Assoc. Prof. Anchalee Wannasan

Department of Parasitology,

Faculty of Medicine, CMU พ.วพ. 330219

Trichinella spiralis

Trichuris trichiura

Capillaria philippinensis

Intestinal roundworm infection II

1. Can identify and explain morphology and life cycle

of Trichinella spiralis, Trichuris trichiura and

Capillaria philippinensis

2. Can describe the diseases caused by the parasites

in terms of their transmission, pathology,

symptoms, diagnosis and prevention

Helminths

Nemathelminthes Platehelminthes• Phylum

Trematoda CestodaNematoda• Class

Secernentea• Sub-class Adenophorea

- A. lumbricoides

- Toxocara spp.

- Hookworms

- S. stercoralis

- A. cantonensis

- G. spinigerum

- D. medinensis

- Filarial worms

- E. vermicularis

• Trichinella spiralis

• Trichuris trichiura

• Capillaria spp.

Phasmids Aphasmids

1. Lack a pair of chemoreceptor sensory organs (phasmids)

2. Esophagus surrounded by stichosome: a row of gland cells (stichosome)

Unique morphologic features of Aphasmids

stichosome

stichocyte

mouth esophagus

Trichinella spiralis

• Disease : Trichinosis, Trichinellosis

• Distribution : Cosmopolitan distribution

Temperate > Tropics and subtropics

• Definitive host : carnivorous and omnivorous vertebrate animals

• Habitat : mucosa of small intestine

• Mode of infection :

ingestion of raw or undercooked meat containing

encysted first stage larvae

Morphology

• Smooth cuticle

• Slender anterior :-

o mouth (protusible stylet)

o esophagus surrounded by stichosome

o stichocytes (gland-like cells)

• Posterior :-

M : - curve tail with 2 copulatory

appendages at the end tail

- no spicule

- have cloaca

F : - ovary and anus

copulatory appendagescopulatorycopulatory appendagesappendages

Adult male

1-1.5 x 0.03-0.04 mm.

copulatory appendages

Anterior end

vulva

• ovoviviparous

• larviposition

Adult female2 times longer than male

• Newborn larva (NBL)

- approximately 100 x 6 µm in size

- compose of nuclei

- invade into lymphatic and blood vessels

• Encapsulated larva (muscle larva)

- First stage larva (L1)

- infective stage (1mm.)

- Nurse cell is parallel with other

striated muscle cells

- collagen capsule formation

Larvae

• NBL occupies a skeletal muscle cell

and changes cell activities.

• Nurse cell : The cell whose function

appears to be to support or nourish

another cell.

• encapsulated with collagens

• Larva stops development but can

survive for several years.

• die from calcification

veinule

arteriole

infective larva

nurse cell

Nurse cell-parasite complex

2 D.

~20 D.~5 D.

Life cycle

• Incubation period is about 5-15 days.

• Pathology and symptoms of trichinosis are consistent

with the developmental stages in the human

• Severity of the disease depends on

- human host age

- immunological status of host

- numbers of larvae ingested

Pathology and Symptoms

1. Intestinal phase

2. Muscle invasion phase

3. Convalescence phase

• malaise, nausea, vomiting,

abdominal cramps,

non-bloody diarrhea

Misdiagnosis : Food poisoning from bacterial infection

• Penetration of adult in mucosa

(inflammation of intestinal mucosa)

1. Intestinal phase (~2-7 D.)

• fever, eosinophilia, muscle pain

edema, pseudohypertrophy,

movement difficulty, breathing problem

extremely weakness (pseudoparalysis)

• CNS, cardiac and pulmonary involvement :

neurological disturbance, myocarditis, encephalitis, pneumonitis

death

• Throughout the circulatory and lymphatic systems,

newborn larvae invade skeletal muscles,

resulting in vasculitis and tissue damage

2. Muscle invasion phase (~1-5w.)

http://www.cmaj.ca/content/176/4/449.full

Skin Rashes

pseudohypertrophy

•

Periorbital edema

Dalcin et al., 2016

• Signs and symptoms are subside

and almost disappear

• Encapsulation of larvae

death

• Major complications are

encephalitis and myocarditis

(congestive heart failure).

