Male circumcision is associated with a lower prevalence of human papillomavirus-associated penile lesions among Kenyan men.

Human papillomavirus (HPV)-associated penile lesions in men may increase the risk of HPV transmission to their female partners. Risk factor data on HPV-associated penile lesions are needed from regions with a high burden of cervical cancer. Visual inspection of the penis was conducted using a colposcope at the 24-month visit among participants in a randomized controlled trial of male circumcision in Kenya, from May 2006 to October 2007. All photos were read independently by two observers for quality control. Penile exfoliated cells sampled from the glans/coronal sulcus and the shaft were tested for HPV DNA using GP5+/6+ PCR and for HPV16, 18 and 31 viral loads using a real time PCR assay. Of 275 men, 151 were circumcised and 124 uncircumcised. The median age was 22 years. Circumcised men had a lower prevalence of flat penile lesions (0.7%) versus uncircumcised (26.0%); adjusted odds ratio (OR) = 0.02; 95% confidence interval (CI) = 0.003-0.1. Compared to men who were HPV negative, men who were HPV DNA positive (OR = 6.5; 95% CI = 2.4-17.5) or who had high HPV16/18/31 viral load (OR = 5.2; 95% CI = 1.1-24.4) had higher odds of flat penile lesions. Among men with flat penile lesions, HPV56 (29.0%) and 16 (25.8%) were the most common types within single or multiple infections. Flat penile lesions are much more frequent in uncircumcised men and associated with higher prevalence of HPV and higher viral loads. This study suggests that circumcision reduces the prevalence of HPV-associated flat lesions and may ultimately reduce male-to-female HPV transmission.

Prevalence and risk factors of human papillomavirus infection by penile site in uncircumcised Kenyan men.

Human papillomavirus (HPV) prevalence was estimated from 2,705 sexually active, uncircumcised, human immunodeficiency virus seronegative men aged 17-28 years in Kisumu, Kenya. HPV prevalence was 51.1% (95% confidence interval: 49.2-53.0%) in penile cells from the glans/coronal sulcus and/or shaft. HPV prevalence varied by anatomical site, with 46.5% positivity in the glans/coronal sulcus compared with 19.1% in the shaft (p < 0.0001). High-risk HPV was detected in 31.2% of glans and 12.3% of shaft samples (p < 0.0001). HPV16 was the most common type and 29.2% of men were infected with more than one HPV type. Risk factors for HPV infection included presence of C. trachomatis, N. gonorrhea, self-reported sexually transmitted infections, and less frequent bathing. Lifetime number of sexual partners and herpes simplex virus type-2 seropositivity were also marginally associated with HPV infection.

Scaling sexual behavior or "sexual risk propensity" among men at risk for HIV in Kisumu, Kenya.

We present a scale to measure sexual risk behavior or "sexual risk propensity" to evaluate risk compensation among men engaged in a randomized clinical trial of male circumcision. This statistical approach can be used to represent each respondent's level of sexual risk behavior as the sum of his responses on multiple dichotomous and rating scale (i.e. ordinal) items. This summary "score" can be used to summarize information on many sexual behaviors or to evaluate changes in sexual behavior with respect to an intervention. Our 18 item scale demonstrated very good reliability (Cronbach's alpha of 0.87) and produced a logical, unidimensional continuum to represent sexual risk behavior. We found no evidence of differential item function at different time points (except for reporting a concurrent partners when comparing 6 and 12 month follow-up visits) or with respect to the language with which the instrument was administered. Further, we established criterion validity by demonstrating a statistically significant association between the risk scale and the acquisition of incident sexually transmitted infections (STIs) at the 6 month follow-up and HIV at the 12 month follow-up visits. This method has broad applicability to evaluate sexual risk behavior in the context of other HIV and STI prevention interventions (e.g. microbicide or vaccine trials), or in response to treatment provision (e.g., anti-retroviral therapy).

Herpes simplex virus type 2 antibody detection performance in Kisumu, Kenya, using the Herpeselect ELISA, Kalon ELISA, Western blot and inhibition testing.

