Following info from 'Mycobacterium bovis Infection in Animals and Humans', 2nd edition, 2006, ISBN 0-81380919-3. The book is a series of articles written by different 'experts'. Where refs given in brackets these are source documents referred to.
 
GENERAL
 
BTB is a controlled disease because of its zoonotic potential. In reality control is difficult because now there is a rapid increase in the movement of people (globalization); environmental change; expansion of the human population; destruction of animal habitats; changes in animal husbandry (Thiermann 2004).
 
There is STILL only a limited knowledge of pathogens available for M bovis. DNA composition has been determined but no specific sequence has been identified that codes for virulence. Many individuals can be infected with tubercle bacilli yet only a % (not known) develop progressive disease and die.
 
Test and slaughter policy is claimed to have been successful in most of Europe (excl. GB and Ireland), Australia, Canada and USA. However, this has often only been possible by complete depopulation of herds and stringent movement controls. The few cost benefit analyses have failed to provide favourable results. In some cases negative results make control strategies difficult to justify.
 
Page 142 Suggests avian TB is serious disease and difficult to treat! We are told disease mild in cattle, hence used as the control for skin test in UK. It is rife in UK with many cattle responding - total numbers not retained!
 
Not all tuberculosis lesions found in cattle (or other species) are M.bovis.
 
60% of human population live in countries where cattle undergo no control for bTB (Cosivi et al).
 
Measurements for determining positive reactors very from any reaction considered positive in some countries to up to 5mm tolerance in others.
 
'Survival of bovine tuberculosis mycobacteria in pasture spoils' by VN Kislenko - Russian study indicated bacteria viable in 0-2cm, layer for up to 23 months.
 
OIE give 0.2% max. for TB free status.
 
Interesting UK - diagrams pages 106 (no. of cattle served by each Animal Health division shown for each region. Page 109 testing intervals - shorter ones where most breakdowns are and ties in with areas with largest nos. of cattle.
 
Eradication involves continual surveillance with ever stringent measures to keep status.
 
Also found in fur seals in Australia, Argentina, UK, Uruguay and New Zealand.
 
SKIN TEST Recently infected cattle fail to react to the skin test (takes 30 days before they react). Test also fails if there is reduced potency of tuberculin, not sufficient quantity injected; immunosuppression/anergy/physiological state of animal; operator errors. Cattle can become desensitized to test! Few studies and most of these have not used cattle in natural surroundings. 'Test claimed to be the most reliable and practical methods (albeit tentative)'! Animals infected with M bovis are allergic to the proteins contained in tuberculin and develop characteristic delayed-type hypersensitivity reactions when exposed to the proteins. Injecting tuberculin deep into the skin 'usually' elicits localised inflammation and swelling in the affected animal. However, sensitivity and specificity depend on field conditions prevalence of infection and other factors! BCG (Bacile Calmette-Guerin vaccine does not completely prevent infection.
 
In UK incidents of bTB increased ten fold between 1979 and 2000!
 
According to Cosivi et al (Zoonotic tuberculosis due to M.bovis in developing countries) approximately 85% of cattle and 82% of human populations are in areas where bTB is either partially or not controlled at all.
 
Cattle can be successfully treated (not allowed in many countries) with anti Tb drug isonicotinic acid hydrazide.
 
Despite the fact that cattle are considered to be natural hosts, pathogen has an exceptionally wide host base with most warm blooded animals being susceptible to infection. Other common spillover hosts include moles, voles, hedgehogs, rodents
 
VACCINATION
Ideal vaccination will give long lasting protective immunity (preferably soon after administration) without causing disease in the recipient or subsequent contacts. Vaccination should;
1. allow detection of infection versus immunised individuals without interfering with available diagnostic tests.
2. be cost effective and easy to produce in quantities.
3. be easy to store and transport, preserving its immuno-biological properties under different environmental conditions,
4. be easy to administer to large groups, ideally in a single dose without causing side effects.
5. be safe.
6. have therapeutic properties.
7. be compatible with other vaccinations (not interfering with the effectiveness and safety of other vaccines).
 
