Role of schools in the transmission of measles in rural Senegal: implications for measles control in developing countries.
Patterns of measles transmission at school and at home were studied in 1995 in a rural area of Senegal with a high level of vaccination coverage. Among 209 case children with a median age of 8 years, there were no deaths, although the case fatality ratio has previously been 6-7% in this area. Forty percent of the case children had been vaccinated against measles; the proportion of vaccinated children was higher among secondary cases (47%) than among index cases (33%) (prevalence ratio = 1.36, 95% confidence interval (CI) 1.04-1.76). Vaccinated index cases may have been less infectious than unvaccinated index cases, since they produced fewer clinical cases among exposed children (relative risk = 0.55, 95% CI 0.29-1.04). The secondary attack rate was lower in the schools than in the homes (relative risk = 0.31, 95% CI 0.20-0.49). The school outbreaks were protracted, with 4-5 generations of cases being seen in the two larger schools. Vaccine efficacy was found to be 57% (95% CI -23 to 85) in the schools and 74% (95% CI 62-82) in the residential compounds. Measles infection resulted in a mean of 3.8 days of absenteeism per case, though this did not appear to have an impact on the children's grades. Among the index cases, 56% of children were probably infected by neighbors in the community, and 7% were probably infected at health centers, 13% outside the community, and 24% in one of the three schools which had outbreaks during the epidemic. However, most of the school-related cases occurred at the beginning and therefore contributed to the general propagation of the epidemic. To prevent school outbreaks, it may be necessary to require vaccination prior to school entry and to revaccinate children in individual schools upon detection of cases of measles. Multidose measles vaccination schedules will be necessary to control measles in developing countries. (+info)
nvited commentary: vaccine failure or failure to vaccinate?
aning of vaccine-induced immunity: is it a problem in Africa?
Seroepidemiological evaluation of 1989-91 mass vaccination campaigns against measles, in Italy.
In 1989-91 anti-measles vaccination campaigns were conducted in several Italian regions to vaccinate all children aged between 13 months and 10-12 years without a history of measles or measles vaccination. This study was conducted to evaluate serological status after the mass vaccination campaigns. In 1994, capillary blood samples were collected from randomly selected children, aged 2-14 years, living in 13 local health units. Antibody titres were determined by ELISA. Blood spot samples were analysed for 4114 (75.6%) of 5440 selected children. Among the 835 that reported measles before 1990, 806 (96.5%) were immune and of the 2798 vaccinated, 2665 (95.2%) were immune. The Edmoston-Zagreb (E-Z) strain vaccine was associated with a lower level of immunity than the Schwarz (SW) strain. A history of measles identified almost all immune children. Vaccination with the SW strain conferred persistent immunity (at least 5 years) in 98% of vaccinees. The strategy was able to unite natural and induced immunity. (+info)
Characterization of a new genotype of measles virus detected in China and England.
We report the co-circulation of a new lineage of measles virus (MV) and an Edmonston-like (Ed-like) genotype of MV in China during 1995-7. Sequence analysis of 25 strains was performed on a 282 nucleotides (nt) region of the nucleoprotein (N) gene, a 450-nt region of the haemagglutinin (H) gene and a 152-nt region of the matrix (M) gene by direct sequencing of RT-PCR amplicons obtained from clinical specimens. The entire H gene was sequenced from two strains. The results showed that 24/25 Chinese strains belonged to a new genogroup and were distinct from the vaccine strains used in China and the UK, and also from MV strains previously described in Europe, Africa and the USA. The remaining strain was Ed-like. Two strains of the new genotype (IV) and one of the Ed-like genotype were also detected in the UK in 1996. (+info)
Measles eradication: experience in the Americas.
In 1994, the Ministers of Health from the Region of the Americas targeted measles for eradication from the Western Hemisphere by the year 2000. To achieve this goal, the Pan American Health Organization (PAHO) developed an enhanced measles eradication strategy. First, a one-time-only "catch-up" measles vaccination campaign is conducted among children aged 9 months to 14 years. Efforts are then made to vaccinate through routine health services ("keep-up") at least 95% of each newborn cohort at 12 months of age. Finally, to assure high population immunity among preschool-aged children, indiscriminate "follow-up" measles vaccination campaigns are conducted approximately every 4 years. These vaccination activities are accompanied by improvements in measles surveillance, including the laboratory testing of suspected measles cases. The implementation of the PAHO strategy has resulted in a marked reduction in measles incidence in all countries of the Americas. Indeed, in 1996 the all-time regional record low of 2109 measles cases was reported. There was a relative resurgence of measles in 1997 with over 20,000 cases, due to a large measles outbreak among infants, preschool-aged children and young adults in Sao Paulo, Brazil. Contributing factors for this outbreak included: low routine infant vaccination coverage, failure to conduct a "follow-up" campaign, presence of susceptible young adults, and the importation of measles virus, apparently from Europe. PAHO's strategy has been effective in interrupting measles virus circulation. This experience demonstrates that global measles eradication is an achievable goal using currently available measles vaccines. (+info)
Candidate viral diseases for elimination or eradication.
This article discusses the possibilities for elimination or eradication of four viral diseases--measles, hepatitis B, rubella and yellow fever. (+info)
Bacterial pneumonia as a suprainfection in young adults with measles.
The aim of this study was to report the clinical and laboratory characteristics of bacterial pneumonia related to measles infection, and also to assess any correlation between severity and time of onset. Four hundred and twenty-four previously healthy young males (age 22+/-2.1 yrs) were hospitalized with typical symptoms and signs of measles. One hundred and twelve (26%) developed bacterial pneumonia on admission (n=41), during their hospital stay (n=20) or days after their discharge (n=51): groups A, B and C, respectively. Single lobar consolidation was the most common finding, accounting for 89% of cases. Pleural effusion was uncommon and associated in half of the cases with empyema. A microbiological diagnosis was made in 81 cases. Streptococcus pneumoniae (65 cases) and Klebsiella pneumoniae (9 cases) were the most commonly identified organisms. Patients from group C had significantly higher values of white blood cell count and erythrocyte sedimentation rate, and lower values of arterial oxygen tension (14+/-0.8 x 10(9) x L(-1), 88+/-4 mm and 6.3+/-0.4 kPa (47+/-3 mmHg), respectively) than the other two groups. There were no deaths during the hospitalization period. The mean duration of hospital stay was 13+/-2.4 days and was longer in the presence of K. pneumoniae infection (19+/-1.6 days). Six patients from group C were admitted to the intensive care unit. In conclusion, these data suggest that bacterial pneumonia associated with measles is not unusual in hospitalized adults, and it seems to be more severe when it occurs days after the onset of rash. (+info)