This episode begins organism-specific parasitology with protozoa that primarily infect the gastrointestinal and urogenital tracts. Drawing from Murray’s Chapter 72, it explores transmission, pathogenesis, and clinical presentation.
Key intestinal protozoa include:
Giardia lamblia - malabsorption and chronic diarrhoea
Entamoeba histolytica - invasive colitis and liver abscess
Cryptosporidium species - watery diarrhoea, severe in immunocompromised hosts
In the urogenital tract:
Trichomonas vaginalis - sexually transmitted infection causing vaginitis and urethritis
Transmission occurs through contaminated water, food, faecal–oral spread, or sexual contact. Many infections remain luminal, but some protozoa invade mucosa and disseminate.
Conceptually, these organisms demonstrate how single-celled parasites can produce both localised and invasive disease. Clinically, travel history, water exposure, and sexual history guide suspicion.
Key Takeaways
Intestinal protozoa are commonly waterborne
Giardia causes malabsorption
Entamoeba can cause invasive colitis and liver abscess
Cryptosporidium causes severe disease in immunocompromised hosts
Trichomonas is sexually transmitted
