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Transmission of Monkeypox Virus Through Contaminated Objects

1 September 2022 by Gertrud U. Rey

by Gertrud U. Rey

Image by macrovector on Freepik

Recent news headlines are fueling public fears about possible transmission of monkeypox virus through contact with contaminated objects like bedding or clothing. However, data generated using environmental sampling methods indicate that the likelihood of this type of transmission is very low.

In a study involving a two-person household in Utah in which both residents were infected with monkeypox virus, the investigators entered the home to obtain samples while the patients were present. The investigators then identified and swabbed various objects that had been touched frequently; including furniture, toilet handles, light switches, and remote controls. They subsequently processed the swab samples and performed PCR and cell culture analyses to detect the presence of monkeypox virus DNA and infectious monkeypox virus. Out of 30 samples tested, 21 yielded positive results by PCR, confirming that these 21 objects were contaminated with monkeypox virus DNA. However, none of the PCR-positive samples yielded any detectable virus in cell culture, suggesting that there was no infectious virus on any of the tested surfaces in that household.  

A second study involved a one-person houshold in Texas whose resident had been hospitalized with monkeypox virus infection. On day 15 after the patient had left the home, the investigators entered the house and obtained 31 swab samples from various household objects similar to those tested in the Utah home. PCR analysis revealed that 27 of the tested objects were contaminated with monkeypox virus DNA. Cell culture analysis showed that 7 of these 27 samples also contained viable virus, with six of the virus-positive samples originating from porous surfaces like bedding and clothing, and only one originating from a non-porous surface – the top of a coffee table. When the authors determined the concentration of virus in each of these seven samples using a standard titration assay, they found that only one of the samples produced a quantifiable amount of virus – a swab from an article of clothing that had been in prolonged, direct contact with active monkeypox lesions. In contrast, the quantities of virus isolated from the other six samples were all below the detectable limit of the assay, suggesting that even if an object is contaminated with monkeypox virus, the amount of virus is probably lower than the minimal infectious dose needed to establish a successful infection in a person.

A popular historical anecdote involving transmission of pox virus through inanimate objects describes how the US Army attempted to reduce the Native American population by gifting them smallpox virus-contaminated blankets. However, there are no reports or evidence indicating that this strategy actually worked, suggesting that it was probably ineffective. In fact, some historians cast doubt on whether this incident even took place.   

It is possible for pox viruses to remain viable on surfaces for long periods of time, but the conditions have to be just right. Studies involving variola virus (which causes smallpox) have shown that viral particles can stay viable on contaminated surfaces for up to 13 years if they are maintained at low humidity, low temperature, and in the absence of UV radiation. The authors of the Utah home study note that the residents cleaned and disinfected their home routinely during their illness, a practice that likely resulted in reduced viability and/or inactivation of infectious virus on all of the tested objects. In contrast, no such cleaning activities were noted for the Texas home. In addition, all windows of the Texas home were covered with closed blinds, a condition that likely reduced exposure to UV radiation and probably contributed to the preservation of viral particles.

Although it is possible to become infected with monkeypox virus by touching contaminated surfaces, the potential for this type of transmission appears to be limited, and the risk of acquiring monkeypox from hotel sheets, towels, or plane seats is probably very low. Monkeypox virus is transmitted most effectively through direct (i.e., skin-to-skin) contact with lesion material or inhalation of respiratory droplets during prolonged face-to-face interaction with an infected person.

Filed Under: Basic virology, Gertrud Rey Tagged With: contaminated objects, direct contact, fomites, infectious virus, monkeypox, monkeypox virus, PCR, transmission, viable, viral culture, viral DNA

TWiV 658: Everyone needs a H.E.A.R.T.

31 August 2020 by Vincent Racaniello

Daniel Griffin provides a clinical report on COVID-19, then we discuss CDC softening testing guidelines, Moderna vaccine phase I results in older people, Abbott’s $5 rapid antigen test, and reinfection with a distinct SARS-CoV-2 isolate, followed by listener email.

