Ultrasound-derived fetal size nomogram for a sub-Saharan African population: a longitudinal study.

OBJECTIVES: To create a fetal size nomogram for use in sub-Saharan Africa and compare the derived centiles with reference intervals from developed countries. METHODS: Fetal biometric measurements were obtained at entry to antenatal care (11-22 weeks' gestation) and thereafter at 4-week intervals from pregnant women enrolled in a longitudinal ultrasound study in Kinshasa, Democratic Republic of Congo. The study population comprised 144 singleton gestations with ultrasound-derived gestational age within 14 days of the menstrual estimate. A total of 755 monthly ultrasound scans were included with a mean +/- SD of 5 +/- 1 (range, 2-8) scans per woman. Estimated fetal weight (EFW) was calculated at each ultrasound examination using the Hadlock algorithm. A general mixed-effects linear regression model that incorporated random effects for both the intercept and slope was fitted to log-transformed EFW to account for both mean growth and within-fetus variability in growth. Reference centiles (5(th), 10(th), 50(th), 90(th) and 95(th) centiles) were derived from this model. RESULTS: Nomograms derived from developed populations consistently overestimated the 50(th) centile EFW value for Congolese fetuses by roughly 5-12%. Differences observed in the 10(th) and 90(th) centiles were inconsistent between nomograms, but generally followed a pattern of overestimation that decreased with advancing gestational age. CONCLUSIONS: In low-resource settings, endemic malaria and maternal nutritional factors, including low prepregnancy weight and pregnancy weight gain, probably lead to lower fetal weight and utilization of nomograms derived from developed populations is not appropriate. This customized nomogram could provide more applicable reference intervals for diagnosis of intrauterine growth restriction in sub-Saharan African populations.

HIV-1 seroprevalence rates in women and relinquishment of infants to the state in St Petersburg, Russia, 2002.

The effectiveness of rapid HIV-1 testing and nevirapine prophylaxis for HIV-infected mothers without prenatal care has been shown. We found that from 1998 to 2002, HIV-1 seroprevalence in women giving birth in St Petersburg, Russia increased 100-fold: from 0.013% to 1.3% (p<0.0001). HIV-1 seroprevalence was 8% (114 of 1466) in women without prenatal care and 1% (376 of 37645) in those with prenatal care (p<0.0001). All 376 HIV-1-infected women with, and 41% (47 of 114) of HIV-1-infected women without prenatal care received intrapartum antiretroviral therapy (p<0.0001). In women who were HIV-1 positive, 26% (30 of 114) of those without prenatal care and 4% (13 of 371) of those with prenatal care relinquished their infants to the custody of the state, compared with 1% (354 of 37 621) of HIV-1-negative women (p<0.0001).

Reasons for the wide variation in reported rates of mother-to-child transmission of HIV-1.

PIP: The explanation of marked global variation (between 12 and 65%) in the rate of mother-to-child transmission (MCT) of HIV-1 both in developed and developing countries is inadequate. The risk of MCT ranges from one in eight to one in 1.5 pregnancies. There are marked methodological differences in the case definitions, study designs and diagnostic criteria in the various MCT investigations. Although most HIV-1 MCT appears to occur in the peripartum period, it can also occur in the intrauterine phase or immediately postpartum requiring diagnostic techniques that are not often available. Polymerase chain reaction or in situ hybridization tests for early diagnosis of MCT have been found to lack specificity for both HIV-infected and uninfected infants who are born to HIV-infected mothers and who remain HIV-seropositive during their first year of life. A second explanation for the wide variability derives from the varying case mix of any given maternal cohort. HIV infection during pregnancy and pregnant women with advanced HIV-induced immunosuppression are particularly infectious to their children. A third source of MCT variation results from selection bias in many MCT studies. It is not known whether the only mechanism of transmission in the perinatal period is transplacental or transmission occurs during delivery. Data suggest that delivery via Caesarean section halves the risk of MCT. Antiretroviral treatment (zidovudine) for HIV-infected mothers in the immediate prepartum and intrapartum period, followed by postpartum administration to their infants has reduced these infants' chance of MCT by as much as 50%. A recent study from Malawi demonstrated that HIV-1-seropositive women with vitamin A deficiency had a twofold greater risk of transmitting HIV-1 infection to their infants. The many biologic reasons for the wide variation in MCT make it unlikely that prevention will be possible through a single biologic and/or pharmacologic approach.^ieng

The epidemiology of perinatal transmission of HIV.

