Evaluation of the viability of sporulated oocysts of Neospora caninum under different temperature and disinfectants treatments / Avaliação da viabilidade de oocistos esporulados de Neospora caninum a diferentes condições de temperatura e ação de desinfetantes

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Neospora caninum is an Apicomplexan parasite that causes neuromuscular disorders in dogs and abortion in cattle. Dogs and coyotes are the only species identified as definitive hosts. The sexual phase of the N. caninum life cycle occurs within the host, and results in the shedding of oocysts in the feces that will sporulate in the environment and become infective. Despite their relevance as a source of infection for a number of different hosts, the resistance and viability of such oocysts to physical and chemical treatments are yet to be known. The purpose of this study was to assess the viability of N. caninum sporulated oocysts after exposure to treatments using different disinfectants, temperatures and periods of time. For acquisition of the oocysts, three dogs were fed brain tissue from buffaloes positive for antibodies to N. caninum by an indirect fluorescent antibody test (IFAT 100). Only one of the dogs excreted Neospora-Hammondia type oocysts. Such oocysts were confirmed to be N. caninum by bioassay in gerbils and molecular methods (PCR-RFLP). The sporulated oocysts were purified and 11 doses with approximately 3,000 oocysts each were treated as follows: 10% formaldehyde (formol) for 1 h; 10% ammonia for 1 h; 70% alcohol for 1 h; absolute alcohol for 1 h; 2% iodine for 1 h; 10% sodium hypochlorite for 1 h; Room temperature, control; -20ºC for 6 h; 4ºC for 6 h; 60ºC for 1 min, and 100ºC for 1 min. All chemical treatments were performed at room temperature. After treatment, the oocysts were divided into doses of 1,000 oocysts each and administered into three gerbils (Meriones unguiculatus) orally (1,000 oocysts per gerbil) per treatment. The gerbils were euthanized after 63 days. Blood samples were taken to be tested for the presence of N. caninum antibodies (IFAT and Western blotting analysis), and tissues samples to be tested for the presence of cysts by brain smear technique and detection of the parasite DNA (real-time PCR), and the identification of the parasite by immunohistochemical and histopathological examinations. In order to be considered an effective treatment, negative results should be observed in the gerbils of all five evaluations conducted. Out of the treatments carried out in this study, exposures to a temperature of 100ºC for 1 min and to a 10% sodium hypochlorite solution for 1 h were effective.

ASSUNTO(S)

controle oocysts coccidiose coccidiosis desinfetantes neospora caninum oocistos neospora caninum disinfectants control

ACESSO AO ARTIGO

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