BACKGROUND: In certain parts of Africa, type-specific herpes simplex virus type 2 (HSV-2) ELISAs may have limited specificity. To date, no study has been conducted to validate HerpeSelect and Kalon type-specific HSV-2 ELISAs using both the Western blot and recombinant gG ELISA inhibition testing as reference standards. METHODS: A total of 120 men who were HIV seronegative (aged 18-24 years) provided blood samples. HSV-2 IgG serum antibodies were detected using four different methods: HerpeSelect HSV-2 ELISA (n = 120), Kalon HSV-2 ELISA (n = 120), University of Washington Western blot (n = 101) and a recombinant inhibition test (n = 93). RESULTS: HSV-2 seroprevalence differed significantly by HSV-2 detection method, ranging from 24.8% with the Western blot to 69.8% with the HerpeSelect ELISA. Using the Western blot as the reference standard, the HerpesSelect had the highest sensitivity for HSV-2 antibody detection (100%) yet lowest specificity (40%). Similar results were obtained using the inhibition test as the reference standard. The sensitivity and specificity of the Kalon test versus the Western blot were 92% and 79%, respectively, and 80% and 82% versus the inhibition test. Using the inhibition test as the reference standard, the sensitivity of the Western blot appeared low (49%). CONCLUSIONS: In men in western Kenya who were HIV seronegative, the HerpeSelect and Kalon type-specific ELISAs had high sensitivities yet limited specificities using the Western blot as reference standard. Overall, the Kalon ELISA performed better than the HerpeSelect ELISA in these young men from Kisumu. Further understanding is needed for the interpretation of HSV-2 inhibition or ELISA test positive/ Western blot seronegative results. Before HSV-2 seropositivity may be reliably reported in selected areas of Africa, performance studies of HSV-2 serological assays in individual geographical areas are recommended.

Prospective study of correlates of vaginal Lactobacillus colonisation among high-risk HIV-1 seronegative women.

OBJECTIVE: Vaginal colonisation with Lactobacillus species is characteristic of normal vaginal ecology. The absence of vaginal lactobacilli, particularly hydrogen peroxide (H(2)O(2))-producing isolates, has been associated with symptomatic bacterial vaginosis (BV) and increased risk for HIV-1 acquisition. Identification of factors associated with vaginal Lactobacillus colonisation may suggest interventions to improve vaginal health. METHODS: We conducted a prospective cohort study of correlates of vaginal Lactobacillus colonisation among Kenyan HIV-1 seronegative female sex workers. At monthly follow-up visits, vaginal Lactobacillus cultures were obtained. Generalised estimating equations were used to examine demographic, behavioural and medical correlates of Lactobacillus isolation, including isolation of H(2)O(2)-producing strains. RESULTS: Lactobacillus cultures were obtained from 1020 women who completed a total of 8896 follow-up visits. Vaginal washing, typically with water alone or with soap and water, was associated with an approximately 40% decreased likelihood of Lactobacillus isolation, including isolation of H(2)O(2)-producing strains. Recent antibiotic use, excluding metronidazole and treatments for vaginal candidiasis, reduced Lactobacillus isolation by approximately 30%. H(2)O(2)-producing lactobacilli were significantly less common among women with Trichomonas vaginalis infection and those who were seropositive for herpes simplex virus type 2. In contrast, H(2)O(2)-producing lactobacilli were significantly more common among women with concurrent vaginal candidiasis. CONCLUSIONS: Modifiable biological and behavioural factors are associated with Lactobacillus colonisation in African women. Our results suggest intervention strategies to improve vaginal health in women at high risk for HIV-1.

A prospective study of risk factors for herpes simplex virus type 2 acquisition among high-risk HIV-1 seronegative women in Kenya.

