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Old 03-25-2011
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RBC Ring-like and Crescent-like forms in RBC

A woman, recently returned from Africa, complains of having paroxysmal attacks of chills, fever, and sweating; these attacks last a day or two at a time and recur every 36 to 48 h. Examination of a stained blood specimen reveals ringlike and crescent-like forms within red blood cells. The infecting organism most likely is

a. Plasmodium falciparum
b. Plasmodium vivax
c. Trypanosoma gambiense
d. Wuchereria bancrofti
e. Schistosoma mansoni

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Old 03-25-2011
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Ring-like form inside RBC is the buzz word for Plasmodium falciparum infection.

The answer is : A
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Answer is B Plasmodium vivax:

Paroxysmal attacks of chills, fever, and sweating; these attacks last a day or two at a time and recur every 36 to 48 h.

Plasmodium falciparum, the episodes of fever and chills are continuous...
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Quote:
Originally Posted by luisguaman View Post
Answer is B Plasmodium vivax:

Paroxysmal attacks of chills, fever, and sweating; these attacks last a day or two at a time and recur every 36 to 48 h.

Plasmodium falciparum, the episodes of fever and chills are continuous...
Fever in Plasmodium falciparum infection is initially continuous and tend to be irregular but along the time it might resemble the fever patern of P. ovale and vivax which recur every 36-48 h. Another important clue in the question stem is the presence of ring like trophozoites and crescent /banana shaped gametes which are charactericstics of P. falciparum
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the answer is A..
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Quote:
Originally Posted by harlesmd View Post
Fever in Plasmodium falciparum infection is initially continuous and tend to be irregular but along the time it might resemble the fever patern of P. ovale and vivax which recur every 36-48 h. Another important clue in the question stem is the presence of ring like trophozoites and crescent /banana shaped gametes which are charactericstics of P. falciparum
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Originally Posted by luisguaman View Post
Answer is B Plasmodium vivax:

Paroxysmal attacks of chills, fever, and sweating; these attacks last a day or two at a time and recur every 36 to 48 h.

Plasmodium falciparum, the episodes of fever and chills are continuous...
Fevers indicate hemolysis, which is never continuous. (I've gotten malaria to confirm this hehe)

Most characteristic feature is timing and appearance of RBC.

P. Falciparum is 24 - 36 hrs + ring like trophozoites
P. Vivax (tertian fever ) - Every 3 days.. so 48 Hrs..
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Old 03-26-2011
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Another potential question that can be asked:

A patient presents with intermittent fevers and chills along with fatigue and pallor. Blood smear shows ring forms in red blood cells. Patient recently returned from a camping trip on the east coast. Which of the following organisms is most likely the cause of the patient's fever?

A. Borrelia burgdorferi
B. Plasmodium falciparum
C. Plasmodium vivax
D. Babesia microti
E. Trypanasoma gambiense

Bonus: What is the treatment?

**Tough question
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Nice! Babesia -> azithromycin and atovaquone.

And maybe doxycycline for empirical tx of lyme disease?
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Quote:
Originally Posted by Mondoshawan View Post
Nice! Babesia -> azithromycin and atovaquone.

And maybe doxycycline for empirical tx of lyme disease?
You are very intelligent my friend. Both treatments are correct. I'm not sure if you would give rx for both babesiosis and lyme. I would def give both if there were signs of Lyme disease infection such as bilateral facial palsy or arthralgias. Empiric rx is prob outside the scope of step 1, but you are already thinkin like a experienced doc!
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