Toxoplasma gondii infection in Brazilian domestic outpatient cats

The occurrence of Toxoplasma antibodies in domestic outpatient cats in the city of São Paulo was evaluated using the indirect immunofluorescence assay. A total of 248 blood samples obtained from male and female cats seen at the Veterinary Teaching Hospital at the University of São Paulo between February 1996 and January 1997 were tested. Of these, 17.7% were positive, with a 64 titer being detected in most animals. The frequence of Toxoplasma antibodies was significantly higher in older cats, those fed raw meat and those with free access to the outdoor environment. There was no significant difference in reactivity between males and females. We conclude that diet and free access to the outdoor environment were equally important as predisposing factors to the risk of Toxoplasma infection.

Seroprevalence of Toxoplasma gondii infection among indian people living in Iauareté, São Gabriel da Cachoeira, Amazonas, Brazil

The goal of this survey was to estimate the seroprevalence of Toxoplasma gondii infection in Iauareté, a multiethnic Indian community in the upper Rio Negro basin. We carried out a cross-sectional survey (n = 260), in order to obtain serum samples and demographic data. The sample was randomly selected, by family conglomerate analysis. Serodiagnosis was performed by an enzyme-linked immunosorbent assay and indirect immunofluorescence. Prevalence of reactivity was 73.5% (191/260), being higher in the older-age groups, reaching 95.7% (44/46) in the group aged 50 years or more. The majority of seropositive subjects had titers equal to or less than 1:64. Seroprevalence was greater in Indians belonging to the Hupda ethnic group (p = 0.03). According to the present survey, Indian people living in Iauareté have a high prevalence of antibodies to T. gondii. Demographic concentration and urbanization within low sanitation and poor hygiene backgrounds, as well as unfiltered water consumption, may be related to the high frequency of T. gondii seroprevalence observed in the studied area.

Prevalence and risk factors for Toxoplasma gondii infection among pregnant and postpartum women attended at public healthcare facilities in the City of Niterói, State of Rio de Janeiro, Brazil

IntroductionTo determine the prevalence of immunoglobulin G (IgG) and immunoglobulin M (IgM) anti-Toxoplasma gondii antibodies among pregnant and postpartum women attended within the public healthcare system in Niterói, State of Rio de Janeiro, and to detect possible exposure factors associated with T. gondii infection in this population.MethodsIgM and IgG anti-T. gondii antibodies were investigated in 276 pregnant and 124 postpartum women by using the indirect immunofluorescence (IFAT) and immunoenzymatic assay (ELISA) techniques. The participants were selected by convenience sampling. All these 400 patients filled out a free and informed consent statement, answered an epidemiological questionnaire and were informed about the disease.ResultsAmong the 400 samples analyzed, 234 (58.5%) were reactive to IgG anti-T. gondii antibodies, according to the IFAT and/or ELISA assay. One pregnant woman was found to be reactive to IgM anti-T. gondii antibodies, with an intermediate IgG avidity test. Risk factor analysis showed that seropositivity was significantly associated (p<0.05) with age, contact with cats and presence of rodents at home. Through a logistic regression model, these associations were confirmed for age and contact with cats, while education at least of the high school level was found to be a protective factor.ConclusionsThe prevalence rate of IgG anti-T. gondii antibodies in the City of Niterói was high and the risk factors for infection detected after multivariate analysis were: age over 30 years, contact with cats and education levels lower than university graduate level.

Toxoplasma gondii infection: seroprevalence and associated risk factors among primary schoolchildren in Lagos City, Southern Nigeria

INTRODUCTION: Toxoplasma gondii infection has been described as the most widespread zoonotic infection of humans and other animals. Information concerning T. gondii infection among schoolchildren is unavailable in Lagos City, Nigeria. METHODS: This cross-sectional study investigated the seroprevalence and risk factors associated with T. gondii infection among primary schoolchildren (PSC) from a community located in the center of Lagos, southern Nigeria, from November 2013 to March 2014. A total of 382 PSC were screened for the presence of sera anti-T. gondii antibodies using a latex agglutination test (TOXO Test-MT, Tokyo, Japan). A cutoff titer of ≥ 1:32 was considered positive, while titers ≥ 1:1,024 indicated high responders. Questionnaires were also used to obtain data on possible risk factors from parents/guardians. RESULTS: The overall seroprevalence was 24% (91/382), and 83.5% (76/91) of seropositive PSC were classified as high responders. Among the risk factors tested, including contact with cats and soil, consumption of raw meat and vegetables, and drinking unboiled water, none showed statistical significance after multivariate adjustment. No associations were observed among age, gender, body mass index (BMI), and parents' occupation/educational level. CONCLUSIONS: The findings in this study show evidence of active infection, and hence, there is need for urgent preventive measures in this city. Further investigation is required to clarify the transmission routes. Policy makers also need to initiate prevention and control programs to protect pregnant women and immunocompromised patients in particular because they are more severely affected by T. gondii infection.

