Lecture 10 (Nervous System I)

What is Listeriosis known as?

Circling Disease

The most common clinical manifestation of listeriosis is a localized ascending asymmetric infection of the brain stem of ruminants by what bacteria?

Listeria monocytogenes

The resultant meningoencephalitis associated with Listeria monocytogenes damages the origins of what cranial nerves?

CN V, VII and VIII in the brain stem

• V = Trigeminal

• VII = Facial

• VIII = Vestibulocochlear

What does the meningoencephalitis damaging the origins of cranial nerves V, VII and VIII in the brainstem result in?

• Unilateral facial paresis or paralysis

• Head tilt

• Loss of sensation

• Depression

• Recumbency

What is diagnosis of listeriosis in ruminants based on?

Typical neurologic clinical signs

What treatment for listeriosis in ruminants may be effective if given early in the course of infection?

High dosages of antimicrobials

What bacteria are the following characteristics of?

• Small, gram-positive, non-spore forming rod

• Grows on non-enriched media

Listeria

Can Listeria tolerate both wide temperature ranges and pH ranges?

Yes - (4*C to 45*C) and (ph 5.5 to 9.6)

What should you expect to see with Listeria on blood agar?

Small hemolytic colonies

Listeria is ______ anaerobic, catalase-_________ and oxidase-__________.

• Facultative

• positive

• negative

What is at 25*C for Listeria?

Tumbling motility

Listeria hydrolyses what?

Esculin

Listeria are considered environmental what?

Saprophythes

What are outbreaks of listeriosis often related to?

Silage feeding

Which Listeria spp. is more pathogenic, associated with CNS infection and causes disease in both animals and humans?

Listeria monocytogenes

Which Listeria spp. is less pathogenic, not associated with CNS infection and causes abortion in cattle?

Listeria ivanovii

What are the hosts for Listeria monocytogenes?

Sheep, Cattle, Goats, Dogs, Cats, Horses, Pigs, Birds, Humans

What disease can be caused by Listeria monocytogenes in sheep and goats?

Encephalitis (neural form), abortion, septicemia, endophthalmitis (ocular form)

What disease can be caused by Listeria monocytogenes in cattle?

Encephalitis (neural form), abortion, septicemia, endophthalmitis (ocular form), Mastitis (rare)

What disease can be caused by Listeria monocytogenes in dogs, cats and horses?

Abortion, Encephalitis (rare)

What disease can be caused by Listeria monocytogenes in pigs?

Encephalitis, Abortion, Septicemia

What disease can be caused by Listeria monocytogenes in birds?

Septicemia

What disease can be caused by Listeria monocytogenes in humans?

Foodborne enteritis, Abortion

What are the hosts for L. ivanovii?

Sheep and Cattle

What disease can be caused by L. ivanovii in sheep and cattle?

Abortion

What are the hosts for L. innocua?

Sheep

What disease is caused by L. innocua in sheep?

Meningoencephalitis (rare)

What are the 3 major syndromes associated with Listeriosis in ruminants?

1. Neural form

2. Visceral form

3. Abortions

What is the neural form of Listeriosis in ruminants?

Meningoencephalitis

What is meningoencephalitis in ruminants sometimes called?

“Circling disease” or “Silage disease”

What is the Visceral form of Listeriosis in ruminants?

Septicemia

Who is the Visceral form of Listeriosis seen in?

Neonates - especially calves, lambs, foals, piglets

T or F: Listeriosis can cause sporadic abortions in ruminants.

True

What is the incubation period of neural listeriosis?

Ranges from 14 to 40 days

What are the clinical signs associated with Listeriosis in ruminants?

Depression, drooping ears, animal holds the head to one side, protrusion of the tongue, salivation, paralysis of the face

In the neural form of Listeriosis, lesions in the bran stem (often unilateral) are composed of what?

Microabscesses and Perivascular lymphocytic cuffing

In sheep and goats with Listeriosis, what may follow within a few days of the emergence of clinical signs?

Recumbency and death

What may occur up to 12 days after infection with Listeriosis?

Abortion without evidence of systemic illness

With a short incubation period of 2-3 days, what is most commonly encountered in lambs although it may occur occasionally in pregnant sheep?

Septicemic Listeriosis

What lesions are associated with septicemic listeriosis?

