ZOONOTIC TUBERCULOSIS in ELEPHANTS

Dr Sakshi Dubey, MVSc. Scholar, EpidemiologyDr. Bhoj R Singh, Principal Scientist & Head, Division of EpidemiologyIVRI, Izanagar, Bareilly, UP, India

Tuberculosis

One of the most ancient diseases of mankind and animals A contagious zoonotic disease Aristotle was first to say that tuberculosis is an airborne

disease. In 1865 Jean Antoine Villemin, put out the idea that TB

was genetically inherited. In1882 Robert Koch proved Villemin wrong by discovering

the bacterium causing the disease. It is caused by Mycobacterium spp.

Indian scenario

Endemic in most parts.Holds about 21% of the total global TB

cases1000 Indians die from TB per day. (Krishnaswami,

2000) One third of the population is suffering

from TB.

Global Scenario

2nd most common infectious cause of deaths (WHO 2013)

Human TB (zoonotic 3-10%) - localized in High Burden Countries (India, China, Indonesia, Nigeria, Bangladesh, and Pakistan)

22 High Burden Countries including India house for 80 % of all new TB cases.

In developing countries ~10.5% of human cases are associated with M. Bovis (ILRI,2012).

GLOBAL TB PROGRAMME

Estimated number of cases

Estimated number of deaths

1.4 million*(1.3–1.6 million)

8.7 million(8.3–9.0 million)

Up to 0.5 million

All forms of TB

Multidrug-resistant TB

HIV-associated TB 1.1 million (13%) (1.0–1.2 million)

430,000(400,000–460,000)

Source: WHO Global Tuberculosis Report 2012 * Including deaths attributed to HIV/TB

The Global Burden of TB -2011

Unknown, but probably > 150,000

Incidence rates, 2011 ( WHO )

Highest rates in Africa, linked to high rates of HIV infection~80% of HIV+ TB cases in Africa

Per 100 000 population≥300

150–29950–149

0–2425–49

Prevalence in Animal

Overall, 7.4% of livestock Bovines: 8%,camels 11%,Sheep and goats 2%Pigs 15%, Wildlife 5%

(ILRI,2012)

 

Tuberculosis in wild animals

A number of cases reported among wild animals worldwide.

In zoo primates TB is due to M. tuberculosis and M. bovis

In Larger land mammals (Ungulates), TB is mostly caused by M. bovis.

M. tuberculosis is the main cause of TB in Elephants, Rhinoceroses, Tapirs, and in some exotic bovine spp.

Tuberculosis in wild animals

TB in a chimpanzee at London zoo reported by Owen (1961)

TB in Tigers of Delhi and Darjeeling Zoos (Rathore and Khera, 1981)

TB in Lions of zoological garden Bombay (Das and Jayaro, 1986)

M. tuberculosis reported in some exotic carnivores and Psittacine birds.

Tuberculosis in wild animals

Wildlife Reservoirs

of TB

Eurasian badger (Meles meles) UKWhite-tailed deer (Odocoileus virginianus) USA

Wild boar (Sus scrofa) Spain

Cape buffalo (Syncerus caffer) Africa

Brush-tailed possum (Trichosurus vulpecula) New Zealand

(Wilson et al., 2009)

Tuberculosis in Elephants

Described in Asian documents of over 2000 years old

1st report of TB in elephants made in London zoo in 1875

Sporadic TB in Asian elephants and 1st case in African elephant reported in mid 20th century (Gorovitz, 1962)

During 1997 transmission of TB between human and elephants reported (Michalak et al., 1998)

Epidemiology

Though it is also found in free ranging animals, tuberculosis found more commonly in captive animal worldwide.

In Asian elephants mostly M. tuberculosis and M. bovis are involved.

(Abraham et al., 2010 and Mikota et al., 2007)Female seems to be affected more than the male

elephants (Karthik, 2012)

Prevalence of TB in Asian elephants is about 15% in India and 13% in Nepal

(Abraham et al., 2010 and Mikota et al., 2007)

In United States of America (USA), its prevalence in elephants is 6.3%

(Mikota et al., 2000)

The transportation is possible between the elephants by the way of trumpeting and trunk spray.

Transmission to elephants Humans activity can lead to an increased

level of M. tuberculosis being shed into the environment and may result in the spillover of infection into wildlife populations

(Mikota, 2008)

Development of TBInhalation of bacteria

Bacteria reach lungs, enter macrophages

Bacteria reproduce in macrophages

Lesion begins to form (caseous necrosis)

Bacteria cease to grow;lesion calcifies

Activated macrophages

reactivation

Immune suppression

Lesion liquifies Bact coughed up in sputum

Spread to blood,organs

death

Clinical signs

No typical signs in elephantNon specific signs includes:

InappetanceWeight lossSubcutaneous ventral oedema(Kay et. al. 2010)

Zoonotic aspects

By aerosolization my spread to:Elephant handlersZoo employees, veterinarians Other animals

Pathology

Involves primarily :Lungs Thoracic & Bronchial lymph nodesExtra thoracic sitesCaseous and mucopurulent exudates in trunk

Histological findings:

Epethelioid granulomas with giant cellPyelogranulomatous pneumonia

Diagnosis

Intra-dermal Tuberculin Test Microscopic examination

Acid Fast Staining Serological test

Elephant TB STAT-PAK® AssayMulti-antigen print immunoassay (MAPIA)ELISA

Molecular testPCR

Isolation and identification of Mycobacterium speciesSample: Trunk wash, Blood/Serum“Triple sample method”Lowenstein Jensen medium

TREATMENT

S. No. Drug Does (mg/kg)

Route Target conc. (µg/ml)

1. Ethambutol 30 Oral 2-5

2. Isoniazid 5 Oral/rectal 3-5

3. Pyrazinamide 30 Oral/rectal 20-60

4. Rifampin 10 Oral 8-24

(Guideline for control of tuberculosis, 2008 and Peloquin et al., 2006)

Dose and route of administration of Anti-Tubercular drugs in Elephants

• Standard protocol includes:

• 2 months with Isoniazid, Rifampin, Pyranzinamide & Ethambutol

• followed by 4 months of isoniazid and rifampicin (Daly et al.,

2006)

Tuberculosis Management Options

Conclusion

TB is endemic in captive elephants

The role played by elephants in the spread of TB to humans needs to be addressed.

Regular screening of elephants for TB is required for control.

Research on tuberculosis in elephants is required