Man catches smallpox-like virus through sex with someone who had been vaccinated against the disease
U.S military are vaccinated against smallpox before they are deployed abroadCan pass on related form of the disease via close contact if injection site is left uncovered
Virus causes rash and fever and can be deadly to those with compromised immune systems
14:13 GMT, 1 March 2013
15:41 GMT, 1 March 2013
A man has become infected by a smallpox-like virus after coming into close contact with someone who had been recently vaccinated against the deadly disease.
The infected 24-year-old from San Diego then passed the virus on to another man through sexual activity – a phenomenon known as tertiary transmission.
Although smallpox has been eradicated across the world, members of the U.S military are vaccinated against it before being deployed, due to fears of bio-terrorism.
The vaccinia virus (pictured) causes cowpox, which produces skin lesions in people. The condition is related to smallpox
They are injected with the vaccinia virus, which is a related form of the disease.
But rather than being administered with a hypodermic needle, it is given using a two-pronged needle dipped into the vaccine solution.
Because it is a live virus, the injection site remains contagious for a few weeks and should remain covered.
The open wound can easily transfer
the vaccinia virus to other parts of the body or other people, so it is only safe to expose it once the scab that has formed over the injection site has fallen off.
However, there have been more than 100 cases of transmission between vaccinated and unvaccinated people over the past decade.
There have been reports of vaccination transmission through other forms of intimate contact, such as between mother and child and even at gyms.
The vaccinia virus cannot cause smallpox, but causes a rash and fever and can be deadly if passed on to someone with a compromised immune system.
Smallpox vaccines are administered using a two-pronged needle dipped the vaccine. The site must then be kept covered until the scab has fallen off
In the latest case, the 24-year-old man went
to hospital complaining of a rash, with sores on his lips and genital area. He had been in sexual contact with a man who had received the smallpox vaccination.
His condition cleared up without complications, according to a report from the Centers for Disease Control and Prevention.
However, a second man was hospitalised after contracting the virus from sexual contact with the 24-year-old. He too had sores caused by the vaccinia virus.
He was treated with immune globulin intravenous, which boosts the body's natural response in patients with compromised immune systems.
treatment, the patient was discharged and his condition also cleared up
with no further complications.
Dr Marc Siegel, from NYU Langone Medical Center in New York, said the virus the two men caught was a 'kissing cousin of smallpox'.
'It can be transmitted if you are not careful,' he added.
The new report highlights the potential for the virus to be transmitted
through sexual contact and reinforces the need to keep the vaccination
wound covered, the agency said.
The report was published in the March 1 issue of the CDC's Morbidity and Mortality Weekly Report.