World Veterinarian Prize Quiz - 2

 

Listeriosis

·         Listeriosis is a disease of ruminants particularly sheep.

·         The major diseases associated with Listeria monocytogenes are encephalitis and abortion.

·         In ruminants it is produces syndromes like septicaemia, uveitis, gastroenteritis, spinal myelitis and mastitis.

·         Sometimes observed septicemic condition in horses and pigs.

·         Higher incidence of disease in winter season.

 

Synonym :-

·         Circling disease

·         Meningo-encephalitis

·        Silage disease/ Silage sickness

 

Etiology:-

·         Listeria monocytogenes  has been isolated from 42 species of mammals

·         L. monocytogenes  22 species of birds,fish, crustaceans and insects.

·         Genus listeria consist 6 species

·         Listeria monocytogenes  & Listeria ivanovii  à Pathogenic

·          Listeria ivanovii  mild pathogenic but sometimes cause abortion in Cattle and Sheep.

·         Listeria innocua sometimes responsible for encephalitis in ruminant

·         Listeria monocytogenes  :-rode shaped , round ends, Gram positive , flagellated organism , motile organism

·         Growth: between 30°C and 37°C temp. and pH 4.5 and 9.6

·         Reproduction: between 1°C and 45°C temp.

·         Resistance temp:- −20°C (−6°F)

·          Listeria monocytogenes  5 serotype isolated from animal and 16 serovar

·         Organism isolate from faeces and silage

·         Organism seen different period:-

ü  Sheep faeces: 3 Months

ü  Damp soil: 11.5 Months

ü  Cattle faeces: 16.5 Months

ü  Dry straw: 207 days

ü  Dry soil & faeces : >2 years

 

 

  Hosts:-

·         It is distributed in worldwide.

·         all animals are affected but more commonly occurred in domestic animal { cattle,Buffalo,goat, sheep } and poultry

·         In dog it’s it extremely rare

·         Man will be also affect when they ingested infected animal milk.

·         Woody browse in goats which is may be a risk factor.

Transmission :-

·         It is infectious diseases so that transmitted by infected feed soil.

·         Mainly transmitted by silage and soil. Sometimes raw milk.

·         It also transmitted by rodents and carrier animal.

·         Most feed like hays, grains, and formulated feeds are contain L. monocytogenes but low level of water so don’t multiplication of bacteria.

·         Silage which contain pH less than 4.5 so bacteria can multiply at this stage.

      

Pathogenesis :-

Organism enter into bowel by infected feed material

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After entering in to bowel organism enter in circulatory system and produce bacteremia

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The organism localized in various organ and grow and they produce fatal septicemia

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  Some organisms enter into nasal mucous member and transmitted to brain via trigeminal nerve and develop the symptoms.

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Pons medulla ,meninges, ependyma are occupied by organism and produce the neurological lesions

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Some organisms goes into eye and produce catarrhal conjunctivitis.

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Organisms also affect the pregnant uterus. The infection occurred in early pregnancy than abortion occur and the infection occurred in late pregnancy than still birth occurred.

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Organism also present in udder so produce mastitis and organism spread through milk.

 

Clinical sign :-

·         Sheep :  

ü  Fever - 40°C (104°F) to 42°C (107°F)

ü  Incoordination

ü  Head deviation sometimes with head tilt

ü  Walking in circles

ü  Unilateral facial hypalgesia seen keratitis and corneal ulceration.

ü  Facial paralysis with dropping of ear

ü  Paralysis of lips and ptosis

ü  Panophthalmitis:- pus seen in the anterior chamber of one or both eyes

ü  Paresis of jaw muscles

ü  Death due to respiratory failure

·         Cattle: Same clinical sign like sheep but in more acute case death of animal within 2-4 days.

·         Goat: Same clinical sign like sheep but in young goat acute case death of animal within 2-3 days.

 

Mainly 3 forms of Listeriosis

1.     Encephalitis form

2.     Abortion form

3.     Septicemia form

 

·         Encephalitis/meningitis: Seen between the age of 6 and 12 weeks in lamb, in to sheep <6 week and ewes  =>2 years of age. The case–fatality is high in sheep due to short period.

·         Encephalitis:- dull, depression, dummy syndrome, head pressed on wall, circling movement, conjunctivitis, paralysis of pharynx.