PIP: The range of issues in the epidemiology of perinatal infection with HIV covers prevalence of HIV in women, types of HIV transmission to the fetus and newborn, problems with testing for HIV infections in neonates, variations in effectiveness of transmission to infants, maternal, fetal and perinatal mortality. In the U.S. 75% of all pediatric AIDS cases are traceable to HIV-positive mothers, but numbers are small. In Central Africa, seroprevalence in women is about 5%, and perinatal HIV is significant. HIV has been demonstrated in fetal tissues and cord blood, indicating transmission in utero. Transmission at birth has not yet been documented. Transmission of HIV after birth, presumably via breastfeeding, has been shown in at least 8 cases. No information is available on HIV titers in breast milk. Diagnosis of HIV infection in newborns is problematic. Cord blood cultures, the p24 antigen test, and the in situ hybridization method are feasible but impractical in most clinics. The Western blot test for IgM-specific antibodies is not specific or sensitive enough for infants. A new method called [DNA] polymerase chain reaction (PCR) is capable of detecting acquired HIV infection, and may be useful in clinics, since it does not require radionuclides. In 11 studies the incidence of HIV infection in infants of seropositive mothers ranged from 8-65%. There is some indication that the stage of the HIV disease, and possibly socioeconomic status, of the mother affect the transmission of the virus. There is no indication that pregnancy worsens maternal HIV status, although there is a suggestion that mothers may worsen in the postpartum period. Several studies show increased incidence of low birth weight and prematurity, associated with higher infant mortality, in newborns of HIV-positive mothers. No effective programs of screening or counseling women at risk of HIV infection and pregnancy have been reported.^ieng

The effect of HIV-1 infection during pregnancy and the perinatal period on maternal and child health in Africa.

PIP: In 1989 the Global Program on AIDS (GPA) of the World Health Organization estimated that there were 2.5 million women and half a million children infected with HIV-1 in Africa. A study carried out in two maternities in Kinshasa, Zaire, in 1988 showed higher mortality rates in previously born children of seropositive mothers compared with children of seronegative mothers (43% vs. 32%, p 0.01). A case control study in Nairobi of patients admitted with an acute spontaneous abortion indicated that HIV-1 infection was significantly associated with spontaneous abortion (13.8% vs. 6.2%. p = 0.02). In another study from Nairobi the mean birth weight of infants born to seropositive mothers was slightly but significantly lower than the birth weight of infants with seronegative mothers (3090 vs. 3220 g, p = 0.005). In the Kinshasa study more infants born to HIV-1 seropositive mothers with symptomatic infection were delivered before 38 weeks of gestation compared with neonates of HIV-positive asymptomatic or seronegative women (18%, 12%, and 3%, respectively, p 0.01). In the Nairobi study abnormalities were noted in 115 stillborn neonates, and maternal HIV-1 infection (odds ratio of 2.7) was a contributory factor. Among the 68 live-born infants with HIV-1 seropositive mothers in the Kinshasa study, there were 29 (6.2%) neonatal deaths compared with 8 (1.3%) among infants of seronegative women (p 0.0001). In addition, chorioamnionitis was found significantly more often in the placentas of infants of HIV-1 seropositive mothers with AIDS than among placentas of infants born to asymptomatic seropositive women or seronegative controls (21.4% vs. 1.0% and 2.9%, respectively, p 0.01). In another Nairobi study in 1990 a single session of counseling of HIV-1 seropositive women did not seem to influence their subsequent condom use or reproductive behavior. Pregnancy seemed to accelerate the progression of the disease because of its immunosuppressive effect. The diagnosis of perinatal HIV infection has been difficult and the use of the polymerase chain reaction method has been the most sensitive test.^ieng

Mortality in HIV-1-seropositive women, their spouses and their newly born children during 36 months of follow-up in Kinshasa, Zaïre.

