Molecular survey of Piroplasmida, Hepatozoon spp. and Anaplasmataceae in anemic and thrombocytopenic dogs from Uruguay.

Canine tick-borne diseases, such as babesiosis, rangeliosis, hepatozoonosis, anaplasmosis and ehrlichiosis, are of veterinarian relevance, causing mild or severe clinical cases that can lead to the death of the dog. The aim of this study was detecting tick-borne protozoan and rickettsial infections in dogs with anemia and/or thrombocytopenia in Uruguay. A total of 803 domestic dogs were evaluated, and 10% were found positive (detected by PCR) at least for one hemoparasite. Sequence analysis confirmed the presence of four hemoprotozoan species: Rangelia vitalii, Babesia vogeli, Hepatozoon canis and Hepatozoon americanum, and the rickettsial Anaplasma platys. The most detected hemoparasite was R. vitalii, followed by H. canis and A. platys. This is the first report of B. vogeli in Uruguay and the second report of H. americanum in dogs from South America. The results highlight the importance for veterinarians to include hemoparasitic diseases in their differential diagnosis of agents causing anemia and thrombocytopenia.

Increased platelet distribution width and reduced IL-2 and IL-12 are associated with thrombocytopenia in Plasmodium vivax malaria.

BACKGROUND: Thrombocytopenia in malaria involves platelet destruction and consumption; however, the cellular response underlying this phenomenon has still not been elucidated. OBJECTIVE: To find associations between platelet indices and unbalanced Th1/Th2/Th17 cytokines as a response to thrombocytopenia in Plasmodium vivax infected (Pv-MAL) patients. METHODS: Platelet counts and quantification of Th1/Th2/Th17 cytokine levels were compared in 77 patients with uncomplicated P. vivax malaria and 37 healthy donors from the same area (endemic control group - ENCG). FINDINGS: Thrombocytopenia was the main manifestation in 55 patients, but was not associated with parasitaemia. The Pv-MAL patients showed increases in the mean platelet volume (MPV), which may be consistent with larger or megaplatelets. Contrary to the findings regarding the endemic control group, MPV and platelet distribution width (PDW) did not show an inverse correlation, due the increase in the heterogeneity of platelet width. In addition, the Pv-MAL patients presented increased IL-1ß and reduced IL-12p70 and IL-2 serum concentrations. Furthermore, the reduction of these cytokines was associated with PDW values. MAIN CONCLUSIONS: Our data demonstrate that an increase in MPV and the association between reductions of IL-2 and IL-12 and PDW values may be an immune response to thrombocytopenia in uncomplicated P. vivax malaria.

Increased platelet distribution width and reduced IL-2 and IL-12 are associated with thrombocytopenia in Plasmodium vivax malaria

BACKGROUND Thrombocytopenia in malaria involves platelet destruction and consumption; however, the cellular response underlying this phenomenon has still not been elucidated. OBJECTIVE To find associations between platelet indices and unbalanced Th1/Th2/Th17 cytokines as a response to thrombocytopenia in Plasmodium vivax infected (Pv-MAL) patients. METHODS Platelet counts and quantification of Th1/Th2/Th17 cytokine levels were compared in 77 patients with uncomplicated P. vivax malaria and 37 healthy donors from the same area (endemic control group - ENCG). FINDINGS Thrombocytopenia was the main manifestation in 55 patients, but was not associated with parasitaemia. The Pv-MAL patients showed increases in the mean platelet volume (MPV), which may be consistent with larger or megaplatelets. Contrary to the findings regarding the endemic control group, MPV and platelet distribution width (PDW) did not show an inverse correlation, due the increase in the heterogeneity of platelet width. In addition, the Pv-MAL patients presented increased IL-1β and reduced IL-12p70 and IL-2 serum concentrations. Furthermore, the reduction of these cytokines was associated with PDW values. MAIN CONCLUSIONS Our data demonstrate that an increase in MPV and the association between reductions of IL-2 and IL-12 and PDW values may be an immune response to thrombocytopenia in uncomplicated P. vivax malaria.

Presentation of hemolytic and hemorrhagic rangeliosis in Cerdocyon thous.

