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Tuberculosis: diagnosis,treatment and control
2007-11-20 09:24:43
By Luumba Rashid
Last week we discussed three types of tubercobacil, its causes and some clinical findings. Today we will talk about diagnosis, its treatments and control.
The disease was discovered by Robert Koch in 1882, who later discovered glycerin-broth extract-tuberculin used for diagnostic purpose.
Diagnosis of disease.
The single most important diagnostic test for TB is the intradermal tuberculin test; diagnosis on clinical sign alone is very difficult.
Radiography (x-ray) is useful to small animals and non human primates while examination of sputum and other discharge is conducted microscopically.
Postmortem findings of the classic tuberculous granulomas could indicate the symptoms of the disease.
Confirmations of diagnosis require isolation and identification of the organism. However it could take a period of four to eight weeks for the tuberculin skin test that is widely used in large animals.
Control
The main reservoirs of infection are man and cattle. However other animals, domestic and feral pig have been found to be infected with Mycobacterium bovis.
The prevalence of the disease in such reservoirs influences the incidence of disease in other species.
The three principal approaches to the control of TB are
(1) test and slaughter approach, (2) test and segregation and (3) chemotherapy approach
The test and slaughter approach is the most effective method that can eradicate TB and it relies on the slaughter of reactors to the tuberculin test.
It is recommended that animals should be taken for tuberculin test every three months.
However, routine hygienic measures should aim at cleaning and disinfecting contaminated food and water troughs.
Treatment.
Treatment of TB cases have been attempted using drugs that have had some success in man and there are overriding arguments against therapy, based on the removal of infected animals.
However this risks the danger of encouraging drug resistance.
The application of pasteurized milk could be a major step in the fight against TB and continues to be an important control procedure in cattle.
Sheep and goats are said to be resistant to the disease but those infected develop lesions similar to those in cattle even though the organism may sometimes disseminate to other organs.
Pigs are susceptible to all three types of bacilli, but mycobacterium avium are most frequently isolated.
The mycobacterium bovis acquired from shared grazing or ingestion of dairy product, this can cause a rapidly progressive, disseminated disease with caseation and liquefaction of lesion.
Dogs may be infected with all three types of mycobacterium, but commonly from a human or bovine source. As we know dogs are very good friend of man.
Tuberculosis lesions are usually found in the lungs, liver, and other organs, while cats are resistance to mycobacterium tuberculosis but are susceptible to mycobacterium bovis and occasionally Mycobacterium avium.
The infected cats should be euthanized because of public health concerns.
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