Human Pythiosis Research Articles

Vascular pythiosis in a thalassemic patient presenting as bilateral leg ulcers

Human pythiosis is an emerging disease caused by Pythium insidiosum, a fungus-like aquatic organism. Clinical presentations can be classified into four types: (i) cutaneous/subcutaneous, (ii) ocular, (iii) vascular, and (iv) disseminated pythiosis. Serological tests such as immunodiffusion and immunochromotographic test are useful to make rapid diagnosis in cutaneous and vascular pythiosis. We report a case of 35 year-old male with vascular pythiosis of both legs, diagnosed by serology and molecular techniques.

Necrotizing arteritis due to emergingpythium insidiosumInfection in patients with thalassemia: Rapid diagnosis with pcr and serological tests — Case reports

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.

Pythium insidiosum Keratitis in Israel

To report with morphologic and phylogenetic speciation the first case from Israel of Pythium insidiosum keratitis associated with contact-lens wear. Case report and literature review. A 21-year-old man with a history of contact-lens use and water exposure was hospitalized in Israel for a corneal ulcer. The ulcer progressed despite intensive antibiotics. He flew home to the United States for further care. Examination revealed a corneal ulcer with hypopyon. The infection progressed despite intensive medical therapy, and a therapeutic penetrating keratoplasty was performed. Histology and cornea cultures from the host cornea revealed sparsely septate, branching hyphae, consistent with P. insidiosum. DNA sequencing of the Pythium isolate supported the clinical history that the infection was acquired outside of the United States. Despite intensive medical therapy and a second corneal transplant, the ulcer progressed, ultimately requiring enucleation. This is the first reported case of culture-proven, contact lens-related Pythium keratitis originating from Israel. Pythium is a fungus-like, aquatic oomycete found in tropical climates. Human pythiosis is uncommon but associated with high morbidity. Case reports describe surgical cure of Pythium keratitis, but this case recurred despite two penetrating keratoplasties and maximal antifungal therapy. In cases of presumed fungal keratitis that do not respond to antifungals, the fungus should be sent for speciation because early surgical intervention is the only means to save the eye in ocular pythiosis.

Successful treatment of a child with vascular pythiosis

BackgroundHuman pythiosis is an emerging and life-threatening infectious disease caused by Pythium insidiosum. It occurs primarily in tropical, subtropical and temperate areas of the world, including Thailand. The aim of this report is to present the first pediatric case of typical vascular pythiosis.Case PresentationA 10-year-old boy with underlying β-thalassemia presented with gangrenous ulcers and claudication of the right leg which were unresponsive to antibiotic therapy for 6 weeks. Computerized tomography angiography indicated chronic arterial occlusion involving the right distal external iliac artery and its branches. High-above-knee amputation was urgently done to remove infected arteries and tissues, and to stop disease progression. Antibody to P. insidiosum was detected in a serum sample by the immunoblot and the immunochromatography tests. Fungal culture followed by nucleic sequence analysis was positive for P. insidiosum in the resected iliac arterial tissue. Immunotherapeutic vaccine and antifungal agents were administered. The patient remained well and was discharged after 2 months hospitalization without recurrence of the disease. At the time of this communication he has been symptom-free for 2 years.ConclusionsThe child presented with the classical manifestations of vascular pythiosis as seen in adult cases. However, because pediatricians were unfamiliar with the disease, diagnosis and surgical treatment were delayed. Both early diagnosis and appropriate surgical and medical treatments are crucial for good prognosis.

