Detection of circulating antigens in patients with active Schistosoma haematobium infection.
An antigen-capture ELISA using monoclonal antibody (MAb) 128C3/3/21 was used to detect circulating parasite-derived antigens in the sera of patients actively infected with Schistosoma haematobium (31 males and four females, 5-25 years of age). The assay had a sensitivity of 100% (35 of 35 patients with antigen levels > 80 ng/ml) and a specificity > 99%. We used this ELISA to monitor antigenemia before treatment and one, three, and six months after treatment with a single oral dose of praziquantel (PZQ) (60 mg/kg in 20 patients or 40 mg/kg in 15 patients) and compared our findings with those indicated by other measures of disease progression. Circulating antigen levels decreased drastically after PZQ treatment (P < 0.001), with a significantly higher decrease occurring after treatment with 60 mg/kg than with 40 mg/kg. Although the mean antigen level was still significantly reduced (P < 0.001) at six months after treatment, 16 patients remained antigen-positive after six months, and nine had increased levels of antigenemia, reflecting reinfection in six patients and persistence of infection in another. We observed a correlation (r = 0.6, P < 0.01) between the level of circulating antigen and the intensity of infection as measured by egg count. We also found a direct relationship (P < 0.001) between antigen level and the severity of the disease as monitored by ultrasonography. We conclude that our ELISA may be a useful adjunct to other methods, such as ultrasonography, for monitoring the course of S. haematobium infection and treatment.
Hassan
M M
MM
Department of Parasitology, Faculty of Medicine, Zagazig University, Egypt.
Medhat
A
A
Makhlouf
M M
MM
Shata
T
T
Nafeh
M A
MA
Osman
O A
OA
Deaf
E A
EA
Galal
N
N
Fouad
Y M
YM
D000293:Adolescent; D000328:Adult; D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000276:immunology; D000947:Antigens, Helminth / Q000097:blood*; D000980:Antiplatyhelmintic Agents / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000469:parasitology; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D010270:Parasite Egg Count; D011223:Praziquantel / Q000627:therapeutic use; D012548:Schistosoma haematobium / Q000276:immunology*; D012553:Schistosomiasis haematobia / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology*; D012680:Sensitivity and Specificity; D014556:Urine / Q000469:parasitology
D000909:Antibodies, Helminth; D000911:Antibodies, Monoclonal; D000947:Antigens, Helminth; D000980:Antiplatyhelmintic Agents; D007074:Immunoglobulin G; D007073:Immunoglobulin E; D011223:Praziquantel