The human monkeypox virus is spreading in Europe and the US among people who have not traveled to endemic areas. On July 23, 2022, WHO Director-General Tedros Adhanom Ghebreyesus declared monkeypox a public health emergency of international concern.
Human-to-human transmission of monkeypox virus usually occurs through close contact with lesions, body fluids, and respiratory droplets from infected people or animals. The possibility of sexual transmission is being investigated, as the current outbreak appears to be concentrated in men who have sex with men and has been associated with unexpected anal and genital injuries.
It is unknown whether domestic dogs and cats could be a vector for monkeypox virus. Here we describe the first case of a dog with confirmed monkeypox virus infection that could have been acquired through human transmission.
Two men who have sex with men attended Pitié-Salpêtrière Hospital, Paris, France, on June 10, 2022. One man (referred to as patient 1 hereinafter) is Latino, 44 years old, and living with HIV with undetectable viral loads with antiretrovirals; the second man (patient 2) is white, 27 years old, and HIV negative. Men are non-exclusive partners who live in the same household.
The men had developed anal ulceration 6 days after having sexual relations with other partners. In patient 1, anal ulceration was followed by a vesiculopustular rash on the face, ears, and legs; in patient 2, in the legs and back. In both cases, the rash was associated with asthenia, headache, and fever 4 days later.
Monkeypox virus was analyzed by real-time PCR ( LightCycler 480 System; Roche Diagnostics, Meylan, France ). In patient 1, virus was detected in skin and oropharynx samples; while in patient 2 viruses were detected in anal and oropharyngeal samples.
Twelve days after the onset of symptoms, her 4-year-old male Italian greyhound with no previous medical history presented mucocutaneous lesions, including pustules on the abdomen and a fine anal ulceration. The dog tested positive for the monkeypox virus using a PCR protocol, which involved scraping the skin lesions and rubbing the anus and oral cavity.
Skin and mucosal lesions in two patients and their dog with confirmed monkeypox virus
Monkeypox virus DNA sequences from dog and patient 1 were compared using next-generation sequencing ( MinION; Oxford Nanopore Technologies, Oxford, United Kingdom ). Both samples contained viruses of the hMPXV-1 clade, lineage B.1, which has been spreading in non-endemic countries since April 2022 and, as of August 4, 2022, has infected more than 1,700 people in France, mostly concentrated in Paris, where the dog first developed symptoms. Furthermore, the virus that infected patient 1 and the virus that infected the dog showed 100% sequence homology in the 19.5 kilobase pairs sequenced.
The men reported that they slept together with their dog. They had been careful to prevent their dog from coming into contact with other pets or humans from the onset of his own symptoms (i.e., 13 days before the dog began exhibiting skin manifestations).
In endemic countries, only wild animals (rodents and primates) have been found to carry the monkeypox virus. However, in the US, transmission of monkeypox virus has been described in prairie dogs and in captive primates in Europe that came into contact with imported infected animals. Infection among domestic animals, such as dogs and cats, has never been reported.
To our knowledge, the kinetics of symptom onset in both patients and subsequently in their dog suggest human-to-dog transmission of monkeypox virus . Given the lesions on the dog’s skin and mucosa, as well as the positive PCR results for monkeypox virus from anal and oral swabs, we hypothesize an actual canine disease, not a simple carrier of the virus. through close contact with humans or airborne transmission (or both). Our findings should prompt debate about the need to isolate pets from monkeypox virus-positive people. We call for more research into secondary transmissions through pets.
The authors declare no competing interests. This work was supported by the French National Research Agency on HIV/AIDS, Hepatitis and Emerging Infectious Diseases. We thank the patients and all the clinical and technical staff of the infectious diseases and virology departments of the Pitié-Salpêtrière Hospital (especially Anne-Geneviève Marcelin and Vincent Calvez) and the Bichat-Claude Bernard Hospital, who provided care to the patients and performed the virological study.
