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Considerable overlap between HIV and Shigella epidemics in the UK
Michael Carter, 2016-04-26 10:00:00
third of cases of non-travel-related Shigella dysentery in the UK involve
HIV-positive patients, according to research presented to the annual conference
of the British HIV Association in Manchester last week. Most of these cases were in men who have sex with men (MSM) living with HIV. The investigators believe their findings confirm previous
research showing that HIV-positive MSM are a new high-risk group for Shigella,
with the infection being transmitted sexually.
Shigella is a
bacterial infection that can cause severe dysentery. Historically, cases in the
UK have been associated with travel to low-income countries with poor hygiene.
It is highly infectious and has very unpleasant symptoms, including fever,
severe bloody diarrhoea and abdominal cramps. Complications can include dehydration,
and more rarely, bacteraemia, Reiter’s syndrome (a type of arthritis that occurs when
bacteria enters the body) and a syndrome that can lead to kidney failure.
Outbreaks of Shigella
have been documented in MSM since the 1970s. A new profile of Shigella patients
is emerging in the UK and similar countries. Cases often involve HIV-positive
MSM, reporting sexual activities such as rimming (anal-oral contact) and
fisting, high numbers of sexual partners, dense sexual networks, “chemsex” and
attendance at sex parties. This risk profile overlaps with that for other
emergent sexually transmitted infections in HIV-positive MSM, including
hepatitis C virus (HCV), lymphogranuloma
venereum (LGV) and resurgent
Diagnoses of travel-related Shigella in the UK have
been increasing steadily since 2004, reaching a peak of approximately 700
cases in 2010 before falling to a little over 400 diagnoses in 2014.
Non-travel-related diagnoses overtook travel-related
diagnoses in 2012 and over 800 non-travel-related cases of Shigella were
diagnoses in 2014.
A team of investigators from Public Health England
used nationally collected surveillance data to determine the role of HIV in the
UK’s ongoing Shigella epidemic.
Information on all 10,027 Shigella diagnoses made
between 2003 and 2015 was obtained. This included date of diagnosis, age and
association with travel. The investigators also obtained data on all 139,950
HIV cases diagnosed in the UK, including gender, sexuality, clinical data and
date of diagnosis. The two datasets were anonymously linked, enabling the
researchers to determine the proportion of Shigella cases that involved
patients with HIV, the proportion who were MSM and temporal trends in
Overall, 1184 (12%) Shigella diagnoses were in
patients with HIV. When diagnoses were broken down according to their
association with travel, it was revealed that 1050 of these cases were
non-travel-related and just 134 were related to travel.
Relatively few travel-related diagnoses involved
HIV-positive men (5%) or women (1%).
But when non-travel-related cases were examined, it was
shown that 30% of all diagnoses were in HIV-positive men and 2% involved
Closer analyses of non-travel-related cases in
HIV-positive men showed that 94% involved MSM. Just under a half were taking
HIV-therapy and 69% had a viral load below 400 copies/ml.
Diagnoses of non-travel-related Shigella among
HIV-positive men increased steadily from 55.5 per 100,000 diagnosed HIV
population in 2005 to 364.4 cases per 100,000 by 2014. An especially sharp
increase in diagnoses was recorded after 2011.
The investigators conclude that 30% of men diagnosed
with non-travel associated Shigella were diagnosed with HIV and most of these
were MSM. The investigators recommend that all HIV-positive men presenting with
lower gastrointestinal tract infections should be considered for Shigella. They
also believe their findings are consistent with current understanding about
high-risk sexual behaviour among HIV-positive MSM.