Chapters authored
Preventive Strategies against Human Papillomaviruses
Human papillomavirus (HPV) infection is among the most common viral infections of the reproductive tract. Out of more than 100 different types of HPV identified so far, only a few (termed as “high-risk” subtypes) are associated with cervical cancer. On the other hand, “low-risk” subtypes are associated with genital warts and other benign changes in cervical and oral mucosa. Majority of the HPV infections usually clear up without any intervention within a few months. However, a fraction of HPV infections, such as those with types 16 and 18, can become persistent which may lead to the development of anogenital or cervical cancers. HPV subtypes 16 and 18 together are responsible for approximately 70% of all cervical cancer cases, the fourth major cause of cancer-related deaths in women. In the absence of any specific treatment options, preventive measures are considered as cornerstone of strategies aimed at curbing the burden of this disease. This chapter presents a comprehensive review of strategies that can be employed to prevent and eradicate HPV infection. Minimizing the exposure to HPV risk factors such as unprotected sex, multiple sex partners, early age sex, and not being circumcised, can reduce the chances of getting HPV infection to a significant level. Mass screening programs have also been effective in HPV eradication. Nevertheless, immunization against HPV has proven to be the most promising strategy in fight against HPV. Virus-like particles based on bivalent, quadrivalent, and nonavalent anti-HPV vaccines have been licensed and are available in market under the trade names of Cervarix®, Gardasil®, and Gardasil9®, respectively. Various clinical trials and population-based studies have demonstrated high levels of efficacy for all the three vaccines in preventing type-specific malignancies.
Part of the book: Human Papillomavirus
Microbicides for the Prevention of HPV, HIV-1, and HSV-2: Sexually Transmitted Viral Infections
Sexually transmitted diseases (STDs) can be transmitted through genital-genital, orogenital, or anogenital contacts and remain to be a public health concern worldwide. Approximately one million people around the world are believed to be newly infected with sexually transmitted infections (STIs) each day. Numerous causative agents including bacteria, viruses, protozoa, yeast, and fungi are responsible for STIs; however, viruses exhibit more serious risks, probabilities and outcomes of STDs than other organisms. The most lethal viral STIs are human immunodeficiency virus-1 (HIV), herpes simplex viruses 1 and 2 (HSV-1 and HSV-2), and human papillomavirus (HPV), which are responsible for major sexually transmitted viral infections including AIDS, herpes simplex, and genital warts, respectively. Despite the fact that several prevention strategies such as vaccination, abstinence from sex, limiting sex partners, the use of condoms and a range of therapeutic drugs have drastically reduced the risk of contracting STIs, these three infections continue to spread at an alarming rate. The high incidence and lack of effective vaccine, instigated scientists to look for alternate, cheap, and efficient strategies for controlling these deadly viruses. Microbicide are relatively new approach that may be helpful in preventing STIs transmission when applied inside the genitals before intercourse. Like other interventions, microbicides are used as prophylactic measures against STIs. Therefore, an excellent safety and efficacy profile analysis is mandatory before their approval for human use. Although no safe and efficacious microbicide is yet available, many candidates including nonoxynol-9, Savvy, cellulose sulfate, Carraguard, VivaGel, tenofovir gel, and PRO 2000 have shown promising in vitro activity and many more are under development. However, very few of them have moved to large-scale phase III trials. This chapter aims to provide a brief overview of various microbicides along with their mechanism of actions and recent updates on safety and effectiveness trials.
Part of the book: Fundamentals of Sexually Transmitted Infections