Feasibility, safety, and impact of the RTS,S/AS01E malaria vaccine when implemented through national immunisation programmes: evaluation of cluster-randomised introduction of the vaccine in Ghana, Kenya, and Malawi

BACKGROUND

The RTS,S/AS01E malaria vaccine (RTS,S) was introduced by national immunisation programmes in Ghana, Kenya, and Malawi in 2019 in large-scale pilot schemes. We aimed to address questions about feasibility and impact, and to assess safety signals that had been observed in the phase 3 trial that included an excess of meningitis and cerebral malaria cases in RTS,S recipients, and the possibility of an excess of deaths among girls who received RTS,S than in controls, to inform decisions about wider use.

METHODS

In this prospective evaluation, 158 geographical clusters (66 districts in Ghana; 46 sub-counties in Kenya; and 46 groups of immunisation clinic catchment areas in Malawi) were randomly assigned to early or delayed introduction of RTS,S, with three doses to be administered between the ages of 5 months and 9 months and a fourth dose at the age of approximately 2 years. Primary outcomes of the evaluation, planned over 4 years, were mortality from all causes except injury (impact), hospital admission with severe malaria (impact), hospital admission with meningitis or cerebral malaria (safety), deaths in girls compared with boys (safety), and vaccination coverage (feasibility). Mortality was monitored in children aged 1-59 months throughout the pilot areas. Surveillance for meningitis and severe malaria was established in eight sentinel hospitals in Ghana, six in Kenya, and four in Malawi. Vaccine uptake was measured in surveys of children aged 12-23 months about 18 months after vaccine introduction. We estimated that sufficient data would have accrued after 24 months to evaluate each of the safety signals and the impact on severe malaria in a pooled analysis of the data from the three countries. We estimated incidence rate ratios (IRRs) by comparing the ratio of the number of events in children age-eligible to have received at least one dose of the vaccine (for safety outcomes), or age-eligible to have received three doses (for impact outcomes), to that in non-eligible age groups in implementation areas with the equivalent ratio in comparison areas. To establish whether there was evidence of a difference between girls and boys in the vaccine's impact on mortality, the female-to-male mortality ratio in age groups eligible to receive the vaccine (relative to the ratio in non-eligible children) was compared between implementation and comparison areas. Preliminary findings contributed to WHO's recommendation in 2021 for widespread use of RTS,S in areas of moderate-to-high malaria transmission.

FINDINGS

By April 30, 2021, 652 673 children had received at least one dose of RTS,S and 494 745 children had received three doses. Coverage of the first dose was 76% in Ghana, 79% in Kenya, and 73% in Malawi, and coverage of the third dose was 66% in Ghana, 62% in Kenya, and 62% in Malawi. 26 285 children aged 1-59 months were admitted to sentinel hospitals and 13 198 deaths were reported through mortality surveillance. Among children eligible to have received at least one dose of RTS,S, there was no evidence of an excess of meningitis or cerebral malaria cases in implementation areas compared with comparison areas (hospital admission with meningitis: IRR 0·63 [95% CI 0·22-1·79]; hospital admission with cerebral malaria: IRR 1·03 [95% CI 0·61-1·74]). The impact of RTS,S introduction on mortality was similar for girls and boys (relative mortality ratio 1·03 [95% CI 0·88-1·21]). Among children eligible for three vaccine doses, RTS,S introduction was associated with a 32% reduction (95% CI 5-51%) in hospital admission with severe malaria, and a 9% reduction (95% CI 0-18%) in all-cause mortality (excluding injury).

INTERPRETATION

In the first 2 years of implementation of RTS,S, the three primary doses were effectively deployed through national immunisation programmes. There was no evidence of the safety signals that had been observed in the phase 3 trial, and introduction of the vaccine was associated with substantial reductions in hospital admission with severe malaria. Evaluation continues to assess the impact of four doses of RTS,S.

FUNDING

Gavi, the Vaccine Alliance; the Global Fund to Fight AIDS, Tuberculosis and Malaria; and Unitaid.

