Parasites of Blood and Lymphatics (Buxton) Flashcards
Name the 3 protozoans discussed in this lecture.
Plasmodium sp.
Babesia sp.
Trypanosoma sp.
Name the Trematode infection of the blood discussed in this lecture.
Schistosomes
Name the 4 filarial Nematodes discussed in this lecture.
Wuchereria bancrofti
Brugia malayai
Onchocerca volvulus
Loa loa
Why learn about parasites not found in the US?
Immigration
Travel
Military
Medical missions
What is the etiology of malaria?
Plasmodium sp.
P. vivax
P. ovale
P. malariae
P. falciparum
Protozoa that replicate in hepatocytes and RBCs are what species?
Plasmodium
Where is malaria most endemic?
Africa, parts of Central & South America, SE Asia
What percent of deaths of children per year from malaria are due to P. falciparum?
95%
Describe life cycle of mosquitos.
What are the most important stages?
Sporozoites enter and grow in hepatocytes (liver schizonts)
Merozoites - infectious form for RBC
Gametes are sucked up by another mosquito getting blood
Gamates become zygote, becomes oocyte - sporozoites burst out of cyst and move into salivary gland of mosquito
Patient presents with cyclic episodes of high fever, chills, rigors. Prior to this, he complained of experiencing a flu-like illness with headache, loss of appetite, and general malaise about 2 weeks ago.
Malaria
What are the classic signs of malaria?
Explain the pattern of these symptoms.
Cyclic episodes of high fever, chills, rigors.
Due to host cell reaction to rupture of RBC, with release of hemoglobin and other cellular debris, and the release of the parasite antigen, which leads to host secretion of TNF & IL-1.
Do all species of Plasmodium have the same cyclical response to malaria?
No - P. falciparum does not have any periodicity to the classical signs of infection.
P. vivax & P. ovale do - every 48 hours
P. malariae - every 72 hours
______ or ______ involvement can in occur in P. falciparum infections with increased fatality rates.
CNS…renal…
Which species of Plasmodium is the most prevalent, geographically widespread species infecting humans?
P. vivax
Which species of Plasmodium replicates in young RBCs?
P. vivax & P. ovale
Which species of Plasmodium form hypnozoites (dormant form), which are found in the liver?
P. vivax & P. ovale
Which species of Plasmodium replicates in mature RBCs?
P. malariae
What additional drug is needed to treat hypnozoites?
Primaquine
Which species of Plasmodium causes the most severe infection?
P. falciparum
This species of Plasmodium has many strains that are resistant to chloroquine. It replicates in erythrocytes of any age and has more parasite replication and RBC lysis compared to any other Plasmodium species.
P. falciparum
What does P. falciparum do to blood that makes it so dangerous?
Infected RBCs express a protein, pfEMP-1, on their membranes that binds to ICAM-1, an adhesion molecule, on endothelial cells. This leads to RBC blockage of small vessels. This is particularly bad when blood gets blocked from reaching the CNS, kidneys, and placenta.
Cerebral malaria, Blackwater fever, and maternal & fetal death in pregnancy are all severe manifestions of complications due to which species of Plasmodium? What causes these complications?
P. falciparum
Blood blockage
You obtain lab results that show parasites in Giemsa-stained blood smears. You see ring forms, gametocytes, trophozoites, and schizonts. What’s your diagnosis?
Malaria
What is your diagnosis based off of this slide?
Malaria
Ring forms - P. falciparum in RBC
Schizont - P. falciparum in RBC
Gametocyte - P. falciparum in RBC
Ring forms - P. ovale in RBC
Schizont - P. ovale in RBC
Gametocyte - P. ovale in RBC
What can you use to treat chloroquine-resistant P. falciparum?
Mefloquine
Quinine + doxycycline or clindamycin
Atovaquone + proguanil (combo = Malarone)
What can you use to treat chloroquine-sensitive P. falciparum and P. malariae?
Chloroquine
What can you use to treat P. vivax and P. ovale?
Chloroquine + primaquine (for hypnozoites)
What are some methods for control/prevention of malaria?
Insecticides - mosquitos
Repellents, bed nets - mosquito bites
Chemoprophylaxis - best for travelers
What is the best method of prevention for malaria? Why?
Bed nets - biting cycles are worse at night and nets have proven to be extremely effective at protecting people from bites. They’re alse extremely affordable.