BOVINE TUBERCULOSIS: EPIDEMIOLOGY & CONTROL IN INDIA

DANISH ALI , M.V.Sc. ScholarBHOJ R SINGH, Head

Division of EpidemiologyIVRI, Izatnagar

Bovine Tuberculosis

• A contagious zoonotic disease.• Caused by Mycobacterium bovis, rarely M.

tuberculosis may also infect.

History of Tuberculosis

• One of the most ancient diseases of mankind and animals

• 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 it wrong by discovering a round shaped bacterium that was the cause of the disease.

Mycobacterium bovis was subsequently identified in 1898.

Griffith isolated M. bovis from the sputum of a butcher suffering from pulmonary tuberculosis in 1909 .

In 1911 , it was clearly shown that M . bovis was able to cause all forms of tuberculosis in man and good number of children got infection through milk .

Until the 1920 , it was one of the major disease of the domestic animals throughout the world .

By 1937 , it was proved beyond doubt that pulmonary infection due to M bovis in man occurs inside the sheds by inhalation . [ Raw et al , 1937 ]

Classification of Mycobacteria1. Tubercle bacilli

a) Human – M. tuberculosisb) Bovine – M. bovisc) Murine – M. microtid) Avian – M. avium

Mycobacterium avium complex (M. avium and M. intracellulare).

e) Cold blooded – M. marinum2. Lepra bacilli

a) Human – M. lepraeb) Rat – M. lepraemurium

3. Mycobacteria causing skin ulcers

a) M. ulceransb) M. belnei

4. Atypical Mycobacteria (Runyon Groups)

a) Photochromogensb) Scotochromogensc) Nonphotochromogensd) Rapid growers

5. Johne’s bacillusM. avium ssp. paratuberculosis (MAP) IS900 and 251F positive.

Saprophytic mycobacteriaa) M. butyricumb) M. phleic) M. stercoralisd) M. smegmatise) Others

Mycobacterium tuberculosis complex A genetically related group of Mycobacterium

species that can cause tuberculosis in humans or animals.M. tuberculosisM. africanumM. bovis and BCG (Bacillus Calmette Guerin strain) strainM. microtiM. carnettiiM. capraeM. pinnipediiM. suricattaeM. MunqiAnd ill described the dassie and oryx bacilli.

•M. bovis is known to produce progressive disease in cattle and buffaloes. •The human and avian types of tubercle bacilli are responsible only for retrogressive lesions in the bovine species and are important for the nuisance they create in the pursuit of control program by bringing about tuberculin conversion of healthy individuals. •Before the introduction of the pasteurization process of milk, bovine TB was a serious problem all over India.

Disease in Bovines

PRE-DISPOSING FACTORS

Disease of Civilization / domestication:- herding together facilitates spread. Large herds and fattening herds of cattle are at increased risk.

Housing: Dark, ill ventilated, damp dwellings are favourable for the spread.

Heredity: Zebu cattle are somewhat more resistant than exotic or crossbred.

ROUTES OF INFECTION

• Respiratory route:- is the most common (About 90%).

• Alimentary route• Congenital :- infection is rare• Genital transmission is known to occur• Entry of infection through teat canal• Infection through the skin is also possible, though not

common.

• Probability of TB transmission depends on:– Infectiousness of animals with TB disease/ Stage

of disease.– Environment in which exposure occurred– Length of exposure– Virulence of the tubercle bacilli

• Transmission can be halted:– Isolate and segregate animals sick animals.– Provide effective treatment to infectious animal as

soon as possible or cull it.– Quarantine any new animal to be introduced.

