Pathogen of the Month - 2019 Archive
January pathogen of the month:
Foot and Mouth Disease
What is it?
Foot-and-mouth disease (FMD) is a highly communicable viral disease caused by an Aphthovirus of the family Picornaviridae.
It primarily affects cloven-hooved animals of the order Artiodactyla. Livestock hosts include cattle, pigs, sheep, goats, and experimental infections in alpacas and llamas. FMD virus has also been reported in more than 70 species of wild artiodactyls, including bison, giraffes, Indian elephants, and several species of deer and antelope.
The disease is characterized by fever and vesicles in the mouth and on the muzzle, teats, and feet and is spread through direct contact or aerosolized virus via respiratory secretions, milk, semen, and ingestion of feed from infected animals.
In a susceptible population, morbidity reaches 100% with rare fatalities except in young animals. FMD was once distributed worldwide but has been eradicated in some regions, including North America and Western Europe. Outbreaks can severely disrupt livestock production and require significant resources to control, as in the 2001 UK outbreak.
The first indications of FMD were recorded in 16th century Venice. The affected animals refused their feed, the oral mucosa showed redness and the animals had vesicles in the oral cavity and on their feet. Today it is considered one of the most important diseases of cloven-hoofed animals. The disease has been present in almost every part of the world where livestock are kept.
Mode of transmission:
Animals pick up the virus either by direct contact with an infected animal or by contact with foodstuffs or other things which have been contaminated by such an animal. They may also become infected by eating or coming into contact with some part of an infected carcass.
Are there preventative steps?
FMD is one of the most difficult animal infections to control. Because the disease occurs in many parts of the world, there is always a chance of its accidental introduction into an unaffected country.
FMD outbreaks are usually controlled by quarantines and movement restrictions, euthanasia of affected and in-contact animals, and cleansing and disinfection of affected premises, equipment and vehicles.
Rodents and other vectors may be killed to prevent them from mechanically disseminating the virus. Vaccination can be used to reduce the spread of FMD or protect specific animals. Vaccines are also used in endemic regions to protect animals from clinical disease. FMDV vaccines must closely match the serotype and strain of the infecting strain.
What is the current status?
In recent weeks, foot and mouth disease outbreaks have been reported in several areas of Asia. In India, The Department of Animal Husbandry, Veterinary and Dairy Development reported that 26 mithuns had died of foot and mouth disease in Papum Pare district since June. Officials said 2,957 animals had been either treated or vaccinated in the district.
A new outbreak was also reported among pigs in Hanoi's Ba Vi district. Local reports say 261 pigs belonging to 19 households in 6 communes of the district were affected by the disease. The Ministry of Agriculture and Rural Development's Department of Animal Health asked provincial authorities to kill the affected pigs. Local veterinary units initiated vaccinations of cattle in the area.
An outbreak was also recently confirmed in Israel involving a herd of recently vaccinated heifers.
What is CEEZAD doing?
CEEZAD is developing diagnostic and detection tools for FMD including a mutli-antigen print immunoassay test for expressed diagnostics of antibodies to FMDV. It is also developing an assay for detection of FMD virus at the site of infections (point of need, or PON, diagnostics).
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Sources: Merck Veterinary Manual, Biomed Central, The Cattle Site; CEEZAD
February and March pathogen of the month:
Chronic Wasting Disease
What is it? Chronic Wasting Disease is a prion disease of cervids (deer, elk, reindeer, moose). Prion diseases are a class of diseases caused by “prions,” which are infectious misfolded proteins that lead to neuro-degenerative changes in the brain. They are usually rapidly progressive and fatal.
CWD was first identified in captive deer in a research facility in the late 1960s in Fort Collins, Colorado and in wild deer in 1981.
By the 1990s, it had been reported in surrounding areas in northern Colorado and southern Wyoming. Once CWD is established in an area, there is a risk that it can remain for a long time in the environment. That means the affected areas are likely to continue to expand over time.
There have been no reports of CWD in humans. Animal studies suggest a potential for risk for non-human primates (such as monkeys); concerns have been raised about the potential for a risk to humans.
Mode of transmission.
Scientists believe CWD proteins (prions) likely spread between animals through body fluids like feces, saliva, blood, or urine, either through direct contact or indirectly through environmental contamination of soil, food or water.
Once introduced into an area or farm, the CWD protein is contagious within deer and elk populations and can spread rather quickly. According to the CDC, CWD prions can remain in the environment for years, so other animals can contract CWD from the environment even after an infected deer or elk has died or moved away.
What is the current status?
The Centers For Disease Control reports that Chronic Wasting Disease has been identified in either farmed or wild cervids in 24 states. That total includes 27 Kansas counties, most of them in the western part of the state but ranging eastward as far as Jewell County in the state’s north-central region. Officials of the Kansas Cervid Breeders Association note, however, that the actual instance of CWD in the state is low, equating to 1 in 200,000 deer.