Outbreak of Poliomyelitis in Albania and Neighboring Countries in 1996

During the 1996 outbreak of poliomyelitis in Albania and neighboring countries, comprehensive laboratory investigations of 145 Albanians afflicted by acute flaccid paralysis (AFP) were carried out. A total of 125 stool specimens or rectal swabs and 120 samples of venous blood were screened for poliovirus types 1, 2, and 3 and the homotypic neutralizing antibody (3). Only 74 cases were labelled as wild type 1 poliovirus-induced AFP, though the number would be 85 or more if samples exclusively positive for antipoliovirus immunoglobulin M (IgM) were also included. There is no information about the possible role of enteroviruses other than poliovirus in the etiology of AFP among the remaining Albanians afflicted by AFP during the 1996 outbreaks. The roles of coxsackievirus types A4, -6, -7, -9, -11, -14, and -21 and B1 to -6; echovirus types 1, 2, 3, 4, 6, 7, 9, 11, 14, and 16; and enterovirus types 70, 71, and 72, documented to cause AFP (5), could not be minimized in the Albanian population. Furthermore, enterovirus 71 was implicated during the 1990s for causing acute neurological disease with AFP in 24 patients in Brazil (1).

The 1996 Albanian outbreak was curtailed by two mass vaccination campaigns targeted to persons aged 0 to 50 years (3). The exclusion of those aged 50 years and above from the immunization programs is unfortunate. A 65-year-old British male was afflicted with type 1 poliovirus while on vacation in Morocco. The poliovirus exposure induced a symmetrical weakness in his lower limbs (2). Yet another tourist, a 62-year-old healthy man, acquired poliomyelitis during a vacation in a beach resort in Morocco (4). Such reports are a grim reminder of the presence of a fair number of poliovirus-antibody-negative individuals among those aged 50 years and above in industrialized countries as well as in other countries where well-organized national immunization programs have reduced the incidence of poliovirus-induced AFP to negligible levels. Persons currently over 50 years of age would not have been offered any polio vaccine during childhood: inactivated or live poliovirus vaccines were not available in those days.

Prospective surveillance for poliovirus-induced AFP should include all those aged 50 years and above, as they might continue to constitute “virgin soil” for propagation of wild polioviruses. Constant serosurveillance for poliovirus antibodies and immunizations of all those in their 50s or older would be essential to tackle future poliomyelitis outbreaks in industrialized or developing countries with little incidence of poliomyelitis.