Peter N. Kazembe

Reduction of concentration of HIV-1 in semen after treatment of urethritis: implications for prevention of sexual transmission of HIV-1

BACKGROUND Transmission of HIV-1 is predominantly by heterosexual contact in sub-Saharan Africa, where sexually transmitted diseases (STDs) are also common. Epidemiological studies suggest that STDs facilitate transmission of HIV-1, but the biological mechanism remains unclear. We investigated the hypothesis that STDs increase the likelihood of transmission of HIV-1 through increased concentration of the virus in semen. METHODS HIV-1 RNA concentrations were measured in seminal and blood plasma from 135 HIV-1-seropositive men in Malawi; 86 had urethritis and 49 controls did not have urethritis. Men with urethritis received antibiotic treatment according to the guidelines of the Malawian STD Advisory Committee. Samples were analysed at baseline and at week 1 and week 2 after antibiotic therapy in urethritis patients, and at baseline and week 2 in the control group. FINDINGS HIV-1-seropositive men with urethritis had HIV-1 RNA concentrations in seminal plasma eight times higher than those in seropositive men without urethritis (12.4 vs 1.51 x 10(4) copies/mL, p = 0.035), despite similar CD4 counts and concentrations of blood plasma viral RNA. Gonorrhoea was associated with the greatest concentration of HIV-1 in semen (15.8 x 10(4) copies/mL). After the urethritis patients received antimicrobial therapy directed against STDs, the concentration of HIV-1 RNA in semen decreased significantly (from 12.4 x 10(4) copies/mL to 8.91 x 10(4) copies/mL at 1 week [p = 0.03] and 4.12 x 10(4) copies/mL at 2 weeks [p = 0.0001]). Blood plasma viral RNA concentrations did not change. There was no significant change in seminal plasma HIV-1 RNA concentrations during the 2-week period in the control group (p = 0.421). INTERPRETATION These results suggest that urethritis increases the infectiousness of men with HIV-1 infection. HIV-1-control programmes, which include detection and treatment of STDs in patients already infected with HIV-1, may help to curb the epidemic. Targeting of gonococcal urethritis may be a particularly effective strategy.

Reemergence of Chloroquine-Sensitive Plasmodium falciparum Malaria after Cessation of Chloroquine Use in Malawi

In 1993, Malawi became the first African country to replace chloroquine with sulfadoxine-pyrimethamine nationwide in response to high rates of chloroquine-resistant falciparum malaria. To determine whether withdrawal of chloroquine can lead to the reemergence of chloroquine sensitivity, the prevalence of the pfcrt 76T molecular marker for chloroquine-resistant Plasmodium falciparum malaria was retrospectively measured in Blantyre, Malawi. The prevalence of the chloroquine-resistant pfcrt genotype decreased from 85% in 1992 to 13% in 2000. In 2001, chloroquine cleared 100% of 63 asymptomatic P. falciparum infections, no isolates were resistant to chloroquine in vitro, and no infections with the chloroquine-resistant pfcrt genotype were detected. A concerted national effort to withdraw chloroquine from use has been followed by a return of chloroquine-sensitive falciparum malaria in Malawi. The reintroduction of chloroquine, ideally in combination with another antimalarial drug, should be considered in areas where chloroquine resistance has declined and safe and affordable alternatives remain unavailable.

Quantitating the Multiplicity of Infection with Human Immunodeficiency Virus Type 1 Subtype C Reveals a Non-Poisson Distribution of Transmitted Variants

ABSTRACT Identifying the specific genetic characteristics of successfully transmitted variants may prove central to the development of effective vaccine and microbicide interventions. Although human immunodeficiency virus transmission is associated with a population bottleneck, the extent to which different factors influence the diversity of transmitted viruses is unclear. We estimate here the number of transmitted variants in 69 heterosexual men and women with primary subtype C infections. From 1,505 env sequences obtained using a single genome amplification approach we show that 78% of infections involved single variant transmission and 22% involved multiple variant transmissions (median of 3). We found evidence for mutations selected for cytotoxic-T-lymphocyte or antibody escape and a high prevalence of recombination in individuals infected with multiple variants representing another potential escape pathway in these individuals. In a combined analysis of 171 subtype B and C transmission events, we found that infection with more than one variant does not follow a Poisson distribution, indicating that transmission of individual virions cannot be seen as independent events, each occurring with low probability. While most transmissions resulted from a single infectious unit, multiple variant transmissions represent a significant fraction of transmission events, suggesting that there may be important mechanistic differences between these groups that are not yet understood.

