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Toronto Notes 2019 Protozoa – Intestinal/Genitourinary Infections Giardia lamblia
Etiology
• infectionwithG.lambliaoccursviathefecal-oralroutewiththeingestionofcystsfromwater/food contaminated by infected humans and other mammals (especially in the Rockies)
• riskfactors:travel,camping,institutions,daycarecentres,MSM
Clinical Presentation
• giardiasis(“beaverfever”)
■ symptoms vary from asymptomatic to self-limited mild watery diarrhea to malabsorption syndrome
(chronic giardiasis where the parasite coats the small intestine and thus prevents fat absorption) ■ nausea, malaise, abdominal cramps, bloating, flatulence, fatigue, weight loss, steatorrhea
■ no hematochezia (no invasion into intestinal wall), no mucous in stool
Investigations
• multiplestoolsamples(dailyx3d)formicroscopy,stoolantigenusedoccasionally • occasionallysmallbowelaspirateorbiopsy
Treatment and Prevention
• metronidazole;nitazoxanideifsymptomatic
• goodpersonalhygieneandsanitation,waterpurification(iodinebetterthanchlorination),outbreak
investigation
Trichomonas vaginalis
Etiology
• infectionwithT.vaginalisoccursviasexualcontact
Clinical Presentation
• oftenasymptomatic(10-50%),especiallymales(occasionallyurethritis,prostatitis)
• Trichomonasvaginitis(seeGynecology,GY25)
• vaginaldischarge(profuse,malodourous,yellow-greenorgrey,frothy),pruritus,dysuria,dyspareunia
Investigations
• wetmount(motileparasites),antigendetection,culture • urinePCRtodetectinmales
Treatment
• metronidazoleforpatientandpartner(s)
Cryptosporidium spp.
Etiology
• infectionwithCryptosporidiumspp.viathefecal-oralrouteoccurswiththeingestionofcystsfrom water contaminated by infected humans and other animals (including cows)
• riskfactors:summerandfall,youngchildren(daycare),MSM,contactwithfarmanimals, immunodeficiency
Clinical Presentation
• rangefromself-limitedwaterydiarrhea(immunocompetent)tochronic,severe,non-bloody diarrhea with nausea/vomiting, abdominal pain, and anorexia resulting in weight loss and death (immunocompromised)
Investigations
• modifiedacid-faststainofstoolspecimen,microscopicidentificationofoocystsinstoolortissue,stool antigen detection by direct fluorescent antibody
Treatment and Prevention
• supportivecare
• inHIV+patients,(re)initiateARTandtrytoincreasetheirCD4countto>100;iffails,trynitazoxanide
or macrolides
• goodpersonalhygiene,waterfiltration
Infectious Diseases ID37
Trichomonascauses25%ofvaginitis