TB Transmission

Prevalence of Tuberculosis in Animals

• ON THE BASIS OF TUBERCULIN TESTING:

Overall, 7.4% of livestock Bovines: 8%,Camels 11%,Sheep and goats 2%Pigs 15%, Wildlife 5% (ILRI,2012)

Animal tuberculosis in Indian states

PLACE YEAR PERCENTAGE NUMBERS TESTED

SPECIES

BANGALORE 1973 20 % DAIRY HERD BOVINES

HARYANA 1970 - 1979 1.9 % 11990 CATTLE

HARYANA 1970 - 1979 3.8 % 1099 BUFFALOES

MEGHALAYA 1982 8.94 % 302 CATTLE

UTTAR PRADESH

1985 13.25 % 1268 BOVINECARCASSES

PUNJAB 1994 0.33 – 11.7 % 1390 BOVINES

ORISSA 1997 1.6 – 11.5 % - POSITIVE REACTORS

- - 3.5 – 22.8 % ABBATOIRSURVEY

-

PLACE YEAR PERCENTAGE CONCERNED POPULATION

SPECIES REFERENCES

BOMBAY 1914 7.6 % DAIRY FARM674

CATTLE Joshi et al 1914

CALCUTTA 1970 4.64 % TUBERCULOUS COWS [ 64 ]

CATTLE Guha & Sarkar .

- 1969 1.6 - 16 % - CATTLE Lall 1969

- 1969 3 - 25 % - BUFFALOES Lall 1969

NORTHERNINDIA

2006 15.76 % DAIRY HERDS

BOVINE Mukherjee

WESTERN INDIA

2006 0.65 - 1.85 % DAIRY HERDS

BOVINE Mukherjee

HIMACHALPRADESH

2010 14.31 % OVERALL PREVALENCE

BOVINE THAKUR et al

HIMACHALPRADESH

2010 16. 67 % FARM PREVALENCE

BOVINE THAKUR et al

PLACES INCIDENCE OF CASES REFERENCES

PUNJAB 0.2 % - 16.3 % Datta , Iyer et al

BIHAR 1.06 % Soparkar & Dhillon et al

MADRAS 1.8 % Lall et al

BOMBAY 12 % Diwedi & Singh et al

TAMIL NADU 34.58 % Dhinakaran et al 1991

KARNATAKA 30 - 35 % Dhinakaran et al 1991

OGANISED DAIRY FARMS 1.93 % [cattle ] 6.39 % [buffaloes]

Shah 2002 .

Animal species affected

• Maintenance hosts– Cattle– Possums, ferrets– Badgers– Bison, elk – Kudu, African buffalo– White-tailed deer

• Spillover hosts– Sheep, goats, horses, pigs, dogs, others

• Spillback hosts

Cattle: Most among all • Bovine strain - most pathogenic over the other three strains.

• Incidence - more in pure bred and cross bred cattle.

• Zebu cattle - Comparatively resistant to bovine tuberculosis. (Selman, 1981).

• Tuberculosis in buffaloes is not uncommon in India (Lall et al., 1969); Mehrotra and Pathak, 1974; Kulshrestha et al., 1980).

Disease in Cattle

• Clinical signs– Develop over months– May become dormant, reactivate

• Early stage may be asymptomatic• Later stage ;

– Progressive emaciation– Fever, weakness, inappetence– Moist cough– Enlarged, draining lymph nodes

ADVANCED STAGE ;

• Fluctuating temperature• Anorexia and loss of body condition• Enlarged lymph nodes• Persistent cough progressing to dyspnoea • Increases respiratory rate if pulmonary tuberculosis• Induration of the udder

DIAGNOSIS ;

• Microscopic examination– Acid Fast Staining .

Delayed type hypersensitivity (DTH) assays includes ;

• Single intradermal tuberculin test • Stormont test • Short thermal test • Subcutaneous tuberculin test and • Opthalmic test

New techniques

• PCR assays such as multiplex PCR • Gamma-interferon (IFN-γ) assay • A combination of intradermal skin test (ST) and ELISA • Lymphocyte proliferation assay .• Serum based PCR.

Differential Diagnosis

• Bovine pleuropneumonia• Pasteurella• Corynebacterium pyogenes• Aspiration pneumonia• Traumatic pericarditis• Caseous lymphadenitis• Melioidosis• Chronic aberrant liver flukes

Post Mortem Lesions

• Granulomas (tubercles): Found in lymph nodes , and other organs– Appearance

• Yellow• Caseous• Calcified• May resemble abscesses

Resistance to disinfectants

• Bacilli survive in Droplets for 8 – 10 days .• Survive in 5% phenol, 15% Sulphuric acid 3% Nitric acid,5% oxalic acid, 4% Sodium hydroxide.

