12.12.05 Traveller illnesses

Travel history

• • When

  • Where

  • What

  • Who

  • How

Food poisoning organisms

• • Salmonella

  • Shigella

  • Campylobacter

Parasites

• • Investigations

    • Haemolysis

      • Very high bilirubin

      • Low Hb

    • May have slightly raised ALT, but not enough to explain the bilirubin

    • Thrombocytopaenia

    • Low glucose

    • DIC

    • Acidosis

  • Parasites are transient and correlate with fever

    • Do the blood film at the appropriate time

    • Do three before deciding it's negative

HIV

• • Common infections are CD4-dependent ones

    • Viruses

    • Protozoa

    • Fungi

    • Mycobacteria

  • Some bacteria too

    • Salmonella

    • Pneumococci

  • Parameters

    • CD4 => Disease stage

      • >200 => Only high-grade infections

      • <200 => Low-grade infections

      • <100 => Very low grade infections

    • Viral load => Speed of progression

  • Acute seroconversion

    • Treatment is not helpful

    • Extremely infectious

  • TB

    • CD4 <200 => Probably reactivation

      • Consolidation with cavitation

      • Air bronchograms

    • CD4 <100 => Probably primary

      • Adenopathy

        • Loss of paratracheal stripe

      • Low zone

      • No cavitation

Low-grade infections in HIV

• • PCP

    • CXR often normal early on

    • Fine reticular (ground-glass) appearance later on

    • Thin-walled cysts

      • Predispose to pneumothoraces

    • Alveolar exudate

  • Candida

    • Oral candida can invade oesophagus

  • Cryptosporidium

    • Colitis - "Dilated, featureless bowel)

      • Thickened bowel wall (check opposed bowel loops)

      • Thumb printing

      • Loss of haustra

    • Remember to check for HIV before you diagnose IBD, as they can look similar

  • CMV retinitis

    • Reactivation of latent herpesvirus

    • Prevalence approx. equal to age in the healthy population

    • Haemorrhagic retinitis

  • Crytococcal meningitis

    • May not see any white cells in CSF, despite bacteria due to immunosuppression (sinister sign)

    • Check India Ink stain or CrAg in blood/CSF

  • Toxoplasma

    • Ring-enhancing lesions on MRI

      • Similar to bacterial pyogenic abscess

      • Distinguish by clinical presentation

    • Especially in unusual places

      • Thalamus, basal ganglia

  • Primary cerebral lymphoma

    • Looks very similar to toxoplasma

    • Treat as if toxoplasma and see if it changes

  • TB meningitis

    • Tends to affect the basal system rather than peripheral structures

      • Basal cisterns etc

      • => Cranial nerves often involved

    • Chronic/insidious onset

  • Progressive multifocal leucoencephalopathy (PML)

    • White matter lesions - Look a bit like MS

  • Malignancy

    • Karposi sarcoma

    • Viral leukaemia

Notes

• • Information website - nathnac.org

  • Typhoid test is a blood culture, not stool

  • Cutoff for CD4-dependent infection = 200

  • Lobar pneumonias are often pneumococcal

  • Aspiration pneumonia usually goes to the right middle lobe

  • First seizure in an adult = SOL UPO