HIV prevalence and incidence fall in Kenya

HIV incidence and prevalence are declining in Kenya, investigators report in the online edition of the Journal of Acquired Immune Deficiency Syndromes. They compared results of large cross-sectional surveillance surveys conducted in 2007 and again in 2012. HIV prevalence fell from 7.2 to 5.6% and the incidence rate from 0.7 to 0.4%. The authors attribute the deceleration of the HIV epidemic in Kenya to improvements in linkage to care and the roll-out of antiretroviral therapy.

“Our data confirm a significant decline in HIV prevalence,” comment the authors. “Declining incidence in Kenya coincides with similar declines in new HIV infections reported by at least 26 countries in Africa, Asia, and the Caribbean between 2001 and 2012.”

Kenya has the fourth-largest HIV epidemic in the world: in 2012, out of a population of 40 million, an estimated 1.6 million individuals were living with HIV and there were approximately 98,000 new infections.

Strategies to control the country’s epidemic are reliant upon reliable surveillance data.

In 2007, the Kenya AIDS Indicator Survey (KAIS) showed that HIV prevalence in adults was over 7% and the adult HIV incidence rate was 0.7%.

KAIS was repeated in 2012 with the aim of establishing revised prevalence and incidence rates and also the factors associated with undiagnosed HIV infection.

KAIS 2012 was a cross-section household survey of individuals aged between 18 months and 64 years living in nine Kenyan regions. The investigators restricted their present analysis to adolescents and adults aged between 15 and 64 years.

Study participants answered questionnaires concerning their demographics and HIV risk behaviour. Blood samples were obtained and tested for HIV.

A total of 11,626 individuals were included in the investigators’ analyses. Just over half (51%) were women and the median age was 33 years. The majority (64%) resided in rural areas. Most (85%) were sexually experienced and 72% reported sex in the previous twelve months. A fifth of men and 3% of women reported two or more sexual partners in the past year. Anal sex was reported by 2% of men and 2% of women. Symptoms of a sexually transmitted infection in the previous twelve months were reported by 3% of men and 9% of women. Most men (91%) were circumcised and 71% of women said their male partner was circumcised. The majority of participants (85%) reported a low self-perceived risk of HIV infection.

HIV prevalence was 5.6% and HIV incidence was 0.4% – an annual HIV transmission rate of 7.1 per 100 HIV-positive people. Women had significantly higher HIV prevalence than men (6.9 vs 4.4%; p < 0.001). Prevalence increased with age, peaking in the 35 to 39 age group for women (12.3%) and 45 to 54 age group for men (7.2%).

Comparison with the KAIS 2007 data showed that overall HIV prevalence had fallen significantly from 7.2 to 5.6% in 2012 (p = 0.002). Significant decreases were seen in both women (2007 = 8.5% vs 2012 = 6.9%; p = 0.006) and men (2007 = 5.5% vs 2007 = 4.4%; p = 0.031).

Analysis of the factors associated with undiagnosed HIV infection (vs HIV-negative status) was restricted to the approximately 10,000 individuals who reported ever having sex.

Overall HIV prevalence was 6.3% and 52% of these infections were undiagnosed.

Factors associated with undiagnosed HIV infection in men were widowhood (AOR = 8.1; 95% CI, 1.9-34.6; p = 0.005) and condom use (AOR = 3.3; 95% CI, 1.8-6.2; p < 0.001). Circumcision was associated with a lower risk of undiagnosed HIV infection (AOR = 0.3; 95% CI, 0.1-0.5; p < 0.001).

Risk factors for undiagnosed HIV infection among women included being aged 35 to 39 years (AOR = 4.5; 95% CI, 1.1-18.3; p = 0.037), being separated or divorced (AOR = 2.3; 95% CI, 1.1-5.0; p = 0.033), condom use (AOR = 2.3%; 95% CI, 1.2-4.2; p< 0.09) and reporting four or more lifetime sexual partners (AOR = 1.9; 95% CI, 1.1-3.4; p = 0.026).

Why the reported falls in prevalence and incidence? The investigators believe increased access to HIV therapy has an important role.

They explain: “Over the past five years, Kenya has experienced substantial progress in linking HIV-infected persons into care and placing those who require antiretroviral therapy (ART) on treatment. Increased coverage of ART and high levels of viral suppression on ART have led to reductions in HIV mortality and transmission on a population level.”

But the authors are concerned that over half of HIV infections are still undiagnosed, and believe this is “a major barrier to achieving greater reductions in HIV transmission.”