Pet dogs—A transmission route for human noroviruses?
Section snippets
Background
As summarized in a recent review,1 human noroviruses (HuNoVs), members of the Caliciviridae family, are one of the leading causes of diarrhoeal diseases worldwide in all age groups. Virus transmission occurs via the faecal-oral route from person to person or via contaminated food, water, or surfaces. In an infected person, typical symptoms, such as nausea, vomiting, and diarrhoea, can appear within 12 h of virus ingestion and last for 1–3 days. In more severe cases, the infection lasts for
Objectives
The purpose of our study was to determine whether pet dogs could serve as carriers for HuNoV and thereby transmit the infection to humans either directly or by contaminating food or water.
Faecal samples
Ninety-two stool samples from 47 breeds 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. Samples were also accepted if the dog owner was in close contact with humans with a confirmed NoV infection. All 92 samples were collected outdoors carefully avoiding any other environmental contaminants in late winter (February–April) 2009 (56 samples) and 2010 (36 samples) in southern Finland and
Results
Of the 92 canine faecal samples, 4 (4.3%) tested positive for GII HuNoVs (Table 1). The Cq values of these samples varied from 23 to 37 (mean 30.98). All of the positive samples were collected from dogs living in households with more than two symptomatic persons suffering from vomiting, fever, and diarrhoea lasting 1–3 days. The two symptomatic dogs with HuNoV in their faeces suffered from nausea and loss of appetite for one day; one of these dogs also vomited once. As Fig. 1 shows, HuNoVs were
Discussion
Our results show that HuNoV genome can remain intact in the canine gastrointestinal tract. Thus, pet dogs can serve as carriers for HuNoVs. In Finland, HuNoV variants GII.4-2006b and GII.4-2008 were not only present in canine samples, but also commonly circulated in the human community during the epidemic seasons of 2009 and 2010 (data not shown). Our results and the close genetic resemblance of some genogroup IV NoVs found in humans to those that have been detected in dogs with diarrhoea12
Funding
This study was funded by the Academy of Finland (grant no. 1122782), the Finnish Veterinary Foundation, and the Walter Ehrström Foundation.
Competing interests
None.
Ethics committee approval
Not required.
Acknowledgements
We thank K. Söderberg, T. Kantala, M. Mattila, R. Mustonen, T. Summa, and P. Summa for their valuable contributions during sample collection.
References (25)
- et al.
Noroviruses: a comprehensive review
J Clin Virol
(2009) - et al.
Zoonotic aspects of infection with noroviruses and sapoviruses
Vet Microbiol
(2010) - et al.
Animal noroviruses
Vet J
(2008) - et al.
Molecular detection of noroviruses in sheep and pigs in New Zealand farms
Vet Microbiol
(2009) - et al.
Broad range RT-PCR assays targeting human noroviruses also detect swine noroviruses
Food Microbiol
(2009) - et al.
Real-time RT-PCR for norovirus screening in shellfish
J Virol Methods
(2005) - et al.
Genogroup-specific PCR primers for detection of Norwalk-like viruses
J Virol Methods
(2002) - et al.
Development and application of a capsid VP1 (region D) based reverse transcription PCR assay for genotyping of genogroup I and II noroviruses
J Virol Methods
(2004) - et al.
Role of hospital surfaces in the transmission of emerging health care-associated pathogens: Norovirus, Clostridium difficile, and Acinetobacter species
Am J Infect Control
(2010) - et al.
Deaths from Norovirus among the Elderly, England and Wales
Emerg Infect Dis
(2008)