Recent research conducted by the U.S. Centers for Disease Control and Prevention (CDC) has shed light on the detection of Highly Pathogenic Avian Influenza (HPAI) A(H5N1) virus in wild terrestrial mammals in the United States. The study, published in the CDC’s Emerging Infectious Diseases journal, adds to the growing evidence of natural infections with the HPAI virus in mammals and expands the list of species susceptible to H5N1.
The research demonstrates that several mammal species, including red foxes, striped skunks, raccoons, bobcats, Virginia opossums, coyotes, fishers, and gray foxes, have tested positive for the H5N1 virus. The presence of the virus in these mammals can be attributed to various intrinsic factors, such as opportunistic dietary preferences, sharing of environments with infected birds, and the presence of immunologically naive animals during the avian outbreak.
Of particular interest is the finding that many red foxes were observed in urban or periurban environments, which could be linked to increased public reporting due to human interest in these animals. Additionally, it is worth noting that raccoons, skunks, opossums, and coyotes, commonly encountered in urban areas, were less represented in the study.
The primary mode of transmission into mammals is believed to be the ingestion of birds infected with the HPAI virus. While evidence of mammal-to-mammal transmission was not apparent in this study, previous experiments have shown that horizontal transmission can occur in certain domesticated animals. It is important to note that there have been limited human cases of H5N1 reported globally since December 2021.
The detection of H5N1 infections in wild mammals calls for increased surveillance to better understand the distribution and evolution of these viruses in wildlife. Continual monitoring of the HPAI virus in wild mammals could contribute to the development of effective preventive measures and a deeper understanding of the ongoing outbreak.
1. Which mammals were found to be infected with the H5N1 virus in the United States?
Multiple mammal species were found to be infected with the H5N1 virus, including red foxes, striped skunks, raccoons, bobcats, Virginia opossums, coyotes, fishers, and gray foxes.
2. How do mammals become infected with the H5N1 virus?
Mammals are primarily infected with the H5N1 virus through the ingestion of birds infected with the virus.
3. Are there any documented cases of mammal-to-mammal transmission of the H5N1 virus?
While mammal-to-mammal transmission of the H5N1 virus was not apparent in this study, previous research has shown that horizontal transmission can occur in certain domesticated animals.
4. What does this research suggest about the spread of the HPAI virus in wildlife?
The research suggests that sporadic spillover events of the HPAI virus into individual animals sharing the landscape with infected wild birds are responsible for the infections observed in terrestrial mammals.
5. Why is increased surveillance of the HPAI virus in wild mammals important?
Increased surveillance can help us better understand the distribution and evolution of the HPAI virus in wildlife, aiding in the development of preventive measures and the management of the ongoing outbreak.