What are the symptoms and treatment of malaria?

Symptoms of Malaria

Malaria typically presents with non-specific flu-like symptoms including fever, headache, chills, myalgia (muscle aches), malaise, and may include vomiting, diarrhea, and cough. 1, 2

Clinical Presentation

Early Symptoms

• Fever is the hallmark symptom, though approximately half of patients may be afebrile at initial presentation despite having a history of fever 1
• Headache, chills, and body aches occur commonly alongside fever 3, 4
• Gastrointestinal symptoms including vomiting (10-12%), diarrhea (8%), abdominal pain (17%), and anorexia (5%) are frequent 1, 5
• Respiratory symptoms such as cough may occur 1
• General malaise and weakness (asthenia) affect approximately 8% of patients 5

Physical Examination Findings

• Splenomegaly may be present but is often absent in early disease 1
• Jaundice can occur, particularly in more advanced cases 1
• No specific fever pattern exists in most cases, contrary to classic teaching 1

Laboratory Abnormalities

• Thrombocytopenia occurs in 70-79% of cases and has a positive likelihood ratio of 5.6-11.0 for malaria diagnosis 6
• Anemia develops as the disease progresses 1
• Hyperbilirubinemia has a likelihood ratio of 7.3 for malaria 6

Timing and Incubation

Symptoms typically begin 10 days to 4 weeks after mosquito transmission, though presentation can occur as early as 8 days or as late as one year, particularly with P. vivax, P. ovale, or P. malariae infections or in patients who took prophylaxis 1, 2

• Most patients (92.6%) develop symptoms within 90 days of returning from malarious areas 7
• P. falciparum typically presents within 1 month of return but may present up to 6 months later 1
• P. vivax and P. ovale can present up to a year or longer due to dormant liver stages 1

Severe Malaria Warning Signs

Severe malaria constitutes a medical emergency and includes any of the following features 1, 2:

Neurological Complications

• Depressed conscious level (any degree) 1
• Active seizure activity 1
• Confusion or reduced Glasgow coma scale may indicate cerebral malaria 1

Respiratory Complications

• Hypoxia (oxygen saturations <95%) 1
• Irregular respirations or obstructed airway 1
• Tachypnea and signs of pulmonary edema 1

Cardiovascular Complications

• Shock (systolic blood pressure <80 mm Hg or <70 mm Hg if aged <1 year) 1
• Tachycardia, cool peripheries, capillary refill time ≥3 seconds 1

Metabolic Complications

• Hypoglycemia (<3 mmol/L) 1
• Metabolic acidosis (base deficit >8 mmol/L) 1
• Kidney failure may develop 1

Hematologic Complications

• Severe anemia (hemoglobin <100 g/L) 1
• Hyperparasitemia (>5%) 1

Critical Clinical Context

Malaria should be considered in ANY patient with fever who has EVER traveled to a malaria-endemic area, as delayed diagnosis is associated with increased mortality 1, 6

• The illness begins with non-specific symptoms that can easily be mistaken for influenza or other viral illnesses 1, 2
• Failure to expedite appropriate referral may lead to life-threatening disease 1
• Early diagnosis and appropriate treatment significantly improve outcomes 2

Common Pitfall to Avoid

Do not dismiss malaria based on absence of fever at presentation—almost all patients have a history of fever even if afebrile when examined, and roughly half are afebrile on initial presentation 1. The non-specific nature of early symptoms means malaria can be easily overlooked, which is responsible for preventable deaths every year in non-endemic settings 2.