Tuberculosis-A Zoonotic Disease
A bovine tuberculosis-A zoonotic disease is a mammal disease especially in cattle caused by the bacteria mycobacterium bovis (M. bovis). While in human tuberculosis caused by mycobacterium tuberculosis which is different from M. TB. The term tuberculosis originate from nodules called tubercles which form in the lymph nodes o disease animals.
Spread/ transmission:
It is a contagious and a zoonotic disease. The major spread is due to contact with diseased animals through inhalation or ingestion of the bacteria.
The infected animals can spread disease to healthy animals through:
- Respiratory route
- During pregnancy
- Through oral route
- Environmental contamination
While in human it transfers by using raw milk and meat or by direct contact with infected animals.
Distribution:
Cattle is the main host of m. bovis but it has been reported in many other domesticated and non-domesticated animals such as sheep goat deer foxes and camel E.T.C.
This disease is found globally specially in U.S, Africa and part of Asia. The develop country do strategies to eliminate or reduce it.
In 2014, 9.6 million people were infected and 1.5 million people died due to this disease according to WHO. 10 % human cases of tuberculosis are due to bovine TB.
Clinical sign:
Bovine tuberculosis may be sub-acute or chronic. The causal organism of bovine TB takes several times to infect the host, while in few cases it severely affected the animals within a few months.
The clinical symptoms include:
- Lymph nodes prominent
- Weakness
- Loss of appetite
- Diarrhea
- Cough
Diagnosis :
- The method to detect tuberculosis is the TB skin test, which measure skin thickness after applying injection intradermally. In this culture of bacteria is grow in laboratory which take almost 6-8 moths.
- In the detection of infection in a herd, MS may allow the employ of the in vitro interferon gamma (IFN-Y). Both in vivo and in vitro assay we use purified protein derivatives
(PPDS) which we obtained from heat treated products of growth and lysis of bovine TB
- Intradermal tuberculin test has been used more than 100 years to detect the disease. In 1890 Fireland was the 1st country start a campaign to eradicate bovine TB by tuberculin
test.
Control:
Initially skin test and slaughter of infected animal have been implemented to control disease.
- Restrict the movement of infected animal and keep watching on the movement of
animals.
- Inspect meat of animal, to prevent it to enter in food chain.
- Pasteurization of milk before use it.
- Vaccination of animals
.
Public Health Risk:
It is zoonotic and contagious disease.
Zoonotic diseases: the diseases which spread from animals to human.
Contagious diseases: the disease which transmit from one person to another person.
In human it transmits by milk or meat of animal infected by M. bovis or direct contact with infected animal. clinically, it is not possible to differentiate infection caused either by M. tuberculosis. It is estimated that 10% human cases of TB are due to bovine TB.
- Effect of tuberculosis on human
Transmission of tuberculosis in humans:
- TB is a zoonotic disease it transmits from infected animal by using raw meat and milk
enter in food chain.
- It transmits mostly in those people who have direct contact with animals such as dairy workers.
- Inhalation of bacteria present in environment exhaled by animals infected with bovine TB.
- It also transmits from person to person by physical contact or when infected person sneeze.
Symptoms:
Symptoms of bovine TB is same as TB in human:
- Fever
- Night sweat
- Diarrhea
- Weight loss
- Abdominal pain
- Cough
Diagnose:
Mostly people are at low risk, it occurs mostly who have direct contact with animal such as worker of slaughter house or butchers or people use raw milk and meat. So, they consult their public healthcare.
Screening test includes:
- Skin test
- Interferon-gamma release assay (blood test)
Treatment :
Its treatment is similar to M. tuberculosis. The only antibiotic pyrazinamide is available.
