my presentation on johnes disease

7/28/2019 My Presentation on Johnes Disease

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Mycobacter ium avium subsp. Paratuberculos is is

a wel l establ ished etiolog ical agent o f JD(also

know n as par tubercu los is)


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Importance

Paratuberculosis is a chronic mycobacterial disease characterized by :

1. i r revers ib le wast ing

2. diarrhea and3. death from cachexia (wast ing sy ndrome) in rum inants.

caused by the obligate pathogen Mycobacterium avium subsp.Paratuberculosis (MAP).

Subclinical carriers are estimated to produce 15-16% less milk

no effective treatment.

M. avium subsp.paratuberculosis has also been implicated as a possible

cause of Crohns disease in humans

Control programs for paratuberculosis have been established in somenations including Australia, Norway, Iceland, Japan, the Neth-erlands andthe United States. (not in india)


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Etiology

Paratuberculosis results from infection byMycobacterium avium subsp.paratuberculosis

acid-fast rod previously known asMycobacteriumparatuberculosis andM. johnei

Some strains ofM. avium subsp.paratuberculosispreferentially infect specific hosts

The two main types (distinguished by restriction

fragment length polymorphisms RFLP)1. are the Type II or C strains, found in cattle

2. type I or S strains, found in sheep


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Species Affected

Paratuberculosis affects domesticated and

wild ruminants including cattle, sheep, goats,llamas, alpaca, camels, moose, elk, bighorn

sheep, buffalo, deer and reindeer.

Disease has been reported in wild rabbits,

nonhuman primates and pigs also.


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Geographic Distribution

Paratuberculosis can be found worldwide

Only Sweden and some states in Australiaare proven to be free of this disease


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Transmission

In ruminants

1. transmitted by the fecaloral route.

2. from colostrum, milk, udder, and the male andfemale reproductive tracts

3. Transmission can occur on fomites, and insectsmay act as mechanical vectors

Young animals are most susceptible to infection1. Get infected when they drink milk or colostrum.

In utero infections may also be seen.


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M. avium subsp.paratuberculosis is resistant

to environmental conditions and can survive

on pastures for more than a year

Viable bacteria have also been found for up

to a week in bovine urine, and for up to 8-11months in bovine feces.

In one study, this organism survived for as

long as nine months in pond, tap or distilled

water;


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Clinical Signs

Three stages of Johnes disease in cattle:

STAGE 1- Infected but showing no clinical signs and

not shedding MAP. Typically this stage occurs in

calves, heifers and young stock less than two years

of age and many adult animals exposed to small

doses of the disease-causing organism. This stage

progresses slowly over many months or years to

Stage II.


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Stage 2- Infected, shedding MAPbut

showing no clinical signs. Typically this stageoccurs in older heifers or adults. These

animals pose a major, but often hidden,

threat for infection of other animals through

contamination of the environment.


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Stage 3- Shedding MAPand showing clinical signs.

The onset of Stage III is often associated with a

period of stress, such as recent calving.

Cattle at this stage have-

1. intermittent, watery manure.

2. Animals lose weight and gradually drop in milk production but

continue to have a good appetite.

3. Most of these animals are shedding billions of organisms

4. In the final and terminal aspects of Stage III of the fatal disease,

animals become emaciated with fluid diarrhea and developbottle jaw.


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Diarrhea: an early sign of Johne's disease

in cattle


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Signs of Johne's

disease include

diarrhea andrapid weight loss.

Typically,

affected animals

remain brightand alert, without

fever, and eating

well.


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"Bottle jaw", also calledsubmandibular edema,

is a sign very typical ofJohne's disease. Thecause of bottle jaw is alack of protein in theserum, particularly

albumin, due to thedecreased function ofthe intestine. Johne'sdisease is a protein-losing enteropathy.


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The last portion of the smallintestine, or ileum, shown inthe upper part of the photois thickened due to theinflammatory responsecaused by an M.

paratuberculosis infection.Normally the intestine is thin

and pliable as seen in thelower half of the photo.Such intestinal thickening isless pronounced in speciesother than cattle


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In sheep and goats, the wool is oftendamaged and easily shed, anddiarrhea is less common than in cattle.

