Primary Dengue Infection in Patients Requiring Hospitalization During an Outbreak in a Low Incidence Mexican Region.

Background: Dengue manifestations can range from subclinical to fatal. The study of factors that influence dengue's clinical severity can provide information to potentially limit or predict severe cases. Secondary infection (SI) with a different dengue serotype has been recognized as an important determinant of severity. However, severe dengue (SD) manifestations, including shock, can happen during primary infection (PI) too and the mechanisms involved are less understood. To characterize the severe manifestations associated to PI, we distinguished between primary and secondary dengue cases in hospitalized patients from a region of low and recent dengue incidence in central Mexico. This region can serve as a model for dengue's behavior as it spreads to new areas worldwide. Methods: Dengue-specific immunoglobulin M (IgM) and IgG concentrations were measured in the serum of 78 hospitalized patients with dengue hemorrhagic fever, and their ratios were used to discriminate between PI and SI, as recommended by World Health Organization. Clinical and laboratory manifestations were compared between PI and SI. Results and Conclusions: PI was detected in 23% of hospitalized dengue cases, a proportion similar to that reported in high-incidence regions in Mexico. PI was more frequent in 16- to 40-year-olds, and was absent in patients older than 60 years. Only dengue with warning signs and SD were present in the studied population of hospitalized patients, and case frequency decreased with clinical severity both in PI and SI groups. No significant differences in demographics, laboratory tests, or symptoms were found between PI and SI, which illustrates that cases requiring hospitalization during outbreaks can be severe, even if they are PI. This information can help plan for sanitary contingencies in places where dengue is recently emergent and numerous PI cases are expected. The mechanisms involved in PI clinical severity need to be studied further.

Hepatitis B surface antibodies in medical students from a public university in Puebla, Mexico.

Although preventable with vaccination, Hepatitis B virus (HBV) infection is a major health concern, with ∼400 million people at risk of developing the chronic form of the disease worldwide. The anti-HBV vaccine consists of a recombinant HBV surface antigen (HBsAg), which induces specific anti-HBs antibodies and confers 95% protection for >20 y. The aim of the present study was to analyze the response to HBV vaccination by measuring anti-HBs antibodies in serum samples from medical students of a public university in Puebla, Mexico. HBV infection markers HBsAg and anti-HBs, were also determined. A total of 201 students were included and vaccination coverage was found at 54%. Overall seropositivity for HBsAg, anti-HBc and anti-HBs determined by ELISA was 0.5%, 1.0% and 47%, respectively. Protective levels of anti-HBs >10 mIU/mL were found in 93.2% of subjects vaccinated with 2 or 3 doses and in 40% of those vaccinated with a single dose; while only 4.8% of unvaccinated subjects were anti-HBs positive. The response to the HBV vaccine was different in each participant, despite similar vaccination scheme. A history of blood transfusion/organ transplant or more than 2 sexual partners was significantly associated with anti-HBc positivity, OR = 399 (p = 0.010) and OR = 19.9 (p = 0.044), respectively. HBV immunization coverage was low in our sample compared with reports from countries with similar HBV prevalence, but anti-HBs in vaccinated individuals were in the expected range. It is important to promote HBV vaccination and awareness among medical students, due to their exposure risk.

Levels and correlates of knowledge about cancer risk factors among 13,293 public school students in Morelos, Mexico.

BACKGROUND: Data on young people's knowledge about cancer prevention are not currently available for many populations, including Mexican young people, although cancer is the second most common cause of death among the Mexican population. METHODS: A questionnaire was applied to 13,293 public school students aged 11-24 years in Morelos, Mexico. A knowledge-based scale was constructed from survey answers about risk factors for cancer. Data were analyzed using multivariate logistic multinomial models. RESULTS: Knowledge levels were low: 78% of male and 74% of female students had only wrong answers to questions about risk factors for cancer. A significant dose-response gradient was observed between age and knowledge of cancer risk factors (P < 0.001), with a higher prevalence in young women at all ages (female students OR 4.6, 95% CI 3.81-5.66). Students 18 years old and older knew more than 13-year-olds (OR = 2.39; 95% CI 1.89-3.01). Sexually active students (OR 2.10; 95% CI 1.70-2.58), especially those who consistently used condoms (OR 2.84; 95% CI 1.00-8.07), knew more about cancer prevention. Tobacco smoking was the most frequently recognized cancer risk factor, and smokers also recognized this as an important cause of cancer (OR 1.37; 95% CI 1.44-2.52). CONCLUSIONS: Our results reveal a poor level of knowledge about cancer prevention among adolescents. These data are the first step in the development of an intervention based on empirical findings that will be susceptible to evaluation.