Mass Relapse Prevention to Reduce Transmission of Plasmodium vivax- A Systematic Review

Several temperate countries have used mass chemoprevention interventions with medicines of the 8-aminoquinoline class that prevent relapses from Plasmodium vivax before peak transmission to reduce transmission of malaria. The WHO commissioned a systematic review of the literature and evidence synthesis to inform development of recommendations regarding this intervention referred to as "mass relapse prevention" (MRP). Electronic databases were searched, 866 articles screened, and 25 assessed for eligibility after a full-text review. Two nonrandomized studies were included, one from the Democratic People's Republic of Korea (391,357 participants) and the second from the Azerbaijan Soviet Socialist Republic (∼30,000 participants). The two studies administered a single round of primaquine over 14 days (0.25 mg/kg per day). From 1 to 3 months after the treatment round, the incidence of P. vivax infections was significantly lower in areas that received MRP than those that did not (pooled rate ratio [RR] 0.08, 95% CI 0.07-0.08). At 4 to 12 months after the treatment round, the prevalence of P. vivax infection was significantly lower in MRP villages than non-MRP villages (odds ratio 0.12, 95% CI 0.03-0.52). No severe adverse events were found. The certainty of evidence for all outcomes was very low and no conclusions as to the effectiveness or safety of MRP could be drawn. However, it is not likely that this intervention will be needed in the future as most temperate countries where P. vivax is transmitted are nearing or have already eliminated malaria.

Could less be more? Accounting for fractional-dose regimens and different number of vaccine doses when measuring the impact of the RTS, S/AS01E malaria vaccine

BACKGROUND

The RTS, S/AS01E malaria vaccine (RTS, S) is recommended for children in moderate-to-high Plasmodium falciparum malaria transmission areas. This phase 2b trial (NCT03276962) evaluates RTS, S fractional- and full-dose regimens in Ghana and Kenya.

METHODS

1500 children aged 5-17 months were randomised (1:1:1:1:1) to receive RTS, S or rabies control vaccine. RTS, S groups received two full RTS, S doses at month (M)0/M1 followed by either full (groups R012-20, R012-14-26) or fractional (1/5) doses (groups Fx012-14-26, Fx017-20-32).

RESULTS

At M32 post-first dose, vaccine efficacy (VE) against clinical malaria (all episodes) ranged from 38% (R012-20; 95%CI: 24-49) to 53% (R012-14-26; 95%CI: 42-62). Vaccine impact estimates (cumulative number of malaria cases averted/1000 children vaccinated) were 1344 (R012-20), 2450 (R012-14-26), 2273 (Fx012-14-26), 2112 (Fx017-20-32). To account for differences in vaccine volume (fractional- versus full-dose), in a post-hoc analysis, we also estimated cases averted/1000 RTS, S full-dose equivalents: 336 (R012-20), 490 (R012-14-26), 874 (Fx012-14-26), 880 (Fx017-20-32).

CONCLUSIONS

VE against clinical malaria was similar in all RTS, S groups. Vaccine impact accounting for full-dose equivalence suggests that using fractional-dose regimens could be a viable dose-sparing strategy. If borne out through trial end (M50), these observations underscore the means to reduce cost per regimen with a goal of maximising impact and optimising supply.

Baseline malaria infection status and RTS,S/AS01E malaria vaccine efficacy

Background

The only licensed malaria vaccine, RTS,S/AS01 E , confers moderate protection against symptomatic disease. Because many malaria infections are asymptomatic, we conducted a large-scale longitudinal parasite genotyping study of samples from a clinical trial exploring how vaccine dosing regimen affects vaccine efficacy (VE).

Methods

1,500 children aged 5-17 months were randomized to receive four different RTS,S/AS01 E regimens or a rabies control vaccine in a phase 2b clinical trial in Ghana and Kenya. We evaluated the time to the first new genotypically detected infection and the total number of new infections during two follow-up periods in over 36K participant specimens. We performed a post hoc analysis of VE based on malaria infection status at first vaccination and force of infection.

Results

We observed significant and comparable VE (25-43%, 95% CI union 9-53%) against first new infection for all four RTS,S/AS01 E regimens across both follow-up periods (12 and 20 months). Each RTS,S/AS01 E regimen significantly reduced the number of new infections in the 20-month follow-up period (control mean 4.1 vs. RTS,S/AS01 E mean 2.6-3.0). VE against first new infection was significantly higher in participants who were malaria-infected (68%; 95% CI, 50 to 80%) versus uninfected (37%; 95% CI, 23 to 48%) at the first vaccination (P=0.0053) and in participants experiencing greater force of infection between dose 1 and 3 (P=0.059).