OBJECTIVE: To calculate 3-year mortality rates in HIV-1-seropositive and HIV-1-seronegative mothers, their newborn children and the fathers of these children. DESIGN: Longitudinal cohort study of HIV-1-seropositive, age and parity-matched HIV-1-seronegative pregnant women, their newborn babies and the fathers of these children. SETTING: Obstetric ward and follow-up clinic at a large municipal hospital in Kinshasa, Zaïre. PARTICIPANTS: A total of 335 newborn children and their 327 HIV-1-seropositive mothers and 341 newborn children and their 337 HIV-1-seronegative mothers and the fathers of these children. MAIN OUTCOME MEASURES: Rates of vertical HIV-1 transmission and maternal, paternal and early childhood mortality. RESULTS: The lower and upper bounds of vertical transmission were 27 and 50%, respectively. The 3-year mortality rate was 44% in children with vertically acquired HIV-1 infection, 25% in children with HIV-1-seropositive mothers and indeterminant HIV-1 infection status, and 6% in uninfected children with HIV-1-seronegative mothers. HIV-1-seropositive women who transmitted HIV-1 infection to their most recently born child had lost a greater number of previously born children (mean, 1.5 versus 0.5; P < 0.05), were more likely to have had AIDS at delivery (25 versus 12%; P < 0.01) and were more likely to die during follow-up (22 versus 9%; P < 0.01) than HIV-1-seropositive women who did not transmit HIV-1 infection to their newborn child. Twenty-five out of 239 (10.4%) fathers of children with HIV-1-seropositive mothers, not lost to follow-up, died compared with three out of 310 (1%) fathers of children with HIV-1-seronegative mothers (P < 0.01). CONCLUSIONS: Families in Kinshasa, Zaïre, in which the mother was HIV-1-seropositive experienced a five to 10-fold higher maternal, paternal and early childhood mortality rate than families in which the mother was HIV-1-seronegative.

AIDS orphans in Kinshasa, Zaïre: incidence and socioeconomic consequences.

OBJECTIVE: To determine the incidence, morbidity, mortality, and socioeconomic consequences of becoming an AIDS orphan (a child with an HIV-1-seropositive mother who has died) in Kinshasa, Zaïre. DESIGN: A longitudinal cohort study was undertaken between 1986 and 1990. Within this cohort, a nested case-control study of AIDS orphans was performed. AIDS orphan cases were children with an HIV-1-seropositive mother who had died. Two groups of control children were identified. The first group of control children were age-matched children with HIV-1-seropositive mothers who were alive at the time of death of the AIDS orphan case mother. The second group of control children were children with HIV-1-seronegative mothers who were also alive at the time of death of the AIDS orphan case mother. SETTING: Obstetric ward and follow-up clinic at two large municipal hospitals in Kinshasa, Zaïre. PARTICIPANTS: A total of 466 HIV-1-seropositive women, their children, and the fathers of these children; 606 HIV-1-seronegative women, their children, and the fathers of these children. MAIN OUTCOME MEASURES: AIDS orphan incidence, HIV-1 vertical transmission rate, morbidity, mortality and socioeconomic indicators of the consequences of becoming an AIDS orphan. RESULTS: The AIDS orphan incidence rate was 8.2 per 100 HIV-1-seropositive women-years of follow-up. Vertical transmission of HIV-1 was higher in AIDS orphan cases (41%) than in control children with HIV-1-seropositive mothers (26%; P < 0.05). Among children without vertically acquired HIV-1 infection, morbidity rates and indices of social and economic well-being were similar in AIDS orphans and control children. Five out of 26 (19%) AIDS orphan cases died during follow-up, compared with three out of 52 (6%) control children (P < 0.05). CONCLUSION: During a 3-year follow-up period, children with HIV-1-seropositive mothers had a considerable risk of becoming an AIDS orphan. However, the presence of a concerned extended family appeared to minimize any adverse health and socioeconomic effects experienced by orphan children.

Prevention of perinatal HIV transmission: are there alternatives to pre-pregnancy serological screening in Kinshasa, Zaire?

Complete obstetrical and medical histories were obtained from 6312 women between the ages of 15 and 45 years who had undergone HIV serological tests. Individual factors were examined for sensitivity, specificity and positive predictive value of HIV infection. No individual risk factors for HIV infection were identified which had sensitivities greater than 60%. Combinations of factors were modelled by logistic regression. Only a model which included indicators of present illness with AIDS/HIV-related symptoms (i.e., chronic fever, diarrhea or profound weight loss) was predictive of HIV serostatus. These results suggest that identification of healthy women at high risk of HIV infection using non-serological information is not feasible. Thus, since the yearly cost of universal serological screening is prohibitively expensive in the Zairean context, HIV/AIDS education and prevention campaigns may in fact be a more cost-effective means of preventing perinatal transmission of HIV.

