Outbreak of Paralytic Poliomyelitis in Albania, 1996: High Attack Rate Among Adults and Apparent Interruption of Transmission Following Nationwide Mass Vaccination

Abstract

After >10 years without detection of any cases of wild virus-associated poliomyelitis, a large outbreak of poliomyelitis occurred in Albania in 1996. A total of 138 paralytic cases occurred, of which 16 (12%) were fatal. The outbreak was due to wild poliovirus type 1, isolated from 69 cases. An attack rate of 10 per 100,000 population was observed among adults aged 19-25 years who were born during a time of declining wild poliovirus circulation and had been vaccinated with two doses of monovalent oral poliovirus vaccines (OPVs) that may have been exposed to ambient temperatures for prolonged periods. Control of the epidemic was achieved by two rounds of mass vaccination with trivalent oral poliovirus vaccine targeted to persons aged 0-50 years. This outbreak underscores the ongoing threat of importation of wild poliovirus into European countries, the importance of delivering potent vaccine through an adequate cold chain, and the effectiveness of national OPV mass vaccination campaigns for outbreak control.

Seroprevalence of Antipolio Antibodies among Children <15 Years of Age in Border Provinces in China

“…Second, the study subjects were children Ͻ15 years of age, and the immunity of adults was unknown. Adults were potential sources of WPV infection for children in their families, and WPV outbreaks have been characterized by a large proportion of adult cases in recent years (15)(16)(17)(18)(19). Finally, in addition to population immunity, other factors, including hygiene conditions, population density, and population mobility, etc., may affect WPV transmission.…”

“…But older age groups appear to be at a greater risk of infection in the case of WPV importation (36)(37)(38). Examples of importations in Albania and Namibia demonstrated the immunity gap among the elderly population (15,19), and outbreaks reported in adults may be related to low levels of antibodies in these individuals (39).…”

Robustness against serum neutralization of a poliovirus type 1 from a lethal epidemic of poliomyelitis in the Republic of Congo in 2010

“…This does not exclude inefficient immune protection as the necessary and most likely cause of the outbreak (5,9,28). However, it is intriguing that the ROC outbreak was associated with a much higher CFR than similar outbreaks in regions where WPV circulation had been interrupted and a pronounced incidence in adult patients occurred due to vaccination gaps, such as in Albania in 1996 (29), Namibia in 2000 (5) or Tajikistan in 2010 (6).…”

Development of an individual-based model for polioviruses: implications of the selection of network type and outcome metrics

“…Most people infected with poliovirus do not show any symptoms, which necessitates modelling the transmission of infections [5], but about 1/200 susceptible people becomes paralysed from a wild poliovirus infection [6][7][8]. The costs of outbreaks include both health costs experienced by paralysed individuals plus the impacts on their families, and the financial costs associated with treating patients and responding to the outbreak with vaccine campaigns to reduce transmission [9][10][11]. Two vaccines provide protection from disease (paralytic poliomyelitis), but incomplete protection from infection : live oral poliovirus vaccine (OPV) and inactivated poliovirus vaccine (IPV).…”