Medical Microbiology

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GeneralAspectsofFungalDisease 353

chialasthma,orallergicalveolitis.Manyoftheseallergicreactionsarecerti-
fiedoccupationaldiseases,i.e.,“farmer’slung,”“woodworker’slung,”and
othertypesofextrinsicallergicalveolitis.

Mycotoxicoses


Somefungiproducemycotoxins,thebestknownofwhicharetheaflatoxins
producedbytheAspergillusspecies.Thesetoxinsareingestedwiththefood
stuffsonwhichthefungihavebeengrowing.AflatoxinB1maycontributeto
primaryhepaticcarcinoma,adiseaseobservedfrequentlyinAfricaand
SoutheastAsia.

Mycoses

Dataonthegeneralincidenceofmycoticinfectionscanonlybeapproximate,
sincethereisnorequirementthattheybereportedtothehealthauthorities.
Itcanbeassumedthatcutaneousmycosesareamongthemostfrequentin-
fectionsworldwide.Primaryandopportunisticmycosesare,ontheother
hand,relativelyrare.Opportunisticmycoseshavebeenontheincreaseinre-
centyearsanddecades,reflectingthefactthatclinicalmanifestationsare
onlyobservedinhostswhoseimmunedispositionallowsthemtodevelop.
Increasingnumbersofpatientswithimmunedefectsandahighfrequencyof
invasiveandaggressivemedicaltherapiesarethefactorscontributingtothe
increasingsignificanceofmycoses.Table5. 2 providesasummaryviewofthe
mostimportanthumanmycoses.Thecategorizationoftheinfectionsused
heredisregardstaxonomicconsiderationstoconcentrateonpracticalclinical
aspects.

Host-pathogeninteractions


Thefactorsthatdeterminetheonset,clinicalpicture,severity,andoutcomeof
amycosisincludeinteractionsbetweenfungalpathogenicityfactorsandhost
immunedefensemechanisms.Comparedwiththesituationinthefieldof
bacteriology,itmustbesaidthatwestillknowlittleabouttheunderlying
causesandmechanismsoffungalpathogenicity.
Humansshowhighlevelsofnonspecificresistancetomostfungibasedon
mechanical,humoral,andcellularfactors(seeTable 1. 6 ,p.22).Amongthese
factors,phagocytosisbyneutrophilicgranulocytesandmacrophagesisthe
mostimportant.Intensivecontactwithfungiresultsintheacquisitionofspe-

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Kayser, Medical Microbiology © 2005 Thieme

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