Transfusion Transmitted Diseases

Hepatitis B

Hepatitis B virus (HBV) is transmitted through parenteral and sexual exposure. The incubation time is a mean of 90 days with a range of 30 to 180 days.

Donor blood is routinely tested for HBsAg and HBcAb. There is no routine testing for hepatitis A, because it is rarely transmitted by blood products.

Recipients of blood products can also be infected with hepatitis delta, which is a defective RNA virus that needs a HBV superinfection to replicate.

Persons who have received a hepatitis B vaccination (recommended for all health care workers with patient contact) will have hepatitis B surface antibody present, but not HBsAg or HBcAb

Risk of transmission (RT) = 1/66,000 to 1:200,000

Hepatitis C

The route of transmission is parenteral, with sexual transmission lower than previously throught. The mean incubation time is 6 to 8 weeks.

Blood Bank testing for HCV started in 1990. At present, only testing for hepatitis C antibody is available.

Risk of transmission (RT) = 1/121,000

Human Immunodeficiency Virus (HIV)

In 1982 the first cases of AIDS obtained from blood or blood components were reported, but the etiology of the infections was not known at that time.

By 1983 changes occurred in the donor cirteria to exclude those at high risk for transmission of HIV.

The first testing of blood products for HIV started in 1985 and is a test to detect the presence of antibody directed against HIV. Testing for HIV p24 antigen was mandated in 1996.

Risk of transmission = 1/563,000 to 1/825,000

Human T-lymphocytotrophic Virus (HTLV-1).

HTLV-1 is a retrovirus that is endemic in Japan and the Caribbean. Implicated as causing adult T-cell leukemia/lymphoma and a neurological disorder similar to multiple sclerosis.

Blood is routinely screened for antibodies to HTLV-1.

Risk of transmission = 1/641,000 (but only 1-3% of seropositive individuals will develop disease).

Cytomegalovirus (CMV)

The prevalence of CMV antibody ranges from 50 to 80% of the population. Blood contaminated with CMV can cause problems in neonates or immunocompromised patients.

Potential problems in selected patient populations can be prevented by transfusing CMV negative blood or frozen, deglycerolized RBC's.

Donor blood is not routinely tested for CMV.

Malaria

Malaria is rarely transmitted by RBC products, although the number of transfusion associated cases of malaria is at an all-time high.

There are no practical laboratory tests available to test donor blood, so donors travelling to high risk malaria areas are excluded from donating blood for six months.

Others

Additional diseases which are rarely transmitted by blood products, but for which no routine cost-effective laboratory testing is available include:

· Babesiosis.

· Lyme disease.

· Chagas' disease.

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