Impact of enhanced notification of tuberculosis laboratory results to minimise treatment delay, Chiang Rai Hospital, Northern Thailand.

SETTING: A provincial referral hospital in northern Thailand, where a cross-sectional study from 1995-1996 reported on the occupational risk of Mycobacterium tuberculosis transmission. OBJECTIVE: To assess the impact of acid-fast bacilli sputum smear-positive results notification to improve tuberculosis (TB) services by documenting the location of sputum collection, completing the TB register immediately, and minimising delays between hospital admission and treatment initiation. DESIGN: The cohort of smear-positive TB patients identified through laboratory microscopy record reviews from 1994-1999. Time from admission to hospital, laboratory diagnosis of TB, registration for treatment, and initiation of therapy were determined during the implementation of enhancing the laboratory results notification system. RESULTS: The number of unregistered TB patients fell from 44 cases in 1994 to none in 1999. The time elapsed from admission to treatment initiation decreased from a mean of 5.6 days in 1997 (n = 162) to 3.1 days in 1999 (n = 136) (P < 0.001). This decrease was attributed to a reduction in time between laboratory diagnosis and treatment from 2.7 days in 1997 to 0.6 days in 1999 (P < 0.001). CONCLUSION: Prompt identification, isolation and treatment of TB patients occurred through an enhanced laboratory notification system. Such systems are inexpensive, improve TB care services and may reduce nosocomial transmission of M. tuberculosis.

Risk of Mycobacterium tuberculosis infection and disease among health care workers, Chiang Rai, Thailand.

SETTING: A provincial referral hospital in northern Thailand, where a cross-sectional study during 1995-1996 reported on the occupational risk of Mycobacterium tuberculosis transmission. OBJECTIVE: To describe the effectiveness of prevention strategies for nosocomial tuberculosis (TB). DESIGN: A prospective study among health care workers (HCW) including annual tuberculin skin test (TST) screening and active TB surveillance. Following a comprehensive risk assessment, preventive interventions were implemented targeting HCWs, hospitalised patients, and the hospital environment. RESULTS: The number of pulmonary TB cases diagnosed increased steadily from 102 in 1990 to 356 in 1999. The TST conversion rate was 9.3 (95% CI 3.3-15) per 100 person-years (py) in 1995-1997, but declined steadily to 2.2 (95% CI 0.0-5.1) in 1999. HCWs first screened within 12 months of employment had higher TST conversion rates (adjusted RR = 9.5, 95% CI 1.8-49.5) compared to those employed for longer than 12 months. The annual rate of active TB per 100 000 HCWs was 536 in 1995-1999. CONCLUSION: These HCWs were exposed to active TB patients and were at risk for M. tuberculosis infection, particularly during their first 12 months of employment. Implementation of nosocomial TB control measures in 1996 was followed by declining TST conversion rates, despite increasing exposure to active TB patients.

Leaving sex work: barriers, facilitating factors and consequences for female sex workers in northern Thailand.

Factors facilitating or inhibiting women's ability to leave sex work are still poorly characterized, and little is known about women's lives after they leave the profession. This paper presents findings from a qualitative study about factors affecting women's ability to leave sex work and influencing their lives after leaving. We interviewed 42 current and former female sex workers (FSWs) drawn from a cohort study of 500 FSWs in northern Thailand. All but one of the participants had quit sex work at least once. The majority experienced one or more quit-re-entry-quit cycles. Women's ability and decisions to leave sex work were determined primarily by four factors: economic situation, relationship with a steady partner, attitudes towards sex work and HIV/AIDS experience. Economic concerns, ranging from survival needs to materialistic desires, had the strongest influence. Most women perceived their risk for HIV infection to be lower after leaving sex work, but three of the 17 HIV-infected women acquired infection after having left, presumably from their steady partners. Prevention efforts should guide women as they transition out of commercial sex work. Interventions aimed at assisting women wanting to leave sex work need to address the role of economic factors.

