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Poliomyelitis in Oman. I. The last outbreak?
S H Al-Dhahry1, R L Koul, S M Al-Busaidy
1Department of Microbiology & Immunology, College of Medicine, Sultan Qaboos University, PO Box 35, Al-Khodh, Muscat 123, Oman. sdhahry@squ.edu.om
Acta Tropica
|October 16, 2001
Summary
Despite multiple oral polio vaccine (OPV) doses, two Omani children contracted paralytic poliomyelitis. This highlights potential OPV immune response gaps and the need for continued surveillance of wild poliovirus.
Area of Science:
- Epidemiology
- Virology
- Public Health
Background:
- Oman experienced three paralytic poliomyelitis outbreaks since 1988.
- The 1993 outbreak involved two unvaccinated children despite previous vaccination campaigns.
Purpose of the Study:
- To investigate the 1993 paralytic poliomyelitis outbreak in Oman.
- To identify the poliovirus strain and assess the effectiveness of oral polio vaccine (OPV).
Main Methods:
- Isolation and genomic sequencing of wild poliovirus type 1 from patients and contacts.
- Serum neutralizing antibody tests to assess immune response to OPV.
- Analysis of vaccination history and epidemiological data.
Main Results:
- Wild poliovirus type 1 was isolated from both children and several close contacts.
- Antibody tests indicated a poor immune response to OPV in the affected children.
- Genomic sequencing suggested a new importation of poliovirus from southern/western Asia.
- Supplementary immunization campaigns were implemented nationwide.
Conclusions:
- Multiple OPV doses did not prevent infection in children with sub-optimal immune responses.
- Paralytic poliomyelitis occurred in children with poor antibody response to OPV.
- Outbreak control measures effectively localized the outbreak to a single village.