Presence of domesticated cats and visual impairment associated to Toxoplasma gondii serum positive children at an elementary school in Jataizinho, state of Paraná, Brazil

Socioeconomic factors associated with infection by Toxoplasma gondii and Toxocara canis in children

The intense contact of children with domestic animals or environments contaminated with faeces of these animals, together with habits related to lack of hygiene, can facilitate infection by zoonoses. The study evaluated the seroprevalence and risk factors associated with toxoplasmosis and toxocariasis in schoolchildren in the city of Jataizinho, Paraná. Of the 412 children aged 4-15 years, 56.8% (234/412) presented antibodies reactive to Toxoplasma gondii, 42.5% (175/412) presented antibodies reactive to Toxocara canis, and 27.4% (113/412) were reactive for the two species. The analysis of risk factors showed that prevalence of toxoplasmosis and toxocariasis was associated with the level of education of the child's mother (less than eight years of schooling), age range (10-15 years) and the presence of cats in the residence. In addition, family income (up to a minimum wage), presence of a dog, the habit of playing in soil/sand and eosinophilia were associated with Toxocara canis infection. There was an association between the two zoonoses (p < .01), indicating the existence of coinfection. The results show high prevalence of these two important zoonoses, alerting to the need of implementing control measures in order to reduce the incidence and risks of sequelae in children.

Early immune responses and parasite tissue distribution in mice experimentally infected with oocysts of either archetypal or non-archetypal genotypes of Toxoplasma gondii

In most of the world Toxoplasma gondii is comprised of archetypal types (types I, II and III); however, South America displays several non-archetypal strains. This study used an experimental mouse model to characterize the immune response and parasite kinetics following infection with different parasite genotypes. An oral inoculation of 50 oocysts per mouse from T. gondii M4 type II (archetypal, avirulent), BrI or BrIII (non-archetypal, virulent and intermediate virulent, respectively) for groups (G)2, G3 and G4, respectively was used. The levels of mRNA expression of cytokines, immune compounds, cell surface markers and receptor adapters [interferon gamma (IFNγ), interleukin (IL)-12, CD8, CD4, CD25, CXCR3 and MyD88] were quantified by SYBR green reverse transcription-quantitative polymerase chain reaction. Lesions were characterized by histology and detection by immunohistochemistry established distribution of parasites. Infection in G2 mice was mild and characterized by an early MyD88-dependent pathway. In G3, there were high levels of expression of pro-inflammatory cytokines IFNγ and IL-12 in the mice showing severe clinical symptoms at 8–11 days post infection (dpi), combined with the upregulation of CD25, abundant tachyzoites and tissue lesions in livers, lungs and intestines. Significant longer expression of IFNγ and IL-12 genes, with other Th1-balanced immune responses, such as increased levels of CXCR3 and MyD88 in G4, resulted in survival of mice and chronic toxoplasmosis, with the occurrence of tissue cysts in brain and lungs, at 14 and 21 dpi. Different immune responses and kinetics of gene expression appear to be elicited by the different strains and non-archetypal parasites demonstrated higher virulence.

Congenital Transmission of Toxoplasma gondii After Experimental Reinfection With Brazilian Typical Strains in Chronically Infected Sheep

Toxoplasma gondii is a cause of congenital diseases, miscarriages and stillbirths in production animals. In Brazil, non-archetypal genotypes of the parasite may be related to severe disease. Experimental infection with T. gondii was studied in sheep to analyse congenital transmission-related parameters in reinfections with different Brazilian parasite strains. Thirteen T. gondii-seronegative sheep were orally infected with 2 × 10³oocysts for the primary infection: G1 (4 animals) were inoculated with TgCatBr71 strain (Type BrI genotype) and G2 andG3 (5 and 4 animals, respectively) withTgCatBr60 strain (Type BrIII genotype). After chronification of infection, the animals were impregnated. A second infection was performed after 60 days of gestation. TheG1 andG3 animals were inoculated withTgCatBr60BrIII and the G2 animals withTgCatBr71 BrI oocysts. The effects of reinfection were compared with a control group (5 animals) through physical examination, ultrasound imaging and serology. Ovine experimental infections were evaluated using mouse bioassays, molecular analysis, serological tests, histopathology, and immunohistochemistry. No abortions occurred; a seropositive lamb and a mummified fetus from G2-BrIIIxBrI were produced. The vertical transmission rate detected in lambs from chronically infected sheep was 31.6% (6/19). It is demonstrated that reinfection and subsequent congenital transmission occured in one sheep with a primary Brl infection challenged with BrIII genotype of T. gondii. In a twin pregnancy from G2-BrIIIxBrI, congenital transmission from a latent infection was detected in both lambs. Congenital transmission could not be tracked in three lambs. Overall, previous T. gondii infection may fail to protect against congenital transmission from a reinfection and primary infection induced insufficient protection against vertical transmission which must be taken into account in decision-making for the use of seropositive animals as breeders. Similar trials with larger groups and contemplating host cellular immune response studies should be conducted to evaluate the actual impact of T. gondii reinfection involving different strains in sheep.