Neonatal sepsis: an international perspective.

Neonatal infections currently cause about 1.6 million deaths annually in developing countries. Sepsis and meningitis are responsible for most of these deaths. Resistance to commonly used antibiotics is emerging and constitutes an important problem world wide. To reduce global neonatal mortality, strategies of proven efficacy, such as hand washing, barrier nursing, restriction of antibiotic use, and rationalisation of admission to neonatal units, need to be implemented. Different approaches require further research.

Increased prevalence of malaria in HIV-infected pregnant women and its implications for malaria control.

Summary objectives  To examine in pregnant women the relationship between HIV infection and malaria prevalence and to determine, in relation to HIV infection, the effectiveness of sulphadoxine‐pyrimethamine in clearing P. falciparum infection.

An evaluation of the effects of intermittent sulfadoxine-pyrimethamine treatment in pregnancy on parasite clearance and risk of low birthweight in rural Malawi

The prevalence of infection with malarial parasites and the incidence of anaemia and delivery of infants with low birthweight (LBW) were investigated in 575 Malawian mothers who received one, two or three doses of sulfadoxine-pyrimethamine (SP) during pregnancy. All the subjects were enrolled at their first antenatal visit and all delivered at hospital. The prevalence of Plasmodium falciparum infection at first antenatal visit was 35.3% in primigravidae and 13.6% in multigravidae (P < 0.001). Mean haemoglobin concentration was significantly lower in primigravidae than in multigravidae (8.8 v. 9.5 g/dl; P < 0.001). Of the 233 women tested for HIV infection, 18.8% of the primigravidae and 23.7% of the multigravidae were seropositive. At delivery, there was no significant difference in parasite prevalence in peripheral or placental blood between women who had received one or two antenatal doses of SP. The multigravidae who had received two doses of SP had higher mean haemoglobin concentrations than those who had received just one (P = 0.009) [this difference was not seen in the primigravidae (P = 0.92)]. However, linear regression analysis indicated that the haematinic supplements given to the subjects contributed more to this increase in haemoglobin concentration than the SP. The mean birthweights were higher, and incidence of LBW lower in babies born to primi-and multi-gravidae who had received two or three doses of SP treatment than those seen in babies born to women who had had just one dose (P < 0.03 for each). The odds ratio for LBW in primigravidae compared with multigravidae decreased from 3.2 to 1.0 as the number of SP doses increased from one to three. The benefit of three doses (compared with none) was equivalent to the population-attributable risk of LBW in primigravidae being reduced from 34.6% to 0%. Subjects who were seropositive for HIV were twice as likely to give birth to LBW babies as the other subjects. The use of SP was not associated with maternal side-effects or perinatal complications. The present results indicate that multiple doses of SP taken during pregnancy will lead to a highly significant reduction in the incidence of LBW in infants born to primigravidae, even if the women have HIV infections. This reduction is observable even when parasite prevalence at delivery is high because of re-infections in late pregnancy; reduction in parasite prevalence earlier in pregnancy, as the result of SP treatment, leads to improved foetal growth.

Trichomonas vaginalis as a cause of urethritis in Malawian men.

BACKGROUND AND OBJECTIVES Trichomonas vaginalis is one of the most common sexually transmitted infections. In Malawi, rates of trichomoniasis in women are high. The prevalence of T. vaginalis infection in men is expected to be high but has not previously been documented. GOALS We sought to determine the prevalence of trichomoniasis in Malawian men with and without urethritis, to evaluate a polymerase chain reaction detection assay for T. vaginalis in urethral swabs and to examine the effect of T. vaginalis infection on excretion of human immunodeficiency virus (HIV) in semen. STUDY DESIGN Men presenting at the Sexually Transmitted Diseases (STD) and Dermatology Clinics in Malawi were enrolled in a cross-sectional study. We compared a polymerase chain reaction-based test for T. vaginalis detection with wet-mount microscopy and culture of urethral swabs. HIV serology was determined by enzyme-linked immunosorbent assay (ELISA), and HIV-1 RNA concentrations in semen were measured by quantitative nucleic acid sequence-based analysis. RESULTS T. vaginalis was detected in 51 of 293 men. The estimated prevalence among symptomatic men was 20.8% and among asymptomatic men, 12.2%. Polymerase chain reaction performed with a sensitivity of 0.82 (95% CI: 0.66-0.92) and specificity of 0.95 (95% CI: 0.91-0.97) compared to wet-mount microscopy and culture. There was no difference in the rate of HIV seropositivity in men with and without T. vaginalis infection. However, in men with symptomatic urethritis, the median HIV RNA concentration in seminal plasma from men with T. vaginalis was significantly higher that in seminal plasma from HIV-positive men without trichomonas.

