Bovine immunodeficiency virus: clinical disease

• 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.

Presenting signs

• Little has been established about natural BIV infection of cattle.
• Possibly non-pathogenic.
• Not oncogenic.
• Presumptive clinical signs are based on documented experimental disease and similarities to other lentiviruses e.g. HIV (human immunodeficiency virus) and FIV (feline immunodeficiency virus).

Acute presentation

• Persistently raised white blood cell count.
• Lymphadenopathy.
• Animals may be clinically normal and not decline for some time, if ever.
• Possible weight loss and emaciation.

Geographic incidence

• Serological and genomic evidence of BIV worldwide, including SW USA, Canada, Germany, Japan, Italy, Australia, Korea, Pakistan, Brazil and Zambia.
• BIV virus isolation recorded in only 4 cases (South America and Louisiana, USA).
• Seropositive cattle have been detected in the UK.

Age predisposition

• Animals can be infected experimentally at any age.
• Age predisposition of natural infection is undetermined.
• Slow, progressive disease so clinical signs, if they occur, are more commonly expected in older animals.

Public health considerations

• No evidence that BIV causes human (or any other mammalian) disease.
• BIV is used as a safe model for understanding the genomics of other lentiviruses especially HIV.

Cost considerations

• Individual cows - culling costs.
• Herd costs - positive contact cows should be removed from the herd.

Special risks

• Contact with infected body fluids of a BIV positive animal e.g. blood, semen, colostrum.
• A serologically positive animal is a risk to the rest of the herd.
• An infected bull has the potential to infect many cows at insemination before being detected.
• Shared needles during routine procedures of cattle e.g. vaccination.
• Communal sharing of colostrum Colostrum: overview.
• Biting flies may also play a role in transmission.