When trying to understand the pathophysiology of any infectious agent, one key piece of information is the determination of its habitat. In the case of Paracoccidioides brasiliensis, the precise location of the fungus' environmental niche remains undefined despite the efforts of various research groups. This review summarizes recent studies on the ecology of P. brasiliensis and certain facets of paracoccidioidomycosis. Studies on the juvenile form of paracoccidioidomycosis in children less than 13 years of age, the characterization of the ecological factors in the 'reservarea' where the infection is acquired and the presence of P. brasiliensis in the nine-banded armadillo (Dasypus novemcinctus), are all helping to pinpoint the microniche of this pathogen. The application of molecular biology techniques based on the amplification of nucleic acids will also hopefully help in establishing the precise habitat of P. brasiliensis.

The habitat of Paracoccidioides brasiliensis: how far from solving the riddle?

The present review is a critical analysis of positive and negative reports of the isolation of Paracoccidioides brasiliensis from soil. The strains isolated from soil or soil-contaminated material (dogfood, penguin feces) by Batista et al. in Recife, Brazil, Negroni in the Argentinian Chaco, Albornoz in rural Venezuela, Silva-Vergara et al. in Ibia, Brazil, Ferreira et al. in Uberlândia, Brazil, and Gezuele et al. at the Uruguayan base in the Antarctic region, presented mycological characteristics consistent with P. brasiliensis. In most of these studies, morphological characterization was complemented with an evaluation of virulence and antigenicity, and biochemical or molecular analysis. These isolations, therefore, can be considered true, supporting the concept of soil as an important element in the ecology of the pathogen. The large number of negative reports in attempts involving soil samples and the low repeatability of isolation of the fungus from the same area indicate that the specific conditions supporting growth of the pathogen in soil have not been fully clarified.

A critical analysis of isolation of Paracoccidioides brasiliensis from soil

Children with the clinical syndrome of visceral larva migrans as a result of Toxocara species have typical lesions in the liver and other viscera, consisting of palisading granulomas that contain numerous eosinophils and often Charcot-Leyden crystals; recognizable parasites are uncommon. Similar eosinophilic granulomas that are found incidentally in adults often cause diagnostic problems. To define better the clinical, laboratory, and pathologic features of these lesions, we reviewed 43 cases of hepatic eosinophilic granuloma (excluding cases of Langerhans' cell histiocytosis) collected in the files of the AFIP over a period of 31 years. The eosinophilic granulomas were found in patients of all ages (range 12 months to 77 years); 30% were younger than 20 years. There were 26 male and 17 female patients. Most patients (26 of 43; 60%) were asymptomatic, and the lesions were discovered incidentally. Others had fever (20%) or abdominal pain (20%). The granulomas were typically multiple (61%), with central necrosis surrounded by a mixed inflammatory infiltrate with numerous eosinophils and variable numbers of neutrophils. lymphocytes, and a palisade of epithelioid histiocytes and/or giant cells. Charcot-Leyden crystals were present in 19 cases (44%). Remnants of parasites (eight Toxocara sp., two Capillaria sp.) were identified in the tissue in 10 patients. There was a positive serologic test for Toxocara sp. in five additional cases. Immunohistochemical staining using polyclonal antiserum against Toxocara canis larvae demonstrated positivity in macrophages in eight of 13 cases tested. We conclude that identification of an eosinophilic granuloma in the liver should suggest the diagnosis of visceral larva migrans and prompt a search for the causative organism with serial sectioning of the block and serologic tests for Toxocara and other causative parasites.

Eosinophilic granuloma of the liver: a characteristic lesion with relationship to visceral larva migrans.

