Bovine Spongiform Encephalopathy

Comprehensive Guide to Bovine Spongiform Encephalopathy (BSE)

According to abbreviationfinder, BSE stands for bovine spongiform encephalopathy. It is a chronic, non-febrile and fatal disease; characterized by a long incubation period followed by fatal progressive degeneration of the central nervous system of adult bovines and transmitted to humans by ingestion of parts of the brain of infected bovines.

Synonymy

Bovine Spongiform Encephalopathy, Mad Cow Disease, Mad Cow Disease

History

BSE was recognized as a new animal TSE as a result of the “mad cow” epidemic that occurred in England during the period 1989-92, although the first cases were detected in 1986. It is estimated that during this epidemic some 200,000 cows (mainly Holstein Friesian -type adult dairy cows) succumbed to the disease and another 4,500,000 (asymptomatic under 30 months of age) were slaughtered as an epidemiological prevention measure. It has also been mentioned that more than 1,000,000 cows were infected, but that most did not develop the disease because they were slaughtered for human consumption between 2 and 3 years of age.

Etiology

BSE is caused by an unconventional agent called Prion, an infectious protein particle, smaller than viruses. This agent is extremely resistant to heat, radiation and many chemical agents. It is postulated that the causal agent of BSE is the same one that causes sheep scrapie, which has managed to adapt to cattle.

Transmission source

The prion is transmitted when cattle consume food containing meat and bone meal, made with tissues from infected ruminants; There is no evidence that it is transmitted horizontally by direct contact, and vertical transmission from infected mothers to their offspring has no epidemiological significance.

The main tissues capable of transmitting the disease known as specified risk materials (SRM) are those tissues that represent a high risk for humans and animals, because they have been exposed to the prion and because at some point during the incubation period of the disease, they become infected; among them are:

  • brain.
  • spinal cord.
  • Eye.
  • trigeminal ganglion.
  • Dorsal root ganglion.
  • ileum.
  • tonsils

The incubation period of the disease varies between 2 and 8 years.

Countries BSE has been diagnosed

Apart from the United Kingdom, it has been found in cattle from the European countries of Germany, Austria, Belgium, Denmark, Slovakia, Slovenia, Spain, Finland, France, Greece, Italy, Luxembourg, Liechtenstein, the Netherlands, Poland, Portugal, Republic of from Czech, Republic of Ireland, Switzerland, Germany; as well as in animals from Israel, Japan, Canada, and in the United States.

Symptoms

Cattle¬† affected are nervous, trembling, wobbly, apprehensive and with changes in behavior, hence the name “mad cows”. Nervous behavior is seen in most affected cattle and is interpreted as the animal becoming isolated from the rest of the herd, resisting entering the milking parlor and being milked. The first locomotor signs are small changes in the movements of the hindquarters and difficulty in getting up from a normal position, which can be confused with hypomagnesemia and nervous ketosis. Locomotor changes are translated by staggering walk, short strides and clumsiness when turning. The main neurological signs of BSE are apprehension (fear or nervousness), ataxia (incoordination when walking), and hyperaesthesia (excessive and painful sensitivity). Animals with any or a combination of these signs for more than one month should be considered as suspected cases of BSE. We can also find excessive salivation, decreased rumination accompanied by bradycardia (decreased heart rate) and arrhythmia (irregularity and inequality in heart rate), as well as trismus (teeth grinding).

Diagnosis

Currently, the diagnosis is made after the death of the animal, so the disease is confirmed in the laboratory through the use of rapid tests such as lateral flow immunochromatography of the brain stem and its confirmation with Western blot techniques. and immunohistochemistry; likewise, the differential diagnosis is important to rule it out from a series of diseases with a similar pathology.

Differential Diagnosis

Rage

Listeriosis

thromboembolic meningoencephalitis

Aujeszky’s disease

Plant and chemical poisoning

Mineral deficiencies or downer cow syndrome

Prevention and control

So far neither vaccines nor treatments have been developed to prevent it, so control is limited to restricting the movement of ruminants and their products from affected countries.

Bovine Spongiform Encephalopathy

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