Please enable JavaScript.
Coggle requires JavaScript to display documents.
Johnes (paratuberculosis) - Coggle Diagram
Johnes (paratuberculosis)
chronic enteritis of adult cattle and sheep caused by mycobacterium avian subspecies paratuberculosis (MAP)
-->
MAP is a Bacteria, an obligate intracellular bacteria
MAP has a thick waxy cell wall which renders the organism resistant to many disinfectant
MAP is Notafiable in Northern Ireland
After ingestion MAP enters macrophages via the ‘M’ cells in the Peyer’s patches. This infection of macrophages persists for years without any response from the hosts immune system resulting in a long Incubation period (from infection to immune response and clinical signs) which leads to difficulty in detecting infected animals early in the course of disease.
can last for years in the environment. Resistant to some disinfectants and can last over a year in faeces, slurry, water courses and pasture
clinical signs
progressive weight loss
chronic diarrhoea
long incubation period - clinical signs not usually apparent until
3-5 years old
onset often follows stressful event e.g. calving, sale, transportation
no fever and animal maintains a good appetite until the terminal stages
clinical signs may continue for several months with cow/bull becoming emaciated, then being culled for economic/welfare reasons
submandibular oedema
may lead to death
signs of endemic infection: infertility, decreased milk production, increased culling, increased mastitis and SCC cases in the cows
aetiology
intrauterine infection of the developing calf in heavily-infected dams
transmitted to young calves
by ingestion of the organism in
colostrum
faecal contamination of food/surface water/water troughs/cow teats
infected animals may shed organisms in faeces for over a year before clinical signs appear
Risk factors
Open Herds - buying in cattle, Shared grazing fields with neighbouring farms, Mixed grazing with other species, Hired bulls (or borrowing bulls from other farms), Hired or borrowed slurry tankers or spreading your neighbours slurry on your fields
diagnosis
no single reliable test for confirming Johne's disease during early stages of disease
low sensitivity
blood tests to detect antibodies to crude M.paratuberculosis antigen, not all cases have a detectable antibody response
diagnosis best done using a combination of serology and faecal examination for the causative organism
control
difficult due to long incubation period and shedding before clinical signs and poor detection in early stages of disease
identification and removal of infected animals
blood testing +/- faecal examination may be done every 6-12 months with slaughter of positive cases
practical measures to limit herd losses
rapid culling of diseased animals
minimise faecal contamination of food, water and pasture
e.g. by raising feed and water troughs, strip grazing, use of mains/piped water rather than surface/pond water, avoid spreading yard manure on pasture and maintain good hygiene in buildings/yards and calving boxes
separate newborn calves from dams at birth and rear by bucket with artificial colostrum/milk
do not feed waste milk to calves
do not raise calves from known infected dams as breeding replacements
re-stock only from accredited herds, esp. bulls
rabbits and deer play a role in disease spread, but may be difficult to control
biosecurity measures if herd uninfected
Maintain a closed herd and high biosecurity or if buying animals use Johnes accredited herds
Keep cows and their environment clean and free from faecal contamination, especially during the calving period and the first three months of life
Do not graze youngstock on ground that has had dung or slurry spread on it until at least a year after application
Avoid co-grazing with other livestock that can be infected with Johne’s disease (sheep, goats, camelids)
Monitor for disease regularly and consider joining a Johne’s disease screening and eradication programme, such as CHeCS
vaccination
Inoculation is given into the brisket area of calves less than one month old (preferably less than one week) producing considerable local reaction. Vaccinated herds/flocks have much reduced clinical cases and losses but Johne's disease will not be eradicated. Vaccination may be the most cost-effective option for commercial beef herds breeding their own replacements and experiencing considerable loses from Johne's disease.
interferes with the interpretation of the tuberculin skin test