Today, Ian Drobish presented not one but two cases of severe malaria this morning – the first was a case that he saw during his rotation in Kenya, and the second case was just recently admitted to the Hillcrest MICU after visiting relatives in Subsaharan Africa! Both patients presented with fever, nausea, vomiting, had traveled to high-transmission areas, and were found to be both anemic and thrombocytopenic. We took this opportunity to dive into the illness script for malaria, a disease we see rarely in the United States but one that causes significant morbidity and mortality in many other parts of the world.
First, we reviewed the epidemiology of malaria and identified malaria-endemic areas. Remember that malaria is caused by the female Anopheles mosquito and is therefore found in tropical areas. Transmission also varies by region, with Subsaharan Africa generally considered high transmission and Latin America and Asia are considered low transmission. In the United States, “VFR” (visiting friends and relatives) travelers such as our MICU patient are at highest risk for acquiring disease as they often return to their home country for longer duration and may not take prophylaxis due to presumed immunity.
We then discussed the pathophysiology of malaria, which is caused by the Plasmodium parasite. P. falciparum is responsible for the majority of malaria disease burden, and especially severe malaria cases due to its virulence factor pfEMP and ability to infect RBCs of any age. We followed the life cycle of the parasite, which starts with a mosquito bite (usually at night), travels to the liver in 1-2 hours, and then into the RBCs with ruptured schizonts causing symptoms 1-4 weeks after the initial bite.
Both of our patients met criteria for severe malaria, defined by any one of 12 WHO criteria which include organ failure, shock, and high parasitemia. Diagnosis was made with rapid antigen testing, and both thick and thin peripheral smear. Severe malaria can cause rapid deterioration with mortality rate highest in the first 24 hours of presentation and need IV artesunate with close monitoring.
For malaria patients in United States, providers must call the CDC malaria hotline to deliver this medication as it is not FDA approved or commercially available. Cinchona alkaloids (quinidine/quinine) were previously used, but have less efficacy and higher toxicity including QTc prolongation. Quinidine is also no longer stocked in US hospitals as of last year! Our MICU patient had her IV artesunate delivered from LAX, received 3 doses over 24 hours, and was discharged with oral artesunate after her peripheral smears showed parasitemia <1%. Both she and our patient in Kenya responded quickly to treatment and were discharged after 3 days.
Finally, our ID discussants Dr. Michael Tang, Dr. Thaidra Gaufin, and Dr. Samuel Penziner discussed malaria prophylaxis for travelers. Medication selection, which typically includes atovaquone-proguanil, mefloquine, or doxycycline, is dependent on resistance patterns of the region as well as co-morbidities. Thank you to our discussants (and Dr. Annie Cowell) for their insights, and to Ian Drobish for adding some global health learning to our morning reports!
Takeaway points:
- Any patient with a fever and recent travel to malaria-endemic region should be tested for malaria. “VFR” (visiting friends/relatives) travelers are at greatest risk.
- Use WHO criteria to determine severe malaria, which can lead to rapid deterioration and needs STAT treatment with IV artesunate.
- Call the CDC Malaria hotline to obtain IV artesunate, which is not commercially available in the United States. Quinidine is no longer stocked in the US, so use PO artesunate through an NGT while awaiting IV formulation.
https://www.cdc.gov/malaria/diagnosis_treatment/treatment.html
