HIV-1 and other sexually transmitted infections in a cohort of female sex workers in Chiang Rai, Thailand.

OBJECTIVES: To determine demographic and behavioural factors and sexually transmitted infections (STIs) associated with prevalent HIV-1 infection among brothel based and other female sex workers (FSWs) in Chiang Rai, northern Thailand. METHODS: Data were collected from questionnaires, physical examinations, and laboratory evaluations on Thai FSWs enrolled in a prospective cohort study in Chiang Rai, Thailand, from 1991 to the end of 1994. RESULTS: HIV-1 seroprevalence was 32% among 500 women: 47% for 280 brothel workers and 13% for 220 other FSWs (p < 0.001); 96% of infections were due to HIV-1 subtype E. At enrolment, other STIs were common: chlamydia, 20%; gonorrhoea, 15%; active syphilis (serological diagnosis), 9%; genital ulcer, 12%; seroreactivity to Haemophilus ducreyi, 21%, and herpes simplex virus type 2 (HSV-2), 76%. On multiple logistic regression analysis, HIV-1 was associated with brothel work, birth in upper northern Thailand, initiation of commercial sex at < 15 years of age, syphilis, HSV-2 seropositivity, and genital ulcer. CONCLUSIONS: Young Thai FSWs working in brothels in northern Thailand in the early phase of the HIV epidemic have been at very high risk for HIV-1 infection and several other STIs. Programmes are needed to prevent girls and young women from entering the sex industry and to reduce the risk of infection with HIV-1 and other STIs.

Growth of children according to maternal and child HIV, immunological and disease characteristics: a prospective cohort study in Kinshasa, Democratic Republic of Congo.

BACKGROUND: Most HIV-infection in children occurs in sub-Saharan Africa where antiretroviral therapy is seldom available. This study compares the growth progression and retardation of HIV-infected and uninfected children in the Democratic Republic of Congo (formerly Zaire). It estimates the risk for child growth retardation according to child and maternal immunological factors, severity of maternal and child illness, and maternal socioeconomic and marital status. METHODS: In a prospective cohort study of 258 children born to HIV seropositive mothers and 256 children of seronegative mothers in Kinshasa, Congo, the growth in length, weight, and weight-for-length of infected children (n = 68), uninfected children born to seropositive mothers (n = 190), and uninfected children born to uninfected mothers (n = 256) was compared. Serological, anthropometric and other clinical measures were collected monthly from 3-12 months and bi-monthly during the second year of life. Polymerase chain reaction for HIV was performed on bloods drawn at 2 days and 3 months post partum. Length-for-age, weight-for-age, and weight-for-length mean z-scores against National Center for Health Statistics (NCHS) reference data were calculated, and Cox proportional hazards models were used to estimate the risk of falling below -2.00 z-scores as a function of child and maternal immunological, clinical and sociodemographic variables. RESULTS: There was no difference in mean length-for-age at birth between HIV-infected (Group 1) children, uninfected children of infected mothers (Group 2) or Control children, but by 3 months old, HIV-infected children were shorter than both Group 2 and Controls. In weight-for-age and weight-for-length, Group 1 infants were lighter and more wasted at birth and onwards. Group 2 newborns were lighter than Controls at birth, but by three months they had caught up to Controls in both length and weight and remained the same as Controls thereafter. The odds of falling below -2.00 z-scores by 20 months for length, weight, and weight-for-length for HIV-infected children compared to uninfected children were 2.10, 2.84, and 2.56 respectively. Both HIV-infection and associated illnesses were factors associated with child stunting, underweight and wasting. The mother's age, socioeconomic status, presence of father, stage of illness and immune status had no detectable effect on the child's growth in the first two years of life. CONCLUSION: The HIV-infected children in Congo with no access to antiretroviral therapy were stunted, underweight, and wasted compared to same age uninfected children. Both HIV infection and HIV-associated signs and symptoms, not maternal immunological or socioeconomic circumstances, placed children at risk for growth retardation.

Utility of tuberculin and anergy skin testing in predicting tuberculosis infection in human immunodeficiency virus-infected persons in Thailand.

