MODES OF TRANSMISSION

MODES OF TRANSMISSION

Sexual contact. 95% of HPV infected patients acquired the disease through sexual contact (Fairley, 1993). HPV (all types) most frequently occurs in young women with multiple sex partners.

Vertical transmission from an infected mother to newborn. Less frequent mode of transmission. Difficult to detect due to the latency period between the infant’s exposure at birth and symptom presentation.

Horizontal transmission, or sexual transmission in children associated with sexual abuse. Recently identified mode of transmission. Rise in cases of HPV infected children parallels the rise in child abuse cases in the US (Fraiser, 1994).

Other pathways: Possibility of non-sexual transmission, e.g. contact with infected urogenital secretions from sharing towels or bathing together. No such cases have been clearly documented (Fraiser, 1994).

Recent research has shown that the risk of disease in the infant declines if the latency lasts more than a year (Fraiser, 1994).

RISK FACTORS FOR HPV

Sexual behavior is a primary risk factor for infection. Women with multiple sex partners have a higher risk of contracting HPV than monogamous women. One US study showed that HPV prevalence (as warts or cervical cancer) among women at an STD clinic was 4 to 13 fold higher than in the general population (Armstrong et al, 1986). Currently, there are no definitive studies on risk associated with different forms of sexual behavior.

Immune suppression is a risk factor for all people exposed to HPV. A person with a pre-existing immuno-compromised state and/or concurrent genital infection has a 17-fold increased risk of developing HPV-associated diseases. Several recent studies have confirmed the increased risk of HPV in people with HIV infection. It is plausible that an immunosuppressed status facilitates HPV infection and replication, increasing the likelihood of developing cervical neoplasm. However, exactly how HPV exploits a pre-existing immune-compromised state is under investigation.

*A study of 207 HIV-exposed women in New York showed that HPV prevalence was 23% among HIV seronegatives and 46% among HIV seropositives. The HIV+ women also had higher rates of oncogenic HPV types which progressed to cancer (as well as other HPV types). (Ho et al, 1994).

Age is also an associated risk factor. Young women, between the ages of 15 and 25 have a two fold higher risk of developing an HPV infection than women over 35 (AJMS).

Other possible risk factors have been associated with increased HPV infection in several studies, but their significance is not conclusive. They include: contraceptive use, pregnancy, smoking, and concurrent herpes infection. There is conflicting evidence whether using oral contraceptives reduces HPV risk in women.

Socioeconomic variables can affect HPV risk, detection, and treatment. Conditions of poverty, domestic violence, sexual abuse, inadequate health care, and lack of information about HPV that can facilitate HPV transmission and prevent early detection will increase one’s risk for developing an HPV infection. Unfortunately, it is these structural realities which are the most challenging to control.

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