Novel and challenging infections of man. A brief overview.

The greatest challenge to human health of recent times is the pandemic caused by the retroviruses known as HIV1 and HIV2. These have unleashed a plethora of opportunistic infections with organisms ranging from other viruses to helminths, some of which are newly recognised taxa or organisms never before identified as serious pathogens of man. Animal and bird migration as well as human travel and international trade have extended, to an alarming degree, the dissemination of other viral infections. Malaria is an increasing global challenge to human health, a reversal of the downward trend that was achieved in the latter half of the 20th century. Moreover, evidence is currently accumulating for the existence of a fifth species of Plasmodium in man. In the bacterial and protozoal fields, other novel organisms are being described. Powerful new tools of molecular biology are being deployed to probe parasite genetics, for example to reveal the genome of Plasmodium falciparum. These and molecular immunological techniques are also helping to resolve puzzling taxonomic questions, as well as aiding epidemiological studies that are revealing the unforeseen scale of human infection with a number of parasitic helminths in both tropic and temperate climatic areas. This paper presents a brief review of the major, as well as some of the relatively minor changes and advances of recent decades.