SETTING: Chiang Rai, the northernmost province of Thailand, where extensive human immunodeficiency virus (HIV) transmission has resulted in a rapid increase in tuberculosis. OBJECTIVE: To assess the utility of tuberculin and anergy skin testing to identify latent Mycobacterium tuberculosis infection in HIV-infected persons. DESIGN: A cross-sectional study and analysis were conducted to examine reactivity to tuberculin and two control antigens (mumps and candida) in HIV-negative and HIV-positive blood donors and female sex workers. RESULTS: HIV-positive persons had markedly decreased tuberculin reactivity; 14%, 19%, and 40% had an induration of > or = 10 mm, > or = 5 mm, > or = 2 mm, respectively, while 51% of 525 HIV-negative persons had an induration of > or = 10 mm (P < 0.001). Mumps and candida positivity (reactions of > or = 3 mm) were found in 94% and 78% of HIV-negative persons compared with 72% and 61% of HIV-positive persons, respectively (P < 0.001). Although HIV-positive persons had markedly less tuberculin reactivity even at higher CD4+ cell counts (> 400 cells/microL), reactivity to mumps and candida was present in more than half of HIV-positive persons with low CD4+ cell counts (< or = 200 cells/microL). Reaction to control antigens did not predict tuberculin reactivity. CONCLUSION: In this setting, tuberculin and anergy skin testing have a low predictive value in detecting M. tuberculosis infection in HIV-infected persons, and therefore such testing has a limited role in identifying HIV-infected persons who may benefit from tuberculosis preventive therapy programs.

Estimating the timing of mother-to-child transmission of human immunodeficiency virus in a breast-feeding population in Kinshasa, Zaire.

Breast-fed infants born to human immunodeficiency virus (HIV)-infected mothers in Kinshasa, Zaire, were monitored a mean of 18 months. HIV infection in infants was determined by polymerase chain reaction (PCR), HIV culture, or ELISA. PCR test results for HIV DNA on venous blood drawn from children ages 0-2 days and 3-5 months were used to estimate proportions of mother-to-child transmission and transmission risks during the intrauterine, intrapartum/early postpartum, and late postpartum periods. Among 69 HIV-infected children (26% of the cohort), 23% (95% confidence interval [CI], 14%-35%) were estimated to have had intrauterine, 65% (CI, 53%-76%) intrapartum/early postpartum, and 12% (CI, 5%-22%) late postpartum transmission. The estimated risks for intrauterine, intrapartum/early postpartum, and late postpartum infection, respectively, were 6% (16/261; CI, 4%-10%), 18% (45/245; CI, 14%-24%), and 4% (8/189; CI, 2%-8%). These results support earlier studies indicating that most transmission occurs during labor and delivery or in the early postpartum period and that the risk of HIV transmission through breast-feeding during the postpartum period is substantial.

Cost-effectiveness of short-course zidovudine to prevent perinatal HIV type 1 infection in a sub-Saharan African Developing country setting.

OBJECTIVE: To evaluate the cost-effectiveness of a short-course zidovudine program to prevent perinatal transmission of human immunodeficiency virus (HIV) type 1 in sub-Saharan African country settings. DESIGN AND SETTING: Several clinical trials of short-course zidovudine during pregnancy for prevention of perinatal transmission of HIV are under way in developing countries in sub-Saharan Africa. A decision model was used to examine the cost-effectiveness of zidovudine programs in a hypothetical 1-year birth cohort in a sub-Saharan African setting from the perspective of the health care system and of society. A completed short course of zidovudine was assumed to reduce perinatal HIV transmission from 25% to 16.5%, approximately one half of the effect of the longer-course zidovudine. Estimates of program costs, lifetime HIV-related health care costs, and lost productivity costs were derived from the published literature and from preliminary data available from sites of planned clinical trials. Sensitivity analyses were conducted on all relevant parameters. MAIN OUTCOME MEASURES: Medical costs, lost productivity costs, program costs, cost savings, and incremental cost-effectiveness, expressed as cost per infant HIV infection prevented. RESULTS: The model estimated that a national zidovudine program in a setting with 12.5% HIV seroprevalence would reduce perinatal HIV incidence by 12% (4.9 infections per 1000 births). The costs to the health care system would be $3748 per infant HIV infection prevented. When productivity losses were included in the model, the cost decreases to $1115 per infant HIV infection prevented. The cost to implement a national zidovudine program including the cost of counseling, testing, and drugs, would be $2 million per 100,000 births or $20 per pregnant woman. In the base case, decreases in the cost of counseling and testing and increases in maternal HIV prevalence, zidovudine efficacy, and medical and lost productivity costs improved cost-effectiveness of the zidovudine program. CONCLUSIONS: Assuming demonstrable efficacy of short-course zidovudine prevention of perinatal HIV, a national perinatal HIV prevention program with zidovudine in most sub-Saharan African country settings would reduce the incidence of infant HIV infection and, in some settings, provide societal savings; however, substantial initial investment in such programs will be required. Where health care resources are limited, as in these regions, allocation of resources to a perinatal zidovudine program will need to be considered in the context of resources required for other pressing medical care needs.

