Urinary hydatid antigen detection by coagglutination, a cost-effective and rapid test for diagnosis of cystic echinococcosis in a rural or field setting.

We describe here coagglutination (Co-A), a rapid slide agglutination test for the detection of hydatid antigen in the urine for the diagnosis of cystic echinococcosis (CE). Paired urine and serum samples were collected from 16 patients with surgically confirmed CE, 10 patients with ultrasound-proven CE, 14 patients with clinically diagnosed CE, 24 patients with various parasitic diseases other than CE, and 25 healthy control subjects. Co-A detected excreted hydatid antigen in the concentrated urine of 7 of 16 (43.75%) surgically confirmed cases, 6 of 10 (60%) ultrasound-proven cases, and 8 of 14 (57.14%) clinically diagnosed cases of CE. A false-positive reaction was observed with 12.50% of control urine specimens from patients with parasitic diseases other than CE and 12% of urine samples from healthy controls. The circulating antigen was detected in the serum in 13 of 16 (81.25%) surgically confirmed cases, 6 of 10 (60%) ultrasound-proven cases, and 13 of 14 (92.86%) clinically diagnosed cases of CE. False-positive reactions were observed with three sera (12.5%) from controls with other parasitic diseases. The low sensitivity of Co-A for detection of antigen in the urine of a patient whose serum was positive for the antigen is possibly due to low levels of antigen in the urine. Unlike the collection of blood for serum, which is an invasive procedure and also requires technical expertise and disposable syringes, urine can be collected easily and frequently without causing any inconvenience to the patient. Urine as a clinical specimen alternative to serum would be immensely useful in the diagnosis of CE, particularly in a rural or field setting. In such situations as well as in poorly equipped laboratories, Co-A has the potential to be used as a simple, rapid, and economical slide agglutination test for detection of urinary hydatid antigen in the diagnosis of CE.

Evaluation of human hydatid disease before and after surgery and chemotherapy by demonstration of hydatid antigens and antibodies in serum.

This study was performed to differentiate serologically between patients with hydatid disease which is active, and which has been successfully cured. A total of 18 cases was included. Pre-treatment serum samples were collected before surgery or chemotherapy. Post-treatment serum samples were collected at various intervals (3 days, 7 days, 1 month, 6 months, 1 year and 2 years) after surgery or chemotherapy. These sera were tested for the presence of circulating hydatid antigen (CAg) by bacterial co-agglutination (Co-A) and counter-current immunoelectrophoresis (CIEP) tests, and for circulating hydatid antibodies (CAb) by indirect haemagglutination assay (IHA). Ten and eight sera, respectively, were positive out of 11 pre-operative and pre-chemotherapeutic sera tested for CAg by the Co-A and CIEP tests. Post-operative sera collected from these cases did not show any CAg by the CIEP test. However, CAg was detected by Co-A in three and four serum samples collected on the third and seventh day, respectively, after surgical removal of the cyst. However, the CAg levels in these post-operative sera showed a gradual decline by the seventh day and were completely absent in the serum specimens collected 1 month after surgery and 6 months after chemotherapy. All the post-operative serum samples except two, collected 2 years after surgical removal of the cyst, in seven cases of old hydatid disease, were negative for CAg by both the CIEP and Co-A tests. Unlike the CAg profile, no marked differences were noted between the CAb profile of the pre- and post-treatment sera, as shown by the IHA test. Even 1 year after surgery or chemotherapy, two sera showed a marginal decrease in their CAb titre. CAb at varying titres was still detectable in all seven serum samples from old cases of hydatid disease, even 2 years after surgical removal of the cyst. This study shows the value of serial pre- and post-operative or chemotherapy estimation of CAg by Co-A and CIEP as an index of cure or of continuing hydatid infection.

Countercurrent immunoelectrophoresis test for detection of hydatid antigen in the fluid from hydatid cysts: a preliminary report.

The exact aetiology of a suspected hydatid cyst may sometimes be a diagnostic dilemma. One of the recent methods to confirm that the cysts are echinococcal in origin is the demonstration of hydatid antigens in the aspirated cystic fluid. In the present study, we evaluated the use of countercurrent immunoelectrophoresis (CIEP) to detect hydatid antigen in cyst fluids. Antibody used for detecting the antigen consisted of hyper immune sera raised in rabbits after inoculation of crude human hydatid cystic fluid antigen. Fluids were collected post-operatively from a total of 14 hydatid cysts confirmed by surgery and by histopathology. The results of the study show that the test is moderately sensitive detecting antigen in 11 (78.5%) of 14 cyst fluids. The test did not detect antigen in three other cyst fluids. The main advantage is its specificity as it was 100% specific with no reactions in control samples. Even though, sensitivity is not very high, the test is sample, inexpensive, and can rapidly diagnose hydatid aetiology of cysts and may be of help in the diagnosis of hydatid cysts in peripheral parasitology laboratories.

Detection of hydatid antigen in urine by countercurrent immunoelectrophoresis.

Hydatid antigen was demonstrated for the first time in the urine of patients with hydatid disease by countercurrent immunoelectrophoresis (CIEP). The antigen was detected in the concentrated urine of 7 of 16 (43.75% positive) patients with surgically confirmed hydatid disease, 4 of 10 (40% positive) patients with ultrasound-proven hydatid disease (daughter cysts or prominent septation and hydatid sands demonstrated by ultrasound), and 8 of 14 (57.14% positive) patients with clinically diagnosed (presumptive) hydatid disease. No antigen was detected in the concentrated urine from 24 patients with parasitic diseases other than hydatid disease. However, antigen was detected in 2 (8% false positive) of 25 concentrated urine samples collected from healthy control subjects (blood donors and students). These result suggest that the detection of hydatid antigen in the urine by CIEP is a simple, rapid, and noninvasive method of diagnosis of hydatid disease.

Detection of hydatid antigen by co-agglutination in fluid samples from hydatid cysts.

The co-agglutination (Co-A) procedure was standardized and evaluated to detect hydatid antigen in fluid samples aspirated from hydatid cysts. Samples were collected from 14 hydatid cysts in different organs (liver, 7; lung, 5; multiple abdominal cysts, 1; and kidney, 1) by surgery. Echinococcus granulosus scolices and hooklets were seen in only 6 (42.85%) samples by routine microscopy. In contrast, hydatid antigen was demonstrated in all the samples by Co-A (100% sensitivity). Co-A could be employed as a simple and rapid diagnostic procedure, as an alternative to microscopy, to confirm the hydatid aetiology of a suspected cyst.