Paracoccidioides brasiliensis has rarely been isolated from its habitat in rural areas. In orderto investigate the hypothesis that human infection with this fungus is linked to coffee plantations (Coffea arabica), material was collected monthly over a period of 1 year from farms in the town of Ibia, State of Minas Gerais, Brazil. A total of 760 samples of soil, coffee leaves and fruits was cultured and inoculated into mice. A fungus isolated from the liver of a mouse inoculated with soil showed temperature-dependent dimorphism and in vitro mycelium and yeast phases characteristic of P. brasiliensis. Yeast cells of this fungus caused disseminated infection after intraperitoneal inoculation in Wistar rats from which the fungus was re-isolated. An antigen reacting with sera from patients with paracoccidioidomycosis was obtained from this P. brasiliensis strain; antigenic identity with strain 339 and with four other P. brasiliensis strains was detected by gel immunodiffusion. However, when the exo-antigen was...

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Isolation of a Paracoccidioides brasiliensis strain from the soil of a coffee plantation in Ibiá, State of Minas Gerais, Brazil

The fungus Paracoccidioides brasiliensis has been isolated from nine-banded armadillos (Dasypus novemcinctus) in different regions where paracoccidiodomycosis (PCM) is endemic. The link between PCM and these animals has provided the first valuable clue in the effort to elucidate the ecological niche of P. brasiliensis. The present study was aimed at correlating P. brasiliensis infection in armadillos with local ecological features and, if possible, the presence of the fungus in the soil in the Botucatu hyperendemic area of PCM. In this region the mean temperature ranges from 14.8 to 25.88C and the annual average precipitation is 1520 mm. The sites where 10 infected animals (positive group) were collected were studied and compared with the sites where five uninfected animals were found. The occurrence of the fungus in soil samples collected from the positive armadillos’ burrows and foraging sites was investigated by the indirect method of animal inoculation. Environmental data from the sites of animal capture, such as temperature, rainfall, altitude, vegetation, soil composition, presence of water and proximity of urban areas, were recorded. All 37 soil samples collected from the sites had negative fungal cultures. Positive animals were found much more frequently in sites with disturbed vegetation, such as riparian forests and artificial Eucalyptus or Pinus forests, in altitudes below 800 m, near water sources. The soil type of the sites of positive animals was mainly sandy, with medium to low concentrations of organic matter. The pH was mainly acidic at all the sites, although the concentrations of aluminum cations (H� /Al) were lower at the sites where positive animals were found. Positive armadillos were also captured in sites very close to urban areas. Our data and previous studies indicate that P. brasiliensis occurs preferentially in humid and shady disturbed forests in a strong association with armadillos.

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High frequency of Paracoccidioides brasiliensis infection in armadillos (Dasypus novemcinctus): an ecological study.

Cuarenta y cinco muestras de tierra, preferentemente de cafetales a mas de 500 m de altitud sobre el nivel del mar, de varias regiones de Venezuela fueron inoculadas por via endovenosa en ratones No pudo aislarse elParacoccidioides brasiliensis Se discuten brevemente las posibles causas de los resultados negativos y se proponen otras technicas para seguir intentando la determinacion del habitat deParacoccidioides brasiliensis

Intento de Aislamiento del Paracoccidioides brasiliensis del suelo

Summary Pulmonary granulomas with adiaspores were found incidentally in two necropsies in which no gross pulmonary lesions existed. Adiaspiromycosis has not previously been described in Venezuela. The literature on this newly identified rare deep mycosis in men is reviewed, and the importance of early diagnosis is emphasized, suggesting a lowered threshold of suspicion when granulomas are found.

Two cases of adiaspiromycosis.

Summary Ninety-six specimens of liver, appendix, ileum, and other viscera with eosinophilic granulomas were studied at autopsy and in surgical tissue preparations from a tropical country. Since there was no evidence that these granulomas were due to allergy or to parasites, they are assumed to have been produced by microfilariae (larva migrans, visceral) and it is proposed to call the entity visceral eosinophilic granulomas.

M. de Mendelovici

Papers

Intento de Aislamiento del Paracoccidioides brasiliensis del suelo

Two cases of adiaspiromycosis.

Visceral Eosinophilic Granulomas