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Polio outbreak in Algeria: epidemiological, virological and vaccinational aspects
Z Kadi1, A Bouguermouh, O Akacem
1Department of Virology, Pasteur Institute of Algiers, Sidi-Fredj.
Abstract:
During a poliomyelitis outbreak (October 1983) in El Oued territory (Algeria) 28 cases were diagnosed. All the patients were under 4 years old. The ratio of females to males was 0.33. No deaths occurred during this epidemic. 25 of the 28 polio cases were diagnosed by cell culture and 81% were polio type 1. The epidemiological survey established that the epidemic was due to the insufficiency of vaccination coverage, since the consumption of antipolio vaccine in the epidemic area had dropped by 25% from 1982 to 1983. 7 of the 28 polio cases had been given at least 3 injections of vaccine at the correct intervals. 5 of 8 vaccine samples from the epidemic area had an insufficient titre of polio type 1. These observations showed that the nature of the vaccine, whether killed or live virus, was less important for controlling poliomyelitis than providing medical and sanitary facilities to ensure good vaccination coverage.
Insights
A 1983 poliomyelitis outbreak in Algeria was linked to insufficient vaccination coverage and low vaccine potency. Ensuring adequate medical facilities and vaccine quality is crucial for controlling polio, not just vaccine type.
Area of Science:
- Epidemiology
- Public Health
- Virology
Background:
- Poliomyelitis outbreaks pose significant public health risks, particularly in areas with suboptimal vaccination rates.
- Understanding the factors contributing to polio outbreaks is essential for effective disease control strategies.
Purpose of the Study:
- To investigate the causes of a poliomyelitis outbreak in El Oued territory, Algeria, in 1983.
- To identify factors contributing to the outbreak, including vaccination coverage, vaccine efficacy, and virus type.
Main Methods:
- Epidemiological investigation of 28 diagnosed poliomyelitis cases.
- Cell culture for polio virus identification and typing.
- Analysis of vaccine consumption data and vaccine sample titres.
Main Results:
- The outbreak primarily affected children under 4 years old, with 81% of cases being polio type 1.
- Insufficient vaccination coverage, a 25% drop in vaccine consumption from 1982-1983, was identified as a key factor.
- Suboptimal titres were found in 5 out of 8 vaccine samples, indicating potential vaccine quality issues.
- Despite vaccination, 7 cases had received at least 3 vaccine doses, suggesting issues beyond just coverage.
Conclusions:
- Effective poliomyelitis control relies heavily on robust vaccination coverage and high-quality vaccines.
- Public health interventions should focus on ensuring access to medical and sanitary facilities to maintain adequate vaccination rates.
- The type of polio vaccine (killed or live virus) was less critical than ensuring proper administration and vaccine potency.