HIV Incidence and Spatial Clustering in Mozambique

A sobering paper from Manhiça, Mozambique just came out. I have not spent significant time in Manhiça but have passed through before (often buying cashews from roadside vendors). Manhiça is a small town on a highway a couple of hours north of Maputo. It has extremely high HIV prevalence (almost 40% in adults). The Centro de Investigação em Saúde de Manhiça (CISM) is a research center associated with the Spanish government. CISM conducts a number of research studies on malaria and HIV and since 1996 has been running a demographic surveillance system. In this study, the researchers estimated overall HIV incidence to be 3.6 new infections per 100 person-years at risk. They used a Spatial Scan Statistics program to identify areas with disproportionate excess in HIV prevalence. They found a cluster of high HIV prevalence near a sugar mill in Manhiça and argue that it might be a “hot spot” related to migration. However, we do not know that HIV infections actually occurred in this geographic area.

To stop HIV transmission, we must reduce HIV incidence (i.e. new HIV infections). The most effective method of doing that is getting everyone on antiretroviral therapy with an undetectable HIV viral load.  Once the viral load is undetectable, HIV transmission virtually ceases, as we learned from HPTN-052. The question is how to target ART to people most likely to transmit the HIV virus, and make sure all people have an undetectable viral load, all in an era of dwindling financial resources. Even in the United States, this is a complex undertaking, as Jon Cohen recently described in Science.

My question for the Manhiça researchers is ART coverage. Many people have been working extremely hard in Mozambique to increase access to lifesaving ART. The authors state that participants in their study with an HIV positive result were offered medical follow up at the Manhiça outpatient clinic, which included CD4 counts, clinical management and provision of ART according to national guidelines. However, we do not know what percentage of HIV positive individuals actually got on ART and achieved an undetectable viral load. As far as I know, viral load is rarely done in Manhiça. Achieving virologic suppression across a population is an enormous task (we certainly haven’t been able to do it in the United States). Manhiça has more resources than most districts in rural Mozambique but expanding access to ART remains a major challenge. Yet this is an issue well beyond drugs and money. As we saw in West Africa with Ebola, it has to do with human resources, training, and community partnerships. It would be interesting to see a qualitative study from people in Manhiça living with HIV, health workers, and community members regarding those issues.

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