More Studies Confirm Sexually Transmitted Infections Promote HIV Infection and Disease Progression

Trichomoniasis and HIV Infection

As reported in the March 1, 2007 Journal of Infectious Diseases, researchers from the University of Washington in Seattle and the University of Nairobi conducted a prospective study of women in Mombasa, Kenya, to determine whether trichomoniasis is associated with an increased risk of HIV infection.

Trichomonas (how it looks under a microscope)

Trichomoniasis, caused by the Trichomonas vaginalis parasite, can lead to symptoms such as itching, painful urination, and genital discharge, but usually does not cause serious complications. The standard treatment is oral metronidazole (Flagyl).

The present study, which collected data over 11 years, included 1335 initially HIV negative female sex workers who were followed for a median of about 1.5 years, with monthly laboratory screenings for HIV and genital tract infections.

Results

·      Among the 1335 initially HIV negative women, 806 were diagnosed with new T. vaginalis infections, for an incidence rate of 23.6 per 100 person-years (PY).

·      265 women experienced HIV seroconversion, for an incidence rate of 7.7 per 100 PY.

·      Trichomoniasis was associated with a 1.52-fold increase in the risk of HIV acquisition after adjusting for potential confounding factors such as condom use, contraceptive use, number of sex partners, and presence of other genital infections.

·      Factors associated with incident trichomoniasis were shorter duration of sex work, fewer than 8 years of education, and presence of cervicitis (cervical inflammation) and/or bacterial vaginosis.

·      Regular condom use and use of progesterone-only contraceptives were associated with a lower risk of trichomoniasis.

In conclusion, the authors wrote, “Treatment and prevention of T. vaginalis infection could reduce HIV-1 risk in women.”

In their discussion, the reseachers suggested that trichomoniasis may facilitate HIV infection by causing genital inflammation (in which cells susceptible to HIV infection accumulate in the genital tract), mucosal bleeding, or abnormal vaginal flora; in addition, the parasite appears to inhibit an enzyme that prevents HIV from attaching to cells.

In their discussion, the reseachers suggested that trichomoniasis may facilitate HIV infection by causing genital inflammation (in which cells susceptible to HIV infection accumulate in the genital tract), mucosal bleeding, or abnormal vaginal flora; in addition, the parasite appears to inhibit an enzyme that prevents HIV from attaching to cells.

Syphilis and HIV Disease Progression

In the March 1, 2007 Journal of Acquired Immune Deficiency Syndromes, Spanish researchers reported results from a study assessing the effect of syphilis on HIV viral load and CD4 cell count.

Caused by the bacterium Treponema pallidum, syphilis causes a variety of symptoms. Primary or early syphilis is characterized by painless genital sores known as chancres; these usually heal without treatment, but the bacteria remain in the body. Secondary syphilis is characterized by a skin rash, including the palms and soles; patients may also experience flu-like symptoms. Tertiary or late syphilis can damage organs including the brain, heart, and eyes, potentially leading to blindness and dementia. Standard treatment for early syphilis is a single injection of benzathine penicillin.

The present retrospective study included 118 HIV positive participants (96% men, mean age 38 years) at 12 hospitals in Spain who were diagnosed with early syphilis between January 2004 and December 2005. Half were on antiretroviral therapy at the time syphilis was diagnosed; those who started HAART or changed their antiretroviral regimen during the observation period were excluded from the analysis. 76 subjects had viral load and CD4 cell measurements available before and during syphilis infection; 94 had measurements available during infection and after treatment.

Results

·    HIV and syphilis were diagnosed at the same time in 38 patients (32%).

·    CD4 cell counts were lower during syphilis infection than 3-9 months before infection (590 vs 496 cells/mm³;
    
·    CD4 counts rose again after syphilis treatment (from 509 to 597 cells/mm³; P = 0.0001).   

·    HIV viral load increased in 27.6% of patients during syphilis infection:

o    33% of patients with prior detectable HIV had viral load increases;
o    25% with previously suppressed HIV demonstrated detectable viral loads.     

·    Viral load did not decline after syphilis treatment.
  
·   The only factor associated with increased viral load was lack of HAART.
   
·   The only factor associated with a CD4 count decrease of more than 100 cells/mm³ during syphilis infection was prior CD4 cell count.

Conclusion

"Syphilis infection was associated with a decrease in the CD4 cell count and an increase in the HIV viral load in almost one third of the patients," the authors wrote.

They also noted that, "In this series, more than two thirds of the syphilis cases were diagnosed in patients who were previously known to be infected with HIV" -- indicating that HIV positive individuals were continuing risky sexual behavior.

These 2 studies -- as well as recent research on the connection between herpes simplex virus and HIV transmission -- indicate that screening and treatment of STIs is an important component of HIV prevention and management.

Highlighting the importance of this topic, 2 review articles discussing various issues related to HIV and STIs -- including recent outbreaks of lymphogranuloma venereum and drug-resistant gonorrhea -- were published recently, one by Jeanne Marrazzo, MD, in the February-March 2007 issue of Topics in HIV Medicine (also available as a webcast at www.iasusa.org), the other by Nicola Zetola, MD, and Jeffrey Klausner, MD, in the May 1, 2007 issue of Clinical Infectious Diseases.

04/13/07

References

RS McClelland, L Sangare, WM Hassan, and others. Infection with Trichomonas vaginalis Increases the Risk of HIV-1 Acquisition. Journal of Infectious Diseases 195(5): 698-702. March 1, 2007.

R Palacios, F Jimenez-Onate, M Aguilar, and others. Impact of syphilis infection on HIV viral load and CD4 cell counts in HIV-infected patients. JAIDS 44(3): 356-359. March 1, 2007.

J Marrazzo. Syphilis and Other Sexually Transmitted Diseases in HIV Infection. Topics in HIV Medicine. 15(1): 11-16. February-March 2007.

NM Zetola and JD Klausner. Syphilis and HIV Infection: An Update. Clinical Infectious Disease. 44(9): 1222-1228. May 1, 2007.