Factors associated with recurrent Plasmodium vivax malaria in Porto Velho, Rondônia State, Brazil, 2009.

This open retrospective cohort study aimed to describe the incidence of recurrent Plasmodium vivax malaria and associated factors in Porto Velho, Rondônia State, Brazil, in 2009. Data were collected from the National Information System for Malaria Epidemiological Surveillance. There were 23,365 reported P. vivax malaria cases in 2009, 23% of which were classified as relapses. Incidence density of P. vivax recurrence was 45.1/100 patient-years, mostly occurring between the 4th and 13th week after initiating treatment. Male gender, shorter time since onset of symptoms, and higher parasitemia in the initial infection increased the risk of relapse during the year, with a 10% reduction in relative risk for longer symptoms and 11% and 15% increases in relative risk for males and higher initial parasitemia, respectively. However, the results show low clinical relevance for these associations, thereby limiting their applicability to decision-making at the public health level.

Factors associated with recurrent Plasmodium vivax malaria in Porto Velho, Rondônia State, Brazil, 2009 / Fatores associados às recidivas de malária causada por Plasmodium vivax no Município de Porto Velho, Rondônia, Brasil, 2009 / Fatores associados às recidivas de malária causada por Plasmodium vivax no Município de Porto Velho, Rondônia, Brasil, 2009 / Factores asociados a las recidivas de malaria, causada por Plasmodium vivax, en el municipio de Porto Velho, Rondônia, Brasil, 2009

This open retrospective cohort study aimed to describe the incidence of recurrent Plasmodium vivax malaria and associated factors in Porto Velho, Rondônia State, Brazil, in 2009. Data were collected from the National Information System for Malaria Epidemiological Surveillance. There were 23,365 reported P. vivax malaria cases in 2009, 23% of which were classified as relapses. Incidence density of P. vivax recurrence was 45.1/100 patient-years, mostly occurring between the 4th and 13th week after initiating treatment. Male gender, shorter time since onset of symptoms, and higher parasitemia in the initial infection increased the risk of relapse during the year, with a 10% reduction in relative risk for longer symptoms and 11% and 15% increases in relative risk for males and higher initial parasitemia, respectively. However, the results show low clinical relevance for these associations, thereby limiting their applicability to decision-making at the public health level.

Estudo de coorte histórica aberta, construída com informações registradas no Sistema de Informação de Vigilância Epidemiológica da Malária, com objetivo de descrever a incidência e os fatores associados à recidiva de malária causada pelo Plasmodium vivax em Porto Velho, Rondônia, Brasil. Foram notificados 23.365 casos de malária por P. vivax no município, sendo que 23% deles apresentaram recidiva no decorrer de 2009. A densidade de incidência de recidivas foi de 45,1/100 pacientes-ano, ocorrendo, principalmente, entre a 4a e a 13a semana após o início do tratamento. Ser homem, ter menos tempo de sintomas e ter maior nível de parasitemia na infecção inicial aumentaram o risco de recidiva no decorrer do ano, com 10% de redução relativa do risco para maior tempo de sintomas e de 11% e 15% de incremento relativo do risco para o sexo masculino e maiores níveis de parasitemia, respectivamente. Contudo, os resultados demonstram baixa relevância clínica das associações encontradas, comprometendo a sua aplicabilidade na tomada de decisão em nível de saúde pública.

Estudo de coorte histórica aberta, construída com informações registradas no Sistema de Informação de Vigilância Epidemiológica da Malária, com objetivo de descrever a incidência e os fatores associados à recidiva de malária causada pelo Plasmodium vivax em Porto Velho, Rondônia, Brasil. Foram notificados 23.365 casos de malária por P. vivax no município, sendo que 23% deles apresentaram recidiva no decorrer de 2009. A densidade de incidência de recidivas foi de 45,1/100 pacientes-ano, ocorrendo, principalmente, entre a 4a e a 13a semana após o início do tratamento. Ser homem, ter menos tempo de sintomas e ter maior nível de parasitemia na infecção inicial aumentaram o risco de recidiva no decorrer do ano, com 10% de redução relativa do risco para maior tempo de sintomas e de 11% e 15% de incremento relativo do risco para o sexo masculino e maiores níveis de parasitemia, respectivamente. Contudo, os resultados demonstram baixa relevância clínica das associações encontradas, comprometendo a sua aplicabilidade na tomada de decisão em nível de saúde pública. Recidiva; Plasmodium vivax; Malária.

