Species/Subspecies: Aphanomyces astaci
Category: Animal pathogen
Etymology: Genus name: invisible fungus.
Species epithet: from crayfish.
Common name: Kräftpest
Significance:Is of great importance in Sweden because this organism has eradicated large parts of the Swedish crayfish population, due to the spread caused by implantation of the signal crayfish (which is resistant).
Geographic distribution: The natural range of A. astaci is probably North America where the wild crayfish, signal crayfish, is resistant to the disease. The signal crayfish can carry the organism and spread it further, as it has done to large parts of Europe, posing a serious threat to the European crayfish.
 Note that members of phylum Oomycota do not belong to the actual fungi (Kingdom: Fungi), but belong to a separate group (Kingdom: Chromista), which are also called water moulds (or water molds).
Macromorphology (smell):
Spec. Char.:
Hosts/materialDisease/effectClinical picture or result
European crayfish (Astacus astacus)Crayfish plagueThe first signs of illness are high mortality. Then you can also see on the crayfish that the tail muscles fade or become brownish due to the encapsulated hyphae of the water mould by crayfish blood. The crayfish is a nocturnal animal and if it shows up during the day, it can be a sign of illness.
Genome Sequence:
ACC-No GenBankStrain/Isolate# of chromSize (Mbp)
GCA_000520075 APO3  58.6 

Mitochondrial DNA sequence:
ACC-No GenBankStrain/IsolateNumber of BP
NC_032051 AP03 49 489 
Circular DNA

18S rRNA Seq:
ACC-No GenBankStrain/IsolateNumber of NT
XR_717101 APO3 1807 

Taxonomy/phylogeny: Note that this group of organisms does not belong to the kingdom Fungi but instead to the kingdom Chromista, and it is believed that they are closely related to brown algae and diatoms.
Legislation: Crayfish plague is notifiable to the World Organization of Animal Health (OIE). In Sweden, the crayfish plague is also notifiable to the Swedish board of Agriculture.
Reference(s): No. 53, 54

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