Frequent detection of acute primary HIV infection in men in Malawi.

Background: Acute (antibody-negative) HIV infection is associated with high transmission potential but is rarely recognized. Design: Cross-sectional study. Methods: We examined the prevalence and predictors of acute HIV infection among 1361 consecutive male outpatients attending sexually transmitted disease (STD; n = 929) and dermatology (n = 432) clinics in Lilongwe, Malawi. Serum specimens negative for HIV antibodies were screened by HIV RNA PCR using a highly specific pooling/resolution testing algorithm. Results: Five-hundred and fifty-three men (40.6%) were HIV antibody positive and 24 (1.8%) had acute HIV infection; 23 of 24 acutely infected men were from the STD clinic, where they represented 4.5% of all HIV antibody-negative men and 5.0% of all HIV infections. HIV RNA levels for acutely infected men were significantly higher [median (interquartile range), 6.10 (5.19–6.54) log10 HIV RNA copies/ml] than for 58 HIV antibody-positive men [4.42 (3.91–4.95) log10 copies/ml; P < 0.0001]. The factor most strongly associated with acute HIV infection was STD clinic attendance: (odds ratio, 15.2; 95% confidence interval, 2.04–113.0). In multivariate analysis considering only STD patients, factors associated with acute HIV infection included inguinal adenopathy, genital ulceration and age 24–26 years, the age stratum associated with peak incidence of HIV infection among Malawian men. Conclusions: Traditional HIV antibody tests alone are not sufficient to exclude HIV infection among men with acute STD in Malawi due to a surprising proportion of acute HIV infections in this population. Alternative screening methods are required for diagnosis of acute HIV infection; such screening could be important for research and for prevention of the sexual transmission of HIV in select populations.

Association of CD4 Cell Depletion and Elevated Blood and Seminal Plasma Human Immunodeficiency Virus Type 1 (HIV-1) RNA Concentrations with Genital Ulcer Disease in HIV-1-Infected Men in Malawi

CD4 cell counts and blood plasma and seminal plasma human immunodeficiency virus type 1 (HIV-1) concentrations were compared in HIV-1 RNA-seropositive men with urethritis and with or without genital ulcer disease (GUD). GUD was associated with lower CD4 cell counts (median, 258 vs. 348/microL) and increased blood plasma HIV-1 RNA (median, 240 x 10[3] vs. 79.4 x 10[3] copies/mL). Men with nongonococcal urethritis and GUD shed significantly greater quantities of HIV-1 in semen (median, 195 x 10[3] vs. 4.0 x 10[3] copies/mL) than men with nongonococcal urethritis without GUD. These levels decreased approximately 4-fold following antibiotic therapy. The results indicate an association between GUD and increased blood HIV-1 RNA levels. Increased HIV-1 in semen was demonstrated in some men with GUD; such an increase could lead to increased transmission, thus complicating interpretation of the role of the genital ulcer itself in the infectiousness of HIV. Reasons for increased HIV RNA in semen in men with GUD remain to be determined.

High Levels of Human Immunodeficiency Virus Type 1 in Blood and Semen of Seropositive Men in Sub-Saharan Africa

High levels of human immunodeficiency virus type 1 (HIV-1) replication, as reflected in HIV-1 RNA concentrations in blood and semen, probably contribute to both rapid disease progression and enhanced sexual transmission. Semen and blood were collected from 49 Malawian and 61 US and Swiss (US/Swiss) HIV-1-seropositive men with similar CD4 cell counts and no urethritis or exposure to antiretroviral drugs. Median seminal plasma and blood plasma HIV-1 RNA concentrations were >3-fold (P = .034) and 5-fold (P = .0003) higher, respectively, in the Malawian men. Similar differences were observed in subsets of the Malawian and US/Swiss study groups matched individually for CD4 cell count (P = .035 and P < .002, respectively). These observations may help explain the high rates of HIV-1 sexual transmission and accelerated HIV-1 disease progression in sub-Saharan Africa.