Prevalence of serological markers against measles, rubella, varicella, hepatitis B, hepatitis C, and human immunodeficiency virus among medical residents in Mexico.

BACKGROUND: Vaccination programs among health care workers are based on seroprevalence studies, which seldom include medical residents or students. The objective of this study was to determine the seroprevalence of antibodies against measles, rubella, varicella, hepatitis B (HBV), hepatitis C (HCV), and human immunodeficiency virus (HIV) among medical residents. METHODS: This study was designed as a prospective survey. A self-reported questionnaire was used to obtain the information. Serum samples were tested for antibodies by commercial immunoenzymatic assays. Statistical analysis was descriptive; history of exposure was evaluated as a diagnostic test and sensitivity, specificity, and predictive values were calculated according to Bayes theorem. RESULTS: Eighty-nine residents were included, the median age was 27 years, and 58 (65.2%) were female. Seventy-two (79.7%) had been vaccinated against HBV, but vaccination was complete in only 30/72 (41.6%). All were positive for measles and varicella, with the exception of one case for each. The serology for rubella was negative in 12 residents (10 women). Three residents had anti-core against HBV, with negative surface antigen. One positive case for HCV was confirmed by Western blot. All were negative for HIV. A history of prior varicella had a 100% positive predictive value; in contrast, the negative predictive value was quite low (7%). CONCLUSIONS: Negative serology for rubella among women and incomplete vaccination against HBV support the implementation of vaccination programs in medical schools in Mexico.

[Determining factors of rubella in the 10 to 14 year-old population in Mexico]. / Factores determinantes de la rubéola en población de 10 a 14 años de edad en México.

The clinical and epidemiological importance of rubella relates to its teratogenic effects. When this disease occurs in children, adolescents and adults, it is usually benign. On the other hand, these age groups are source of disease transmission to pregnant women. The serology studies on rubella carried in Mexico prior to 1974, detected seropositivity levels from 87.1 to 97.7 percent in children younger than 14 years of age. In contrast, the National Seroepidemiology Survey (NSS) (1988) reported a much lower seropositivity (69.3%) in children of the same age group, and a rate of 80 percent in women of reproductive age. This situation is a particular problem for Mexico where a high proportion of the pregnancies occur during adolescence. While previous research has commented on descriptive measures of seroprevalences in women, this study, which is based on a logistic regression model, has the purpose of identifying the factors associated with the immunological status of girls between 10 and 14 years of age. The variable which showed the most evident relation to the antibody levels for rubella was years of schooling. The odds ratios (OR) for seropositivity among those who finished secondary schooling was 2.05 times (CI 1.28-2.56) that of the illiterate group. Other statistically significant variables were related to residence, urban vs rural (OR = 1.69; CI 1.48-2.12) and age, 10 vs 14 years (OR = 1.93; CL 1.69-2.42). Based on the multivariate model, it was observed that the girls with a greater risk of seropositivity were those who live in urban areas, attend secondary school, and are 14 years of age, with an OR = 4.05 (G = 6,756.4 and 5,580 gl; p less than .001). The study concludes with the following considerations: the immunological levels of girls from 10 to 14 years of age are low, and the results of the NSS suggest that Mexican public health authorities should evaluate the policy of vaccination against rubeola in the population potentially at risk, and that the factors associated with the disease, in descending order, are: years of schooling, age, and place of residence. It is also necessary to carry out analytic studies which will identify the risks and the etiology of congenital malformations which are likely to have been associated with the occurrence of rubeola virus during pregnancy.

Lack of in vitro interference between SA-11 rotavirus and attenuated poliovirus type 1.

To determine if rotavirus interferes with the multiplication of poliovirus, and hence the efficiency of the polio vaccine, the effect of timing and concentration of Simian rotavirus (SSA-11) on polio-1 infection in MA-104 cells was studied in vitro by evaluating the cytopathic effect, the reduction of the infectivity titers and the visualization of viral particles by electron microscopy. We found that poliovirus 1 was able to replicate when the challenge dose was administered within the first 8 h following SA-11 infection and with titers ten times lower than those of rotavirus. Hence, non-interference effect was observed in this in vitro model.