US: Cow with atypical BSE detected, limited feed contamination concern

By Aerin Einstein-Curtis

- Last updated on GMT

© GettyImages/ jotily
© GettyImages/ jotily
The USDA has confirmed that a cow has been found to have atypical Bovine Spongiform Encephalopathy.

The USDA's Animal and Plant Health Inspection Service (APHIS) said yesterday [August 29] that the cow was positive for an atypical H-type case of the cattle neurologic disease Bovine Spongiform Encephalopathy (BSE​).

The six-year-old, mixed-breed cow was located in Florida, the department said. It did not enter slaughter channels and did not present a risk to the food supply or to human health in the US.

The diseased animal was detected following routine testing carried out at slaughter, a spokesperson with the APHIS told FeedNavigator. “This is atypical, so it's spontaneous and there's no connection to any other cows with the disease or to feed,”​ she added. 

Colorado State University’s veterinary diagnostic laboratory initially tested the cow during a routine surveillance of cattle that have been designated “unsuitable for slaughter,”​ the USDA said.

More information on the case is currently being gathered by APHIS and veterinary officials in Florida, the department added.

Feed concerns and atypical BSE

There are two forms of BSE – classical and atypical – and neither is contagious, said the USDA.

Classical BSE was the form found initially, often in the UK, starting in the 1980s, the department said. In the classical form of the disease, the primary source of infection was feed contaminated with an infectious prion agent – like meat and bone meal that included proteins generated from the rendering of infected cattle.

Since 1997, US Food and Drug Administration (FDA) regulations have stopped the use of mammalian protein in feed for cattle and other ruminants, the USDA said. Use of high-risk tissue materials in any animal feed have been prohibited since 2009.

The classical BSE form also is the type of the disease that has been linked to Creutzfeldt-Jakob disease in people, the department said.

However, atypical BSE has a different presentation, said the department. It usually occurs in older cows and appears to happen spontaneously and rarely in all cattle populations.

“No other cows displayed symptoms because it's an isolated spontaneous case,”​ the spokesperson added. “As part of the epidemiological investigation, we look at the offspring of animals diagnosed with atypical BSE as well as animals born at the same time in the same location as the affected animal.”

The disease appears to stem from a spontaneous change in the prion proteins in older cattle, the USDA said. However, the process and conditions that cause the prions to alter are not completely understood.

The World Organization for Animal Health (OIE) considers the US to have a negligible risk for BSE, and atypical BSE cases do not alter official BSE risk status recognition as the form of the disease is thought to happen randomly and rarely in all cattle populations.

The diagnosis of the cow from Florida is not expected to change the US’s negligible risk status, or lead to any trade concerns, the department added.

To prevent future occurrences of classical BSE the US has designed a set of interlocking safeguards, said the USDA. These include removing all specified risk materials – the parts of an animal that would carry the disease if the animal was sick – from all animals taken for slaughter.

Additionally, there is a feed ban in place designed to protect cattle from the disease, the department said. There also remains an ongoing BSE surveillance program, which found the current cow, that enables the USDA to find the disease if it presents in the US cattle herd.

This is the sixth cow with BSE found in the US, said the department. The first case, found in 2003, was a cow with classical BSE that had been imported from Canada and was born before feed bans on high-risk material were started. The other four have all had atypical – either H- or L-type – BSE.

No relation has been reported between the finding of this cow, and one reported in July 2017​ in Alabama.    

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1 comment


Posted by Terry S. Singeltary Sr.,

''Atypical BSE is different, and it generally occurs in older cattle, usually 8 years of age or greater. It seems to arise rarely and spontaneously in all cattle populations.''
''The primary source of infection for classical BSE is feed contaminated with the infectious prion agent, such as meat-and-bone meal containing protein derived from rendered infected cattle. Regulations from the Food and Drug Administration (FDA) have prohibited the inclusion of mammalian protein in feed for cattle and other ruminants since 1997 and have also prohibited high risk tissue materials in all animal feed since 2009.''


P98 The agent of H-type bovine spongiform encephalopathy associated with E211K prion protein polymorphism transmits after oronasal challenge

Greenlee JJ (1), Moore SJ (1), and West Greenlee MH (2)

(1) United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Virus and Prion Research Unit, Ames, IA, United States (2) Department of Biomedical Sciences, Iowa State University College of Veterinary Medicine, Ames, IA, United States.

In 2006, a case of H-type bovine spongiform encephalopathy (BSE) was reported in a cow with a previously unreported prion protein polymorphism (E211K).

The E211K polymorphism is heritable and homologous to the E200K mutation in humans that is the most frequent PRNP mutation associated with familial Creutzfeldt-Jakob disease.

Although the prevalence of the E211K polymorphism is low, cattle carrying the K211 allele develop H-type BSE with a rapid onset after experimental inoculation by the intracranial route.

The purpose of this study was to investigate whether the agents of H-type BSE or H-type BSE associated with the E211K polymorphism transmit to wild type cattle or cattle with the K211 allele after oronasal exposure.

Wild type (EE211) or heterozygous (EK211) cattle were oronasally inoculated with either H-type BSE from the 2004 US Htype BSE case (n=3) or from the 2006 US H-type case associated with the E211K polymorphism (n=4) using 10% w/v brain homogenates.

Cattle were observed daily throughout the course of the experiment for the development of clinical signs.

At approximately 50 months post-inoculation, one steer (EK211 inoculated with E211K associated H-BSE) developed clinical signs including inattentiveness, loss of body condition, weakness, ataxia, and muscle fasciculations and was euthanized.

Enzyme immunoassay confirmed that abundant misfolded protein was present in the brainstem, and immunohistochemistry demonstrated PrPSc throughout the brain.

Western blot analysis of brain tissue from the clinically affected steer was consistent with the E211K H-type BSE inoculum.

With the experiment currently at 55 months post-inoculation, no other cattle in this study have developed clinical signs suggestive of prion disease.

This study demonstrates that the H-type BSE agent is transmissible by the oronasal route.

These results reinforce the need for ongoing surveillance for classical and atypical BSE to minimize the risk of potentially infectious tissues entering the animal or human food chains.



USDA Announces Atypical Bovine Spongiform Encephalopathy Detection USDA 08/29/2018 10:00 AM EDT

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