• Secondary infection:

pneumonitis or sepsis, etc.

3. Convalescence phase (~5-6w.)

• Trichinosis is zoonosis.

• group infection

• Transmission in Thailand involved with

- free roaming pigs

- consuming wildlife meat

Epidemiology

1) History of eating undercooked meat (from endemic area?)

2) Clinical manifestations (at least 3 to 5 signs)

- edema (face & eyelid)

- muscular pain

- fever > 38oC

- eosinophilia (30-80%)

- increasing of musclular enzyme level

creatine kinase (CK)

lactate dehydrogenase (LDH)

aspartate aminotransferase (AST)

Diagnosis

3. Xenodiagnosis (mild case)

4. Serodiagnosis

• ELISA

- Ab serum (positive after 3w post-infection)

- determine the prevalence and early infection

• IFA and Western blotting : detect Ab serum

5. PCR : distinguish and identify species

6. Definitive diagnosis

• Histological examination

• Compression method

• Artificial digestion method

Muscle biopsy

• Histological method

• Compression method

https://www.mcdinternational.org/trainings/malaria/english/DPDx5/HTML/ImageLibrary/S-Z/Trichinellosis/body_Trichinellosis_il3

Digestion method

• Adult in intestine

- Mebendazole

- Albendazole

• No drug is effective to the muscle larvae

• supportive and symptomatic treatment

(analgesics and corticosteroid)

may be required in severe cases

Treatment

• Sausage were cause of many infected cases.

• Generally, deep freezing meat at -15oC for 20 days can

effectively kill muscle larvae.

• Clean meat grinders after each use.

Prevention

no effects to kill the muscle larvae by…

smoking

drying

microwaving

curing (salting)

• Distribution: worldwide,

especially in poor sanitation areas of tropical

zones with heavy rain

• Disease : Trichuriasis

Trichuris trichiura

• Definitive host : human

• Habitat : mucosa of large intestine

• Mode of infection : fecal-oral transmission

by ingestion of infective eggs from contaminated soils, hands,

food, or water

• Adult

- whip-like worm

- stylet mouth

- esophagus with stichosome

- thin anterior part (2/3)

- thick posterior part (1/3)

Morphology

Male

- 35-45 mm. in length

- curled caudal tail

- A spicule protrudes through a spiny sheath

(helpful in copulation)

Adult Male

Female - 35-50 mm.in length

- linear caudal tail

- vulva opening at the end of esophagus

Adult Female

• size : 50-54 x 22-30 µm.

• barrel shape

• smooth, bile stained (brown), thick eggshell

• hyaline bipolar mucoid plugs

• unembryonated when passed in stool

Egg

embryonated egg

3 weeks

In man ~3 M.

Life cycle

• soil transmission (same as Ascaris worm)

• frequently reports from areas with :

- tropical weather

- poor sanitation practices

- among crowded population

(prison, kindergarten, etc.)

• Endemic areas of Thailand are in the

southern part.

• In 2002, estimated number of infected

persons was about 1 billion worldwide.

Epidemiology

โดย..กรมควบคุมโรคกระทรวงสาธารณสุขโครงการควบคุมโรคหนอนพยาธิตามพระราชด าริฯ ในปี พ.ศ.

