Trichinella spiralis

Physiology and Structure
  • Trichinella spiralis is the etiologic agent of trichinosis.
  • The adult form usually lives in the duodenal and jejunal mucosa of flesh-eating mammals worldwide.
  •  The infectious larvae is found in the muscles of carnivorous and omnivorous animals.
  • Infection begins when meat containing the larvae is digested.
  • The development of it into an adult takes about 2 days.
  • A fertilized female can produce up to 1500 larvae in 1 to 3 months.
  • The encysted larvae remain viable for many years and are infectious if ingested by a new animal host.

 

 

 

 

Trichinella spiralis

 https://www.flickr.com/photos/pliabletrade/1582087824/

 

 

 

Lifecycle of Trichinella spiralis

 https://www.flickr.com/photos/15930189@N02/1953463675/

 

 

 Clinical Symptoms

  • Victims have minimal or no symptoms.

  • Victims with no more then 10 larvae per gram of tissue are asymptomatic whereas people infected with around 100 larvae have the significant disease. Victims who are infected with at least 1000 to 3000 larvae have a serious case.

  • Patients with mild infections may experience influenza-like syndrome with slight fever and mild diarrhea.
  • Those who suffer from extensive larval migration would experience persistent fever, gastrointestinal distress, muscle pain, etc.
  • In heavy infections, severe neurologic symptoms (e.g psychosis, meningoencephalitis and cerebrovascular accident) may occur.
  • For lethal trichinosis, the patient dies 4 to 6 weeks after infection due to respiratory arrest and muscle destruction.
 
Treatment, Prevention and Control
  • Treatment is primarily symptomatic as there are no good antiparasitic agents for tissue larvae.
  • Adult worms are usually treated with mebendazole, with would halt the production of new larvae.
  • Microwave cooking, drying or smoking the meat do not kill the larvae.
  • Feeding of garbage to pigs is not encouraged in order to control transmission.
  • Quick freezing of pork at -40 °C destroys the organisms.

 

 

 

 

 

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Parasite is defined as an organism that derives its nutrients from another living organism, the host. Parasitic diseases are usually referred to those caused by protozoa, helminths and arthropods which love at the expense of their host. Successful parasites are the ones who are able to maintain their own life processes without killing their host.

Several ways to distinguish parasites infection and bacteria/viruses infection:

  1. Parasites have a complex life cycle that involves the formation of resistant cyst in the organism. (it can usually survive for long periods outside the host.)
  2. Life cycle might involve an insect vector (carrier) that is important for the transmission of disease. In most cases, it is impossible to eliminate the vector effectively.
  3. Some parasites are capable of infecting both humans and animals, thus both can act as reservoirs for the infection. This is true for most protozal infections carried by insects.
  4. Many parasites has life cycle that requires enough time to allow for the various stages to mature, either in soil or in an insect or host.