PIP: Complete obstetrical and medical histories were obtained from 6312 women between ages 15-45 who had undergone HIV serological tests. Individual factors were examined for sensitivity, specificity, and positive predictive value of HIV infection. No individual risk factors for HIV infection were identified which had sensitivities 60%. Combinations of factors were modelled by logistic regression. Only a model which included indicators of present illness with AIDS/HIV-related symptoms (chronic fever, diarrhea, or profound weight loss) was predictive of HIV serostatus. These results suggest that identification of healthy women at high risk of HIV infection using nonserological information is not feasible. Thus, since the yearly cost of universal serological screening is prohibitively expensive in Zaire, HIV/AIDS education and prevention campaigns may be a more cost-effective means of preventing perinatal HIV transmission.

High HIV-1 incidence in young women masked by stable overall seroprevalence among childbearing women in Kinshasa, Zaïre: estimating incidence from serial seroprevalence data.

OBJECTIVE: To describe the dynamics of the HIV-1 epidemic in childbearing women in Kinshasa, Zaïre, by estimating incidence from serial seroprevalence studies. METHODS: In 1986 and 1989, 5937 and 4623 pregnant women, respectively, were screened for HIV-1 in Kinshasa. We estimated age-specific incidence from two seroprevalence surveys by using a birth-year cohort analysis and adjusting for differences in mortality and fertility between HIV-1-infected and uninfected women. Mortality and fertility data were measured in a cohort of women recruited from the survey in 1986 and followed until 1989. RESULTS: While the overall HIV-1 seroprevalence changed little (5.8% in 1986 and 6.5% in 1989; P = 0.17), the prevalence increased in birth-year cohorts of women under 25 years of age in 1989 from 3.2 to 6.2% (P < 0.001), but decreased for women above 25 years of age from 6.9 to 6.7% (P = 0.7). In addition, new HIV infections between 1986 and 1989 were balanced by a higher mortality and lower fertility observed in HIV-infected women. After adjusting for these effects, we estimated an overall 3-year cumulative HIV-1 incidence of 2.8 per 100 uninfected women [95% confidence interval (CI), 1.4-4.2]. The highest incidence, 5.7 per 100 (95% CI, 3.5-8.0), was in women aged 20-24 years in 1989. CONCLUSION: Despite an overall relatively stable HIV-1 prevalence in childbearing women in Kinshasa between 1986 and 1989, approximately 40% of all HIV-1 infections detected in the 1989 survey occurred between 1986 and 1989, and 60% occurred in women under 25 years of age in 1989.

Impact of HIV counseling and testing among child-bearing women in Kinshasa, Zaïre.

OBJECTIVE: To determine the impact of HIV counseling and testing among child-bearing women. STUDY SETTING: Mama Yemo Hospital in Kinshasa, Zaïre. PARTICIPANTS AND INTERVENTIONS: After informed consent, 187 HIV-seropositive and 177 HIV-seronegative child-bearing women received pre- and post-test counseling for HIV infection. MAIN OUTCOME MEASURES: Participant knowledge of HIV/AIDS and plans for notifying partners of serologic status and contraceptive use at the time of counseling, and actual partner involvement and contraception use 12 months later. RESULTS: During pre-test counseling, participant knowledge of HIV infection was high, although 30% of women were unaware of perinatal HIV transmission, and 50% did not know that HIV infection could be asymptomatic. At post-test counseling, 70% of mothers (47% of HIV-seropositive, 94% of HIV-seronegative) intended to notify their partners and have joint counseling and testing, although after 12 months, only 2.2% of all women and 7.9% of those who desired assistance to notify their partner returned with their partners for joint counseling and testing. Similarly, 86% planned to use birth control (61% condoms), with HIV-seropositive women more likely to prefer condoms than HIV-seronegative women (71 versus 53%; P < 0.001). After 12-months, however, only 20% of HIV-seropositive women reported condom use, and the frequency of pregnancy in both groups was approximately equal. CONCLUSIONS: HIV counseling and testing led to higher rates of contraceptive and condom use, although the actual level was lower than the intended use. To further reduce the risk of heterosexual and perinatal HIV transmission in families with an HIV-infected woman, counseling should also include their male partners.

Evidence from Zaire that breast-feeding by HIV-1-seropositive mothers is not a major route for perinatal HIV-1 transmission but does decrease morbidity.

