Here, we report, to our knowledge, the largest case study of human pythiosis. The disease has high rates of morbidity and mortality. Early diagnosis and effective treatment are urgently needed to improve clinical outcomes. Because P. insidiosum is distributed worldwide and can infect healthy individuals, an awareness of human pythiosis should be promoted in Thailand and in other countries.

From June 1990 to August 1991, 21 patients infected with the human immunodeficiency virus (HIV) presented with systemic mycosis caused by Penicillium marneffei. Between August 1987 and August 1991, only five patients were observed who had P. marneffei infection but not HIV infection. The clinical presentation included fever, cough, and generalized papular skin lesions. For 11 of these 21 patients, the presumptive diagnosis of P. marneffei infection could be made by microscopic examination of Wright's-stained bone marrow aspirate and/or touch smears of skin specimens obtained by biopsy several days before the results of culture were available. Initial clinical response to treatment with either parenteral amphotericin B or oral itraconazole was favorable in most patients. Epidemiological and clinical evidence suggest that this systemic mycosis is caused by an important opportunistic pathogen and that it should be included in the differential diagnosis of AIDS, at least for countries in areas of endemicity, i.e., Southeast Asia and China.

Pythium insidiosum is a pathogen that causes disease in both animals and humans. Human infection is rare; however, when it does occur, most patients, especially those having underlying hemoglobinopathy syndromes, such as thalassemia, exhibit a severe form. We identified four isolates of P. insidiosum. Two were recovered from tissue biopsy specimens from thalassemic and leukemic patients, one was derived from brain tissue from a thalassemic patient, and another was isolated from a corneal ulcer from a fourth patient. Western blotting and an enzyme-linked immunosorbent assay (ELISA) were performed with a serum sample derived from one thalassemic patient. The methods used to identify the P. insidiosum isolates were based on morphology, nucleic acid sequencing, and a PCR assay. To confirm the identification, portions of the 18S rRNA genes of these four isolates were sequenced. The sequences were shown to be homologous to previously described P. insidiosum DNA sequences. In addition, PCR amplification of the internal transcribed spacer region specific for P. insidiosum was positive for all four isolates. The ELISA with the serum sample from the thalassemic patient gave a positive result from a serum dilution of 1:800. Finally, Western immunoblotting with this serum sample showed positive immunoglobulin G recognition for proteins of 110, 73, 56, 42 to 35, 30 to 28, 26, and 23 kDa. The results of this study show that both molecularly based diagnostic and serodiagnostic techniques are useful for the rapid identification of human pythiosis. The predominant antigens recognized by Western blotting may be useful in the development of a more sensitive and specific diagnostic tool for this disease.

SummaryBackground Leishmaniasis is a newly emerging infection in Thailand. Most of the previous human cases have presented with the clinical features of visceral leishmaniasis and were mainly found in southern Thailand. Here we report the first two patients from northern Thailand presenting with disseminated cutaneous leishmaniasis. Objectives To determine the nature of the infection of leishmaniasis and to identify the species of parasite responsible. Methods Clinical investigations included the taking of biopsy samples and histology. Parasitological diagnosis was performed by establishment of Leishmania promastigote cultures, and identification was performed by DNA sequencing of four independent gene loci (ribosomal RNA internal transcribed spacer 1; large subunit of RNA polymerase II; heat shock protein 70; RPL23a intergenic sequence). Results Both patients were infected with HIV, and had multiple cutaneous lesions and accompanying visceral leishmaniasis. They had similar cutaneous manifestations characterized by chronic generalized fibrotic lesions, which were more prominent on traumatic areas. In both patients the parasite was identified as Leishmania martiniquensis. This is a recently described species that is distinct and only distantly related to the classical agents of cutaneous leishmaniasis in Asia (Leishmania major and Leishmania tropica) or of visceral leishmaniasis (Leishmania donovani and Leishmania infantum). Each patient responded well to therapy with intravenous amphotericin B followed by oral itraconazole. Conclusions Leishmania martiniquensis is a cause of cutaneous leishmaniasis in Thailand.