Introduction

• Cause: bovine immunodeficiency virus (BIV).
• Signs: lymphadenopathy, persistent lymphocytosis.
• Diagnosis: ELISA, PCR, virus isolation.
• Treatment: primary disease is unlikely to be treated.
• Prognosis: good if asymptomatic, poor if clinical signs, however positive cattle should be culled because of the risk to others.

Pathogenesis

Etiology

• BIV is a bovine specific retrovirus.
• Similarities to other lentiviruses including human immunodeficiency virus (HIV), feline immunodeficiency virus (FeLV), caprine arthritis encephalitis virus (CAEV), equine infectious anemia (EIA) and Maedi Visna Virus (MVV).
• Related to Jembrana disease virus Rickettsia: jembrana disease, a virus causing acute disease of Bali cattle.

Predisposing factors

General

• Stress can activate the BIV virus causing seropositive animals to progress to clinical disease.
• As yet, no evidence for vertical transmission like some lentiviruses (HIV).

Specific

• Feline leukemia virus (FeLV) exacerbates signs of FIV in cats.
• Experimental animals have suggested a similar association between BIV and bovine lymphosarcoma/leukemia.

Pathophysiology

•  The pathophysiology of natural infection of cattle is not clear.
• Cattle infected with BIV consistently -> viremia -> lymphadenopathy and persistently high WBC count.
• EITHER a period of quiescence may follow with decreased WBC, immunosupression and secondary infections, emaciation and death
• OR animal continues to be clinically normal.

Timecourse

• BIV is a chronic disease.
• There can be a long incubation period between infection and appearance of clinical signs.
• Infected cattle are infected for life and do not eliminate the virus.

Epidemiology

• Spread occurs from an infected animal; herds with one seropositive animal are most likely to have several more seropositive animals in the herd.
• Contaminated needles/instruments, shared colostrum, biting flies may help spread infection via body fluids from one animal to another.
• Mating with an infected animal.

Diagnosis

Treatment

Prevention

Outcomes