Exam 4 parasites Flashcards
What is the vector for Chagas’ disease
Kissing bug (traitomine insect)
What is the vector for African Sleeping Sickness
TseTse fly
How does toxoplasmosis infect someone?
through ingestion of cysts
What is the vector for river blindness (onchocerciasis)
Black fly
What is the vector for babesiosis?
Deer tick (I. scapularis)
What is the vector of leishmaniasis?
Sand fly
What is the vector for lymphatic filariasis (elephantiasis)?
Mosquito
What is the treatment of Onchocerciasis?
invermectin
What is the larval stage of onchocerciasis that infects humans?
L3 larvae
Where does onchocerciasis mature and sexually reproduce?
Under the skin of the human host
What is the target of ivermectin? What’s it used for?
unsheathed microfilariae which are the offspring of adult sexual reproduction, onchocerciasis
Where is onchocerciasis endemic to?
Sub-saharan Africa
What is the species that causes onchocerciasis?
Onchocerca volvulus
What are the symptoms of onchocerciasis?
Nodules under the skin, hyper pigmented skin (post inflammatory response), severe itching, eye lesions, skin lesions, keratitis
How is onchocerciasis positively diagnosed
skin snip method
What is one way that has proved useful to eliminate onchocerciasis as a public health problem?
Mass drug administration
What is the mechanism of action of ivermectin? What’s it used for?
binds to and blocks glutamate-gated chloride channels that are present in invertebrate muscle and nerve cells; onchocerciasis
What are the classic signs of leishmaniasis?
Ulcerative skin lesions with raised outer border, mucocutaneous lesions, marked splenomegaly
What stage of leishmania infects humans?
promastigote
What is required by leishmania promastigotes to achieve mammalian life cycle stage?
phagocytosis by macrophage to replicate in phagolysosome, evades immune system
What are the three kinds of leishmania?
Cutaneous leishmaniasis (old world, new world), mucocutaneous leishmaniasis, visceral leishmaniasis
What causes mucocutaneous leishmaniasis?
metastasis of an untreated cutaneous leishmaniasis
What’s the worst kind of leishmania?
visceral leishmaniasis
What are symptoms of visceral leishmaniasis?
weight loss, enlarged spleen and liver, low blood counts
How do you definitively diagnose leishmaniasis?
microscopic detection in blood or tissue sample, serological tests for visceral leishmania
What are the treatments of leishmania?
Sodium stibogluconate, meglumine antimoniate, Miltefosine, Liposomal amphotericin B
What are the actions of sodium stibogluconate and meglumine antimoniate, what are they used for?
Leishmaniasis, organic antimonials
What is the mechanism of miltefosine? What’s it used for?
misunderstood mechanism; leishmaniasis?
What is the mechanism amphotericin B? What’s it used for?
Binds ergosterol to form pores in membranes; VISCERAL leishmaniasis
What does leishmaniasis look like under the microscope?
Depends on the life stage, but its intracellular when in the macrophages (looks like 2 dots for the HE stain)
What are the effects of a chronic Chagas’ disease infection?
cardiomyopathy, megacolonic segment, megaesophagus
What are the acute symptoms of Chagas’ disease
often asymptomatic, but can be mild typical immune response to infection
What causes Chagas’ disease?
T. cruzi
Where does T. cruz replicate?
intracellularly
How is Chagas’ disease (T. cruzi) definitively diagnosed?
ID of parasites in blood, chronic infection is usually diagnosed with more than one serological test
What is the treatment of Chagas’ disease (T. cruzi)
Nifurtimox and Benznidazole
What is the mechanisms of action for nifurtimox? What does it treat?
Induces oxidative stress due to inhibition of NAD(P)H-dependent dehydrogenases; Chagas’ disease (T. cruzi)
What is the mechanism of action for benznidazole?
Induces oxidative stress due to inhibition of NAD(P)H-dependent dehydrogenases; Chagas’ disease (T. cruzi)
What is required for nifurtimox and benznidazole to work?
Type-I nitroreductase to turn it from prodrug to active form
What does T. cruzi look like under the microscope
depends on what point it is in the life cycle; looks like T. brucei extracellularly, can be intracellular
What point in its life cycle does T. brucei infect humans at?
metacyclic trypomastigotes
What is a dead giveaway for T. brucei over T. cruzi
T. brucei reproduces asexually out of cells; they will be connected extracellularly
Where does T. brucei reproduce/live?
Extracellular. ALWAYS.
What two forms of T. brucei; where are they found?
T. brucei gambiense (West Africa, less severe), T. brucei rhodesiense (East Africa, acute)
What causes African sleeping sickness?
Trypanosoma brucei
What are side effects of African Sleeping sickness?
First stage: Chancre at bite site, fever, headache, swollen lymph nodes, muscle and joint aches.
Second stage: CNS development, somnolence (extreme sleepiness), altered gait, tremors, cranial neuropathies
What are the time scales for symptoms of T. brucei gambiense and rhodesiense?
Gambiense: CNS involvement after 1-2 years, death in 3 if not treated.
Rhodesiense: CNS involvement after a few weeks, death in months if untreated
What makes T. brucei gambiense so difficult to treat?
“Waves” of parasitemia where the parasite changes its active surface glycoproteins
What are treatments of African sleeping sickness?
Suramin, Pentamidine, Eflornithine, Melarsoprol
Whats the mechanism of action for suramin? What does it treat?
inhibits enzymes of pentose phosphate and glycolytic pathway; African sleeping sickness
What is the mechanism of action of pentamidine? What does it treat?
Interferes with DNA replication of mt genome; african sleeping sickness
What is the mechanism of action of eflornithine? What does it treat?
inhibits ornithine decarboxylase; african sleeping sickness
What is the mechanism of action of melarsoprol? What does it treat?
may relate to metabolism; african sleeping sickness
What does lymphatic filariasis cause?
elephantitis
What species causes lymphatic filariasis?
Wucheria bancrofti
What stage of Wucheria bancrofti is injected into humans?
L3 larvae
What stage of Wucheria bancrofti causes elephantitis?
Unsheathed microfilariae migrating to blood and lymph channels
What is the treatment of lymphatic filariasis?
Diethylcarbamazine
What is the mechanism of action of diethylcarbamazine? What does it treat?
arachidonic acid metabolic pathway of microfilariae; lymphatic filariasis
What causes toxoplasmosis?
Toxoplasma gondii
How is toxoplasmosis transmitted?
Via ingestion of oocyst from uncooked meat or cleaning a cat’s litter box
What are symptoms of toxoplasmosis?
In immunocompromised: fever, confusion, headaches, seizures, nausea, poor coordination
Ocular toxoplasmosis: red, painful photophobic eye
“headlight in the fog”
Can cause abnormal head size in fetus
Do you treat toxoplasmosis?
Not always, unless pregnant or immunocompromised
What are the treatments of toxoplasmosis?
Sulfadiazine and pyrimethamine, spiramycin in pregnant women, Atovaquone
