A new paper in the Journal of Clinical Virology by Maija Summa, Carl-Henrik von Bonsdorff, and Leena Maunula investigates the role of pet dogs as sources of norovirus. Abstract below:

Human noroviruses (HuNoVs) are one of the leading causes of diarrhoeal diseases worldwide in all age groups. Virus transmission can occur via the faecal-oral route from person to person or via contaminated food, water, or surfaces. The most common NoV strains circulating among humans belong to genogroup GII. Thus far, to our knowledge, no HuNoVs have been detected in pets.

We investigated whether pet dogs could serve as carriers for HuNoVs and thereby transmit the infection to humans.

Ninety-two faecal samples of indoor pet dogs were obtained. The main criteria for sample collection were that the dog or humans in the household had suffered from diarrhoea or vomiting. All samples were screened for HuNoV genogroups GI, GII, and GIV by real-time one-step RT-PCR.

We detected HuNoV in four faecal samples from pet dogs that had been in direct contact with symptomatic persons. Three of the positive samples contained genotype GII.4 variant 2006b or 2008 and one GII.12. All NoV-positive dogs lived in households with small children and two dogs showed mild symptoms.

Our results suggest that HuNoVs can survive in the canine gastrointestinal tract. Whether these viruses can replicate in dogs remains unresolved, but an association of pet dogs playing a role in transmission of NoVs that infect humans is obvious.