Breast-feeding as a route of HIV-1 transmission during infancy but also as a protective measure against early childhood morbidity has been investigated prospectively in children born to HIV-1-seropositive mothers and control children born to age- and parity-matched HIV-1-seronegative women. The mothers of all study children had been enrolled antenatally at a maternity hospital in Kinshasa, Zaire, which served a relatively affluent group of women who sometimes chose not to breast-feed their infants. In 106 children born to HIV-1-seropositive women, the rate of HIV-1 transmission was 21% in 28 infants exclusively breast-fed, 19% in 68 infants both breast- and bottle-fed and 0% in 10 infants who were bottle-fed only (P = 0.35). In contrast, non-HIV-1-infected children of both HIV-1-seropositive and HIV-1-seronegative mothers who were exclusively breast-fed compared with uninfected children who were not exclusively breast-fed had significantly lower incidence rates of acute diarrhea, fever and lower respiratory tract infection. The lack of a dose-response effect between breast-feeding and perinatal HIV-1 transmission and the presence of a protective effect of breast-feeding against common causes of early childhood morbidity and mortality support the current World Health Organization recommendation that breast-feeding should continue to be promoted in all developing countries, including those with high HIV-1 prevalence rates in women of childbearing age.

Fertility rates in 238 HIV-1-seropositive women in Zaire followed for 3 years post-partum.

Birth-control use and fertility rates were prospectively determined in 238 HIV-1-seropositive and 315 HIV-1-seronegative women in Kinshasa, Zaire, during the 36-month period following the delivery of their last live-born child. No women delivered children during the first follow-up year. Birth-control utilization rates (percentage use during total observation time) and fertility rates (annual number of live births per 1000 women of child-bearing age) in the second year of follow-up were 19% (107.4 per 1000) for HIV-1-seropositive women and 16% (144.7 per 1000) for HIV-1-seronegative women. In the third year of follow-up these rates were 26 (271.0 per 1000) and 16% (38.6 per 1000) for HIV-1-seropositive and HIV-1-seronegative women, respectively (P less than 0.05 for the difference in birth-control utilization and fertility rates between seropositive and seronegative women in the third year of follow-up). Seven (2.9%) of the 238 HIV-1-seropositive women initially included in the study brought their sex partners in for HIV-1 testing; three (43%) of these men were found to be HIV-1-seropositive. New HIV-1 infection did not have a dramatic effect on the fertility of seropositive women. The nearly uniform unwillingness of HIV-1-seropositive women to inform husbands or sexual partners of their HIV-1 serostatus accounted in large part for the disappointingly high fertility rates in seropositive women who had been provided with a comprehensive program of HIV counseling and birth control. Counseling services for seropositive women of child-bearing age which do not also include these women's sexual partners are unlikely to have an important impact on their high fertility rates.

Evidence of marked sexual behavior change associated with low HIV-1 seroconversion in 149 married couples with discordant HIV-1 serostatus: experience at an HIV counselling center in Zaire.

To determine the effect of an HIV-1 counselling program on 149 married Zairian couples with discordant HIV-1 serology, the rates of HIV-1 seroconversion and reported condom utilization have been observed during 382.4 person-years of follow-up (minimum follow-up time per couple of 6 months). Before determination of HIV-1 serostatus and counselling, less than 5% of these couples had ever used a condom. One month after notification of HIV-1 serostatus and counselling, 70.7% of couples reported using condoms during all episodes of sexual intercourse. At 18 months follow-up, 77.4% of the 140 couples still being followed reported continued use of condoms during all episodes of sexual intercourse. At the time of notification of HIV-1 serostatus, 18 couples experienced acute psychological distress. Home-based counselling by trained nurses resolved these difficulties in all but three couples who subsequently divorced. Intensive counselling following notification of HIV-1 serostatus led to low rates of HIV-1 seroconversion (3.1% per 100 person-years of observation) in Zairian married couples with discordant HIV-1 serostatus who voluntarily attended an HIV counselling center.

Evaluation of the WHO clinical case definition for AIDS in rural Zaire.

The clinical case definition for AIDS proposed by WHO for use in Africa was evaluated against HIV antibody status in 72 patients in rural Zaire. Twenty-one (29%) of the patients were antibody-positive. For diagnosing anti-HIV seropositivity, the case definition had a sensitivity of 52%, a specificity of 78%, a positive predictive value of 50% and a negative predictive value of 80%. Calculation of the positive predictive value at different levels of prevalence of HIV infection suggests that the case definition operates at maximum reliability in selected high-risk groups. Modifications to the case definition should be evaluated to try and improve its sensitivity and positive predictive value.