Rangeliosis, caused by protozoan Rangelia vitalii, is transmitted by the tick Amblyomma aureolatum. The disease is characterized by hemolytic and hemorrhagic disorder and has been described in dogs and other wild canids. The aim of this study was to compare clinicopathological findings and laboratory results of a Rangelia infection in a crab-eating fox (Cerdocyon thous) with those of canine rangeliosis. The zoo of Universidade de Caxias do Sul, received a crab-eating fox with marked jaundice in mucous membranes, dark-colored stools and neurological signs. The animal underwent an ear tip smear examination and blood collection for complete blood counts, serum biochemistry and PCR. Free-living and intraerythrocytic pyriform structures consistent with R. vitalii were found in the blood smear of the ear tip. The erythrogram revealed normocytic normochromic anemia, moderate macrocytosis, polychromasia and metarubricytosis. The leukogram revealed leukocytosis with neutrophilia and monocytosis, as well as severe thrombocytopenia. Serum biochemistry showed hypoproteinemia, hypoalbuminemia and elevated levels of urea and creatinine. The treatment was performed with imidocarb hydrochloride and dexamethasone, however 24 h after initiation of treatment the animal died. Macroscopic examination revealed jaundice, subcutaneous edema, enlarged superficial lymph nodes, splenomegaly, and hemorrhage of internal organs. Histological sections of the cerebellum, lung, pancreas, intestine and heart were consistent with R. vitalii infection of the vascular endothelium. Pathological and hematological findings were similar to those found in infected dogs, with clinical presentation characterized by hemolytic anemia and hemorrhage. The description of this case showed that C. thous does not only serve as reservoir of R. vitalii but may also develop disease.

Molecular detection of vector borne pathogens in anemic and thrombocytopenic dogs in southern Brazil / Detecção molecular de patógenos transmitidos por vetores em cães anemicos e trombocitopenicos no Sul do Brasil

Abstract Arthropod-borne pathogens are medically important because of their ability to cause diseases in their hosts. The purpose of this study was to detect the occurrence of Ehrlichia spp., piroplasmids and Hepatozoon spp. in dogs with anemia and thrombocytopenia in southern Brazil. EDTA-whole blood was collected from 75 domestic dogs presenting anemia or/and thrombocytopenia from Guarapuava, state of Paraná, Brazil. DNA samples were subjected to conventional PCR assays for Ehrlichia spp. (dsb), piroplasmids (18S rRNA) and Hepatozoon spp. (18S rRNA), followed by sequencing and phylogenetic analyses. Among the 75 dogs, one (1.33%) was positive for Hepatozoon sp. and six (8%) were positive for piroplasmids in 18S rRNA cPCR assays. None of the dogs showed positive results in Ehrlichia spp.-cPCR targeting dsb gene. The phylogenetic analyses revealed that three piroplasm sequences were clustered with Rangellia vitalii, while one sequence was grouped with B. vogeli. The only sequence obtained from Hepatozoon spp.-PCR protocol was pooled with H. canis. Therefore, there is urgent need for differential molecular diagnosis of the two piroplasm species cited as etiological agents in clinical cases of canine hemoparasitic diseases, given the higher pathogenic potential of R. vitalii than of B. vogeli.

Resumo Agentes transmitidos por artrópodes têm grande importância na medicina veterinária devido à sua capacidade de causar doenças graves em seus hospedeiros. O presente estudo objetivou investigar a ocorrência de três patógenos transmitidos por vetores, Ehrlichia canis, Rangelia vitalii e Hepatozoon canis, em cães na região sul do Brasil. Foram coletadas amostras de sangue total de 75 cães domésticos que apresentavam anemia e/ou trombocitopenia, em Guarapuava, Paraná, Brasil. As amostras de DNA foram submetidas à técnica de PCR convencional para E. canis (dsb), piroplasmídeos (18S rRNA) e Hepatozoon spp. (18S rRNA), seguida de sequenciamento e análises filogenéticas. Das 75 amostras, uma (1,33%) foi positiva para Hepatozoon spp. e seis (8%) foram positivas para Babesia spp. Nenhuma amostra mostrou resultados positivos para Ehrlichia spp. utilizando a detecção pelo gene dsb. As análises filogenéticas revelaram que três sequências obtidas foram agrupadas no mesmo clado que R. vitalii , enquanto uma foi agrupada juntamente com B. vogeli. A única sequência obtida pelo protocolo de PCR para Hepatozoon spp. foi agrupada juntamente com H. canis. Assim, é justificada necessidade de diferenciação das espécies de piroplasmas, através do diagnóstico molecular, como agentes etiológicos nos casos clínicos de hemoparasitose canina, considerando o potencial patogênico de R. vitalii quando comparado à B. vogeli.