Conclusions

All tested dosing regimens blocked some infections to a similar degree. Improved VE in participants infected during vaccination could suggest new strategies for highly efficacious malaria vaccine development and implementation. ( ClinicalTrials.gov number, NCT03276962 ).

House modifications as a malaria control tool: how does local context shape participants' experience and interpretation in Uganda?

BACKGROUND

Evidence that house design can provide protection from malaria is growing. Housing modifications such as screening windows, doors, and ceilings, and attaching insecticide-impregnated materials to the eaves (the gap between the top of the wall and bottom of the roof), can protect against malaria. To be effective at scale, however, these modifications must be adopted by household residents. There is evidence that housing modifications can be acceptable, but in-depth knowledge on the experiences and interpretation of modifications is lacking. This qualitative study was carried out to provide a holistic account of the relationship between experiences and interpretations of four types of piloted housing modifications and the local context in Jinja, Uganda.

METHODS

Qualitative research was conducted between January to June 2021, before and during the installation of four types of housing modifications. The methods included nine weeks of participant observations in two study villages, nine focus group discussions with primary caregivers and heads of households (11-12 participants each), and nine key informant interviews with stakeholders and study team members.

RESULTS

Most residents supported the modifications. Experiences and interpretation of the housing modifications were shaped by the different types of housing in the area and the processes through which residents finished their houses, local forms of land and property ownership, and cultural and spiritual beliefs about houses.

CONCLUSIONS

To maximize the uptake and benefit of housing modifications against malaria, programme development needs to take local context into account. Forms of local land and house ownership, preferences, the social significance of housing types, and religious and spiritual ideas shape the responses to housing modifications in Jinja. These factors may be important in other setting. Trial registration Trial registration number is NCT04622241. The first draft was posted on November 9th 2020.

Plasmodium falciparum pfhrp2 and pfhrp3 Gene Deletions from Persons with Symptomatic Malaria Infection in Ethiopia, Kenya, Madagascar, and Rwanda

Histidine-rich protein 2 (HRP2)–based rapid diagnostic tests detect Plasmodium falciparum malaria and are used throughout sub-Saharan Africa. However, deletions in the pfhrp2 and related pfhrp3 (pfhrp2/3) genes threaten use of these tests. Therapeutic efficacy studies (TESs) enroll persons with symptomatic P. falciparum infection. We screened TES samples collected during 2016–2018 in Ethiopia, Kenya, Rwanda, and Madagascar for HRP2/3, pan-Plasmodium lactate dehydrogenase, and pan-Plasmodium aldolase antigen levels and selected samples with low levels of HRP2/3 for pfhrp2/3 genotyping. We observed deletion of pfhrp3 in samples from all countries except Kenya. Single-gene deletions in pfhrp2 were observed in 1.4% (95% CI 0.2%–4.8%) of Ethiopia samples and in 0.6% (95% CI 0.2%–1.6%) of Madagascar samples, and dual pfhrp2/3 deletions were noted in 2.0% (95% CI 0.4%–5.9%) of Ethiopia samples. Although this study was not powered for precise prevalence estimates, evaluating TES samples revealed a low prevalence of pfhrp2/3 deletions in most sites.

Opening the 'black box' of collaborative improvement: a qualitative evaluation of a pilot intervention to improve quality of malaria surveillance data in public health centres in Uganda

BACKGROUND

Demand for high-quality surveillance data for malaria, and other diseases, is greater than ever before. In Uganda, the primary source of malaria surveillance data is the Health Management Information System (HMIS). However, HMIS data may be incomplete, inaccurate or delayed. Collaborative improvement (CI) is a quality improvement intervention developed in high-income countries, which has been advocated for low-resource settings. In Kayunga, Uganda, a pilot study of CI was conducted in five public health centres, documenting a positive effect on the quality of HMIS and malaria surveillance data. A qualitative evaluation was conducted concurrently to investigate the mechanisms of effect and unintended consequences of the intervention, aiming to inform future implementation of CI.

