A dengue virus serotype-1 DNA vaccine induces virus neutralizing antibodies and provides protection from viral challenge in Aotus monkeys.

A DNA vaccine that expresses the premembrane/membrane (prM) and envelope (E) genes of dengue virus serotype-1 was tested for immunogenicity and protection against dengue-1 virus challenge in Aotus nancymae monkeys. The vaccine, in 1 mg doses, was administered intradermally (i.d.) to three monkeys and intramuscularly (i.m.) to three others. For controls, a 1 mg dose of vector DNA was administered i.d. to two monkeys and i.m. to one. All animals were primed and then boosted at one and five months post priming. Sera were collected monthly and analyzed for dengue-1 antibodies by enzyme linked immunosorbent assay (ELISA) and plaque reduction neutralization test (PRNT). Dengue-1 antibodies were detectable in the sera from i.d. and i.m. vaccine inoculated animals one month after the first boost and peaked one month after the second boost. The antibody levels from sera of animals that received the vaccine via the i.d. route were twice those from sera of animals that received the vaccine via the i.m. route. Six months after the second boost all inoculated and two naive monkeys were challenged with 1.25x10(4) plaque forming units (PFU) of dengue-1 virus. Two vaccine immunized animals were protected from viremia while the others showed a reduction in viremia. The mean days of viremia were 1 and 1.3 for the animals that were immunized with the vaccine via the i.d. or i.m. route, respectively vs 4 and 2 mean days of viremia in the animals inoculated with control DNA. Naive animals were viremic for an average of 4 days. All of the three control monkeys that received control DNA inoculum by either the i.d. or i.m. route had an intermittent viremia pattern with one or more negative days interspersed between the positive days. This pattern was not observed in any of the vaccine recipients or the naïve control monkeys. These results demonstrate that DNA immunization is a promising approach for the development of dengue vaccines and that A. nancymae monkeys are suitable for dengue vaccine trials.

The epidemiology of dengue virus infection among urban, jungle, and rural populations in the Amazon region of Peru.

The first confirmed outbreak of dengue fever in Peru occurred during 1990 in Iquitos, a city of approximately 300,000 residents in the Amazon region. Because of the apparent establishment of endemic transmission of this mosquito-borne viral disease following the outbreak, epidemiologic studies were initiated in 1992. Blood specimens and data on demographic, environmental, and medical history factors were collected from volunteers in an urban sector of Iquitos, in a rural area on the outskirts of Iquitos, and in three nearby jungle communities. A follow-up blood specimen was obtained approximately one year later from a sample of subjects. Sera were tested for dengue IgG antibody by an enzyme-linked immunosorbent assay, and specificity was verified using a plaque-reduction neutralization test. Dengue antibody prevalence was 66% in the urban population, 26% in the rural population, and 32-67% in the three jungle areas. A significant association was found between age and antibody prevalence, with a steady increase in prevalence from 18% among subjects less than five years of age to greater than 90% for subjects more than 50 years old. Increased antibody prevalence also was associated with urban and jungle residence and with a piped source of household drinking water. Seroconversions were documented in four of five surveyed communities. These results indicate that dengue virus transmission continues in and around Iquitos and suggest that transmission also occurred prior to the 1990 epidemic.

Gender differences in sexual practices and sexually transmitted infections among adults in Lima, Peru.

OBJECTIVES: This study examined the prevalences of antibodies to Treponema pallidum, Chlamydia trachomatis, and herpes simplex virus type 2 in a sample of Peruvian adults. METHODS: Among adults seeking health certification in Lima, Peru, 600 were randomly selected to undergo interviews and serologic testing. RESULTS: Men's reported mean lifetime number of partners (10.6) far exceeded women's (1.1), yet antibody to sexually transmitted infection pathogens among sexually experienced participants was 2.8 times more prevalent among women than among men. Among men, female sex workers accounted for 37% of recent partners, and only sex with female sex workers while using condoms less than half of the time was independently associated with antibody (odds ratio = 3.6, 95% confidence interval = 1.5, 8.8). among women, number of partners was associated with any sexually transmitted infection antibody, while intercourse before 18 years of age was associated with C trachomatis antibody. At every level of perceived risk, sexually transmitted infection antibody was more frequent among women. CONCLUSIONS: Men having unprotected sex with female sex workers had the greatest risk of acquiring infections and (by inference) of transmitting them to women.

