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C A de Quadros

Publications and source records attributed to C A de Quadros.

At least 19 recordsLinked to original sources
PubMed1997

Measles vaccination and Guillain-Barré syndrome.

BACKGROUND: Guillain-Barré syndrome (GBS) has been associated with several infectious agents, and the possibility that the disorder may be caused by vaccination has been raised. We compared the numbers of cases of GBS observed immediately after mass measles vaccination campaigns with the numbers that would be expected from baseline rates, to assess whether there is a causal relation between measles vaccination and GBS. METHODS: We analysed data on 2296 cases of GBS reported to the Poliomyelitis Eradication Surveillance System of the Pan American Health Organization as cases of suspected poliomyelitis. These cases occurred among 73 million immunised children aged 9 months to 15 years in Argentina, Brazil, Chile, and Colombia, between January, 1990, and December, 1994. These children were targeted for mass measles vaccination campaigns (each lasting 1 month) in 1992 and 1993. The frequency of GBS cases observed during the vaccination campaigns or the next 42 days (the latent period) was compared with that during the rest of the study period, with the assumption of a Poisson distribution. FINDINGS: The average annual incidence of GBS was 0.62 per 100000 children aged 1-14 years. The number of cases that would be expected within any 72-day period would therefore be 92. The average observed number of cases during latent periods after measles vaccination was 97. The probability that 97 or more cases would occur during a period with an expected number of 92 was 0.31. INTERPRETATION: The average annual rates of GBS by age-group for the 5 years analysed were consistent with previous data; thus we are confident that the surveillance system is sufficiently sensitive. There was no statistically significant association between measles vaccination and GBS. If there is any causal relation, the number of GBS cases due to measles vaccination was so small that data from the vaccination of more than 70 million children were not sufficient to detect a rise in the number of observed GBS cases beyond the expected number.

Adolescent↗
PubMed1997

Epidemiologic study of Guillain-Barré syndrome in children <15 years of age in Latin America.

In 1986, surveillance of acute flaccid paralysis (AFP) cases among children <15 years of age was implemented in Latin America as part of the initiative to eradicate poliomyelitis from the Western Hemisphere. Data on AFP, including Guillain-Barré syndrome (GBS), could be analyzed from a regional registry system and from specific GBS studies in seven countries. Between 1989 and 1991, 3112 cases of GBS were reported in Latin America, representing 52% of all nonpolio AFP cases. From the studies in seven countries, a total of 1527 GBS cases (49%) were studied, representing an overall annual incidence rate of 0.91/100,000 children <15 years old. Follow-up investigations showed a persistent muscular weakness at 60 days, 6 months, and 1 year after onset in 61%, 14%, and 10% of children, respectively. This study confirms that with the disappearance of polio, GBS arises as the most common cause of AFP.

Adolescent↗
PubMed1997

National immunization days: experience in Latin America.

Organization of national immunization days (NIDs) in all countries in Latin America in which polio was endemic has been one of the key elements that led to the interruption of the circulation of the wild poliovirus in 1991 from the Americas. National initiatives for control or elimination of measles using similar strategies have emerged from the successful organization of NIDs for polio eradication and lead the way to the eventual global eradication of this major killer of children. The major reasons for the success of polio eradication in the Americas were the commitment of national authorities, well-defined strategies, sustainable effort, and the participation of all sectors of society.

Humans↗
PubMed1997

Certification of the eradication of indigenous transmission of wild poliovirus in the Americas.

In May 1985, the Pan American Health Organization launched an initiative to interrupt indigenous transmission of the wild poliovirus from the Western Hemisphere by the year 1990. The strategy to achieve this goal was based on the maintenance of high levels of immunity in the population at risk and the establishment of a surveillance system to detect polio cases and respond promptly with control measures. On 23 August 1991, a 2-year-old boy with acute flaccid paralysis due to wild poliovirus was detected in Junin, Peru, the last isolation of such a virus in the entire Western Hemisphere. In 1990, an International Commission for the Certification of Eradication of Poliomyelitis Eradication (ICCPE) was established by the Pan American Health Organization to eventually determine if transmission was interrupted. After 3 years of follow-up and review of surveillance data, the ICCPE declared that wild poliovirus transmission had been interrupted in the Americas.

Americas↗
PubMed1997

Eradication of wild poliovirus from the Americas: acute flaccid paralysis surveillance, 1988-1995.

