(CBS) Health officials are warning about the spread of polio in Pakistan and China.
The World Health Organization said there have been 84 cases in Pakistan as of September 13, up from 48 cases during the same period in 2010. And the same strain of polio in Pakistan has now spread to China.
The outbreak in China - the first since 1999 - has claimed one life and sent another nine people to the hospital, CNN reported.
What's causing the outbreaks? The organization says Pakistan's immunization efforts have been inadequate, especially in "security-compromised" regions. And health officials worry that the virus that causes polio will spread further in November, as Muslims travel to Mecca in Saudi Arabia for the Haj pilgrimage.
Helen Yu, an official with the WHO's Beijing office, warned that the virus could spread beyond the affected areas.
"Although other areas in China or other countries are not immediately at risk due to the geographic distance to the affected province, the polio virus can travel great distances and find susceptible populations, no matter where they live," she told CNN.
Polio is a crippling and potentially fatal infectious illness. It spreads through food and water and from one person to another via the fecal-oral route - meaning contact with the stool of an infected person. There is no cure, but there are effective vaccines.
There is little risk of contracting polio in the U.S., but the CDC says the disease remains a risk to travelers to certain countries. Anyone heading to one of these countries should first check with a doctor to review his/her polio vaccination status.
The World Health Organization has more on polio.