equine infectious anaemia=lecture

EIA

MP Gupta

EIA

Swamp fever, Equine Malaria

• Equine infectious anemia is viral

disease limited to horse donkeys and

mules and is characterized by

recurrent episodes of fever hemolytic

anemia, icterus depression edema and

chronic weight loss.

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• This disease is more likely occurs in the

low-lying areas where water and

marshy condition are conducive to

insect multiplication.

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Etiology

• It is caused by Lentivirus of the family

Retroviridae.

• Virus can survive boiling for 15

minutes and is killed by sunlight.

• Virus persists for several months in

dried blood and excretions.

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Etiology

• A feature of lentiviruses is their ability

to hijack macrophages.

• ( Reoviridae is NE whereas REtroviridae

is E- Maedi visna, commonly called

ovine progressive pneumonia, Avian

Leukosis, HIV, EIA, Simian

Immunodeficiency virus belong to

Retroviridae)

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Morbidity/mortality

• Morbidity: 100%

• Mortality: 59-70%

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IP

• 2-4 weeks

• 14 days to several months

• a week to 45 days or longer(OIE)

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Epidemiology

• All breeds and age groups of Equidae

are susceptible.

• Use of unsterilized syringes in the

treatment or control of other disease

can transmit the disease.

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Geographic Distribution

•

• Equine infectious anemia has been

found nearly worldwide. This disease

appears to be absent from a few

countries including Iceland and Japan.

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• Biting flies particularly Tabanidae

(Tabanus) Stable flies (Stomoxys

calcitrans) and mosquitoes can

transmit the infection.

• Intrauterine infection may occur but it

is uncommon.

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• Virus is present in all tissue secretions

and excretions and may present in the

body for upto 18 years preventing re-

infection but providing a source of

infection for most of the animal’s life.

These clinically normal carriers are

usual means by which the disease is

introduced into clean areas.

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Pathogenesis

After entry the virus is present in the blood and all tissues and discharges (liver, kidney, spleen and lymph nodes)

Viral titres in the blood are particularly high during febrile episodes and it is at these times that the potential for transmission to unaffected horses is highest.

Virus persists in the WBC of all infected horses and is quite stable in serum. The intima of the small blood vessels and erythrocytes are damaged.

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Damage to the intima of the blood vessels and reticuloendothelial involvement is followed by inflammatory changes in the parenchymatousorgans particularly the liver.

Changes occur in the nervous tissue and result in the ataxia and encephalomyelitis.

The hemolysis, which is both intravascular and extravascular, is characterized by shorter lifespan of erythrocytes

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Virus can pass the placental barrier and infect the fetal foal.

It is generally assumed that the anemia and glomerulonephritisresults from the deposition of complexes composed of viral antigen and antibody.

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Clinical Signs

• Initial depression, weakness and

anemia and in-cordination.

• Intermittent fever,105oF which may

vary 1oF with in 1 hour.

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• Jaundice, edema of the ventral

abdomen, the prepuce and legs and

petechial hemorrhage in the mucosa

under the tongue (alos in AHS) and in

the conjunctiva.

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• Increased heart rate with audible heart

sound

• Abortion in the mare is common.

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• In chronic stages, the appetite is

usually good although alllotrophagia

may be observed. Some affected

animal appears to make a complete

recovery although they may remain

infected and suffer relapse in later

years.

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• Alimentary involvement is not

commonly recorded in the EIA but a

fetid watery diarrhea has been

observed.

• Death occurs after a course of 10 – 14

days of illness.

• Morbidity rate is 100% and mortality

rate is 70 % in some herds.

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Dx• 1.By hematological examination

• Marked reduction of RBC

• PCV decreased (14 to 20%)

• Increased monocytosis

• Increased ESR about 50% in 15 minute

• Slight Leukopenia (down to 2000/ml) with a

marked neutropenia and a lymphopenia

• Total serum protein is reduced and albumin:

globulin ratio is below normal.

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• 2. By serological tests

• Immunodiffusion test

• cELISA

• 3. Reverse-transcriptase polymerase

chain reaction (RT-PCR)

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Samples to collect

• Serum should be collected for

serology. Blood samples are taken for

RT-PCR, virus isolation or inoculation

into a test animal.

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• 3.PM findings

• S/c edema, jaundice and petechial and

ecchymotic hemorrhage

• Enlargement of liver, spleen and local lymph

nodes

• Intravascular clotting(DIC)

• Emaciation and pallor tissues

• Extensive proliferation of reticuloendothelial

system, perivascular round cell infiltration,

especially in the liver, hemosiderosis and a

glomerulitis.mohangupta63@gmail.com

• Horse, heart. Pale

cardiac muscle,

focal white areas of

myocardial

degeneration, and

reddened

hemorrhagic areas

(possible hypoxia

during death).

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Differential Dx

• a) Leptospirosis

• Milder and spontaneous recovery

• Hemoglobinuria is present

• Caused by Leptospira sp.

• b) Babesiosis

• Caused by Babesia sp.

• Hemoglobinuria? and hemoglobinemia

is present

• Transmitted by ticksmohangupta63@gmail.com

• c) Ehrlichiosis

• Limb edema and ataxia in the infected

horses

• Leukopenia, thrombocytopenia and

hyperbilinemia.

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• equine viral arteritis,

• purpura hemorrhagica,

• severe strongyliasis or fascioliasis,

• phenothiazine toxicity,

• autoimmune hemolytic anemia

• and other diseases that cause fever,

edema and/or anemia.

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Rx

• No specific treatment is available.

• Blood transfusion & Hematinic drugs

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Control

• Quarantine management: 6 month

quarantine

• Destruction of all infected animals

after confirmation of the infection

(Test and slaughter policy)

• Drainage of marshy land and insect

control use of sterilized syringe and

needles

• No satisfactory vaccine has been

developed mohangupta63@gmail.com

Disease Prevention

• Equine Infectious

Anemia

– Coggins Test

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• A vaccine is available, called "Chinese

Live Attenuated EIA vaccine",

developed in China and widely used

there since 1983. Another attenuated

live virus vaccine is in development in

the United States

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• Reuse of syringes and needles is a risk factor

for transfer of the disease.

• Options for the horse include sending the

horse to a recognized research facility,

branding the horse and quarantining it at

least 200 yards from other horses for the

rest of its life, and euthanizing the horse.

• EIA-positive horses are infected for life.

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Public Health

• There is no evidence that equine

infectious anemia is a threat to

humans.

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