Parasites Flashcards
True or False: Toxoplasmosis in the immunocompetent host is usually a self-limited, mono-like illness.
True. There may be non-tender lymphadenophathy, night sweats, and atypical lymphs.
Regarding congenital toxoplasmosis, there are two important trends regarding gestational age and time of infection. Describe them.
- The LATER the gestation, the MORE likely to pass infection.
- 25% first trimester
- 54% second trimester
- 65% third trimester
- The EARLIER the gestation, the MORE SEVERE the consequences.
An infant was born with the following findings:
- Microcephaly
- Hydrocephalus
- Hepatosplenomegaly
- Maculopapular rash
- Chorioretinitis
- Cerebral calcifications disperesed through the brain parenchyma.
For how long must the child be treated? What are the drugs used? What two things must be monitored?
Since this is toxoplasmosis:
- 12 months of treatment
- Pyrimethamine, sulfadiazine, leucovorin
- Monitor:
- Eye exams at birth, 3, and 6 months
- CBC because of possible neutropenia
If present, chorioretinitis due to toxoplasma is treated with the typical 3-drug regimen as well as what additional drug?
- Leucovorin, pyramethamine, sulfdiazone.
- Steroids
What protozoan is associated with city-wide outbreaks due to contaminated municipal water sources? What treatment is used in immunocompetent hosts?
- Cryptosporidium
- None is needed.
- In others, nitaxozanide is the drug of choice.
You might also have thought of giardia but this tends to present as isolated cases from individuals or small groups sharing a contaminated water source.
Two conditions are especially at risk for cryptosporidium infection. What are they? What treatment can you give for these pateints during an outbreak?
- HIV and hyper-IgM syndrome
- Nitazoxanide
This organism is causing a watery diarrhea in an HIV-infected host.
- What is the organism?
- What is the treatment?
- Isospora belli
- It’s not cryptosporidium because those appear small and round whereas this organism is oval.
- Bactrim
An HIV-infected host presents with watery diarrhea. What would the shape of the organism be if he had:
- Cryptosporidium?
- Isospora belli?
- Giardia?
- Small, round
- Ovoid
- Kites with happy-faces. :)
In a small town, there is an outbreak of malaise, myalgia, low-grade fever, fatigue, and watery diarrhea. Several patients report eating raspberries from the grocery store which just received a new shipment from Nicaragua.
- What organism should you suspect?
- What is the treatment?
- Cyclospora
- Bactrim
Which malarial species is most associated with severe complications, including cerebral malaria, hypoglycemia, renal failure, respiratory failure, acidosis, anemia, and shock?
Plasmodium falciparum
(This is the one with “banana” gametocyte.)
True or False: This organism is associated with nephrotic syndrome.
FALSE: This is P. falciparum and although it is associated with renal FAILURE due to nephritis, but it is P. malariae that is most associated with nephrotic syndrome.
Which malarial species is most associated with chloroquine resistance?
P. flaciparum
A 16 year old returns from a visit to relatives in India and develops a febrile illness on return. Peripheral smear shows schizonts.
- Which malarial type is this NOT likey to be?
- What is the first line treatment?
- Not likely P falciparum because schizonts are not usually seen. (However, this is the one with banana gametocytes.)
- Usually can treat with chloroquine.
- P vivax has some resistance so Primaquine can be added.
For how long should chloroquine be taken before and after returning from a malaria-endemic area with minimal chloroquine resistance?
2 weeks before, 4-6 weeks after.
Before treating someone infected with malaria with primaquine, what must you screen for?
G6PD deficiency
What drug must be taken after chloroquine for successful treatment of P ovale and P vivax?
Primaquine
These are two different intracellular RBC parasites. Based on morphology, what are the likely organisms? What is the common vector for each?
- Babesia microti - Ixodes tick
- Plasmodium falciparum - Anopheles mosquito
A 9 year old with history of splenectomy due to prior history of trauma presents with high fever, hemolytic anemia, sweats, chills, and emotional lability. He had dental work before his trip to the Appalachian trail this summer. He has delayed immunization for meningococcus. He did have a tick bite and it was likely present > 2 days.
- What would you expect to see spirochetes on his peripheral smear?
- What factor in his history put him at higher risk for serious infection?
- What is the proper treatment?
Hemolytic anemia is the key here… with history of tick exposure, think of babesia infection.
- No, but you should see RBCs with maltese cross formations of parasites.
- Asplenia
- Two options:
- Atovaquone + azithro
- Clinda + quinine
You are seeing a 13 year old suspected of amebic liver abscess. Is it better to diagnose with this serology or abscess aspirate?
Serology, because the aspirate often shows no organisms.
In the US, what parasite is the most common cause of disease?
Giardia lamblia
What immune deficiency is commonly associated with Giardia infection?
IgA deficiency or hypogammaglobulinemia
List three drugs that can be used to treat giardia.
- Metronidazole
- Tinidazole
- Nitazoxanide
African sleeping sickness is caused by what organism? What is the vector?
- Trypanosoma brucei
- Tsetse fly
What are the causative organisms of sleeping sickness and Chagas disease? What are their geographic associations?
Both are caused by trypanosmites, but:
- Sleeping sickness = T. brucei, Africa
- Chagas = T. cruzi, Central/South America
This child has an infection cause by the bite of a “kissing bug.” He is from Costa Rica.
- What is the name of this physical exam finding?
- What are the cardiac complications that can develop after this infection?
- How do you treat this infection?
- Romaña sign
- Myocarditis, block, CHF
- Benznidazol and nifurtimox
A 13 year old from Bolivia has developed heart block, achalasia, megacolon, intermittent fever, lymphadenopathy, and malaise. He has Romaña sign. Which of the following drug(s) should be used to treat him?
- Metronidazole
- High-dose bactrim
- Benznidazole
- Clindamycin
- Atovaquone
- Chloroquine
- None: because this is yellow fever
- Nifurtimox
This is Chagas disease. Treat with two drugs:
- Benznidazole
- Nifurtimox
How do you treat giardia in a young child who cannot swallow pills?
Nitazoxanide which is available in suspension.
For each vector, state the parasitic infection most commonly associated.
- Sand fly
- Tsetse fly
- Tratomine insects (“kissing” bugs)
- Ixodes tick
- Anopheles mosquito
- Leishmaniasis
- African sleeping sickness… Trypanosoma brucei
- Chagas… Trypanosom cruzi
- Babesia microtii
- Malaria… P. falciparum, ovale, malariae, or vivax
A 7 year old from Brazil had a “cigarette paper” scar develop many weeks after a sand fly bite.
- What infection should you think about?
- What is the treatment?
- Leishmaniasis
- Ampho B
