Behavioral Research and STIs

1. Behavioral Research and STIs Objectives • Discuss how behavior influences the basic reproductive rate of an epidemic • Describe some of the behavioral models • Discuss the concept of Core Group • Discuss Social Network Analysis

2. Behavioral versus Clinical

3. Basic Reproductive Rate of Infection

4. The Reproductive Rate Ro > 1 epidemic Ro = 1 equilibrium Ro < 1 prevalence declines

5. Ro basic reproductive rate • Defines the average number of secondary infections generated by one primary case in a susceptible population of defined density • the host population is divided into compartments: susceptibles, infected (latent), and infectious

6. ()Transmission Probability • infected and susceptible • number of partners • types of partners • types of sexual acts • frequency of sexual acts • virulence of infection • duration of infection • when infection occurred • when infection was treated

8. Sexual Risk Behavior (Aral, 194) • Age at sexual debut • Number of sex partners • Non-discriminating sex partner recruitment • Sexual practices • Frequency of intercourse • Intercourse during menses • Condom use • Vaginal douching • Male circumcision

9. Behavioral Models of Disease

11. Trait Concept • Antisocial personality • Chronic self-destructiveness • Erotophobia-erotophilia • Impulsivity • Independence-conformity • Locus of control • Masculinity-femininity • Neuroticism-extraversion-psychoticism

12. Trait Concept • Risk taking • Self-efficacy • Self-esteem • Self-monitoring • Sensation seeking • Sex guilt • Social desirability

22. D - the Infectious Period

23. c - mean rate of sexual partner change • depends on demographic and social factors • magnitudes are correlated with other factors such as number of sex acts, type of sexual contacts and mixing. • Does a Core Group exist?

24. Core Group

25. Core Group(Thomas and Tucker, 1996) • Defined as: People who infected a large proportion of the time, infect more than one other person, are repeatedly infected, are prostitutes or their clients, geographic areas with large numbers of cases • Mathematical • Clinical-epidemiologic • sociocultural

26. Definitions applied to Core Group (Thomas and Tucker, 1996) • Groups whose prevalence of GC is > 20% • Prostitutes • Persons who have many sexual contacts • very sexually active persons who are asymptomatic when infectious • people repeated infected with STD • people with > 5 sex partners • people with clusters of high-risk behavior • adolescent males in detention • census tracts that are responsible for > 50% of cases

27. Social Network Analysis

28. Linear Concept of transmission of an STD

29. Network informed concept of disease transmission

31. Sexual Behaviors(Aral; 1994) • Early age at sexual debut • Large number of lifetime sexual partners • Large number of current sexual partners • Non-discriminating sex partner recruitment patterns • High risk characteristics of sexual partners • Specific sexual practices • frequency and timing of sexual intercourse • Sexual abuse during childhood

32. Health Behaviors(Aral; 1994) • Condom and Contraceptive use • Vaginal douching • Male circumcision • Health Care seeking • Compliance with therapy • Compliance with behavioral recommendations

33. Substance Abuse(Aral; 1994) • Associated with anonymous sex • Associated with exchange for drugs or money • Reduces likelihood that safer sex will be practiced • Includes injectables, inhalables, and alcohol

34. Transmission ProcessShiboski and Padian, JID 1996;174 Partner choice sexual contact population/ group level factors individual/ Partner level factors Transmission