Intro to Parasitic Infections Flashcards

Question

Acute Chagas

Answer 1

symptoms are often asymptomatic but often mild, typical innate immune response to an infection. Often acquired early in life. Occasionally severe. Without treatment at the acute stage, individuals do not entirely clear the parasite, go on to the chronic stage.

Answer 2

T. cruzi replicates intracellularly (immune evasion), but does exit cell in an additional life stage to find a new cell. The presence of parasites and a continuous low-grade immune response (inflammatory) is what is thought to contribute to the following: Myocarditis Megaesophagus Megacolon Also, symptoms can reappear in chronic indeterminate individuals if they become immunocompromised

Answer 3

Identification of parasites in blood (acute or recurring infection only). Chronic infection is usually diagnosed with more than one serological test.

Answer 4

Yes! Drugs are effective in acute stages, use and effectiveness in chronic stages where cardiomyopathy has developed is controversial. Permanent damage.

Answer 5

nitroaromatics: Nifurtimox & Benznidazole are well absorbed from GI tract, no IV administration necessary. Nifurtimox induces oxidative stress due to inhibition by NAD(P)H-dependent dehydrogenases with subsequent impairment of mitochondria membrane potential, Benznidazole has similar mechanism

Answer 6

``` Chagas disease (T. cruzi) well absorbed from GI tract, no IV administration necessary. Nifurtimox induces oxidative stress due to inhibition by NAD(P)H-dependent dehydrogenases with subsequent impairment of mitochondria membrane potential, Benznidazole has similar mechanism ```

Answer 7

This drug class requires a bacterial-like Type I nitroreductase to turn it from a prodrug to the active form. Trypanosomes have one, typical eukaryotic cells do not.

Answer 8

Trypanosoma brucei | ALWAYS EXTRACELLULAR

Answer 9

1. Tsetse fly takes blood meal - injects metacyclic trypomastigotes --> injected metacyclic trypomastigotes transform into blood stream trypomastigotes which are carried to other sites --> multiply by binary fission in various body fluids --> trypomastigotes in blood taked up by tsetse fly again --> transform into procyclic trypomastigotes in midgut - multiply --> leave midgut and transform into epimastigotes - multiply in salivary gland = metacyclic trypomastigotes

Answer 10

Trypanosoma brucei gambiense, West Africa Less severe, longer lasting African Sleeping Sickness Trypanosoma brucei rhodesiense, East Africa More acute illness

Answer 11

First stage: possible chancre at site of bite, fever, headache, swollen lymph nodes, muscle and joint aches, possibly rash or itchiness

Answer 12

Second stage: CNS involvement, neurological symptoms include Somnolence (extreme sleepiness, esp. at inappropriate times), altered gait, tremors, cranial neuropathies, urinary incontinence, personality changes

Answer 13

gambiense: CNS involvement after 1-2 yrs, death usually in 3 if not treated rhodesiense: CNS involvement after a few weeks, death in a few months if not treated

Answer 14

“Waves” of parasitemia are a major challenge to the immune system. Not intracellular so immune system should find - organisms switch surface proteins/antigens to proliferate and evade immune system

Answer 15

Positive diagnosis is finding organisms in blood (special labs do this test), and in CSF if in second stage

Answer 16

YES | The earlier the better! Sleeping sickness is Invariably fatal unless treated (waves of parasitemia)

Answer 17

No vaccine or preventative is available

Answer 18

Suramin: Has an inhibitory effect on enzymes of the pentose phosphate and glycolytic pathways. Selectively accumulates in trypanosomes. Pentamidine: Possible mechanism: interference with DNA replication of its unique mitochondrial genome. Selectively accumulates in trypanosomes. Eflornithine: inhibits ornithine decarboxylase, which turns over faster in human cells than in trypanosomes Melarsoprol: Unknown mechanism, may relate to metabolism

Answer 19

Has good absorption from GI tract (other don't - give IV) but can't cross BBB to CSF (co-treat with eflornithine)

Answer 20

tissue nematode Wuchereria bancrofti | transmitted by female mosquito

Answer 21

Mosquito takes blood meal - L3 larvae enter skin --> adults into lymphatics - sexually reproduce to produce sheathed microfilaraie that migrate into lymph and blood channels --> mosquito takes blood meal and microfilariae --> shed sheaths, penetrate mosquito's midgut and migrate to thoracic muscles --> L1 larvae --> L3 larvae --> migrate to head and proboscis

Answer 22

Endemic to tropical areas in Asia, Africa, the Western Pacific, and parts of the Caribbean and South America.

Answer 23

Larvae enters skin and gains access to the lymphatic system where it matures to adult worms. The adult worms only live in the human lymph system

Answer 24

lymphedema and elephantiasis and in men, swelling of the scrotum, called hydrocele. Lymphatic filariasis is a leading cause of permanent disability worldwide. Most individuals infected never develop clinical symptoms, or if they do, these symptoms appear years after initial infection. However, it may impact functioning of the lymphatic system, which in turn means the individual cannot fight bacterial infections as effectively.

Answer 25

most typical is blood smear. Microfilariae that cause lymphatic filariasis circulate in the blood at night. Blood collection should be done at night to coincide with the appearance of the microfilariae. Alternately, elevated levels of antifilarial IgG4 in the blood can be detected with a serological assay.

Answer 26

No vaccines or preventatives, but MDA have been successful at wiping out the disease in certain foci, also important is mosquito control.

Answer 27

Depends on whether infection in active or not Lymphedema and elephantiasis are not indications for DEC treatment because most people with lymphedema are not actively infected with the filarial parasite. Hygiene assistance suggested. The treatment for hydrocele is surgery

Answer 28

Diethylcarbamazine (DEC) administered orally, kills microfilaria and some adult worms. No longer FDA approved. Mechanism of action is on the arachidonic acid metabolic pathway in microfilaria. Generally well tolerated; however, DEC should not be administered to patients who may also have onchocerciasis as DEC can worsen onchocercal eye disease. In patients with loiasis, DEC can cause serious adverse reactions, including encephalopathy and death. Doxycycline????

Answer 29

Caused by Toxoplasma gondii parasite

Answer 30

ingested as a tissue cyst (uncooked meat) or an Oocycst from unwashed produce or cat feces. Also, in its life cycle, it forms muscle tissue cysts in its non-definitive hosts, which is one of the ways it is transmitted to humans.

Answer 31

neurotropic | muscle and brain cells

Answer 32