METHODS

The study intervention targeted health workers, including brief in-service training, plus CI with 'plan-do-study-act' (PDSA) cycles emphasizing self-reflection and group action, periodic learning sessions, and coaching from a CI mentor. Health workers collected data on standard HMIS out-patient registers. The qualitative evaluation (July 2015 to September 2016) included ethnographic observations at each health centre (over 12-14 weeks), in-depth interviews with health workers and stakeholders (n = 20), and focus group discussions with health workers (n = 6).

RESULTS

The results suggest that the intervention did facilitate improvement in data quality, but through unexpected mechanisms. The CI intervention was implemented as planned, but the PDSA cycles were driven largely by the CI mentor, not the health workers. In this context, characterized by a rigid hierarchy within the health system of limited culture of self-reflection and inadequate training and supervision, CI became an effective form of high-quality training with frequent supervisory visits. Health workers appeared motivated to improve data collection habits by their loyalty to the CI mentor and the potential for economic benefits, rather than a desire for self-improvement.

CONCLUSIONS

CI is a promising method of quality improvement and could have a positive impact on malaria surveillance data. However, successful scale-up of CI in similar settings may require deployment of highly skilled mentors. Further research, focusing on the effectiveness of 'real world' mentors using robust study designs, will be required to determine whether CI can be translated effectively and sustainably to low-resource settings.

Effectiveness of in-service training plus the collaborative improvement strategy on the quality of routine malaria surveillance data: results of a pilot study in Kayunga District, Uganda

BACKGROUND

Surveillance data are essential for malaria control, but quality is often poor. The aim of the study was to evaluate the effectiveness of the novel combination of training plus an innovative quality improvement method-collaborative improvement (CI)-on the quality of malaria surveillance data in Uganda.

METHODS

The intervention (training plus CI, or TCI), including brief in-service training and CI, was delivered in 5 health facilities (HFs) in Kayunga District from November 2015 to August 2016. HF teams monitored data quality, conducted plan-do-study-act cycles to test changes, attended periodic learning sessions, and received CI coaching. An independent evaluation was conducted to assess data completeness, accuracy, and timeliness. Using an interrupted time series design without a separate control group, data were abstracted from 156,707 outpatient department (OPD) records, laboratory registers, and aggregated monthly reports (MR) for 4 time periods: baseline-12 months, TCI scale-up-5 months; CI implementation-9 months; post-intervention-4 months. Monthly OPD register completeness was measured as the proportion of patient records with a malaria diagnosis with: (1) all data fields completed, and (2) all clinically-relevant fields completed. Accuracy was the relative difference between: (1) number of monthly malaria patients reported in OPD register versus MR, and (2) proportion of positive malaria tests reported in the laboratory register versus MR. Data were analysed with segmented linear regression modelling.

RESULTS

Data completeness increased substantially following TCI. Compared to baseline, all-field completeness increased by 60.1%-points (95% confidence interval [CI]: 46.9-73.2%) at mid-point, and clinically-relevant completeness increased by 61.6%-points (95% CI: 56.6-66.7%). A relative - 57.4%-point (95% confidence interval: - 105.5, - 9.3%) change, indicating an improvement in accuracy of malaria test positivity reporting, but no effect on data accuracy for monthly malaria patients, were observed. Cost per additional malaria patient, for whom complete clinically-relevant data were recorded in the OPD register, was $3.53 (95% confidence interval: $3.03, $4.15).

CONCLUSIONS

TCI improved malaria surveillance completeness considerably, with limited impact on accuracy. Although these results are promising, the intervention's effectiveness should be evaluated in more HFs, with longer follow-up, ideally in a randomized trial, before recommending CI for wide-scale use.

Assessment of molecular markers of anti-malarial drug resistance among children participating in a therapeutic efficacy study in western Kenya

BACKGROUND

Anti-malarial drug resistance remains a major threat to global malaria control efforts. In Africa, Plasmodium falciparum remains susceptible to artemisinin-based combination therapy (ACT), but the emergence of resistant parasites in multiple countries in Southeast Asia and concerns over emergence and/or spread of resistant parasites in Africa warrants continuous monitoring. The World Health Organization recommends that surveillance for molecular markers of resistance be included within therapeutic efficacy studies (TES). The current study assessed molecular markers associated with resistance to Artemether-lumefantrine (AL) and Dihydroartemisinin-piperaquine (DP) from samples collected from children aged 6-59 months enrolled in a TES conducted in Siaya County, western Kenya from 2016 to 2017.