In May 1985, the Pan American Health Organization proposed the goal of interruption of wild poliovirus transmission in the Western Hemisphere. An important component of the polio eradication strategy was conducting surveillance for cases of acute flaccid paralysis. Reported cases were thoroughly investigated, including the collection of stool samples for testing for the presence of wild poliovirus. The last patient with poliomyelitis due to wild poliovirus in the Americas had onset of paralysis on 23 August 1991 in Peru. Since then, >9000 cases of acute flaccid paralysis have been reported and thoroughly investigated; none has been confirmed as paralytic poliomyelitis due to wild poliovirus. On 29 September 1994, the International Commission for the Certification of Poliomyelitis Eradication declared the Americas to be polio-free.

Americas↗
PubMed1997

Eradication of wild poliovirus from the Americas: wild poliovirus surveillance--laboratory issues.

The Pan American Regional Poliomyelitis Laboratory Network, developed to support the program to eradicate indigenous wild poliovirus transmission in the Americas, included 10 laboratories, distributed in eight countries in the Americas, organized according to the diagnostic procedures they regularly performed. All laboratories isolated and typed virus in stool specimens, several did intratypic differentiation by nucleic acid probe hybridization, and 2 sequenced wild poliovirus isolates for molecular epidemiologic studies. High performance of the network was maintained through comprehensive training of virologists, continuous monitoring of laboratory performance, and prompt investigation of problems. Recommended field and laboratory procedures were regularly reviewed and revised to optimize sensitivity, specificity, and diagnostic efficiency. Close integration of field and laboratory surveillance was achieved through frequent meetings between virologists and epidemiologists, effective communication of program priorities, and the distribution of weekly surveillance reports.

Americas↗
PubMed1996

Measles elimination in the Americas. Evolving strategies.

The strategy currently used to control measles in most countries has been to immunize each successive birth cohort through the routine health services delivery system. While measles vaccine coverage has increased markedly, significant measles outbreaks have continued to recur. During the past 5 years, experience in the Americas suggests that measles transmission has been interrupted in a number of countries (Cuba, Chile, and countries in the English-speaking Caribbean and successfully controlled in all remaining countries. Since 1991 these countries have implemented one-time "catch-up" vaccination campaigns (conducted during a short period, usually 1 week to 1 month, and targeting all children 9 months through 14 years of age, regardless of previous vaccination status or measles disease history). These campaigns have been followed by improvements in routine vaccination services and in surveillance systems, so that the progress of the measles elimination efforts can be sustained and monitored. Follow-up mass vaccination campaigns for children younger than 5 years are planned to take place every 3 to 5 years.

Americas↗
PubMed1995

Risk of vaccine-associated paralytic poliomyelitis in Latin America, 1989-91.

A major factor influencing the success of poliomyelitis eradication in the Americas was the reliance on mass immunization campaigns with oral poliovirus vaccine (OPV). As global poliomyelitis eradication activities accelerate and campaign vaccine delivery strategies are applied elsewhere, it is critical to determine whether the risk of vaccine-associated paralytic poliomyelitis (VAPP) is altered when routine delivery strategies are supplemented with mass immunization campaigns. We analysed all 6043 cases of acute flaccid paralysis (AFP) reported in Latin America over the period 1989-91 in order to estimate the risk of VAPP. The overall risk was estimated to be one case per 1.5-2.2 million doses of OPV administered, compared with one case per 1.4 million doses administered in England and Wales (1985-91) and with one case per 2.5 million net doses distributed in the USA (1980-89). These data suggest that to eradicate poliomyelitis globally, strategies that rely on mass immunization campaigns to supplement routine delivery services, as recommended by WHO, do not appear to alter significantly the risk of VAPP.

Adolescent↗
PubMed1994

The desired field-performance characteristics of new improved vaccines for the developing world.

Although the vaccination initiatives undertaken during the past decade are the cornerstones for protecting the world's children and helping to ensure their survival and development, the vaccines currently being employed may become obstacles for further disease reduction or eradication. Their characteristics complicate or increase the burden on health care infrastructures to maintain or expand vaccine delivery systems. This paper examines an experience with the vaccine technologies that currently are being used by immunization programs in developing countries, illustrating the field problems and obstacles associated with their use. It discusses the advantages and benefits that would accrue if new or improved, heat-stable, multi-antigen vaccines that require only one or two, preferably oral, doses were to become available.

Child Health Services↗
PubMed1994

Intradermal administration of measles vaccines.

