Case study Cabo Verde: Simulation offers policy Rx for curbing HIV

April 08, 2015

When a whole country's public health is at stake, making the wrong policy choices can cost lives and money. That's why researchers have worked to develop computer simulations of epidemics that can model individual behaviors and interactions to predict the spread of disease and the efficacy of interventions.

The results of a new study suggest that Cabo Verde could all but stamp out HIV if it can accelerate four efforts already underway across the tiny African archipelago. Moreover, the model predicts that annual new cases could fall below the key threshold of 10 per 10,000 residents even if the country just focuses the additional efforts on female sex workers and drug users, two groups with unusually high prevalence of infection.

"You don't have to scale up everything," said Filipe Monteiro, lead author of the study in the International Journal of Public Health and a postdoctoral scholar at Brown University. "You can just prioritize the specific groups."

The modeled interventions were extending and optimizing early HIV treatment, expanding HIV testing, increasing condom distribution, and providing more substance abuse treatment. Monteiro, a native of the country, wanted to see whether significant expansions of those programs over the decade between 2011 and 2021 could bring new cases below the 10 per 10,000 threshold that some global health experts call the "HIV elimination phase."

To make those predictions he employed the computer model co-developed by his advisor, Brandon Marshall, assistant professor of epidemiology in the Brown University School of Public Health. Their team's implementation included 305,000 individually behaving "agents," enough to represent every Cabo Verdean adult.

"Here we were able to simulate the whole country," Monteiro said.

In the model, "agents" (representing real people) do what's relevant to the epidemic such as have sex with varying numbers of partners (sometimes protected and sometimes not), use drugs, start and stop medicine, get tested, transmit the virus, and sometimes die. All the parameters, such as drug use, frequency of sex, response to HIV medications and so on, are based in real data. For example, the percentage of people engaged in drug use and women engaged in prostitution are based on Cabo Verde's real rates, as are the prevalence HIV infection in those populations and among adults nationwide. The one major missing cohort, men who have sex with men, had to be left out of the model because there is not yet reliable HIV and population data for them.

To determine the efficacy of the interventions, Monteiro ran the model 100 times each for each of the following scenarios, both for the whole population and just among drug users and female sex workers: continuing the status quo of current interventions, doubling HIV testing, increasing condom distribution by 33 percent, doubling substance abuse treatment, doubling antiretroviral treatment, and doing all these interventions at the same time.

The combination approach lowered new cases the most compared to the status quo, both when the interventions were applied population wide and when they were applied just to the at-risk groups. In the whole population scenarios, for example, the combination of all four interventions reduced new cases in 2021 from 23.8 per 10,000 under the status quo to 6.7 per 10,000 among female sex workers who use drugs, and from 5.1 per 10,000 among general residents (non-drug using, non-prostitutes) to 1.4 new cases per 10,000.

Meanwhile, focusing the combination approach only on at-risk groups reduced new cases among drug-using sex workers to 7.3 per 10,000 and among general population members to 3.4 per 10,000.

The research also highlighted what would likely be the weakest approach: either solely scaling up HIV testing, or only expanding substance abuse treatment. For example, the effect of solely increasing HIV testing, was weaker, reducing new cases among drug using sex workers to 17.6 per 10,000, and cases among general population members to 4.5 per 10,000.

Monteiro said he is optimistic that Cabo Verde can move forward with these interventions in real life, rather than in a laptop. Although key data, such as for men who have sex with men, are still needed, he and his co-authors, including Maria de Lourdes Monteiro of the Cabo Verde Ministry of Health, wrote that their findings provide a clear policy prescription.

"We recommend a combination prevention strategy, particularly for populations most at-risk, to decrease and eventually eliminate HIV transmission in Cabo Verde and other settings characterized by concentrated, overlapping HIV epidemics in key affected groups," they wrote.
-end-
The paper's other authors are Dr. Tim Flanigan of Brown University and The Miriam Hospital, Sandro Galea of Boston University, and Samuel Friedman of the National Development and Research Institutes.

The National Institute of Health funded the study (R01-DA013336, T32-DA13911, P30-AI042853, T32-DA013911).

Brown University

Related HIV Articles from Brightsurf:

BEAT-HIV Delaney collaboratory issues recommendations measuring persistent HIV reservoirs
Spearheaded by Wistar scientists, top worldwide HIV researchers from the BEAT-HIV Martin Delaney Collaboratory to Cure HIV-1 Infection by Combination Immunotherapy (BEAT-HIV Collaboratory) compiled the first comprehensive set of recommendations on how to best measure the size of persistent HIV reservoirs during cure-directed clinical studies.

The Lancet HIV: Study suggests a second patient has been cured of HIV
A study of the second HIV patient to undergo successful stem cell transplantation from donors with a HIV-resistant gene, finds that there was no active viral infection in the patient's blood 30 months after they stopped anti-retroviral therapy, according to a case report published in The Lancet HIV journal and presented at CROI (Conference on Retroviruses and Opportunistic Infections).

Children with HIV score below HIV-negative peers in cognitive, motor function tests
Children who acquired HIV in utero or during birth or breastfeeding did not perform as well as their peers who do not have HIV on tests measuring cognitive ability, motor function and attention, according to a report published online today in Clinical Infectious Diseases.

Efforts to end the HIV epidemic must not ignore people already living with HIV
Efforts to prevent new HIV transmissions in the US must be accompanied by addressing HIV-associated comorbidities to improve the health of people already living with HIV, NIH experts assert in the third of a series of JAMA commentaries.

The Lancet HIV: Severe anti-LGBT legislations associated with lower testing and awareness of HIV in African countries
This first systematic review to investigate HIV testing, treatment and viral suppression in men who have sex with men in Africa finds that among the most recent studies (conducted after 2011) only half of men have been tested for HIV in the past 12 months.

The Lancet HIV: Tenfold increase in number of adolescents on HIV treatment in South Africa since 2010, but many still untreated
A new study of more than 700,000 one to 19-year olds being treated for HIV infection suggests a ten-fold increase in the number of adolescents aged 15 to 19 receiving HIV treatment in South Africa, according to results published in The Lancet HIV journal.

Starting HIV treatment in ERs may be key to ending HIV spread worldwide
In a follow-up study conducted in South Africa, Johns Hopkins Medicine researchers say they have evidence that hospital emergency departments (EDs) worldwide may be key strategic settings for curbing the spread of HIV infections in hard-to-reach populations if the EDs jump-start treatment and case management as well as diagnosis of the disease.

NIH HIV experts prioritize research to achieve sustained ART-free HIV remission
Achieving sustained remission of HIV without life-long antiretroviral therapy (ART) is a top HIV research priority, according to a new commentary in JAMA by experts at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.

The Lancet HIV: PrEP implementation is associated with a rapid decline in new HIV infections
Study from Australia is the first to evaluate a population-level roll-out of pre-exposure prophylaxis (PrEP) in men who have sex with men.

Researchers date 'hibernating' HIV strains, advancing BC's leadership in HIV cure research
Researchers have developed a novel way for dating 'hibernating' HIV strains, in an advancement for HIV cure research.

Read More: HIV News and HIV Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.