BOSTON – Nearly 1 year after 11 new HIV infections were diagnosed in Scott County, Ind., a region that had an incidence of fewer than 1 HIV infection per year over the previous decade, 188 new HIV infections have now been diagnosed, and more than 90% of the cases were coinfected with hepatitis C (HCV), according to Dr. John T. Brooks of the Centers for Disease Control and Prevention.
Lessons from the outbreak, he said, include the inescapable fact that the United States is experiencing an expanding epidemic of heroin use that is driving an increase in injection drug use, putting many more U.S. residents at risk for the spread of HIV and HCV infection.
The response to the outbreak “required a large and extremely intensive collaboration of local, state, and federal public health resources in close partnership with community members, and like all outbreak investigations, there are two goals: First, establish the extent of the outbreak, and then institute prevention and control measures,” Dr. Brooks reported at a plenary session at the Conference on Retroviruses and Opportunistic Infections.
Once the cases were detected and confirmed, the health authorities went into action, deploying emergency command at the state level, similar to that deployed during a weather disaster, with a team of 35 disease intervention specialists and other public health workers from 14 states and the District of Columbia who went door to door, testing as many people as possible to find HIV infections, and tracing contacts to determine where additional, undiagnosed cases might be.
“The pattern of how we approached this outbreak is very much how you might approach tuberculosis, where you first detect that there’s a disease and confirm the diagnosis, you deploy an intervention to treat – sort of induction therapy – and once it’s under control you switch to consolidation therapy to keep the disease at bay, and then over time you might scan the person or follow up to see if the disease is recurring. The difference here is that we’re doing it on a population level,” said Dr. Brooks of the CDC’s division of HIV/AIDS prevention.
Astute observer spotted trend
The outbreak came to the attention of public health authorities when a “very, very astute” disease intervention specialist working in the county health department recognized that there were 11 new infections related to one another in Scott County, with the epicenter in the town of Austin.
Early in the outbreak, investigators determined that the HIV and HCV transmissions were occurring in a dense network of persons who inject drugs, mostly the opioid analgesic oxymorphone, but also heroin, methamphetamine, and cocaine. “During interviews, it was evident that 96% of the people had injected in the past 12 months, and that oxymorphone was the preferred drug used by 92%,” Dr. Brooks said.
Oxymorphone is available in generic and branded formulations. Although the brand name version (Opana and Opana ER) has a coating intended to prevent crushing the pills and dissolving the drug for the purpose of injection, “addiction can make you very creative, and the residents of this town had figured how to get around that,” Dr. Brooks said.
The outbreak was multigenerational, and it was not uncommon to find a household with three generations of drug abusers – grandparent, parents, and children – who injected drugs between 4 and 15 times each day, with one to as many as six needle-sharing partners per injection event, and sharing of injection equipment. Information was available on 181 of the 188 HIV-infected cases. The median age was 34 years (interquartile range, 28-42), 58% were male, 99% were non-Hispanic whites, and 96% had injected drugs within the past 12 months.
The investigators established HIV testing both in the Scott County jail and in detention centers in surrounding counties in a sentinel system to determine whether the outbreak might have spread beyond the county line. The disease intervention specialists collected intravenous blood samples and performed point-of-care rapid testing for later confirmation, and for testing for acute HIV and HCV infection.
The workers also provided county residents with disease prevention educational materials and directed them to services as required, including treatment and antiretroviral therapy, and/or addition and harm reduction services and preexposure prophylaxis, if appropriate.
Major logistical challenges for responders included the fact that very few affected individuals were either employed or insured, and most lacked the necessary documents to enroll in state-supported care Medicaid expansion, recently adopted by Indiana as part of the Affordable Care Act.