Extensive epidemiological investigation followed by
prevention and treatment interventions have largely succeeded in controlling an
outbreak of HIV and hepatitis C virus (HCV) infection in rural Indiana, USA,
linked to injection of prescription opioids, but new cases continue to appear
and many other communities may be at risk for similar outbreaks, according to
presentations at the Conference on Retroviruses and
Opportunistic Infections (CROI 2016) last week in Boston.
John Brooks of the HIV
epidemiology team at the US Centers for Disease Control and Prevention (CDC) gave an update on
the evolving Indiana HIV outbreak among people who inject drugs at a plenary
session on the final day of the conference, while Sumathi Ramachandran discussed how genetic analysis shed light on HCV
transmission networks involved in the outbreak.
As background, Dr Brooks noted that, at the end
of 2014, “things looked pretty good for people who inject drugs” in terms of
HIV, as incidence had declined dramatically in this population and people who
inject drugs accounted for only 6% of new infections in 2014 – down from around
30% in the early 1990s.
But in January 2015, the Indiana State
Department of Health began investigating an HIV outbreak after epidemiologists
confirmed nearly a dozen new infections, primarily among people who inject
drugs, centred around the town of Austin (population 4200) in rural Scott
County, which had less than one case per year during the previous decade. Indiana
and CDC investigators published an initial
report on the outbreak in the May
1 edition of CDC’s Morbidity and
Mortality Weekly Report.
Dr Brooks previously presented an overview of the Indiana
cluster at the International AIDS Society
conference last July, describing efforts to determine
the source of the outbreak, trace patterns of transmission, halt further
infections and bring affected people into care.
Newly diagnosed individuals were asked to suggest any injection or sexual
partners or other social contacts they thought might benefit from an HIV test. Of
the nearly 500 individuals so identified, by mid-June 170 people were found to have
HIV, 90% of whom also had HCV.
The outbreak then slowed, but a small number of cases continue to be identified.
A “retesting blitz” in
November picked up some new
cases, and the Indiana health department announced last
month that four recently confirmed cases had brought the total to
188. The recent cases were mostly among people who
had not been tested during the earlier round or were tested upon incarceration,
Dr Brooks said, but one person who had previously tested HIV-negative had
become positive. HIV prevalence is now 4.6% in
Austin and about 1% in Scott County –
comparable to hard-hit cities like New York City and San Francisco.
This outbreak differed in several ways from others
previously seen among people who inject drugs in the US. The newly diagnosed
population is rural, almost all white, and includes a substantial proportion of
women (42%); the median age was 34 years. Dr Brooks noted that in some cases
drug use was multi-generational, with “parents, children and grandchildren
injecting together”. In contrast, prior outbreaks have traditionally
involved inner-city residents, a majority African-American or Latino, with nearly
twice as many men as women.
The most commonly injected drug was oxymorphone
(Opana), a prescription opiate-like
painkiller. Some also injected heroin, methamphetamine, cocaine, oxycodone and
methadone. The reported number of daily injections ranged from 4 to 15, which
Dr Brooks said is high, explaining that oxymorphone is expensive (up to $200 a tablet) and the population is poor, so “people
injected as little as possible to stop being sick, but it wore off quickly and
they had to inject a lot.”
The Indiana outbreak goes along with a trend of rising
deaths in the US that now exceeds traffic fatalities, primarily due to prescription opioids
and heroin and often affecting rural and suburban communities lacking harm reduction services (described in the January 1 Morbidity
and Mortality Weekly Report). Like Scott County, affected
communities typically have high rates of poverty, unemployment, low education levels
and limited access to insurance and health services.
The combined local, state and federal/national
response to the Indiana outbreak included linkage to HIV care and antiretroviral
therapy (ART), offering pre-exposure prophylaxis (PrEP) for people at ongoing
risk, helping people access hepatitis C therapy and offering
medication-assisted treatment for drug addiction.
“We tried to get many people on ART to reduce
community viral load – that’s the most potent prevention intervention we have,”
Dr Brooks stressed. In addition, PrEP is being provided to
people who inject drugs and their sexual partners, and he said there is greater
interest and more people asking about it. In the announcement about the four most
recent cases, the Indiana health department urged people at risk to ask their healthcare
providers about PrEP.
Given that much of the affected population is poor and
lacks basics such as the identification needed to get health insurance,
officials set up a ‘one-stop shop’ where people could apply for driver licences,
sign up for health insurance and get other social services. Luckily, Dr Brooks noted,
Indiana had just expanded its Medicaid program for low-income people in early
2015. (The Affordable Care Act of 2010 enabled states to expand their Medicaid
programs using federal funds to include people up to a higher income threshold;
17 states still have not done so.)
As part of the response, Indiana declared a public health emergency that allowed local governments
to establish otherwise-illegal syringe exchange programmes. As reported at the IDWeek
2015 conference last October, implementation of an emergency
syringe programme serving Scott County led to a decrease in risk behaviours
including needle sharing in its initial months.