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For years, scientists believed that because of a strong species barrier, most viruses cannot be passed from animal to human. It seems that nature is proving us wrong again. For the last decade, we have seen an increase in zoonotic diseases, which are animal to human passed viruses. Many diseases, even epidemic diseases, started out as zoonotic diseases: measles, smallpox, influenza, HIV, Ebola, Bubonic plague, salmonella, Rocky Mountain spotted fever, and diphtheria came to us this way.
Greater variable strains and mutations could be occurring from encroachment; that is humans in wildlife areas or vice versa. Similarly, in recent times avian influenza and West Nile virus have spilled over into human populations probably due to interactions between the carrier host and domestic animals.
The Canine Flu Cannot Be Transmitted to Humans, But There Are Some Viruses That Can
That said, with the canine flu epidemic [2] wreaking havoc on dogs across the country, many are comforted in knowing that this particular contagious virus cannot be passed to humans. However, with this heightened concern, dog owners are paying particular attention to the fact that some horrific flu-like illness can be transferred from dog to owner.
For instance, scientists have recently discovered that the highly contagious norovirus can be transferred from human to animal and vice versa.
A study from the American Society for Microbiology [3] says there’s a chance dogs and humans can give each other the stomach bug. In the latest issue of the society’s publication, “Journal of Clinical Microbiology,” Dr. Sarah Caddy, a veterinarian and Ph.D. student at the University of Cambridge, and Imperial College, London, calls for more testing of possible cross-contamination between pet and pet owner.
As a vet, Caddy had come across several stories from dog owners that both they and their dogs had come down with the stomach flu, formally known as norovirus. Noting little in the way of research in the area, she decided to tackle the topic. She found some dogs in the study exhibited antibodies to norovirus.
The Centers for Disease Control [4] explains the common virus is very contagious. A person may contract norovirus from another person, infected food or water, or by touching contaminated surfaces. The painful viral strain causes the stomach, intestines or both to become inflamed and produces symptoms ranging from nausea to vomiting and diarrhea. Norovirus is especially dangerous to children and seniors. The virus strikes as many as 21 million Americans (or about 6 percent of the population) annually, and can lead to 71,000 hospitalizations and 800 deaths.
Source [5]
An additional study [6] out of Finland confirms the findings that Dr. Caddy has come across.
Researchers at the University of Helinski’s Department of Food Hygiene and Environmental Health took 92 fecal samples from dogs living in households where either the dog or family members had recently experienced vomiting or diarrhea – the most common symptoms of norovirus infection. They found human strains of norovirus (HuNov) in 4 of these samples.
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When asked whether this means that dogs might not only carry human noroviruses but actually be sickened by them as well, von Bonsdorff noted that this study cannot answer that question.
What Can You Do?
Because norovirus is using pet dogs as a vehicle to transmit the virus back to humans it important to understand how the virus is transmitted. Norovirus is most highly concentrated in feces, but can also be transmitted through saliva and vomit. Ensuring that family members who are contagious, specifically small children and the elderly, make a concerted effort to keep their hands clean and wash their hands after handling the family pet.
Protect Yourself and Others from Norovirus
- Practice proper hand hygiene
Wash your hands [7] carefully with soap and water, especially after using the toilet and changing diapers and always before eating or preparing food. If soap and water aren’t available, use an alcohol-based hand sanitizer. These alcohol-based products can help reduce the number of germs on your hands, but they are not a substitute for washing with soap and water. - Take care in the kitchen
Carefully rinse fruits and vegetables, and cook oysters and other shellfish thoroughly before eating. - Do not prepare food while infected
People with norovirus illness should not prepare food for others while they have symptoms and for at least 2 days after they recover from their illness. - Clean and disinfect contaminated surfaces
After throwing up or having diarrhea, immediately clean and disinfect contaminated surfaces using a bleach-based household cleaner as directed on the product label. If no such cleaning product is available, you can use a solution made with 5 tablespoons to 1.5 cups of household bleach per 1 gallon of water. - Wash laundry thoroughly
Immediately remove and wash clothing or linens that may be contaminated with vomit or stool. Handle soiled items carefully—try not to shake them —to avoid spreading virus. If available, wear rubber or disposable gloves while handling soiled clothing or linens and wash your hands after handling. Wash soiled items with detergent at the maximum available cycle length and then machine dry.
Read more on preventing the spread of norovirus [8]
Related Information:
CDC – Transmission of Influenza Viruses from Animals to People [9]