OBJECTIVES: Several studies have demonstrated an association between herpes simplex virus type 2 (HSV-2) and HIV-1, but available data on risk factors for HSV-2 acquisition are limited. The objective of this analysis was to determine the incidence and risk factors for HSV-2 acquisition among HIV-1-seronegative female sex workers in Kenya. METHODS: Between February 1993 and December 2006, HIV-1-seronegative women attending a municipal sexually transmitted infection (STI) clinic were invited to enroll in a prospective cohort study. Screening for HIV-1 and STIs were done at monthly follow-up visits. Archived blood samples were tested for HSV-2. RESULTS: Of 1527 HIV-1-seronegative women enrolled, 302 (20%) were HSV-2 seronegative at baseline of whom 297 had at least one follow-up visit. HSV-2 incidence was high (23 cases/100 person-years; 115 cases). In multivariate analysis, HSV-2 was significantly associated with more recent entry into sex work, workplace and higher number of sex partners per week. Condom use was protective, although this was statistically significant only for the intermediate strata (25-75% condom use; HR 0.43; p = 0.05). There were statistical trends for bacterial vaginosis to increase HSV-2 risk (HR 1.56; p = 0.07) and for oral contraceptive use to decrease risk (HR 0.50; p = 0.08). The 23% annual HSV-2 incidence in this study is among the highest reported anywhere in the world. CONCLUSIONS: Women were at increased risk if they had recently entered sex work, had a higher number of sex partners or worked in bars. HSV-2 risk reduction interventions are urgently needed among high-risk African women.

Dermatophyte infections in primary school children in Kibera slums of Nairobi.

OBJECTIVE: To determine the prevalence and aetiology of dermatophyte infections in relation to social economic factors in primary school children in Kibera. DESIGN: A cross-sectional descriptive study. SETTING: City council sponsored schools namely Olympic, Kibera, Ayany and Mbagathi way all in Kibera, the largest of the informal settlement within Nairobi which is home to between 700,000-1,000,000 inhabitamts. The study was conducted between September 2006 and February 2007. SUBJECTS: A total of 422 primary school children from the ages of five years to 15 years were selected for the study. RESULTS: The prevalence of dermatophytoses was 11.2% with tinea capitis being the most common type while the grey patch form being the dominant clinical manifestation. There was a significant difference (p = 0.001) in dermatophytoses in different schools with Olympic primary school registering the highest prevalence (22.6%). The highest infection rate occurred among six to eight years age bracket in both sexes compared to other age brackets (p = 0.002). The genera of fungi associated with dermatophytoses were isolated indicating the number in each species as follows; T. violecium (35), T. mentagrophytes(3), T. terestre(3), T. schoenleinii(2), and T. interdigitale(1), M. canis(2), M. equinum(1) and E. flocossum(1). T. violecium was the predominant species isolated, at 35/48 (71%) followed by T. mentagrophytes and T. terrestre at 3/48 (6%) each. CONCLUSION: The study indicates high prevalence of 11.2% dermatophyte infection among the school children in Kibera. Factors contributing to the high frequency and chronic occurrences of ring worm in this area may include poor living environment, children interaction patterns and poor health seeking behaviour. There is need for health education and public awareness campaigns among the communities in urban informal settlements on healthy seeking behaviors and hygiene in order to reduce transmission and severe clinical manifestations.

Pregnancy rates among female participants in phase I and phase IIA AIDS vaccine clinical trials in Kenya.

BACKGROUND: Female participants in AIDS candidate vaccine clinical trials must agree to use effective contraception to be enrolled into the studies, and for a specified period after vaccination, since the candidate vaccines' effects on the embryo or foetus are unknown. OBJECTIVES: To review data on female participants' pregnancy rates from phase I and IIA AIDS vaccine clinical trials conducted at the Kenya AIDS Vaccine Initiative (KAVI) and to discuss the challenges of contraception among female participants. DESIGN: Descriptive observational retrospective study. SETTING: KAVI clinical trial site, Kenyatta National Hospital and University of Nairobi, Kenya. SUBJECTS: Thirty nine female participants were enrolled into these trials. They received family planning counselling and were offered a choice of different contraceptive methods, as per the protocols. All contraception methods chosen by the participants were offered at the study site at no cost to the participant. RESULTS: Four women conceived during the study period when pregnancies were to be avoided. All four had opted for sexual abstinence as a contraceptive method, but reported having been coerced by their partners to have unprotected sexual intercourse. CONCLUSION: Abstinence is clearly not a reliable contraceptive option for women in developing-country settings. Effective female-controlled contraceptives, administered at the clinical trial site, may empower female participants to better control their fertility, leading to more complete clinical trial data.

Herpes simplex virus type 2 infection among young uncircumcised men in Kisumu, Kenya.