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

INTRODUCTION: Toxoplasma gondii infection is widely prevalent in humans and other animals worldwide. Information on the prevalence of T. gondii infection is scarce in some regions of Brazil, including riverside communities along the Amazon River basin. M METHODS: The prevalence of T. gondii in 231 people, aged 1-85 years, who were living in four riverside communities along the Purus River, Lábrea, State of Amazonas, Brazil, was determined. Antibodies against T. gondii were assayed using a commercial enzyme-linked immunosorbent assay (ELISA) kit. The hearts and brains of 50 chickens, which were raised free-range in the communities, were pooled according to the community of origin and bioassayed in mice. The isolates were genotyped using polymorphisms at 12 nuclear markers (SAG1, 5' and 3'-SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico and CS3). RESULTS: The overall seroprevalence of T. gondii was 56.7% (131/231). IgG antibodies were presented by 117 (89.3%) and IgM by 14 (10.7%) of the 131 positive individuals. No association between age group and gender with prevalence was observed (chi-square test, p > 0.05); however, the comparison between localities showed that the seroprevalence of T. gondii was significantly lower among the individuals living in the Boca do Ituxi (p < 0.05) community. Five isolates of T. gondii were obtained in the mouse bioassay, and genotyping revealed two complete genotypes that had not been described previously and three mixed isolates. CONCLUSIONS: These results support previous findings that T. gondii population genetics are highly diverse in Brazil and that T. gondii infection is active in these riverside communities.

Risk factors for Toxoplasma gondii infection among pregnant women from the State of Tocantins, Northern Brazil

ABSTRACT INTRODUCTION: The prevalence of infection by Toxoplasma gondii and associated risk factors in pregnant women in Tocantins, Northern Brazil were assessed. METHODS: Serological analysis was performed in 338 serum samples and an oral questionnaire was utilized to identify potential risk factors. RESULTS: Anti-IgG antibodies against T. gondii were detected in 71% (240/338) of the pregnant women. Prior contact with cats and meat handling were found to be associated with T. gondii infection. CONCLUSIONS: A considerable percentage (29%) of women living in the Tocantins area remain susceptible to infection by the T. gondii protozoon, representing a serious public health risk.

Seroprevalence of Toxoplasma gondii infection in goats by the indirect haemagglutination, immunofluorescence and immunoenzymatic tests in the region of Uberlândia, Brazil

A comparative study of the indirect haemagglutination (IHA), immunofluorescence (IFAT) and immunoenzymatic (ELISA) tests was carried out to determine the prevalence of Toxoplasma gondii antibodies in goats. One hundred seventy-four serum samples were obtained from four goat herds from the region of Uberlândia, State of Minas Gerais. The distribution of the animals, according to their origin, was as follow: 71 from herd I; 39 from herd II; 37 from herd III; and 27 from herd IV. Serum samples were analyzed by IHA, IFAT and ELISA, considering the reactivity of the serum samples at dilution ≥ 1:64 as cut off titer for the three tests. A global seroprevalence of 18.4% was observed, with significantly higher positivity rate in the herd II (66.7%) and older animals (> 36 months). A high and significant positive correlation was found between the titers obtained by the IHA versus IFAT, IHA versus ELISA, and ELISA versus IFAT. Therefore, it can be concluded that the three analyzed tests have shown to be highly concordant and appropriate for epidemiological surveys of Toxoplasma infection in goats. Although the seroprevalence of T. gondii infection in goats is relatively low in this region as compared to other regions of the country, adequate management might be useful and essential to control the infection in the goat herds.

Toxoplasma gondii infection induces lipid metabolism alterations in the murine host

Host lipids have been implicated in the pathogenesis of Toxoplasma gondiiinfection. To determine if Toxoplasmainfection influences the lipid status in the normal host, we assessed serum lipids of Swiss-Webster mice during infection with the BGD-1 strain (type-2) at a series of time points. Mice were bled at days zero and 42 post-infection, and subgroups were additionally bled on alternating weeks (model 1), or sacrificed at days zero, 14 and 42 (model 2) for the measurement of total cholesterol (Chl), high density lipoproteins (HDL), low density lipoproteins (LDL) and triglycerides and adiponectin. At day 42, brains were harvested for cyst enumeration. A significant decrease (p = 0.02) in HDL and total Chl was first noted in infected vs. control mice at day 14 and persisted to day 42 (p = 0.013). Conversely, LDL was unaltered until day 42, when it increased (p = 0.043). Serum LDL levels at day 42 correlated only with cyst counts of above 300 (found in 44% mice), while the change in HDL between days zero and 42 correlated with both the overall mean cyst count (p = 0.041) and cyst counts above 300 (p = 0.044). Calculated per cyst, this decrease in HDL in individual animals ranged from 0.1-17 µmol/L, with a mean of 2.43 ± 4.14 µmol/L. Serum adiponectin levels remained similar between infected and control mice throughout the experiment.

