent in younger children. In contrast to allergen sensitization that increased with age, skin test reactivity tended to decline. The number of children with mite-specific IgE antibodies (47%) by far exceeded the number responding to skin prick testing (11%). Mite sensitization was found to be the highest in children infected with schistosomes and/or filariae whereas skin test reactivity was lowest. The multiple logistic regression showed that the risk of a positive skin test was 8-fold higher with increasing levels of mite-specific IgE but was reduced by 72% when infected with blood stage helminths. Conclusions: Chronic blood and tissue parasite infections that are often capable of modulating immune responses in the host are negatively associated with skin test reactivity in a sensitized population.

Section: Discussionsupporting

confidence: 89%

The Prevalence of Parasite Infestation and House Dust Mite Sensitization in Gabonese Schoolchildren

Biggelaar

Lopuhaä

Ree

et al. 2001

108

“…D. pteronyssinus- sensitised patients were frequently co-sensitised with other allergen sources. The prevalence of house dust mite sensitisation reported in this selected population corroborates data from earlier Zimbabwean reports [7, 15]and is in agreement with reports from Ethiopia [16], Kenya [17], Tanzania [5], Nigeria [4, 18], Gabon [19], South Africa [20]and Ghana [21]. While rates of IgE antibody reactivity to the major Der p 2 allergen, for example, are similar in European and African sera, reactivity to Der p 5, Der p 7 and Der p 10 has been shown to be much higher in the latter population [14].…”

Section: Allergen Sourcessupporting

confidence: 92%

Inhalant Allergies in Zimbabwe: A Common Problem

Sibanda¹

2003

Allergic rhinitis, allergic conjunctivitis, allergic asthma and atopic dermatitis affect a quarter of the population of the industrialised countries and are the most common symptoms of type I hypersensitivity reactions. Their prevalence has been documented in many communities, yet data from Africa are limited. In the 5-year period from September 1997 to September 2002, approximately 14,000 patients of all ages were referred to the only specialist allergy clinic in Harare, Zimbabwe, for allergy investigation, diagnosis and therapeutic management. In approximately one tenth of these patients, food allergies were diagnosed; less frequent presentations included allergic pharyngitis, bee- or wasp-induced reactions and latex allergy. An allergologic basis for the clinical conditions was established following a careful clinical and physical examination, evaluation of family history and the detection of in vivo (skin prick test) or in vitro (radio-allergo-sorbent test; RAST) allergen-specific IgE antibodies to known sources of inhalant allergens, using commercial allergen extracts and a RAST assay kit. Asthma diagnosis was supported by the clinical and laboratory findings of salbutamol-reversible airways obstruction. Case files of the first 1,046 patients are reviewed in order to define the clinical presentation of allergic patients in this region. It is highlighted that allergy in general and inhalant allergy in particular are very common, if not widely acknowledged, clinical problems in this Central African region.

“…Although the results do not reach statistical significance (p = 0.10), most probably due to the small number of microfilaria-positive subjects, the data suggest that the presence of microfilariae in blood has a protective effect on mite SPT reactivity. This is in agreement with the findings that schistosomes and intestinal helminths reduce the risk of atopy [8, 30], asthma [58] or wheeze [9]. However, when antifilarial IgG4 was used as an indicator of active infection, no effect of infection on SPT positivity was observed.…”

Section: Discussionsupporting

confidence: 91%

Clustering of Allergic Outcomes within Families and Households in Areas Endemic for Helminth Infections

Wahyuni

Sartono²,

Supali

et al. 2005

Background: Allergy and helminth infections share key immunological features in terms of Th2 responses. Although in industrialized countries clustering of allergic disorders within families has been frequently reported, such information is lacking from areas where helminth infections are endemic. Methods: A total of 466 subjects from 29 families and 112 households participated in this study. Filarial infection, skin test reactivity and IgE to mite as well as total IgE were measured in all samples. Clustering of the allergy-related outcomes due to genetic and household factors was tested. Results: Genetic factors contributed significantly to the clustering of total IgE and allergen-specific IgE, whereas only household factors contributed to the clustering of SPT positivity. Conclusion: Similar to several studies conducted in western populations, total IgE and allergen-specific IgE are influenced by genetic factors in a population resident in a helminth endemic area. However, clustering of SPT positivity due to genetic factors was not significant in the current study raising the question of whether the presence of helminth infections may override genes that are associated with the expression of tissue reactivity to allergens in the west.