HIV epidemic trend and antiretroviral treatment need in Karonga District, Malawi

Abstract

We describe the development of the HIV epidemic in Karonga District, Malawi over 22 years using data from population surveys and community samples. These data are used to estimate the trend in HIV prevalence, incidence and need for antiretroviral treatment (ART) using a simple mathematical model. HIV prevalence rose quickly in the late 1980s and early 1990s, stabilizing at around 12% in the mid-1990s. Estimated annual HIV incidence rose quickly, peaking in the early 1990s at 2.2% among males and 3.1% among females, and then levelled off at 1.3% among males and 1.1% among females by the late 1990s. Assuming a 2-year eligibility period, both our model and the UNAIDS models predicted 2.1% of adults were in need of ART in 2005. This prediction was sensitive to the assumed eligibility period, ranging from 1.6% to 2.6% if the eligibility period was instead assumed to be 1.5 or 2.5 years, respectively.

Fig. 1

Top panels: Observed and estimated trend in HIV prevalence (%) among individuals in the community aged ⩾15 years, by sex and year (%). Bottom panels: Estimated annual HIV incidence in the community among individuals aged ⩾15 years, by sex and year (% per year). Two models were used in which the trend in HIV incidence was or was not permitted to decrease from its peak. Bars show 95% confidence intervals around data-point estimates.

Fig. 2

Observed and estimated trend in male and female HIV prevalence among individuals in the community aged ⩾15 years, by age, sex and year. Two models were used in which the trend in HIV incidence was or was not permitted to decrease from its peak. Bars show 95% confidence interval around data-point estimate. □, Data;, model (no decline in HIV incidence); ■, model (decline in HIV incidence).

Fig. 3

Estimated annual HIV incidence among susceptible individuals in the community aged ⩾15 years, by age, sex and year (% per year). Two models were used in which the trend in HIV incidence was not permitted (top panels) or was permitted (bottom panels) to decrease from its peak. Lines for 1996 and 2001 were coincident for the no-decrease scenario.

Fig. 4

Estimated prevalence by time since infection (top panels) and time to death (bottom panels) among individuals in the community aged ⩾15 years, by sex and year (%). The model permitted HIV incidence to decrease from its peak.

Fig. 5

Estimated prevalence by time to death from AIDS among individuals in the community aged ⩾15 years in 2005, by age and sex (%). The model permitted HIV incidence to decrease from its peak.