No abstract

Soroepidemiologia da infecção pelo Toxoplasma gondii no Município de Novo Repartimento, Estado do Pará, BrasilSeroepidemiology of Toxoplasma gondii infection in the City of Novo Repartimento, Pará State, Brazil Seroepidemiología de la infección por Toxoplasma gondii en el Municipio de Novo Repartimento, Estado de Pará, Brasil RESUMO Toxoplasmose é uma infecção zoonótica causada pelo Toxoplasma gondii, um protozoário de ocorrência mundial que pode infectar aves e mamíferos, incluindo humanos. A soroprevalência da infecção varia de acordo com a região, sendo considerada alta no Brasil. No Estado do Pará, a maioria dos estudos está restrita à área urbana da Cidade de Belém, onde os índices são superiores a 70%. Os objetivos do presente estudo foram estimar a soroprevalência em uma área rural do Estado e identificar os fatores de risco associados à infecção. Estudo descritivo e transversal foi conduzido na população do Município de Novo Repartimento, sudeste do Pará. Foram incluídos no estudo 427 indivíduos randomicamente escolhidos na demanda do laboratório de análises clínicas do Município. As amostras de soro foram analisadas por reação de imunofluorescência indireta para detecção de IgG e IgM anti-T. gondii. De cada indivíduo, foram obtidas informações sociodemográficas e epidemiológicas para avaliar as variáveis em relação à soropositividade. A soroprevalência observada para IgG foi de 81,26% e 0,70% para IgM. As variáveis estatisticamente associadas com a infecção pelo T. gondii foram o contato com gatos fora do domicílio e o consumo de carne de animais silvestres (caça). Os dados obtidos demonstram a alta soroprevalência de toxoplasmose em uma área rural do Estado do Pará, onde características associadas com hábitos alimentares e comportamentais da população local favorecem o desenvolvimento e a transmissão do T. gondii.

The relevance of consuming raw or undercooked beef in the transmission of toxoplasmosis is unclear due to the high resistance of cattle to infection. However, this possibility needs to be considered in endemic areas, such as the Amazon, where the consumption of beef is frequent. The objective of this study was to determine the frequency of anti-Toxoplasma gondii IgG antibodies in beef cattle slaughtered in the metropolitan region of Belem, Pará state, Brazil. Blood samples were collected from 500 animals of both genders in a licensed slaughterhouse in Belém. Anti-T. gondii IgG antibodies were detected by an indirect immunofluorescence assay (IFA) with a cut-off titer of 1:64. Anti-T. gondii antibodies were found in 203 animals (40.6%), with a titer of 64 in 112 animals (55.2%), 128 in 68 animals (33.5%), 256 in 15 animals (7.4%), 512 in 5 animals (2.5%), and 1,024 in 3 animals (1.4%). No significant difference was observed between males and females (p > 0.05). The high frequency of anti-T. gondii antibodies observed in beef cattle slaughtered in Belém indicates that the meat of these animals may be an important source of infection for humans and carnivorous domestic animals when inadequately cooked beef is consumed.

Ocular infection with Toxoplasma gondii causes toxoplasmosis in mice. However, following ocular infection with tachyzoites, the cause of the accompanying progressive changes in hippocampal-dependent tasks, and their relationship with the morphology and number of microglia, is less well understood. Here, in 6-month-old, female BALB/c mice, 5 μl of a suspension containing 48.5 × 106 tachyzoites/ml was introduced into the conjunctival sac; control received an equal volume of saline. Before and after instillation, all mice were subject to an olfactory discrimination (OD) test, using predator (cat) feces, and to an open-field (OF) task. After the behavioral tests, the animals were culled at either 22 or 44 days post-instillation (dpi), and the brains and retinas were dissected and processed for immunohistochemistry. The total number of Iba-1-immunolabeled microglia in the molecular layer of the dentate gyrus was estimated, and three-dimensional reconstructions of the cells were evaluated. Immobility was increased in the infected group at 12, 22, and 43 dpi, but the greatest immobility was observed at 22 dpi and was associated with reduced line crossing in the OF and distance traveled. In the OD test, infected animals spent more time in the compartment with feline fecal material at 14 and at 43 dpi. No OD changes were observed in the control group. The number of microglia was increased at 22 dpi but returned to control levels by 44 dpi. These changes were associated with the differentiation of T. gondii tachyzoites into bradyzoite-enclosed cysts within the brain and retina. Thus, infection of mice with T. gondii alters exploratory behavior, gives rise to a loss in predator’s odor avoidance from 2 weeks after infection, increased microglia number, and altered their morphology in the molecular layer of the dentate gyrus.