Phase 2 trial of WR6026, an orally administered 8-aminoquinoline, in the treatment of visceral leishmaniasis caused by Leishmania chagasi.

There are no recognized orally administered treatments for any of the leishmaniases. The 8-aminoquinoline WR6026 is an orally administered analog of primaquine that cured 50% of patients with kala-azar in Kenya at a dose of 1 mg/kg/day for 28 days. A further phase 2, open-label, dose-escalating safety and efficacy study was performed for kala-azar in Brazil. Cure rates for Brazilian patients treated for 28 days were as follows: 1 mg/kg/day: 0 of 4 (0%); 1.5 mg/kg/day: 1 of 6 (17%); 2.0 mg/kg/day: 4 of 6 (67%); 2.5 mg/kg/day: 1 of 5 (20%); and 3.25 mg/kg/day: 0 of 1 (0%). Nephrotoxicity that was not anticipated from preclinical animal studies or from phase 1 studies was seen at 2.5 mg/kg/day in 2 patients and in the single patient administered 3.25 mg/kg/day. WR6026 demonstrated the unusual clinical features of lack of increased efficacy against Brazilian kala-azar with increased dosing above 2 mg/kg/day and toxicity that was not present in previous investigations.

Schistosomiasis mansoni: immunoblot analysis to diagnose and differentiate recent and chronic infection.

One hundred seven patients classified into three different groups (11 with acute schistosomiasis, 58 with chronic schistosomiasis, and 38 children with high IgM-specific antibody titers against schistosome gut-associated antigens living in an endemic schistosomiasis area) were studied by immunoblotting for the presence of IgG, IgM, and IgA antibodies against Schistosoma mansoni soluble adult worm antigen preparation. We used sera from 15 individuals infected with various intestinal parasites, as well as sera from 19 uninfected individuals, as controls. An immunogenic fraction with a molecular weight of 31-32 kD (Sm31/32) was the most frequently recognized by the different antibody isotypes. In the group with acute disease, this fraction was recognized by IgG and IgM antibodies of all patients, and by 10 (90.9%) of 11 samples for IgA antibodies. Approximately 98% of the patients with chronic infections had IgG antibodies against Sm31/32, but only about 10% had IgM and IgA antibodies against this fraction. The IgG immunoblot profiles of the children from the endemic area were similar to those obtained for the group with acute schistosomiasis. This observation suggests recent infection of these children. Our data show that the Sm31/32 protein fraction is highly immunogenic and may be a useful serologic marker for diagnosing and differentiating between acute and chronic schistosomiasis infection.

Humoral immune responses among mucosal and cutaneous leishmaniasis patients caused by Leishmania braziliensis.

Mucosal leishmaniasis is arguably the most morbid sequelae of cutaneous leishmaniasis. The importance of early diagnosis for effective therapy, coupled with the difficulty of diagnosing the disease parasitologically, prompted this investigation of humoral immune markers of mucosal disease. Promastigote soluble antigens of Leishmania braziliensis, isolated from cutaneous and mucosal lesions, were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis; antigens were identified by immunoblotting with parasite-specific IgG antibody-positive sera of patients with mucosal disease (n = 18) and cutaneous disease (n = 23). For antigens of the cutaneous parasite WR 2095, mucosal sera generally reacted intensely to antigens of 75, 66, and 45 kDa and weakly to 48-50-kDa antigens, whereas cutaneous sera generally detected weakly the first 3 antigens and intensely the latter doublet. The data suggest that the transition from the cutaneous antigenic profile to a mucosal antigenic profile could be used to predict mucosal disease in approximately half of mucosal patients. An additional finding was that antibodies present in the sera of patients with mucosal disease labeled a 66-kDa peptide of normal human lip mucosa more intensely than did cutaneous sera. Autoimmune processes stimulated by the reaction of IgG, originally directed against the 66-kDa of L. braziliensis, to the 66-kDa antigen of mucosal tissue may contribute to the clinical presentation of mucosal leishmaniasis.

Efficacy of an enzyme-linked immunosorbent assay in the diagnosis of and serologic distinction between acute and chronic Schistosoma mansoni infection.

To determine the efficacy of an ELISA to diagnose and differentiate the clinical phases of schistosomiasis, serum from patients with acute (11) and chronic schistosomiasis (58), from individuals infected with other parasites (53), and from uninfected individuals (40) was analyzed for the presence of anti-schistosomal of IgG, IgM, and IgA antibodies. Immunofluorescence for IgM and IgA antibodies was also performed on serum from all patients and controls. The IgG antibodies against worm antigen (ELISA-w) were detected in all schistosomiasis patients, with only one false-positive result. The IgA antibodies were detected by ELISA-w in 81.8% of patients with acute disease and in only 5.9% of patients with chronic disease. In addition, the mean optical density values for IgM and IgA antibodies was statistically higher in the patients with acute disease than in those with chronic disease. The results of this study show that the use of a crude adult worm extract as an ELISA antigen can provide a serologic method with high sensitivity and specificity for 1) the diagnosis of acute and chronic schistosomiasis and (2) the serologic distinction between the two forms of the disease.

Diagnosis of canine visceral leishmaniasis with a dot-enzyme-linked immunosorbent assay.

The maintenance and transmission of human visceral leishmaniasis in an endemic area usually requires a mammalian reservoir. Though universal reservoir elimination has previously been effective in controlling this disease in countries where the primary reservoir is the dog, selective elimination would be preferable. To guide this selection process, we performed a prospective, single, blind, cohort study evaluating the dot-enzyme-linked immunosorbent assay (dot-ELISA) in 130 canines from both endemic and nonendemic areas. The results were compared with blinded bone marrow aspirate examination and physical assessment of the animals. Using visualization of amastigotes on bone marrow examination as a priori evidence of infection, the dot-ELISA was found to be highly sensitive (97%) and specific (100%). In contrast, the physical evaluation had remarkably low sensitivity and specificity. The dot-ELISA is an excellent test for detection of the canine reservoir of Leishmania. Because it is simple to perform, inexpensive, and highly accurate, it may help control this debilitating illness by facilitating selective canine elimination.