Polio Cases Rise in Yemen Outbreak
May 12, 2005 - 5:43:38 PM
Six million doses of monovalent oral polio vaccine type 1 (mOPV1) have been shipped to Yemen, as part of emergency measures to stop the ongoing polio outbreak in the country. UNICEF today confirmed that the vaccine will arrive in Yemen early next week, for use in the nationwide immunization campaign to be conducted end-May, to immunize all of the country's children under the age of five years. Ten WHO experts are presently working with national authorities to finalize the plans for the campaign, and train vaccinators and supervisors.
mOPV1 works faster than the trivalent oral polio vaccine to create immunity against type 1 poliovirus, the strain causing Yemen's outbreak. Health officials expect this vaccine to more rapidly stop the outbreak. Confirmation of the mOPV1 availability came as Yemen reported a further 41 cases today, up from 22 in late April. Epidemiologists expect that the total number of cases will exceed 100, before the outbreak is stopped. Yemen had been polio-free since disease surveillance began in 1996.
Experience shows that sporadic polio outbreaks in previously polio-free countries, such as Yemen and Indonesia, can be stopped quickly, provided high-quality immunization campaigns are implemented rapidly. While these events strain the financial resources of the global eradication effort, they do not threaten its ultimate success.
The real challenge to global eradication remains stopping polio transmission in the last remaining reservoirs of transmission, from where poliovirus has been exported, such as northern Nigeria, northern India and Pakistan. Epidemiological evidence demonstrates that polio's grip is rapidly slipping in all three of those key endemic countries. India has reported only 14 cases to date this year, all of them polio type 1. mOPV1 is now in use in parts of India to wipe out the last pockets of type 1 transmission. Pakistan has recorded only six cases to date in 2005, while Nigeria has largely driven polio out of its southern states, immunizing a record number of children in the past round.
Despite this progress, as long as the epidemic in Africa is ongoing, polio-free countries will continue to be at-risk of importations. Concern is particularly high to protect the Horn of Africa, where weak health systems, low levels of routine immunization and hampered access to all populations due to civil conflict means children in this area are at particular risk of potential spread of polio. While Somalia has not reported a case since October 2002, preventive immunization campaigns were conducted in February and March, and are being evaluated for any potential areas of low coverage.
To ensure the necessary polio campaigns are implemented in endemic and high-risk countries, a global funding gap of US$50 million must urgently be filled by July. An additional US$200 million is needed for 2006 activities.
Global eradication efforts have reduced the number of polio cases from 350,000 annually in 1988 to 1,267 cases in 2004. Six countries remain polio-endemic (Nigeria, India, Pakistan, Niger, Afghanistan and Egypt), with a further six where polio transmission is re-established (Burkina Faso, Central African Republic, Chad, Côte d'Ivoire, Mali and Sudan).
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