Correlation between the values of circulating blood elements with the size of spleen in the presence of schistosomal splenomegaly

Abstract Purpose: To evaluate a possible relationship between the size of the spleen and values of circulating blood elements in patients with schistosomatic splenomegaly. Methods: ixty one patients with hepatosplenic schistosomiasis mansoni underwent a clinical exam and peripheral venous blood was collected for a hemogram. The erythrocyte, hemoglobin, hematocrit, leukocyte, and platelet values were determined. All patients underwent abdominal ultrasound to measure the spleen. The hematological test results were compared to the size of the spleen. Results: The size of the spleen varied from 14.0 to 28.4 (19.9 ± 3.7) cm according to the ultrasound image. Thrombocytopenia was observed 58 (95%) patients, leukopenia in 55 (90%) patients, and anemia in 32 (52.4%) patients. Leukopenia was proportional to splenomegaly. Conclusion: Schistosomal splenomegaly leads to leukopenia in direct proportion to the size of the spleen.

Molecular detection of vector borne pathogens in anemic and thrombocytopenic dogs in southern Brazil.

Arthropod-borne pathogens are medically important because of their ability to cause diseases in their hosts. The purpose of this study was to detect the occurrence of Ehrlichia spp., piroplasmids and Hepatozoon spp. in dogs with anemia and thrombocytopenia in southern Brazil. EDTA-whole blood was collected from 75 domestic dogs presenting anemia or/and thrombocytopenia from Guarapuava, state of Paraná, Brazil. DNA samples were subjected to conventional PCR assays for Ehrlichia spp. (dsb), piroplasmids (18S rRNA) and Hepatozoon spp. (18S rRNA), followed by sequencing and phylogenetic analyses. Among the 75 dogs, one (1.33%) was positive for Hepatozoon sp. and six (8%) were positive for piroplasmids in 18S rRNA cPCR assays. None of the dogs showed positive results in Ehrlichia spp.-cPCR targeting dsb gene. The phylogenetic analyses revealed that three piroplasm sequences were clustered with Rangellia vitalii, while one sequence was grouped with B. vogeli. The only sequence obtained from Hepatozoon spp.-PCR protocol was pooled with H. canis. Therefore, there is urgent need for differential molecular diagnosis of the two piroplasm species cited as etiological agents in clinical cases of canine hemoparasitic diseases, given the higher pathogenic potential of R. vitalii than of B. vogeli.

Correlation between the values of circulating blood elements with the size of spleen in the presence of schistosomal splenomegaly.

PURPOSE: To evaluate a possible relationship between the size of the spleen and values of circulating blood elements in patients with schistosomatic splenomegaly. METHODS: ixty one patients with hepatosplenic schistosomiasis mansoni underwent a clinical exam and peripheral venous blood was collected for a hemogram. The erythrocyte, hemoglobin, hematocrit, leukocyte, and platelet values were determined. All patients underwent abdominal ultrasound to measure the spleen. The hematological test results were compared to the size of the spleen. RESULTS: The size of the spleen varied from 14.0 to 28.4 (19.9 ± 3.7) cm according to the ultrasound image. Thrombocytopenia was observed 58 (95%) patients, leukopenia in 55 (90%) patients, and anemia in 32 (52.4%) patients. Leukopenia was proportional to splenomegaly. CONCLUSION: Schistosomal splenomegaly leads to leukopenia in direct proportion to the size of the spleen.

Are respiratory complications of Plasmodium vivax malaria an underestimated problem?

