Persistence of vaccine-derived poliovirus following a mass vaccination campaign in Cuba: implications for stopping polio vaccination after global eradication.

BACKGROUND: With substantial progress made toward polio eradication, developing the appropriate strategy for discontinuing global oral poliovirus vaccine (OPV) after global eradication becomes increasingly important. At issue is the theoretical risk of independent circulation of potentially virulent OPV-derived strains. Because Cuba uses OPV only in mass campaigns, it represents an ideal site to assess vaccine-derived poliovirus persistence. METHODS: Infants born after the 1997 biannual mass campaigns were evaluated for past (neutralizing antibody) or current (virus excretion) evidence of vaccine-derived poliovirus exposure. We obtained sera and/or stool specimens from 861 infants; a second serum from 218 infants. RESULTS: All stool specimens were poliovirus negative. Of 762 infants, 113 (14.8%) had initially detectable poliovirus type 1 antibody, 193 (25.3%) type 2, and 94 (12.3%) type 3. A precipitous antibody decline occurred in initially positive sera. CONCLUSIONS: Our results suggest that in a country with high population immunity, vaccine-derived virus is unlikely to establish ongoing circulation.

Treatment of respiratory syncytial virus infection with vitamin A: a randomized, placebo-controlled trial in Santiago, Chile.

BACKGROUND: Treatment with high dose vitamin A reduces complications and duration of hospitalization for children with measles. In respiratory syncytial virus (RSV) infection, as with measles, low serum vitamin A concentrations correlate with increased severity of illness. METHODS: To determine whether high dose vitamin A treatment is also effective for treating RSV disease, we conducted a randomized, double blind, placebo-controlled trial among 180 RSV-infected children between 1 month and 6 years of age at three hospitals in Santiago, Chile. Children with nasal washes positive for RSV antigen were given oral vitamin A (50,000 to 200,000 IU of retinyl palmitate, doses according to age; n = 89) or placebo (n = 91) within 2 days of admission. RESULTS: There was no significant benefit from vitamin A treatment for the overall group in duration of hospitalization, need for supplemental oxygen or time to resolve hypoxemia. For the subgroup of children with significant hypoxemia on admission (room air oxygen saturation level < or = 90%), those given vitamin A had more rapid resolution of tachypnea (P = 0.01) and a shorter duration of hospitalization (5.5 vs. 9.3 days, P = 0.09). No toxicities were seen, including excess vomiting or bulging fontanel. CONCLUSIONS: If vitamin A has a beneficial effect on the course of RSV disease, it may be seen only in more severely ill children.

Risk factors for genital papillomavirus infection in populations at high and low risk for cervical cancer.

This study sought to determine risk factors for genital infection with papillomavirus (HPV) in Panamanian women 20-49 years old. Subjects were randomly selected from Herrera and Panama provinces (cervical cancer incidence 79 and 25/100,000, respectively). Participants were interviewed to determine sexual behavior. Cervicovaginal lavage specimens were obtained to test for HPV DNA by commercial dot blot hybridization. HPV-16/18 DNA was detected significantly more frequently (5%) in Panama than Herrera (2%) samples (P = .002). Clearly, infection with high-risk HPV types alone cannot account for the differences in cervical cancer incidence between the two populations. HPV-16/18 detection decreased with increasing years of sexual experience among all women in Panama and among women with multiple partners in Herrera. However, HPV-16/18 detection did not change with sexual experience among monogamous women in Herrera. Thus, the epidemiology of HPV is complex and reflects both virus- and population-specific factors.

Barriers to medical care of Mexican-Americans: the role of social class, acculturation, and social isolation.

Literature on medical care utilization by Mexican-Americans suggests that patterns of utilization can be explained, in part, by acculturation, social class and social isolation. The relative importance of these variables is explored in a survey of a rural Mexican-American community in Southern Texas. Data on 152 families are analyzed using a logit analysis, with utilization as the outcome variable. The results suggest that acculturation has a direct effect, while social class and social isolation interact to have a weak effect independent of acculturation. These results confirm the importance of understanding all three variables in planning and implementing medical care programs in Mexican-American communities.