A century ago there were many animal health problems, which have largely been resolved, except, they have been replaced by a new set caused by different conditions. Anthrax has been eradicated for example, and rabies in the UK and most of Europe
Many animals are now kept in intensive conditions, and perhaps a combination of this and other factors has been implicated in some recent outbreaks of animal disease, some of which appear to have also endangered human populations.
To briefly note some of these problems, with the apparent causes:-
- BSE (bovine spongiform encephalitis) appears to be implicated in CJD (Creuzfeld-Jacob disease) which affects humans. Both are degenerative diseases of the central nervous system (and scrapie in sheep may in fact be the pre-cursor of this) and the condition is caused by a virus which has a very long incubation time before any symptoms are apparent. It is thought that ground-up remains of infected sheep were added to cattle feed. When these apparently healthy cattle were slaughtered, and some marrow, spinal or brain tissues from these animals were used for human food products, leading to the CJD cases. It is now believed that these food-chains have been broken in two ways, as animal protein is no longer used in cattle food, and marrow and brain tissues are no longer used in human foods
- Foot and Mouth disease. This is a contagious disease which affects pigs, cattle and sheep (but seldom humans). In a recent outbreak in the UK many millions of animals were slaughtered. For any farm which had an outbreak, all animals on all adjoining farms were slaughtered, and there were strict regulations about access to land, disinfection of vehicles in the affected areas, etc. and the disease was finally brought under control. The causes are not really known, but it appears that the disease was spread by unnecessary stock movements, some of which were intended to cheat the subsidy systems. The disease is endemic in many parts of the world, where it is thought of as the equivalent to tonsillitis - the animal is quite ill, but then recovers.
- Bovine Tuberculosis. This is a cause for concern in some parts of the UK. The government proposes a cull of all badgers in these areas, as a similar form of TB is endemic in badgers, and it is thought that they infect the cattle.
- Swine Vesicular disease. This appears to break out every year, with several herds of pigs culled, and this seems to be kept under control
- Chicken influenzas. Some influenzas of chicken are infectious for humans, and there seem to be outbreaks of new strains of the virus every year, perhaps originating in the far east
- E. coli. There seem to be regular E. coli outbreaks, which can be very dangerous for humans if large quantities enter the food chain. E. coli is an intestinal bacterium which is found in nearly all species, and poor hygiene at the slaughterhouses and butchers is often blamed for this
- Mastitis. This is an infection of cows teats which is widespread, and which is treated with direct injections of antibiotics, which inevitably are then present in small quantities in milk and milk products.
- Calves and cows are now separated soon after birth. The cows give milk until the next calf is born, often without a pause. Cows are almost invariably fertilised by artificial insemination.
- Salmonella. There have been several outbreaks of this disease in recent years, apparently due to poor hygiene during the handling of food. Often it is caused by reheating 'once-cooked' foodstuffs.