Malaria Flashcards
What is Malaria?
a potentially life‑threatening tropical infectious disease caused by Plasmodium parasites, which are transmitted through the bite of an infected female Anopheles mosquito
Epidemiology of Malaria?
- Most cases of malaria occur in tropical Africa (West and Central Africa).
- Transmission also occurs in other tropical and subtropical regions such as South and Southeast Asia, and Central and South America
Incubation period of malaria?
7-30 days
- The incubation period of malaria is a minimum of seven days; if fever occurs before the seventh day following exposure in an endemic region, it is most likely not due to malaria.
Symptoms of malaria?
nonspecific symptoms like fever, nausea, and vomiting
Gold standard for diagnosing malaria?
- identification of parasites in RBCs on a blood smear
- although rapid diagnostic tests to identify Plasmodium antigens are used with increasing frequency
Classification of malaria?
- severe
- uncomplicated
Signs of severe malaria?
characterized by severe organ dysfunction
Treatment of severe malaria?
affected individuals should be admitted to the ICU and receive IV antimalarials immediately
Treatment for uncomplicated malaria?
treated with oral antimalarials
Pathogen that causes malaria?
plasmodia
- eukaryotic parasite belonging to the sporoza group
Name the different types of plasmodia?
- plasmodium falciparum - most virulent
- plasmodium vivax
- plasmodium ovale
- plasmodium knowlesi
- plasmodium malariae
Malaria vector?
the female anopheles mosquito
What conditions offer partial resistance against malaria?
- carriers of sickle cell mutation
- Other hemoglobinopathies (e.g., thalassemia, HbC)
- Infection with malaria subsequently leads to the development of specific Plasmodium antibodies that result in partial immunity for a limited amount of time (less than a year)
Pathophysiology - asexual development in humans?
- Transmission of Plasmodium sporozoites via Anopheles mosquito bite → sporozoites travel through the bloodstream to the liver of the host
- Liver: sporozoites enter hepatocytes → sporozoites multiply asexually → schizonts are formed containing thousands of merozoites → release of merozoites into the bloodstream
- Circulatory system: Merozoites enter erythrocytes → maturation to trophozoites → red cell schizonts are formed containing thousands of merozoites → release of merozoites into the bloodstream (which causes fever and other manifestations of malaria) → penetration of erythrocytes recurs
- Merozoites enter erythrocytes → differentiation into gametocytes (male or female)
- Gametocytes mature into oocysts in the mosquito → mature into sporozoites
Pathophysiology - sexual development in female Anopheles mosquito?
A mosquito bites an infected human and ingests gametocytes → gametocytes mature within the mosquito intestines → sporozoites are formed and these migrate to the salivary glands → transmission of sporozoites to humans via mosquito bite
Describe the course of the malaria illness?
Infection → asymptomatic parasitemia → uncomplicated illness → severe malaria → death
General malaria symptoms?
- Flu‑like symptoms, headache
- Diaphoresis
- High fever
Blood specific symptoms of malaria?
- Thrombocytopenia: increased bleeding risk
- DIC might occur in severe cases - Hemolytic anemia: weakness, paleness, dizziness
Gastrointestinal specific symptoms of malaria?
Nausea, vomiting
Diarrhea, abdominal pain
Liver specific symptoms of malaria?
- hepatosplenomegaly
- discrete jaundice
CNS specific symptoms of malaria?
- hallucinations
- confusion
- impaired consciousness
- seizures
- coma
Diagnostic approach to malaria?
- Focused clinical evaluation
- Time of travel to regions where malaria is endemic and previous chemoprophylaxis
- Evaluate for signs of severe malaria. - Routine laboratory studies
- CBC, CMP, LFTs, and coagulation panel to evaluate for organ dysfunction - Parasitological testing
- confirms the presence and determines the species of Plasmodia e.g. MRDT, thick and thin blood smears
What are the routine lab studies done in malaria?
- FBC
- CMP/Urea and electrolytes
- Urinalysis
CBC of a malaria patient?
- Hemolytic anemia
- ↓ Hb, ↓ haptoglobin, ↑ LDH, ↑ indirect bilirubin, ↑ reticulocytes - Thrombocytopenia
Leukocytosis or leukopenia are uncommon except in severe disease
CMP/Urea and electrolytes of a malaria patient?
hypoglycemia can occur in severe malaria
Urinalysis of a malaria patient?
hemoglobinuria may occur with intravascular hemolysis
What is a MRDT?
- Detects specific malaria antigens
- Allows for quick diagnosis if high‑quality microscopy is unavailable or delayed
What is a blood smear in malaria testing?
allows for visualization of parasites within RBCs via microscopy to confirm malaria diagnosis
Why is a blood smear good in malaria testing?
- Allows identification of Plasmodium species
- Enables calculation of malaria parasitemia: the percentage of RBCs containing a Plasmodium organism; used to classify severity and monitor response to therapy
What is found on a blood smear in malaria testing?
- Schuffner granules (fine, brick-red dots) within RBCs infected with P. vivax and P. ovale
- Crescent-shaped gametocytes in individuals infected with P. falciparum
Classification of malaria?
- uncomplicated malaria
- severe malaria
Describe uncomplicated malaria?
Definition: symptomatic, diagnostically proven malaria without features of severe malaria
Etiology: can be caused by all Plasmodium species
Describe severe malaria?
Description: potentially fatal manifestation or complication of malaria
Etiology: most commonly a result of falciparum malaria
Pathophysiology: Infected erythrocytes occlude capillaries, which can lead to severe organ dysfunction.
Criteria for severe malaria?
≥ 1 of the following in a patient with proven malaria:
1. General: prostration
2. CNS: hallucinations, confusion, impaired consciousness, seizures, coma
3. Cardiac: shock (e.g., hypotension, capillary refill time ≥ 3 seconds), heart failure
4. Pulmonary: respiratory distress, pulmonary edema, ARDS
5. Renal: flank pain, oliguria, hemoglobinuria, acute kidney injury
6. Gastrointestinal: jaundice
7. Hematopoietic: significant bleeding
Lab findings in severe malaria?
Severe anemia: < 7 g/dL in adults, < 5 g/dL in children
Hypoglycemia: < 40 mg/dL
Acidosis (with or without lactemia): base deficit > 8 meq/L or bicarbonate < 15 meq/L
Hyperlactatemia: lactate > 5 meq/L
Acute kidney injury: creatinine > 3 mg/dL or urea > 20 mmol/L
Hyperbilirubinemia: bilirubin > 3 mg/dL
High malaria parasitemia
Treatment for severe malaria?
Start IV artesunate
Treatment for uncomplicated malaria?
lumefantrine-artemethar - LA
