Re: Elephant blamed for workers' TB at a Tennessee sanctuary in 2009
<TABLE id=apex_layout_271110100662109808 class=formlayout border=0 summary=""><TBODY><TR><TD noWrap align=right>
Archive Number</TD><TD noWrap align=left>20110219.0546</TD></TR><TR><TD noWrap align=right>
Published Date</TD><TD noWrap align=left>19-FEB-2011</TD></TR><TR><TD noWrap align=right>
Subject</TD><TD noWrap align=left>PRO/AH/EDR> Tuberculosis, humans, elephant - USA: (TN) 2009</TD></TR></TBODY></TABLE>
TUBERCULOSIS, HUMANS, ELEPHANT - USA: (TENNESSEE) 2009
******************************************************
A ProMED-mail post
<
http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<
http://www.isid.org>
Date: Thu 17 Feb 2011
Source: Reuters [edited]
<
http://www.reuters.com/article/2011/02/18/us-elephant-tuberculosis-idUSTRE71H01J20110218>
Liz, an African elephant housed at a sanctuary for the animals, was
the source of tuberculosis infections among 8 workers at the refuge,
an author of a report on the 2009 outbreak said on Thursday [17 Feb
2011]. None of the infected employees at the Hohenwald, Tennessee,
sanctuary for old, often abused, elephants, became ill. The workers
were given preventive therapy, and 54-year-old Liz is in quarantine
and undergoing treatment.
A report by The Centers for Disease Control and Prevention [CDC]
blamed pressure-washing of elephant barns for the spread of the
tuberculosis bacteria [_Mycobacterium tuberculosis_], which enters
through the lungs, said Dr. William Shaffner, who helped write the
report and is an expert on infectious diseases at Vanderbilt
University in Nashville. "Elephants can excrete the bacteria through
their trunks and even in their feces," which can become an aerosol
mist when hit by pressurized water, said Shaffner, who is also
president of the sanctuary that is 85 miles South of Nashville.
The mist exposed the workers inside the barn and drifted into an
adjacent administrative building where 3 other employees inhaled it,
the report concluded. This should serve as a warning to handlers that
even those with indirect contact with elephants can be infected,
Shaffner said.
An estimated one in 8 captive elephants is infected with tuberculosis,
he said. There are as many as 600 captive elephants in the United
States. Workers at the sanctuary who deal directly with the elephants
now wear more elaborate protective clothing and use lower-pressure
hoses to clean the barns, and steps were taken to seal off vulnerable
buildings. The Tennessee sanctuary was created in 1995 and houses 14
African and Asian elephants where they can wander on 2700 acres.
While elephants can spread the bacteria among themselves and to
humans, Shaffner said the 1st elephant to get tuberculosis likely got
it from an infected person.
[Byline: Andrew Stern and Greg McCune]
--
Communicated by:
HealthMap Alerts via ProMED-mail
<
promed@promedmail.org>
[_Mycobacterium tuberculosis_ and _Mycobacterium bovis_ cause
tuberculosis with a similar clinical picture in both elephants and
humans (<
http://www.medscape.com/viewarticle/572559_3>;
<
http://www.ncbi.nlm.nih.gov/pubmed/8593405>; and
<
http://thorax.bmj.com/content/64/1/89.abstract>).
The news release above, however, fails to specify which species of
_Mycobacterium_ is causing Liz the African elephant's infection.
The news release does state that the 8 workers with tuberculosis
infection at the elephant refuge were not ill, which is consistent
with a diagnosis of latent tuberculosis infection (LTBI). LTBI is
detected by a positive tuberculin skin test (TST) or special blood
test known as an interferon gamma release assay (IGRA). IGRA detects
the amount of interferon gamma released by T cells in response to
exposure in vitro to 2 proteins that are secreted by all strains of
_M. tuberculosis_ and pathogenic strains of _M. bovis_, but that are
absent from Bacillus Calmette-Guerin or BCG (a vaccine strain derived
from attenuated (weakened) _M. bovis_) vaccine strains and most
non-tuberculous mycobacteria
(<
http://www.nejm.org/doi/pdf/10.1056/NEJMp068015>).
