Immunodiagnosis of cystic echinocooccosis by antigen detection in serum, urine, and saliva samples

BACKGROUND: Cystic echinococcosis (CE) being more common in rural areas, the collection of serum may not always be possible or may be hazardous in untrained hands. The alternative, noninvasive samples like saliva and urine which are non invasive and easy to collect need to be evaluated for diagnosis of CE. AIM: The aim of this study was to evaluate hydatid antigen detection by ELISA in urine and saliva samples by comparing them with antigen detection in serum for diagnosis of CE. MATERIALS AND METHODS: Serum, saliva and urine samples were collected from 25 clinically and radiologically diagnosed CE patients, 25 clinically suspected cases of CE, 15 other parasitic disease controls and 25 healthy controls. Hydatid antigen detection was done in these samples by Enzyme linked immunosorbent assay using hyperimmune serum raised in rabbits immunized with hydatid antigen. RESULTS AND CONCLUSIONS: The sensitivity of ELISA for antigen detection in serum, saliva and urine was found to be 40%, 24% and 52% respectively. Urine showed significantly higher (p<0.05) sensitivity than that of saliva samples but not significantly higher (p>0.05) than that of serum samples. The specificity was highest for serum (92.5%) followed by saliva (87.5%) and urine (80%). There was no significant difference in antigen detection in patients with single vs multiple cysts. There was no significant difference in antigen detection in patients with hepatic vs extrahepatic cysts in serum or saliva samples but antigen positivity in urine was significantly higher (p<0.05) in hepatic cysts than that in extrahepatic cysts. The results showed that biological fluids like urine and saliva may be used as an alternative or as an adjunct to serum samples by virtue of their noninvasive, easy collection and similar sensitivity and specificity.