Clinical signs in other animals


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Post Mortem Lesions

In cattle

the carcass may be thin or emaciated

characteristic lesion is a thickened, often corrugated, wall in the distal

small intestine. more advanced cases, the lesions can extend from the duodenum to

the rectum.

mucosa is not ulcerated

mesenteric lymph nodes and other regional nodes are often enlargedand edematous.

Histologicaly , the lesions are characterized by diffuse granulomatousenteritis, with the accumulation of epithelioid macrophages and giantcells in the intestinal mucosa and submucosa

Acid-fast organisms may be found inside macrophages.


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Enlarged mesenteric

lymph nodes atnecropsy


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In other animals

Similar lesions occur in sheep and goats The mucosa is often only slightly thickened in

these species, but caseated or calcifiednodules are sometimes found in the

intestines and associated lymph nodes. In camelids--lymph node necrosis and

mineralization can also occur.


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Treatment

no satisfactory treatment

some combinations of antibiotics might besuccessful

long-term treatment would probably be

required and it is not likely to be

economically feasible

the chance of a complete cure is low


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Diagnosis

Labo ratory tests

variety of tests can be used . the choice of test varies with the stageof disease.

subclinical carriers can be identified with serology

delayedtype hypersensitivity (DTH) reactions,

polymerase chain reaction (PCR) assays or

fecal culture

Clinical cases can be diagnosed by culturing M. avium subsp.paratuberculosis from the feces or tissues

by demonstrating the organism with microscopy

DNA probes or PCR


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Microscopy

ZiehlNeelsen stains can be used to detect M. avium

subsp.paratuberculosis in the feces

clumps of small, strongly acid-fast bacilli are

diagnostic

Organisms may also be found in smears from the

intestinal mucosa or the cut surfaces of lymph nodes


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high power magnificationphotomicrograph of a Ziehl-

Neelsen acid-fast stained

histopathology section of

the bovine ileum

mycobacteria (red rod-

shaped bacteria) can be

seen


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Giant cells result fromfusion of several

macrophages. Suchcells are a hallmark ofgranulomatousinflammation and typicalof the host response toM. paratuberculosisinfection. The specifictype giant cells mostoften seen in Johne'sdisease are calledLanghans giant cells.


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The standard method fordiagnosis of Johne's disease is

isolation ofM. paratuberculosison standard bacteriologicalmedia. Shown here is one typeof such media, Herrold's eggyolk agar. Growth of slow-growing, small, white-yellow

colonies only on mediacontaining mycobactin (two lefttubes) is indicative ofM.

paratuberculosis. This test isusually done on fecal samplesand typically takes 12 to 16

weeks.
http://www.johnes.org/glossary.htmlhttp://www.johnes.org/glossary.html


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Colonies ofM.paratuberculosis grown on

Middlebrook agar mediawithout Tween are rough inappearance. Tween 80 is asurfactant commonly used inculture media to accelerate thegrowth of mycobacteria. ForM.

paratuberculosis, Tween 80can alter the colonial andcellular morphology.


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Serology and tests

Humoral immu nity usu al ly develops 10 to 17 mo nths af ter infect ion

Serology can be used

1. for the presum pt ive ident i f icat ion of infected animals2. to est imate the prevalence of infect ion in a herd

3. conf irm p aratuberculosis in animals with cl in ic al signs

(Animals that have cleared the infect ion can be seropos it ive)

var iety of serologic al tests are

1. com plement f ixat ion

2. enzyme-l inked imm unos orbent assays (ELISAs)

3. agar gel immun odif fu-sion

4. Intradermal test in g

test ing with jo hnin or avian puri f ied prote in derivat ive tubercul in can detect delayed-typehypersensit iv- i ty (DTH) react ions to M. avium subs p. paratuberculosis ; how ever, th is testis insensit ive and nonspecif ic react ions are common DTH react ions m ay diminis h ordisappear as th e disease progresses.

Exposur e to other myc obacter ia, includin g environm ental saprophy tes, can result in fa lseposit ives


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A simple two-day test to confirm adiagnosis of Johne's disease incattle is the AGID serum from the

animal is place in one well, apositive control is place inanother, and soluble antigen isplace in the third (top well).Formation of a white line ofprecipitation between the sample

well and the antigen well (arrow)is considered a positive test.

This test is commercially knownas Rapid Johne's Test .