Contd …………….

• Mycobacterium are killed at 600c in 15 – 20 minutes

• In sputum they survive for 10 – 30 minutes

• Relatively resistant to several chemicals including Phenol 5 %

• Sensitive to Glutaraldehyde and Formaldehyde

• Ethanol is suitable application to superficial surfaces and skin gloves

• Caused by M. tuberculosis organisms resistant to at least one TB treatment drug

– Isoniazid (INH)– Rifampin (RIF)– Pyrazinamide (PZA)– Ethambutol (EMB)

• Resistant means drugs can no longer kill the bacteria

Drug-Resistant TB

Primary Resistance Caused by person-to-person transmission of drug-resistant organisms

Secondary Resistance Develops during TB treatment:

• Patient was not given appropriate treatment regimen OR• Patient did not follow treatment regimen as prescribed

Drug-Resistant TB

Mono-resistant Resistant to any one TB treatment drug

Poly-resistant Resistant to at least any 2 TB drugs (but not both isoniazid and rifampin)

Multidrug resistant (MDR TB)

Resistant to at least isoniazid and rifampin, the 2 best first-line TB treatment drugs

Extensively drug resistant (XDR TB)

Resistant to isoniazid and rifampin, PLUS resistant to any fluoroquinolone AND at least 1 of the 3 injectable second-line drugs (e.g., amikacin, kanamycin, or capreomycin)

Drug-Resistant TB

BOVINE TUBERCULOSIS PROPHYLAXIS / CONTROL

Why control???• Risk of infection to human• Loss in productivity• Animal market restrictions set by countries with advanced eradication

programs• Threat to endangered wild animal species

Failure of control programs in developing countries???• Cannot shoulder the cost of eradication program and compensate for

culled animals.• Limited access to education• Poor information networks• Lack of disease surveillance

Prevention & Control

1. Good hygiene and management

• Sanitation at farms and Good Ventilation • Tail-to-tail arrangement of keeping animals • Proper & hygienic disposal of waste • Isolation of sick and weak animals showing marked ; Weight loss, emaciation, low grade fever, coughing and diarrhoea

2. Tuberculin Testing • Segregation of all tuberculin positive animals • Test and slaughter policy in tuberculin positive animals other

than cows

CONTD……….Test-and-slaughter ;• If the incidence is low and the resources ample. Test-and-segregation ;• In the case of higher incidence of infection, coupled with

borderline level of economic security .Slaughter / Abbatoir surveillance Chemotherapy and vaccination ;• Consequently treatment and vaccination of infected animals is

not recommended .

Prevention and ControlWildlife reservoir hosts

– Complicate eradication efforts– Culling– Prohibit supplemental feeding– Barriers to feed access– Prevent contact with livestock

Center for Food Security and Public Health, Iowa State University, 2012

Problems of Tuberculosis control in India

No visible lesions or signs in reactors. Breakdowns / Anergic carriers. No Trace-back mechanism. Large un-organized contiguous mixing herds. Wildlife reservoirs and grazing animals in wild.

PovertyIlliteracySocial: Cow slaughter ban, rearing animals

till their natural death, common housing for human and animals.

Human Tuberculosis

CONCLUSION……….

• Mandatory Test-and-slaughter strategy or test-and-segregation.

• Periodic retesting of infected herd

• Quarantine• Trace back reactor and those

that came in contact with them• Strong Disinfection with iodine

solutions, glutarldehyde and formadehyde..

• Rodent control

• Barrier the area to prevent wildlife interaction with domestic animals.

• Pasteurization of milk• Awareness about the deleterious

effects of unpasteurized milk consumption.

• Proper cooking of meat.• Restricted animal movement.• Involvement of ministry of health

in coalition with agriculture industry for combined efforts to reduce bovine TB.

EFFORTS TO BE IMPLEMENTED…………………..