False positive TST can result from prior vaccination with BCG or from
infection due to non-tuberculous mycobacteria. However, IGRAs are
reportedly not affected by prior BCG vaccination. The news release
above fails to state if the workers were tested because of exposure to
an elephant found to be ill with active tuberculosis, or if the
workers were tested routinely as part of an on-going program to
periodically test workers for LTBI because of an occupational risk.
Tuberculosis is usually spread by means of aerosolized droplet nuclei,
about 1-5 microns in diameter, that contain one or 2 tubercle bacilli
(<
http://ajrccm.atsjournals.org/cgi/content/full/169/5/553>). Droplet
nuclei are expelled from a case of active pulmonary, especially
cavitary, tuberculosis during activities such as coughing or sneezing
in either a human or elephant; the airborne particles can remain
suspended in the air for several hours, depending on the environment,
carried by air currents.
Usually for a person to become infected, contact with an infectious
source needs to be close and prolonged, and to occur in an enclosed,
poorly ventilated space. This may explain how 5 of the employees with
LTBI who worked inside a barn with the sick elephant became infected.
Outdoors, airborne organisms would be expected to be diluted and
quickly killed by UV rays in sunlight
(<
http://www.ghdonline.org/ic/discussion/viability-of-tb-organisms-in-air/>).
After exposure to known isoniazid (INH)-susceptible TB or TB of
unknown drug susceptibility, for a person who has a positive TST or
IGRA result or who converts their tests from negative to positive
after retesting in 8-10 weeks and has no evidence of active
tuberculosis, the CDC-preferred LTBI treatment regimen is INH for 9
months (see <
http://www.cdc.gov/tb/publications/LTBI/treatment.htm>).
If the person was exposed to known INH-resistant TB, the preferred
regimen is rifampin for 4 months. If person was exposed to known
multidrug-resistant TB (MDR-TB), a consultation with an expert in the
treatment of MDR-TB is suggested.
The CDC recommends that: LTBI treatment should be initiated in
TST-negative children aged 9 months - 5 years and in immunocompromised
persons of all ages who have negative TST or IGRA results; Treatment
should be continued until the results of the 2nd test and other
medical evaluation are known; For some contacts at very high risk, a
full course of LTBI treatment may be recommended even in the absence
of a positive TST or IGRA result; Consultation is recommended with the
local TB control program about the management of such contacts (see
<
http://www.cdc.gov/tb/publications/LTBI/treatment.htm>).
The HealthMap/ProMED-mail interactive map of the USA, showing the
state of Tennessee, is available at: <
http://healthmap.org/r/0eqQ>. -
Mod.ML]
[see also:
Tuberculosis, elephants - France: (Rhone)
20110218.0536
Tuberculosis, elephant - Australia (02)
20110211.0467
Tuberculosis, elephant - Australia 20110208.043
2010
----
Tuberculosis, elephants - Nepal
20100520.1665
2009
----
Tuberculosis, elephants - Nepal
20090517.1844
2008
----
Tuberculosis, elephants - India: south
20080910.2830
2007
----
Tuberculosis, elephants - Nepal (05)
20070706.2145
Tuberculosis, elephants - Nepal (04)
20070702.2111
Tuberculosis, elephants - Nepal (03)
20070624.2039
Tuberculosis, elephants - Nepal (02)
20070620.1990
Tuberculosis, elephants - Nepal
20070616.1962
2001
----
Tuberculosis, elephants - USA (02)
20010119.0151
Tuberculosis, elephants - USA
20010103.0012
1998
----
Tuberculosis, elephants - USA (California) (06)
19980430.0842
1997
----
Tuberculosis, elephants - USA (California)
19970630.1408]
....................ml/ejp/jw
http://www.promedmail.org/pls/apex/..._BACK_PAGE,F2400_P1001_PUB_MAIL_ID:1000,87152
