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Commonly used household surfaces in the Utah home of two infected and symptomatic monkeypox patients were covered with PCR-detected virus, yet no samples were culturable, according to a CDC investigation.

Among 30 samples taken 20 days since the start of the patients' isolation, 70% turned up positive on real-time positive PCR tests specific for non-variola orthopoxvirus or West African monkeypox, reported researchers led by Jack Pfeiffer, PhD, of CDC's Epidemic Intelligence Service and of the Utah Department of Health and Human Services.

Positive swabs were identified from non-porous items including a toilet seat, light switch, sink handle, banister, and computer mouse; porous objects such as a couch, blankets, and a chaise lounge; as well as a desk chair, a "mixed porous" object. The patients' TV remote, bathroom door handle, and thermostat returned inconclusive results.

But all culture results in the lab were negative.

"The inability to detect viable virus suggests that virus viability might have decayed over time or through chemical or environmental inactivation," wrote Pfeiffer and colleagues in . "Although both patients were symptomatic and isolated in their home for more than 3 weeks, their cleaning and disinfection practices during this period might have limited the level of contamination within the household."

But the group cautioned that these data are limited and called for more studies to "assess the presence and degree of surface contamination and investigate the potential for indirect transmission of monkeypox virus in household environments."

While Pfeiffer's team explained that monkeypox virus primarily spreads through skin-to-skin contact with the rash, scabs, lesions, body fluids, or respiratory secretions of a person with monkeypox, they also warned that "transmission via contaminated objects or surfaces (i.e., fomites) is also possible."

Visiting the home of someone infected with monkeypox should only be done with "appropriate precautions," Pfeiffer's group noted. Individuals in such a setting should wear a well-fitting mask and wash their hands, according to the authors, and also avoid touching surfaces and sharing utensils, clothing, bedding, or towels. The home should be disinfected according to recommendations.

Both patients in the study had mild disease, and had fatigue and body aches at the onset of symptoms. One patient reported lesions on the penis, lips, hands, legs, chest, and scalp as of day 10, and had resolution of symptoms by day 30.

The second patient had a lesion on the foot that spread to the leg and finger at day 11, but resolved by day 22. Overall, the number of lesions on the two patients was "small," according to the CDC report, and varied from "pimple-like" or ulcerated lesions, to those that were "characteristically well-circumscribed and centrally umbilicated."

During the PCR testing on day 20 -- wherein investigators wore personal protective equipment -- the housemates still had monkeypox and were still symptomatic. Investigators also collected information on the patients' household cleaning regimen and where they had cleaned ("mopping and daily use of a multisurface spray on most high-contact surfaces"). The researchers also learned that temperatures in the home were kept in a range between 69-75°F during isolation.

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