- The TB response effort in Nepal needs to include screening
and treatment of the elephant handlers as well as the elephants, because
both human-to-elephant and elephant-to-human transmission of tuberculosis
are known to occur (Michlak et al 1998; Davis 2001).
-
- It is possible that the index case in elephants was caused
by human-to-elephant transmission from an infected human keeper or 'mahout',
given the prevalence of human TB in Nepal. Statistics provided in a recent
paper by Newell and colleagues (2006; see reference 3 below), indicate
that
-
- - 60 percent of Nepal's adult human population is infected
with _Mycobacterium tuberculosis_; - more than 80 000 have active TB infections;
- 44 000 people develop active disease every year, of whom 20 000 have
active infectious TB; - 6000-8000 people die from TB annually - male-to-female
ratio of registered TB patients is 2:1.
-
- Given the high prevalence of TB in humans in Nepal, it
is evident that any long-term solution to this problem must be an integrated
veterinary/public health approach that includes testing and treatment of
both elephants and their human counterparts.
-
- References:
- 1. Michalak K, Austin C, Diesel S, Bacon JM, Zimmerman
P, Maslow JN.
- 1998: _Mycobacterium tuberculosis_ infection as a zoonotic
disease:
- transmission between humans and elephants. Emerging Infectious
- Diseases 4(2) (available at
- http://www.cdc.gov/ncidod/eid/vol4no2/michalak.htm>)
-
- 2. Davis M. 2001. _Mycobacterium tuberculosis_ risk for
elephant
- handlers and veterinarians. Applied Occupational Health
&
- Environment, 16:3, 350-3 (available at:
- http://www.informaworld.com/smpp/ftinterface~content=a713832024~fulltext
- =713240930>)
-
- 3. Newell JN, SC Baral, SB Pande, DS Bam, P Malla. 2006:
- Family-member DOTS and community DOTS for tuberculosis
control in
- Nepal: cluster-randomised controlled trial. LANCET 367(9514):
903-9
- (abstract available at
- http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve
- &db=pubmed&dopt=Abstract&list_uids=16546538)
-
- --
- From Joseph P. Dudley, Ph.D.
- Science Applications International Corporation
- 12530 Parklawn Drive Suite 350
- Rockville MD 20852
- dudleyjp@saic.com
-
- Tuberculosis has been recently reported in 10 domesticated
elephants in a national park in southern Nepal (see ProMED-mail posting
Tuberculosis, elephants - Nepal 20070616.1962). Tuberculosis in elephants
is clinically similar to the disease in humans. These elephants in Nepal
are apparently used in safaris by private hotels and state-run national
parks. Elephants are a protected species in Nepal and killing them carries
a jail term of up to 15 years. A program for the diagnosis and treatment
of tuberculosis in elephants is being initiated by the Nepalese and supported
by "Elephant Care International" (see ProMED-mail posting Tuberculosis,
elephants - Nepal (02) 20070620.1990).
-
- Tuberculosis is spread via infectious aerosols of respiratory
secretions that contain a high _M. tuberculosis_ load and are generated
by coughing or sneezing by patients with cavitary pulmonary tuberculosis
and presumptively by trumpeting infected elephants. These aerosols remain
suspended in air for prolonged periods of time in closed, poorly ventilated
settings, such as barns. It is in such a barn setting that zoonotic transmission
of tuberculosis between handlers and infected elephants, confirmed by DNA
fingerprinting, apparently occurred, as reported by Michalak et al 1998
(see reference 1 above). Presumably, the risk of transmission would be
small for persons with brief contacts with elephants in the outdoors, as
would occur with tourists. Elephants in the wild are said to be free of
tuberculosis.
-
- In Nepal the diagnosis of pulmonary tuberculosis in humans
is likely made only on the basis of a positive sputum smear for acid-fast
bacilli (see reference 3 above, Newell et al Lancet 2006), without the
benefit of speciation or antimicrobial susceptibility testing. The report
from Nepal does not state whether the isolates were _M. tuberculosis_ or
_M. bovis_. _M. bovis_ has been isolated from an elephant in the USA (Summary.
Elephant Tuberculosis Research Workshop. Orlando, FL 21-22 May 2005. This
is a detailed description of the history, diagnosis, and treatment of tuberculosis
in elephants, available at
-
- http://www.elephantcare.org/protodoc_files/2005/Elephant%20
- Tuberculosis%20Research%20Workshop%20May%2005.pdf
-
- Although the prevalence of _M. bovis_ infection in people
or other animals is unknown because of the complexity and cost of differentiating
_M. bovis_ from other members of the _M. tuberculosis_ complex, _M. bovis_
infection is nevertheless likely to be widespread in developing countries
such as Nepal. Treatment of tuberculosis in elephants is reported to be
similar to that in humans, and involves use of a combined regimen of INH
(isoniazid), RIF (rifampicin), PZA (pyrazinamide), and ethambutol. However,
_M. bovis_ is inherently resistant to PZA and susceptibility testing to
PZA is not routinely performed. A 6-month, short-course anti-mycobacterial
therapy in humans depends on having PZA as part of the drug regimen; without
this drug, therapy must be prolonged beyond 6 months. Also, MDR TB (multidrug-resistant
TB) is likely to be prevalent in Nepal and further complicate treatment
in elephants and their human contacts in this country. - Mod.ML
-
-
- Patricia A. Doyle DVM, PhD
- Bus Admin, Tropical Agricultural Economics
- Univ of West Indies
-
- Please visit my "Emerging Diseases" message
board at:
- http://www.emergingdisease.org/phpbb/index.php
- Also my new website:
- http://drpdoyle.tripod.com/
- Zhan le Devlesa tai sastimasa
- Go with God and in Good Health
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