Malaria is potentially fatal condition caused by infection of red blood cells with parasites. Malaria is transmitted to humans by the bite of an infected Anopheles mosquito. If an individual is bitten, the clinical outcome may be (1) no infection, (2) asymptomatic infection, where the parasite is present in blood, but they remain symptom free, (3) uncomplicated malaria, where the patient has symptoms, but no systemic organ dysfunction. Lastly, (4) severe malaria, where symptoms coincide with major organ dysfunction. Outside of being bitten, other modes of transmission include congenital infection and transmission by blood transfusion, organ transplantation, or sharing of dirty needles, but malaria acquired by these routes and local mosquito-transmitted malaria occur very infrequently in the U.S.
In the United States approximately 1700 cases of malaria are diagnosed annually, with a majority of cases associated with overseas travel to a malaria-endemic country. The majority of deaths occur in Africa (91%), Southeast Asia (6%), and the Eastern Mediterranean region (2%), the remaining 1% is scattered across various other regions.
The clinical symptoms of malaria are variable and can include fever (they may come and go in a somewhat predictable fashion), chills, rigor, sweating, headache, muscle pain, nausea, and diarrhea. In severe malaria, jaundice, splenomegaly, hepatomegaly, shock, bleeding, seizures or coma may occur. In patients with chronic malaria or with repeated infections the spleen may be massively enlarged. If you have traveled abroad - don't minimize these symptoms as "just the flu".
Below is a peripheral blood sample smeared onto a slide and magnified 100x under a microscope, notice the ring forms that are inside select red blood cells. This is a classic presentation of a pretty bad "heavy" infection/disease burden.
The patient's clinical outcomes are dependent on several factors as well. Parasite factors include: the species, multiplication rate, virulence, and drug resistance. Host factors are centered around age, pregnancy status, immune status, previous exposure, coinfection with other pathogens. Geographic and social factors can include: endemicity, poverty, availability of prompt and effective treatment. Even with treatment, in cases of severe malaria, the mortality rates can approach 20%.
The good news is that for most patients who are caught early in the disease process, Malaria is a treatable disease. Newer drugs like Artemisinin-based combination therapies (ACTs) are the most effective antimalarial medicines available today and the mainstay of recommended treatment for Plasmodium falciparum malaria, the deadliest malaria parasite globally.
ACTs combine 2 active pharmaceuticals with different mechanisms of action, including derivates of artemisinin extracted from the plant Artemisia annua and a partner drug. The role of the artemisinin compound is to reduce the number of parasites during the first 3 days of treatment, while the role of the partner drug is to eliminate the remaining parasites.
Even today the World Health Organization (WHO) is coordinating a major global effort to control and eliminate malaria. These efforts include implementation of indoor chemical spraying, distribution of millions of insecticide-treated sleeping nets in high-risk areas, and promotion of policies for appropriate treatment in regions of endemic disease. Further research and testing also continues in the area of a successful vaccine.
November 4, 2024
Author: Joshua Ishmael, MBA, MLS(ASCP)CM, NRP
Pass with PASS, LLC
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