Parasitology I (Amebiasis, Balantidium, Leishmania, & Malaria) Flashcards
What parasite causes amebiasis?
Entamoeba histolytica
Which Entamoeba is pathogenic?
histolytica
Which entamoeba is nonpathogenic?
dispar
What is the infective stage of amebiasis?
cyst
What is the pathology stage of amebiasis?
trophozoite
How is amebiasis transmitted?
fecal contaminated food and water; anal-oral sex
Where does amebiasis act?
large intestine, liver, CNS
What are the GI symptoms of amebiasis?
bloody diarrhea, watery diarrhea, constipation and then diarrhea
What is the GI pathology of amebiasis?
ulcers
What are the liver symptoms of amebiasis?
pain in the right quadrant; takes months or years to develop into an abscess
Why are the liver symptoms a time bomb?
because 60% of people with liver involvement never remember having any GI problems
What common organelles are missing in Entamoeba histolytica?
mitochondira, endoplasmic reticulum (ER), golgi apparatus, microtubules
What is the main host of Balantidium Coli?
pig
What two stages does Balantidium coli have?
trophozoite and cyst
What is special about the trophozoite stage?
it has cilia
What is the infective stage of Leishmania?
from the Sandfly
What is the pathology stage of Leishmania?
the amastigote
Where does Leishmania affect the human body?
depends on the type
How is Leishmania transmitted?
bite of sandfly
How is Leishmania diagnosed?
dipstick, biopsy, and culture
How is Leishmania treated?
toxic drugs
What is the vector for Leishmania?
the sandfly
What is cutaneous leishmaniasis?
- A simple skin lesion in skin where infected sandfly had previously bit the person
- 1 infected bite = 1 lesion
What is diffuse cutaneous leishmaniasis?
when a person has a defect in their cell mediated immune system the lesions can develop all over the skin of the body
What is mucocutaneous leishmaniasis?
lesions in the mucocutaneous tissues of the mouth, nose, and genital areas
What is visceral leishmaniasis?
lesions in the spleen, liver, and bone marrow
What are the symptoms of visceral leishmaniasis?
- fever
- hepatosplenomegaly
- anemia
- hypergaminaglobulinemia (polyclonal B cell activation) - cause of anemia - antibodies coat normal RBC’s that are lysed
Is leishmania zoonotic?
yes, many different wild animals are infected including rodents, sloths, and domestic dogs
What is the the relationship between HIV & leishmania?
visceral leishmaniasis is more pathogenic in HIV-infected people
What is the original theory of transmission for malaria?
inhaling bad (mal) air (aira) from swamps
What are some of the malaria species?
- Plasmodium falciparum
- P. vivax
- P. malariae
- P. ovale (rare and like vivax)
- P. knowlesi (normally in monkeys but now find a problem in humans)
What is the vector for malaria?
Anopheles sp. of mosquitoes
What are the stages of malaria in the liver?
- sporozoite
- exoerythrocytic schizont (EE stage) - in all 5 species of malaria w/ developing merozoites
- hypnozoite (only P. vivax and P. ovale) - a slow growing EE stage
How is malaria treated?
- Prophylaxis = ACT drugs - a combination of Artemisinin and another drug
- Primaquine
What do ACT drugs target?
they only kill blood stages
What does Primaquine target?
it kills hypnozoites
What is the problem with primaquine?
it’s toxic, so it can’t be given before travel, only for treatment when you return with P. vivax to kill hidden hypnozoites
What organelle is used for entry into RBC’s?
merozoite
What are the stages of malaria in RBC’s?
- merozoites
- rings (young trophozoites)
- trophozoites (mature)
- schizonts (once nucleus divides)
- gametocytes (sexual stages)
~ microgametocytes - male
~ macrogametocytes - female
What are the symptoms of malaria?
- fever
- anemia
- splenomegaly
What are the complications of P. falciparum?
- anemia
- severe anemia
- hyperparasitemia
- hyperthermia diarrhea
- hypoglycemia acidosis
- death
- cerebral malaria
- renal failure
- pulmonary edema
Who dies from malaria?
- children
Who lacks immunity?
- young children
- people that have never been infected
What is premunition immunity?
- people are immune as long as they have a low grade infection
- when you lose your parasites you lose your immunity
What RBC variants confer resistance?
- hemoglobinopathies
- RBC enzyme variants
- RBC membrane variants
How is sickle cell anemia related to malaria?
- children w/ SS die
- children w/ AS have a 70-fold less risk of severe malaria
- children w/ AA have normal Hb
What is normal oxygen tension?
parasite grows well in AA, AS, and SS, but when parasites get sequestered in capillaries the oxygen tension drops and lowers pH which causes sickling and parasitized cells die
What is the new mechanism of sickle cell protection against malaria?
parasitized AS & AC RBC’s show similar reduction in surface PfEMP-1 expression & in adherence to endothelial cells lining blood vessels
How does malaria affect pregnancy?
- increased risk of severe pathology during 1st pregnancy in infected mother
- cerebral malaria risk is increased
- low birth weight is common (these children often don’t develop normally)
How is malaria diagnosed?
blood films and dipsticks
How are different blood films used in diagnosing malaria?
- thick is to find parasites
- thin is to speciate for proper treatment
What dipsticks are used to diagnose malaria?
- antigen capture tests
- OptiMAL - follow drug treatment
- determine
How does malaria affect those with HIV?
- increase in viral load in macrophages in HIV patients that have an active malaria infection
- the viral load goes down after treatment for malaria
- increased viral genotypic heterogeneity & CD4 lymphocyte loss leading to accelerated decline in immune function
What is malariotherapy for human HIV?
- infect patients with P. vivax
- induce high levels of cytokine activities & change T-lymphocyte subsets & phenotypes in HIV patients
- may help HIV-infected patients whose CD4 baselines are in the range of 200-500
- need much larger studies to confirm findings
