BISHAJIT DEBNATHID. -113-079-031

Bovine Spongiform Encephalopathy

It was first described in Britain in 1986.

The disease is considered to have spread from Great Britain from export of contaminated Meat-and-Bone-Meal(MBM) in Europe(19 countries reported at least one case of non imported cattle) plus Israel and Japan.

BSE was first recognized in the UK in 1988 , which has the highest yearly incidence of the disease, from its discovery to 2002 more than 180,000 cases were reported.

History of Disease

A fatal prion disease of cattle that affects the nervous system,

resembles or is identical with scrapie of sheep and goats, and is probably transmitted by infected tissue in food called also mad cow disease.

BOVINE SPONGIFORM ENCEPHALOPATHY

The infectious agent in BSE is believed to be a specific type of misfolded protein called a prion.

Prion = Proteinaceous infectious particle Normal Protein: PrPC (C for cellular)

Prion proteins carry the disease between individuals and cause deterioration of the brain.

BSE is a type of transmissible spongiform encephalopathy (TSE)

CAUSATIVE AGENT OF BSE

The natural hosts are cattle.

Some cases have also occurred in antelopes and feline (cats, tiger, puma etc).

A range of other species including mice, pigs, and sheep has been infected experimentally.

Humans are thought to be susceptible (vCJD).

Susceptible species

United Kingdom£3.7 billion total by end of 2001-02In 1996-97

£850 million for compensationPrior to 1996

£288 million on research, surveillance, compensation

Very costly, far reaching disease

Economic Impact

Reasons for emergence

- Feed contaminated with scrapie or unknown BSE - Spontaneous - Changes in feed processing

Maternal transmission - Possible, low risk - Retrospective offspring culling

Current thought - Spread via ingestion of BSE contaminated feed

Animal Transmission

Humans consuming cattle products infected with BSE can develop vCJD

◦ Brain and spinal tissue

Consumption of milk and milk products

Dose required not known

Genetic susceptibility

◦ All human cases have been homozygous for methionine at codon 129 of PrPC

Human Transmission

DEPARTMENT OF MICROBIOLOGY, PRIMEASIA UNIVERSITY

Incubation: 2-8 years

Initial neurological signs◦ Apprehension, fear, easily startled, depressed

Final stages

Excitable, hyperreflexia, hypermetria, ataxia, muscle fasciculation, tremors.

Autonomic dysfunction: reduced rumination, bradycardia and altered heart rhythm

Hyperesthesia or hyperreflexia.

Incubation Period and clinical Sign

Terminal state

◦ Decreased rumination◦ Loss of body weight and condition, despite good appetite

There is no treatment for BSE

Affected herds

◦ 2-3% morbidity◦ 100% mortality

Visible Sign and Treatment

The BSE testing protocol calls for an initial rapid test called an Enzyme-Linked Immunosorbent Assay (ELISA).

If the ELISA test is inconclusive, samples are sent for confirmatory testing to the National Veterinary Services Laboratories (NVSL).

An immunohistochemistry test is conducted at NVSL and, concurrently, an OIE-approved Western Blot is conducted at the National Animal Disease Center (NADC).

These tests are designed to detect the presence of BSE-specific abnormal prion protein in the brain tissue.

DIAGNOSIS

June 24, 2005

- New BSE confirmatory testing protocol

IHC & Western Blot

confirmatory tests

Positive result on either test considered positive for BSE

“Inconclusive” BSE rapid screening tests.

Post Mortem Tests for BSE

No effective treatment or vaccine

Surveillance program

Blood/plasma donation restrictions

USDA bans importation of ruminants from countries with BSE.

Persons who have traveled or resided in the U.K. for 3 or more cumulative months from 1980 to 1996.

Vaccination/Prevention

Bovine spongiform encephalopathy (BSE), commonly known as mad cow disease, is a fatal neurodegenerative disease (encephalopathy) in cattle that causes a spongy degeneration in the brain and spinal cord.

The infectious agent, although most highly concentrated in nervous tissue, can be found in virtually all tissues throughout the body, including blood.

CONCLUSION

THANK YOU

DEPARTMENT OF MICROBIOLOGY, PRIMEASIA UNIVERSITY