A Retrospective Study of Severe Plasmodium Vivax

Study Overview
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Brief Summary
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Historically, Plasmodium vivax has been termed benign due to its non-life threatening clinical course and since the 1800's this view has been cultivated as demonstrated by the use of the term benign tertian malaria to describe the infection.However over the last 15 years, more severe P. vivax malaria is being reported, causing concern that severe P. vivax malaria is under diagnosed. The definition of severe P. vivax malaria borrows from P. falciparum and is primarily one of exclusion. Species PCR (polymerase chain reaction) is the only way to prove P. vivax mono-infection but is expensive and requires skilled staff and technology. In resource constrained settings, diagnostic testing is not available for detection of most non-malarial infections further affecting the ability to determine whether severe symptoms are due to P. vivax malarial infection or a concomitant one. Retrospective studies from India, Pakistan, Indonesia, Papua New Guinea and Sudan support the existence of severe P. vivax malaria. However, inconsistent methodologies, definitions of severity, and use of diagnostic tests to exclude concomitant infection do not allow for standardised assessments for severe P. vivax infection across studies. A review by Baird, highlighted that the risk of being classed as suffering from severe illness was only minimally higher in P. falciparum than in P. vivax, but was unable to combine the data as a meta-analysis. The primary reported symptoms for severe P. vivax included severe anaemia particularly in children, severe thrombocytopaenia, respiratory distress, neurological syndromes (coma or seizures), renal and hepatic failure. Prospective studies have shown similar results. Tjitra et al showed that 23% (675 of 2,937) patients admitted with microscopically diagnosed P. vivax infections in Papua, Indonesia had severe disease and that the risk of severe malaria was significantly higher when admitted with P. vivax than with P. falciparum. In studies from Papua New Guinea, few differences between the clinical presentation of P. falciparum and P. vivax were found in children with severe malaria. This appears to be similar in populations from Sudan, Pakistan and India. In contrast, in Thailand, anecdotal observations note a low prevalence of severe P. vivax infections. The WHO criteria to assess severe P. falciparum have been extrapolated to P. vivax. In the 2015 WHO malaria guidelines some criteria now account for P. vivax, such as removing a minimum parasitaemia when assessing for severe anaemia. Whilst these criteria may not be the most sensitive tool to define severe P. vivax infections, it is used for this purpose. It has been suggested that additional clinical information may be necessary to define truly severe P. vivax cases. In order to describe the characteristics of the severity of P. vivax infections in north-western Thailand, we will perform a retrospective review of annual reports of the outpatient database, the inpatient database and eligible inpatient medical records from 2001 to 2016. The WHO malaria guidelines and additional clinical information will be used to assess the severity of infection and thus, a rate of severe P. vivax can be determined.

Official Title
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A Retrospective Study to Assess the Rate of Plasmodium Vivax Infections Presenting With Severe Symptoms From 2001 to 2016 in North-western Thailand

Conditions
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Malaria, Vivax

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients voluntarily presented at SMRU clinic during 2001-2016 with a diagnosis of P. vivax mono-infection Exclusion Criteria: Patients voluntarily presented at SMRU clinic during 2001-2016 with fever and were seeking consultation for the treatment of malaria or other infections.
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The ratio of the number of severe cases determined to be caused by P. vivax to the number of outpatient cases treated for P. vivax |  | 1 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Compare the age of inpatient cases that meet or do not meet the 2015 WHO criteria for severe P. vivax |  | 1 year | 
| Compare the sex of inpatient cases that meet or do not meet the 2015 WHO criteria for severe P. vivax |  | 1 year | 
| Compare the medical history of inpatient cases that meet or do not meet the 2015 WHO criteria for severe P. vivax |  | 1 year | 
| Compare the parasitaemia of inpatient cases that meet or do not meet the 2015 WHO criteria for severe P. vivax |  | 1 year | 
| Compare the duration of hospital stay of inpatient cases that meet or do not meet the 2015 WHO criteria for severe P. vivax |  | 1 year | 
| Compare the use of intravenous anti-malarial of inpatient cases that meet or do not meet the 2015 WHO criteria for severe P. vivax |  | 1 year | 
| Compare the blood transfusion of inpatient cases that meet or do not meet the 2015 WHO criteria for severe P. vivax |  | 1 year | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Severe malaria, plasmodium vivax