Trichinela spiralis Doug Mandler & Albert Teo PRESENTS.

Trichinela Trichinela spiralisspiralis

Doug Mandler & Albert TeoDoug Mandler & Albert Teo

PRESENTSPRESENTS

TaxonomyTaxonomy

Kingdom:Kingdom: AnamaliaAnamaliaPhylum:Phylum: NematodaNematoda

Class:Class: Adenophorea Adenophorea Order: Order: TrichocephalidaTrichocephalida

Family: Family: TrichinellidaeTrichinellidaeGenus: Genus: TrichinellaTrichinella

Species: Species: spiralisspiralis

* Please note that we will be discussing 5 * Please note that we will be discussing 5 different different subspeciessubspecies of of Trichenella spiralisTrichenella spiralis

General Facts General Facts

Able to infect a wide range of mammalian Able to infect a wide range of mammalian hosts hosts

Trichinellosis is the collective term used to Trichinellosis is the collective term used to describe the diseases that this parasite describe the diseases that this parasite cause cause

Considered endemic in Japan and ChinaConsidered endemic in Japan and China Top carnivores are usually infectedTop carnivores are usually infected Smallest nematode of humansSmallest nematode of humans Trichinella spiralis Trichinella spiralis is the worlds largest is the worlds largest

intracellular parasite. intracellular parasite.

Question!Question! There are five different subspecies for There are five different subspecies for

Trichinela spirals. Trichinela spirals. Can you name one of Can you name one of them? them?

5 subspecies are: 5 subspecies are: - T. spiralis T. spiralis (T1)(T1)- T. nativa T. nativa (T2)(T2)- T. britoviT. britovi (T3) (T3)- T. pseudospiralis T. pseudospiralis (T4)(T4)- T. nelsoniT. nelsoni (T7) (T7)

Geographic RangeGeographic Range

WorldwideWorldwide Most common in parts of Europe and Most common in parts of Europe and

the United States. the United States.

Definitive HostDefinitive Host

Almost any species of mammal can get Almost any species of mammal can get affected affected - Humans Humans - Pigs/boarsPigs/boars- BearsBears- Walruses Walruses - Tasmanian devil Tasmanian devil - Raccoon dogs Raccoon dogs

Domestic pigs are the main reservoir host for Domestic pigs are the main reservoir host for T. spiralisT. spiralis

MorphologyMorphology

Morphology cont. Morphology cont.

The males measure 1.5 mm in length The males measure 1.5 mm in length by 36 µm in diameterby 36 µm in diameter

Females are about twice the size of Females are about twice the size of males (measuring 3 mm in length by males (measuring 3 mm in length by 36 µm in diameter) 36 µm in diameter)

Larvae are about 0.08 mm long by 7 Larvae are about 0.08 mm long by 7 µm in diameter µm in diameter

Life Cycle CDCLife Cycle CDC

Life Cycle in pictureLife Cycle in picture

Question IIQuestion II

• How many newborn larvae are How many newborn larvae are estimated to be shed from the adult estimated to be shed from the adult female in her life time?female in her life time?

~ 500 to 1,500~ 500 to 1,500

Life Cycle in wordsLife Cycle in words

Adult worms live around the columnar epithelial Adult worms live around the columnar epithelial cells of the small intestine and the larvae live in cells of the small intestine and the larvae live in striated muscle cells of the same mammalstriated muscle cells of the same mammal

The worm can infect any species of mammal The worm can infect any species of mammal that consumes its encysted larval stages (Nurse that consumes its encysted larval stages (Nurse cell complex)cell complex)

While in the small intestine, they are considered While in the small intestine, they are considered to be intracellular-multicellular organisms to be intracellular-multicellular organisms

In order for the life cycle to continue, an In order for the life cycle to continue, an infected host must die and be eaten by another infected host must die and be eaten by another mammal mammal

Life Cycle : Enteral PhaseLife Cycle : Enteral Phase

When an animal eats meat that contains infective When an animal eats meat that contains infective TrichinellaTrichinella cysts, the acid in the stomach dissolves cysts, the acid in the stomach dissolves the hard covering of the cyst and releases the the hard covering of the cyst and releases the worms worms

The worms pass into the columnar epithelium of the The worms pass into the columnar epithelium of the small intestine and, in 1–2 days (30 hours), become small intestine and, in 1–2 days (30 hours), become mature (molts about 4 times) mature (molts about 4 times)

