Babesia bovis infection in cattle in the southwestern Brazilian Amazon

Chemoprophylaxis for babesiosis and anaplasmosis in cattle: case report

Cattle tick fever (CTF) causes significant economic losses in the livestock sector. The pathogenic action of the hemoparasites is associated with anemia, weight loss, abortion and reduced productivity, which result with animal death. Programs to prevent CTF involve several procedures, including immunization, chemoprophylaxis and use of ectoparasiticides, together with the vector control in the environment. The objective of this study was to report an acute outbreak of CTF in a group of 157 Hereford cattle from a farm without presence of the vector, that were moved to a farm in the same state with a high tick infestation (Rhipicephalus microplus). On the day before the transportation, the animals received a chemoprophylaxis with imidocarb dipropionate (3 mg/kg, SC), which was repeated 21 days after the first application. After 42 days, some animals showed signs compatible with CTF, which was confirmed through clinical examination, necropsy, histopathological and hemoparasitological analyses. The morbidity rate was 37.6% and the mortality rate was 24.8%. Calves that were recently weaned were the group most affected with the tick fever, morbidity (100% and mortality (73%). Chemoprophylaxis in association with use of ectoparasiticides was not sufficient to control the outbreak of the disease.

Characterization of cattle tick fever in calves from the northwestern region of Minas Gerais, Brazil

The present study aimed to characterize the importance of the Anaplasma marginale, Babesia bovis and Babesia bigemina in the genesis of cattle tick fever (CTF) among dairy calves in the northwest of Minas Gerais, Brazil. Blood samples from 300 calves were collected, followed by DNA extraction and nested PCR using oligonucleotide primers to amplify fragments of the semi-nested for the msp5 gene (A. marginale), sbp-4 (B. bovis) and rap-1a (B. bigemina) Among the examined calves, the prevalence of A. marginale was 55.6% (n=167/300), B. bovis was 4.0% (n=12/300) and B. bigemina was 15.3% (n=46/300), by PCR techniques. Parasitic forms of A. marginale and B. bigemina were found in 36,3% and 2,6% of the blood smears while B. bovis was not detected. There was a statistical difference between the positivity of infected animals in the age groups 1 (10-70 days) and (>70-300 days) for A. marginale and B. bigemina. A total of 15 calves with the classic symptoms of disease were examined, and the samples obtained were confirmed as a simple infection by A. marginale through semi-nested PCR. These results confirm bovine anaplasmosis as the primary cause of CTF among the calves of dairy cattle within the studied area.

Prevalence of Anaplasma marginale, Babesia bovis, and Babesia bigemina in cattle in the Campos de Lages region, Santa Catarina state, Brazil, estimated by multiplex-PCR

This study aimed to determine the prevalence of three common hemoparasites (Anaplasma marginale, Babesia bovis and Babesia bigemina) in cattle from 16 counties in the Campos de Lages region, Santa Catarina state, Brazil, and the factors affecting disease occurrence. The study population consisted of 257 clinically healthy animals from 21 rural farms. Bovine blood samples were collected by jugular venipuncture. DNA was extracted from whole blood by the phenol/ chloroform method. Genomic DNA extracted from blood samples was subjected to Multiplex PCR for screening of B. bovis, B. bigemina, and A. marginale using specific primers. Prevalences of A. marginale, B. bigemina, and B. bovis were 27%, 16%, and 29%, respectively. Mixed infection was observed in 17.5% of samples. The most frequent was Babesia bovis and Babesia bigemina in 6.62% of samples. A. marginale infection rates were statistically correlated with age groups of cattle. The infections detected in the study population were considered to be subclinical, based on the presence pathogen DNA and absence of clinical symptoms. Seasonality of the pathogens resulted in various degrees of infection, related to the age of the animals and the season. The Campos de Lages region is characterized by enzootic instability for these pathogens because of its climatic and geographic features.

Transplacental transmission of bovine tick-borne pathogens: Frequency, co-infections and fatal neonatal anaplasmosis in a region of enzootic stability in the northeast of Brazil

Bovine tick-borne disease (TBD) constitutes a worldwide group of diseases that result in great losses for dairy and beef cattle. With regard to the epidemiological profile of the diseases, the importance of transplacental transmission is still not very well understood. The aim of this study was to determine the transplacental transmission of TBD agents (Anaplasma marginale, Babesia bovis and B. bigemina) in a herd of dairy cattle that had been naturally infected in an area of enzootic stability in northeastern Brazil. Blood for serology of the three agents was collected from cows within 120 days of gestation and serology, haemogram and nPCR assays were performed after birth. Blood was collected from the calves within 3h of birth, and haemogram and nPCR assays were performed in all animals. Pre-colostrum serology was achieved in 34 animals. The Student's t-test was used to compare the haemogram results between animals that were positive and negative for the haemoparasites. The cows were seropositive for all agents in at least one of the examinations. We detected 15 cases of vertical transmission of A. marginale, 4 of B. bovis and 2 of B. bigemina in the 60 cows. In infected animals, co-infection was detected for A. marginale and B. bovis in 1 of 60 calves, and a triple infection was detected in one other calf. Fatal neonatal anaplasmosis was observed in 1 of 15 calves, in which death occurred within 24h of birth. From the results, we concluded that transplacental transmission of TBD agents occurs, including in cases of co- and triple-infection. Such transplacental transmission can cause neonatal death, increasing the importance of this form of epidemiological transmission and suggesting its role as a cause of undiagnosed neonatal death.