PIP: In many areas of Africa where AIDS is endemic, facilities for laboratory diagnosis are too limited to reliably diagnose opportunistic infections. Therefore, the World Health Organization defined a clinical case definition of AIDS in which 2 major signs and at least 1 minor sign must be present to diagnose AIDS. The major signs are: weight loss greater than 10%, diarrhea for more than 1 month, and prolonged fever for more than 1 month. The minor signs are: persistent cough for more than 1 month, generalized pruritic dermatitis, recurrent herpes zoster, oropharyngeal candidiasis, chronic disseminated herpes simplex, and generalized lymphadenopathy. (The presence of Kaposi's sarcoma or cryptococcal meningitis are sufficient by themselves for a diagnosis of AIDS.) 72 patients in 4 hospitals in Equateur Province of Zaire were used to test the reliability of the clinical case definition. 21 (29%) of the patients were HIV seropositive, and 22 (32%) fulfilled the clinical criteria. From these data the sensitivity of the case definition was 52%, specificity was 78%, positive predictive value was 50%, and negative predictive value was 80%. Since positive predictive value rises with prevalence and HIV infection is maximal in the 20-40 age group, restricting the case definition to this age group would increase its predictive value. Exclusion of patients with tuberculosis would reduce the number of false positive results.

Prevention of transfusion-associated HIV transmission in Kinshasa, Zaire: HIV screening is not enough.

The purpose of this study was to develop a strategy to reduce transfusion-related HIV transmission which went beyond the limits of routine HIV screening of blood donors. Current blood transfusion practices were assessed in 1044 patients for whom staff physicians had requested a transfusion between 5 September and 19 October, 1988. Children under 5 years of age with malaria, and pregnant women with acute anaemia requiring blood transfusion were the two highest risk groups. Many of the transfusions were given without an obvious medical indication; 22.7% (214 out of 955) of the recipients were transfused without prior laboratory tests [haemoglobin (Hb) or haematocrit (Hct)], 7.2% with Hb greater than 6g/100ml or Hct greater than 25% and 16.6% without clinical signs of severe anaemia (pulse less than 100/min without shortness of breath). The data of this study were used to organize a workshop for all the physicians responsible for blood transfusions in Kinshasa and two nearby health zones. A consensus statement on the indications for blood transfusion was developed. Subsequently, transfusion centres adopted this consensus statement instead of previous guidelines.

Heterosexual transmission of HIV-1 among employees and their spouses at two large businesses in Zaire.

To better understand the reasons why up to 80% of all HIV-1 infections in Zaire, but less than 5% in North America and Europe, are acquired through heterosexual transmission, and to assess the impact of HIV-1 infection on a large urban African workforce, we enrolled 7068 male employees, 416 female employees and 4548 female spouses of employees at two large Kinshasa businesses (a textile factory and a commercial bank) in a prospective study of HIV-1 infection. The HIV-1 seroprevalence rate was higher in male employees (5.8%) and their spouses (5.7%) at the bank than among male employees (2.8%) and their spouses (3.3%) at the textile factory. At both businesses HIV-1 seroprevalence was higher among employees in managerial positions (5.0%) than among workers in lower-level positions (3.0%; P less than 0.0001). In a multivariate analysis of male employees, receipt of a transfusion, a history of genital ulcer disease, working at the bank, urethritis, or being divorced or separated were independently associated with HIV-1 infection. During 1987 and 1988, AIDS was the most common cause of death among recently employed workers, accounting for 20 and 24% of all deaths at the textile factory and the commercial bank, respectively. The HIV-1 seroprevalence rate was higher among female workers (7.7%) than among the spouses of male workers (3.9%; P = 0.001). In multivariate analysis of the wives of workers, having an HIV-1-seropositive spouse, receipt of a blood transfusion, or a history of genital ulcer disease were independently associated with HIV-1 infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Successful use of pooled sera to determine HIV-1 seroprevalence in Zaire with development of cost-efficiency models.

To determine the accuracy and cost efficiency of pooling sera prior to HIV-1 testing, sera from 8,000 Kinshasa factory workers and their spouses were screened individually (2.44% seropositive) and in 800 pools of 10 sera each. There were no false-negative or false-positive pools, resulting in a calculated seroprevalence estimate of 2.42%. Further testing of all sera in positive pools can identify HIV-positive individuals. These applications were modeled to compare the cost-efficiency of pooling with individual testing under different conditions. The results suggest that pooling provides an alternative test format for use in both developing and industrialized countries when the seroprevalence and/or the marginal cost of obtaining a sample are sufficiently low. For our cohort, testing only the pools for seroprevalence estimation resulted in a 78% cost saving compared with individual testing; pooling with subsequent identification of individual seropositives represented a 56% cost reduction.