BACKGROUND: Respiratory complications are uncommon, but often life-threatening features of Plasmodium vivax malaria. This study aimed to estimate the prevalence and lethality associated with such complications among P. vivax malaria patients in a tertiary hospital in the Western Brazilian Amazon, and to identify variables associated with severe respiratory complications, intensive care need and death. Medical records from 2009 to 2016 were reviewed aiming to identify all patients diagnosed with P. vivax malaria and respiratory complications. Prevalence, lethality and risk factors associated with WHO defined respiratory complications, intensive care need and death were assessed. RESULTS: A total of 587 vivax malaria patients were hospitalized during the study period. Thirty (5.1%) developed respiratory complications. Thirteen (43.3%) developed severe respiratory complications, intensive care was required for 12 (40%) patients and 5 (16.6%) died. On admission, anaemia and thrombocytopaenia were common findings, whereas fever was unusual. Patients presented different classes of parasitaemia and six were aparasitaemic on admission. Time to respiratory complications occurred after anti-malarials administration in 18 (60%) patients and progressed very rapidly. Seventeen patients (56.7%) had comorbidities and/or concomitant conditions, which were significantly associated to higher odds of developing severe respiratory complications, need for intensive care and death (p < 0.05). CONCLUSION: Respiratory complications were shown to be associated with significant mortality in this population. Patients with comorbidities and/or concomitant conditions require special attention to avoid this potential life-threatening complication.

Thrombocytopenia as a marker of liver steatosis in a low-endemic area for schistosomiasis mansoni.

INTRODUCTION:: Thrombocytopenia is commonly found in patients living in highly endemic areas for Schistosoma mansoni. Recently, different degrees of liver steatosis have also been associated with low platelet counts worldwide. We investigated the association of platelet counts with hepatosplenic schistosomiasis and with liver steatosis in an area of low prevalence of schistosomiasis in Brazil. METHOD:: Pains, a city in the state of Minas Gerais, Brazil, had a population of 8,307 inhabitants and a schistosomiasis prevalence of 8%. Four micro-areas comprising 1,045 inhabitants were selected for this study. Blood sample was collected and a complete blood count (CBC) was performed. Eighty-seven (87) patients had low platelet counts (group 1 - 8.3%) and 94 volunteers presenting normal CBC were randomized (group 2 - 8.9%). They underwent clinical and ultrasound examinations. Liver steatosis was determined as either present or absent using abdominal ultrasound. A spleen > 12 cm in length, measured by ultrasound (US), was considered to be increased. Data collected were analyzed using SPSS software version 19.0. RESULTS:: Twenty-two patients (22/25.3%) in group 1 had liver steatosis compared with 11 volunteers (11.7%) in group 2 (p=0.02). Hepatosplenic schistosomiasis was diagnosed in two patients (p>0.05). CONCLUSION:: Thrombocytopenia was not a good marker of hepatosplenic schistosomiasis mansoni in a low prevalence area in Brazil. Liver steatosis was associated with thrombocytopenia in our study.

Thrombocytopenia as a marker of liver steatosis in a low-endemic area for schistosomiasis mansoni / Trombocitopenia como marcador de esteatose hepática em áreas de baixa endemicidade de esquistossomose mansoni

Summary Introduction: Thrombocytopenia is commonly found in patients living in highly endemic areas for Schistosoma mansoni. Recently, different degrees of liver steatosis have also been associated with low platelet counts worldwide. We investigated the association of platelet counts with hepatosplenic schistosomiasis and with liver steatosis in an area of low prevalence of schistosomiasis in Brazil. Method: Pains, a city in the state of Minas Gerais, Brazil, had a population of 8,307 inhabitants and a schistosomiasis prevalence of 8%. Four micro-areas comprising 1,045 inhabitants were selected for this study. Blood sample was collected and a complete blood count (CBC) was performed. Eighty-seven (87) patients had low platelet counts (group 1 - 8.3%) and 94 volunteers presenting normal CBC were randomized (group 2 - 8.9%). They underwent clinical and ultrasound examinations. Liver steatosis was determined as either present or absent using abdominal ultrasound. A spleen > 12 cm in length, measured by ultrasound (US), was considered to be increased. Data collected were analyzed using SPSS software version 19.0. Results: Twenty-two patients (22/25.3%) in group 1 had liver steatosis compared with 11 volunteers (11.7%) in group 2 (p=0.02). Hepatosplenic schistosomiasis was diagnosed in two patients (p>0.05). Conclusion: Thrombocytopenia was not a good marker of hepatosplenic schistosomiasis mansoni in a low prevalence area in Brazil. Liver steatosis was associated with thrombocytopenia in our study.

