Background: Cerebral malaria and viral encephalitis are two life threatening infections having similar presentation and difficult to diagnose in absence of parasite by slide test or rapid diagnostic test and negative serological test in case of viral encephalitis and difficult to predict their prognosis.

Objective:To study the prognostic significance of serum lactate dehydrogenase (LDH) and CSF LDH in patients of cerebral malaria and viral encephalitis.

Method:After fulfilling exclusion criteria,35 encephalitis patients and 22 cerebral malaria patients are selected clinically and subjected to blood MP, Rapid Diagnostic Test(RDT) and serological tests for Herpes simplex virus(HSV)–1 and HSV–2. Controls are selected from the patients having minor surgical ailment like hernia, hydrocele without neurological, renal, hepatic or cardiac diseases who were to undergo the required surgery. Serum and cerebrospinal fluid (CSF) LDH estimation was carried out and the observations were analysed statistically.

Results:There was no significant difference of mean serum LDH level in patients with cerebral malaria or encephalitis but a significantly higher value was observed in both cases compared to controls. Mean serum LDH value was not significant among survivors and nonsurvivors of both the groups. CSF LDH was significantly high in viral encephalitis compared to cerebral malaria (P< 0.0004) and controls (P< 0.001). However CSF LDH values in cerebral malaria was significantly high compared to controls (P<0.001). Mean CSF LDH level in viral encephalitis was significantly high in non survivor compared to survivor. No such difference was observed in cerebral malaria.

Conclusion:CSF LDH has prognostic significance in viral encephalitis but not in cerebral malaria. Serum LDH is raised both in cerebral malaria and viral encephalitis but having no significant difference between them and it has no prognostic value.