Human T cell lymphotropic virus type I infection among female sex workers in Peru.

Four hundred female sex workers attending a sexually transmitted disease clinic in Lima, Peru, were interviewed for demographic information and medical, contraceptive, and sexual practice histories. Cervical cultures were done for Neisseria gonorrhoeae and Chlamydia trachomatis, and serum was tested for antibodies to human immunodeficiency virus, human T cell lymphotropic virus type I (HTLV-I), Treponema pallidum, C. trachomatis, herpes simplex virus type 2 (HSV-2), and Haemophilus ducreyi. The prevalence of HTLV-I increased with duration of prostitution from 3.6% (< 3 years) to 9.3% (3-6 years) to 15.9% (> 6 years; P < .01). After adjustment for duration of prostitution, reduced risk of HTLV-I was significantly correlated with condom use for more than half of all sexual exposures for > 3 years (odds ratio [OR], 0.34; 95% confidence interval [CI], 0.13-0.89). Further adjusting for condom use, HTLV-I seropositivity was associated with C. trachomatis (OR, 3.7; 95% CI, 1.4-13.2) and with antibody to HSV-2 (OR, 3.7; 95% CI, 0.5-29.6). Thus, duration of prostitution, lack of consistent condom use, and past infection with C. trachomatis were significantly associated with HTLV-I seropositivity.

Chronic liver disease in Peru: role of viral hepatitis.

The prevalence of antibodies to hepatitis C virus (anti-HCV) was determined in 105 patients with biopsy-proven chronic liver disease and 128 comparison patients without any evidence of liver pathology living in Lima, Peru. Using a second-generation EIA screening and supplemental immunoblot assay, anti-HCV was detected in four of 13 patients with chronic hepatitis, in 11% of 85 patients with cirrhosis, and in none of seven patients with hepatocellular carcinoma. Only two (1.6%) comparison patients without liver disease had anti-HCV. Hepatitis B surface antigen (HBsAg) was found in 23% of patients with chronic hepatitis, 12% of patients with cirrhosis, and three of seven patients with hepatocellular carcinoma. There was no evidence of chronic viral hepatitis or alcohol abuse (reported by one-third of subjects) in 48% of chronic liver disease patients. These preliminary data suggest that among this South American population neither hepatitis B nor hepatitis C infection is the predominate cause of chronic liver disease and that other infectious or environmental factors may be important.

Three-year incidence study of retroviral and viral hepatitis transmission in a Peruvian prostitute population.

A Peruvian female prostitute population was evaluated over a 3-year period to determine the incidence and risk factors of retroviral and viral hepatitis transmission. At three survey periods, a questionnaire was administered and serum samples were obtained. A total of 966 subjects were studied, with 34% followed for 38 months, 22% followed for 18 months, and 44% evaluated just once. On initial evaluation, 3 (0.3%) had HIV-1 antibody, 170 (17.6%) had HTLV-I antibody, 578 (59.8%) had anti-HBc, and 7 (0.7%) had antibody to hepatitis C virus. The mean annual incidence of HTLV-I and hepatitis B infection was 1.6% and 4.7%, respectively. Univariate and logistic regression analysis of prevalence data indicated an association between sexual activity and HTLV-I and hepatitis B infection, but no independent risk factors were identified in cohort analysis. Parenteral risk factors were not associated with transmission, except for a small percentage of subjects who may have acquired hepatitis B infection from blood transfusions. These findings suggest that there is a high incidence of HTLV-I and hepatitis B infection from heterosexual contact in this female prostitute population.

Mosquitoes (Diptera: Culicidae) captured in the Iquitos area of Peru.

A mosquito capture program was initiated to study mosquito species and their potential for arboviral transmission in the Peruvian Amazon. More than 35,000 mosquitoes of 13 different genera and at least 25 species were captured in urban and sylvan sites in the Iquitos area. These findings represent the first published list of Peruvian mosquitoes since 1971 and the first such list from the Peruvian Amazon.

Sexual transmission of human T-lymphotropic virus type I in Peruvian prostitutes.