Women's willingness to participate in microbicide trials in Northern Thailand.

To assess women's interests and concerns regarding participation in trials of microbicides in Chiang Rai, Thailand, we administered structured questionnaires. Before answering the questionnaire, women attended an educational session on microbicides and clinical trials. Of 370 participants, 82% correctly answered 8 or more of the 11 overall comprehension questions, indicating an adequate knowledge base among the women from which to answer questions about attitudes toward microbicide trials. The most common motivations for participating in a trial were "getting tested for HIV" and "doing something good for women's health." The greatest barrier to participation was women's fear that if they proposed use of a microbicide, their husbands might feel protected and thereby have more sex partners. Overall, 6.2% said they would be "definitely willing to participate," and 66.8% said they wanted to participate but wanted to think about it. Most women previously unacquainted with the concept of microbicides or clinical trial design displayed adequate knowledge of these subjects after the short educational session. If women's initial reactions are validated by actual willingness, surveys could prove valuable for selecting sites for microbicide trials, estimating enrollment rates, and tailoring trials to make them most acceptable to women.

Rapid assessment of sexual behavior, drug use, human immunodeficiency virus, and sexually transmitted diseases in northern thai youth using audio-computer-assisted self-interviewing and noninvasive specimen collection.

BACKGROUND: Drug use, unwanted pregnancy, human immunodeficiency virus (HIV) infection, and sexually transmitted diseases are serious health problems among Thai youth. The gravity of these problems demands high-quality data to direct public health policy and prevention programs. Previous studies of stigmatized behaviors have been hampered by participation bias and underreporting. To evaluate sexual behavior, disease, and drug use, we used audio-computer-assisted self-interviewing (ACASI) and noninvasive specimen collection methods. We also evaluated effectiveness of these methods in minimizing participation bias and underreporting. METHODS: In late 1999, students aged 15 to 21 years attending 3 vocational schools were invited to participate in a cross-sectional survey. Consenting students completed a classroom-based ACASI interview using a confidential code number system. Oral fluid specimens were tested for HIV antibodies, and urine was tested for chlamydial and gonococcal nucleic acids, methamphetamines, and opiates. RESULTS: Of 1736 invited students, 1725 (99%) agreed to participate. Of these, 48% of the male students and 43% of the female students reported ever having had sexual intercourse. Overall, the mean number of lifetime sexual partners was 4.6 among male participants (median: 2) and 2.8 among female participants (median: 1). Consistent use of condoms with steady partners was reported by 16% of male participants and 11% of female participants who had such partners. Of all male participants, 7% had ever paid for sex, 3% had ever sold sex, and 7% had ever been coerced to have sex. Of all female participants, 3% had ever sold sex and 21% had ever been coerced to have sex. Among women with a history of sexual intercourse, 27% reported at least 1 pregnancy. Of these pregnancies, 83% were terminated. Among those with sexual intercourse experience, the prevalence of HIV infection was 0.5%; of infection with Neisseria gonorrhoeae, 0.4%; and of infection with Chlamydia trachomatis, 5%. Twenty-nine percent of students reported ever having used methamphetamines. Ten percent had a methamphetamine-positive urine test. In the ACASI interview, 16% of these denied ever having used methamphetamines. The prevalence of opiate positive urine tests was low (0.2%). CONCLUSION: This study shows that adolescents and young adults in Chiang Rai are at high risk for having unprotected intercourse, being coerced to have sex, unwanted pregnancy, sexually transmitted diseases, and drug use. The high enrollment rate demonstrates the feasibility and acceptability of using ACASI and noninvasive specimen collection methods in a developing country. ACASI use may lead to increased, but not to complete, self-reporting of sensitive behaviors.

An HLA-directed molecular and bioinformatics approach identifies new HLA-A11 HIV-1 subtype E cytotoxic T lymphocyte epitopes in HIV-1-infected Thais.

