Tbphases.doc 5 March 2007

STRATEGICAL PHASES OF BOVINE TUBERCULOSIS ELIMINATION AT NATIONAL LEVEL

V. Kouba

Former Czechoslovak and Czech Chief Epizootiologist, Prague and Professor of Epizootiology, University of Veterinary Sciences, Brno

(Provisional text to be finalized and edited)

1. Introduction

First report about the occurrence of tuberculosis in cattle caused by Mycobacterium bovis in the territory of future Czechoslovakia was published in 1897. First half of 20th century brought more information thanks to slaughterhouse findings and ad hoc allergic testing. In 1959 all cattle population was tested using PPD tuberculin. Situation was catastrophic: 21.03 % of cattle total, 32.26 % of cows and almost all large ranches were affected. Hundreds of human cases of M. bovis were reported annually, mainly among the children. Elimination strategy was based upon cattle population reproduction process. For the breeding the calves initially also from tuberculosis cows and later from healthy ones only were used. Testing of cattle population twice a year helped to discover all outbreaks. Elimination programmes were elaborated at all affected ranges, all regions, provinces and at national level. Among the measures belonged obligatory pasteurization of milk, veterinary services reinforcement (in terms of staff, facilities, equipment, funds, etc.), target-wise research, legislation, training, extension and provision of subsidizes. Zero prevalence was reached by the end of 1968. All 1,363,000 heads of tuberculosis cattle were replaced by healthy animals. Production of milk increased by 56.33 % and of beef by 47.11 %. Specific risk for humans was eliminated. Cost/benefit ratio reached 1 : 8. Surveillance programme, including allergic testing, carried out in close cooperation with human medical services continued also during after-elimination decades.

Note: The programme was called “elimination” (to reach zero prevalence) and not “eradication” (to reach complete disease disappearing) due to the fact that M.bovis was exceptionally surviving among human population.

2. Strategic phases

National bovine tuberculosis elimination programme initiated in 1956 lasted 12 years. It was subdivided in 5 basic phases:

experimental phase – 1956-1958,

preparatory phase – 1958-1959,

starting phase – 1959-1960,

main attack phase – 1960-1967 and

final elimination phase – 1968.

Post-elimination period followed from 1969.

3. Experimental phase

- orientation investigations of epizootiological situation in cattle tuberculosis

- testing of different elimination and eradication methods

- testing vaccines against bovine tuberculosis (BCG, M-vaccine)

- testing tuberculin (Old, PPD) and their results’ interpretation

- study of national and international publications on and experience in cattle tuberculosis control

- analyses of bovine tuberculosis impact on human health, animal production, livestock husbandry development, trade, etc. demonstrating catastrophic situation in the country

- first specific postgraduate courses for veterinarians

- meetings of specialists and veterinarians at all levels discussing bovine tuberculosis situation, problems and elimination feasibility

- campaign for convincing veterinarians, farmers, public and government decision-makers on bovine tuberculosis elimination necessity and feasibility

-publication of first monograph on bovine tuberculosis

General Supporting measures:

- consolidation and strengthening of government veterinary services in terms:

of infrastructure, manpower, diagnostic laboratory facilities, tuberculin and specific instruments’ production capacities, material, transport, communication, funds, etc.

- establishment of a new Department of Epizootiology at both Universities of Veterinary Sciences (in Brno and Košice)

- establishment of Epizootiology as a new subject in undergraduate curriculum and as final state exams component.

4. Preparatory phase

- declaration of bovine tuberculosis elimination as the priority for veterinary and livestock services

- government decision on bovine tuberculosis elimination during one cattle population generation to achieve zero prevalence

- issuing ant-tb legislation, directives and instructions for complex preventive and eradication measures and specific surveillance

- establishment of government financial subsidies system complemented by insurance agency contribution

- issuing standards for tb diagnosis (allergic and laboratory) including uniform interpretation of the results

- elaboration of long-term programme with clear cut objectives in all ranches, regions, provinces and at national level

- starting the production of a new PPD tuberculin

- obligatory special training of all government veterinarians starting with provincial and regional Chief Veterinary Officers to assure uniform application of anti-tb method

- production and distribution of anti-tb extension material attracting public, farmers and decision-makers support

- establishment of special surveillance, monitoring, reporting and information system with special forms and data processing (including uniform epizootiological indicators and mapping)

General supporting measures:

. establishment of a network of provincial and regional epizootiologists managed by national chief epizootiologist

