From the Guidelines
Malaria typically causes several characteristic changes on a complete blood count (CBC), including thrombocytopenia, anemia, and variable leukocyte counts, as seen in recent studies 1. The most common finding is thrombocytopenia (low platelet count), which occurs in a significant proportion of cases, as evidenced by a platelet count of 115,000/mL in one study 1 and 27,000/mL in another 1. Anemia is also frequently present, ranging from mild to severe depending on the duration and severity of infection, with hemoglobin levels dropping significantly, especially in Plasmodium falciparum infections, such as a hemoglobin level of 10.9 g/dL in one case 1. Leukocyte counts are variable but often show leukopenia (decreased white blood cells), though some patients may have normal or even elevated white cell counts, as seen in one study with a white blood cell count of 11,000/mL 1. The differential count might reveal monocytosis and lymphocytosis in some cases, and atypical lymphocytes may be present. In severe malaria, hemolysis can lead to elevated reticulocyte counts, decreased haptoglobin, and increased lactate dehydrogenase (LDH), as seen in one study with a lactate dehydrogenase level of 563 U/L 1. These changes reflect the parasite's life cycle within red blood cells, causing their destruction and triggering immune responses, and the severity of these CBC abnormalities often correlates with parasite density, as evidenced by a high parasitaemia value of 17% in one case 1, and can help monitor treatment response, with parameters gradually returning to normal as the infection resolves, as recommended in recent guidelines 1. Key laboratory alterations in severe malaria include severe anaemia, acidosis, hypoglycaemia, hyperparasitaemia, and serum creatinine elevation, with varying threshold values among different guidelines 1. Monitoring of CBC parameters, such as parasitaemia, hemoglobin, haptoglobin, and lactate dehydrogenase levels, is essential in managing malaria, especially in severe cases, as recommended in recent studies 1.
From the Research
Changes in Complete Blood Count (CBC) in Malaria
- Anaemia is a common finding in malaria patients, with a study showing that 97.3% of children with malaria had anaemia 2.
- Leukopenia is also observed in malaria patients, with 39% of cases in one study showing leukopenia 2 and 8.8% in another study 3.
- Thrombocytopenia is another frequent finding, with 51.3% of cases in one study showing mild thrombocytopenia 2 and 55.4% in another study 3.
- The severity of these changes can vary depending on the species of Plasmodium, with P. falciparum tends to cause more severe anaemia, leukopenia, and thrombocytopenia than P. vivax 2, 3.
Haematological Parameters and Malaria Parasitaemia
- Studies have shown that haematological parameters such as platelet count, red blood cell count, and haemoglobin level are significantly lower in malaria patients than in controls 4.
- There is a significant positive correlation between total WBC and parasitaemia, and a negative correlation between platelets, total RBC's, haemoglobin, and parasitaemia 5.
- Linear regression analysis has shown a linear relationship between parasite density and various haematological parameters, including WBC and platelet count 5.
Comparison of Haematological Profiles in Malaria Patients
- A study comparing the haematological profiles of malaria-infected adult patients and controls found that the mean values of red blood cell count, haemoglobin, and platelet count were significantly lower in the cases than the controls 4.
- Another study found that the prevalence of anaemia and thrombocytopenia in malaria patients were 39.5% and 56.3%, respectively, and that being female and having high malaria parasitemia were significantly associated with thrombocytopenia 4.