Only limited cytotoxic T lymphocyte (CTL) epitope mapping has been done in nonsubtype B HIV-infected persons. We used molecular immunogenetic tools to determine HIV-specific CTL responses in HIV-1 Env subtype E-infected female sex workers (FSWs) from northern Thailand, where more than 50% of the population is HLA-A11 positive. EpiMatrix, a computer-based T cell epitope prediction algorithm, and a manual editing approach were used to predict 77 possible HLA-A11 CTL epitopes in HIV-1, some of which were conserved between subtypes B and E. MHC binding of these peptides was determined in an HLA-A11 stabilization assay, and binding peptides were tested for CTL recognition in eight HLA-A11-positive FSWs. Subtype E versions of known HLA-A2 subtype B HIV epitopes were also tested in four HLA-A2 positive FSWs. CTL responses were detected in all HLA-A11-positive and in three of four HLA-A2-positive persons. Among the 12 FSWs responses to peptides were found to Pol in 9 (75%), Env in 7 (58%), Nef in 5 (42%), and Gag in 5 (42%), and to conserved epitopes in 8 (67%). To identify HLA-A11 CTL epitopes in the absence of prediction tools, it would have been necessary to test almost 3000 10-mer peptides. EpiMatrix and manual predictions reduced this number to 77, of which 26 were MHC binding and 12 were CTL epitopes. Six of these HLA-A11 CTL epitopes have not been previously reported and are located in RT, gp120, and gp41. This report of CTL responses in subtype E-infected individuals defines epitopes that may be useful in HIV pathogenesis or vaccine studies.

HIV-specific cytotoxic T lymphocytes, HLA-A11, and chemokine-related factors may act synergistically to determine HIV resistance in CCR5 delta32-negative female sex workers in Chiang Rai, northern Thailand.

Understanding how highly HIV-exposed individuals remain HIV uninfected may be useful for HIV vaccine design and development of new HIV prevention strategies. To elucidate mechanisms associated with resistance to HIV infection, immunologic and genetic factors were examined in 14 HIV-exposed but persistently seronegative (HEPS) female sex workers from Chiang Rai, northern Thailand and in ethnically matched, HIV-positive (n = 9) and HIV-negative women (n = 9). The HEPS women were identified in a study of commercial sex workers who had an HIV-1 incidence of 20.3 per 100 person-years. A high frequency of HLA-A11 was observed in HEPS women (86%) compared with northern Thai controls (56%). HIV-specific cytotoxic T lymphocyte (CTL) lytic responses were detected in cryopreserved peripheral blood mononuclear cells (PBMCs), using HLA-A-matched subtype E HIV-1 peptides in four of seven (57%) HEPS women, eight of eight HIV-positive women, and zero of nine HIV-negative unexposed controls (p = 0.019 HEPS women vs. HIV-negative controls). CTL lysis levels were low, but responses were detected to peptides from Nef, Pol, Gag, and Env. Nef responses predominated in HEPS women. Compared with controls, HEPS women tended to have higher frequencies of CCR5 promotor 59402GG and SDF-1 3'UTR 801A genotypes known to influence HIV transmission or course of disease. HEPS women also had higher levels of spontaneous RANTES production by PBMCs than other groups. Each of these factors could potentially contribute to HIV resistance. As most HEPS women had one or more of these factors, they may prevent HIV infection synergistically by blocking HIV cell entry, delaying its dissemination, or killing HIV-infected cells.

Production of a novel viral suppressive activity associated with resistance to infection among female sex workers exposed to HIV type 1.

