People newly diagnosed with HIV/STIs often have individuals with undiagnosed HIV in their social network

Michael Carter
Published: 30 December 2013

Asking people who are newly diagnosed with HIV or a sexually transmitted infection (STI) to recruit contacts in their social network for HIV/STI screening is an effective way of detecting previously undiagnosed infections, investigators report in the online edition of the Journal of Acquired Immune Deficiency Syndromes. The study was conducted in Malawi. Patients were asked to recruit up to five individuals from their social or sexual network for testing.

“Asking STI patients to recruit their social contacts was a feasible, effective and efficient way of diagnosing new HIV cases in a generalized epidemic,” write the authors. “To identify one new case of HIV infection only 8-10 contacts of clinic seeds needed to be tested for HIV, much better efficacy than random testing in the population.”

Approximately 11% of adults in Malawi are HIV positive. But up to a third of HIV cases are undiagnosed. Reducing the proportion of undiagnosed infections is a public health priority. An international team of investigators wanted to see if social network recruitment by people newly diagnosed with HIV/STIs was an efficient and effective way of reaching people with previously undiagnosed infections.

They therefore designed a study involving two groups of patients – each numbering 45 individuals – who accessed care at the STI clinic at Kamuzu Central Hospital in Lilongwe, Malawi between 2010 and 2012. The first group comprised people newly diagnosed with HIV; the second comprised people diagnosed with an STI but not HIV. A control arm consisted of 45 individuals without HIV or an STI were also recruited from the general, local population.

All the participants were aged between 18 and 45 years. They were asked to recruit up to five individuals in their social or sexual network for HIV/STI screening.

Almost two-thirds of participants were women and the mean age was 27 years.

The participants recruited a total of 244 contacts. Over two-thirds (69%) of individuals recruited from the community recruited at least one contact, compared to 53% of STI patients and 47% of HIV-positive participants.

Almost two-thirds (62%) of contacts were friends or neighbours of the recruiting individual, 18% were family members, 11% were sexual contacts (primarily spouses) and 8% had another relationship.

Most of the contacts (64%) were female and their mean age was 28 years.

HIV prevalence was three times higher among the contacts of the HIV-positive patients than the contacts of the community controls (31 vs 11%).

The contacts of the HIV-positive patients and patients with STIs were more likely to have an STI than the contacts of the community controls (29 vs 19 vs 9%).

A total of 20 patients were newly diagnosed with HIV through the study. Seven of these individuals were recruited by patients with HIV, seven by STI patients and six by community controls.

In order to identify one new case of HIV it was necessary to screen eight contacts of the HIV patients; ten contacts of the STI patients and 18 contacts of the community controls.

To identify one new STI, six contacts of patients with HIV, four contacts of STI patients and eleven contacts of community controls required screening.

Identification of one new case of HIV or a new STI required the screening of four contacts of patients with HIV, three contacts of STI patients and seven contacts of the controls.

“High risk persons tend to associate with other persons who engage in similar high risk activities,” write the authors. “Even in the context of a generalized HIV epidemic, STI and HIV risk was not evenly distributed, but rather, clustered in social networks.”

The investigators believe their findings have implications for HIV screening and testing strategies. “Our findings reflect a novel strategy for addressing a pressing public health need: identifying undiagnosed, hard-to-reach cases of HIV infection,” they conclude. “We demonstrated that asking STI patients to recruit their social contacts was a feasible, effective, and efficient way of identifying this population. These observations support social contact recruitment extending the reach of the healthcare screening system. Such an approach could become a powerful way of identifying HIV in hard-to-reach populations earlier.”


Rosenberg NE et al. STI patients are effective recruiters of undiagnosed cases of HIV: results of a social contact recruitment study in Malawi. J Acquir Immune Defic Syndr, online edition. DOI: 10.1097/000000000000066, 2013.

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