A Combination of the Kato-Katz Methods and ELISA to Improve the Diagnosis of Clonorchiasis in an Endemic Area, China

Abstract

BackgroundExamination of feces by light microscopy is widely used for specific parasitological diagnosis of clonorchiasis. However, the true incidence of infection is underestimated owing to the high missing diagnosis rate of this method. The enzyme-linked immunosorbent assay (ELISA) is widely used for the detection and control of clonorchiasis but the practicality of this method is unclear. The purpose of this study was to evaluate the effect of ELISA as a supplementary method for the diagnosis of clonorchiasis.Methodology/Principal FindingsThe present study recruited 2,359 clinically suspected patients from Heilongjiang Province, China. In all, 954 cases were identified as antibody-positive by immunoglobulin (IgG)-ELISA and 495 individuals were diagnosed as egg-positive by the Kato-Katz (KK) method. The seropositive and egg-negative individuals were re-examined by repeated egg counts and/or the number of KK slides and 18 (18.18%) cases were confirmed as clonorchiasis. The 40.44%, antibody-positive rate determined by IgG-ELISA was significantly higher (P<0.05) than the 21.75% egg-positive rate found by examination of feces. A Bayesian approach indicated that the prevalence of clonorchiasis in this region was 22.27% and that the sensitivity, specificity, positive predictive value and negative predictive value of IgG-ELISA were 98.7%, 76.53%, 54.66% and 99.52%, respectively. The agreement between the two methods was moderate (kappa value = 0.564). The clonorchiasis patients lived mainly along the Songhua River. The risk factors, except for ethnic factors, were estimated effectively by both methods.Conclusions/SignificanceThe present study suggested that clonorchiasis was widely distributed in Heilongjiang Province, China. The missing diagnosis rate was high using the KK technique alone. The combination of immunological methods and parasitological techniques could improve diagnostic accuracy and reduce the missing diagnosis rate. ELISA used as an auxiliary diagnostic method was realistic and practical for a large-scale screening test, monitoring the prevalence and assessing the risk factors of clonorchiasis.

Microscopic identification of possible Clonorchis/Opisthorchis infection in two Ghanaian women with undiagnosed abdominal discomfort: two case reports

“…They pose a significant threat to human health since they infect key organs such as the liver and biliary system [ 18 ]. Although most people with the infection are asymptomatic, about 5% to 10% of people with heavy fluke infections may exhibit nonspecific symptoms such as right upper quadrant abdominal pain, flatulence, and fatigue [ 1 , 3 , 4 , 10 , 19 ]. These nonspecific symptoms in infected individuals imply that several cases may go undetected.…”

“…These parameters include the nature of the operculum, shoulder rim, operculum knob, the shape, the form, length and width of the eggs as well as length-to-width ratio (LWR) and Faust-Meleney index (FMI) [ 22 ]. Currently, more specific and sensitive serological and molecular methods such as polymerase chain reaction are available for identification and differentiation [ 1 , 23 ] but these methods are expensive and require specialized skills.…”

“…Clonorchis sinensis and Opisthorchis species are important liver flukes of oriental or Chinese origin [ 1 - 4 ]. Clonorchiasis whose symptoms are indistinguishable from opisthorchiasis is one of the most neglected tropical diseases which blight the lives of millions of people worldwide and threaten the health of several others [ 5 , 6 ].…”

“…However, its incidence in non-endemic areas has been associated with importation by immigrants from endemic areas [ 13 - 15 ]. The emergence of Clonorchis or Opisthorchis in non-endemic areas has been linked to an increase in the consumption of raw or undercooked fish, expansion of water snail habitats due to rapidly growing aquacultures and increase in raw food distribution network [ 1 , 2 , 5 , 7 , 11 ].…”

Dysregulation of hepatic microRNA expression profiles with Clonorchis sinensis infection

“…Clonorchis sinensis ( C. sinensis ) is an important food-borne zoonotic parasite that causes an estimated 35 million human infections worldwide primarily throughout countries in eastern and southeast Asia, including China, Japan, Korea, and Vietnam [1, 2]. Human infection occurs by ingestion of insufficiently cooked freshwater fish harboring C. sinensis metacercariae.…”