Molecular detection of respiratory syncytial virus in postmortem lung tissue samples from Mexican children deceased with pneumonia.

BACKGROUND: Respiratory syncytial virus (RSV) is the major viral cause of severe respiratory infections in children younger than 2 years of age. Nevertheless there are not enough epidemiologic data about the role of RSV as a cause of infantile mortality from pneumonia, mainly in young children from developing countries Aim. To determine the frequency of RSV infection in lung tissue samples from Mexican children deceased with pneumonia, by reverse transcription (RT) and PCR. METHODS: Postmortem lung tissue samples from 98 children younger than 2 years of age who died of pneumonia during the period of 1989 to 1997 were studied. Paraffin was removed with xylene from 10-microm lung sections, the total RNA was extracted and complementary DNA was obtained by RT reaction. A nested PCR with the use of oligonucleotides specific for the F glycoprotein gene was developed. Samples negatives for RSV were tested for the absence of polymerase inhibitors and for complementary DNA integrity. RESULTS: Twenty-nine of the 98 (30%) children deceased with pneumonia were positive for RSV by RT-PCR; 8 were detected from 13 (62%) children with histopathologic diagnosis of viral pneumonia and 21 from 85 (25%) children with histopathologic diagnosis of bacterial pneumonia (P = 0.018). There was no significant difference in RSV infection according to age groups or seasonal pattern. CONCLUSIONS: RSV infection is frequent in Mexican children younger than 2 years of age who died of pneumonia. Although RSV was more common in viral pneumonia, mixed infections with RSV and bacterial pneumonia were also common.

Infection of pregnant women with hepatitis B and C viruses and risks for vertical transmission.

Pregnant women infected with hepatitis B and C viruses pose a risk for infecting their newborn infants by vertical transmission. We studied 6,253 pregnant women aged 12-49 years for infection with hepatitis B (HBV) and C (HCV) viruses. Infection was diagnosed by measuring IgG antibodies against HBc, HBs, HBe, as well as IgM-HBc and HCV viral antigens with commercially available immunoassay kits. HBV infection was detected in 113 cases (1.8%), and prevalence was significantly higher (2.4%) in a group of women with a high-risk pregnancy who were attending a perinatology hospital than in healthy pregnant women (1.67%, p < 0.05). Infection with HBV was significantly higher in women older than 30 years old (p < 0.05). HBsAg was found in blood, colostrum and vaginal exudate of two pregnant women; HBsAg was detected in the gastric aspirate but not in the blood of the two newborn infants. HBeAg and IgM-HBc were not detected in any of the samples. DNA-HBV was detected in serum of seven women, and DNA-HBV was detected in the gastric aspirate of only one of the newborns. HCV infection was diagnosed in three out of 111 women with markers for HBV infection (2.7%), and in 6 out of 1,000 women without these markers (0.6%). Anti-HCV antibodies were found in the serum of six of their infants during up to six months of age. Infants were monitored for one year and none of them developed any sign of hepatic disease. These results suggest that special attention should be paid to women older than 30 years and with a high-risk pregnancy, as they are at a higher risk of HBV and HCV infections.

Comparison of five methods for the detection of measles specific immunoglobulin G antibody.

In this work we compare the sensitivity, specificity and predictive values of hemagglutination inhibition (HI), immunofluorescent assay (IFA), biotin-streptavidin immunofluorescent assay (B/SA-IFA), enzyme-linked immunosorbent assay (EIA) and plaque neutralization test (PN). This study includes serum samples from children taken before and after vaccination, children with clinically diagnosed measles and household contacts. EIA were the most specific and better serological diagnostic test. HI and IFA had high sensitivity but low specificity. An alternative to EIA is B/SAIFA, which is cheaper than EIA and can be used in the study of small outbreaks or in isolated cases.

[Prevalence of rubella virus antibodies in pregnant women in two zones of Valle de Mexico]. / Prevalencia de anticuerpos para el virus de rubéola en mujeres gestantes de dos zonas del Valle de México.

The aim of this study was to determine the prevalence of specific antibodies against rubella virus in pregnant women from Iztapalapa and Nezahualcóyotl areas of the valley of Mexico, in order to evaluate susceptibility to this virus in these areas. Serum samples collected from 5535 women between 15 and 44 years old were studied by the hemaglutination inhibition test. 92.6% of positivity was obtained and no significant difference was observed between different age groups. The prevalence of rubella antibodies in pregnant women was 92.4% for Iztapalapa zone and 92.8% for Nezahualcóyotl. The titles of antibodies against rubella virus more frecuently presented were 1:16 (36.3%) and 1:32 (29.6%). The data obtained in this study suggest that women attending Medical Services of the Mexican Institute of Social Segurity in reproductive age from the Iztapalapa and Nezahualcóyotl areas, do not need massive vaccination against rubella virus.

[Protection of health personnel against hepatitis B by DNA recombinant vaccine]. / Protección contra hepatitis B en trabajadores de salud con vacuna de DNA recombinante.

