Seroprevalence, spatial analysis and risk factors of infection with Neospora caninum in cattle in Brazil's northern Pantanal wetland.

Ana Carolina Schmidt,Rísia Lopes Negreiros,Anderson Castro Soares De Oliveira,Richard De Campos Pacheco,Janice Elena Ioris Barddal,Daniel Moura De Aguiar,Thábata Dos Anjos Pacheco

doi:10.1590/s1984-296120180058

Abstract

Neosporosis is caused by an obligate intracellular protozoan, Neospora caninum . It is considered one of the most widespread and frequent causes of abortion in cattle worldwide. To evaluate the prevalence of anti-N. caninum antibodies and associated risk factors, serum samples were collected from 2,452 bovines at 262 farms in the northern Pantanal, state of Mato Grosso, Brazil. Each farmer was asked to fill out a questionnaire for subsequent epidemiological data analysis. Anti-N. caninum antibodies were detected by means of the indirect immunofluorescent assay (IFA), using a cut-off dilution of 1:100. The overall anti-N. caninum antibodies prevalence was 25.44% (Confidence Interval - CI 95%; 20.10%; 30.78%), and the anti-N. caninum antibodies prevalence per herd was 76.72% (CI 95%; 71.60%; 81.84%). The presence of dogs, occurrence of abortion in cows, and sale of cattle for breeding were statistically associated with seropositivity in herds, while the risk of females being seropositive for N. caninum was higher in animals ≤ 6-years-old and in the presence of dogs. A spatial analysis indicated that the relative risk of the disease is spatially constant and that the farms with the highest prevalence of anti-N. caninum antibodies are located south of the region under study.

Highlights

Neosporosis is one of the most widespread and frequent causes of bovine abortion and stillbirths around the world (MCALLISTER, 2016), leading to huge economic losses (REICHEL et al, 2013)
This study focused on an investigation into the presence of anti-N. caninum antibodies in bovines and in the identification of associated factors that affect anti-N. caninum antibodies prevalence in cattle herds in the northern Pantanal wetland of Mato Grosso state, Brazil
After the model was applied, three variables were found to be significantly associated with the prevalence of anti-N. caninum antibodies on the farms: the presence of dog, a history of abortion in the preceding 12 months, and the sale of cattle for breeding

Summary

Introduction

Neosporosis is one of the most widespread and frequent causes of bovine abortion and stillbirths around the world (MCALLISTER, 2016), leading to huge economic losses (REICHEL et al, 2013). This disease is caused by an obligate intracellular protozoan, Neospora caninum, which belongs to the phylum Apicomplexa, class Sporozoa, order Eucoccidiorida and the family Sarcocystidae (DUBEY et al, 2002). Herd infection levels may be maintained through transplacental infection by infected cows during gestation (exogenous transmission), or through reactivation of existing bradyzoites in the body of the infected cow (endogenous transmission). Mato Grosso has the largest cattle herd in the country, with ~28.5 million animals distributed on 102,162 ranches (ABREU et al, 2010; INDEA, 2014)

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Discussion

Conclusion