Purification of a specific immunodiagnostic Parastrongylus cantonensis antigen by electroelution from SDS-polyacrylamide gels.

A 31-kDa glycoprotein antigen was purified by electrophoresing the crude extract of Parastrongylus cantonensis adult worms in a 12% SDS-polyacrylamide gel, identifying the 31-kDa component with prestained molecular weight standards, cutting the desired gel strip, and then isolating it by electroelution. Antigen fraction of 31 kDa was re-electrophoresed, transferred to a nitrocellulose membrane and found to be reactive with only the sera from patients with parastrongyliasis. No reactive band was observed with the sera from other related parasitic infections, eg, gnathostomiasis, toxocariasis, filariasis, paragonimiasis, cysticercosis and malaria, and the normal healthy control sera. This antigen fraction isolated showed 100% sensitivity and 100% specificity in the enzyme-linked immunosorbent assay (ELISA) for the detection of 31-kDa specific antibody in the sera from patients with parastrongyliasis. The P. cantonensis antigen of 31 kDa has been obtained by this means with a high degree of purity and applied successfully in conventional ELISA for the specific immunodiagnosis of human parastrongyliasis.

Prevalence of parasitic infections in Thai workers from 1993 to 1997.

Study on the prevalence of parasitic infections in Thai laborers who applied for working abroad was carried out during 5 years. The total number of 78,240 stool specimens was obtained and examined by simple smear and iodine. It was found that the prevalence of parasitic infections from 1993 to 1997 was 12.15%, 13.13%, 12.57%, 4.62% and 5.76% respectively. The five most frequently parasites found in stool were Blastocystis hominis, hookworms, Giardia lamblia, Strongyloides stercoralis and Opisthorchis viverrini. Such findings were similar to previous reports, but in lower percentages. Thus, continuity of public health education and sanitation improvement should be concerned for prevention and control of parasitic infections.

High prevalence of Cryptosporidium in young children with prolonged diarrhea.

A prospective study was done to identify Cryptosporidium in the stools of young children, aged 2 months to 3 years, admitted to hospital. Of a total of 387 stool samples from 387 individuals, 131 stool specimens forming the control group were from children with non-diarrheal, respiratory tract infections, 200 and 56 stool samples were from children with acute diarrhea and prolonged diarrhea, respectively. No Cryptosporidium was discovered in the control group. Only 1 sample positive for Cryptosporidium was found in the group with acute diarrhea, whereas 4 samples of Cryptosporidium were found in the group with prolonged diarrhea. The prevalence of Cryptosporidium in the group with prolonged diarrhea was significantly higher than the other two groups (p < 0.05). In those children with prolonged diarrhea, Cryptosporidium should always be included in the differential diagnosis.