Hepatitis B (HVB) is a worldwide spread health problem. It has been assessed that there are more than 300 millions of carriers. HVB has a special concern for health care workers (HCW's) due to the high risk among them of getting the infection in clinic-setting areas. According to some estimation, the risk for hepatitis B among HCW's is 2 to 10 times higher than the risk for general population. The risk is related to the degree of direct contact with blood and body fluids, as well as, with the frequency of traumatic exposure in the work place. The control of this infection is based on the observance of universal precautions and the vaccination, since there is not treatment against this disease. The results of an efficacy-evaluation of DNA recombinant vaccine against hepatitis B are reported; 174 HCW's were studied; three dosages of vaccine were administered (0.1st and 6th month) by I.M. via. In addition, three serum samples were collected at 0, 1st and 9th month after vaccine administration. We did not find carriers of surface antigen of hepatitis B. With regards to seroconverted individuals we observed the following results: there were a satisfactory response to the vaccine in 163 individuals (93.7%); however, 8 (4.6%) persons did not reach titles of protective antibodies and 3 (1.7%) did not show seroconversion at all. Therefore, 11 persons (6.3% of the total) did not result immunized. The secondary reactions to the vaccines were low in frequency and mainly of local presentation. Among the study population we did not find chronic carries of hepatitis B.(ABSTRACT TRUNCATED AT 250 WORDS)

[Hepatitis B and delta: the prevalence of seroepidemiological markers in volunteer blood donors and their families]. / Hepatitis B y delta: prevalencia de marcadores seroepidemiológicos en donadores de sangre voluntarios y su grupo familiar.

41 volunteer blood donors and his relatives were studied in order to know about the prevalence of hepatitis B and D virus infections in selected groups. Frequency of HBsAg+ carriers was 0.34 per cent in the Centro Nacional de la Transfusión Sanguínea and 0.15 per cent in the Banco Central de Sangre, IMSS. Most of the HBsAg+ blood donors were 21 to 40 years old (87.8%); 21.9 per cent had IgM antibodies against HBc and just 2.4 per cent were HBeAg positive. Forty one (26.9%) of 152 relatives had one or more of the HBV markers, 3.9 per cent were HBsAg carriers and 1.3 per cent were HBeAg positive. In the infected relatives group 36.6 per cent were ancestory or brothers and just 14.6 per cent of wives were infected. None of the HBsAg+ blood donors or his relatives had antibodies against delta agent. These results support the fact that the frequency of asymptomatic carriers of HBsAg in the volunteer blood donors group is similar to he frequency in the general population and identifies the group of relatives as those with the highest risk to acquire HBV infection.

[The seroepidemiology of rubella in Mexican women. A national probability survey]. / Seroepidemiología de la rubéola en mujeres mexicanas. Encuesta nacional probabilística.

A rubella seroepidemiologic survey was carried out in a rural population to better understand the epidemiology of this infections disease in Mexico. 24,331 serum samples from women between 10 and 44 years old were collected during 1987-1988 from the 32 federal states. Samples were tested for Rubella Antibodies by use of hemagglutination inhibition with a titer 1:8 bring considered as positive; 79.96 per cent (CI 95%, 7.5-80.5%) of women were seropositive, seropositivity increased with age, from 69.26 per cent in the age group of 10 to 14 years old, to 87.84 per cent in the 40-44 age group. Seropositivity rates were lower in southern states than in northern states and, higher in urban areas that rural areas (82.4 vs 76.6%); statistical significative difference in seropositivity rates were found between girls less than 14 years of age in urban areas as compared to rural areas (74.7 vs 63.6%). Seropositivity rates were related to socioeconomic status only when high status group were compared lower status group (82.5 vs 77%). In addition, we observed a significative trend of increasing seropositivity as level of school education increased. In comparison to the 1974 national survey, this seroepidemiological survey showed a decreased seropositivity for all age groups, even with an increase in the number of susceptible women, particularly in the group less than 20 years old. This study offers seroepidemiologic information about rubella at a national and regional level.

Hepatitis A antibodies: prevalence and persistence in a group of Mexican children.

The prevalence of antibodies against hepatitis A virus (anti-HAV) was evaluated in sera from 275 asymptomatic infants and children under the age of five years and in 46 maternal-cord serum pairs, followed by sera obtained thereafter each month from the first to the fifth month of life in 29, 17, 9, 9 and 7 infants (a total of 163 serum samples). Anti-HAV was found in all cord blood sera, but its prevalence declined progressively to 0% among 19 infants aged eight months. Four (25%) of 16 children aged one year had positive anti-HAV and the antibody prevalence was 89% in children five years old. Recent hepatitis A infection shown by circulating anti-HAV immunoglobulin M was detected in five infants under the age of two months and with frequencies ranging from 19-67% in one- and five-year-old children. It was concluded that in children living in Mexico City, hepatitis A infections occur at an earlier age and at higher rates than in children in other cities, especially those in developed countries.

[Intrauterine infection in relation to the frequence of prematurity and congenital malformations]. / Infección intrauterina en relación con la frecuencia de prematurez y de malformaciones congénitas.

In order to find the relationship between intrauterine infection with frequency of prematurity and of congenital malformations, 1,016 newborns were studied and were divided into four groups: 324 normal babies, 606 prematures, 44 with malformations and 42 infected patients; the latter were confirmed through titration of serum antibodies. The first index of infection was the concentration of IgM greater than or equal to 28 mg. %; thus, the first groups showed evidence of infection in 0.9%; the second in 11%; the third in 40.9% and the fourth, in 100%.

[Neonatal infection and high IgM at birth]. / Infección neonatal e IgM elevada al nacimiento.

To determine the concentration of IgM to be used as intrauterine infection indicator, the sera of 2,906 newborns were studied. Five hundred and sixty-three (19.4%), showed high concentrations of IgM and out of 199 pair sera studied, serologic evidence of infection was found in 21.1%. Out of these cases, 80.9% showed no clinical disturbances during their first two months of life. The agents most frequently found responsible for intrauterine infection were cytomegalovirus, influenza A2 H-K, influenza B, parotiditis and rubella. Based on this study, we may conclude that determinations of high concentrations of IgM with the technique used is still a good index to detect intrauterine infections, specially considering that the clinical manifestations of disease may be minimal or may pass unnoticed during the first days of life and that by no means should this test be done instead of other clinical or laboratory studies to investigate such questions.