Human African trypanosomiasis in non-endemic countries.

Human African trypanosomiasis (HAT) or sleeping sickness is a parasitic disease, acquired by the bite of an infected tsetse fly. In non-endemic countries HAT is rare, and therefore the diagnosis may be delayed leading to potentially fatal consequences. In this article the clinical presentation, diagnosis and treatment of the two forms of HAT are outlined. Rhodesiense HAT is an acute illness that presents in tourists who have recently visited game parks in Eastern or Southern Africa, whereas Gambiense HAT has a more chronic clinical course, in individuals from West or Central Africa.

Factors associated with injection cessation, relapse and initiation in a community-based cohort of injection drug users in Chennai, India.

AIMS: To characterize factors associated with injection cessation, relapse and initiation. DESIGN: The Madras Injection Drug User and AIDS Cohort Study (MIDACS) is a prospective cohort of injection drug users (IDUs) recruited in 2005-06 with semi-annual follow-up to 2009. Discrete-time survival models were used to characterize predictors of time to first injection cessation and relapse. SETTING: Chennai, India. PARTICIPANTS: A total of 855 IDUs who reported injecting in the 6 months prior to baseline and had >1 follow-up visit. MEASUREMENTS: Cessation was defined as the first visit where no injection drug use was reported (prior 6 months) and relapse as the first visit where drug injection (prior 6 months) was reported after first cessation. FINDINGS: All participants were male; median age was 35 years. Over 3 years, 92.7% reported cessation [incidence rate (IR): 117 per 100 person-years]. Factors associated positively with cessation included daily injection and incarceration and factors associated negatively with cessation included marriage, alcohol and homelessness. Of those who reported cessation, 23.6% relapsed (IR: 19.7 per 100 person-years). Factors associated positively with relapse included any education, injection in the month prior to baseline, sex with a casual partner, non-injection drug use, incarceration and homelessness. Alcohol was associated negatively with relapse. The primary reasons for cessation were medical conditions (37%) and family pressure (22%). The majority initiated with non-injection drugs, transitioning to injection after a median 4 years. CONCLUSIONS: Injection drug users in southern India demonstrate a high rate of injection cessation over 3 years, but relapse is not uncommon. Compensatory increases in alcohol use indicate that cessation of injection does not mean cessation of all substance use. Family pressure, concerns about general health, fear of human immunodeficiency virus infection and a history of non-injection drug use are important correlates of cessation.

Determinants of HIV-1 transmission in men who have sex with men: a combined clinical, epidemiological and phylogenetic approach.

OBJECTIVES: To identify biological factors associated with HIV transmission in men who have sex with men (MSM). DESIGN: A longitudinal phylogenetic analysis of HIV-1 from an MSM cohort, incorporating clinical and epidemiological data. METHODS: Potential individuals were HIV-infected MSM attending a sexual health clinic between 2000 and 2006. Individuals were classified such that they could move from recent to chronic infection categories. HIV-1pol gene sequences were obtained from plasma virus or proviral DNA and clusters estimated by maximum likelihood and conservative genetic distance differences. The single most likely transmitter generating each recent infection was ascertained and risk factors around time of likely transmission explored using Poisson regression modelling. RESULTS: Out of 1144 HIV-infected MSM, pol sequence data were obtained for 859 (75%); 159 out of 859 (19%) were recently HIV infected at diagnosis. A single most likely transmitter was identified for 41 out of 159 (26%), of which 11 were recently infected (27%) and 30 chronically infected. Factors associated with transmission in multivariable analysis were: younger age {rate ratio per 5 years older 0.68 [95% confidence interval (CI) 0.54-0.86], P=0.0009}, higher viral load [rate ratio per log higher 1.61 (95% CI 1.15-2.25), P=0.005], recent infection [rate ratio 3.88 (95% CI 1.76-8.55), P=0.0008] and recent sexually transmitted disease [rate ratio 5.32 (95% CI 2.51-11.29), P=0.0001]. HAART was highly protective in a univariable model, RR 0.14 (95% CI 0.07-0.27, P=0.0001). CONCLUSION: Onward transmission of HIV among MSM is significantly associated with recent infection, sexually transmitted diseases and higher viral load, and reduced by effective HAART. The majority of new infections appear to occur from individuals whose infection was undiagnosed at the time of transmission.