To investigate mechanisms of natural resistance to human immunodeficiency virus type 1 (HIV-1), we obtained blood samples from eight women who remained HIV-1 negative after > 3 years of high-risk sex work in Chiang Rai, Thailand. CD4+ T lymphocytes from these highly exposed, persistently seronegative (HEPS) women were readily infectable in vitro with HIV-1 subtypes B and E. Autologous CD8+ cell suppression of both HIV-1 subtypes was evident in HEPS infection cultures, but to an extent also observed in cultures from non-HIV-exposed individuals. Furthermore, production of beta-chemokines was not enhanced in HEPS cultures. However, HEPS cultures displayed significantly enhanced production of a soluble activity that suppressed postintegrated HIV-1 replication. This activity was the unique product of CD4+ T cell and monocyte cocultures. Therefore, although HEPS individuals are apparently susceptible to infection, the production of a postintegrated HIV-1 suppressive activity during monocyte-T cell interactions might protect against the establishment of infection by limiting viral dissemination.

Viral load differences in early infection with two HIV-1 subtypes.

OBJECTIVES: Information on early HIV-1 infection has come primarily from studies of persons infected with subtype B in North America and Europe; much less is known about other subtypes. The purpose of the present study was to compare the virologic and immunologic parameters following seroconversion among recently-infected persons infected with either of two different HIV-1 subtypes. METHOD: A prospective cohort study was carried out at methadone treatment clinics administered by the Bangkok Metropolitan Administration, Thailand. A total of 130 HIV-1-infected seroconverters (103 with HIV-1 subtype E and 27 with subtype B) were included in the study. The main outcome measures were serial HIV-1 RNA viral load, natural killer cell percentage, CD4 and CD8 lymphocyte counts since seroconversion. RESULTS: The demographic and behavioral characteristics of persons with either subtype were similar. Median RNA viral levels at the earliest time within 3 months of seroconversion were more than three times higher for persons infected with subtype E than subtype B (63 100 versus 18 050 copies/ml, P = 0.001). However, this difference decreased over time such that viral loads were similar at 12, 18, and 24 months following seroconversion. The CD4 and CD8 lymphocyte counts were similar in infections with either subtype during the entire period up to 24 months post-seroconversion. CONCLUSIONS: Higher viral loads associated with subtype E may result from inter-subtype biological differences; however, the epidemiological dynamics of transmission in Bangkok may have also contributed to this phenomenon.

HIV seroconversion during pregnancy and risk for mother-to-infant transmission.

Pregnant women infected with HIV-1 were enrolled in a prospective mother-to-infant transmission study from 1992 through 1994 in Bangkok. In participating hospitals, voluntary HIV testing was routinely offered at the beginning of antenatal care and again in the middle of the third trimester of pregnancy. Women who seroconverted to HIV during pregnancy were compared with women who had tested positive on their first antenatal test. Maternal HIV RNA levels were determined during pregnancy, at delivery, and postpartum using RNA polymerase chain reaction (PCR), and infection status in infants was determined by DNA PCR. No infants were breast-fed, but prophylactic antiretroviral therapy was not yet used in Thailand to prevent transmission from mother to infant. Among enrolled women, 16 who seroconverted during pregnancy and 279 who were HIV-1-seropositive at their first antenatal test gave birth. Median plasma RNA levels at delivery were similar for the two groups (17,505 and 20,845 copies/ml, respectively; p =.8). Two (13.3%) of 15 infants born to women who seroconverted and 66 (24.8%) of 266 infants born to previously HIV-seropositive women were infected with HIV (p =.5). There was no increased risk for mother-to-infant HIV transmission and no significant difference in viral load at delivery between HIV-infected women who seroconverted to HIV during pregnancy and those who were HIV-seropositive when first tested.

Evaluation of a sensitive/less-sensitive testing algorithm using the 3A11-LS assay for detecting recent HIV seroconversion among individuals with HIV-1 subtype B or E infection in Thailand.

