In 2002, only 6 countries had circulating indigenous wild-type poliovirus, but from 2002 through 2007, wild-type poliovirus spread to 27 previously disease-free countries in Africa and Asia through the movement of infected travelers. Northern Nigeria was the source of most of these illnesses, which reached all the way to Indonesia. Vaccination campaigns, guided by laboratory-based surveillance, largely disrupted transmission in these places, but travel continues to result in the spread of polio. In 2010, even as polio incidence decreased in Nigeria and India, 2 large outbreaks demonstrated the risk of introduction from poliovirus reservoirs. Spread of poliovirus into Tajikistan from India caused an outbreak of 458 cases and, subsequently, 18 cases in 2 other Central Asian republics and Russia. In central Africa, a large outbreak resulted after introduction of the virus from Angola, producing 441 cases in the Republic of Congo and an additional 104 cases in neighboring Democratic Republic of Congo. In 2011, cases of wild-type polio were identified in 16 countries, although only 1 recognized case occurred in India, which subsequently had no reported cases in more than a year. Although polio does not pose a threat to most travelers, it remains a serious concern for migrants, pilgrims, and people displaced by conflict; outbreaks heavily tax the public health resources of affected countries.
DISEASE ASSOCIATED WITH GLOBAL GATHERINGS
The pilgrimage to Mecca is the world’s largest annual event, drawing approximately 2 million Muslims from across the globe to Saudi Arabia. The history of the Hajj pilgrimage is an example of how diseases can spread to home countries of returning travelers after an international mass gathering. The intermingling and close contact offer ample opportunities for transmission of infectious diseases and rapid dissemination as pilgrims return home. In 2000, this occurred with Neisseria meningitidisserogroup W-135. Some vaccines used at that time did not cover this serogroup. After the event, 90 infections in returnees and their contacts were seen across Europe. In contrast, the number of infections in North America, where quadrivalent vaccine that covered W-135 was in use, was small. The outbreak strain of W-135 also quickly surfaced across areas of Africa, Asia, the Middle East, and the Indian Ocean, altering the epidemiologic patterns of meningococcal disease. As a result of this outbreak and similar cases in 2001, pilgrims to the Hajj are now required to be vaccinated with the quadrivalent vaccine.
-People in America are now more likely to be traveling and working abroad. Over the past 14 years the number of passport holders in America has doubled, now making it about 1/3 of America’s population holds passports.
–Many countries require a yellow fever vaccination of people who are 1 year or older, in order to enter the country, when coming from infected areas. Though the US does not require this, I personally have received a yellow fever vaccination.