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The present ELISA uses PPA antigen from

the Map Bison type bacilli infecting domestic

livestock population of Northern India.


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Samples to col lect

Although the link is speculative, veterinarianscollecting samples should keep in mind that this

organism may be linked to Crohns disease(achronic enteritis of humans)

M. avium subsp.paratuberculosis can be isolatedfrom the feces, mesenteric, ileal and ileocecal lymphnodes, and thickened areas of the intestinal wall

Serum samples may be taken for serology.

Fresh, frozen or preserved milk samples can betested with the milk ELISA.


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The Iceberg Phenomenon infection in

the herd

In the typical herd, for every animal showing

clinical signs (Stage III), many other cattle

are present in the earlier stages of the

disease. For every obvious clinical case

(Stage III) of Johnes disease on the farm,

15-25 other animals are likely infected. Theclinical case represents only the tip of the

iceberg of the Johnes infection.


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For every stage III cow expect-

1-2 more cows in Stage III (clinicallydiseased)

6-8 cows in Stage II (unapparent carrier

adults)

10-15 cows in Stage I (infected calves &

young stock)


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Although test and removal procedures can reduce

the prevalence of infection, good management

practices are needed to reduce transmission withinthe herd

There is no satisfactory treatment for the disease

the trend toward intensive livestock production

practices has made control more difficult

Disease control is via implementing a variety of

production practices described below

Present scenario


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Management Recommendations for

Farm

A. Calving area-

Consider individual calving pens. Properly managed calving

pens are ideal. Keep clean and put one cow in at a time. Focus on keeping other adult manure away from the calves.

If individual calving pens are not available, be sure to keepthe calving area as clean and dry as possible.

Do not use calving pens for sick cows, Johnes diseasepositive cows or cows sick with Johnes disease.

Remove calves from cows and cow area as soon after birthas possible. The sooner the better.


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B. Pre-weaned heifer calves-

Do not feed pooled colostrum or milk.Consider pasteurization if you must feedwhole milk.

Limit or avoid any contact with adult cows orcow manure.

Wear clean overalls & boots and use cleanequipment when working with or feedingcalves.


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C. Post-weaned heifers-

Minimize any contact with adult cows or cowmanure (including any manure run off that

may go into heifer pens).

Avoid & minimize cow manure on buckets,

skid loaders, tractors, tires and otherequipment.


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Bred heifers-

Keep bred heifers separate from cows for aslong as possible.

Avoid feeding heifers refused (weigh back)

feed from cows.


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E. Cows & bulls-

Avoid spreading manure on hay ground orpastures, especially in the same season.

Identify and manage any test-positive cows

until they can be sold. Dont feed their

colostrum to heifer calves.


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F. Replacements & Additions-

Be sure to purchase replacements fromherds where the Johnes status is known.

Be aware of management practices and

manure exposure when using a heifer raiser.


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Hidden costs associated with Johnes

disease include...

Premature culling of clinical or infected animals.

Increased veterinary costs.

Increased replacement costs.

Increased susceptibility to other disease and possible breedingproblems.

Increase in overall cull rate.

Decreased milk production in infected but normal-looking animals.(Production effect depends on parity, stage of disease and stageof lactation.)

Decreased slaughter value of 20% to 30%. Decreased pool of available replacements, thereby limiting genetic

pool.

Decreased feed efficiency.

Loss of marketing animals for sale.

Loss of investment in young stock that have been infected or exposedsince birth.


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Job of a veterinarian

Because Johnes disease is a hidden disease, testing should be a partof a management plan. Testing for Johnes disease can help you:

1. Determine if an animal exhibiting defi nite clinical signs is Johnes

disease positive and should be culled.2. Identify infected animals with suspicious clinical signs early before

they further contaminate facilities and lose salvage value.

3. Evaluate the extent of infection in your herd.

4. Monitor progress of control efforts.

5. Know if you are marketing infected or low-risk cattle and, as a result,know if you are contributing to the spread of the disease to producersherds or helping producers prevent Johnes disease from entering theirherd.

6. Know if you are about to purchase a Johnes disease test-positive orlow-risk animal before its brought into the herd.

Following table contents can be


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Following table contents can befollowed by the veterinarian to controlJD in a herd


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my presentation on johnes disease

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