HUMAN
PAPILLOMA VIRUS (HPV) AND ANOGENITAL WARTS
HPV DNA typing has
demonstrated over 90 genotypes, of which HPV-6, HPV-11, HPV-16 and HPV-18 most
commonly infect the genital tract through sexual transmission. It is important
to differentiate between the benign genotypes (HPV-6 and 11) that cause
anogenital warts, and genotypes such as 16 and 18 that are associated with
dysplastic conditions and cancers of the genital tract but are not a cause of
benign warts. All genotypes usually result initially in subclinical infection
of the genital tract rather than clinically obvious lesions affecting penis,
vulva, vagina, cervix, perineum or anus.
Anogenital warts are
the result of HPV-driven hyperplasia and usually develop after an incubation
period of between 3 months and 2 years. They may be single or multiple,
exophytic, papular or flat. Perianal warts (p. 404), whilst being more commonly
found in MSM, are also found in heterosexual men and in women. Rarely, a giant
condyloma (Buschke-Lewenstein tumour) develops with local tissue destruction.
Atypical warts should be biopsied. In pregnancy warts may dramatically increase
in size and number, making treatment difficult. Rarely, they are large enough
to obstruct labour and in this case delivery by CS will be required. Perinatal
transmission of HPV rarely leads to anogenital warts, or possibly laryngeal
papillomas, in the neonate.
A
variety of treatments are available including the following:
ü Podophyllotoxin,
0.5% solution or 0.15% cream (contraindicated in pregnancy) applied 12-hourly
for 3 days, followed by 4 days' rest, for up to 4 weeks is suitable for home
treatment of external warts.
ü Imiquimod
cream (contraindicated in pregnancy) applied 3 times weekly (and washed off
after 6-10 hours) for up to 16 weeks is also suitable for home treatment of
external warts.
ü Cryotherapy
using liquid nitrogen to freeze warty tissue is suitable for external and
internal warts but often requires repeated clinic visits.
ü Hyfrecation-electrofulguration
that causes superficial charring-is suitable for external and internal warts.
Hyfrecation results in smoke plume which contains HPV DNA and the potential to
cause respiratory infection in the operator/patient. Masks should be worn
during the procedure and adequate extraction of fumes should be provided.
ü Surgical
removal.
The use of condoms to prevent the transmission
of HPV to non-infected partners should be encouraged. However, HPV may affect
parts of the genital area not protected by condoms. HPV vaccines are under
development.