Rapid increase in HIV-related tuberculosis, Chiang Rai, Thailand, 1990-1994.

OBJECTIVE: Chiang Rai, the northernmost province of Thailand, has experienced an explosive HIV epidemic since 1989. This study assessed the impact of HIV infection on tuberculosis (TB) in the area. METHODS: We analyzed the incidence of reported TB in the province from 1982 through 1993 and TB registry data at Chiang Rai Hospital from 1985 through 1994. RESULTS: Following a steady decline in reported TB from 1982 through 1991, the incidence of TB increased sharply after 1991. TB registry data from Chiang Rai Hospital, which began confidential HIV testing in October 1989, indicated a steady and rapid increase in the number and proportion of HIV-seropositive TB patients from four (1.5% of all TB patients) in 1990 to 207 (45.5%) in 1994 (P < 0.001). Compared with HIV-negative TB patients, HIV-positive TB patients were more likely to be men, aged 20-39 years and have extrapulmonary TB (P < 0.001). Treatment completion rates were similar. Twelve months after beginning TB treatment, HIV-positive TB patients had a mortality rate of 68.6% [95% confidence interval (Cl), 62.7-74.3] compared with 10.0% (95% Cl, 8.3-12.1%) in HIV-negative patients (P < 0.001). CONCLUSION: Thailand and other Asian countries where HIV is spreading rapidly must promptly address the dual epidemic of TB and HIV in order to reduce preventable morbidity and mortality.

Impact of the HIV epidemic on trends in tuberculosis in Abidjan, Côte d'Ivoire.

SETTING: West African capital city with excellent, population-based notification of tuberculosis cases during a decade with a rapidly emerging HIV epidemic. OBJECTIVE: To evaluate the impact of the HIV epidemic on tuberculosis in Abidjan, Côte d'Ivoire. DESIGN: Review of data on all cases of tuberculosis registered in the city in alternate years from 1981 to 1991 and calculation of population-based rates using census data. Also, systematic study of HIV seroprevalence among tuberculosis patients in 1989 and 1991. RESULTS: In 1981, several years before any health consequences of HIV were discernible in Abidjan, the incidence of tuberculosis was 155 per 100,000. By 1991, the rate of tuberculosis among HIV-seronegative persons had decreased by 38% to 96 per 100,000; however, 43.6% of tuberculosis patients were HIV-infected, and the incidence of tuberculosis among HIV-infected persons was 1104 per 100,000 (relative risk 11.5, 95% CI 10.8-12.3), yielding an overall observed incidence of tuberculosis of 159 per 100,000 population. The population attributable risk of tuberculosis due to HIV infection increased from 36% to 40% between 1989 and 1991. CONCLUSIONS: The HIV epidemic has reversed the expected steep decline in tuberculosis in Abidjan over the past decade, and the impact of HIV infection on the incidence of tuberculosis may be accelerating.

Diagnóstico del sarampión según la definición de casos clínicos en zonas donde el dengue es endémico: repercusiones para la vigilancia y el control del sarampión / Diagnosis of measles by clinical case definition in dengue-endemic areas: implications for measles surveillance and control

En muchos países la vigilancia del sarampión depende, en gran medida, de la definición estándar de un caso clínico; sin embargo, los signos y síntomas clínicos del sarampión son similares a los del dengue. Por ejemplo, en 1985 se confirmó mediante exámenes serólogicos que 22 de 94 (23 por ciento) casos de enfermedad eruptiva cuyas características coincidían con la definición de casos clínicos de sarampión en Puerto Rico era, de hecho, sarampión, pero que otros 32 (34 por ciento) eran casos de dengue. El análisis retrospectivo efectuado en los laboratorios de los Centros para el Control de Enfermedades en San Juan también revelo que por lo menos 28 por ciento de todos los casos de dengue confirmados mediante pruebas de laboratorio en Puerto Rico en 1985 se ajustaban a la definición de casos clínicos de sarampión. Si suponemos que la eficacia verdadera (EV) de la vacuna antisarampionosa es de 90 por ciento, los casos de dengue que han sido confirmados en el laboratorio y que coinciden con la definición de casos clínicos de sarampión reducen la EV aparente de dicha vacuna a solo 64 por ciento (lo que representa una reducción de 29 por ciento en relación con la EV verdadera). Los resultados del estudio demuestran la importancia que tiene un sistema de vigilancia basado en pruebas de laboratorio para planear actividades de control o eliminación del sarampión en zonas donde el dengue es endémico

