First study on seroepidemiology and isolation of Toxoplasma gondii in free-range chickens in the semi-arid region of Paraíba state, Brazil

Abstract

The aim of this study was to investigate the seroprevalence and isolation of Toxoplasma gondii in free-range chickens in the state of Paraíba, northeastern Brazil. For this, blood samples were collected from 483 chickens in five municipalities in the state of Paraíba. The indirect immunofluorescence assay for anti-T. gondii antibodies was performed. The seropositive birds were slaughtered, and their brains and hearts were collected in order to perform a bioassay in mice. An epidemiological questionnaire was applied on the smallholdings visited, and univariable and multivariable logistic regressions were used to evaluate risk factors. The prevalence of chickens seropositive for T. gondii was found to be 31.5 % (152/483), and 86.1 % (56/65) of the smallholdings were positive. Among the 71 chickens subjected to bioassaying in mice, isolates of T. gondii were obtained from 33 (46.5 %). The isolates were named TgCkBrPB1 to 33. It was observed that the higher the chickens' antibody titer was, the greater the chance of isolating the parasite also was. Sixteen of the 33 isolates (48.5 %) were lethal for all the mice inoculated until 30 days post-inoculation. The risk factors for infection with T. gondii among these free-range chickens were extensive and semi-extensive rearing systems, smallholdings located in urban areas, and presence of cats. The results indicate that the prevalence of T. gondii among chickens in the state of Paraíba is high. Many parasites remained viable in the tissues of the birds studied, and presence of the protozoan was directly related to the management of these birds.

Cross-sectional survey for toxoplasmosis in free-range chickens (Gallus gallus domesticus) from the Atlantic Forest area in Alagoas state, Northeastern Brazil

“…However, the properly standardized IFAT can produce high sensitivity and specificity, being a reproducible option when available, and very effective using cut-off ≥16 in field studies in chickens. The prevalence rate in the current study was higher compared to most of the recent surveys carried out in Brazil, with the reported rates varying from 17.2% to 31.5% (Feitosa et al, 2016;Millar et al, 2012;Sá et al, 2017), which indicates that, compared to intensive industrial systems, T. gondii is more wide-spread in free-range systems and soil is probably the main source of oocysts. Furthermore, the chickens have a shorter life span in the industrial systems and contact with cats and contaminated soil is less likely in this scenario (Liu et al, 2017).…”

“…In addition, free-range chickens have an epidemiological significance because raw or undercooked chicken meat is a major source of infection for humans and other animals, if consumed or handled without proper hygiene (Casartelli-Alves et al, 2015). Moreover, it is worth mentioning that in previous studies T. gondii was isolated from free-range chickens in Northeastern Brazil and in the municipality investigated in this study (Clementino Andrade et al, 2013;Feitosa et al, 2016;Santos Silva et al, 2020).…”

“…This fact may be related to the consumption habits of the owners because in Brazil, eating undercooked meat and feeding animals with leftover meat and raw viscera is a common practice (Sá et al, 2017). In these cases, rectification and improvement 5/6 T. gondii in free-range chickens, Northeast Brazil of management systems is an alternative method, which can be employed to reduce the frequency of the disease in backyard farms (Feitosa et al, 2016).…”

<i>Toxoplasma gondii</i> molecular and immunological identification and risk factors associated with infection in chicken slaughtered at Triângulo Mineiro region, Minas Gerais, Brazil

“…The predominance of infection in older chickens compared with that in younger ones is in part likely to be due to an increase in the cumulative effect of exposure to the parasite by adult animals, that is, with the increase in the age of a bird, the likelihood of it becoming infected by T. gondii oocysts present in the environment also increases (DUBEY, 2010b). Although the number of females slaughtered was higher than that of males, no association was found between seropositivity for T. gondii and the sex of the chickens, corroborating the findings of Bonna et al (2006) and Feitosa et al (2016).…”

“…This result suggests these animals were more exposed to environmental contamination by the oocysts, thus confirming the role of birds as indicators of environmental contamination by T. gondii. Feitosa et al (2016) did not show an association between these two variables when chickens from five municipalities in the state of Paraíba were analyzed. Despite the researchers had not shown statistic association, the percentage of positive hens fed with ration and pasture was higher than that of those fed exclusively with ration.…”