METHODS

Three hundred and twenty-three samples collected pre-treatment (day-0) and 110 samples collected at the day of recurrent parasitaemia (up to day 42) were tested for the presence of drug resistance markers in the Pfk13 propeller domain, and the Pfmdr1 and Pfcrt genes by Sanger sequencing. Additionally, the Pfpm2 gene copy number was assessed by real-time polymerase chain reaction.

RESULTS

No mutations previously associated with artemisinin resistance were detected in the Pfk13 propeller region. However, other non-synonymous mutations in the Pfk13 propeller region were detected. The most common mutation found on day-0 and at day of recurrence in the Pfmdr1 multidrug resistance marker was at codon 184F. Very few mutations were found in the Pfcrt marker (< 5%). Within the DP arm, all recrudescent cases (8 sample pairs) that were tested for Pfpm2 gene copy number had a single gene copy. None of the associations between observed mutations and treatment outcomes were statistically significant.

CONCLUSION

The results indicate absence of Pfk13 mutations associated with parasite resistance to artemisinin in this area and a very high proportion of wild-type parasites for Pfcrt. Although the frequency of Pfmdr1 184F mutations was high in these samples, the association with treatment failure did not reach statistical significance. As the spread of artemisinin-resistant parasites remains a possibility, continued monitoring for molecular markers of ACT resistance is needed to complement clinical data to inform treatment policy in Kenya and other malaria-endemic regions.

The tolerability of single low dose primaquine in glucose-6-phosphate deficient and normal falciparum-infected Cambodians

Background

The WHO recommends single low-dose primaquine (SLDPQ, 0.25 mg/kg body weight) in falciparum-infected patients to block malaria transmission and contribute to eliminating multidrug resistant Plasmodium falciparum from the Greater Mekong Sub region (GMS). However, the anxiety regarding PQ-induced acute haemolytic anaemia in glucose-6-phosphate dehydrogenase deficiency (G6PDd) has hindered its use. Therefore, we assessed the tolerability of SLDPQ in Cambodia to inform national policy.

Methods

This open randomised trial of dihydroartemisinin-piperaquine (DHAPP) + SLDPQ vs. DHAPP alone recruited Cambodians aged ≥1 year with acute uncomplicated P. falciparum. Randomisation was 4:1 DHAPP+SLDPQ: DHAPP for G6PDd patients and 1:1 for G6PDn patients, according to the results of the qualitative fluorescent spot test. Definitive G6PD status was determined by genotyping. Day (D) 7 haemoglobin (Hb) concentration was the primary outcome measure.

Results

One hundred nine patients (88 males, 21 females), aged 4–76 years (median 23) were enrolled; 12 were G6PDd Viangchan (9 hemizygous males, 3 heterozygous females). Mean nadir Hb occurred on D7 [11.6 (range 6.4 ─ 15.6) g/dL] and was significantly lower (p = 0.040) in G6PDd (n = 9) vs. G6PDn (n = 46) DHAPP+SLDPQ recipients: 10.9 vs. 12.05 g/dL, Δ = -1.15 (95% CI: -2.24 ─ -0.05) g/dL. Three G6PDn patients had D7 Hb concentrations < 8 g/dL; D7-D0 Hbs were 6.4 ─ 6.9, 7.4 ─ 7.4, and 7.5 ─ 8.2 g/dL.

For all patients, mean (range) D7-D0 Hb decline was -1.45 (-4.8 ─ 2.4) g/dL, associated significantly with higher D0 Hb, higher D0 parasitaemia, and receiving DHAPP; G6PDd was not a factor. No patient required a blood transfusion.

Conclusions

DHAPP+SLDPQ was associated with modest Hb declines in G6PD Viangchan, a moderately severe variant. Our data augment growing evidence that SLDPQ in SE Asia is well tolerated and appears safe in G6PDd patients. Cambodia is now deploying SLDPQ and this should encourage other GMS countries to follow suit.

