Human Papillomavirus Infections: Epidemiology, Clinical Aspects and Vaccines

Abstract

Genital Human papillomavirus infections are the commonest sexually transmitted infections worldwide. The prevalence however in cytologically normal women varies from 1.4% in Spain to over 25% in some countries South of the Sahara. Globally about 10% of women are infected with HPV. The average duration of HPV infection is 4-20 months and the majority of infected individuals will clear the infection without any clinical consequences. Persistent infection with high-risk or oncogenic types of HPV is strongly associated with the development of preinvasive and invasive lesions of the ano-genital tract, including cancer of the cervix, anus, penis, vulva and vagina. HPV 16 is the most oncogenic type and is associated with an absolute risk of high grade cervical cancer precursors of 40% after 5 years of persistent infection. HPV infection of the epithelium is very effective at evading the host immune surveillance system due to the absence of a viraemic phase, using non-lytic replication and low expression of viral proteins until late stages of epithelial differentiation. Infection of the cervix with high-risk types of HPV is a necessary although insufficient cause of cervical cancer. Important co-factors include long term use of oral contraceptives, use of tobacco, co-infection with herpes simples, Chlamydia and HIV. This article discusses both secondary and primary prevention of cervical cancer, with particular emphasis on developing countries, where 80% of cervical cancer cases are found.

High uptake of Gardasil vaccine among 9 - 12-year-old schoolgirls participating in an HPV vaccination demonstration project in KwaZulu-Natal Province

“…[2] Globally, the prevalence of genital warts is high, especially in people living with HIV. [3] Though there is little information on incidence, genital warts are common among sexually active people and usually first occur in adolescence. [3] Genital warts are highly infectious, with a transmission rate of 65% within sexual partnerships; despite treatment, they can recur in up to 75% of cases.…”

“…[3] Though there is little information on incidence, genital warts are common among sexually active people and usually first occur in adolescence. [3] Genital warts are highly infectious, with a transmission rate of 65% within sexual partnerships; despite treatment, they can recur in up to 75% of cases. [4] HPV types 6 and 11 are linked to genital warts, with 20 -50% of lesions also co-infected with high-risk HPV types.…”

“…Both vaccines have been shown to be safe, immunogenic and efficacious. [3,5,6] Although licensed for use in both the public and private healthcare sectors in SA, they are currently only available in the private sector. [1] The quadrivalent Gardasil vaccine (used in the HPV demonstration project) is indicated in females (aged 9 -26 years) for the prevention of cervical, vulvar, vaginal and anal cancers, as well as genital warts, and in males (aged 9 -26 years) for the prevention of anal cancers and genital warts.…”

“…[8] The World Health Organization has recommended that routine HPV vaccination be included in national immunisation programmes. 3 Goldie et al [8] have suggested that focusing existing resources on vaccinating girls, rather than dividing resources between girls and boys, is the most cost-effective way of reducing the lifetime risk of cancer in resource-constrained environments. In SA, the Extended Programme on Immunization (EPI), established in 1995, provides free vaccination of children against childhood diseases.…”

Seroepidemiology and High Negativity of IgG Antibodies Against Human Papillomavirus (HPV) Type 6, 11, 16, and 18 Virus-like Particles in Women of Childbearing Age in Port Harcourt, Nigeria

“…Human papilloma virus (HPV) is the most common sexually transmitted virus worldwide [1,2] and it is estimated that about 75% of sexually active women and men will acquire a genital HPV infection at some time. [2−4] Human papilloma viruses are pretty heterogenic and are classified in several types that include high-risk oncogenic types (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58.…”