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Toronto Notes 2019 Blood and Tissue Infections Investigations
• wetprepandGiemsastainofthickandthinbloodsmear,serology,PCR
Treatment and Prevention
• acute:nifurtimoxorbenznidazole
• indeterminate:increasingtrendtotreatasacuteinfectionforchildrenandadultsunderage50years • chronicdeterminate:symptomatictherapy,surgeryasnecessaryincludinghearttransplant,
esophagectomy, and colectomy; there may be a benefit to antiparasitic treatment • insect control, bed nets
Toxoplasma gondii
Etiology
• infectionwithT.gondiioccursthroughexposuretocatfeces(oocysts),ingestionofundercooked meat (tissue cysts), vertical transmission, organ transplantation, gardening without gloves (cat oocyst exposure), whole blood transfusions, contaminated water sources
Clinical Presentation
• congenital
■ resultofacuteprimaryinfectionofmotherduringpregnancy(TORCHinfection)
■ stillbirth (rare), chorioretinitis, blindness, seizures, severe developmental delay, microcephaly ■ initiallyasymptomaticinfantmaydevelopreactivationofchorioretinitisasadolescentoradult
blurred vision, scotoma, ocular pain, photophobia, epiphora, hearing loss, developmental delay • acquired
■ usually asymptomatic or mononucleosis-like syndrome in immunocompetent patient
■ infection remains latent for life unless reactivation due to immunosuppression • immunocompromised(mostcommonlyAIDSwithCD4<200)
■ encephalitis with focal CNS lesions seen as single or multiple ring-enhancing masses on CT (headache and focal neurological signs)
■ lymph node, liver, spleen enlargement, and pneumonitis
■ chorioretinitis
Investigations
• serology,CSFWright-Giemsastain,antigenorDNAdetection(PCR);pathologyprovidesdefinitive diagnosis
• immunocompromisedpatients:considerCTscan(ring-enhancinglesionincortexordeepnuclei)and ophthalmologic examination
• negativeserologyinmanyAIDSpatients(falsenegativeduetodecreasedlymphocytepopulation)
Treatment and Prevention
• no treatment if: immunocompetent, not pregnant, no severe organ damage
• pregnancy:spiramycintopreventtransplacentaltransmissionorpyrimethamine+sulfadiazine(add
folinic acid), avoid undercooked meat and refrain from emptying cat litter boxes • HIV: TMP/SMX
• properhandhygiene,cookmeatthoroughlytopropertemperature
Infectious Diseases ID39
Mefloquine for Preventing Malaria During Travel to Endemic Areas
Cochrane DB Syst Rev 2017;CD006491. Objectives: To summarize efficacy and safety
of mefloquine used as prophylaxis for malaria in travellers.
Methods: RCTs (for efficacy and safety) and non- randomized cohort studies (for safety) to compare prophylactic mefloquine with placebo, no treatment, or alternative antimalarial agent.
Results: Participants were more likely to discontinue mefloquine (6%) vs. atovaquone- proguanil (3%) due to adverse effects (including nausea, vomiting, abnormal dreams, insomnia, anxiety, and depressed mood during travel).
No difference in serious adverse effects or discontinuation due to adverse effects was found between mefloquine and doxycycline or mefloquine and chloroquine.
Conclusions: Absolute risk of malaria during short-term travel appears low with mefloquine, doxycycline, and atovaquone-proguanil therapy. Choice of agent depends on how individual travellers assess importance of specific adverse effects, pill burden, and cost.
1/3 of Ontario’s population is infected with
Toxoplasma gondii
Classic Triad of Congenital Toxoplasmosis
• Chorioretinitis
• Hydrocephalus
• Intracranial calcifications
Cat ingests mouse with parasite
Mouse (intermediate host)
Livestock (ingestion of poorly cooked meat)
Cat (required for completion of sexual cycle)
Sheds resistant oocysts in stool
Sporozoites
Direct ingestion (handling kitty litter)
Figure 14. Life cycle of Toxoplasma gondii
© Doris Leung