Trial registration

The clinicaltrials.gov reference number is NCT02434952.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-3862-1) contains supplementary material, which is available to authorized users.

Medical Male Circumcision Is Associated With Improvements in Pain During Intercourse and Sexual Satisfaction in Kenya

Background

Two cohort studies using data from randomized controlled trials in Africa offer the best evidence to date on the effects of voluntary medical male circumcision (VMMC) on male sexual function and satisfaction, suggesting no significant impairments in sexual function or satisfaction and some improvements in sexual function after male circumcision.

Aim

To assess the effects of VMMC on sexual function and satisfaction in a large population-based cohort of men circumcised as adults and uncircumcised controls in Kenya.

Methods

Sexual function and satisfaction of young (median age = 20 years) sexually active men (1,509 newly circumcised men and 1,524 age-matched uncircumcised controls after 5% loss to follow-up) were assessed at baseline and 6, 12, 18, and 24 months, with data collected in 2008 to 2012. Self-reported data on lack of sexual interest or pleasure, difficulty getting or maintaining erections, orgasm difficulties, premature ejaculation, pain during intercourse, and satisfaction with sexual intercourse were analyzed with mixed-effect models to detect differences between circumcised and uncircumcised men and changes over time.

Outcomes

Changes over time in sexual interest, desire and pleasure, erectile and ejaculatory function, and pain during intercourse (dyspareunia) in circumcised and uncircumcised men; group differences in time trends; satisfaction with sexual performance; and enjoyment of sex before and after circumcision.

Results

Sexual dysfunctions decreased in the two study groups from 17% to 54% at baseline to 11% to 44% at 24 months (P < .001), except dyspareunia, which decreased only in circumcised men (P < .001). Sexual satisfaction outcomes increased in the two study groups from 34% to 82% at baseline to 66% to 93% at 24 months (P < .001), with greater improvements in circumcised men (P < .001). On average, 97% of circumcised men were satisfied with sexual intercourse and 92% rated sex as more enjoyable or no different after circumcision compared with before circumcision.

Clinical Translation

Results are applicable to VMMC programs seeking to increase the acceptability of male circumcision as part of comprehensive HIV prevention.

Strengths and Limitations

Large-scale population-based longitudinal data restricted to sexually active individuals and adjusted for differences in baseline levels of outcomes and potential confounders are used. The questionnaire used, although not a standardized survey instrument, includes all major domains of male sexual function and satisfaction used in the most common standardized tools.

Conclusions

Results are consistent with large cohort studies of VMMC using data from randomized controlled trials and indicate that VMMC has no significant detrimental effect or might have beneficial effects on male sexual function and satisfaction for the great majority of men circumcised as adults.

Nordstrom MPC, Westercamp N, Jaoko W, et al. Medical Male Circumcision Is Associated With Improvements in Pain During Intercourse and Sexual Satisfaction in Kenya. J Sex Med 2017;14:601–612.

Risk compensation following male circumcision: results from a two-year prospective cohort study of recently circumcised and uncircumcised men in Nyanza Province, Kenya

We present the results of the first study of longitudinal change in HIV-associated risk behaviors in men before and after circumcision in the context of a population-level voluntary medical male circumcision (VMMC) program. The behaviors of 1,588 newly circumcised men and 1,598 age-matched uncircumcised controls were assessed at baseline, 6, 12, 18 and 24 months of follow-up. Despite the precipitous decline in perception of high HIV risk among circumcised men (30-14 vs. 24-21 % in controls) and increased sexual activity among the youngest participants (18-24 years; p-time < 0.0001, p-group = 0.96), all specific risk behaviors decreased over time similarly in both groups. The proportion of men reporting condom use at last sex increased for both groups, with a greater increase among circumcised men (30 vs. 6 %). We found no evidence of risk compensation in men following circumcision. Concerns about risk compensation should not impede the widespread scale-up of VMMC initiatives.

