Species of aspergilli are common in man's environment and are responsible for a wide spectrum of human and animal disease, ranging in animals from mycotic abortion to aflatoxicosis and in humans from localized colonization of the ear or skin to life-threatening systemic infection of neutropenic patients. In recent times, invasive aspergillosis has become increasingly important as a cause of morbidity and death, initially in patients receiving immunosuppression prior to organ transplantation, and latterly in haematologic patients rendered neutropenic by underlying disease or chemotherapy. In some centres, the condition has been recorded in more than 40% of patients dying with acute leukaemia. Laboratory diagnostic procedures are not always helpful and the diagnosis depends largely on clinical parameters. The clinician is faced with yet another problem, that of management. At present, antifungal therapy of invasive aspergillosis can be largely ineffectual, and the mortality rate remains unacceptably high. Since Aspergillus fumigatus was first described almost 125 years ago, several other pathogenic species have been recognized. The marked biosynthetic abilities and varied mechanisms of gene recombination of aspergilli have long commanded attention in food technology and genetics. Their equally varied abilities to cause disease have attracted the interest of toxicologists, allergists and physicians concerned with infectious diseases.

Species of aspergilli are common in man's environment and are responsible for a wide spectrum of human and animal disease, ranging in animals from mycotic abortion to aflatoxicosis and in humans from localized colonization of the ear or skin to life-threatening systemic infection of neutropenic patients. In recent times, invasive aspergillosis has become increasingly important as a cause of morbidity and death, initially in patients receiving immunosuppression prior to organ transplantation, and latterly in haematologic patients rendered neutropenic by underlying disease or chemotherapy. In some centres, the condition has been recorded in more than 40% of patients dying with acute leukaemia. Laboratory diagnostic procedures are not always helpful and the diagnosis depends largely on clinical parameters. The clinician is faced with yet another problem, that of management. At present, antifungal therapy of invasive aspergillosis can be largely ineffectual, and the mortality rate remains unacceptably high. Since Aspergillus fumigatus was first described almost 125 years ago, several other pathogenic species have been recognized. The marked biosynthetic abilities and varied mechanisms of gene recombination of aspergilli have long commanded attention in food technology and genetics. Their equally varied abilities to cause disease have attracted the interest of toxicologists, allergists and physicians concerned with infectious diseases.

The World Health Organization estimates that at least five million people worldwide are infected with human immunodeficiency virus (HIV) Of these about 100,000 are in Asia and Oceania, 500,000 in Europe, 2 million in the Americas and 2.5 million in Africa (Mann, 1989). The acquired immunodeficiency syndrome is characterized by a derangement in cell-mediated immunity leading to opportunistic infections with for example Mycobacterium spp., Candida spp., Cryptococcus neoformans, Pneumocystis carinii, Toxoplasma gondii and Cryptosporidium. The third symposium on "Topics in Mycology" brought together 265 experts from 32 countries to discuss the epidemiology, immmunological and pathogenetic aspects of AIDS and its opportunistic infections in general and fungal infections in particular. Pneumocystis carinii pneumonia is by far the commonest opportunistic infection in AIDS patients. The nature and classification of P. carinii is still controversial. In search for its true taxonomic affinities an introductory paper formulates a number of key questions. Candidosis is another frequent opportunistic infection. A number of papers discuss the possibility that selective pressures may operate on Candida albicans within the AIDS population and influence its nature: this might have an impact on prophylaxis and curative and/or suppressive therapy.