Diagnóstico del sarampión según la definición de casos clínicos en zonas donde el dengue es endémico: repercusiones para la vigilancia y el control del sarampión / Diagnosis of measles by clinical case definition in dengue-endemic areas: implications for measles surveillance and control

En muchos países la vigilancia del sarampión depende, en gran medida, de la definición estándar de un caso clínico; sin embargo, los signos y síntomas clínicos del sarampión son similares a los del dengue. Por ejemplo, en 1985 se confirmó mediante exámenes serólogicos que 22 de 94 (23 por ciento) casos de enfermedad eruptiva cuyas características coincidían con la definición de casos clínicos de sarampión en Puerto Rico era, de hecho, sarampión, pero que otros 32 (34 por ciento) eran casos de dengue. El análisis retrospectivo efectuado en los laboratorios de los Centros para el Control de Enfermedades en San Juan también revelo que por lo menos 28 por ciento de todos los casos de dengue confirmados mediante pruebas de laboratorio en Puerto Rico en 1985 se ajustaban a la definición de casos clínicos de sarampión. Si suponemos que la eficacia verdadera (EV) de la vacuna antisarampionosa es de 90 por ciento, los casos de dengue que han sido confirmados en el laboratorio y que coinciden con la definición de casos clínicos de sarampión reducen la EV aparente de dicha vacuna a solo 64 por ciento (lo que representa una reducción de 29 por ciento en relación con la EV verdadera). Los resultados del estudio demuestran la importancia que tiene un sistema de vigilancia basado en pruebas de laboratorio para planear actividades de control o eliminación del sarampión en zonas donde el dengue es endémico

Se publica en inglés en Bull. WHO. Vol. 70(6), 1992

Diagnosis of measles by clinical case definition in dengue-endemic areas: implications for measles surveillance and control.

In many countries, measles surveillance relies heavily on the use of a standard clinical case definition; however, the clinical signs and symptoms of measles are similar to those of dengue. For example, during 1985, in Puerto Rico, 22 (23%) of 94 cases of illnesses with rashes that met the measles clinical case definition were serologically confirmed as measles, but 32 (34%) others were serologically confirmed as dengue. Retrospective analysis at the San Juan Laboratories of the Centers for Disease Control showed also that at least 28% of all laboratory-confirmed cases of dengue in Puerto Rico in 1985 met the measles clinical case definition. If the true measles vaccine efficacy (VE) is assumed to be 90%, the occurrence of laboratory-confirmed dengue cases that meet the measles clinical case definition results in a reduction of the apparent measles VE to only 64% (a 29% relative reduction from the true VE). The results of the study demonstrate the importance of a laboratory-based surveillance system in measles control or elimination efforts in dengue-endemic areas.

PIP: In many countries, measles surveillance relies heavily on the use of a standard clinical case definition; however, the clinical signs and symptoms of measles are similar to those of dengue. For example, during 1985, in Puerto Rico. 22 (23%) of 94 cases of illnesses with rashes that met the measles clinical case definition were serologically confirmed as measles, but 32 (34%) others were serologically confirmed as dengue. Retrospective analysis at the San Juan Laboratories of the Centers for Disease Control showed also that at least 28% of all laboratory-confirmed cases of dengue in Puerto Rico in 1985 met the measles clinical case definition. If the true measles vaccine efficacy (VE) is assumed to be 90%, the occurrence of laboratory-confirmed dengue cases that meet the measles clinical case definition results in a reduction of the apparent measles VE to only 64% (a 29% relative reduction from the true VE). The results of the study demonstrate the importance of a laboratory-based surveillance system in measles control or elimination efforts in dengue-endemic areas. (author's)

Rapid Nutrition Surveys: How Many Clusters are Enough?

