Meiotic chromosomes and sex determination mechanism in Thailand and Hawaii isolates of Angiostrongylus cantonensis (Nematoda: Angiostrongylidae).

Angiostrongylus cantonensis, the nematode lungworm of rats, has a XX/X0 sex-determination mechanism. The chromosome constitution consists of 10 autosomes, with 2n=12, XX in the female and 2n=11, X0 in the male. Meiosis-I shows five bivalents and one univalent for the male worm, and six bivalents for the female worm. The chromosome constitution of the Thailand and Hawaii isolates of A. cantonensis is similar to those reported for the taxa from Japan, Egypt and mainland China.

Isolated optic neuritis from an identified Gnathostoma spinigerum.

PURPOSE: To describe a patient with isolated monocular optic neuritis caused by an identified Gnathostoma spinigerum infestation. CASE REPORT: A 21-year-old man developed a swollen eyelid and painful monocular visual loss of his left eye which did not improve after treatment by intravenous steroid and albendazole. A remarkable eosinophilia in his peripheral blood count was demonstrated. The patient subsequently found a live parasite emerged from his lower eyelid and it was successfully removed by himself. Gross and histopathology examinations of the obtained parasite was undertaken. The parasite was identified as Gnathostoma spinigerum. His blood test for Gnathostoma antibody was positive. DISCUSSION: The etiology of isolated optic neuritis in this patient was Gnathostoma spinigerum which was confirmed by the histopathology of the obtained parasite and the positive serologic test. CONCLUSIONS: We could identify the exact parasite that was proven to cause an isolated optic neuritis. The immediate removal of a causative parasite maynot result in an improvement of the injured tissue but is beneficial in preventing further destruction as well as future complications.

Multi-immunodot for rapid differential diagnosis of eosinophilic meningitis due to parasitic infections.

A multi-dot enzyme-linked immunosorbent assay (ELISA) was developed for the rapid and simple differential diagnosis of eosinophilic meningitis due to helminth infections. Ultrafiltered, purified antigens of Parastrongylus (=Angiostrongylus) cantonensis, Gnathostoma spinigerum and Taenia solium metacestodes, the most common parasites that invade the central nervous system and cause eosinophilic pleocytosis, were dotted onto a single nitrocellulose membrane strip. Antigen-coated strips, when blocked with 5% skimmed milk and dried, were stable for at least 6 months at 4 degrees C. With peroxidase conjugated anti-human immunoglobulins and 4-chloro-1-naphthol as a substrate, antibodies in the corresponding patients' sera were clearly detected on the membrane strip as well-defined blue dots. Although cross-reactions between P. cantonensis and G. spinigerum antigens were observed with the use of partially purified antigens, the darkest dot correlated well with the infecting parasites in all cases. This fast, easy and economical multiple dot-blot ELISA method is useful for the differential diagnosis of eosinophilic meningitis caused by parasitic helminths, as semi-purified antigens can be easily obtained by ultrafiltration and used. Further improvements using highly specific parasite antigens may make this multi-immunodot test more suitable for wide-scale use in field studies and diagnostic laboratories.

A dot-blot ELISA comparable to immunoblot for the specific diagnosis of human parastrongyliasis.

A dot-blot enzyme-linked immunosorbent assay (dot-blot ELISA) using an electroeluted 31-kDa glycoprotein from adult worms of Parastrongylus cantonensis as the specific antigen was evaluated for the immunological diagnosis of patients infected with P. cantonensis. The sensitivity and specificity for the detection of serum antibody to P. cantonensis in dot-blot ELISA were both 100%, as determined with serum samples of ten P. cantonensis-infected patients, 60 patients with other related parasitic infections, and 20 uninfected controls. The test was as sensitive and specific as the immunoblot test which revealed a reactive band of 31 kDa. Both the dot-blot ELISA and immunoblot detected all sera from ten P. cantonensis-infected individuals, but not with those of other heterologous parasitoses (gnathostomiasis, toxocariasis, filariasis, paragonimiasis, cysticercosis and malaria) or sera from healthy controls. The dot-blot ELISA is much simpler to perform than the immunoblot technique, and the test can be applied under field conditions where sophisticated facilities are lacking.

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.

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.