The epidemiology of HTLV-I infection in female prostitutes was studied in a survey of 395 prostitutes from Callao, Peru (the port city of Lima), 72 prostitutes from Iquitos, Peru (another port city on the Amazon River), and 510 prenatal clinic patients from Lima. Prostitutes reported a mean of 8.8 years (range, 1-39 years) of active prostitution and a mean of 205 sexual contacts during the month prior to the study. The percentage of prostitutes with HTLV-I antibody (21.8%) was significantly higher than patients attending a prenatal clinic (3.1%; P less than .0001). The prevalence of HTLV-I antibody increased steadily with age in prostitutes, but no age trend was noted in prenatal patients. By multiple logistic regression analysis, an independent association was found between HTLV-I seropositivity and a history of prostitution in Callao, age, and positive syphilis serology when all 977 study subjects were evaluated. When prostitutes alone were analyzed, the number of years of exposure as a practicing prostitute was associated with HTLV-I seropositivity after controlling for age. These data indicate a greatly increased risk of HTLV-I infection in prostitutes in Callao, Peru, and suggest an association between sexual activity and HTLV-I transmission.

The impact of human T-lymphotrophic virus type I/II infection on the prognosis of sexually acquired cases of acquired immunodeficiency syndrome.

Twenty (18%) of 111 Peruvian men with sexually acquired human immunodeficiency virus infection were found also to be infected with human T-lymphotrophic virus type I or II in a retrospective study. At the time of data evaluation, 75 patients had reached Centers for Disease Control stage IV (clinical acquired immunodeficiency syndrome) and had not received antiviral medication; mortality in this group was 63.3% (38/60) among patients infected with human immunodeficiency virus alone and 80% (12/15) in the dually infected group. Of the 50 patients who had died, survival time from onset of stage IV to death was shorter in the dually infected group (5.02 +/- 3.27 months) than in those with human immunodeficiency virus infection alone (10.07 +/- 4.42 months). In Peru, sexually acquired human immunodeficiency virus infection in men is often accompanied by human T-lymphotrophic virus type I/II infection, and dual retrovirus infection is associated with a shorter survival after onset of clinical acquired immunodeficiency syndrome.

Seroprevalence of hepatitis C antibody in Peru.

The prevalence in Peru of antibody to hepatitis C virus (anti-HCV) was determined in a survey of populations living in the northern jungle region and in groups at high risk of parenterally and sexually transmitted diseases. All sera were initially screened for anti-HCV using commercial first and second generation ELISAs; repeatedly reactive sera were further verified with a second generation immunoblot assay. Serum samples were also tested by ELISA for HBsAg, anti-HBs, and anti-HBc. None of 2,111 sera obtained in the survey of jungle residents was positive for anti-HCV by immunoblot assay. Twelve of 16 HIV-1 antibody positive hemophiliacs, one of 103 HIV-1 antibody positive homosexuals, and three of 602 HIV-1 negative registered female prostitutes were positive for anti-HCV. A high prevalence of total markers of hepatitis B infection was found in all subjects, especially in older subjects and groups at high risk of parenterally and sexually transmitted diseases. The findings of this study indicate that seropositivity for hepatitis C virus antibody is uncommon in Peru except in high risk groups and suggest that the epidemiology of hepatitis C differs substantially from hepatitis B.

Hepatitis B in a highly active prostitute population: evidence for a low risk of chronic antigenemia.

The epidemiology of hepatitis B in female prostitutes was studied in a cross-sectional survey of 467 prostitutes and 510 control prenatal clinic patients from Lima and Iquitos, Peru. Prostitutes reported a mean of 8.8 +/- 6.7 years of active prostitution and a mean of 205 +/- 137 sexual contacts in the month prior to the study. Hepatitis B surface antigen (HBsAg) was found in comparable percentages of prostitutes (1.7%) and controls (0.8%; P = .305). In contrast, seropositivity for both antigen and antibody markers (HBsAg, anti-HBs, or anti-hepatitis B core) was found in a significantly higher percentage of prostitutes than controls (67.0% vs. 10.0%; P less than .0001). By multivariate analysis, both prostitution (odds ratio [OR] 14.6) and the number of years of exposure as a prostitute (OR 3.2 for 10 years of exposure at age 35 years) were significantly associated with seropositivity for hepatitis B markers when adjusted for age. In this study, the prevalence of HBsAg was not substantially increased in highly active female prostitutes compared with the general population, even though hepatitis B transmission was greatly increased. These data suggest that in adult women with a high level of hepatitis B infection, hepatitis B antigenemia may not persist as frequently as previously indicated in studies of other populations.