Vascular Pythiosis in a Thalassemic Patient

Pythium insidiosum is a fungus that causes disease in both animals and humans. Human pythiosis is an emerging disease in the tropical, subtropical, and temperate regions of the world, occurring in localized and systemic or vascular forms. Most patients with arterial pythiosis have an underlying hemoglobinopathy, such as thalassemia. A case is presented of a thalassemic horse stable worker who developed an ulcerative cutaneous lesion on the lower left leg followed by progressive ascending involvement of the arteries of that extremity with a necrotizing arteritis with aneurysm formation. P. insidiosum was not isolated from the ulcer by culture or wet potassium hydroxide preparations but was diagnosed by histopathologic study of a biopsy. P. insidiosum infection was quickly confirmed by immunoblot method, aiding in preoperative decision making. Many systemic antibiotics or antimycotics have not been effective in the treatment of systemic pythiosis, and radical surgical removal of all infected tissue is the only method to ensure patient survival. An orally administered saturated solution of potassium iodide, amphotericin B-oral solution, and terbinafine has succeeded only in the cutaneous form but had no favorable effect on vascular pythiosis. It is likely that immunotherapy, successfully used in animal pythiosis, may be beneficial in the treatment of human vascular pythiosis.

Hemagglutination Test for Rapid Serodiagnosis of Human Pythiosis

Human pythiosis is an emerging, life-threatening infectious disease, caused by the oomycete Pythium insidiosum. Thailand is an area where human pythiosis is endemic and the genetic blood disorder thalassemia is a predisposing factor. Patients with pythiosis present with arterial occlusions of the lower extremities, corneal ulcers, or chronic cutaneous infections. Diagnosis relies on time-consuming, relatively insensitive tests such as culture identification and immunodiffusion assay. Most patients undergo surgical removal of infected organs, and many die from the infection. Delayed diagnosis results in a poor prognosis. Here, we describe a hemagglutination (HA) test for rapid diagnosis of human pythiosis. Sheep red blood cells were coated with P. insidiosum protein extract and used in duplicated detection assays using serum samples from 33 patients with vascular (n = 27), cutaneous (n = 2), or ocular (n = 4) pythiosis and serum samples from 289 control patients with other infectious diseases (n = 77), with highly positive antinuclear antibody (n = 5), with thalassemia (n = 21), or with no known disorder (i.e., healthy blood donors) (n = 186). Based on receiver-operating characteristic analysis, a serum titer of 1:160 was selected as the cutoff point for the HA test. Serum samples that generated HA at the cutoff titer were read as positive, while samples that did not were read as negative. Positive results were obtained with the serum samples of all patients with vascular and cutaneous pythiosis and with two serum samples from the control group. Negative results were obtained with serum samples from all ocular pythiosis patients and the 287 remaining serum samples from the control group. Sensitivity and specificity of the HA were 88% and 99%, respectively. In conclusion, the HA test for detection of anti-Pythium antibodies is a simple, rapid, and reliable test for serodiagnosis of vascular and cutaneous pythiosis.

Development of an Immunochromatographic Test for Rapid Serodiagnosis of Human Pythiosis

Human pythiosis is an emerging and life-threatening infectious disease caused by the fungus-like organism Pythium insidiosum. High rates of morbidity and mortality for patients with pythiosis are exacerbated by the lack of early diagnosis and an effective treatment. Here, we developed and evaluated an immunochromatographic test (ICT) for the diagnosis of human pythiosis, in comparison to a standard serological test of immunodiffusion (ID). Culture filtrate antigen of P. insidiosum was used to detect human anti-P. insidiosum antibody. Sheep anti-human immunoglobulin G-colloidal gold conjugate was used to generate an ICT signal. Thirty-three sera from patients with vascular (n = 27), ocular (n = 4), and cutaneous (n = 2) pythiosis and 181 control sera from healthy blood donors (n = 100), as well as patients with a variety of infectious (n = 56) and noninfectious (n = 25) diseases, were included in the test evaluation. The turnaround time for generating a result by the ICT was less than 30 min, while that for ID was approximately 24 h. Based on the results for all sera of pythiosis patients and the control groups, the ICT showed 88% sensitivity and 100% specificity and ID showed 61% sensitivity and 100% specificity. By both tests, false-negative results for sera from all ocular pythiosis patients were obtained. In addition, the ID test yielded false-negative results for sera from eight patients with vascular pythiosis and one patient with cutaneous pythiosis. It was concluded that the ICT is a rapid, user-friendly, and reliable serological test for the early diagnosis of vascular and cutaneous pythiosis.

