Published Date: 2005-03-13 23:50:00
Subject: PRO/AH/EDR> Strangles, equine - USA (CA)
Archive Number: 20050313.0739

STRANGLES, EQUINE - USA (CALIFORNIA)
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A ProMED-mail post
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International Society for Infectious Diseases
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Date: 12 Mar 2005
From: ProMED-mail <promed@promedmail.org>
Source: Peoples Daily online [edited]
<http://english.people.com.cn/200503/12/eng20050312_176510.html>

US health officials urge horse vaccination
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Los Angeles county health officials on Friday [11 Mar 2005] urged horse
owners in the western US county to vaccinate their animals, following an
outbreak of equine strangles, which can also affect people. Officials
ordered that horses thought to have been exposed to the disease be
quarantined by the health department.
About 15 horses at a stable in the northern part of the county have been
diagnosed with the disease, said Patrick Ryan, chief veterinarian with the
Los Angeles County Department of Health Services. He said about 4 percent
of infected horses die from the disease.
Some people at the affected stables have exhibited flu-like symptoms, and
health officials are "looking into" whether they caught the disease from
the horses.
Equine strangles is "not terribly common" in humans, but it does occur,
said Dr. Jonathan Fielding, the county's public health director. People who
have handled an infected horse can carry the organism, and the disease may
affect humans with suppressed immune systems.
Strangles, a highly contagious upper respiratory bacterial infection, is
among the oldest and more dangerous horse diseases, according to health
officials. It's a respiratory disease somewhat like the flu, except it's
caused by bacteria rather than a virus, Ryan said. The disease can affect
horses, donkeys and mules of all ages, but, most frequently, those younger
than 2 years old.
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ProMED-mail
<promed@promedmail.org>
["Strangles," due to _Streptococcus equi_ seems to be sporadic throughout
the US. It is highly contagious, with a high morbidity and low mortality,
but is seen essentially only in horses, donkeys and mules. These California
human "cases" may well be just coincident "colds" and such that are going
around in a sympathetic species. But transmission of S. equi to humans from
domestic animals has been reported and these streptococci cause infections
very similar to those caused by group A streptococci (S. pyogenes) in
humans ranging from pharyngitis to more invasive ones such as skin and soft
tissue infections, pneumonia and sepsis. Transmission of _S. equi_ occurs
through fomites and direct contact. Carrier animals are important for
maintenance of the bacteria between outbreaks. Under ideal circumstances,
the organism can survive outside the host for some 7-9 weeks. Thus paddocks
and stables used by infected horses should be regarded as contaminated for
some 2 months after outbreak resolution.
Clinically affected horses should be physically separated from all other
horses and cared for by a separate team of caregivers. Most horses will
continue to shed _S. equi_ for about a month following recovery. Therefore,
3 negative nasopharyngeal swabs at 4-7 day intervals should have been
obtained before release from quarantine. Prolonged shedding for up to 18
months has been recorded.
The clinical attack rate can be reduced by 50 percent through the use of an
intranasal live vaccine. For appropriate treatment of clinical cases, use
your veterinarian. While antibiotic therapy works, it is optimum to have
the horse develop a protective immune response so that the infection does
not reappear after cessation of treatment. - Mods.MHJ/LM]

See Also

2004
----
Strangles, equine - USA (GA) 20040419.1088
1997
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Strangles, horses - USA (Louisiana) 19971203.2416
Strangles / equine influenza, horses - Philippines 19971123.2354
...................mpp/mhj/msp/lm/mpp

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