OBJECTIVES: To identify factors associated with herpes simplex virus type 2 (HSV-2) infection among men aged 18-24 in Kisumu, Kenya. METHODS: Baseline data from a randomised trial of male circumcision were analysed. Participants were interviewed for sociodemographic and behavioural risks. The outcome was HSV-2 by antibody status. Risk factors were considered singly and in combination through logistic regression models. RESULTS: Among 2771 uncircumcised men, 766 (27.6%; 95% confidence interval (CI) 26.0% to 29.3%) tested antibody positive for HSV-2. The median age at first sex was 16 years, and the median number of lifetime sexual partners was four. HSV-2 seroprevalence increased from 19% among 18-year-olds to 43% among 24-year-olds (p<0.001). In multivariable analysis, statistically significant risks for infection were increasing age (adjusted odds ratio (AOR) = 1.22-2.58), being married or having a live-in female partner (AOR = 1.80; 95% CI 1.28 to 2.53), preferring "dry" sex (AOR = 1.39; 95% CI 1.14 to 1.69), reported penile cuts or abrasions during sex (AOR = 1.58; 95% CI 1.32 to 1.91), increasing lifetime sex partners (multiple response categories; AORs ranging from 1.65 to 1.97), and non-student occupation (multiple response categories; AORs ranging from 1.44 to 1.93). Risk decreased with reported condom used at last sex (AOR = 0.82; 95% CI 0.68 to 0.99). CONCLUSION: Primary prevention efforts should be initiated at an early age. The same behavioural interventions used currently for HIV prevention-abstinence, reducing the number of sex partners and increasing condom use-should be effective for HSV-2 prevention.

Antibody to Rmp (outer membrane protein 3) increases susceptibility to gonococcal infection.

The severe adverse effects of gonococcal infection on human fertility suggests that Neisseria gonorrhoeae would exert powerful selection for the development of a protective immune response in humans. N. gonorrhoeae is an obligate human pathogen and must persist in humans to survive. Since it is an ecologically successful organism, it must have evolved strategies to evade any human immune response it elicits. In a longitudinal study among 243 women working as prostitutes and experiencing frequent gonococcal infection, younger women, women with HIV infection, and women with antibody to the gonococcal outer membrane protein 3 (Rmp) were at increased risk of infection (adjusted odds ratio 3.4, CI95% 1.1-10.4, P < 0.05). Rmp is highly conserved in N. gonorrhoeae and the blocking of mucosal defences may be one of its functions. As similar proteins occur in many gram negative mucosal pathogens, the enhancing effect of such proteins may be a general strategy whereby bacteria evade human immune responses.

PIP: Between March 1985 and July 1986 researchers enrolled 243 female prostitutes in Pumwani community of Nairobi, Kenya, in a longitudinal study to examine the relationship between the antibody to the gonococcal outer membrane protein 3 (Rmp Ab) and gonococcal mucosal infection. Few women used condoms. 69% were HIV-1 seropositive. Just 9.5% (23) of the women had not had any gonococcal infections, despite probable exposure to them, indicating the possibility of some acquired protective immunity to Neisseria gonorrhoea. 90.5% had had at least 1 gonococcal infection. Women with Rmp Ab faced a greater risk of gonococcal infection than those who were Rmp Ab negative (OR = 3.4;l p .05), denoting that Rmp Ab increases susceptibility to gonococcal mucosal infections. Women older than 29 years were at lower risk of gonococcal infection than those younger than 29 years (odds ratio [OR] = 0.3; p .03). Women who used oral contraceptives (OCs) were also likely to be infected with N. gonorrhoea (OR = 3; p = .062). Further, 31% of OC users had cervical ectopy compared to just 14% of nonusers (OR = 2.8; p .005), suggesting that the effect of OCs on the cervix make it more susceptible to gonococcal infection. Rmp Ab also exists in many other gram-negative mucosal pathogens, often playing the same role as it does in N. gonorrhoea infection. Thus, Rmp Ab may be a common scheme bacteria used to elude human immune responses. These findings provide more understanding as to why N. gonorrhoea is an ecologically successful human pathogen.

Antibodies to opacity proteins (Opa) correlate with a reduced risk of gonococcal salpingitis.

