Malaria
Content
BAS 9/16/02
Malaria
Key Points:
• For a traveler with a fever, you MUST think of 4 diseases: malaria, typhoid, dengue, and TB.
• Malaria presents with episodic fevers, sweats, headache, myalgias, abdominal pain, etc. weeks to
years after initial exposure.
• Patients can have hemolysis, thrombocytopenia, elevated LFTs. Diagnosis is by thick or thin
smear.
Definition
• Human malaria is caused by four species of the parasite Plasmodia: P. falciparum, P. vivax, P.
ovale, and P. malariae
Epidemiology
• Malaria transmission occurs via the bite of a female Anopheles sp. mosquito
• The life cycle involves an initial liver phase, followed by invasion of red blood cells
• All four species live within red blood cells and digest their proteins and hemoglobin
• A number of hemaglobinopathies appear to protect against malaria including sickle cell and
alpha and beta-thallassemia
Clinical Presentation
• Patients are asymptomatic after the initial bite until the erythrocytic phase
• Acute symptoms of malaria are the same for all 4 species:
! Fever is very common and comes from rupture of merozoites from red blood cells
o Classically, every other day (every 48 hrs)
! Other common symptoms: sweats, headache, myalgias, fatigue, abdominal pain,
diarrhea, cough
! Exam: Can see anemia, splenomegaly, hepatomegaly, and jaundice
! Labs: anemia, hemolysis, thrombocytopenia, elevated LFTs, high bilirubin
• P. vivax and P. ovale:
! Can see hemolysis but the disease is usually mild (low parasitemia)
! Both have dormant liver forms and late relapses of both can occur
• P. malariae
! Typically a low grade infection with mild symptoms which can persist for greater
than 40 years
• P. falciparum
! Causes the most severe disease – infects RBC’s of all ages
! High-risk patients include: immunocompromised, pregnant, kids < 5, asplenic
! Complications include cerebral malaria, renal failure, pulmonary edema/ARDS,
anemia and bleeding, hypoglycemia
Diagnosis
• Standard is light microscopy of a thick and/or thin blood smear
• Because of the cyclical nature of the parasitemia, smears should be done every 6-12 hours for
48 hours (but, first smear is positive in 95% of cases)
Treatment
• Chloroquine for chloroquine-sensitive P. vivax, P. ovale, and P. malariae
! Treatment is 3 days
• Quinine (or meflequine, atovaquone) for chloroquine-resistant strains and all P. falciparum
infections
• P. vivax and P. ovale also need to be treated with two weeks of primaquine to prevent the
dormant liver phase
Malaria
Key Points:
• For a traveler with a fever, you MUST think of 4 diseases: malaria, typhoid, dengue, and TB.
• Malaria presents with episodic fevers, sweats, headache, myalgias, abdominal pain, etc. weeks to
years after initial exposure.
• Patients can have hemolysis, thrombocytopenia, elevated LFTs. Diagnosis is by thick or thin
smear.
Definition
• Human malaria is caused by four species of the parasite Plasmodia: P. falciparum, P. vivax, P.
ovale, and P. malariae
Epidemiology
• Malaria transmission occurs via the bite of a female Anopheles sp. mosquito
• The life cycle involves an initial liver phase, followed by invasion of red blood cells
• All four species live within red blood cells and digest their proteins and hemoglobin
• A number of hemaglobinopathies appear to protect against malaria including sickle cell and
alpha and beta-thallassemia
Clinical Presentation
• Patients are asymptomatic after the initial bite until the erythrocytic phase
• Acute symptoms of malaria are the same for all 4 species:
! Fever is very common and comes from rupture of merozoites from red blood cells
o Classically, every other day (every 48 hrs)
! Other common symptoms: sweats, headache, myalgias, fatigue, abdominal pain,
diarrhea, cough
! Exam: Can see anemia, splenomegaly, hepatomegaly, and jaundice
! Labs: anemia, hemolysis, thrombocytopenia, elevated LFTs, high bilirubin
• P. vivax and P. ovale:
! Can see hemolysis but the disease is usually mild (low parasitemia)
! Both have dormant liver forms and late relapses of both can occur
• P. malariae
! Typically a low grade infection with mild symptoms which can persist for greater
than 40 years
• P. falciparum
! Causes the most severe disease – infects RBC’s of all ages
! High-risk patients include: immunocompromised, pregnant, kids < 5, asplenic
! Complications include cerebral malaria, renal failure, pulmonary edema/ARDS,
anemia and bleeding, hypoglycemia
Diagnosis
• Standard is light microscopy of a thick and/or thin blood smear
• Because of the cyclical nature of the parasitemia, smears should be done every 6-12 hours for
48 hours (but, first smear is positive in 95% of cases)
Treatment
• Chloroquine for chloroquine-sensitive P. vivax, P. ovale, and P. malariae
! Treatment is 3 days
• Quinine (or meflequine, atovaquone) for chloroquine-resistant strains and all P. falciparum
infections
• P. vivax and P. ovale also need to be treated with two weeks of primaquine to prevent the
dormant liver phase