Micro-abscesses on the heart, liver and kidneys

What may be seen in cattle and sheep with listeriosis?

Keratoconjunctivitis and iritis (ocular listeriosis)

How do Listeriosis infections occur? What may they result in?

By ingestion of contaminated feed and may result in septicemia, encephalitis or abortion

What do organisms associated with Listeriosis probably penetrate?

The M cells in Peyer’s patches in the intestine

How does Listeriosis spread occur?

Via lymph and blood to various tissues

In pregnant animals, listeriosis infection results in what?

Transplacental transmission

In ruminants with Listeriosis, development of CNS infections may occur as a result of bacteremia but also as a result of oral mucosal invasion possibly through the dental pulp followed by infection of what nerve with axonal transport to the brain especially the midbrain, pons and medulla oblongata?

Trigeminal Nerve

Listeriosis is seen worldwide, more frequently in what climates?

Temperate and colder climates

What is there a high incidence of with Listeriosis?

Intestinal carriers

The natural reservoirs of L. monocytogenes appear to be what?

Soil and mammalian GI tracts - both of which contaminate vegetation

Grazing animals ingest the organism and further contaminate vegetation and soil, how does animal-to-animal transmission of Listeriosis occur?

Via the fecal-oral route

Listeriosis is primarily a winter-spring disease of what?

Feedlot or Housed Ruminants

What enhances multiplication of L. monocytogenes?

The less acidic pH of spoiled silage

When do Listeriosis outbreaks typically occur?

>10 days after feeding poor-quality silage

What often stops the spread of listeriosis, however, feeding the same silage months later may result in new cases?

Removal or change of silage in feed rations

What type of parasite is Listeria?

Facultative intracellular parasite

Listeria invades epithelial cells and/or phagocytic cells and escapes from the phagosome via the production of what that breaks down the phagosome membrane?

Listeriolysin (hemolysin)

What happens once Listeria is in the cytoplasm?

It begins replication

How can Listeria spread intracellularly?

Via the formation of actin tails (using host cell actin) that propel the bacterium forward & eventually through the cell membranes into a new host cell

What might be suggested by characteristic neurological signs or abortion in association with silage feeding?

Listeriosis

Appropriate specimens for lab examination depend on the form of the disease - what should be taken from animals with neurological signs?

CSF and tissue from medulla and pons

Appropriate specimens for lab examination depend on the form of the disease - what should specimens from cases of abortion include?

Cotyledons, fetal abomasal contents and uterine discharges

Appropriate specimens for lab examination depend on the form of the disease - what are suitable samples from septicemic cases?

Fresh liver or spleen and blood

What does histological exam of brain tissue reveal when dealing with Listeriosis?

Microabscesses and heavy perivascular mononuclear cuffing in the medulla and elsewhere in the brain stem

What is the following identification criteria for?

• Colonies are small, smooth and flat with a blue-green color when illuminated obliquely

• Individual colonies are usually surrounded by a narrow zone of complete hemolysis

• Catalase test is positive

• CAMP test is positive w/ Staphylococcus aureus but not w/ Rhodococcus equi

• Esculin is hydrolysed

• Tumbling motility at 25*C

L. monocytogenes

What is L. monocytogenes susceptible to? Which is the drug of choice?

Penicillin (drug of choice), Ceftiofur, Erythromycin, Trimethoprim/Sulfonamide

Why are high doses required when treating Listeriosis?

Because of the difficulty in achieving minimum bactericidal concentrations in the brain

What is recovery from Listeriosis dependent on?

Early, aggressive antibiotic treatment

What if signs of encephalitis associated with Listeriosis are severe?

Death usually occurs despite treatment

T or F: In a Listeriosis outbreak, affected animals should be segregated.

True

Corn ensiled before being too mature and grass silage containing additives are likely to have a more acidic pH which does what?

Discourages multiplication of L. monocytogenes

Is listeriosis considered a zoonotic disease?

Yes

Are all human cases of listeriosis due to an animal source?

No

What have food borne outbreaks of listeriosis in people been associated with?

Raw milk or milk products (cheese), improperly pasteurized milk or milk products and contaminated raw vegetables including coleslaw

What has been observed as a result of handling aborted fetuses and placentae?

Cutaneous listeriosis