Sphaerothecum destruens - Molecular diagnosis (PCR); Molecular identification (sequencing).
Information 24-07-2014. 

Sphaerothecum destruens is a protist intracellular parasite, which is currently in a single phylogenetic branch between fungi (Fungi Kingdom) and animals (Kingdom Animalia). It has an intracellular phase and a mobile phase extracellular flagellum (zoospore). Extracellular mobile zoospora is activated in contact with fresh water, which facilitates its spread to new hosts. His current interest lies in its ability to infect many hosts. Some without suffering any consequences, but yet others provokes morbidity and / or mortality. It is not specific host, so it can infect many species. Derives its interest that may affect salmon and trout are very susceptible to infection, as has been shown experimentally to
be transmitted to them. Sphaerothecum destruens is an example of pathogen introduced invasive species that pose a risk to native species.

Initially introduced in Europe from China and the former USSR, along with herbivorous fishes (Hypophthalmichthys molithrix, H. nobilis, grass carp), taken for fish breeding farms in Eastern European countries such as Romania and Hungary. Since they have been invaded in the past 40 years, about 5 new countries every decade.

The primary route of infection outside their place of origin, through procedures aquaculture, sport fishing, or the introduction of ornamental fish, among other possible tramways. The secondary path would consist of their own ability to natural dispersion.

are many potential hosts such as coho salmon, O. mykiss, Salmo trutta, Salvelinus fontinalis. An example of host acts only as a carrier to be free from disease, it is the invasive fish cyprinidae Pseudorasbora parva (false rasbora) of about 6 to 11 cm, which is an invasive species, and contain some parasites as Sphaerothecum destruens or Anguillicola crassus, is considered potential for native aquatic fauna danger.

Other cyprinids, leucaspius delineatus, fathead minnows, Abramos Brama, have the disease. In this sense, leucaspius delineatus has experienced a decline since the invasion of stone moroko.
It also affects salmon as Oncorhynchus tshawytscha (American salmon) and European salmon (Salmo salar).

A infected fish, suffering
from disease after infection, they can cause two types of illness: 1) disseminated form, with enlargement of liver, kidney or spleen, where spores and stages of development are widely distributed in the host, with little organic cellular response; and 2) limited or nodular form, with presence of nodules in the liver, kidney, spleen, heart, mesentery, with a chronic inflammatory response, which is accompanied by granuloma formation in various internal organs.

To detect their presence, it can proceed to visualize histological sections stained, or stained smears prepared from samples of kidneys, liver, gonads and gills; or to detect DNA by molecular methods of PCR (polymerase chain reaction). The latter procedure is keen to diagnose subclinical infections.

Tests in IVAMI:

  • Molecular detection duplex PCR (nested PCR) of Sphaerothecum destruens by dissection, obtaining liver and kidney, or other organs if requested, to confirm the amplicon obtained by sequencing.

Preservation and shipment of sample:

  • Refrigerated (preferred) for less than 2 days.
  • Frozen: over 2 days.

Cost of testing: consult ivami@ivami.com.