Acute salpingitis complicating cervical gonococcal infection is a significant cause of infertility. Relatively little data are available concerning the pathophysiologic mechanisms of this disease. A cohort of 243 prostitutes residing in Nairobi were followed between March 1985 and April 1988. Gonococcal cultures were performed at each visit, and acute salpingitis was diagnosed clinically. Serum at enrollment was tested by immunoblot for antibody to gonococcal outer membrane proteins. 8.6% (146/1689) of gonococcal infections were complicated by salpingitis. Increased risk of salpingitis was associated with younger age, shorter duration of prostitution, HIV infection, number of gonococcal infections, and episodes of nongonococcal salpingitis. Rmp antibody increased the risk of salpingitis. Antibody to Opa decreased the risk of salpingitis. By logistic regression analysis, antibody to Opa was independently associated with decreased risk of gonococcal salpingitis (adjusted odds ratio [OR], 0.35; 95% confidence interval [95%CI], 0.17-0.76); HIV infection (adjusted OR, 3.5; 95% CI, 0.96-12.8) and episodes of nongonococcal salpingitis (adjusted OR, 3.4; 95% CI, 1.8-6.4) were independently associated with an increased risk of salpingitis. Antibody to Opa appears to protect against ascending gonococcal infection, perhaps by interfering with Opa mediated adherence and endocytosis. The demonstration of natural immunity that protects against upper genital tract infection in women suggests that a vaccine to prevent gonococcal salpingitis is possible.

Epidemiologic evidence for the development of serovar-specific immunity after gonococcal infection.

We tested the hypothesis that strain-specific immunity occurs after gonococcal infection in a longitudinal study of 227 prostitutes resident in one small community who experienced frequent gonococcal infections. Women were examined and cultured for Neisseria gonorrhoeae at 2-wk intervals. Gonococcal isolates were typed according to protein 1 serovar, auxotype, and beta-lactamase plasmid type, and classified as to serovar and strain. The hypothesis was tested by comparing the predictions of the hypothesis with the observations of the study. Over the 14-mo period of the study, major changes in the prevalence of specific serovars were observed in the gonococcal population infecting these women. Women with HIV infection experienced a higher rate of gonococcal infection (0.56 +/- 0.03 vs. 0.46 +/- 0.04, P less than 0.05, t test) compared with HIV-negative women and were more likely to experience multiple infections with the same strain. The duration of prostitution was inversely related to the frequency of gonococcal infection. Women experiencing an infection with a specific gonococcal serovar were at a 2- to 10-fold reduced risk of reinfection with the same serovar, except for the 1B-1 serovar. The results of the study were consistent with all four predictions of the hypothesis. Infection with a specific gonococcal serovar results in specific but incomplete protection against subsequent infection with the homologous serovar. The mechanism of this protection remains to be determined.

HIV-1 target cells in foreskins of African men with varying histories of sexually transmitted infections.

Numerous epidemiologic studies have found significant associations between lack of circumcision and HIV-1 acquisition in men. To our knowledge, this is the first study of human foreskin tissue that examines biologic mechanisms that increase susceptibility of uncircumcised African men to HIV-1. Foreskin specimens from 20 men with and 19 men with no history of sexually transmitted infections were examined for HIV-1 target cells. Most Langerhans cells were found in the epithelium; most CD4+ T cells and macrophages were in the submucosa. There were no differences in HIV-1 target cells between men with and those without history of sexually transmitted infections. However Langerhans cells and macrophages were more abundant in the group with a history of infection. The densities and positions of HIV-1 target cells in the foreskin tissue of these Kenyan men indicate that the inner mucosal surface of the human foreskin contains cells that make it highly susceptible to HIV infection.

No evidence for rapid subtype C spread within an epidemic in which multiple subtypes and intersubtype recombinants circulate.

There are multiple subtypes of HIV-1 circulating worldwide, but recently, subtype C has become highly prevalent, particularly in certain geographic regions. It is unclear whether the dominance of subtype C or other subtypes is due to increased fitness of certain subtypes for transmission, or a founder effect in new, rapidly growing epidemics. To examine whether the prevalence of one subtype increases over the course of an expanding epidemic that includes several circulating subtypes, we examined the distribution of HIV-1 subtypes in Kenya from 1986 to 2000. We found no evidence for an increase in the prevalence of subtype C, which remained low throughout this approximately 15-year period. Interestingly, the percentage of subtype D present in the population decreased significantly over that period, with a slight increase in subtype A. Throughout that period, intersubtype recombinant viruses were detected, including at the early stages of the epidemic. This latter finding suggests that reinfection may have occurred in high-risk groups early in the epidemic, leading to intersubtype recombinant viruses that underwent secondary spread.

