Infectious Disease -- Parasites I - Protazoa Flashcards
What are protazoa?
Single-celled organisms with complex cytoplasmic oranelles; most motile
Are protazoa intra or extracellular?
Both
Most protazoa are spread by…
Fecal Oral
Some by insect bites, entry through the skin
Normal protazoa life cycle
Adult motile form and cyst form
Characteristically intestinal
Usually commensals that cause no disease
Two protazoa with complex life cycles?
Malaria and Trypanosomiasis
Tissue destruction with protazoa is caused by…
Invasion of host tissues by the organism
NOT the immune responses
IgE is used to kill…
Multicellular organisms (not protazoa)
Four main kinds of malaria? Who is worst?
- Falciparum, vivax, ovale, malariae
- Falciparum
Two types of resistance that are messing up malaria treatment?
DDT resistant mosquitos
Chloroquine resistant Falciparum
Clinical features of all malaria forms?
Anemia, Fever
Describe the malaria life cycle from bite to exiting liver
Sporozoites released into the blood w/ mosquito bite
Invade the Liver
Rapidly form thousands of merozoites
Hepatocyte ruptures, releasing merozoites
Describe the malaria life cycle from liver exit to bite
Merozoites bind sialic residues on RBCs
Multiply in RBCs
Cells rupture and release more merozoites
In RBCs, for ringed, trophozoite ringed form
Some form gametocytes, which infect the mosquito on blood meal
What markers to malaria protazoa use to find the liver
Thrombospondin and Properdin receptors
How do malaria protazoa detoxify heme?
Which drug prevents this?
Forming a paracrystaline precipitate (hemozoin
Chloroquine
What structural change occurs with falciparum matures to schizont form?
Display sequestrins which bind to ICAM-1 on endothelial cells
Display thrombospondin receptor and CD46
____ Confers some immunity to malaria infected Hepatocytes via T-cell mediated response
HLA-B53
RBC changes that alter malaria infectivity include…
Duffy-negative African Americans
Sickle RBCs change shape on infection (early spleen isolation)
Problem with malaria schizont form
They’re inflexible
They don’t enter the spleen
Can cause splenomegaly + hepatomegaly
Hemolysis of infected RBCs causes what noteable symptoms
Hemoglobinuria (Black Water Fever)
Kidney Damage
What does free hemoglobin do to the organs?
Pigmentation
Esp. in Kupfer cells
Effects of falciparum
Severe anemia, renal failure, pulmonary edema, cerebral symptoms, and death
What causes the higher parisitemia of falciparum
Infection of all ages of RBCs
How does falciparum tend to kill you?
Especially in kids
Cerebral Involvement
Species specific details for vivax and ovale
Not life threatening (usually)
Infection of reticulocytes
Specific details for P. malariae
Non-life threatening (usually)
Mature RBCs
low grade parasitemia that can last up to 40 years
Glomerulonephritis
What does a malaria spleen look like?
Congested and Enlarged
In chronic infection – fibrotic and brittle w/ thick capsule
Gray/Black parenchyma (from RBC, debris, and hemozoin)
What does a malaria Liver look like?
Progressively enlarged and pigmented (mostly Kupfer cells)
What does a malaria Kidney look like?
Enlarged, congested with pigment and hemoglobin casts
What does a malaria heart look like?
Focal hypoxic lesions (progresive anemia and circulatory stasis)
What does a falciparum brain look like?
Vessels plugged with parasitized cells
Ring hemorrhages focal ischemia and softening
Small focal inflammatory reactions (malarial and Durck’s granulomas)
What is the major toxin of Eosinophils?
Major basic Protein
Puts holes in the big invaders
Describe microscopic appearance of brain capillary in Falciparum infection
Obstructed
RBCs look like they have nuclei, but they’re actually schizonts
What is Winterbottom’s sign?
Pronounces lymphadenopathy seen in African Sleeping Sickness
Parasites that disseminate in immunosuppressed individuals
Cryptosporidiosis
Toxoplasmosis
Four parasite tissue invaders
Toxoplasmosis
Leishmaniasis
Naegleria
Acanthoameba
Leishmaniasis is almost the same as sleeping sickness. Where do they differ
Trypanosomiasis – RBC
Leishmaniasis – Macrophages
What does IL-4 do?
Promotes IgE production
What does Il–5 do?
Stabilizes Eosinophil population
What parasite is associated with Cholangiocarcinoma?
Liver flukes
Four small intestinal parasites
Giardia
Hookworm
Strongyloides
Ascaris
Onchocerca volvulus is also known as…
River Blindness
Body/Head Lice are vectors of…
Ricketsia prowazeki
Trench fever (Rochalimaea quintana)
Borrellia recurrentis
What to know about crab louse?
Sexually Transmitted Ectoparasite
Causes “Blue spots”, painless, don’t disappear with pressure, in deeper tissues. Last several days after bite where poisonous saliva is injected.
Symptoms of scabies?
Intense pruritis lesions mediated by IgE
Recurs every month when locally laid eggs hatch
What are chiggers?
Larvae of mites that take of residence in hair follicles
Why do chiggers itch?
They inject a digestive enzyme that ruptures cells, causing an intense local inflammatory response
How do people get Rhinosporidiosis?
Traumatic inoculation of organism from water source
Symptoms of Rhinosporidiosis?
Granulomatous tissue in MM –> Polyp formation
Infection of nose, nasopharynx, conjunctiva