·         Abortion:-

Cattle:- early pregnancy infection :- abortion

late pregnancy infection :- still birth   

Goat and Sheep: Abortion occur at 12 week of pregnancy.        

·         Septicemia:- it’s mainly affect the new born

The main sign is pyrexia, diarrhea, corneal opacity, dyspnea, nystagmus and death.

·         Spinal myelitis: Not more commonly seen but recorded in cattle B/W 12-18 month of age.

Zoonotic important :

·         In human cause by food borne infection like soft cheese, unpasteurized milk, fermented raw meat sausages, hot dogs, smoked fish, pate and deli meats.

·         Susceptible all age of human

·         Symptoms like meningioencephalitis, septicemia, abortion and neonatal infections.

·         High case fatality and 25 % case mortality reported.

·         Dermatitis with a papular and pustular rash seen on the arms of veterinarians when they handling of infected case of dystocia and aborted fetuses.

·         Conjunctivitis is reported in agricultural workers handling infected livestock.   

 Macroscopic Lesions :-

1.     Abortion form

ü  In fetuses necrotic foci in the liver & spleen .

ü   In placenta- necrosis of placental villi & become covered by purulent exudates

2.     Encephalitis form

ü  The meninges are thickened by greenish edema.

ü  Grayish foci of softening may be found in the cross section of medulla.

 

3.     Septicemia form

ü  Small focal necrotic lesion found in liver & all organs (milliary abscesses).

ü  In very young animals  gastroenteritis may be present

 

Microscopic Lesions :-

1)      Micro abscesses in brain.

2)      Vasculitis in white matter

3)      Perivascular cuffing.

4)      Meningitis.

5)      Area of malacia (softening) due to thrombosis

6)      liver, spleen, and myocardium showing necrotic foci

7)      microabscesses observe throughout the intestine and it is characterized by  infiltration of degenerating neutrophils in the mucosa lamina muscularis of the abomasum

 

Microscopic Images: (Courtesy Dr. M.D. McGavin, College of Veterinary Medicine, University of Tennessee.)

Diagnosis:

·         Base on clinical sign

·         Base on microscopic and macroscopic lesions

·         Bacteriological examination or culture or FAT(Fluorescent Antibody Test)

ü  Brain steam, liver, lung, spleen, placenta,abomasum, small intestine, messentric lymphnode

·         Anton’s test:

ü  Inoculation of live bacterial broth culture in to the conjunctiva of rabbit or guinea pig only L.monocytogenes cause purulent keratoconjuctivitis within 24-36 hrs of inoculation

·         Grow on nutrient agar, blood agar, but not on MacConkey agar

·         Small, transparent, smooth colonies

·         Blue green colony seen when light is reflect

·         L.monocytogenes Produce narrow zones of beta haemolysis while L.ivanovii produce relatively wide zone

·         Selective Medium:

ü  By addition of 0.05% potassium tellurite in tryptose agar. (Black jet colonies)

·         On BHI agar colony shoes a typical blue-green color when light is reflected obliquely at a 45⁰  angle of their surface

·         When grown in semisolid media the Listeria spp. Give an umbrella shaped growth in substance.

·         Selective ager/broth-Tryptose agar, PALCAM agar, CHROM Agar, Trypticase soya broth

 

Differential Diagnosis:

       v  Encephalitis

•        Pregnancy toxemia in sheep

•        Nervous ketosis in cattle

•        Rabies

•        Polioencephalomalacia

•        Middle ear disease

•        Scrapie

•        Gid

      v  Keratoconjunctivitis/Uveitis

 

·         Infectious bovine keratoconjunctivitis

·         Contagious ophthalmia

 

Treatment:-

1)      Chlortetracycline 10 mg/kg b.w for one week (IM)

2)      Penicillin 44000 IU/kg b.w. for one week (strictly IM)

3)      Ampicillin also give

4)      Sulphonamide 100 – 150 mg/kg b.w for 3 days

5)      Supportive therapy like electrolytes , fluid (NS / RL )

6)      Good nutrients and good diet required

Control:-

·         Go for vaccination 1^st  {killed or live}

·         Isolate the infected animals

·         Burning the bedding and litter material of infected animal

·         Proper treatment of infected animal

·         Ensilage should not be give to animal which made in enzootic area.

 

 

References:

Pathologic Basis of Veterinary Disease Expert Consult

6th edition

By: James Zachary, M. McGavin