After mating, adult females produce larvaeAfter mating, adult females produce larvae The female is The female is ovo-viviparousovo-viviparous. This means that she . This means that she

produces eggs, but doesn't lay them until they have produces eggs, but doesn't lay them until they have already hatched in her uterus already hatched in her uterus

She lays her living larvae within the small intestine She lays her living larvae within the small intestine beginning the fifth or sixth day after infectionbeginning the fifth or sixth day after infection

Life Cycle : Parenteral Life Cycle : Parenteral PhasePhase

Parenteral phase begins approximately one week Parenteral phase begins approximately one week after infection and may last several weeks after infection and may last several weeks

Larvae breaks through the intestinal wall and travel Larvae breaks through the intestinal wall and travel through the lymphatic system to the circulatory through the lymphatic system to the circulatory system to find a suitable cell system to find a suitable cell

Larvae can penetrate any cell, but can only survive in Larvae can penetrate any cell, but can only survive in skeletal muscle (sword-like stylet)skeletal muscle (sword-like stylet)

Within a muscle cell, the worms curl up and direct Within a muscle cell, the worms curl up and direct the cell functioning much as a virus does. The cell is the cell functioning much as a virus does. The cell is now called a nurse cell complex. Soon, a net of blood now called a nurse cell complex. Soon, a net of blood vessels surround the nurse cell, providing added vessels surround the nurse cell, providing added nutrition for the larva insidenutrition for the larva inside

The Nurse cell-parasite complex can live for as long The Nurse cell-parasite complex can live for as long as the host remains alive as the host remains alive

Question IIIQuestion III

• What is the only way of getting What is the only way of getting infected?infected?

~ Ingesting raw or undercooked ~ Ingesting raw or undercooked meat that contains the parasitemeat that contains the parasite

Clinical SignsClinical Signs

Dysentery due to invasion by adult worms Dysentery due to invasion by adult worms Migrating juveniles cause pain as they Migrating juveniles cause pain as they

invade muscle tissue; there may also be invade muscle tissue; there may also be edema (swelling), delirium, cardiac and edema (swelling), delirium, cardiac and pulmonary difficulty, pneumonia, nervous pulmonary difficulty, pneumonia, nervous disorders, deafness and delayed or lost disorders, deafness and delayed or lost reflexesreflexes

Fever can also be causedFever can also be caused Many cases are never diagnosed because of Many cases are never diagnosed because of

the vagueness of the symptomsthe vagueness of the symptoms

Clinical Signs ContinuedClinical Signs Continued

Severe symptoms include:Severe symptoms include: High feverHigh fever severe muscle painsevere muscle pain skin rash skin rash headachesheadaches swelling of eyelids, face, or extremitiesswelling of eyelids, face, or extremities

More Clinical SignsMore Clinical Signs Patients may develop neurologic manifestations that

rarely appear before the end of the second week of infection and provoke distress.

Headache, vertigo and tinnitus, deafness, aphasia, convulsions, and abnormalities related to peripheral reflexes, among others, are frequent complaints or signs found in severely infected individuals.

Generally, patients are alert but apathetic, and prolonged insomnia affects their behavior, causing them to become irritable.

Other neurologic symptoms such as meningitis, encephalitis, and/or hemiplegia may develop in relation to diffuse damage of brain tissue due to occlusion of arteries or to granulomatous inflammation

Edema of the face,Edema of the face,eyelids, hands, and eyelids, hands, and feet are a prominent feet are a prominent feature of mild feature of mild symptoms.symptoms.

ComplicationsComplications

Stillbirths in pregnant womenStillbirths in pregnant women Hearing loss Hearing loss Weight disordersWeight disorders Loss of hair and nailsLoss of hair and nails Disturbance of menstruationDisturbance of menstruation Muscle stiffnessMuscle stiffness Death may occur from heart failure Death may occur from heart failure

or central nervous system failureor central nervous system failure

DiagnosisDiagnosis A blood test or muscle biopsy can identify A blood test or muscle biopsy can identify

trichinosis. Stool studies can identify trichinosis. Stool studies can identify adult worms, with females being about 3 adult worms, with females being about 3 mm long and males about half that size mm long and males about half that size

Xenodiagnosis can also be done, where a Xenodiagnosis can also be done, where a lab rat is fed with a suspected piece of lab rat is fed with a suspected piece of tissuetissue

DNA tests amplified with PCR have found DNA tests amplified with PCR have found T. spirals.T. spirals.