Human immunodeficiency virus infection in long-distance truck drivers in east Africa.

BACKGROUND: A cross-sectional survey was performed to determine the seroprevalence and correlates of human immunodeficiency virus (HIV) infection among long-distance truck drivers in Kenya. METHODS: Truck drivers along the Mombasa-Nairobi highway were enrolled at a roadside research clinic. A standardized interview and serologic evaluation for HIV and syphilis were conducted. RESULTS: We enrolled 970 truck drivers and their assistants of whom 257 (27%) had HIV antibodies. In univariate analysis, HIV infection was correlated with older age, non-Kenyan nationality, Christian religion, longer duration of truck driving, travel outside of Kenya, less frequent visits to wives, and more frequent visits to prostitutes. Uncircumcised status, history of genital ulcer disease or urethritis during the previous 5 years, and a positive Treponema pallidum hemagglutination assay for syphilis were each associated with positive HIV serostatus. Univariate correlates of uncircumcised status included younger age, non-Kenyan nationality, Christian religion, travel outside of Kenya, and less frequent visits to prostitutes. There was a significant association between uncircumcised status and 5-year history of genital ulcer disease or serologic evidence of syphilis, but not with 5-year history of urethritis. In multivariate analysis, HIV infection was independently associated with uncircumcised status (adjusted odds ratio [OR], 4.9; 95% confidence interval [CI], 2.8 to 8.4), history of genital ulcer disease (adjusted OR, 2.4; 95% CI, 1.5 to 4.1), history of urethritis (adjusted OR, 1.8; 95% CI, 1.1 to 2.9), more frequent sex with prostitutes (more than once per month; adjusted OR, 1.7; 95% CI, 1.1 to 2.8), and positive T pallidum hemagglutination assay (adjusted OR, 1.2; 95% CI, 1.0 to 1.4). The attributable risk percentage for the association between HIV and uncircumcised status was 70%, and the population attributable risk was 25%. CONCLUSIONS: Truck drivers in east Africa are at high risk of HIV infection. The strongest correlates of HIV seropositivity were uncircumcised status and history of both ulcerative and nonulcerative sexually transmitted diseases.

HIV-1 and immunological changes during pregnancy: a comparison between HIV-1-seropositive and HIV-1-seronegative women in Nairobi, Kenya.

OBJECTIVE: To assess changes in the proportion of CD4 and CD8 T-lymphocyte profiles during pregnancy, at delivery and postpartum, and to determine whether HIV-1 infection affects the normal profile. DESIGN AND METHODS: A total of 416 pregnant HIV-1-infected women and an age and parity-matched HIV-seronegative group of 407 pregnant women were enrolled into a prospective study on the impact of HIV-1 infection on pregnancy. Maternal blood was obtained for lymphocyte subset determination at enrollment, delivery and 6 weeks postpartum. Whole blood sample drawn in EDTA-containing tubes were used to determine T-helper/inducer (CD4) and T-suppressor/cytotoxic (CD8) cells by direct immunofluorescence using monoclonal antibodies. RESULTS: No relationship was found between gestational age and any immunological variable. The CD4 percentage was lower postpartum than antenatally, in both HIV-1-seropositive and seronegative women, but this was not true for absolute CD4 counts. CD8 absolute counts and percentages were significantly higher postpartum than antenatally. The differences between HIV-1-seropositive and seronegative women in changes over pregnancy in CD4 and CD8 cells and their ratio, were not statistically significant. CONCLUSION: Our findings do not support a short-term synergistic effect of HIV-1 and pregnancy on the immune function as determined by T-lymphocyte subsets.

