402 G.A. Cabral and A. Staab
4
Effects of Marijuana and Cannabinoids on Human Health
4.1
Effects Related to Infections
Other Than with the Human Immunodeficiency Virus
To date, there is no direct evidence that marijuana smoking or therapeutic ad-
ministration of cannabinoids leads to an increased incidence of infectious disease
in humans. Cohen (1976) reported that based on a University of California at
Los Angeles (UCLA) 94-day cannabis study, exposure to marijuana did not alter
immune responses. Hollister (1986) reported that no clinical consequences were
noted from the effects of marijuana on the immune system. Sidney et al. (1997)
examined the relationship of marijuana use to mortality for a population of 65,171
Kaiser Permanente Medical Care Program enrollees, aged 15 through 49 years,
who completed questionnaires about smoking habits, including marijuana use,
between 1979 and 1985. Mortality follow-up was conducted through 1991. Mari-
juana use in a prepaid health care-based study cohort was found to have little effect
on non-AIDS mortality in men and on total mortality in women. Also, in a study to
evaluate the relationship between marijuana use and sexually transmitted diseases
in pregnant women, antenatal marijuana use was found to be unrelated to sexually
transmitted infections during pregnancy (Miller et al. 2000).
In contrast, there are reports that cannabinoids and marijuana exert deleterious
effects on immune function and host resistance. Juel-Jensen (1972) indicated anec-
dotally that individuals infected with HSV who were marijuana smokers had an
increased recurrence of genital viral lesions. Also, Harkess et al. (1989) reported on
six unrelated outbreaks of hepatitis A among users of marijuana and intravenously
administered methamphetamine. Although the exact mode of transmission could
not be determined, it was indicated that practices associated with illicit drug use
could have facilitated transmission of hepatitis A. Gross et al. (1991) reported that
marijuana use altered responsiveness of human papillomavirus to systemic recom-
binant IFN-α2a treatment and suggested that THC could be a cofactor influencing
theoutcomeofinfection.Liauetal.(2002)investigatedtheassociationbetweenbio-
logically confirmed marijuana use and laboratory-confirmed sexually transmitted
diseases and condom use among African-American female adolescents. Among
the 522 study subjects, 5.4% tested positive for marijuana. It was concluded that
the adolescents were more likely to test positive forNeisseria gonorrhoeae and
Chlamydia trachomatis, to have never used condoms in the previous 30 days and
to have not used condoms consistently in the previous 6 months, and that sexu-
ally transmitted disease and sexual risk behavior may co-occur with marijuana
use. Crosby et al. (2002) identified psychosocial predictors ofTrichomonas vagi-
nalis infection among low-income African American adolescent females living
in a high-risk urban area of the United States. The strongest multivariate pre-
dictor ofT.vaginalisinfection was biologically confirmed marijuana use. Kagen
et al. (1983) studied the possible role of marijuana in inducing sensitization to
Aspergillus organisms in 28 marijuana smokers. It was reported that the use of