Estudio de cohorte histórica abierta, construida con información registrada en el Sistema de Información de Vigilancia Epidemiológica de la Malaria, con el objetivo de describir la incidencia y los factores asociados a la reaparición de malaria, causada por el Plasmodium vivax, en Porto Velho, Rondônia, Brasil. Se notificaron 23.365 casos de malaria por P. vivax en el municipio, donde un 23% de ellos presentaron recidiva a lo largo del 2009. La densidad de incidencia de recidivas fue de 45,1/100 pacientes-año, produciéndose, principalmente, entre la 4ª y la 13ª semana tras el inicio del tratamiento. Ser hombre, tener menos tiempo síntomas y tener un mayor nivel de parasitemia en la infección inicial aumentaron el riesgo de recidiva a lo largo del año, con un 10% de reducción relativa del riesgo, para un mayor tiempo de síntomas, y de un 11% y 15% de incremento relativo del riesgo para el sexo masculino y mayores niveles de parasitemia, respectivamente. No obstante, los resultados demostraron baja relevancia clínica de las asociaciones encontradas, comprometiendo su aplicabilidad en la toma de decisiones dentro de la salud pública.

Assumed white blood cell count of 8,000 cells/µL overestimates malaria parasite density in the Brazilian Amazon.

Quantification of parasite density is an important component in the diagnosis of malaria infection. The accuracy of this estimation varies according to the method used. The aim of this study was to assess the agreement between the parasite density values obtained with the assumed value of 8,000 cells/µL and the automated WBC count. Moreover, the same comparative analysis was carried out for other assumed values of WBCs. The study was carried out in Brazil with 403 malaria patients who were infected in different endemic areas of the Brazilian Amazon. The use of a fixed WBC count of 8,000 cells/µL to quantify parasite density in malaria patients led to overestimated parasitemia and resulted in low reliability when compared to the automated WBC count. Assumed values ranging between 5,000 and 6,000 cells/µL, and 5,500 cells/µL in particular, showed higher reliability and more similar values of parasite density when compared between the 2 methods. The findings show that assumed WBC count of 5,500 cells/µL could lead to a more accurate estimation of parasite density for malaria patients in this endemic region.

In vitro antimalarial activity of tigecycline against Plasmodium falciparum culture-adapted reference strains and clinical isolates from the Brazilian Amazon.

INTRODUCTION: We evaluated the in vitro antimalarial activity of tigecycline as an alternative drug for the treatment of severe malaria. METHODS: A chloroquine-sensitive Plasmodium falciparum reference strain, a chloroquine-resistant reference strain, and three clinical isolates were tested for in vitro susceptibility to tigecycline. A histidine-rich protein in vitro assay was used to evaluate antimalarial activity. RESULTS: The geometric-mean 50% effective concentration (EC50%) of tigecycline was 535.5 nM (confidence interval (CI): 344.3-726.8). No significant correlation was found between the EC50% of tigecycline and that of any other tested antimalarial drug. CONCLUSIONS: Tigecycline may represent an alternative drug for the treatment of patients with severe malaria.

In vitro antimalarial activity of tigecycline against Plasmodium falciparum culture-adapted reference strains and clinical isolates from the Brazilian Amazon

Introduction: We evaluated the in vitro antimalarial activity of tigecycline as an alternative drug for the treatment of severe malaria. Methods: A chloroquine-sensitive Plasmodium falciparum reference strain, a chloroquine-resistant reference strain, and three clinical isolates were tested for in vitro susceptibility to tigecycline. A histidine-rich protein in vitro assay was used to evaluate antimalarial activity. Results: The geometric-mean 50% effective concentration (EC50%) of tigecycline was 535.5 nM (confidence interval (CI): 344.3-726.8). No significant correlation was found between the EC50% of tigecycline and that of any other tested antimalarial drug. Conclusions: Tigecycline may represent an alternative drug for the treatment of patients with severe malaria. .