Use of a generalized additive model for a spatial analysis of bovine brucellosis risk in the state of Mato Grosso in 2002 and 2014.

Diseases that affect cattle represent obstacles to the development of livestock activity. Brucellosis is a significant such disease because it is transmissible, has a chronic nature, and causes health and economic damages to the herd and rural producer. Data from surveys performed in 2002 and 2014 were compared to identify the spatial distribution of bovine brucellosis and to evaluate clusters of outbreaks and areas of greater risk to have infected cattle in the state of Mato Grosso, Brazil. The present study analyzed the data obtained in the aforementioned investigations with a statistical model based on a spatial point process called a generalized additive model (GAM). The analysis made it possible to identify the regions of highest and lowest risk in the state of Mato Grosso. Of the 1001 properties analyzed in 2002, 198 were in areas with high-odds ratio, and 121 were in a low-odds ratio area. Of the 1248 properties sampled in 2014, 119 were in a high-odds ratio area, and 162 were in a low-odds ratio area. Areas with high-odds ratio are more likely to have infected cattle and can be considered to be at higher risk for the disease. The results of the present study highlight the reduction in foci, prevalence, and its relationship with the spatial distribution of bovine brucellosis. The study results should help the official defense service of Mato Grosso direct its activities according to the profile of each region.

Seroprevalence, spatial analysis and risk factors of infection with Neospora caninum in cattle in Brazils northern Pantanal wetland

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.

Resumo Neosporose é causada por um protozoário intracelular obrigatório, Neospora caninum. É considerada uma das causas mais comuns e frequentes de aborto em bovinos em todo o mundo. Para avaliar a prevalência de anticorpos anti- N. caninum e fatores de risco associados, amostras de soro foram coletadas de 2.452 bovinos em 262 fazendas no Pantanal norte, estado de Mato Grosso, Brasil. Cada fazendeiro preencheu um questionário para posterior análise dos dados epidemiológicos. Anticorpos anti-N. caninum foram detectados por meio da reação de imunofluorescência indireta (RIFI), utilizando um ponto de corte de 1:100. A prevalência total de anticorpos anti-N. caninum foi de 25,44% (Intervalo de Confiança - IC 95%; 20,10%; 30,78%) e a prevalência por rebanho foi de 76,72% (IC 95%; 71,60%; 81,84%). A presença de cães, a ocorrência de abortamento em vacas e a venda de bovinos para reprodução estiveram estatisticamente associadas à soropositividade em rebanhos, enquanto, o risco de fêmeas serem soropositivas para N. caninum foi maior em animais com idade 6 anos e na presença de cães. A análise espacial indicou que o risco relativo da doença é espacialmente constante e que as fazendas com maior prevalência de anticorpos anti-N. caninum estão localizados ao sul da região em estudo.