Zygomycosis

Zygomycosis is the broadest term to refer to infections caused by bread mold fungi of the zygomycota phylum. However, because zygomycota has been identified as polyphyletic, and is not included in modern fungal classification systems, the diseases that Zygomycosis can refer to are better called by their specific names: mucormycosis (after Mucorales), phycomycosis (after Phycomycetes) and basidiobolomycosis (after Basidiobolus). These rare yet serious and potentially life-threatening fungal infections, usually affect the face or oropharyngeal (nose/mouth) cavity. Zygomycosis type infections are most often caused by common fungi found in soil and decaying vegetation. While most individuals are exposed to the fungi on a regular basis, those with immune disorders (immunocompromised) are more prone to fungal infection. These types of infections are also common after natural disasters, such as tornadoes or earthquakes, where people have open wounds that have become filled with soil or vegetative matter.

The condition may affect the gastrointestinal tract or the skin. In non-trauma cases, it usually begins in the nose and paranasal sinuses and is one of the most rapidly spreading fungal infections in humans. Common symptoms include thrombosis and tissue necrosis. Treatment consists of prompt and intensive antifungal drug therapy and surgery to remove the infected tissue. The prognosis varies vastly depending upon an individual patient's circumstances.

Causes

Pathogenic Zygomycosis is caused by species in two orders: Mucorales or Entomophthorales, with the former causing far more disease than the latter. These diseases are known as "mucormycosis" and "entomophthoramycosis", respectively.

• Order Mucorales (mucormycosis)
  • Family Mucoraceae
    • Absidia (Absidia corymbifera)
    • Apophysomyces (Apophysomyces elegans and Apophysomyces trapeziformis)
    • Mucor (Mucor indicus)
    • Rhizomucor (Rhizomucor pusillus)
    • Rhizopus (Rhizopus oryzae)
  • Family Cunninghamellaceae
    • Cunninghamella (Cunninghamella bertholletiae)
  • Family Thamnidiaceae
    • Cokeromyces (Cokeromyces recurvatus)
  • Family Saksenaeaceae
    • Saksenaea (Saksenaea vasiformis)
  • Family Syncephalastraceae
    • Syncephalastrum (Syncephalastrum racemosum)

• Order Entomophthorales (entomophthoramycosis)
  • Family Basidiobolaceae
    • Basidiobolus (Basidiobolus ranarum)
  • Family Ancylistaceae
    • Conidiobolus (Conidiobolus coronatus/Conidiobolus incongruus)

Oomycosis in animals

The term oomycosis is used to describe oomycete infections. These are more common in animals, notably dogs and horses. These are heterokonts, not true fungi. Types include pythiosis (caused by Pythium insidiosum) and lagenidiosis.

Zygomycosis has been described in a cat, where fungal infection of the tracheobronchus led to respiratory disease requiring euthanasia.

Zygomycosis in natural disasters

Zygomycosis has been found in survivors of the 2004 Indian Ocean earthquake and tsunami and in survivors of 2011 Joplin, Missouri tornado.

References