Single nucleotide polymorphisms in the interferon gamma gene are associated with distinct types of retinochoroidal scar lesions presumably caused by Toxoplasma gondii infection

The association of single nucleotide polymorphisms (SNPs) in the interferon (IFN)-γ gene ( IFNG ) with different types of retinal scar lesions presumably caused by toxoplasmosis were investigated in a cross-sectional population-based genetic study. Ten SNPs were investigated and after Bonferroni correction, only the associations between SNPs rs2069718 and rs3181035 with retinal/retinochoroidal scar lesions type A (most severe scar lesions) and C (least severe scar lesions), respectively, remained significant. The associations of two different IFNG SNPs with two different types of retinal lesions attributable to toxoplasmosis support the hypothesis that different inflammatory mechanisms underlie the development of these lesions. The in vitro analysis of IFN-γ secretion by peripheral blood mononuclear cells stimulated with Toxoplasma gondii antigens was also investigated. The association between SNP rs2069718 and type A scar lesions revealed that differential IFN-γ levels are correlated with distinct genotypes. However, no correlation was observed with IFN-γ secretion levels and the SNP rs3181035 , which was significantly associated with type C scar lesions. Our findings strongly suggest that immunogenetic studies of individuals with congenital or postnatally acquired infection are needed to better understand the role of IFN-γ and its polymorphisms in the pathogenesis of ocular toxoplasmosis.

Risk factors associated with Toxoplasma gondii infection in dairy cattle, state of Rio de Janeiro

Toxoplasmosis is one of the most common parasitic zoonoses throughout the world. Infection in man and animals varies in different geographical areas influenced by many environmental conditions. Seroprevalence of Toxoplasma gondii infection in cattle in Brazil ranges from 1.03 to 71%. A cross-sectional survey was carried out in 58 out of 453 farms in the South Fluminense Paraiba Valley, State of Rio de Janeiro, Brazil. Over 3-year-old cattle (n=589) from dairy herds were selected for blood collection and detection of anti-T. gondii antibodies by indirect immunofluorescence reaction (IFA) with initial titration of 1:16; titers > 64 were considered positive. Univariate analysis of risk factors showed that cats in contact with cattle, cats in contact with drinking water, and number of cats were associated with T. gondii seroprevalence. Logistic regression revealed a two-fold increased risk for infection of cattle (p=0.0138) through larger number of cats (>3) compared with low numbers of cats (1-2) on the farm. In contrast, the presence of chickens was considered a protective factor (p=0.025).

Occurrence and risk factors associated with infection by Toxoplasma gondii in goats in the State of Alagoas, Brazil

INTRODUCTION: Goats are considered very susceptible to infection by Toxoplasma gondii and when this occurs during pregnancy, it may cause fetal death with subsequent fetal resorption, abortion, mummification, stillborn or the birth of weak goats. The objective of this work was to determine the occurrence of and identify risk factors for T. gondii infection in goats in different mesoregions in the State of Alagoas. METHODS: The research was conducted on 24 goat breeding farms in 10 municipalities. A total of 454 blood samples were examined for anti-T. gondii antibodies by indirect immunofluorescence antibody test. To evaluate the risk factors of toxoplasmosis in goats, questionnaires were applied analyzing the farm's production system and nutritional, reproductive and sanitary management. RESULTS: Disease occurrence was 39% with 95.8% of farms presenting seropositive animals. Significant associations were observed for mesoregion (OR = 0.23; 95%CI = 0.09 - 0.57), age (OR = 0.36; 95%CI = 0.20 - 0.64), semi-intensive herd management (OR = 8.70; 95%CI = 1.87 - 40.43), access of cats to water provided for goats (OR = 3.38; 95%CI = 1.89-6.02) and cats feeding on placental remnants (OR = 2.73; 95%CI = 1.38 - 5.40). CONCLUSIONS: Toxoplasma gondii infection is disseminated in the State of Alagoas and the adoption of a program that monitors infection foci is required to reduce the risk factors identified in the present study.

