Abstract
Pythium insidiosum is a pathogen that causes disease in both animals and humans. Human pythiosis is
an emerging disease in the tropical, subtropical, and temperate regions of the world.
Pythiosis occurs in localized and systemic or vascular forms. Most patients with arterial
pythiosis have underlying hemoglobinopathy syndromes such as thalassemia, which exhibits
a severe form. We present a series of eight cases of emerging human vascular pythiosis
in northern Thailand and confirm that PCR and Immunoassay can make an early and accuracy
diagnosis of vascular pythiosis. Prospective studies were made during a 38-month period
from July 2001 to December 2004 of eight hemoglobinopathic patients with a distinct
clinical syndrome characterized by progressive ischemia of the lower extremities,
with ascending arteritis and aneurysm formation. One patient died when infection caused
bifurcation of the aorta with arterial leakage before diagnosis and treatment. One
patient refused any treatment and was lost to followup. All eight patients worked
in wet and swampy areas (7 farmers and 1 horse stable worker). Pythium insidiosum was isolated from three patients and histopathologically diagnosed in five patients.
Wet KOH preparation could identify nonseptate hyphae in only three patients. Rapid
identification of Pythium insidiosum by immunoblot and PCR methods can provide diagnosis and management. There are no
effective antimicrobial agents for this syndrome; radical surgical removal of infected
tissue is the only way to ensure survival of the patient. Immunotherapy using P. insidiosum antigen (PIA) may be effective in treating human pythiosis. P. insidiosum infection should be considered in thalassemic patients with leg ulcer and arterial
occlusion of the lower extremities.
