Thrombocytopenia in malaria: who cares?

Abstract

Key words: Plasmodium falciparum -Plasmodium vivax -malaria -thrombocytopenia -plateletsMalaria and thrombocytopenia • Marcus Vinícius Guimarães Lacerda et al. 53Data on the real burden of thrombocytopenia associated with malaria is contradictory in the literature and it is not usually considered when conducting patient selection. Table I shows the major publications estimating the frequency of thrombocytopenia. Most of these data were published in the late 1990s, probably in time with the surge in the availability of affordable automated machines capable of performing full blood counts (FBC). Manual platelet counting is time-consuming and usually needs to be requested by the physician with the routine blood count in most of the endemic areas for malaria. In only three publications is there an adequate randomised enrollment of patients with appropriate sample size calculation to estimate the frequency of bleeding and its association with the respective platelet count (Lacerda 2007, Silva 2009, Kochar et al. 2010. Only one study has ruled out other common causes of thrombocytopenia that are also endemic in the studied area (Lacerda 2007). There is a wide range of thrombocytopenia occurrence in these reports, which may be explained by distinct selection criteria of the enrolled patients. There are also differences in the selection of outpatients or inpatients from tertiary care centres that tend to present with severe thrombocytopenia. Furthermore, clinical manifestations of thrombocytopenia are usually described as case reports and most of these are due to P. vivax (Table II).In 2005, 138 of 684 (20.1%) malarial cases hospitalised in a tertiary care centre in Manaus had thrombocytopenia as the cause of admission, which corresponded to 6.8% of hospitalisations due to all causes in this reference institution (unpublished observations). Hospitalisation, however, does not add any benefit to the patient and because there is no evidence for any intervention, this simply increases public health costs in underdeveloped and under-resourced areas.Pathogenesis of malarial thrombocytopenia -Coagulation disturbances -A study based on 31 American soldiers in Vietnam with chloroquine-resistant falciparum malaria noted the following changes in the acute phase of the disease using the same patients as their own controls during convalescence: decrease in the platelet count and prothrombim activation time, increase in the activated thromboplastin time, and reduction in factors V, VII and VIII with normal fibrinogen (Dennis et al. 1967). This report suggested that thrombocytopenia was simply a consequence of the coagulation disorders presented by these patients, an idea that persisted for many decades in the literature. In another series of 21 patients with falciparum malaria, six had developed disseminated intravascular coagulation (DIC). The authors noted that the patients with more severe thrombocytopenia also had DIC and that there was correlation between platelet count and C3 protein levels. However, the reduction in C3 was pr...

Platelet profile is associated with clinical complications in patients with vivax and falciparum malaria in Colombia

“…The evidence is mixed regarding the existence of a correlation between platelet count (PC) and parasitemia [8][9][10][12][13][14] . In a systematic review, Lacerda et al found no differences in the frequency of thrombocytopenia across species of Plasmodium; the frequency of thrombocytopenia ranged from 24-94% in all studies 6 . The frequency of thrombocytopenia ranged from 8.0-64.2% in Colombian patients [15][16][17] .…”

“…Hematological changes, especially anemia and thrombocytopenia, are common 6,7 . Thrombocytopenia has been associated with Plasmodium knowlesi 8 , Plasmodium falciparum 9 , Plasmodium vivax, Plasmodium ovale 10 and Plasmodium malariae infections 11 .…”

Study of acute febrile illness with thrombocytopenia in a tertiary care centre

“…4 Several studies have shown that arboviral infections like dengue fever, chickugunya, kyasanur forest diseases and scrub typhus and leptospirosis and malaria, military tuberculosis typhoid and Human immunodeficiency causes fever and thrombocytopenia. 5,6 There is seasonal variation in the epidemic of fever. At times non-infective causes and drugs can also cause thrombocytopenia and fever.…”

An Autochthonous Case of Severe Plasmodium knowlesi Malaria in Thailand

“…13,14 Although thrombocytopenia is a common finding in all non-zoonotic human malaria, severe thrombocytopenia ( 20,000/mL of blood) has been reported in severe knowlesi malaria. 2,3,15 Despite remarkably low platelet levels in this patient (8,000 to 9000/μL), clinical bleeding was not observed during the course of infection. Meanwhile, atypical (or reactive) lymphocytosis and monocytosis in this patient that have also been frequently identified in acute falciparum and vivax malaria could have arisen from host immune responses culminating in destroying intraerythrocytic parasites as their levels return to normal during recovery.…”