Epidemiology of HIV infection in Africa.

HIV infection in Africa is primarily acquired through heterosexual activity, accounting for up to 80% of cases. Prostitutes and sexually promiscuous individuals are at particularly high risk of acquiring infection via this route. In the general population, women between the ages of 18 and 30 years are at increased risk of transmission. The role of cofactors, particularly concurrent sexually transmitted diseases (STDs), appears to facilitate heterosexual spread. These groups represent opportunities for targeted prevention programs aimed at education, increased condom use, prompt treatment of STDs, and reduction in the number of sexual partners. HIV infection acquired via blood transfusion may account for up to 10% of new cases of HIV infection. Children with malaria and nutritionally induced anemias are at special risk of acquiring infection by this route. Early treatment of malaria, surveillance for and treatment of malnutrition, adoption of rigorous criteria for blood transfusion, and implementation of machine-independent, low cost HIV screening programs in transfusion centers will help prevent these infections. As the epidemiology of HIV infection becomes better understood, other opportunities for technologically appropriate, cost-effective interventions will become available and will facilitate African HIV control and prevention programs.

Diagnosis of HIV infection with instrument-free assays as an alternative to the ELISA and western blot testing strategy: an evaluation in Central Africa.

The efficiency of an alternative instrument-free testing strategy was evaluated using a membrane-based rapid screening assay (HIVCHEK and its new version HIVCHEK1 + 2) in serial combination with a particle agglutination assay (SERODIA-HIV). Among 1,054 Zairian individuals at high risk of HIV infection, 573 were Western blot-positive for HIV-1 (54.4%) and none were Western blot-positive for HIV-2. In this group, the sensitivities of the serial combination HIVCHEK plus SERODIA-HIV and HIVCHEK1 + 2 plus SERODIA-HIV were 98.1 and 98.2%, respectively, and the specificities were 99.6 and 99.5% compared with HIV-1 Western blot. The positive predictive values were 99.6% for HIVCHEK plus SERODIA-HIV and 99.5% for HIVCHEK1 + 2 plus SERODIA-HIV; the negative predictive values were 97.8 and 97.9%, respectively. Among 1,495 pregnant women, 90 were Western blot-positive for HIV-1 (6.0%), and 54 of 1,510 blood donors were HIV-1 Western blot-positive (3.6%). None were positive for HIV-2. The sensitivities of HIVCHEK plus SERODIA-HIV and HIVCHEK1 + 2 plus SERODIA-HIV in these groups were 98.6 and 99.3%, respectively, and the specificities were 99.8 and 99.7%. The positive and negative predictive values of HIVCHEK plus SERODIA-HIV were 96.6 and 99.9%, respectively, and they were 94.1 and 99.9%, respectively, for HIVCHEK1 + 2 plus SERODIA-HIV. These instrument-free testing strategies are efficient alternatives for serodiagnosis of HIV-1 infection, although their cost should be further reduced.

Detection of salivary HIV-1-specific IgG antibodies in high-risk populations in Zaire.

Saliva and blood samples were tested for human immunodeficiency virus-1 (HIV-1) antibodies in two high-risk populations in Kinshasa, Zaire. In a seroprevalence study of 458 sexually transmitted disease (STD) clinic attendees, 142 of 145 seropositive individuals had enzyme-linked immunosorbent assay (ELISA)-positive saliva samples (97.9% sensitivity). All saliva samples from seronegative patients were ELISA-negative (100% specificity). Of the 142 ELISA-positive saliva specimens, 137 were also Western blot-positive (94.5% sensitivity). In a subsequent seroincidence study of 315 initially seronegative female prostitutes followed during 183 woman-years of observation, 9 of 14 women who seroconverted (7.7% seroincidence) had ELISA-positive saliva samples at the time seroconversion was detected. Only three of these saliva specimens could be confirmed by Western blot. Although salivary testing for HIV-1 antibodies using conventional assays was not sensitive in detecting recent seroconversions, screening of salivary samples for HIV-1 antibody provides a convenient alternative method for conducting seroprevalence surveys in populations in whom venipuncture is not possible or convenient.