As the Chinese government openly begins to speculate about the possibility of human-to-human transmission of the H7N9 bird flu strain, an international team of experts, including some from the World Health Organization, have been deployed to investigate the disease in the country.

If true, the development would quickly raise concerns of the disease outbreak leading to a pandemic. Flu experts have long warned once a particularly deadly strain of the flu, as H7N9 appears to be – it has killed 17 of the 87 people it has infected – becomes transmissible between humans, it can quickly spread.

The World Health Organization has said some of those who have contracted the virus have had "no history of contact with poultry," and the state-run China Daily newspaper says a boy in Shanghai may have caught the disease from his brother.

"Further investigations are still under way to figure out whether the family cluster involved human-to-human transmission," Feng Zijian, of the Chinese Center for Disease Control and Prevention, told the newspaper.

Glenn Thomas, a spokesperson for WHO, tells U.S. News that "it's still too early to say" whether there have been human-to-human transmission, but that the team they've sent there will be investigating the possibility.

"There's no evidence yet of sustained human-to-human transmission, but the team will be looking into this," he says.

Even if the disease can be spread between humans, a pandemic is not a certainty, experts say. In order to spread quickly, the virus would need to mutate to a form that is spread through incidental or casual contact. Transmission between family members is often a first step, because they generally have prolonged contact over the course of several days.

According to Zijian, human-to-human transmission "is possible, but is highly sporadic." Zijian said "people don't need to panic, because such limited human-to-human transmission won't prompt a pandemic."

Health officials in the country are still working to track down the origin of the disease, which has been found in Beijing, the Henan province and Shanghai.

Joseph Kim, president of Inovio, a company currently working on a vaccine for H7N9, says the virus' low pathogenicity in poultry – many of them have not been killed by the disease – is making the search more difficult.

"That's scary in a way because it's harder to detect – it can spread faster in chickens and other bird flocks without authorities knowing it," he says.

Kim also notes though the virus is less deadly in humans than H5N1 – a deadly bird flu that has killed more than 60 percent of the people it has infected but has not become transmissible between humans – it is still an extremely dangerous strain.

"The Spanish flu which killed millions only had a couple percent mortality rate," he says. "If this virus mutates to be transmissible from human-to-human it will be a major issue. You have the perfect storm of pandemic flu virus in that it's highly pathogenic and could potentially be spread easily."