Pythium insidiosum Thai isolates: molecular phylogenetic analysis

Background: Pythium insidiosum is an oomycete that infects both humans and animals, leading to a life-threatening infectious disease called “pythiosis”. Animal pythiosis presents with lesions of the skin, gastrointestinal tract, lung and bone, whereas human pythiosis presents with two common clinical forms, vascular pythiosis involving arteries, and ocular pythiosis involving the eye. Pythiosis in humans has been reported exclusively from Thailand. The disease in animals has been found around the world, but its occurrence has never been reported from Thailand. Objective: To group P. insidiosum based on molecular phylogenetic analysis, investigating correlation between phylogenetic group, geographic distribution, and host specificity of this pathogen. Methods: 113 rDNA internal transcribed spacer sequences of P. insidiosum were also obtained for phylogenetic analyses. These included 32 human isolates and 59 environmental isolates from Thailand, and four additional human isolates and 18 animal isolates from around the world. Results: P. insidiosum existed in three distinct clades in accordance with geographic distribution; clade-I contained American isolates, clade-II contained Asian and Australian isolates, and clade-III contained mainly Thai isolates. The Thai isolates existed only in clade-II and clade-III. Conclusion: There were two major subpopulations of P. insidiosum in Thailand. There were no correlation between the two Thai subpopulations of P. insidiosum and geographic regions or host specificity.

Clinical and Epidemiological Analyses of Human Pythiosis in Thailand

Pythiosis is an emerging and life-threatening infectious disease in humans and animals that is caused by the pathogenic oomycete Pythium insidiosum. Human pythiosis is found mostly in Thailand, although disease in animals has been increasingly reported worldwide. Clinical information on human pythiosis is limited, and health care professionals are unfamiliar with the disease, leading to underdiagnosis, delayed treatment, and poor prognosis. To retrospectively study the clinical and epidemiological features of human pythiosis, we analyzed clinical data from patients with pythiosis diagnosed during the period of January 1985 through June 2003 at 9 tertiary care hospitals throughout Thailand. A total of 102 cases of human pythiosis were documented nationwide. A substantial proportion (40%) of cases occurred in the last 4 years of the 18-year study interval. Clinical presentations fell into 4 groups: cutaneous/subcutaneous cases (5% of cases), vascular cases (59%), ocular cases (33%), and disseminated cases (3%). Almost all patients with cutaneous/subcutaneous, vascular, and disseminated pythiosis (85%) had underlying thalassemia-hemoglobinopathy syndrome. Most ocular cases (84%) were associated with no underlying disease. A majority of the patients were male (71%), were aged 20-60 years (86%), and reported an agricultural occupation (75%). Regarding treatment outcomes, all patients with disseminated infection died; 78% of patients with vascular disease required limb amputation, and 40% of these patients died; and 79% of patients with ocular pythiosis required enucleation/evisceration. 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.

Human Pythiosis

Human Pythiosis

Necrotizing arteritis due to emergingpythium insidiosumInfection in patients with thalassemia: Rapid diagnosis with pcr and serological tests — Case reports

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.

Human Pythiosis, Brazil

Pythiosis, caused by Pythium insidiosum, occurs in humans and animals and is acquired from aquatic environments that harbor the emerging pathogen. Diagnosis is difficult because clinical and histopathologic features are not pathognomonic. We report the first human case of pythiosis from Brazil, diagnosed by using culture and rDNA sequencing.

Identification of emerging human-pathogenic Pythium insidiosum by serological and molecular assay-based methods.

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.

