Fast Five Quiz: Mosquito-Borne Diseases

Michael Stuart Bronze, MD


May 06, 2020

Malaria is a potentially life-threatening disease caused by infection with Plasmodium protozoa transmitted by an infective female Anopheles mosquito. Plasmodium falciparum infection carries a poor prognosis with a high mortality if untreated, but it has an excellent prognosis if diagnosed early and treated appropriately.

Patients with malaria typically become symptomatic a few weeks after infection, although the host's previous exposure or immunity to malaria affects the symptomatology and incubation period. In addition, each Plasmodium species has a typical incubation period. Of note, virtually all patients with malaria present with headache. Clinical symptoms also include:

  • Cough

  • Fatigue

  • Malaise

  • Shaking chills

  • Arthralgia

  • Myalgia

  • Paroxysm of fever, shaking chills, and sweats (every 48 or 72 hours, depending on species)

Less common malarial symptoms include:

  • Anorexia and lethargy

  • Nausea and vomiting

  • Diarrhea

  • Jaundice

The classic paroxysm begins with a period of shivering and chills which lasts for approximately 1-2 hours and is followed by a high fever. Finally, the patient experiences excessive diaphoresis, and the body temperature of the patient drops to normal or below normal.

In returning travelers from endemic areas, malaria is suggested by the triad of thrombocytopenia, elevated LDH levels, and atypical lymphocytes. These findings should prompt obtaining malarial smears.

Despite the activity of artemisinin and its derivatives, monotherapy with these agents has been associated with high rates of relapse. This may be due to the temporary arrest of the growth of ring-stage parasites (dormancy) after exposure to artemisinin drugs. For this reason, monotherapy with artemisinin drugs is not recommended.

According to guidelines from the World Health Organization (WHO), children and adults with severe malaria should be treated with intravenous or intramuscular artesunate for at least 24 hours and until they can tolerate oral medication. This includes infants, pregnant women in all trimesters, and lactating women. Once patients have received at least 24 hours of parenteral therapy and can tolerate oral therapy, they should complete treatment with 3 days of artemisinin-based combination therapy (ACT).

Read more about malaria.


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