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Filed Under: This Week in Virology Tagged With: antigen test, coronavirus, COVID-19, diagnostic test, lateral flow assay, mRNA, pandemic, PCR, SARS-CoV-2, vaccine, viral, virology, virus, viruses

Children transmit SARS-CoV-2

30 July 2020 by Vincent Racaniello

Among the mountains of false information being peddled during the current pandemic, one of the most offensive is being used to drive opening of schools in the fall: that children do not transmit SARS-CoV-2. The results of multiple studies have shown that this assertion is incorrect. I’ll review two of them here.

One study examined 59,073 contacts of 5,706 COVID-19 patients in South Korea during January 20–March 27, 2020. The 5,706 index patients were grouped by age and the numbers of cases associated with that individual were identified. COVID-19 was detected in 11.8% of household contacts, and the rates were higher for contacts of children than for adults. The highest transmission rate, 18.6%, was observed for household contacts of school-aged children (10-19 years), and the lowest, 5.3%, for household contacts of children 0–9 years. This study was conducted in the middle of school closure; transmission rates are expected to be higher when school resumes.

A second study examined the presence of SARS-CoV-2 nucleic acids in nasopharyngeal swabs at a pediatric tertiary medical center in Chicago. The cohort, which included individuals less than a year of age to 65, all tested positive for SARS-CoV-2. Viral nucleic acid was detected by RT-PCR and the cycle threshold (CT) values for each individual were calculated. The CT value is inversely related to the quantity of nucleic acid present: the higher the number, the fewer copies of nucleic acid present in the sample.

The results show that young children (less than 5 years old) have as much or more SARS-CoV-2 nucleic acids in their upper respiratory tracts compared with older children (5-17 years old) or adults (over 18). While infectious virus was not measured, these differences mean that young children could have 10 to 100 times more infectious virus in their upper respiratory tracts.

The findings of these two studies show that young children are likely to be important drivers of SARS-CoV-2 transmission. Given the behavioral habits of young children in schools and day care centers, they will serve to efficiently amplify the virus among themselves, teachers, and their parents.

Schools may be opened only if stringent precautions are taken, including wearing of face masks, physical distancing, and most importantly, frequent testing. As discussed by Dr. Michael Mina on TWiV 640, the availability of a rapid and daily $1 test would make it possible to identify infected students and keep them at home. Unfortunately, such tests will not be widely ready for school opening this fall. Write your elected officials to demand that such tests be made available as soon as possible. There is no valid reason why we cannot achieve this goal.

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Filed Under: Basic virology, Commentary Tagged With: COVID-19, cycle threshold, diagnostic testing, pandemic, PCR, SARS-CoV-2, school opening, transmission in children, viral, virology, virus, viruses

TWiV 640: Test often, fast turnaround, with Michael Mina

18 July 2020 by Vincent Racaniello

Michael Mina joins TWiV to reveal why frequent and rapid SARS-CoV-2 testing is more important than accuracy, how a daily $1 rapid test could control the pandemic, and why group testing works.

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Intro music is by Ronald Jenkees

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Filed Under: This Week in Virology Tagged With: COVID-19, Ct, diagnostic test, dipstick test, group testing, pandemic, PCR, rapid antigen test, SARS-CoV-2, viral, virology, virus, viruses

TWiV 638: Do, there is no try

12 July 2020 by Vincent Racaniello

Daniel Griffin provides a clinical update on COVID-19, then Viviana Simon joins to review serological assays developed at Mt. Sinai for SARS-CoV-2 infection, tracking the outbreak in NYC, and listener questions.

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Intro music is by Ronald Jenkees

Send your virology questions and comments to twiv@microbe.tv

Show notes at microbe.tv/twiv

Filed Under: This Week in Virology Tagged With: antibodies, COVID-19, pandemic, PCR, SARS-CoV-2, serological assay, viral, virology, virus, viruses

TWiV 635: Mask hysteria

5 July 2020 by Vincent Racaniello

Daniel Griffin provides a clinical update on COVID-19, then we review SARS-CoV-2 shedding in children, how to resume school safely, the need for widespread testing and wearing face masks, and much more, including listener email.

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Filed Under: This Week in Virology Tagged With: COVID-19, face mask, infectious virus, pandemic, PCR, SARS-CoV-2, transmission from children, vaccine, viral, virology, virus, viruses

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