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M J Doenhoff

Publications and source records attributed to M J Doenhoff.

130 records · Page 8Linked to original sources
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Seroepidemiology and serodiagnosis of schistosomiasis in Kenya using crude and purified egg antigens of Schistosoma mansoni in ELISA.

The performance of antibody detection for the diagnosis of schistosomiasis has been evaluated in Kenya. Approximately 1500 blood samples from 3 areas with endemic schistosomiasis (Schistosoma mansoni only, S. haematobium only, and a mixed infection area), and from a non-endemic control area, were tested for their antibody reactivity in an enzyme-linked immunosorbent assay (ELISA). The results were compared with infection status determined by parasitological examination. Two test antigens were used: unfractionated S. mansoni egg homogenate (SEA), and CEF6, a previously described, partially purified fraction of SEA containing 2 cationic antigens. The antigens prepared from eggs of Kenya and Puerto Rico S. mansoni isolates gave very similar results. Bloods from patients with S. haematobium infection cross-reacted significantly with the two S. mansoni antigen preparations, but reactivity against CEF6 appeared more specifically indicative of S. mansoni infection. Of 254 blood samples from schoolchildren in the non-endemic area, 100% gave ELISA optical density readings at 492 nm (OD492) < 0.20 against SEA, and 98% were < 0.20 against CEF6. With 887 blood samples from subjects of all ages in the area endemic for S. mansoni alone, using an ELISA OD492 cut-off point of 0.20, SEA and CEF6 had sensitivities of 94% and 97% respectively, and specificities of 64% and 59% respectively. Increasing the OD492 cut-off value reduced the sensitivity and increased the specificity of both test antigens. Specificity of both antigens was poor with samples from 234 children in an area endemic for both S. mansoni and S. haematobium (< 20% for both antigens at an OD492 cut-off value of 0.20).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
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An enzyme-linked immunosorbent assay using Schistosoma mansoni purified egg antigen for the diagnosis of schistosomiasis in Saudi Arabia.

The enzyme-linked immunosorbent assay (ELISA) using purified Schistosoma mansoni egg antigen (CEF6) was compared with standard parasitological diagnostic tests (potassium hydroxide digestion of faeces and urine filtration) for diagnosis of schistosomiasis in humans in Saudi Arabia. Faecal, urine and finger-prick blood samples were collected from 2 groups of individuals of both sexes, aged 1-50 years, in 2 areas in the western region of Saudi Arabia: 983 in a schistosomiasis endemic area (Al-Hijaz highlands) and 192 in a non-endemic area (Jeddah). In the non-endemic area, almost 90% of the blood samples gave optical density readings at 492 nm (OD) < 0.25. The mean OD in the schistosome endemic area (0.31) was much higher than in the non-endemic area (0.14). The prevalence of S. mansoni infection by faecal examination in the endemic area was 10.2% and the specificity and sensitivity of the ELISA using a cut-off OD of 0.25 were 55% and 90%, respectively. In the endemic area, there was a positive correlation between egg intensity and OD value. No S. haematobium was detected. In the non-endemic area, the specificity was 90%. The main reasons for false positive results may have been inapparent or cured S. mansoni infection.

Adolescent↗