Occurrence of infection with Toxoplasma gondii and factors associated with transmission in broiler chickens and laying hens in different raising systems

Abstract

Toxoplasmosis is a zoonotic disease caused by the protozoan Toxoplasma gondii. The aim of the present study was to determine the occurrence and identify the risk factors associated with transmission of T. gondii to chickens raised in different systems (free-ranged and conϐined) to produce eggs or meat. The 810 animals were allocated in two experimental groups according to the production system purpose: 460 broiler chickens (Group 1) and 350 layer chickens (Group 2). In order to analyze the possible factors involved in T. gondii infection in the chickens, an epidemiological questionnaire was developed for all properties.The serological detection of anti-Toxoplasma gondii antibodies was performed by Indirect Immunoϐluorescence (IFAT) and by Enzime Linked Imunossorbent Assay (ELISA). Since the agreement index (kappa) between these two serological techniques was considered high, 21.2% of the 810 animals were considered reactive. In Group 1, 12.2% (56/460) were positive, while in the Group 2 the positivity rate was 33.1% (116/350). The production system may be inϐluencing the seropositivity of the animals in both groups. However, only in Group 2 it was possible to notice a statistically signiϐicant relationship between the breeding system and the frequency of positive sera. This result indicates that, at least for laying hens, the production system is directly involved in T. gondii infection. The contact with cats in Group 1 did not inϐluence the distribution of seroreactive animals, but in Group 2 a signiϐicant relationship was observed. The occurrence of anti-T. gondii antibodies was high in both groups (broiler and posture chickens). Free-ranged chickens raised for egg production proved to be the most exposed group to the T. gondii infection. This can be related to the fact that these animals stay for longer periods in the farms, in direct contact with possibly contaminated soil by the presence of domestic cats.INDEX TERMS: Toxoplasma gondii, broiler chickens, laying hens, transmission.RESUMO.-[Ocorrência da infecção por Toxoplasma gondii e fatores associados à sua transmissão em aves de corte e postura produzidas em diferentes tipos de criação.] A toxoplasmose é uma zoonose causada pelo protozoário Toxoplasma gondii. O objetivo deste estudo foi determinar a ocorrência e identiϐicar os fatores de risco associados à transmissão de T. gondii para frangos criados em diferentes sistemas (caipira e conϐinado) para produzir ovos ou carne. Os 810 animais foram divididos em dois grupos experimentais de acordo com o propósito do sistema de produção: 460 frangos de corte (Grupo 1) e 350 galinhas poedeiras (Grupo 2). A ϐim de analisar os possí- symptoms of toxoplasmosis in birds, even those infected with virulent strains, are rarely reported (Hepding 1939, Fankhauser 1951, Nobrega et al. 1967, Dubey et al. 2002, Dubey et al. 2006, thus chickens are considered resistant to clinical toxoplasmosis. Torticollis, inability to stand, lateral recumbency and anorexia are clinical signs already described (Dubey et al. 2007, Dubey 201...

Sero-prevalence of Toxoplasma gondii infection in backyard poultry birds of Tarai Zone of West Bengal, India

“…Sero-prevalence (20.33%) recorded in the present study though lower than that of the earlier reports from India [16] and other parts of the world [2,8,12], in some villages more than 25% backyard poultry birds were found seropositive. The sources of human infection vary all over the world with the culture of the society, ethnicity, geographical location and food habits of the population [19].…”

“…Poultry egg is not considered as a source of infection [7] although T. gondii infection is possible in ovary and oviduct of chickens [20]. High prevalence in free-range birds might be due to their habit of scratching the earth and feeding, which facilitates easy access to the feces of cat [1,8]. Backyard poultry birds in the present study also take their feed from soil during daytime.…”

“…Several surveys have been conducted in different countries for the detection of T. gondii infection in free-range chickens and in most of the cases the prevalence ranged between 36.03% and 85.7% [2,6,8,9,12].…”

“…Several surveys in different countries have shown that sero-prevalence of T. gondii infection in poultry birds varied from moderate to high. Sero-positivity for T. gondii and isolation of the parasite have been reported in free-range chickens reared in Egypt [4], Pakistan [5], Mexico [6], Ghana, Indonesia, Italy, Poland, Vietnam [7], Brazil [8] and China [2,9].…”

Mapping of the environmental contamination of Toxoplasma gondii by georeferencing isolates from chickens in an endemic area in Southeast Rio de Janeiro State, Brazil

“…Outbreaks of human toxoplasmosis in Brazil related to the consumption of water contaminated with T. gondii oocysts have been described in Rio de Janeiro (Bahia- , Paraná (Moura et al, 2006) and Ceará (Heukelbach et al, 2007). The use of untreated water for drinking by humans and farm animals is frequent in farms from the state of Rio de Janeiro, as observed by Millar et al (2012) and in the present study. These data therefore suggest the possibility of infection of the population and animals of these areas through the consumption of water contaminated with T. gondii oocysts.…”