The aim of the study reported here was to determine if bifurcated needles or multiple puncture cylinders would prove suitable for administration of measles vaccines. Children 9 to 11 months old in São Paulo, Brazil, were assigned to receive either Biken-Cam 70 (5,000 TCID50/0.5 ml) or Edmonston-Zagreb (7,000 TCID50/0.5 ml) measles vaccines intradermally with a bifurcated needle or a multiple puncture cylinder. These devices are usually used to administer smallpox or BCG vaccine. The volume of vaccine inoculated was approximately 0.003 ml. Measles IgG antibodies were measured by enzyme-linked immunosorbent assay (ELISA) at the time of vaccination and 8 weeks later. The study participants were examined 14 days after inoculation for possible adverse reactions. Overall, the children's average age was 9.5 +/- 0.66 months at vaccination. None of the 45 recipients of Biken-Cam vaccine responded serologically. The 49 Edmonston-Zagreb vaccine recipients immunized with the multiple puncture cylinder had a somewhat higher serologic response rate (35%) and mean concentration of measles antibodies (323 mIU/ml) than those 51 who received the same vaccine administered with the bifurcated needle (26% and 291 mIU/ml, respectively). The rates of reported symptoms after vaccination did not differ significantly among the groups. Overall, the low serologic response rates following intradermal immunization with for devices tested in this study indicate that this route of administration is not suitable for routine administration of standard-titer vaccines.

Antibodies, Viral↗
PubMed1994

Lessons from Cuba: mass campaign administration of trivalent oral poliovirus vaccine and seroprevalence of poliovirus neutralizing antibodies.

The immunogenicity of trivalent oral poliovirus vaccine (TOPV), which is less effective in tropical than in temperate areas, may potentially be improved in several ways, including increasing the number of doses. Little information is available on TOPV when more than 6 doses are given. The situation in Cuba provides a unique opportunity to relate the seroprevalence of neutralizing antibodies to the dose of TOPV because Cuba has not reported culture-confirmed poliomyelitis since 1973 and TOPV is only administered in twice yearly 1-week mass immunization campaigns. Sera from 2000 children nationwide were studied for neutralizing antibody among children who received 0, 2, 4, 6 and 8 doses of TOPV. These doses were administered in the period 1989-91, when TOPV (from the USSR) was being used with 500,000, 200,000, and 300,000 median tissue-culture-infecting doses (TCID50) for types 1, 2 and 3, respectively--the 5:2:3 formulation. Seroprevalence of neutralizing antibody after two TOPV doses was 91.5% for type 1, 90.8% for type 2, and 45.9% for type 3. Seroprevalence of type-3 neutralizing antibody after 6 doses remained low (73.4%), but increased to 83.5% after 8 doses (P < 0.05). Although 16.5% of the children remained unprotected for type-3 infection even after 8 doses, mass campaign immunization strategies were sufficient to eradicate the transmission of wild poliovirus in Cuba. Because the seroprevalence of type-1 neutralizing antibody was high (91.5%) after two campaign doses, additional studies using different formulations are needed to determine whether simultaneous improvement in the type-3 response to two campaign doses can be achieved.

Antibodies, Viral↗
PubMed1993

Direct detection of wild poliovirus circulation by stool surveys of healthy children and analysis of community wastewater.

Cartagena, Colombia, was one of the last cities in the Americas known to have endemic poliomyelitis. After 3 cases were identified in 1991, two approaches for detecting continued silent transmission of wild polioviruses within a high-risk community were used: stool surveys of healthy children and virologic analysis of community sewage. Wild type 1 polioviruses were isolated from 8% of the children studied and from 21% of sewage samples. The proportions of wild polioviruses, vaccine-related polioviruses, and nonpolio enteric viruses were similar for both approaches. Wild poliovirus sequences were also amplified directly from processed sewage samples by the polymerase chain reaction using primer pairs specific for the indigenous type 1 genotype. The last reported cases associated with wild polioviruses in the Americas occurred in Colombia (8 April 1991) and Peru (23 August 1991). Direct sampling for wild polioviruses in high-risk communities can provide further evidence that eradication of the indigenous wild polioviruses has been achieved in the Americas.

Child, Preschool↗
PubMed1992

The surveillance challenge: final stages of eradication of poliomyelitis in the Americas.

Current levels of surveillance have contributed to substantial reductions in morbidity and mortality due to poliomyelitis in the Americas. Despite the success of the poliomyelitis eradication initiative, it has become critical that surveillance be intensified so that the absence of wild poliovirus circulation can be verified with confidence in countries not reporting confirmed cases of poliomyelitis. Cases of acute flaccid paralysis continue to be classified as compatible with poliomyelitis, because investigations of such patients do not provide sufficient information to rule out wild poliovirus as the cause of paralysis. At this stage of the eradication initiative, the presence of compatible cases in some countries in Latin America indicates a failure of the surveillance system. The greatest challenge for the eradication initiative may be correcting the remaining deficiencies of the existing surveillance system that hinder efforts to verify that wild poliovirus is no longer being transmitted in the Americas.

Adolescent↗