Control of STDs--the role of prophylactic vaccines against herpes simplex virus

Changing paradigms in dermatology: antivirals in dermatology

Almost all of the approved antiviral drugs have become available during the past two decades. Approximately one half of these agents are for the treatment of human immunodeficiency virus (HIV) infections and comprise five classes. The first three classes all act to inhibit reverse transcriptase: nucleoside analogs; nonnucleoside analogs; and nucleotide analogs. The fourth class, protease inhibitors, prevent viral packaging; the fifth class, fusion inhibitors, prevent fusion between HIV and the target cell. Four nucleoside analogs, acyclovir, valacyclovir, famciclovir and penciclovir, are approved for the therapy of herpes simplex and varicella zoster infections. Interferon alpha is approved in the injectable form for condyloma acuminatum and Kaposi's sarcoma, but the more efficient method of delivering this agent is via interferon induction following topical use of imiquimod cream. Antiviral agents are also approved for infections with cytomegalovirus, hepatitis B and C, respiratory syncytial virus, and influenza viruses. Most of these antiviral drugs are virastatic and not viracidal. Vaccines and public health measures are much more effective and cost effective than antiviral drugs and must be promoted accordingly in the defense against viral infections.

Age-specific prevalence of infection with herpes simplex virus types 2 and 1: a global review

Information on age- and sex-specific prevalence of herpes simplex virus (HSV) types 2 and 1 infections is essential to optimize genital herpes control strategies, which increase in importance because accumulating data indicate that HSV-2 infection may increase acquisition and transmission of human immunodeficiency virus. This review summarizes data from peer-reviewed publications of type-specific HSV seroepidemiologic surveys. HSV-2 prevalence is, in general, highest in Africa and the Americas, lower in western and southern Europe than in northern Europe and North America, and lowest in Asia. HSV-2 and -1 prevalence, overall and by age, varies markedly by country, region within country, and population subgroup. Age-specific HSV-2 prevalence is usually higher in women than men and in populations with higher risk sexual behavior. HSV-2 prevalence has increased in the United States but national data from other countries are unavailable. HSV-1 infection is acquired during childhood and adolescence and is markedly more widespread than HSV-2 infection. Further studies are needed in many geographic areas.

[What's new in vaccines against herpes simplex infections?]

Herpes simplex viruses (HSV) can cause a variety of infections, including genital herpes. Despite effective antiviral therapy HSV infections remain a public health problem. Vaccines offer the possibility for controlling the spread and limiting HSV disease, two strategies for herpes vaccination: prophylactic immunization or therapeutic immunization. The article discusses the results of different studies, in particular, concerning recombinant vaccines, DISC vaccines and DNA vaccines.

A model of the transmission and control of genital herpes

BACKGROUND

Mathematical modeling of herpes simplex virus type 2 transmission can provide insight into the behavior of the epidemic and the effects of control measures.

GOAL

To examine parameter sensitivity and assess control strategies.

STUDY DESIGN

The model simulates transmission in a young, sexually active, nonmonogamous population. The population is divided into compartments representing disease status (susceptible, exposed, primary infectious, asymptomatic, recurrent, vaccinated), and flows between compartments are described by differential equations.

RESULTS

With a base set of parameter values, the basic reproduction rate (R0) is 1.79, indicating that ultimate prevalence in this population will be 44%. The course of the epidemic is most sensitive to changes in behavioral parameters (time nonmonogamous and partner-change rate) and to the probability of transmission during the asymptomatic stage.

CONCLUSION

In the absence of behavior change, efforts to control the epidemic must focus on vaccine development and prevention of transmission during both symptomatic and asymptomatic phases.