Estimating HIV incidence from case-report data: method and an application in Colombia.

OBJECTIVE: Quantifying HIV incidence is essential for tracking epidemics but doing this in concentrated epidemic can be a particular challenge because of limited consistent high-quality data about the size, behaviour and prevalence of HIV among key populations. Here, we examine a method for estimating HIV incidence from routinely collected case-reporting data. METHODS: A flexible model of HIV infection, diagnosis and survival is constructed and fit to time-series data on the number of reported cases in a Bayesian framework. The time trend in the hazard of infection is specified by a penalized B-spline. We examine the performance of the model by applying it to synthetic data and determining whether the method is capable of recovering the input incidence trend. We then apply the method to real data from Colombia and compare our estimates of incidence with those that have been derived using alternative methods. RESULTS: The method can feasibly be applied and it successfully recovered a range of incidence trajectories in synthetic data experiments. However, estimates for incidence in the recent past are highly uncertain. When applied to data from Colombia, a credible trajectory of incidence is generated which indicates a much lower historic level of HIV incidence than has previously been estimated using other methods. CONCLUSION: It is feasible, though not satisfactory, to estimate incidence using case-report data in settings with good data availability. Future work should examine the impact on missing or biased data, the utility of alternative formulations of flexible functions specifying incidence trends, and the benefit of also including data on deaths and programme indicators such as the numbers receiving antiretroviral therapy.

HIV transmission patterns among The Netherlands, Suriname, and The Netherlands Antilles: a molecular epidemiological study.

We aimed to study patterns of HIV transmission among Suriname, The Netherlands Antilles, and The Netherlands. Fragments of env, gag, and pol genes of 55 HIV-infected Surinamese, Antillean, and Dutch heterosexuals living in The Netherlands and 72 HIV-infected heterosexuals living in Suriname and the Antilles were amplified and sequenced. We included 145 pol sequences of HIV-infected Surinamese, Antillean, and Dutch heterosexuals living in The Netherlands from an observational cohort. All sequences were phylogenetically analyzed by neighbor-joining. Additionally, HIV-1 mobility among ethnic groups was estimated. A phylogenetic tree of all pol sequences showed two Surinamese and three Antillean clusters of related strains, but no clustering between ethnic groups. Clusters included sequences of individuals living in Suriname and the Antilles as well as those who have migrated to The Netherlands. Similar clustering patterns were observed in env and gag. Analysis of HIV mobility among ethnic groups showed significantly lower migration between groups than expected under the hypothesis of panmixis, apart from higher HIV migration between Antilleans in The Netherlands and all other groups. Our study shows that HIV transmission mainly occurs within the ethnic group. This suggests that cultural factors could have a larger impact on HIV mobility than geographic distance.

The efficacy of combination antiretroviral therapy in HIV type 1-infected patients treated in Curaçao compared with Antillean, Surinam, and Dutch HIV type 1-infected patients treated in The Netherlands.

We compared the efficacy of combination antiretroviral therapy (cART) of Antillean HIV-1-infected patients treated on the Caribbean island of Curaçao (CUR-AN) with Antillean (NL-AN), Surinam (NL-SUR), and Dutch (NL-NL) patients treated in The Netherlands. In total 2118 therapy-naive patients who started cART between January 2005 and August 2008 were included in the comparison. The CUR-AN patients initiated cART at a median CD4 cell count of 141 cells/mm(3) and 63% had counts below 200 cells/mm(3). Within 12 months of the start of cART 76% of the CUR-AN patients achieved viral suppression, defined as HIV-1 RNA plasma levels below 80 copies/ml. The percentage achieving viral suppression was higher in patients treated in The Netherlands (NL-AN = 87%, NL-SUR = 93%, and NL-NL = 96%). Lost to follow-up after 30 months of cART was 10% among CUR-AN patients and was higher than observed among patients treated in The Netherlands (NL-AN = 8%, NL-SUR = 3%, and NL-NL = 2%). A similar pattern was found for progression to AIDS and death (10% of CUR-AN vs. 5%, 6%, and 7% of NL-AN, NL-SUR, and NL-NL patients, respectively). Late start of cART and limited viral suppression after the start of cART determine the higher rate of disease progression to AIDS and death among Antillean patients treated in Curaçao. The high percentage of lost to follow-up may result in an underestimation of AIDS and AIDS-related death among HIV-1-infected Antilleans treated in Curaçao.