 
 
OVERSEAS (interestingly there is only one ref to France - and not helpful! One does wonder why info is not available from this country!). Where control is most needed (ie where risks are higher) costs, political problems etc are preventing action! It is clear that even in areas where it is rife the vast majority of cattle (and people) do not become clinically ill or die from the disease (AIDs is an issue and is certainly responsible for an increase in all forms of TB).
 
bTB eradication programmes have had little success in countries in which transmission of of M. bovis from domestic to wild animals has led to the emergence of wildlife reservoirs of this disease. As a consequence, in many countries, persistence of bTB in cattle populations has been attributed to reservoirs of the disease in wildlife and feral animals. However, only a small proportion act as maintenance hosts (ie sustain the disease) eg bush tail possums (NZ), badger (UK, Ireland), bison (N America), deer (N America), buffalo (Africa). PROTECTION OF CATTLE AGAINST INFECTION VIA VACCINATION IS AN IMPORTANT CONTROL STRATEGY WHERE WILDLIFE RESERVOIRS PERSIST.
 
Data from WHO revealed more than 95% o the estimated 8 million new TB cases are in developing world and only 10% are caused by M.bovis (Economics of Bovine Tuberculosis, J Zinstagg, E Schelling, F Roth and R Zuzwala). Considered imperative back in 2006 that cheaper control methods are developed! Whilst the disease is allowed to persist in some countries, in a globalised world, with falling trade barriers, there will always be the risk of spread to disease-free zones.
 
AFRICA
After AIDs TB (human form) is responsible for more deaths each year than any other single disease. 50% of new TB cases now attributed to AIDs. However, it is unknown what % bTB plays in the rising TB epidemic in Africa. Studies in Malawi show high rates of bTB are not necessarily matched by a concomitant prevalence of TB (human form). Livestock industry for most of sub-sahara Africa is significantly underproductive compared to S Africa, Asia and Europe because of all kinds of disease, including bTB. Minimal control measures in place for 35/50 African countries reporting to the OIE. Not been able to eliminate or effectively control disease; lack of co-ordinating /surveillance data. Not reporting for political, social and economic motives. Thought to be widely distributed and at high prevalence in some animal populations (spillover hosts include baboon, lion, cheetah, uda, leopard, warthog, honey badger, genet.. Also affects small ruminants, camels and many other wildlife species. Nigeria has test and slaughter policy but limited implementation. Endemic in most of eastern and southern Africa.
 
In contrast, S Africa's livestock productivity is comparable with developed countries. However, buffalo act as wildlife reservoir. General opinion in medical circles is that M.bovis infection as a cause of TB is of negligible significance as a zoonotic disease (Bovine tuberculosis programme in S Africa: the impact of M. bovis infected wild species by N Kriek).
 
Cattle are houses closer to humans and so greater risk (zoonosis). Eating habits exacerbate any transmission of bTB (eg raw/undercooked meat consumed and milk not heat treated).
 
AUSTRALIA
Eradicated only by complete depopulation of herds infected. Restocking only with clean animals after a waiting period. Incidents involving wild boar.
 
CANADA
One of 1st countries in world to commence programme to deal with disease (1897). Free testing (caudal fold skin test), later done via meat inspections. Found in bison, cervids. Depopulation with vacant periods before re-stocking plus extensive disinfection. Now any meat with TB lesions traced back to farm and herds depopulated (also all livestock from that farm killed and restrictions placed on neighboring farms. Still found in bison (1980's emerged). . The once enormous herds of plain bison now reduced to a handful in private ownership. Wood bison reduced to small areas of woods. Now endemic (47%) free roaming bison herds in and around Wood Buffalo Nature Park (important for tourism/hunting). In view of its location considered low risk to cattle, although expected risk will increase! Now buffer zones around wildlife parks. Also some evidence in wild elk and deer but rates fall in these animals when cattle controlled. Cattle mainly free of TB except in Manitoba but the wildlife reserves of disease threaten to reintroduce to cattle.
 
CHINA
Many years of prevention and treat (this interesting but very little info) campaign. Still occurs spasmodically among cattle populations. Depopulation of infected herds.
 
INDIA
Rare until 1916. Various possible (unconfirmed) reasons for this including; relatively high resistance of indigenous breed, low virulence of infective organisms or natural limitation of spread of disease, resulting from husbandry practices of cattle in India. In one study it was found that a large % of animals that test positive for TB do not develop a rapidly progressive form of the disease. Lesions in Indian cattle generally localized and restricted to a few lymph nodes. (Of course this may be the case in other countries too but all reactors slaughtered without investigation!)
 
