Diagnostic criteria
2.1 Asymptomatic carrier
Asymptomatic carrier can be diagnosed if the following conditions are met.
2.1.1 Clinical symptoms: the patient had no clinical symptoms of malaria, such as no obvious fever, chills, sweating or no typical periodic attacks.
2.1.2 Parasitological test: Plasmodium spp. can be found in blood smears under a microscopy, or, a rapid diagnosis test (RDT) for Plasmodium spp. antigen, is positive, or a nucleic acid test for Plasmodium spp. is positive.
2.2 Clinically diagnosed cases
Those who meet one of the following conditions (1) or (2) can be diagnosed as clinically diagnosed cases.
(1) The patients have both epidemiological history and typical clinical symptoms of malaria.
① Epidemiological history: they had stayed in malaria endemic areas during the malaria transmission season, stayed over night, or had a history of blood transfusion in the past two weeks.
② Clinical symptoms: typical symptoms characterized by periodic attacks, once every day, every other day or every two days, or malaria symptoms such as chills, fever, sweating, or splenomegaly and anemia after multiple episodes of cold and fever.
(2) The patients have a history of epidemiology and atypical clinical symptoms of malaria at the same time.
① Epidemiology history: the patients had stayed in the malaria endemic area during the malaria transmission season, stayed over night or had a history of blood transfusion in the past two weeks.
② Clinical symptoms: atypical with chills, fever, sweating and other symptoms. However, the fever type and attack are irregular.
2.3 Confirmed cases
On the basis of clinical diagnosis, a confirmed case can be diagnosed as long as there is one positive result of parasitological tests. In other words, malaria parasite can be detected in blood smear under a microscopy, or a malaria RDT is positive, or a malaria parasite nucleic acid test is positive.
Those who meet one of the following conditions can be diagnosed as confirmed cases.
① The patient has epidemiological history and typical or atypical clinical symptoms of malaria. Plasmodium spp. can be found in blood smear under a microscopy at the same time.
② The patient has epidemiological history and typical or atypical clinical symptoms of malaria. RDT for malaria is positive at the same time.
③ The patient has epidemiological history and typical or atypical clinical symptoms of malaria. The nucleic acid test of malaria parasite is positive at the same time.
2.4 Severe cases
2.4.1 Severe cases of falciparum malaria(https://www.daowen.com)
Confirmed cases of falciparum malaria with one or more of the following clinical symptoms and in the presence of P. falciparum asexual parasitemia can be diagnoses as severe falciparum malaria, which require hospitallization.
①Impaired consciousness: A Glasgow coma score ＜ 10 in adults, or a Blantyre coma score ＜ 3 in children.
②Weakness: patients can’t stand, sit or walk alone without assistance.
③Multiple convulsions: more than two or more seizures within 24 hours.
④Acidosis: a base deficit of ＞ 8mEq/L, or serum bicarbonate concentration ＜ 15 mmol/L, or venous blood lactate concentration≥ 5 mmol/L. The clinical manifestation of severe acidosis is respiratory distress (that is, rapid, deep laboured breathing).
⑤Hypoglycemia: whole blood or serum glucose concentration ＜ 2.2 mmol/L ( ＜ 40 mg/dL).
⑥Severe malarial anemia: hemoglobin concentration ≤5 g/dL or hematocrit ≤ 15% in children under 12 years old (hemoglobin concentration ＜ 7 g/dL or hematocrit ≤ 20% in adults), with a parasite count ＞ 10,000 /μL.
⑦Renal injury: the concentration of whole blood or serum creatinine ＞ 265 μmol/L (3 mg/dL) or blood urea ＞ 20 mmol/L.
⑧Jaundice: whole blood or serum bilirubin ＞ 50 μmol/L (3 mg/dL). with a parasite count ＞ 100,000/μL.
⑨Pulmonary edema: Radiologically confirmed or blood oxygen saturation ＜ 92% in room air with a respiratory rate ＞ 30/min, usually accompanied by chest indrawing and crepitations on auscultation.
⑩Significant bleeding: including recurrent or persistent bleeding from nasal, gingival or venepuncture sites, hematemesis or melena.
⑪Shock: compensatory shock is defined as a blood recharge test ≥ 3 seconds or a temperature gradient change in the leg (middle to proximal limb), but no hypertension. Uncompensated shock is defined as impaired blood perfusion (characterized by cool extremities or prolonged capillary refill), accompanied by systolic blood pressure ＜ 70 mmHg in children and ＜ 80 mmHg in adults.
⑫Hyperparasitaemia: the infection rate of erythrocyte is more than 10%.
2.4.2 Severe cases of vivax malaria
They are the same as the severe cases of falciparum malaria. However, there shall be no parasite density threshold.
2.4.3 Severe cases of knowlesi malaria
They are the same as severe cases of falciparum malaria. However, it should be noted:
①Plasmodium knowlesi hyperparasitaemia: parasite density ＞ 100,000/μL.
②Parasite density with jaundice ＞ 20,000/μL.