- building dense veterinary diagnostic laboratories’ network

- building a central veterinary research institute

- building veterinary sanitation institutes’ network

- establishment of an institute for postgraduate veterinary training

- establishment of an institute for veterinary extension (including printing facilities)

5. Starting phase

- prohibition of anti-tuberculosis vaccination of domestic animals

- allergic testing and registration of all cattle herds and their epizootiological classification according to tests results

- adjustment of anti-tuberculosis methods and plans according to newly discovered situation

- starting all anti-tuberculosis programmes at all levels

- all positive cattle ear-marked without further tuberculin testing

- culling tuberculosis cattle in ranches with low prevalence

- starting massive anti-tuberculosis extension activities

- starting annual anti-tuberculosis postgraduate training of veterinary service regional and provincial chief officers and epizootiologists

- introduction of obligatory pasteurization of cow milk before distribution

- complementing veterinary service material provisions

6. Main attack phase

- executing anti-tuberculosis preventive and eradication programmes at all levels

- temporary adjustment of cow milk and beef production and purchase to assure national planned milk and beef consumption without reducing country cow population: increasing beef production and purchase plans in highly affected regions and provinces giving them chance to cull higher number of tuberculosis cows and simultaneously decreasing them the milk production plan while opposite approach was applied in tuberculosis free or with very low prevalence regions and provinces

- organization of healthy heifers’ (of good genetic quality and usually pregnant to can start new production process) transfers into tuberculosis affected provinces, regions and ranches for the replacement of tuberculosis cattle

- systematic tuberculin testing of all cattle herds (e.g. cows twice a year)

- culling all tuberculin positive cattle with follow-up sanitation – disinfection of infected environment

- systematic postmortem investigations of all slaughtered domestic mammals

- declaration and visible marking (gate tables) of tuberculosis-free ranches

- provision of subsidies for covering losses due to tuberculosis cattle premature elimination (difference between prices) to maintain cattle producers income and standard of living

- intensive bovine tuberculosis surveillance in animal and human populations

- establishment and running tuberculosis isolation ranches/farms for temporary exploitation of selected high milking cows affected by the diseases concentrated from different ranches and regions finalizing the elimination programme

- regulation of anti-tuberculosis programmes to gradually reduce population prevalence and to restrict tuberculosis affected territory

- continue with annual anti-tuberculosis postgraduate training of all regional and provincial chief veterinary officers and epizootiologists

- complex epizootiological and laboratory investigations of all new outbreaks and suspicions in to date tuberculosis free herds

- continuing monitoring and evaluation of anti-tuberculosis programmes’ execution and results with follow-up adjustment when and where necessary.

7. Final elimination phase

- culling of all resting tuberculosis cattle in the country

- abolishment of last tuberculosis isolation ranches/farms

- sanitation – disinfection of the last affected ranches/farms

- final evaluation of tuberculosis elimination programme impact

- biological

- economic

- public health

- social

- final evaluation of cost/benefit of bovine tuberculosis elimination.

Preparation of post-elimination period

- adjustment of the methodology of specific tuberculosis surveillance

- decision on immediate application of radical method for any eventual new cases

- adjustment of information system

- adjustment of veterinary services organization and management

- starting research of tuberculin non-specific reactions

- publication of results and experience.

8. Post-elimination period

- realization of long-term post-elimination surveillance programmes

- continuation of systematic allergic investigations of all cattle herds

- epizootiological and allergic investigations of cattle in critical places and moments (e.g. in quarantines, before and after transfer between ranches)

- complex epizootiological and allergic investigations in cases of bovine tuberculosis suspicion in domestic animals

- complex epidemiological and epizootiological investigations in cases of M. bovis suspicion in humans

- increasing proportion of simultaneous tuberculin tests to distinguish allergic reactions due to M. bovis and M. avium

-strict post-mortem control of all slaughtered cattle

- use of laboratory investigations (incl. typing) in case of bovine tuberculosis suspicion

- application of only radical method when and where new cases of bovine tuberculosis appear

- significant restriction of cattle import (thanks also food self-sufficiency achieved by bovine tuberculosis elimination)- very strict import conditions regarding bovine tuberculosis free status and diagnostic control

- allergic, post-mortem and epizootiological investigations on bovine tuberculosis in other domestic mammals

- continuation of close collaboration between veterinary, public health services (committee for anthropozoonoses, publishing common yearbook called “Surveillance of anthropozoonoses”, etc.) and livestock services (helping regulate national cattle population reproduction process).

More information in http://vaclavkouba.byl.cz/tuberculosis.htm