Measuring prevalence and correlates of concurrent sexual partnerships among young sexually active men in Kisumu, Kenya

Our objectives were to: (1) compare multiple measures of partnership concurrency, including the UNAIDS-recommended definition and (2) describe the prevalence and correlates of concurrent sexual partnerships among young Kenyan men. We analyzed 10,907 lifetime partnerships of 1,368 men ages 18-24 years enrolled in a randomized trial of male circumcision to reduce HIV-1 incidence in Kisumu. Partnership concurrency was determined by overlapping dates and examined over varying recall periods and assumptions. The lifetime prevalence of concurrency was 77 %. Sixty-one percent of all partnerships were concurrent and factors associated with concurrency differed by partner type. Point prevalence of concurrency at the time of the interview was consistently the highest and UNAIDS-recommended definition was the most conservative (25 vs. 18 % at baseline, respectively). Estimates of concurrency were influenced by methods for definition and measurement. Regardless of definition, concurrent partnerships are frequent in this population of young, sexually active men in high HIV prevalence Kisumu, Kenya.

Determinants of consistent condom use vary by partner type among young men in Kisumu, Kenya: a multi-level data analysis

To evaluate whether determinants of consistent condom use vary by partner type among young sexually active Kenyan men, we conducted a cross-sectional assessment of lifetime sexual histories from a sub-sample of men enrolled in a clinical trial of male circumcision. 7913 partnerships of 1370 men were analyzed. 262 men (19%) reported never, 1018 (74%) sometimes and 92 (7%) always using a condom with their partners. Condoms were always used in 2672 (34%) of the total relationships-212 (70%) of the relationships with sex workers, 1643 (40%) of the casual and 817 (23%) of the regular/marital relationships. Factors influencing condom use varied significantly by partner type, suggesting that HIV prevention messages promoting condom use with higher-risk partners have achieved a moderate level of acceptance. However, in populations of young, single men in generalized epidemic settings, interventions should promote consistent condom use in all sexual encounters, independently of partner type and characteristics.

Spatial distribution and cluster analysis of sexual risk behaviors reported by young men in Kisumu, Kenya

BACKGROUND

The well-established connection between HIV risk behavior and place of residence points to the importance of geographic clustering in the potential transmission of HIV and other sexually transmitted infections (STI).

METHODS

To investigate the geospatial distribution of prevalent sexually transmitted infections and sexual behaviors in a sample of 18-24 year-old sexually active men in urban and rural areas of Kisumu, Kenya, we mapped the residences of 649 men and conducted spatial cluster analysis. Spatial distribution of the study participants was assessed in terms of the demographic, behavioral, and sexual dysfunction variables, as well as laboratory diagnosed STIs. To test for the presence and location of clusters we used Kulldorff's spatial scan statistic as implemented in the Satscan program.

RESULTS

The results of this study suggest that sexual risk behaviors and STIs are evenly distributed in our sample throughout the Kisumu district. No behavioral or STI clusters were detected, except for condom use. Neither urban nor rural residence significantly impacted risk behavior or STI prevalence.

CONCLUSION

We found no association between place of residence and sexual risk behaviors in our sample. While our results can not be generalized to other populations, the study shows that geospatial analysis can be an important tool for investigating study sample characteristics; for evaluating HIV/STI risk factors; and for development and implementation of targeted HIV and STI control programs in specifically defined populations and in areas where the underlying population dynamic is poorly understood.

Acceptability of male circumcision for prevention of HIV/AIDS in sub-Saharan Africa: a review

Based on epidemiological, clinical and experimental evidence, male circumcision (MC) could have a significant impact on the HIV epidemic in selected areas. We reviewed studies of the acceptability of MC in sub-Saharan Africa to assess factors that will influence uptake of circumcision in traditionally non-circumcising populations. Thirteen studies from nine countries were identified. Across studies, the median proportion of uncircumcised men willing to become circumcised was 65% (range 29-87%). Sixty nine percent (47-79%) of women favored circumcision for their partners, and 71% (50-90%) of men and 81% (70-90%) of women were willing to circumcise their sons. Because the level of acceptability across the nine countries was quite consistent, additional acceptability studies that pose hypothetical questions to participants are unnecessary. We recommend pilot interventions making safe circumcision services available in conjunction with current HIV prevention strategies and evaluating the safety and acceptability of circumcision.