This article is more than 5 years old. Information may no longer be current.
Dog, opossum cases suggest new reservoirs for vaccinia virus
Click Here to Manage Email Alerts
A recent report detailing asymptomatic vaccinia virus in Brazilian dogs and opossums suggested that these mammalian species could act as reservoirs for the infection.
The cases complement previous data suspecting the infection — which most often affects cows and can spread to humans — could be transferred between wild and peridomestic rodents, and raise questions regarding the possibility of other mammalian vectors.
“More than one mammalian species, either wild or domestic, might be acting as a reservoir of group 1 [vaccinia viruses (VACVs)] from Brazil, possibly acquiring and transmitting the virus without showing clinical signs,” the researchers wrote. “This assumption corroborates [previous findings] which showed a high seroprevalence in dogs without clinical signs, questioning their possible role as a reservoir and suggesting more studies to confirm these findings.”
The researchers collected samples from humans and domestic and wild animals associated with two dairy farms affected by an outbreak of bovine smallpox-like disease in October 2012. Along with samples from 31 cows and two humans, researchers collected blood from six dogs, six pigs, two horses, two rams, three opossum, one coati and two wild rodents. Wild animals were captured and sedated using the recommended traps and anesthetic dose, and all creatures were evaluated for vesicles, scabs, crusts or other characteristic clinical signs of VACV.
An epidemiologic survey revealed no factors that could connect the two outbreaks. While no animals showed symptoms of infection at the time of blood collection, PCR testing revealed three dogs and three opossums carried VACV. In addition, gene sequencing showed that these samples had similar characteristics to other group 1 VACVs found in Brazil.
Previous data showed that group 1 and 2 VACVs were responsible for equally severe lesions in cows and humans, but mice infected with group 1 VACVs did not show clinical signs and can act as reservoirs for the disease, the researchers wrote. The detection of group 1 VACVs in other mammals could clarify the chain of transmission leading to outbreaks such as those affecting the two dairy farms.
“These findings might support the absence of clinical signs and raise major questions about the potential for more than one mammalian species, either wild or domestic, to act as a reservoir,” they wrote. “More studies are needed to further elucidate this ecologic situation.” – by Dave Muoio
Disclosure: The researchers report no relevant financial disclosures.
Click Here to Manage Email Alerts