can only survive in body fluids, and is transmitted by blood, semen,
vaginal fluid and milk. The disease can be contracted in the following
disease was first associated with homosexual communities, notably
in American cities such as San Francisco.
blood entering the blood stream
disease can be contracted through receiving blood or blood products
already infected with HIV. This was the case for some haemophiliacs
who were given factor VIII from infected blood. Extensive screening
programmes have been able to largely remove this threat in countries
with adequate medical facilities. It is also possible to contract
the disease through contaminated needles used for intravenous drug
mother to baby
infected pregnant woman can pass on the virus to her baby through
the placenta, at birth or through breast milk. The chances of the
infection being transmitted from the mother to her baby are estimated
to be 25-50%. This can largely be prevented by treating infected
pregnant women with the drug zidovudine
of the disease
but not necessarilly all, individuals infected with HIV progress
over time to AIDS. The following stages of the disease can be seen:
The initial infection with HIV may produce
a short flu-like illness, but often gives no symptoms.
The second stage is the period between infection and the onset of
clinical signs (HIV-positive phase). It generally lasts between
2 and 15 years. Although no symptoms are seen this period is not
static, there is persistent
replication of the virus and a gradual decline in function and numbers
of CD4 T cells.
The third phase sees the onset of opportunistic infections, which
at this point are not major. Common bacterial, viral and fungal
infections occur. Oral and genital herpes or athlete's foot are
common examples. The duration of this type of infection is lengthened
compared to that in a healthy person. Loss of weight may also be
seen. There is a significant drop in the number of CD4 T cells.
Onset of AIDS-Opportunistic infections (protozoal, viral, bacterial
or fungal), disease of body organs and development of secondary
cancers are common and life-threatening. Some individuals may lose
a great deal of weight.