In the UK, there are hundreds of bovine diseases (diseasesin cattle), many of which are zoonotic meaning that they can be passed on tohumans. Therefore, a large proportion of these can have serious effects on bothcows and humans. In this essay, I will discuss a few of the more commonly knowndiseases such as Tuberculosis, “mad cow disease”, leptospirosis, andbrucellosis which can all be contracted by humans. In addition, I will talkabout “foot and mouth disease” which has been a major problem in the UK in thepast. “Mad cow disease”, which is referred to in the medical worldas Bovine spongiform encephalopathy (BSE), is a fatalneurodegenerative disease that affects the central nervous system in cowsalthough the disease can mutate, into a strain known as VariantCreutzfeldt-Jakob disease (vCJD), and spread into humans. Humans most frequentlycontract the disease through consuming infected meat and it causes a spongiformdegeneration of the brain and spinal cord. The disease is causedby a misfolded protein, known as prion.
The problem is that prions areextremely stable and they are not destroyed during freezing or during cooking,as they only denature at extremely high temperatures, so any infected meat thatan individual may consume may give them the disease. Prions are not living sothey cannot be killed by normal disinfectants and the body does not produce anormal immune response. According to scientists BSE can arise in animals thatcarry a specific allele which can cause normal protein molecules to contortthemselves from a helical arrangement into beta pleated sheets, which is the disease-causingshape for the particular protein. As the number of these deformed proteinsincrease, the degeneration process increases exponentially, eventually leadingto microscopic holes in the brain known as plaque fibres.
It is these holesthat lead to the degeneration of the physical and mental abilities of theinfected individual. The transmission can occur when animals come into contactwith infected tissue as BSE is not contagious and therefore cannot betransmitted from animal to animal, only through consumption of infected tissuein food. In the brain of a cow these proteins cause prion proteins to deforminto their infectious state. It is thought that BSE first arose in Britishherds due to cows being fed the processed animal remains ofsheep infected with scrapie, a closely related brain-wasting disease.
Symptoms are not seen immediately due to the extremely longincubation period of the disease but the WHO (world healthorganisation) says that infected individuals usually experience “depression,apathy or anxiety”. They also report victims have difficulty walking andcontrolling their limbs as the disease progresses. By the time of death victimsare “completely immobile and mute.” In cattle, the infected animals willgenerally have been seen to become increasingly aggressive, as their nervoussystem deteriorates and they lose control of their movement. The Milkproduction of the cows may also drop, with some become increasingly skinny andlethargic. The first confirmed case in Britainwas in 1986 and the last major outbreak in the UK was in1992.
during the lastoutbreak it is estimated that 180 000 cows were affected and killed andaltogether 4.4 million cows were killed. 156 people died in the 1990s asa result of contracting the variant of BSE. This number has risen to 177 at thepresent day. The outbreak did not just affect animals and it had a dramaticeffect on the sale of beef which fell by 40% with household consumption down by25%.
Financially it is estimated that the outbreak cost the economy around £800million.