Leptospirosis in Febrile Patients: Diagnosis by Serology and Polymerase Chain Reaction

Abstract

Introduction : Leptospirosis is a zoonotic disease   found in  all tropical and temperate areas of the world .   Humans contract leptospira through mucosal or percutaneous exposure to  environments contaminated by the urine of chronically infected animal sources mainly  rodents, dogs, pigs and cattle.

Objectives:It is known that IgM ELISA is used widely  to diagnose leptospirosis in acute stage of illness.

Our aim is to evaluate the sensitivity and specificity of a molecular technique like PCR in comparison to the serological test Pan Bio, IgM ELISA, and its usefulness as a diagnostic test in the diagnosis of leptospirosis.  

 Methods: The patients included 85 males and 15 females, age 2yrs–78 yrs, (median age, 40yrs). Common presenting symptoms were Fever, myalgia, jaundice, nausea and vomiting, oliguria and acute renal failure.Blood   samples were drawn during the acute phase of illness, 7.5 mean days from the onset of symptoms. All the samples were tested for IgM antibody by ELISA and for Leptospira DNA by PCR. Detection of antibody done by PanBio Leptospira IgM ELISA .  Detection of DNA by PCR: Extraction of DNA: was performed using the QIAGEN  mini kit.   Amplification of DNA: Primers used to amplify a 631 base-pair (bp) 5'-region of 16S rDNA of pathogenic leptospira,   Detection of DNA:  by Agarose gel electrophoresis

Results:  All  100 samples were tested by both ELISA and PCR. 35 samples (35%) were positive for the presence of IgM antibodies by ELISA.   PCR demonstrated DNA in 34 of the samples .  A total of 28 samples were positive by both ELISA and PCR. The PCR demonstrated a sensitivity of 80 % and specificity of 90%.

 Conclusions: PCR is a sensitive and specific technique which can detect the presence of DNA in the very early stage of the disease, Results of PCR can give us a presumptive diagnosis of leptospirosis in early phase of illness (1-7days) compared to pan Bio IgM ELISA. Hence  PCR together with IgM ELISA can be used to confirm the diagnosis, in  the acute stage(1-15days) of the infection.

Key words: Leptospirosis, IgM Antibody, ELISA, DNA, PCR