Trichomonas vaginalis (TV) is one of the most successful protozoan pathogens and the most common non-viral sexually transmitted disease, responsible for around 180 million new infections worldwide every year. Presentation in females is usually profuse, purulent, malodorous vaginal discharge and vaginal irritation, although infection can be subclinical or asymptomatic. TV may also be associated with inflammation of the cervix (strawberry cervix) that may mimic the cervical tenderness associated with pelvic inflammatory disease (PID).  Changes in the cervical cells in women with TV have been likened to the changes seen in early cervical intraepithelial neoplasia (CIN), while in men the infection often presents as urethritis and prostatitis

Greenwell, P.

Rughooputh, S.

WestminsterResearch

     University of Westminster Eprints http://eprints.wmin.ac.uk   Trichomonas vaginalis: an irritating protozoan or an important viral co-factor.  Pamela Greenwell Sanjiv Rughooputh School of Biosciences    This is an electronic version of an article published in The Biomedical Scientist, 48(1), pp. 40-41, January 2004.      The Eprints service at the University of Westminster aims to make the research output of the University available to a wider audience.  Copyright and Moral Rights remain with the authors and/or copyright owners. Users are permitted to download and/or print one copy for non-commercial private study or research.  Further distribution and any use of material from within this archive for profit-making enterprises or for commercial gain is strictly forbidden.        Whilst further distribution of specific materials from within this archive is forbidden, you may freely distribute the URL of the University of Westminster Eprints (http://eprints.wmin.ac.uk).   In case of abuse or copyright appearing without permission e-mail wattsn@wmin.ac.uk.  Trichomonas vaginalis (TV) is one of themost successful protozoan pathogens andthe most common non-viral sexuallytransmitted disease, responsible foraround 180 million new infectionsworldwide every year.1 Presentation infemales is usually profuse, purulent,malodorous vaginal discharge and vaginalirritation, although infection can besubclinical or asymptomatic.2 TV may alsobe associated with inflammation of thecervix (strawberry cervix) that maymimic the cervical tenderness associatedwith pelvic inflammatory disease (PID).3Changes in the cervical cells in womenwith TV have been likened to the changesseen in early cervical intraepithelialneoplasia (CIN), while in men theinfection often presents as urethritis4and prostatitis.5For many years, TV infection has been seensimply as an irritating protozoan that wasrelatively easy to treat. Recently, however,there has been evidence to implicate TV inpre-term delivery, low birthweight, infantmortality and predisposition to humanimmunodeficiency virus (HIV) infection andcervical cancer.6 Although all these areas areinteresting, this article will only review thelinks between TV and HIV. Classical studyT. vaginalis is a classical parasite that harvestsalmost all its nutrients and needs from itshost. To accomplish such a task, TV produceshydrolases to break down host proteins,oligosaccharides, DNA and lipids to obtainthe building blocks with which to reconstructits own macromolecules.7-10In its quest for these building blocks, TV produces a range of highly active enzymesthat also destroy the protective mucin of thehost’s urogenital tract, allowing the TV toattach to the underlying cells and causelesions. These then provide a portal of entryfor HIV, which, under normal circumstances,does not easily infect females. Indeed,heterosexual intercourse with a man infected with HIV only carries a 1% risk ofHIV transmission. Draper et al.11 studied the effect of TV onsecretory leucocyte protease inhibitor (SLPI),which protects against viral infection, andfound that the inhibitor was non-functional in vaginal secretions due to the action ofcysteine proteinases secreted by thetrichomonads. Studies from Africa have shown that therate of HIV transmission is increased two-foldin women with TV. In a study in four cities insub-Saharan Africa, Buve et al.12 found acorrelation between the prevalence of TV and HIV. The prevalence of trichomoniasiswas higher in cities where there were ahigher number of HIV-positive individuals(31.8%) compared to cities where HIVincidence was lower (TV prevalence 10.4%).Sorvillo et al.13 calculated that, if TV infectionamplifies transmission of HIV by a factor ofTrichomonas vaginalis:an irritating protozoan or an importantviral co-factor?THE BIOMEDICAL SCIENTIST   January 200440TriPath Imaging Characteristic forms of Trichomonas vaginalis (arrowed) in a liquid-based cytologypreparation from the cervix. ‘Studies from Africahave shown that therate of HIVtransmission isincreased two-fold inwomen with TV’ARTICLEFor many years, Trichomonas vaginalis has been regarded simply as an irritating but easily treatable protozoan; however, recent research implicates it in a range of problems from pre-term delivery to human immunodeficiency virus infection andcervical cancer. Here, Sangiv Rughooputh and Pamela Greenwell review the evidence. two in a country where the prevalence of TVis 25% (a level common in parts of Africa),then 20% HIV transmission could beattributed its presence. Taboo subjectFrom an economic standpoint, treatment ofTV infection is cheap and readily available,whereas treatment for HIV is outside thereach of poor communities; thus, diagnosisand therapy for TV are vital. With reports of emerging strains resistant to metronidazole– the drug of choice for the treatment of TVinfection – fewer patients clear infections andthus are susceptible to the formation oflesions, making the penetration of othersexually transmitted infections (STIs) easier.Clearly, an