Parasitology

What is a Parasite?

one who eats at another’s table or lives at another’s expense

Entamoeba histolytica

Amebiasis

Plasmodium species

Malaria

Trypanosomes

Chagas disease

Babesia

Babesiosis

What is the two groups of human parasites?

protozoa (unicellular) and helminths (worms)

What type of parasite is Entamoeba histolytica?

Intestinal parasite

What is the vector for malaria?

Mosquito

What type of parasite is malaria?

Blood parasite

What is the vector for Chagas disease?

Kissing bugs

What type of parasite is Chagas disease?

Blood parasite

What is the vector for Babesia?

Ticks

What type of parasite is Babesia?

Blood parasite

What severe disease does Naegleria fowleri cause?

Primary Amoebic Meningoencephalitis (PAM)

What is Naegleria fowleri commonly called?

Brain-eating amoeba

Where can Naegleria fowleri be isolated from?

Cerebrospinal fluid (CSF)

What is the usual outcome of Naegleria fowleri infection?

Treatment usually unsuccessful → death

What disease is caused by Acanthamoeba?

Keratitis

What is the main cause of Acanthamoeba keratitis?

Poor contact lens care

What specimen is used to diagnose Acanthamoeba keratitis?

Corneal scrapings

What does Trichomonas vaginalis infect?

Urogenital tract (pathogenic in healthy humans)

How is T. vaginalis transmitted?

Sexually transmitted

Where does T. vaginalis divide in females?

Vagina and urethra epithelial cells

Where does T. vaginalis divide in males?

Urethra, prostate, and seminal vesicles

Name another flagellated protozoan.

Giardia intestinalis (lamblia)

What type of pathogen is Giardia intestinalis?

Intestinal pathogen

What is often the most important method for identifying microorganisms?

Direct microscopic examination

What is ocular micrometry used for?

Measuring the size of microscopic objects

How does ocular micrometry work?

Uses an eyepiece micrometer with an engraved scale in the microscope eyepiece

What type of organism is E. histolytica?

Single-celled protozoa

Who does E. histolytica infect?

Humans and other primates

Are all individuals with amebiasis symptomatic?

No, many are asymptomatic carriers

What intestinal lesion is common in amebiasis?

Ulcers on the colon wall → toxic megacolon

What causes tissue damage in amebiasis?

Lytic enzymes from E. histolytica

Main gastrointestinal symptoms of amebiasis

Abdominal pain, cramps, colitis with diarrhea

Pathophysiology effect of lytic enzymes

Altered host cell membrane permeability and increased intracellular calcium

Severe intestinal amebiasis symptom

Numerous bloody stools per day

What type of organism causes malaria?

Protozoan

What is the genus of the malaria parasite?

Plasmodium

What happens to RBCs infected by P. falciparum?

They adhere to vascular endothelium and adjacent RBCs

What severe complication results from vascular sequestration?

Cerebral malaria (high mortality)

Who is most affected by severe anemia in malaria?

Children and pregnant women (P. falciparum and P. vivax)

What is “Blackwater fever”?

Massive intravascular hemolysis and kidney disease from P. falciparum

What causes the dark/red urine in Blackwater fever?

Hemoglobinuria

How does Blackwater fever urine appear?

Dark red, cola-colored, or “black”

Key features of P. vivax in RBCs?

Ring forms and young trophozoites; large RBCs with Schüffner’s dots

Key features of P. ovale in RBCs?

Enlarged, oval RBCs with Schüffner’s dots; fimbriated (ragged) membrane

Key features of P. malariae in RBCs?

Infects only mature RBCs; cells not deformed; Bar/band forms and rosette schizonts; Ziemann’s dots

: What are Schüffner’s dots?

Pale pink granules in RBC cytoplasm

What are Ziemann’s dots?

Reddish granules seen in RBCs infected with P. malariae

What does T. brucei gambiense & T. rhodesiense cause?

Human African trypanosomiasis or African Sleeping Sickness

What does T. cruzi cause?

American trypanosomiasis or Chagas disease