PIP: The impact of HIV-1 on pregnancy was investigated in a prospective case-control study of 416 pregnant HIV-infected women and 407 age- and parity-matched pregnant HIV-seronegative women from Nairobi, Kenya. No relationship existed between gestational age (14-30 weeks) and any hematologic or immunologic variable studied. In both cases and controls, the CD4 percentage (but not absolute count) was lower postpartum than during pregnancy, while CD8 absolute counts and percentages were significantly higher in the postpartum period. The differences between HIV-positive and HIV-negative women in changes during pregnancy in CD4 and CD8 cells and their ratio were not statistically significant. These findings fail to provide support for a synergistic effect of HIV-1 and pregnancy on immune function. Further studies are needed, however, to assess the long-term effects of pregnancy in HIV-infected women, to determine the impact of pregnancy at different stages of HIV disease, and to establish normal and HIV-1-related T-lymphocyte subset profiles during the entire course of pregnancy in African women.

The importance of core groups in the epidemiology and control of HIV-1 infection.

PIP: In Africa, HIV transmission occurs mainly through heterosexual intercourse. High-frequency transmitter core groups are key to the epidemiology of HIV-1 and STD on the continent. The rapid growth of the HIV-1 epidemic in Africa appears to have resulted, in part, from social and economic factors which result in individuals' frequent engagement in sexual intercourse with members of HIV-infected core groups. Understanding the importance of core groups in HIV-1 transmission is therefore key to developing more effective programs for the control of HIV-1. Sections explore the core groups concept and the sexual transmission of infection, social and economic forces creating core groups in Africa, the interaction of STD and HIV-1 in core groups, the effect of STD on HIV-1 disease progression in core groups in accelerating the HIV-1 epidemic, the role of core group interventions in control programs, balancing disease control with the potential for victimization, and research needs.^ieng

Rapid increase of both HIV-1 infection and syphilis among pregnant women in Nairobi, Kenya.

OBJECTIVE: To determine the prevalence of HIV-1 and syphilis antibodies in a population of pregnant women in Nairobi, Kenya, between 1989 and 1991. METHODS: As part of an ongoing prospective study on the effect of HIV-1 infection and sexually transmitted diseases, 4883 pregnant women were screened for HIV-1 and syphilis antibodies in one health-centre in Nairobi. RESULTS: HIV-1 seroprevalence increased from 6.5 to 13.0% (P < 0.001) and syphilis seroreactivity from 2.9 to 5.3% (P = 0.002), while there was no change in gonococcal infection rates. The most rapid increase in HIV-1 prevalence was observed in women aged less than 25 years. There was no evidence of demographic fluctuations in the population during this time, or of changes in sexual behaviour, except that fewer women enrolled in 1991 reported having more than one sex partner, compared with women enrolled in 1989 (39.1 versus 20.0%; P = 0.0001). HIV-1-seropositive women were more likely to be seroreactive for syphilis than HIV-1-seronegative mothers (7.7 versus 3.2%; odds ratio = 2.5; 95% confidence interval, 1.7-3.8; P < 0.001), but there was no difference between the two groups in terms of gonorrhoea prevalence. CONCLUSION: These data confirm an association between HIV-1 and syphilis infection, and indicate that both are spreading rapidly among women in Nairobi outside high-risk groups. Increased efforts to control both infections are urgently required.

PIP: Between January 1989 and December 1991, health workers took blood samples from 4883 pregnant women attending the Nairobi City Commission's Langata Clinic in Nairobi, Kenya to determine demographic factors and indicators of sexual behavior to explain the increase in HIV-1 infection and syphilis among these women of low socioeconomic status. HIV-1 seroprevalence stood at 8.8%. Syphilis seroreactivity was 3.6%. HIV-1 seropositive mothers were 2.5 times more likely to also test positive for syphilis than were HIV-1 seronegative mothers (7.7% vs. 3.2%; p.001). There was no significant association between HIV-1 seropositivity and gonococcal infection rate (7.3% vs. 8.9%), however. Women who tested HIV-1 positive tended to be from western Kenya (60.1% vs. 39.1%; p.0001). Between 1989 and 1991, annual HIV-1 seroprevalence rates increased from 6.5% to 13% (p.001) as did annual syphilis seroreactivity rates (2.9-5.3%; p=.02). The HIV-1 seroprevalence rates remained high, but did not rise significantly among syphilis seroreactive women between 1989 and 1991 (17.9-20.7%). They did rise among syphilis seronegative women (6.9-12.5%; p.0001), however. The HIV-1 infection rate increase was greater among 25-year old women (5.6-13.2%; p.001) than it was among 25-year old women (6.8-12.7%; p=.09). Indeed the annual incidence rate for 25-year old women was 3-4%. Between 1989-1991, there was a decrease in the percentage of both HIV-1 seropositive and seronegative women who had had 1 sex partner during the last 2 years (39.1% vs. 20%; p=.0001). Demographic factors remained the same throughout the study period. These results verified the link between HIV-1 infection and syphilis and their rapid rise among women in low risk groups. Thus there was a pressing need to improve HIV-1 and sexually transmitted disease prevention programs.