Effects of infection with Toxoplasma gondii oocysts on the intestinal wall and the myenteric plexus of chicken (Gallus gallus)

This paper aims to analyze the effects of the Toxoplasma gondii infection in the intestinal wall and myenteric plexus of chicken (Gallus gallus). Ten 36-day-old chickens were separated into two groups: control and experimental, orally inoculated with oocysts of the T. gondii strain M7741 genotype III. After 60 days the birds were submitted to euthanasia and had their duodenum removed. Part of the intestinal segments was submitted to histological routine, HE staining, PAS histochemical technique, and Alcian Blue. Qualitative analysis of the intestinal wall and comparative measurements among the groups with respect to total wall thickness, muscle tunic, mucosa, and tunica mucosa were carried out. Caliciform cells were quantified. The other part of the intestinal segments was fixed in formol acetic acid and dissected having the tunica mucosa and the tela submucosa removed. Neurons were stained with Giemsa, counted, and measured. Chickens from the experimental group presented diarrhea and inflammatory infiltrates in the tunica mucosa, thickness reduction of all the parameters assessed in the intestinal wall, and an increase of the number of caliciform cells. There was a ~70% reduction regarding the intensity of myenteric neurons; and the remaining cells presented a reduction of ~2.4% of the perikarion and ~40.5% of the nucleus (p<0.05). Chronic infection induced by T. gondii oocysts resulted in intestinal wall atrophy, mucin secretion increase, death and atrophy of chicken myenteric plexus neurons. Death and atrophy of myenteric plexus neurons may be related with the causes of diarrhea observed in chickens with toxoplasmosis.

Prevalence of IgG antibodies specific to Toxoplasma gondii among blood donors in Recife, Northeast Brazil

A serological survey of Toxoplasma gondii infection in blood donors was carried out in order to identify seroprevalence in Recife, Brazil. Sera from 160 individuals (119 male and 41 female) were evaluated by using a Toxoplasma IgG-antibody enzyme immunoassay (Denka Seiken Co., LTD., Tokyo, Japan). The seropositive percentual for males (79.0%) showed to be higher (p < 0.05) than for females (63.4%). This percentage increases with age, ranging from 18.2% to 92.6% for individuals aging under 20 and 40-50 years old, respectively. For women of childbearing age (18-40 years) it was found a prevalence of 51.6%.

Lacrimal secretory IgA in active posterior uveitis induced by Toxoplasma gondii

It is quite difficult to diagnose active toxoplasmosis in patients with ocular toxoplasmosis. Active posterior uveitis presumably due to Toxoplasma gondii infection (APUPT) is seldom produced during a prime-infection; hence most patients do not show high IgM antibodies. High levels of IgA have been described in active toxoplasmosis. The purpose of this study was to investigate possible association between APUPT and the specific anti-parasite sIgA in tears. The study was carried out as case-control. Tears of 25 clinically confirmed APUPT patients and 50 healthy control subjects were analyzed. All were IgG seropositive. Specific sIgA was determined by ELISA assay using T. gondii RH strain crude extract. Anti-T. gondii sIgA was found in 84% of the cases and in 22% of the control subjects. The intensity of the reaction was higher in APUPT cases (P = 0.007). There was strong association between APUPT patients and lacrimal sIgA (odds-ratio 18.61, P = 0.0001). ELISA test sensitivity was 84% and specificity 78% . Our data suggest that anti-T.gondii secretory IgA found in tears may become an important marker for active ocular toxoplasmosis.

Toxoplasma gondii and the Immunity-Related GTPase (IRG) resistance system in mice: a review

The Immunity Related GTPases (IRG proteins) constitute a large family of interferon-inducible proteins that mediate early resistance to Toxoplasma gondii infection in mice. At least six members of this family are required for resistance of mice to virulent T. gondii strains. Recent results have shown that the complexity of the resistance arises from complex regulatory interactions between different family members. The mode of action against T. gondii depends on the ability of IRG proteins to accumulate on the parasitophorous vacuole of invading tachyzoites and to induce local damage to the vacuole resulting in disruption of the vacuolar membrane. Virulent strains of T. gondiiovercome the IRG resistance system, probably by interfering with the loading of IRG proteins onto the parasitophorous vacuole membrane. It may be assumed that T. gondii strains highly virulent for mice will be disadvantaged in the wild due to the rapid extinction of the infected host, while it is self-evident that susceptibility to virulent strains is disadvantageous to the mouse host. We consider the possibility that this double disadvantage is compensated in wild populations by segregating alleles with different resistance and susceptibility properties in the IRG system.