The development of a serologic algorithm to determine recent HIV seroconversion, using sensitive/less-sensitive testing strategies, has generated widespread interest in applying this approach to estimate HIV-1 incidence in various populations around the world. To evaluate this approach in non-B subtypes, longitudinal specimens (n = 522) collected from 90 incident infections among injecting drug users in Bangkok (subtype B infection, n = 18; subtype E infection, n = 72) were tested by the 3A11-LS assay. Standardized optical density (SOD) was calculated, using median values, and the window period between seroconversion as determined by sensitive and less sensitive tests was estimated by a maximum-likelihood model described previously. Our results show that the mean window period of the 3A11-LS assay was 155 days (95% CI, 128-189 days) for subtype B but was 270 days (95% CI, 187-349 days) for subtype E specimens from Thailand. About 4% of individuals with incident subtype E infections remained below the threshold (SOD of 0.75), even 2 years after seroconversion. Among the patients with clinical AIDS and declining antibodies, none of the 7 individuals with subtype B, but 10 (8.7%) of 115 with subtype E infections, were misclassified as recent infections. Lowering the cutoff to an SOD of 0.45 for subtype E specimens resulted in a mean window period of 185 days (95% CI, 154-211 days), with all individuals seroconverting, and reduced the number of subtype E-infected patients with AIDS who were misclassified as having recent infection to 2.6%. Our results demonstrate that the 3A11-LS assay has different performance characteristics in detecting recent infections among individuals infected with subtypes B or E. Determining appropriate cutoffs and mean window periods for other HIV-1 subtypes will be necessary before this approach can be reliably implemented in settings where non-B subtypes are common.

Evaluation of United States-licensed human immunodeficiency virus immunoassays for detection of group M viral variants.

Six Food and Drug Administration (FDA)-licensed human immunodeficiency virus type 1 (HIV-1) and HIV-1/2 immunoassays, including five enzyme immunoassays and one rapid test, were challenged with up to 250 serum samples collected from various global sites. The serum samples were from individuals known to be infected with variants of HIV-1 including group M subtypes A, B, B', C, D, E, F, and G and group O. All immunoassays detected the vast majority of samples tested. Three samples produced low signal over cutoff values in one or more tests: a clade B sample, an untypeable sample with a low antibody titer, and a group O sample. It is concluded that HIV-1 immunoassays used in the United States are capable of detecting most HIV-1 group M variants.

Continued high HIV-1 incidence in a vaccine trial preparatory cohort of injection drug users in Bangkok, Thailand.

BACKGROUND: A large epidemic of HIV-1 subtype B began among injection drug users (IDUs) in Bangkok in 1988. Despite ongoing prevention efforts, HIV-1 prevalence among IDUs remained at 30-50% through the 1990s. OBJECTIVES: To measure the incidence of HIV-1 infection and related risk factors to guide prevention efforts and to evaluate the feasibility of conducting an HIV vaccine efficacy trial. DESIGN AND METHODS: A prospective cohort study in which IDUs attending methadone treatment programs in Bangkok were screened during 1995-1996 for enrollment into the study. IDUs found to be HIV-seronegative on two occasions were offered enrollment with follow-up visits every 4 months. On each visit participants were evaluated with a questionnaire and serologic testing. RESULTS: A total of 1209 HIV-negative IDUs were enrolled. Through the end of 1998, the overall HIV-1 incidence rate was 5.8 (95% confidence interval, 4.8-6.8) per 100 person-years of follow-up. HIV-1 subtypes E and B accounted for 79 and 21% of infections, respectively. On multivariate analysis, HIV-1 seroconversion was primarily associated with the frequency of heroin injection, the sharing of injection equipment, and incarceration, especially with drug injection. Sexual behavior was not associated with increased risk for HIV-1. Risk factors for infection with HIV-1 subtypes E and B were similar. CONCLUSION: HIV-1 transmission risk remains high among Bangkok IDUs despite methadone treatment and other current prevention strategies. There is an urgent need to address this ongoing epidemic, especially in jails and prisons. This study led to the initiation in 1999 of a phase III HIV-1 vaccine efficacy trial in this population.