Controlling HIV in Africa: effectiveness and cost of an intervention in a high-frequency STD transmitter core group.

Since 1985, a population of over 1,000 predominantly HIV-positive female prostitutes residing in a low-income area of Nairobi, has been enrolled in a sexually transmitted disease (STD)/HIV control programme. The major elements of the programme include the diagnosis and treatment of conventional STD, and the promotion of condom use to prevent the transmission of HIV and other sexually transmitted infections. Using estimates of numbers of HIV-seropositive prostitutes, numbers of sexual contacts, susceptibility of clients to HIV, HIV transmission efficiency, rates of condom use and the basic reproductive rate of HIV infection in Kenya, we estimate that the programme is responsible for preventing between 6,000 and 10,000 new cases of HIV infection per year among clients and contacts of clients. The total annual operating cost of the programme is approximately US$77,000 or between US$8.00 and US$12.00 for each case of HIV infection prevented. Programmes to reduce the transmission of HIV and other sexually transmitted infections which are targeted at high-frequency STD transmitters, such as prostitutes, can be effective and relatively inexpensive to undertake. More such programmes should be developed and evaluated in different settings.

Acceptability of HIV vaccine trials in high-risk heterosexual cohorts in Mombasa, Kenya.

OBJECTIVES: To ascertain the level of acceptance of a prophylactic HIV vaccine trial in high-risk HIV-seronegative heterosexual cohorts of men and women in Mombasa, Kenya, and to assess the anticipated effects of participation on risk behavior. METHODS: Standardized questionnaire administered to a convenience sample of commercial sex workers and trucking company employees enrolled in prospective cohort studies. RESULTS: Ninety-six per cent of respondents believed that HIV was a major problem in Kenya and 86% of men and 94% of women perceived themselves at risk. One hundred per cent of women and 84% of men expressed interest in participation in an HIV vaccine trial, after explanation of the experimental nature of the vaccine, double-blind placebo-controlled design, prolonged follow-up and potential change in serostatus. Seventeen per cent of men and 9% of women anticipated an increase in risk behavior as a result of participation. CONCLUSION: The majority of individuals in two high-risk cohorts were interested in participating in Phase III efficacy trials of HIV vaccines. A significant minority anticipated an increase in risk behavior, which emphasizes the need for intensive counseling and education throughout a vaccine trial.

PIP: The acceptability of a theoretical human immunodeficiency virus (HIV) vaccine trial was investigated in HIV-negative commercial sex workers and trucking company employees in Mombasa, Kenya. The 206 women and 201 men who completed questionnaires were already enrolled in a prospective cohort study of high-risk heterosexuals. 95% of men and 98% of women surveyed agreed that acquired immunodeficiency syndrome (AIDS) is a major problem in Kenya; however, only 14% and 6%, respectively, considered themselves at personal risk of infection. Only 4% of male and 1% of female respondents stated they would refuse an HIV vaccine of proven safety and efficacy. However, 91% of women but only 67% of men indicated they would participate in a double-blind, placebo-controlled vaccine trial that involved vaccine-induced HIV seropositivity and prolonged follow-up. The main concerns about participation in such a trial were the positive HIV blood test result and fear of acquiring HIV from the vaccine. 9% of men and 6% of women anticipated they would decrease their condom use as a result of participation in such a trial, and 9% of men and 3% of women thought they would increase their number of sexual partners. Anticipated higher risk behavior was significantly associated with male gender, but not with age, education, history of prostitution or of sex with prostitutes, or current condom use. If and when vaccine trials become possible, this high-risk cohort would comprise an ideal target population; however, concurrent counseling about the need to continue preventive behavioral measures would be a necessity.