Marcadores serológicos de hepatitis viral B en pacientes drogadictos del hospital Hermilio Valdizán, Lima, Perú

Estudio realizado en 36 pacientes drogadictos, en abril de 1988, internados en el Centro de Rehabilitación de Farmacodependientes de Naña (Hospital Hermilio Valdizán), con el objeto de establecer la magnitud de la infección por el virus de Hepatitis B (VHB) en ellos, considerando que no eran usuarios de drogas intravenosas y, de acuerdo a los resultados, evaluar los posibles médios de su transmisión. Se utilizaron dos marcadores serológicos: el AgsHB y el HBc. Adicionalmente , se usó el anticuerpo contra el virus de la inmmuno-deficiencia humana (Anti-VIH); empleando la técnica de ELISA. Los resultados mostraron positividad del AsHB en 5 casos (13,8%) y Anti-HBc en 6 casos (16,6%). El Anti-VIH fue negativo en los 36 casos. El nivel de positividad del AgsHB sería alto en comparación al de la población general adulta de la costa peruana. Esto clasificaría a los drogadictos como grupo de riesgo con evidentes consecuencias personales y posibilidad de transmitir la infección a otras personas. Las vías de transmisión serían variadas, resaltando ciertas características de la vida sexual en varios de ellos, aspecto considerado también por otros investigadores como un riesgo frecuente de transmisión no parenteral del VIH en drogadictos

Diagnosis of group A streptococcal infections directly from throat secretions.

The diagnosis of group A streptococcal disease still relies on isolation of group A streptococcal strains on sheep blood agar followed by presumptive identification based on bacitracin sensitivity or the results of the more precise serogrouping methods such as the Lancefield precipitin test. A technique that would permit rapid identification of streptococcal infections directly from throat secretions would allow immediate appropriate antimicrobial therapy for the management of streptococcal infections to be started. We have been able to identify soluble group A antigen directly from throat secretions by using a latex agglutination test. In a clinical trial in which latex (Streptex group A) and conventional culturing techniques were used, 53 throat secretion cultures were tested: 26 were positive by both procedures, 5 were positive by culture only, 3 were positive by the latex agglutination test only, and 19 were negative by both tests.

Clinical and serologic study of four smallpox vaccines comparing variations of dose and route of administration. Basic study and laboratory standardization.

The present four-center collaborative study was undertaken in an attempt to define the best vaccine and/or vaccination procedure for use in areas of the world that are free of smallpox. The study was designed to compare the effect of different vaccinial strains, viral concentrations, and routes of administration on the morbidity and antibody response associated with primary vaccination and standard challenge revaccination. Primary vaccinations were performed on 1,585 children; 49.6% of the children were vaccinated by the percutaneous route, and 50.4% received vaccine subcutaneously. The overall age and sex distributions of percutaneous and subcutaneous vaccinees were comparable, but there were marked differences in participants among the four study centers. Vaccines in Kentucky had a greater mean age; the greatest number of Negroid children were enrolled in St. Louis, and more of them were vaccinated by the subcutaneous route; and the dropout rate was much greater in San Diego and Colorado. An analysis of comparative interlaboratory serologic procedures with the use of 20 coded duplicate samples of serum revealed good agreement in the hemagglutination-inhibition test; results of neutralization tests had greater variability of mean titers. On duplicate samples of serum from study participants there was generally good correlation between each of the four study centers and the Center for Disease Control's reference laboratory in titers of hemagglutination-inhibiting antibody. In contrast, 38% of the neutralization titers determined at the four study centers were greater than or equal to 0.67 log10 higher than the respective titers noted at the Center for Disease Control.

Milker's nodules. Pathogenesis, tissue culture, electron microscopy, and calf inoculation.

We report the occurence of milker's nodules in nine patients. In man, the disease goes through maculopapular, target, acute weeping, nodular, papillo-matous, and regressive stages. Papular and papillomatous stages were noted following vaccination of a calf with material prepared from a human lesion. A viral agent was isolated in cultures of bovine kidney cells and human skin fibroblast cells. Cytoplasmic inclusions were frequently seen in the infected bovine kidney cells. Electron microscopy revealed viroplasm, partially encapsulated viroplasm, encapsulated viroplasm, and oval particles with spires around the outside.