Safety of late in utero exposure to zidovudine in infants born to human immunodeficiency virus-infected mothers: Bangkok. Bangkok Collaborative Perinatal HIV Transmission Study Group.

BACKGROUND: Short-course zidovudine (ZDV) given in the late antenatal period can reduce mother-infant human immunodeficiency virus (HIV) transmission by one half. Because this intervention is being implemented in developing countries, evidence of its safety is needed. METHODS: In a randomized, double-blinded, placebo-controlled trial in Bangkok, HIV-infected pregnant women received either ZDV (300 mg twice daily from 36 weeks' gestation until labor, then every 3 hours until delivery) or an identical placebo regimen. Infants were evaluated at birth and at 1, 2, 4, 6, 9, 12, 15, and 18 months of age. Growth, clinical events, and hematologic and immunologic measurements were compared between treatment groups. RESULTS: Of the 395 children born (196 in ZDV group and 199 in placebo group), 330 were uninfected, 55 were infected, and 10 had indeterminate infection status. Overall, 319 children (81%) completed 18 months of follow-up, and 14 (4%) died before 18 months of age. Among uninfected children, the mean hematocrit was lower in the ZDV group at birth (49.1% vs 51.5%) but not at later ages; mean weight, height, head circumference, and CD4(+) and CD8(+) T lymphocyte counts were similar in both groups at all ages. Five uninfected children in the ZDV group but only one in the placebo group had a febrile convulsion. No other signs suggestive of mitochondrial dysfunction and no tumors were observed. Among infected children, an estimated 62% in the ZDV group and 77% in the placebo group survived free of Centers for Disease Control and Prevention class C disease during the 18-month follow-up. CONCLUSIONS: No significant adverse events were associated with short-course ZDV during 18 months of follow-up in this population.

Explosive spread and effective control of human immunodeficiency virus in northernmost Thailand: the epidemic in Chiang Rai province, 1988-99.

The human immunodeficiency virus type 1 (HIV-1) epidemic began in Asia later than most in other regions but then spread very rapidly. Upper northern Thailand was severely affected, with among the highest infection rates in Asia. The first 12 years of the HIV epidemic in Chiang Rai, Thailand's northernmost province are described. HIV infection was not reported in Chiang Rai until 1988 but, within a few years more than half of the brothel-based female sex workers and one in six of 21-year-old male Royal Thai Army conscripts from the province were HIV infected. Infection rates in Chiang Rai have since declined following an aggressive prevention campaign, but the number of AIDS cases continues to mount, along with profound demographic, social and economic effects.

HIV-1 seroprevalence, risk factors, and preventive behaviors among women in northern Thailand.

To study HIV-1 seroprevalence, risk factors, and preventive behaviors among reproductive-age women in northern Thailand, 804 consenting women who were identified postpartum or who were visiting family planning clinics were interviewed and tested during 1998 to 1999. Almost all women were currently married and had been pregnant more than once. Their median age was 27 years. HIV-1 seroprevalence was 3.1% overall and was higher in women aged between 25 and 29 years (5.9%), having had > or =2 lifetime sex partners (6.5%), or whose current marriage had lasted for < or =1 year (7.0%). No woman reported HIV risk factors other than heterosexual sex. Most (76%) HIV-infected women reported no casual sex partners and, therefore, had likely acquired the infection from their husbands. HIV testing and partner communications were common, but only 2% of couples used condoms consistently in the prior 6 months. Nearly half of these women perceived themselves at no or low risk for HIV infection; these women were less likely to have taken preventive actions. To prevent HIV transmission in stable partnerships in this population, additional efforts are needed to increase HIV testing and condom use, to improve women's negotiation skills, and to develop new methods that do not require partner cooperation such as vaginal microbicides or vaccines.

Placental abnormalities associated with human immunodeficiency virus type 1 infection and perinatal transmission in Bangkok, Thailand.