Efficacy of immunotherapy using antigens of Pythium insidiosum in the treatment of vascular pythiosis in humans

Human pythiosis is an emerging disease in the tropical, subtropical and temperate regions of the world. It is caused by the straminipilan, fungus-like, aquatic organism Pythium insidiosum. Pythiosis occurs in localized as well as systemic or vascular forms. Most patients with arterial pythiosis usually have underlying hematologic disorders such as thalassemia and aplastic anemia/paroxysmal nocturnal hemoglobinuria (PNH) syndrome. Vascular pythiosis is characterized by ascending blood vessel infections and thrombosis of the major arteries especially those of the lower extremities. When the infection reaches a main artery, the patient usually dies within weeks. Since this pathogen is resistant to most antifungal drugs, immunotherapy was recently used to cure humans and animals with the disease. A modified P. insidiosum-antigen (PIA) formulation had already saved a young boy with life-threatening arterial pythiosis. Here, we report the therapeutic benefits of the PIA in eight patients with vascular pythiosis. Six of them had thalassemia and the other two had PNH. All of the patients had arterial occlusion of the lower limbs. P. insidiosum was isolated and identified by culture and by histopathology. All patients had evidence of active infection when immunotherapy began. After two injections of 100–200 μl of PIA (2.0 mg/ml), at a 14-day interval, four patients (50%) had dramatic and complete remission. Two patients showed partial responses to PIA while the other two did not. Clinical responses correlated with the immunological reactions at the site of injection, clearance of the arteries and cytokine production. The latter included the shifting in serum levels of IL4 and IL5 to IL2 suggesting a switching from a T helper 2 (Th2) to a T helper 1 (Th1) subset. Our findings provide further evidence that immunotherapy using PIA is a safe and effective method to treat pythiosis in humans.

Human pythiosis in Thailand

Pythium insidiosum is a protoctista and causes diseases in plants and animals. In Thailand it can cause a unique human infection of three types. The first type is a subcutaneous lesion in thalassaemic patients, with the pathological findings of a granulomatous reaction, diffuse infiltration, and oedema of the vessel walls. The patients responded to a saturated solution of potassium iodide. The second type is chronic inflammation and occlusion of blood vessels mainly in the lower extremities which results in gangrene or aneurysm formation. This type of infection is only found in thalassaemic patients and leads to amputation of the affected extremities or resection of the involved arteries. The third type is keratitis. This type of infection may or may not be associated with thalassaemia. The clinical signs and symptoms do not differentiate it from other types of myocotic keratitis. The patients end up with keratoplasty, evisceration or enucleation. Thailand is an agricultural country, and there are plenty of swampy areas and several plants to support the life cycle of Pythium. Moreover, many people suffer from thalassaemia, and there is no drug available for Pythium. Pythiosis plays an important role in medicine in Thailand.

Immunodiffusion test for diagnosis and monitoring of human pythiosis insidiosi

To facilitate the laboratory diagnosis of human cases of pythiosis insidiosi, an immunological test was evaluated. A soluble antigen was prepared from a human isolate of Pythium insidiosum, an aquatic, thermotolerant oomycete that causes infections in cattle, dogs, horses, and humans. Sera from seven proven cases of disseminated human pythiosis insidiosi were tested in an immunodiffusion test along with appropriate control sera from patients with a variety of actinomycotic, bacterial, and mycotic diseases as well as sera from uninfected individuals. Titers ranged from 1:1 to 1:32 in the seven serum samples from the disseminated cases of pythiosis insidiosi of varying severity. The heterologous sera gave negative reactions. The rapidity and specificity of the immunodiffusion test makes it a useful diagnostic tool for the serodiagnosis of P. insidiosum infections.

Immunodiffusion test for diagnosing human pythiosis

An immunodiffusion test was developed for diagnosing subcutaneous and systemic pythiosis in humans. When culture filtrate antigen (CFA) from P. insidiosum was reacted against patient and rabbit antisera, 1-5 precipitin bands occurred both in patient and rabbit antisera, and a line of identity also occurred between patient and rabbit sera. When control P. insidiosum CFA was reacted with 30 apparently normal persons, 20 Thalassemia patients, 2 candidosis and 5 aspergillosis patients, no precipitin bands were found. P. insidiosum CFA also tested with rabbit antibodies to B. dermatitidis, C. immitis, H. capsulatum, P. brasiliensis, C. albicans, M. furfur and A. fumigatus revealed no cross reactions. This test is practical, sensitive and specific.