Resumo Introdução: Trombocitopenia é um achado comum em pacientes que residem em áreas com alta endemicidade de esquistossomose mansônica. Recentemente, diferentes graus de esteatose hepática também têm sido associados a níveis baixos de plaquetas em todo o mundo. Investigamos a associação de níveis séricos de plaquetas com a forma grave da esquistossomose e com esteatose hepática em área de baixa prevalência de esquistossomose no Brasil. Método: Pains, cidade localizada no estado de Minas Gerais/Brasil, tem população de 8.307 habitantes e prevalência de esquistossomose de 8%. Em quatro microáreas dessa região, 1.045 habitantes foram avaliados para o estudo. Amostra de sangue foi coletada para realização do hemograma. Oitenta e sete (87) pessoas com níveis baixos de plaquetas formaram o grupo 1 (8,3%), e 94 voluntários com hemograma normal foram randomizados para compor o grupo 2 (8,9%). Todos os participantes dos grupos 1 e 2 foram submetidos a exame clínico e ultrassonografia (US) abdominal. Esteatose hepática foi caracterizada como presente ou ausente pela ultrassonografia (US) abdominal. Baços com mais de 12 cm de comprimento à US foram considerados aumentados. Os dados coletados foram analisados pelo programa de estatística SPSS 19.0. Resultados: Vinte e dois (22) indivíduos do grupo 1 (25,3%) e 11 do grupo 2 apresentaram esteatose hepática (11,7%) (p=0,02). Esquistossomose hepatoesplênica foi diagnosticada em dois pacientes (p>0,05). Conclusão: Trombocitopenia não foi um bom marcador de esquistossomose mansônica hepatoesplênica em área de baixa prevalência da esquistossomose no Brasil. Esteatose hepática foi associada com trombocitopenia no presente estudo.

Purinergic ecto-enzymes participate in the thromboregulation in acute in mice infection by Trypanosoma cruzi.

Coagulation disorders have been described in Chagas disease with thrombocytopenia as an important event. Several mechanisms may be related to this pathogenesis, such as enzymes of the purinergic system, purine, and receptors involved in the regulation and modulation of physiological events related to hemostasis. Therefore, the aim of this study was to evaluate the activities of E-NTPDase, E-5'nucleotidase, and ecto-adenosine deaminase (E-ADA) in platelets of mice experimentally infected by Trypanosoma cruzi. Twelve female mice were used, divided into two groups (n = 6): uninfected and infected. Mice of infected group were intraperitoneally inoculated with 104 trypomastigotes of T. cruzi (strain Y). On day 12 post-infection (PI), blood samples were collected for quantitation and separation of platelets. A significant reduction in the number of platelets of infected mice (P < 0.05) was observed. The activities of E-NTPDase (ATP and ADP substrates), E-5'nucleotidase, and E-ADA in platelets increased significantly (P < 0.05) in mice infected by T. cruzi compared with uninfected animals. A negative correlation (P < 0.01)was observed between the number of platelets and ATP hydrolysis (r = -0.64), and ADP hydrolysis (r = -0.69) by E-NTPDase. Therefore, there is a response from the purinergic system activating ecto-enzymes in platelets of mice T. cruzi infected, as a compensatory effect of thrombocytopenia.

Portal vein thrombosis associated with protein C deficiency and elevated Factor VIII in hepatosplenic schistosomiasis.

