Toxocara Seropositivity, Atopy and Wheezing in Children Living in Poor Neighbourhoods in Urban Latin American

Abstract

Background Toxocara canis and T. cati are parasites of dogs and cats, respectively, that infect humans and cause human toxocariasis. Infection may cause asthma-like symptoms but is often asymptomatic and is associated with a marked eosinophilia. Previous epidemiological studies indicate that T. canis infection may be associated with the development of atopy and asthma.ObjectivesTo investigate possible associations between Toxocara spp. seropositivity and atopy and childhood wheezing in a population of children living in non-affluent areas of a large Latin American city.MethodsThe study was conducted in the city of Salvador, Brazil. Data on wheezing symptoms were collected by questionnaire, and atopy was measured by the presence of aeroallergen-specific IgE (sIgE). Skin prick test (SPT), total IgE and peripheral eosinophilia were measured. Toxocara seropositivity was determined by the presence of anti-Toxocara IgG antibodies, and intestinal helminth infections were determined by stool microscopy.FindingsChildren aged 4 to 11 years were studied, of whom 47% were seropositive for anti-Toxocara IgG; eosinophilia >4% occurred in 74.2% and >10% in 25.4%; 59.6% had elevated levels of total IgE; 36.8% had sIgE≥0.70 kU/L and 30.4% had SPT for at least one aeroallergen; 22.4% had current wheezing symptoms. Anti-Toxocara IgG was positively associated with elevated eosinophils counts, total IgE and the presence of specific IgE to aeroallergens but was inversely associated with skin prick test reactivity.ConclusionThe prevalence of Toxocara seropositivity was high in the studied population of children living in conditions of poverty in urban Brazil. Toxocara infection, although associated with total IgE, sIgE and eosinophilia, may prevent the development of skin hypersensitivity to aeroallergens, possibly through increased polyclonal IgE and the induction of a modified Th2 immune reaction.

Contamination by parasites of zoonotic importance in fecal samples from Florianópolis Beaches, Santa Catarina State, Brazil

“…In different regions of Brazil, numerous cases of visceral and cutaneous larva migrans have been described for humans (MUSSO et al, 2007;SCHUSTER et al, 2013), and serological data have confirmed elevated level of exposure of humans to Toxocara spp. (FRAGOSO et al, 2011;SOUZA et al, 2011;MATTIA et al, 2012;MENDONÇA et al, 2012;SCHOENARDIE et al, 2013).…”

A Systematic Review of Toxocariasis: A Neglected But High-Prevalence Disease in Brazil

“…10,27,[30][31][32]36,40 In all of these studies, a higher proportion of patients with asthma was found among those infected with Toxocara, which lends this infection greater relevance in terms of public health.…”

“…The study investigated the possible association between seropositivity for Toxocara, atopy, and childhood wheezing in a population of children in poor areas of the city. 40 Also in the city of Salvador, another study, which examined 338 middle-and lower-class individuals, found a higher prevalence of toxocariasis among those of the lower class and those with greater contact with dogs and cats. The study also showed that being in the lower class was associated with a higher risk of infection with T. canis.…”

“…10,[24][25][26][27][28][29][31][32][33][34][36][37][38][39][40][41][42][43][44] One study did not describe the diagnostic methodology applied. 35 As T. canis and T. cati cannot be distinguished serologically, we identified the study population as having toxocariasis.…”

Epidemiology and Control of Child Toxocariasis in the Western Brazilian Amazon – A Population-Based Study

“…Other studies have indicated the existence of an association between toxocariasis and other helminth infections, such as T. trichiura, Schistosoma mansoni, and A. lumbricoides 61,62 ; this association can be explained because the mechanism of transmission of Toxocara spp. is similar to other helminthes, and therefore, the risk of infection is similar in areas where these parasites co-exist.…”