In a small, rural town in Southern Indiana, a public health crisis emerges.  In a community that normally sees fewer than five new HIV diagnoses a year, more than a hundred new cases are diagnosed and almost all are coinfected with hepatitis C virus (HCV).

How was this outbreak discovered, and what caused this widespread transmission? Indiana state and local public health officials – supported by CDC – set out to answers these questions and help stop the spread of HIV and HCV in this community.

The Outbreak

In January 2015, Indiana disease intervention specialists noticed that 11 new HIV diagnoses were all linked to the same rural community.  This spike in HIV diagnoses in an area never before considered high-risk for the spread of HIV, launched a larger investigation into the cause and impact of these related cases.

The investigation began by investigating the 11 newly diagnosed cases. This process involved talking to newly diagnosed individuals about their health and sexual behaviors, as well as past drug use. In the United States, HIV is spread mainly by having sex or sharing injection drug equipment such as needles with someone who has HIV.

In the case of the 11 related diagnoses in Indiana, almost all were linked to injection drug use. Investigators discovered that syringe-sharing was a common practice in this community–often used to inject the prescription Opana; opioid oxymorphone (a powerful oral semi-synthetic opioid medicine used for pain.)  HIV can be spread through injection drug use when injection drug equipment, such as syringes, cookers (bottle caps, spoons, or other containers), or cottons (pieces of cotton or cigarette filters used to filter out particles that could block the needle) are contaminated with HIV-infected blood. The most common cause of HIV transmission from injection drug use is syringe-sharing. Persons who inject drugs (PWID) are also at risk for HCV infection. Co-infection with HCV is common among HIV-infected PWID. Between 50-90% of all persons who inject drugs are infected with both HIV and HCV.

The Investigation

“Contact tracing” is the process of identifying all individuals who may have potentially been exposed to an ill person, in this case a person infected with HIV.  Contact tracing involves interviewing the newly diagnosed patients to identify their syringe-sharing and sex partners.  These “contacts” are then tested for HIV and HCV infection, and if found infected are likewise interviewed to identify their syringe-sharing and sex partners. This cycle continues until no more new contacts are located.

As of May 18, contract tracing and increased HIV testing efforts throughout the community identified 155 adult and adolescent HIV infections. The investigation has revealed  that injection drug use in this community is a multi-generational activity, with as many as three generations of a family and multiple community members injecting together and that due to the short half-life of the drug, persons who inject drugs may have injected multiple times per day (up to 10 in one case). may be needed .

Early HIV treatment not only helps people live longer but it also dramatically reduces the chance of transmitting the virus to others.  People who do not have HIV and who are at high risk for HIV can also benefit more directly from the drugs used to treat HIV to prevent them from acquiring HIV.  This is known as pre-exposure prophylaxis (PrEP). Post-exposure prophylaxis, or PEP, is an option for those who do not have HIV but could have been potentially exposed in a single event.

The Response

So what is the next step in addressing this staggering outbreak? First, public health officials must work to get every person exposed to HIV tested. All persons diagnosed with HIV need to be linked to healthcare and treated with antiretroviral medication. Persons not infected with HIV are counseled on effective prevention and risk reduction methods; including condom use, PrEP, PEP, harm reduction, and substance abuse treatment. Getting messages about the benefits of HIV treatment to newly diagnosed individuals and prevention information to at-risk members of the community are key components to control this outbreak.

The underlying factors of the Indiana outbreak are not completely unique. Across the United States, many communities are dealing with increases in injection drug use and HCV infections; these communities are vulnerable to experiencing similar HIV outbreaks. CDC asked state health departments to monitor data from a variety of sources to identify jurisdictions that, like this county in Indiana, may be at risk of an IDU-related HIV outbreak.  These data include drug arrest records, overdose deaths, opioid sales and prescriptions, availability of insurance, emergency medical services, and social and demographic data. Although CDC has not seen evidence of another similar HIV outbreak, the agency issued a health alert to state, local, and territorial health departments urging them to examine their HIV and HCV surveillance data and to ensure prevention and care services are available for people living with HIV and/or HCV.

The work that has been done thus far, as well as the continued efforts being made to address this response, highlight importance of partnerships between federal, state and local health agencies. The work done by Indiana State Department of Health’s disease intervention specialist to link the initial HIV cases to this rural community, and the work of the local health officials to respond quickly and thoroughly to investigate all possible exposures and spread important health prevention information demonstrates the critical importance of strong public health surveillance and response.

The Division of HIV/AIDS Prevention commends the efforts of all the individuals involved in controlling the HIV outbreak in Indiana. The response illustrates that together we are committed to improving the health of our communities across the nation.