Syphilis tetanus and Malaria

The main focus of research connecting IDU with infectious disease has been on the aforementioned viruses: HIV, HCV, and HBV However, multiple recent reports indicate that injection drug users are at increased risk of a whole host of other blood-borne infections, including: syphilis, tetanus, wound botulism, and malaria (Passaro et al., 1998; Chau et al., 2002; Beeching and Crowcroft, 2005; Bradshaw et al, 2005).

Incidence rates of syphilis infections, caused by the spirochete Treponema pallidum, have been steadily rising for the past two decades in at-risk populations in multiple areas throughout the world (Muga et al., 1997), though it is not yet clear whether the association is related to transmission via sharing of syringes, or because injection drug users exhibit higher-risk sexual behaviors of which syphilis infection is representative (Karapetyan et al., 2002). Studies evaluating syphilis prevalence among drug users have consistently shown that injectors practice higher-risk sexual behaviors (Lopez-Zetina et al., 2000). Furthermore, there are significant racial, gender, and socioeconomic disparities in syphilis prevalence. In the US, syphilis prevalence rates among African-Americans have been estimated to be 60 times higher than those in non-Hispanic Whites (Lopez-Zetina et al., 2000). In studies completed in both the former Soviet Union and the USA, there are much higher syphilis prevalence rates among women when compared with men, thought to be associated with high-risk commercial sex workers (CSW) (Muga et al., 1997; Karapetyan et al., 2002; Abdala et al., 2003). While syphilis is a treatable condition, by virtue of the high prevalence rates among injection drug users it shares many risk factors with HIV (Fleming and

Wasserheit, 1999). Furthermore, syphilis-caused open genital lesions greatly enhance transmission of HIV, resulting in the increased spread of this non-treatable virus both within the injection drug user population and beyond, due to complex sexual networks.

The association between tetanus and IDU was first recorded in 1876 in the UK, and was further elucidated in the 1950s in Chicago (Levinson et al, 1955; Beeching and Crowcroft, 2005). Tetanus is caused by infection with Closridium tetani, which belongs to the family of obligate anaerobes Clostridium. Infections by this family of bacteria are traditionally associated with ingestion or with highforce crush injuries, but when injection drug users employ contaminated needles to inject areas of devitalized tissue, they also are at high risk of self-inoculation (Passaro et al, 1998). Tetanus is the only member of this family for which there is a vaccine. Although its use does provide lifelong immunity, booster vaccines are generally recommended every 10 years. C. Tetani is not the only member of this family to cause morbidity and mortality in injection drug users; in 2000 there was an outbreak of an unexplained illness with extremely high mortality in England determined to be caused by Clostridium novyi. Over 90 percent of the cases were in injection drug users, and the main determinants of infection were being a current injector (P < 0.05) and sharing syringes (P < 0.05) (Bellis et al, 2001). The toxin from Clostridium botulinum manifests in wound botulism, a condition associated with very high mortality rates. Since 1988, areas of California have experienced a significant increase in incidence associated almost exclusively with the injection of black-tar heroin - a black, gummy form of heroin produced in Mexico in makeshift factories proximate to opium poppy fields (Passaro et al, 1998).

The transmission of malaria, a disease caused by the parasite Plasmodium, is commonly associated with the Anopheles mosquito in endemic regions of the world. However, a malaria epidemic among injection drug users was first described as early as 1928 in Egypt (Chau et al, 2002). Researchers at that time theorized that sharing of injection materials was responsible for the epidemic, as the affected group had not come from an area where malaria was endemic. The occurrence of malaria epidemics among injection drug users in non-endemic areas has continued over the last century in various regions throughout the world. A recent study completed in Vietnam demonstrated a similar natural history of malaria in non-HIV-infected injection drug users in comparison with the general population where malaria is transmitted by mosquitoes (Chau et al, 2002). However, among people presenting with the immunosuppressive manifestations of HIV there is higher incidence of malaria, with each episode associated with higher morbidity and mortality (Whitworth and Hewitt, 2005). Furthermore, as malaria has increasing incidence in injecton drug users with higher HIV seroprevalence rates, scientists have expressed concern regarding the development of a more resistant strain of malaria secondary to co-infection with HIV (Bastos et al., 1999).

0 0

Post a comment