Toxoplasmosis in humans and animals in Brazil: high prevalence, high burden of disease, and epidemiology

Abstract

<jats:title>SUMMARY</jats:title><jats:p>Infections by the protozoan parasite<jats:italic>Toxoplasma gondii</jats:italic>are widely prevalent in humans and animals in Brazil. The burden of clinical toxoplasmosis in humans is considered to be very high. The high prevalence and encouragement of the Brazilian Government provides a unique opportunity for international groups to study the epidemiology and control of toxoplasmosis in Brazil. Many early papers on toxoplasmosis in Brazil were published in Portuguese and often not available to scientists in English-speaking countries. In the present paper we review prevalence, clinical spectrum, molecular epidemiology, and control of<jats:italic>T. gondii</jats:italic>in humans and animals in Brazil. This knowledge should be useful to biologists, public health workers, veterinarians, and physicians. Brazil has a very high rate of<jats:italic>T. gondii</jats:italic>infection in humans. Up to 50% of elementary school children and 50–80% of women of child-bearing age have antibodies to<jats:italic>T. gondii</jats:italic>. The risks for uninfected women to acquire toxoplasmosis during pregnancy and fetal transmission are high because the environment is highly contaminated with oocysts. The burden of toxoplasmosis in congenitally infected children is also very high. From limited data on screening of infants for<jats:italic>T. gondii</jats:italic>IgM at birth, 5–23 children are born infected per 10 000 live births in Brazil. Based on an estimate of 1 infected child per 1000 births, 2649 children with congenital toxoplasmosis are likely to be born annually in Brazil. Most of these infected children are likely to develop symptoms or signs of clinical toxoplasmosis. Among the congenitally infected children whose clinical data are described in this review, several died soon after birth, 35% had neurological disease including hydrocephalus, microcephaly and mental retardation, 80% had ocular lesions, and in one report 40% of children had hearing loss. The severity of clinical toxoplasmosis in Brazilian children may be associated with the genetic characteristics of<jats:italic>T. gondii</jats:italic>isolates prevailing in animals and humans in Brazil.</jats:p>

Epidemiological aspects of Toxoplasma gondii infection in riverside communities in the Southern Brazilian Amazon

“…these communities, given that T. gondii infection is active in these locations. The overall prevalence of anti-T. gondii antibodies found in this study was 55.7%, and this percentage is within the range found in other Brazilian regions and in the Amazon region (2) . However, the present study was the fi rst to be conducted among riverside communities, which present peculiar habits related to the environment.…”

“…However, although all the isolates were virulent and lethal to the infected mice, conclusions regarding the virulence of these isolates cannot be made without knowing the dosage of the inoculum (18) . Nevertheless, the pathogenic profi le observed here is indicative of a high virulence, as observed with the majority of Brazilian isolates (2) (8) .…”

“…In Brazil, the burden of clinical toxoplasmosis in humans is considered to be very high, as up to 50% of elementary school children and 50-80% of women of childbearing age show antibodies against T. gondii (2) . Despite the large number of studies that have investigated the epidemiology of this agent in human beings and animals, information on the prevalence of T. gondii infection is scarce in some regions of Brazil.…”

Frequency of anti- Toxoplasma gondii IgA, IgM, and IgG antibodies in high-risk pregnancies, in Brazil

“…The severity of the disease may be associated with the type of strain acquired, the immune status of the mother, and the gestational period in which maternal infection and fetal transmission occurs (1) (2) .…”

“…Among the different types of antibodies, the anti-Toxoplasma gondii immunoglobulin G (IgG) and immunoglobulin M (IgM) are the most commonly reported among pregnant women worldwide (1) (3) , and the presence of anti-T. gondii antibodies is an important factor in determining the time of infection. IgA and IgM class antibodies are associated with recent infections (acute infection) while IgG class antibodies are associated with chronic infection (3) (4) (5) (6) .…”