ELISA testELISA test

TreatmentTreatment

Symptoms can be treated with aspirin Symptoms can be treated with aspirin and corticosteroids and corticosteroids

Thiabendazole can kill adult worms in the Thiabendazole can kill adult worms in the intestine; however, there is no treatment intestine; however, there is no treatment that kills the larvae. that kills the larvae.

Immunity for this parasite appears to be Immunity for this parasite appears to be lifelong. lifelong.

Neurological symptoms need to be Neurological symptoms need to be treated with steroids due to treated with steroids due to inflammation.inflammation.

Control & PreventionControl & Prevention Cook pork thoroughly (also flesh of bear, walrus, wild Cook pork thoroughly (also flesh of bear, walrus, wild

pigs) pigs) Cook all garbage fed to hogs Cook all garbage fed to hogs Proper meat handling, ordinary curing and salting of Proper meat handling, ordinary curing and salting of

pork products will not kill encysted juveniles pork products will not kill encysted juveniles Freezing is effective if carried out properly. The freezing Freezing is effective if carried out properly. The freezing

requirements differ with the size of the meat. Pieces not requirements differ with the size of the meat. Pieces not exceeding 6 inches in thickness require 20 days at 5ºF, exceeding 6 inches in thickness require 20 days at 5ºF, 10 days at -10ºF, 6 days at -20ºF. Larger pieces require 10 days at -10ºF, 6 days at -20ºF. Larger pieces require longer periods. Quick freezing and storage for 2 days is longer periods. Quick freezing and storage for 2 days is effective. effective.

Cook wild game meat thoroughly. Freezing wild game Cook wild game meat thoroughly. Freezing wild game meats, unlike freezing pork products, even for long meats, unlike freezing pork products, even for long periods of time, may not effectively kill all the worms. periods of time, may not effectively kill all the worms. This is because the species of trichinella that typically This is because the species of trichinella that typically infects wild game is more resistant to freezing than the infects wild game is more resistant to freezing than the species that infects pigs. species that infects pigs.

The Centers for Disease Control and Prevention The Centers for Disease Control and Prevention makes the following recommendation: "Curing makes the following recommendation: "Curing (salting), drying, smoking, or microwaving meat (salting), drying, smoking, or microwaving meat does not consistently kill infective worms." does not consistently kill infective worms." However, under controlled commercial food However, under controlled commercial food processing conditions some of these methods processing conditions some of these methods are considered effective by the United States are considered effective by the United States Department of Agriculture.Department of Agriculture.

An ELISA for swine trichinellosis is now An ELISA for swine trichinellosis is now approved for the certification of pork by the approved for the certification of pork by the U.S. Department of Agriculture.U.S. Department of Agriculture.

Question IVQuestion IV

• Where do outbreaks occur most Where do outbreaks occur most frequently?frequently?

~ In a community or among family ~ In a community or among family membersmembers

ReferencesReferences http://animaldiversity.ummz.umich.edu/site/http://animaldiversity.ummz.umich.edu/site/

accounts/information/Trichinella_spiralis.htmlaccounts/information/Trichinella_spiralis.html http://www.trichinella.org/http://www.trichinella.org/ http://ucdnema.ucdavis.edu/imagemap/nemmap/http://ucdnema.ucdavis.edu/imagemap/nemmap/

ent156html/nemas/trichinellaspiralisent156html/nemas/trichinellaspiralis http://www.phac-aspc.gc.ca/msds-ftss/http://www.phac-aspc.gc.ca/msds-ftss/

msds155e.htmlmsds155e.html http://www.dpd.cdc.gov/dpdx/html/http://www.dpd.cdc.gov/dpdx/html/

Trichinellosis.asp?body=Frames/S-Z/Trichinellosis.asp?body=Frames/S-Z/Trichinellosis/body_Trichinellosis_page1.htmTrichinellosis/body_Trichinellosis_page1.htm

http://www.cdc.gov/ncidod/dpd/parasites/http://www.cdc.gov/ncidod/dpd/parasites/trichinosis/factsht_trichinosis.htmtrichinosis/factsht_trichinosis.htm

http://cmr.asm.org/cgi/reprint/9/1/47http://cmr.asm.org/cgi/reprint/9/1/47