The effects of human immunodeficiency virus (HIV) type 1 on the placenta and the role of the placenta in mother-to-child HIV-1 transmission are not well understood. Placentas from 78 HIV-infected and 158 HIV-uninfected women were examined as part of a prospective perinatal HIV transmission study in Bangkok. HIV-infected women were more likely than HIV-uninfected women to have chorioamnionitis (odds ratio [OR], 2.1; P=.03), placental membrane inflammation (PMI; OR, 2. 7; P=.02), and deciduitis (OR, 2.3; P=.03) and less likely to have villitis (OR, 0.3; P=.02). However, among HIV-infected women, fewer women who transmitted infection to their child had chorioamnionitis (relative risk [RR], 0.2; P=.03), funisitis (RR, 0.4; P=.1), or PMI (RR undefined; P=.03). These findings suggest that, in this population, HIV-infected women are at increased risk for placental membrane inflammatory lesions, but that placental inflammatory lesions are not associated with increased perinatal HIV transmission.

A comparison of full-length glycoprotein 120 from incident HIV type 1 subtype E and B infections in Bangkok injecting drug users with prototype E and B strains that are components of a candidate vaccine.

Complete gp120 sequence information was obtained from eight persons with incident HIV-1 infections (four subtype E and four subtype B) who were part of a prospective injecting drug user (IDU) cohort in Bangkok, Thailand, during 1996-1998. The incident subtype E strains were similar to the prototype subtype E strain CM244 isolated in 1992 in northern Thailand. The incident subtype B strains displayed divergence, in both overall genetic distance and other significant gp120 characteristics, from the prototype North American subtype B strain HIV-MN. Recombinant gp120s derived from CM244 and HIV-MN strains are components of a vaccine that is undergoing phase III efficacy testing, begun in March 1999, among Bangkok area IDUs. The information presented here will be important in the evaluation of any breakthrough HIV-1 infections occurring among vaccinees during the vaccine trial and in ongoing vaccine development efforts in Thailand.

Early diagnosis of HIV-1-infected infants in Thailand using RNA and DNA PCR assays sensitive to non-B subtypes.

OBJECTIVES: To evaluate the sensitivity and specificity of RNA and DNA polymerase chain reaction (PCR) for early diagnosis of perinatal HIV-1 infection and to investigate early viral dynamics in infected infants. DESIGN: A cohort study of 395 non-breastfed infants born to HIV-infected mothers in a randomized clinical trial of short-course antenatal zidovudine. METHODS: Infant venous blood specimens collected at birth, 2 months, and 6 months of age were tested by qualitative DNA and quantitative RNA PCR (Roche Amplicor). To determine sensitivity and specificity of DNA and RNA PCR, results were compared with later DNA PCR results and to antibody results at 18 months. The HIV-1 subtype of the mother's infection was determined by peptide serotyping. RESULTS: In the study, 92% of mothers were infected with subtype E. DNA PCR sensitivity was 38% (20 of 53) at birth, and 100% at 2 months (53 of 53) and 6 months (47 of 47). RNA PCR sensitivity was 47% (25 of 53) at birth and 100% (53 of 53) at 2 months. All samples that tested DNA-positive tested RNA-positive. Specificity was 100% for both DNA and RNA testing at all timepoints. For infected infants, the median viral load of RNA-positive specimens was 407,000 copies/ml (5.6 log10) at birth, 3, 700,000 copies/ml (6.6 log10) at 2 months, and 1,700,000 copies/ml (6.2 log10) at 6 months. Infant RNA levels at 2 and 6 months did not differ by maternal zidovudine exposure, or RNA level at birth. CONCLUSION: This RNA PCR assay performed well for diagnosing perinatal HIV subtype E infection, detecting nearly half of infected infants at birth, and 100% at 2 and 6 months, with 100% specificity. Infected infant viral RNA levels were very high at 2 and 6 months, and were unaffected by maternal zidovudine treatment.