RESUMEN
Highly sensitive case definitions were first introduced by national poliomyelitis eradication programmes to avoid missing true cases of the disease, though false-positive diagnostic errors could still occur owing to low specificity. Extensive data from all 1620 cases of acute, flaccid paralysis reported in Brazil during 1987-88 provided an opportunity to study the characteristics of confirmed poliomyelitis cases and epidemiologically to evaluate potential case definitions that maximized both sensitivity and specificity. Cases that had been confirmed by wild poliomyelitis virus isolation were compared with those that had been rejected (non-polio cases). To guarantee the consistency of clinical, epidemiological and laboratory investigations, only cases less than 10 years of age that had been investigated within 15 days of the onset and with complete laboratory specimens were included. No single practical case definition combining both high sensitivity and high specificity emerged from the study. However, the results showed that poliomyelitis endemic countries with limited resources should give priority to the investigation of cases in less than 5-year-olds, cases with prodromal fever, cases without involvement in all four limbs, cases without progression greater than 3 days after the onset, and cases occurring in areas where poliomyelitis had recently been confirmed. In countries without laboratory resources, cases of acute, flaccid paralysis with initial involvement in one or both lower limbs and residual neurological sequelae at 60 days should be confirmed. Countries that are close to eradication may selectively reject any cases lacking laboratory confirmation, despite adequate specimen collection, if they do not have initial involvement in one or both lower limbs and residual neurological sequelae at 60 days.
PIP: In Sao Paulo, Brazil, physicians followed 85 full term, healthy, breast fed infants born between March 1986-September 1988 monthly for 1 year to compare their immunologic response to immunization with trivalent oral poliovirus vaccine (TOPV). They either received doses 1 day after birth and at 2, 4, and 9 months (group A) or at 2, 4, and 6 months (group B). They analyzed blood samples from the mother at childbirth, from the umbilical cord, and from the infant at 2, 4, 6, 9, and 12 months to measure poliovirus neutralizing antibodies. All but 1 infant had passively transferred antibodies at birth. Group A had higher polio antibodies during the 1st few months, greater seropositivity, and a lower proportion of susceptible infants than group B. In fact, at the end of 12 months, only 3.7% of infants in group A were susceptible to all 3 poliovirus types compared to 25.9% in group B. Seroconversion rates were considerably higher in group A infants from the 3rd dose forward (96.3-100%) than for those in group B (74.1-100%). The response for polioviruses 1 and 2 were essentially the same in both groups at 12 months (96.3-100%). The immunological response to poliovirus type 3 in group A was superior to that of group B at the end of 1 year (96.3% vs. 74.1%), however. Yet group B infants received their 1st dose of the vaccine at 2 months with a higher level of poliovirus 3 type (500,000 TCID50/dose) than group A infants received at birth (300,000 TCID50/dose). Thus immunization of newborns with TOPV provided more protection against polio than a higher vaccine concentration administered to infants beginning at months. This finding is especially relevant since polio type 3 was responsible for the polio outbreak in 1986 in northern Brazil.
Asunto(s)
Poliomielitis/diagnóstico , Brasil/epidemiología , Niño , Preescolar , Errores Diagnósticos , Reacciones Falso Positivas , Humanos , Lactante , Poliomielitis/microbiología , Poliomielitis/prevención & control , Poliovirus/aislamiento & purificación , Sensibilidad y EspecificidadAsunto(s)
Poliomielitis/prevención & control , Vacuna Antipolio Oral , Control de Enfermedades Transmisibles , Política de Salud , Humanos , Incidencia , América del Norte/epidemiología , Poliomielitis/epidemiología , Vigilancia de la Población , América del Sur/epidemiología , Organización Mundial de la SaludRESUMEN
In the span of 5 years since the eradication initiative was launched and only 3 years since external funds were made available, PAHO has been able to develop and implement a comprehensive program strategy for polio eradication that includes the following components: achievement and maintenance of high immunization levels (which include the supplemental strategies of national immunization days and mop-up operations); effective surveillance to detect all new cases; and a rapid response to the occurrence of new cases. Despite yearly increases in the number of cases of acute flaccid paralysis reported to the surveillance system, a decline in reported confirmed cases of polio has occurred since 1986 to record low levels in 1989. Cases in 1989 were reported from only 0.7% of the counties in the Americas. The occurrence of 24 wild-type virus isolates in 1989 were limited to only three geographic areas: northwestern Mexico; the northern Andean Region; and northeastern Brazil. At this writing the clock is ticking with only 3 months left to achieve the goal of interrupting transmission by the end of 1990. If the current level of effort is sustained and special efforts are directed at the remaining foci of infection, the eradication of the transmission of wild-type poliovirus from the Americas can be achieved. Continued external financial support will be critical if the effort is to succeed. The prospect of poliomyelitis eradication in the Americas led the 41st World Health Assembly of WHO to adopt a resolution in May, 1988, to eradicate the indigenous transmission of wild-type poliovirus from the world by the year 2000.(ABSTRACT TRUNCATED AT 250 WORDS)