Thread by @haematognomist

1/ Clinical #Pearls and summary of @NEJM #CPS:
"A Chilly Fever"
For full case: bit.ly/37Co43k

A young man presents in March w/ 1 week of fevers, shaking chills & severe headaches which peaked at night & defervescence by morning.

2/ My initial approach to fever is as follows, and is adapted from Penn frameworks: med.upenn.edu/frameworks/fev…

#PEARL1: I always try to remember the importance of assessing:
1. Host: immunosuppressed?
2. Exposures: work, sexual, travel, animals, IVDU, food/water

3/ He recently traveled to Cape Cod + trip to Uganda 2 years earlier w/ appropriate vaccinations and adherence to malaria ppx. This impacts the DDx:

⬆️ Tickborne infection:
- Lyme disease
- Anaplasmosis
- Babesiosis

#Medtwitter, which infections do you a/w travel to Uganda?

4/ Infections associated with travel to East Africa with long latency include:

• Malaria
• TB
• Filariasis (unlikely after short-term travel)
• Visceral leishmaniasis
• Q fever

The experts @CPSolvers have a phenomenal schema that applies here:
clinicalproblemsolving.com/%20dx-schema-f…

5/
Exam: splenomegaly
Labs: mild anemia, thrombocytopenia, elevated LDH to 283.
🚨 Peripheral blood smear demonstrates "intraerythrocytic parasites"🚨

What's the DDx for this finding & how can we use features of the smear to help narrow the DDx?

6/ Major DDx in this case is babesia vs. malaria

#PEARL2:
"Intracellular vacuoles and extracellular merozoites = unusual in malaria but common in babesiosis. Maltese cross (a tetrad of parasites budding at right angles) is unique to babesia. 👇🏾
bit.ly/2sQipb5

7/ #PEARL3, smear in malaria:

"Plasmodia metabolize heme to form an intracellular crystallized pigment, hemozoin. Although hemozoin is not invariably identified in cases of malaria, its presence reliably distinguishes malaria infection from babesia"

In this patient. Final dx...

8/
Given Schüffner's dots + more mature ameboid trophozoites + pigment-containing, rounded gametocytes:

Consistent with 🌟P. vivax🌟

Malaria life cycle is complicated! CDC graphic below:
bit.ly/39GHgyw

9/ #PEARL4:

"Chloroquine should effectively end this relapse by eliminating parasitemia, it will not prevent future relapses, since it does not affect the latent forms of P. vivax (hypnozoites) in the liver. A 2wk course of primaquine can clear the hepatic reservoir of malaria"

10/ Summary:
🔥Fever DDx is broad - try to have an organized approach!

🕷️🩸 Travel history pointed in direction of tickborne & parasitic dz

💊 Chloroquine doesn't effectively treat hypnozoites, whereas primaquine does!

Tagging @TxID_Edu for inspiration and additional thoughts!

@TxID_Edu ❗️BONUS:
Here's a google sheet with links to all clinical pearls from:
> 60 Clinical Problem Solving Cases
> 260 Case Records of MGH

Compiled over the course of my med school career.
Cheers! 🍾
tinyurl.com/dailypearls