TB test and segregation of reactors, with slaughter only for those showing clinical signs of disease. Eradication plan to build up clean herd (presumably using this method!?) from 20% to nil in 2.5 years. Does not seem to have been met! It states the reason for choosing a test and segregation policy may be that a high % of TB positive animals exist in several areas - wholesale destruction may reduce number of milk animals and working bullocks used as power for agricultural operations - thus unduly affecting economy of Indian agriculture! Another reason put forward is public opinion against destroying animals that look healthy! (The Status of M.Bovis in India by R Verma).
 
RUSSIA
Free of TB. Control in 1959. Strict controls, slaughter of positives and also calves of infected dams. All areas disinfected. 10-15cm soil removed, sub soil disinfected.
 
NEW ZEALAND
Incidents involving wild boar
 
USA
It took USA 50 years to eliminate disease from 'most' herds. Programme began 1917. It states (pg 90) 'although public and animal health were synergistic motivations for the US, the public health benefits were more from the result of pasteurisation than of reduction in the prevalence of TB in cattle. 1901-1937 M. bovis responsible for 158 (13%) of 1200 human cases of TB in US. Pasteurisation commenced 1908 and nearly eliminated human illness caused by M. bovis! 1954-68 responsible for just 6 (0.2%) of 2086 human cases of TB.Since 1917 estimated prevalence of infected cattle declined from 5% to about 0.001%. Programme focussed on individual animal testing from 1917 - 1959 (prevalence estimated as number of reactors detected by number of cattle tested in a given year). Since 1959 surveillance shifted to greater reliance on slaughterhouse inspection of carcasses. Trend is downwards.
 
Page 213 gives example of bull that died. It had extensive lesions when PM'd yet had tested negative in all skin tests. Its herd subsequently depopulated.
 
Incidents involving wild boar (N America).
 
LATIN AMERICA AND CARIBBEAN
24% of cattle population in the region is only partly or not controlled at all.
 
EUROPE
FRANCE
Other than the outbreaks in South of France this year can't find much!
 
ITALY
Control enforced in 1954 - compulsory slaughter of bovines showing clinical signs. Initially voluntary but since 1977 compulsary for every breeding herd, except specialised an separated fattening units. 1995-2001 annual herd prevalence dropped frtom 1.3% to 0.63%. Annual single intradermal skin test (ie no avium comparison). Slaughter of reactors within 30 days, part compensated by govt. In 2003 herd prevalence 0.98% (but 5.94% in Sicilia!). 4775000 cattle submitted to periodic controls, 6573 found positive (half of these in Sicilia!). A few cases (considered insignificant) in buffalo (of 319,000, 109 positive).
 
GERMANY
In wild board reported 1930's =- sporadic cases where there are many wild boar or feral pig populations,
 
IRELAND no ref in book but see http://www.agriculture.gov.ie/media/migration/animalhealthwelfare/disease/tuberculosistbandbrucellosis/publicationsleaflets/Bovi...
 
NETHERLANDS
Introduced pasteurisation in 1940 when rates of bTB declined sharply.
 
SWEDEN
 
in 1930's around 30% of slaughtered cattle had lesions. (130 - 40 control intensified and in 1958 was one of 1st countries in the world declared OTF. Sporadic cases occurred since. The compulsory skin test was abolished in 1970, now based only on meat inspections. Only wildlife infection recorded is in 2 cases in 1940 - both in free living moose. Around 10 cases reported annually in humans but these mainly in elderly (latent infection) or immigrants. However, in 1991 diagnosed in farmed deer! 13 farms - voluntary control programme, based on TB testing, implemented July 1994, becoming compulsory in 2003. Deer farming in Sweden is popuylar, increasing in 1990's with government subsidies to promote alternative use of farmland. Deer farms with TB depopulated. As at 2005 there were 239 empty, depopulated herds and 85% had TB free status. Interestingly not spread to cattle so status not affected (so other animals can have disease and status still TB free!).
 
CENTRAL EUROPE (Bosnia, Herzegovina, Croatia, Czech Rep, Hungary, Poland, Slovakia, Slovenia)
1953 - 80 eliminated.
Czech - 2004 declared TB free. In these countries all reactors to single intradermal skin test are tested again 6 weeks later. Animals repeatedly positive are slaughtered.