High HIV risk in a cohort of male sex workers from Nairobi, Kenya

OBJECTIVES

Men who have sex with men (MSM) are at high risk of HIV-1 acquisition and transmission, yet there remains limited data in the African context, and for men who sell sex to men (MSM SW) in particular.

METHODS

We enrolled 507 male sex workers in a Nairobi-based prospective cohort study during 2009-2012. All participants were offered HIV/STI screening, counselling and completed a baseline questionnaire.

RESULTS

Baseline HIV prevalence was 40.0% (95% CI 35.8% to 44.3%). Prevalent HIV infection was associated with age, less postsecondary education, marijuana use, fewer female partners and lower rates of prior HIV testing. Most participants (73%) reported at least two of insertive anal, receptive anal and insertive vaginal sex in the past 3 months. Vaginal sex was reported by 37% of participants, and exclusive MSM status was associated with higher HIV rates. Condom use was infrequent, with approximately one-third reporting 100% condom use during anal sex. HIV incidence was 10.9 per 100 person-years (95% CI 7.4 to 15.6). Predictors of HIV risk included history of urethral discharge (aHR 0.29, 95% CI 0.08 to 0.98, p=0.046), condom use during receptive anal sex (aHR 0.05, 95% CI 0.01 to 0.41, p=0.006) and frequency of sex with male partners (aHR 1.33/sex act, 95% CI 1.01 to 1.75, p=0.04).

CONCLUSIONS

HIV prevalence and incidence were extremely high in Nairobi MSM SW; a combination of interventions including increasing condom use, pre-exposure prophylaxis and access to effective treatment is urgently needed to decrease HIV transmission in this key population.

Using diaries to measure parameters of transactional sex: an example from the Trans-Africa highway in Kenya

Conventional methods of elicitation have severe limitations where sensitive information is being sought, resulting from both self-disclosure and recall bias. The use of diaries largely circumvents both of these problems. Four hundred and three female sex workers based on a section of the Trans-Africa Highway in Kenya completed standard diaries for consecutive 28-day periods. Variables measured included numbers and types of different clients, condom use, occupation of client, movement patterns and days of menses. Mean numbers of sexual partners, liaisons and sex acts and inter-relationships between the variables measured are analysed. The study affirms the value of diaries as an elicitation method for studying transactional sex in a resource-poor setting. Usable diaries were received from 70% of those who had agreed to participate in the study. The diaries yield detailed quantitative data that describe the characteristics and dynamics of transactional sex on a major highway in Africa and provide information that may be used to estimate HIV transmission rates.

In vitro host range studies with a new baculovirus isolate from the diamondback moth Plutella xylostella (L.) (Plutellidae: Lepidoptera)

The in vitro host range of a newly isolated baculovirus from the diamondback moth Plutella xylostella was tested against six lepidopteran cell liness. Two baculoviruses with wide host ranges from the alfalfa looper Autographa californica (A. californica multiple nucleopolvhedrovirus, AcMNPV) and the celery looper Anagrapha falcifera (AfMNPV) were also included in this study for comparative purposes. PxMNPV replicated in all six cell lines and produced occlusion bodies, with HV-AM1 and TN-CL1 cells producing the highest viral titers and greatest number of occlusion bodies. There was no significant replication of AcMNPV and AfMNPV in the HZ-FB33 cell line and thus no production of occlusion bodies. The restriction endonuclease profiles of the three baculoviruses showed similarities but could be readily distinguished from each other. Either HV-AM1 or TN-CL1 would be suitable cell lines for the in vitro production of PxMNPV.

Infectivity studies of a new baculovirus isolate for the control of the diamondback moth (Plutellidae: Lepidoptera)

This study describes a new baculovirus isolate recovered from infected larvae of the diamondback moth, Plutella xylostella (L.), and identified as a multiple nucleopolyhedrovirus (MNPV). The plaque purified isolate designated as PxMNPVCL3 was found to be pathogenic to P. xylostella, Heliothis virescens (F.), Trichoplusia ni (Hübner), H. subflexa (Guenée), Helicoverpa zea (Boddie), Spodoptera exigua (Hübner), and S. frugiperda (J. E. Smith) larvae in decreasing order of susceptibility. The LC50 for diamondback moth, the most susceptible, was 6 occlusion bodies (OB)/cm2, whereas the most resistant species, namely S. frugiperda, was 577 OB/cm2. PxMNPVCL3 was more pathogenic to diamondback moth by 3-4 log cycles as compared with 2 broad-spectrum baculoviruses, namely Autographa california (alfalfa looper) MNPV and Anagrapha falcifera (celery looper) MNPV. The 3 baculoviruses were compared with each other and characterized by restriction endonuclease (REN) analysis, hybridization, and neutralization tests. Fragmentation profiles generated by REN showed that the 3 baculoviruses shared some fragments in common. Hybridization studies employing digoxigenin labeled PxMNPVCL3 DNA as a probe revealed the close but distinct relationship of these 3 viruses. Neutralization tests confirmed the hybridization studies, namely that the 3 viruses although genetically similar are distinguishable from each other.