understanding of the pathogenicityof sexually transmitted organisms and theirinteractions should allow development of newdiagnostic and treatment regimes. Sadly, discussion about STIs remains taboo; there is a stigma attached to theiracquisition, and reluctance, both bygovernments and individuals, to discuss thescale of the problem. Nonetheless, it may bepossible to reduce levels of infection througheducation and the development of newtreatments. In the UK, however, where thereis access to education, confidentialcounselling and screening, and freemedication, there has been an upsurge in thenumbers of cases of STIs reported. Continuing questIn the quest to eradicate sexually transmitteddiseases, including HIV, the UK MedicalResearch Council (MRC) will benefit fromfunding of some £16 million from theDepartment for International Developmentover the next five years. In a move likely toprovide a breakthrough in the treatment andprevention of STIs, government agencies inthe USA allocated $60 million in 2001 forthe development of microbicides and, in theUK, ML Laboratories is to start an MRC-funded trial of a product that disruptsorganism binding.14Such microbicides could provide a safe andundetectable barrier to infection for womenwho currently cannot persuade their partnersto use a condom. An alternative in the formof the female condom has been singularlyunacceptable and very costly. Thus, the useof microbicides could bring about a change in responsibility for protection and result inwomen having the responsibility to safeguardtheir sexual health. More than just an irritation?If TV infection predisposes to HIV, does italso permit access of other viruses to theurogenital tract? Recent work by Sayed el-Ahlet al.15 showed that in 48 patients withinvasive cervical cancer and 100 random age-matched controls, 19% and 5%, respectively,had antibodies to TV, suggesting that, at somestage, the cancer patients had contact withTV. Patients with TV infection had a three-fold increased likelihood of contractingcervical cancer, hence TV can be categorisedas an important co-factor in the pathogenesisof cervical cancer. Since there is a strongproven link between cervical cancer andhuman papillomavirus, is TV a co-factor inthe acquisition of this virus? In conclusion, one thing is crystal clear; TV is not just an irritating protozoan! REFERENCES1 Chavalitshewinkoon-Petmitr P, Ramdja M,Kajorndechakiat S, Ralph RK, Denny WA,Wilairat P. In vitro susceptibility of Trichomonas vaginalis to AT-specificminor groove binding drugs. J AntimicrobChemother 2003; 52: 287–9. 2 Burja IT, Shurbaji MS. Clinical impact of identifying Trichomonas vaginalis oncervicovaginal (Papanicolaou) smears.Diagn Cytopathol 2001; 4: 195–9. 3 Moodley P, Wilkinson D, Connolly C,Moodley J, Sturm AW. Trichomonasvaginalis is associated with pelvicinflammatory disease in women infectedwith human immunodeficiency virus. CID 2002; 34: 519–22. 4 Krieger JN, Verdon M, Siegel N, HolmesKK.. Natural history of urogenitaltrichomoniasis in men. J Urol 1993; 149:1455–8. 5 Ohkawa M, Yamaguchi K, Tokunaga S,Nakashima T, Shinichi F. The incidence of Trichomonas vaginalis in chronicprostatitis patients determined by cultureusing a new modified liquid medium. J Infect Dis 1992; 166: 1205–6. 6 Dunne RL, Dunn LA, Upcroft P,O’Donoghue PJ, Upcroft JA. Drugresistance in the sexually transmittedprotozoan Trichomonas vaginalis. Cell Res 2003; 13: 239–49. 7 Lockwood BC, North MJ, Scott KI. The use of a highly sensitiveelectrophoretic method to compare theproteinases of trichomonads. Mol BiochemParasitol 1987; 24: 89–95. 8 Alderete JF, Newton E, Dennis C, NealaKA. The vagina of women infected withTrichomonas vaginalis has numerousproteinases and antibody to trichomonadproteinases. Genitourin Med 1991; 67: 331–4. 9 Connaris S, Greenwell P.. Glycosidases in mucin-dwelling protozoans. Glycoconj J1997; 14: 879–82. 10 Das S, Stevens T, Castillo C, VillasenÇ’r A,Arredondo H, Reddy K. Lipid metabolismin mucus-dwelling amitochondriateprotozoa. Int J Parasitol 2002; 32:655–75. 11 Draper D, Donohoe W, Mortimer L, HeineRP. Cysteine proteases of Trichomonasvaginalis degrade secretory leucocytesprotease inhibitor. J Infect Dis 1998; 178:815–9. 12 Buve A, Weiss HA, Laga M et al. The epidemiology of trichomoniasis inwomen in four African cities. AIDS 2001;15 (Suppl 4): S89–96. 13 Sorvillo F, Smith L, Kerndt P, Ash L.Trichomonas vaginalis, HIV and African-Americans. Emerg Infect Dis 2001; 7: 927–32. 14 Stone A. Protect and survive. NewScientist 2003; 177 (2381); 42–4.15 Sayed el-Ahl SA, el-Wakil HS, Kamel NM,Mahmoud MS. A preliminary study on therelationship between Trichomonasvaginalis and cervical cancer in Egyptianwomen. J Egypt Soc Parasitol 2002; 32:167–78. 41THE BIOMEDICAL SCIENTIST   January 2004Sangiv Rughooputh and Pamela Greenwellare members of the molecular and medicalmicrobiology research group in the Schoolof Biosciences, University of Westminster,London. ‘Treatment of TV infection is cheap andreadily available, whereas treatment for HIVis outside the reach of poor communities’‘TV can becategorised as animportant co-factor inthe pathogenesis ofcervical cancer’CompanyMembershipCommercial organisations andinstitutions are invited to jointhe Institute as CompanyMembers. They can therebyjoin biomedical scientists in working to improve standardsand communications in thepathology laboratory field.Company Members can maketheir views know through aliaison group.A brochure is available onrequest to the IBMS at 12 Coldbath Square, LondonEC1R 5HL, tel 020 7713 0214,mail@ibms.org.

Trichomonas vaginalis: an irritating protozoan or an important viral co-factor

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Trichomonas vaginalis: an irritating protozoan or an important viral co-factor

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