``` Immunocompromised- cerebral abscesses, fever, confusion, HA, seizures, nausea, poor coordination Ocular toxoplasmosis (headlight in fog lesion) ``` A fetus if the mother is first infected during that pregnancy --> Stillbirth or miscarriage Abnormal head size (small or large) May seem normal at birth but later develop: vision loss, mental disability, and seizures The earlier in pregnancy the infection occurs, the more severe the symptoms

Answer 33

most common: red, painful, photophobic eye, with some decrease in visual acuity."headlight in the fog" lesion with multiple surrounding healed chorioretinal scars in one eye (need not be immunocompromised to get ocular toxoplasmosis, but more likely)

Answer 34

Serological testing is possible, but diagnosis requires some estimate of time of infection

Answer 35

Vaccines are not available

Answer 36

Not for most patients. Most will recover w/out tx, asymptomatic anyway Pregnant women, newborns, and infants will need to be treated but note the caveats Patients with ocular toxoplasmosis if the size, location, or characteristics of the lesion (actively growing) warrant it should be treated The immunocompromised should be treated, until they have improvements in their condition AIDS patients may require lifelong treatment as long as they remain immunosuppressed

Answer 37

Toxoplasma, babesia, malaria

Answer 38

Some antimalarial combos also work on Toxoplasma and Babesia (apicomplexans) High concentration in tissues over long times is desired - Atovaquone Folate antagonist combo**** Sulfadiazine (Fundamentals) and Pyrimethamine (anti-malarial) Folinic acid often co-administered Specificity…T. gondii cannot utilize presynthesized folinic acid Pregnant women shouldn’t use these drugs unless extreme circumstances warrant its use, instead, the experimental spiramycin could be obtained from the FDA. Does not cross placenta. A macrolide - prevent peptidyltransferase from adding the growing peptide attached to tRNA to the next amino acid, inhibiting ribosomal translation, premature dissociation of the peptidyl-tRNA from the ribosome.

Answer 39

- inhibitory effect on enzymes of PPP and Glycolytic pathways, trypanosomes (ASS)

Answer 40

- interference w/ DNA replicatoin of unique mitochondrial genome (ASS)

Answer 41

- inhibits ornithine decarboxylase, which turns over faster in human cells than trypanosomes (ASS)

Answer 42

- unknown MOA (ASS)

Answer 43

T. brucei Enters into bloodstream Bloodstream CNS

Answer 44

T. cruzi Enters mucosal tissue/dermal cells bloodstream, cardiac, GI

Answer 45

Leishmania spp Enters via skin macrophage Skin, systemic

Answer 46

Toxoplasma gondii Enters via GI tract GI, brain tissue, fetus, eyes

Answer 47

Onchocerca volvulus Enters via SubQ Skin and Eyes

Answer 48

Wucheria bancrofti Enters via skin Lymphatic tissue