On the basis of theoretical considerations, population-based nutrition surveys of 30 clusters of 30 children should provide reasonably valid estimates of the prevalence of malnutrition with at least 95 per cent confidence that the estimated prevalence differs from the true value by no more than 5 per cent. In areas of famine in Africa, where an urgent need often exists for rapid nutritional assessment to determine the extent and severity of the problem, visiting 30 sites is often logistically difficult. To determine the effects of using fewer than 30 clusters on the validity and precision of the estimated level of undernutrition, we used data from the 1983 Swaziland National Nutrition Survey and from rapid nutrition surveys performed in 1984 and 1985 in Burkina Faso, Guinea, and Niger. Fewer than 30 clusters may result in point prevalence estimates that differ dramatically from the true prevalence and, in most instances, are less precise. In contrast, little is gained by collecting more than 30 clusters. In summary, around 30 clusters provides relatively valid and precise estimates of the prevalence of undernutrition, and every effort should be made to obtain the logistic support required to study this number of clusters.

The burden of acute respiratory infection due to measles in developing countries and the potential impact of measles vaccine.

Measles is a major cause of acute lower respiratory infection (ALRI) in developing countries. Hospital and community-based studies of ALRI have found that measles accounts for 6%-21% of the morbidity and 8%-93% of the mortality due to ALRI. Although live attenuated measles vaccine is one of the most effective vaccines in use today, measles has not been controlled in many parts of the world, primarily because the levels of vaccine coverage required to interrupt measles transmission have not been achieved. In addition, in some areas, a large percentage of cases of measles occur in infants who are younger than the age recommended for vaccination. Recent studies suggest that the Edmonston-Zagreb measles vaccine may be more immunogenic than other vaccine strains in young infants. A substantial proportion of ALRI could be prevented by increasing measles vaccine coverage and by the use of particular vaccine strains in younger children.

Identifying the malnourished within Peru: regional variation in the performance of a nutrition indicator.

Malnourished children may also have siblings at increased risk of poor health. Early identification of siblings at risk could lead to timely intervention to prevent the development of malnutrition or other potentially life-threatening events. In a nationwide survey conducted in Peru in 1984, stunting in an older sibling (defined as height/age less than or equal to 3.00 SD of the NCHS/CDC reference median) was evaluated as an indicator for stunting in a target sibling (next youngest) sibling) (n = 3284). The prevalence of stunting was much higher in target siblings who had an older sibling with stunting compared to those whose older sibling was not stunted, with prevalence ratios of 8.5 in Lima, 4.7 in urban areas, and 2.5 in rural areas. Screening indices (sensitivity, specificity, and predictive value positive) also showed marked variation across regions. The variation in this indicator's performance across regions demonstrates the importance of evaluating screening tools within the populations where they will be applied. Regional variations in the performance of malnutrition indicators should be anticipated because malnutrition is the result of a complex, multifactorial process.

Prevención y control del sarampión en situaciones de emergencia / Prevention and control of measles in emergency situations

Prevention and control of measles in emergency situations

Surveillance and control of meningococcal meningitis epidemics in refugee populations.

Epidemics of communicable diseases pose a direct threat to refugee and internally displaced populations, and could lead to high mortality rates and a disruption of basic health care services. Several large refugee populations live in regions of high meningococcal disease endemicity and their camps are at risk for outbreaks of meningococcal meningitis. Surveillance in these camps allows early detection and control of impending outbreaks. Confirmation of meningococcal disease can be performed under field conditions using simple techniques, such as latex agglutination. Isolates should be obtained for serogroup confirmation and antibiotic sensitivity studies at reference laboratories. Serogroup information is used to determine the risk of widespread epidemic disease and the utility of available vaccines. During epidemics, treatment regimens should be standardized, preferably with an effective single-dose antibiotic. Mass vaccination campaigns should be initiated, the populations at high risk being targeted for vaccination as quickly as possible. When the risk of epidemic disease is deemed to be high, preemptive vaccination may be warranted. Daily surveillance using a simple case definition is essential during an epidemic to determine the effectiveness of control measures and to delineate high-risk groups for vaccination or chemoprophylaxis. Many of these recommendations can be applied also to other populations in developing countries.

Prevención y control del sarampión en situaciones de emergencia / Prevention and control of measles in emergency situations

Prevention and control of measles in emergency situations

Se publica en ingles en el Bull. WHO 67(4), 1989