Travel warning issued after polio outbreak in Dominican Republic, Haiti
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* Barbara Sibbald

Canadians planning a trip to Haiti or the Dominican Republic should take a trip to their local health unit before they leave, because Health Canada has advised all travellers to ensure that their polio vaccinations are up to date ([www.hc-sc.gc.ca/hpb/lcdc/osh/polio\_drh_e.html](http://www.hc-sc.gc.ca/hpb/lcdc/osh/polio_drh_e.html)).

Seven confirmed cases of poliovirus type 1 were reported in the Dominican Republic and Haiti between July and December 2000. They caused considerable concern among infectious disease specialists because the Western Hemisphere had been free of cases of wild poliovirus since 1991. The problem is now considered under control following a mass immunization. In the Dominican Republic alone, 1.2 million children were vaccinated in just 2 weeks.

The culprit virus is a derivative of oral poliovirus vaccine that appears to have recovered the neurovirulence and transmissiblity characteristics of wild poliovirus type 1. The US Centers for Disease Control and Prevention reports that the differences in nucleotide sequences among the outbreak isolates suggest that the virus has been circulating for about 2 years and has accumulated genetic changes that restored the essential properties of wild poliovirus.

Dr. Susan Tamblyn, head of Canada's National Advisory Committee on Immunization, noted that those who contracted the disease were either unvaccinated or incompletely vaccinated. 

“The outbreak is a powerful reminder that even polio-free areas need to maintain high coverage with polio vaccine until eradication has been achieved,” said Dr. Ciro de Quadros, head of vaccines for the Pan American Health Organization.