Portal vein thrombosis is considered a vaso-occlusive process that can appear during the course of hepatosplenic Schistosoma mansoni, but may result from impaired portal blood flow or be associated with acquired or inherited thrombophilic factors. Here, we report the case of a 67-year-old woman who developed thrombocytopenia as a result of hypersplenism. Following the diagnosis of hepatosplenic schistosomiasis, portal vein thrombosis was detected by ultrasound examination, while haematological tests revealed low levels of protein C (43.3%) and high levels of factor VIII (183.1%). The pathogenesis of portal vein thrombosis remains unclear in some patients with S. mansoni. We recommend, therefore, that early clinical and haemostatic investigations are done to evaluate risk of portal vein thrombosis and hence avoid further complications.

Radiofrequency ablation for treatment of hypersplenism: A feasible therapeutic option.

We present a case of a patient with hypersplenism secondary to portal hypertension due to hepato-splenic schistosomiasis, which was accompanied by severe and refractory thrombocytopenia. We performed spleen ablation and measured the total spleen and ablated volumes with contrast-enhanced computed tomography and volumetry. No major complications occurred, thrombocytopenia was resolved, and platelet levels remained stable, which allowed for early treatment of the patient's underlying disease. Previous work has shown that splenic radiofrequency ablation is an attractive alternative treatment for hypersplenism induced by liver cirrhosis. We aimed to contribute to the currently sparse literature evaluating the role of radiofrequency ablation (RFA) in the management of hypersplenism. We conclude that splenic RFA appears to be a viable and promising option for the treatment of hypersplenism.

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

INTRODUCTION: Thrombocytopenia is a common complication in malaria patients. The relationship between abnormal platelet profile and clinical status in malaria patients is unclear. In low and unstable endemic regions where vivax malaria predominates, the hematologic profiles of malaria patients and their clinical utility are poorly understood. The aim of this study was to characterize the thrombograms of malaria patients from Colombia, where Plasmodium vivax infection is common, and to explore the relationship between thrombograms and clinical status. METHODS: Eight hundred sixty-two malaria patients were enrolled, including 533 (61.8%) patients infected with Plasmodium falciparum, 311 (36.1%) patients infected with Plasmodium vivax and 18 (2.1%) patients with mixed infections. RESULTS: The most frequently observed changes were low platelet count (PC) and high platelet distribution width (PDW), which were observed in 65% of patients; thrombocytopenia with <50,000 platelets/µL was identified in 11% of patients. Patients with complications had lower PC and plateletcrit (PT) and higher PDW values. A higher risk of thrombocytopenia was identified in patients with severe anemia, neurologic complications, pulmonary complications, liver dysfunction, renal impairment and severe hypoglycemia. The presence of thrombocytopenia (<150,000 platelets/µL) was associated with a higher probability of liver dysfunction. CONCLUSIONS: Young age, longer duration of illness and higher parasitemia are associated with severe thrombocytopenia. Our study showed that thrombocytopenia is related to malaria complications, especially liver dysfunction. High PDW in patients with severe malaria may explain the mechanisms of thrombocytopenia that is common in this group of patients.

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

Introduction Thrombocytopenia is a common complication in malaria patients. The relationship between abnormal platelet profile and clinical status in malaria patients is unclear. In low and unstable endemic regions where vivax malaria predominates, the hematologic profiles of malaria patients and their clinical utility are poorly understood. The aim of this study was to characterize the thrombograms of malaria patients from Colombia, where Plasmodium vivax infection is common, and to explore the relationship between thrombograms and clinical status. Methods Eight hundred sixty-two malaria patients were enrolled, including 533 (61.8%) patients infected with Plasmodium falciparum, 311 (36.1%) patients infected with Plasmodium vivax and 18 (2.1%) patients with mixed infections. Results The most frequently observed changes were low platelet count (PC) and high platelet distribution width (PDW), which were observed in 65% of patients; thrombocytopenia with <50,000 platelets/µL was identified in 11% of patients. Patients with complications had lower PC and plateletcrit (PT) and higher PDW values. A higher risk of thrombocytopenia was identified in patients with severe anemia, neurologic complications, pulmonary complications, liver dysfunction, renal impairment and severe hypoglycemia. The presence of thrombocytopenia (<150,000 platelets/µL) was associated with a higher probability of liver dysfunction. Conclusions Young age, longer duration of illness and higher parasitemia are associated with severe thrombocytopenia. Our study showed that thrombocytopenia is related to malaria complications, especially liver dysfunction. High PDW in patients with severe malaria may explain the mechanisms of thrombocytopenia that is common in this group of patients. .

