Subclinical bovine vaccinia: An important risk factor in the epidemiology of this zoonosis in cattle

• Published in: Research in veterinary science Vol. 114; pp. 233 - 235
• Main Authors: Rehfeld, Izabelle Silva, Matos, Ana Carolina Diniz, Guedes, Maria Isabel Maldonado Coelho, Costa, Aristóteles Gomes, Fraiha, Ana Luiza Soares, Lobato, Zélia Inês Portela
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-10-2017; Elsevier Limited
• Subjects: Animal lactation; Animals; Antibodies; Asymptomatic Infections - epidemiology; Blood; Blood - virology; Bovidae; Bovine vaccinia; Brazil - epidemiology; Calves; Categories; Cattle; Cattle category; Cattle Diseases - epidemiology; Cattle Diseases - virology; Cow's milk; Crusts; Dairy cattle; Dairy farming; Dairy farms; Deoxyribonucleic acid; DNA; DNA, Viral - analysis; Epidemics; Epidemiology; Farms; Feces; Feces - virology; Female; Food contamination & poisoning; Health care; Immunoglobulins; Infections; Lesions; Male; Milk; Milk - virology; Neutralization; Neutralizing; Outbreaks; Polymerase chain reaction; Public health; Risk Factors; Rural areas; Subclinical disease; Teats; Vaccinia; Vaccinia - epidemiology; Vaccinia - veterinary; Vaccinia - virology; Vaccinia virus; Vaccinia virus - isolation & purification; Veterinary medicine; Viability; Viral infections; Viruses; Zoonoses; Zoonoses - epidemiology; Zoonoses - virology; Brazil; Vaccinia virus; Subclinical disease; Bovine vaccinia; Epidemiology; Cattle category
• ISSN: 0034-5288; 1532-2661
• DOI: 10.1016/j.rvsc.2017.03.022

Bovine vaccinia (BV) is a zoonosis caused by Vaccinia virus (VACV) that mainly affects lactating cows and dairy farm milkers. The epidemiological role(s) of other cattle categories such as dry cows, bulls, and heifers in BV remains unclear. This study was performed to investigate VACV in affected dairy cattle herds and perifocal farms during an outbreak in Brazil. Crusts from lesions of cows' teats were collected from all farms with BV outbreaks. Milk, feces, blood, and serum were collected from symptomatic and asymptomatic lactating cows. Blood and serum were also sampled from other cattle categories (calves, heifers, dry cows, and bulls). The samples were tested for VACV by PCR, and to confirm VACV viability, VACV-positive samples were inoculated in BSC-40 cells and stained using immunoperoxidase. Neutralizing antibodies were investigated using plaque reduction neutralization test. Viral DNA was detected in milk, blood, and feces samples of symptomatic and asymptomatic dairy cows and in blood samples from other cattle categories on farms with and without confirmed BV outbreak. In affected farms, viable virus was identified in feces and milk samples from lactating cows and in blood samples from asymptomatic dry cows. Viable VACV was also identified in feces from lactating cows and one bull's blood sample from perifocal farms. Neutralizing antibodies were detected in 81.6% of the herds affected by BV and in 53.8% of the herds on perifocal farms. The presented data indicate a potential source of viral dissemination, which contributes to the persistence and spread of VACV in the environment.
•Detection of viable VACV particles in milk, feces and blood from dairy cows presenting Bovine Vaccinia (BV) clinical signs.•Detection of VACV DNA in milk, feces and blood from assymptomatic cattle from different age and gender categories.•Neutralizing antibodies against VACV were detected in cattle from BV perifocal farms.•Milk and feces may contribute to the persistence and spread of VACV in the environment.