SEROEPIDEMIOLOGY OF TOXOPLASMOSIS IN HUMANS AND DOGS FROM A SMALL MUNICIPALITY IN PARANA, BRAZIL

Abstract Toxoplasmosis is a worldwide zoonosis with important public health implications. The aims of this study were to determine and identify factors associated to the seroprevalence of anti-Toxoplasma gondii antibodies in humans and dogs from Jataizinho, Parana State, Brazil. Serum samples from 280 humans and 766 dogs, from rural and urban areas, were tested by indirect immunofluorescent antibody test. Positive dilutions were ≥ 1:16. Epidemiological informations were obtained through an individual questionnaire and data tabulation was performed using EpiInfo 3.5.3 (CDC, Atlanta). Statistical significance was evaluated by chi-square (ᵪ2) or Fisher's exact tests with a 5.0 % significance level. The seroprevalence in humans was 70.00% (196/280), as follows: 69.08% (143/207) in rural and 72.60% (53/73) in a slum urban community. The seroprevalence in dogs was 52.35% (401/766), as follows: 71.74% (99/138) in rural and 48.08% (302/628) in urban area. In rural areas, there was no factor associated to risk of infection. In urban slum community, visualizing more than four rats at home was a factor statistically associated to seropositivity for human toxoplamosis. Infection of urban dogs was associated to age, contact with stray dogs or rodents, and free access to street. The results indicated a similar possibility of contact with Toxoplasma gondii between dogs and humans living in rural or slum urban areas of small municipalities.

Latent Toxoplasma gondii Infection and Associated Risk Factors among HIV-Infected Individuals at Arba Minch Hospital, South Ethiopia

Toxoplasmosis is a parasitic disease caused by Toxoplasma gondii (T. gondii). The parasite has cosmopolitan distribution, infecting almost all species of warm-blooded animals. Latent T. gondii infection in HIV/AIDS patients is a risk for development of cerebral toxoplasmosis (CT). The aim of this study is to determine seroprevalence of latent T. gondii infection and assess its associated factors among individuals infected with HIV in Arba Minch Hospital, south Ethiopia. A facility-based cross-sectional study involving 170 HIV-infected individuals attending Arba Minch Hospital antiretroviral therapy (ART) clinic was conducted from April to June 2013. Data on demographic profile of the study participants and factors associated with T. gondii infection were gathered using a questionnaire. Serum was tested for IgG anti-T. gondii antibody by enzyme-linked immunosorbent assay (ELISA). Data were analyzed using SPSS version 20 software. Seroprevalence of latent T. gondii infection among the study participants was 88.2%. Consumption of raw meat (AOR = 4.361; 95% CI: 1.409-13.496) and involvement in farming/gardening activities (AOR = 4.051; 95% CI: 1.112-14.758) were independent predictors of T. gondii seropositivity. This study revealed high prevalence of latent T. gondii infection, similar to other studies. Monitoring of the patients to prevent reactivation of the latent T. gondii infection is recommended.

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

Infections by the protozoan parasite Toxoplasma gondii 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 T. gondii 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 T. gondii infection in humans. Up to 50% of elementary school children and 50-80% of women of child-bearing age have antibodies to T. gondii. 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 T. gondii 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 T. gondii isolates prevailing in animals and humans in Brazil.