Thrombocytopenia in Plasmodium vivax malaria is related to platelets phagocytosis.

BACKGROUND: Although thrombocytopenia is a hematological disorder commonly reported in malarial patients, its mechanisms are still poorly understood, with only a few studies focusing on the role of platelets phagocytosis. METHODS AND FINDINGS: Thirty-five malaria vivax patients and eight healthy volunteers (HV) were enrolled in the study. Among vivax malaria patients, thrombocytopenia (<150,000 platelets/µL) was found in 62.9% (22/35). Mean platelet volume (MPV) was higher in thrombocytopenic patients as compared to non-thrombocytopenic patients (p = 0.017) and a negative correlation was found between platelet count and MPV (r = -0.483; p = 0.003). Platelets from HV or patients were labeled with 5-chloromethyl fluorescein diacetate (CMFDA), incubated with human monocytic cell line (THP-1) and platelet phagocytosis index was analyzed by flow cytometry. The phagocytosis index was higher in thrombocytopenic patients compared to non-thrombocytopenic patients (p = 0.042) and HV (p = 0.048). A negative correlation was observed between platelet count and phagocytosis index (r = -0.402; p = 0.016). Platelet activation was assessed measuring the expression of P-selectin (CD62-P) in platelets' surface by flow cytometry. No significant difference was found in the expression of P-selectin between thrombocytopenic patients and HV (p = 0.092). After evaluating the cytokine profile (IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ and IL-17) in the patients' sera, levels of IL-6, IL-10 and IFN-γ were elevated in malaria patients compared to HV. Moreover, IL-6 and IL-10 values were higher in thrombocytopenic patients than non-thrombocytopenic ones (p = 0.044 and p = 0.017, respectively. In contrast, TNF-α levels were not different between the three groups, but a positive correlation was found between TNF-α and phagocytosis index (r = -0.305; p = 0.037). CONCLUSION/SIGNIFICANCE: Collectively, our findings indicate that platelet phagocytosis may contribute to thrombocytopenia found in vivax malaria. Finally, we believe that this study opens new avenues to explore the mechanisms involved in platelet dysfunction, commonly found in vivax malaria patients.

Genetic variability in platelet integrin α2ß1 density: possible contributor to Plasmodium vivax-induced severe thrombocytopenia.

Understanding the pathogenesis of Plasmodium vivax malaria is challenging. We hypothesized that susceptibility to P. vivax-induced thrombocytopenia could be associated with polymorphisms on relevant platelet membrane integrins: integrin α2 (C807T), and integrin ß3 (T1565C). Although ß3 polymorphism was not related with P. vivax malaria, α2 807T carriers, which show high levels of integrin α2ß1, had a higher probability for severe thrombocytopenia than wild-type carriers. This evidence of the association of integrin polymorphism and P. vivax morbidity was further demonstrated by a moderate but significant correlation between clinical disease and surface levels of the integrin α2ß1.

Thrombocytopenia in malaria: who cares?

Despite not being a criterion for severe malaria, thrombocytopenia is one of the most common complications of both Plasmodium vivax and Plasmodium falciparum malaria. In a systematic review of the literature, platelet counts under 150,000/mm³ ranged from 24-94% in patients with acute malaria and this frequency was not different between the two major species that affected humans. Minor bleeding is mentioned in case reports of patients with P. vivax infection and may be explained by medullary compensation with the release of mega platelets in the peripheral circulation by megakaryocytes, thus maintaining a good primary haemostasis. The speculated mechanisms leading to thrombocytopenia are: coagulation disturbances, splenomegaly, bone marrow alterations, antibody-mediated platelet destruction, oxidative stress and the role of platelets as cofactors in triggering severe malaria. Data from experimental models are presented and, despite not being rare, there is no clear recommendation on the adequate management of this haematological complication. In most cases, a conservative approach is adopted and platelet counts usually revert to normal ranges a few days after efficacious antimalarial treatment. More studies are needed to specifically clarify if thrombocytopenia is the cause or consequence of the clinical disease spectrum.