อตัราการติดเช้ือหนอนพยาธิในอุจจาระในนกัเรียน 7.62 % (6,107 / 80,127 คน)

• Light infection : asymptomatic

• Heavy infection (traumatic damage by worm’s penetration)

- chronic, mucus and bloody diarrhea

- abdominal cramps, nausea, anorexia

- malnutrition, severe anemia, allergy (toxic damage)

- growth retardation in infant case

- rectal tenesmus

- rectal prolapse

Pathology and Symptoms

• Rectum becomes unattached

inside the body and comes out

through the anus

Prolapsed rectum

• Clinical diagnosis

- symptoms of trichuriasis are similar

to those of hookworm infection

- long standing blood loss with anemia

Diagnosis

Anterior part

endoscopic finding

• Specific diagnosis

- proctoscopy to find out adult worms

- microscopic identification eggs in feces

- In light infections, concentration method

such as Kato-Katz or formalin-ether methods

are recommended

Cecum cross section

Endoscopic finding

• Ingest adequate processed food

Wash, peel, or cook all fresh vegetables and fruits before

eating, particularly those that are grown in soil fertilized with

human feces (fertilizer).

• Not defecating outdoors.

• Effective sewage disposal systems.

• Hygiene education:

custom of hand washing before handling food

• Drugs of choice :

Mebendazole, Albendazole

Prevention and treatment

Capillaria philippinensis

• Disease : Intestinal capillariasis (Philippine capillariasis)

• Distribution : endemic in Philippines,Thailand

sporadic cases from East and Southeast Asian countries and northern Egypt

• Definitive host : Human

• Habitat : small intestine

• Mode of infection :

ingesting infected freshwater fish or

brackish-water fish

Adult

• Anterior part

has esophagus surrounded by

stichosome.

• Posterior part

composes of intestinal and genital

organs.vulva

spicular sheath

stichosome

spicule

Morphology

MF

anterior end

spicule

spicular sheath

• Posterior end presents a spicule

with long smooth spicular sheath

Adult Male 2.3-3.2 mm. in length

anterior end

vulva

• vulva opening at the end of esophagus

Adult Female 2.5-4.3 mm. in length

• similar as the egg of Trichuris trichiura

• peanut shaped

• flattened bipolar mucoid plugs

• thick egg shell with transverse pattern

https://www.sciencesource.com/CS.aspx?VP3=LoginRegistration&L=True&R=FalseC. airophila

Trichuris eggCapillaria egg

Egg Size : 30-40 x 20 µm

• DH : human with autoinfection

• HT : small intestine

(both oviposition and larviposition)

• IH : freshwater fish or

brackish-water fish

LIFE CYCLE

นกยางกรอกพนัธุ์จีน

wildlife reservoir host

(migratory fish-eating birds)

นกกวกั

Intermediate host

(small freshwater fish or brackish-water fish)

ปลาซิว, ปลาไน, ปลาตะเพียนขาว, ปลากริมขา้งลาย,

ปลาหวัตะกัว่, ปลาหางนกยงู

• The worms directly penetrate epithelium and submucosa

of small intestine and also secrete proteolytic enzymes.

• Resulting in cellular injury and dysfunction :-

inflammation, atrophied crypts, flattened villi

and degeneration of epithelium and submucosa

Pathology and symptoms

• Main symptoms :

malabsorption, protein-losing enteropathy,

electrolyte disturbance, abdominal pain,

bloating, burborygmi, chronic watery

diarrhea

fatique, weight loss, muscle weakness,

anorexia, dizziness and edema, etc.

• Complications :

cardiomyopathy, cerebral edema,

severe emaciation, cachexia and death

cachexia

• clinical manifestation

• definitive diagnosis :

presence of adults, larvae

or eggs by examination of

stool or intestinal biopsy

(autoinfection)

• serological examination

Diagnosis

https://www.omicsonline.org/india/capillariasis-peer-reviewed-pdf-ppt-articles/

intestinal biopsy specimen, stained with H&E

• Supportive treatment

• Drugs of choices are mebendazole and albendazole.

• Avoid to eat uncooked fresh water fish (intermediate host).

Treatment and Prevention

Recommended books and websites

• Leelayoova S., et al. Lecture notes on medical

parasitology.1st edition, Bangkok: Phramongkutklao College

of Medicine Book Project, 2015.

• Roberts LS, Janovy JJ, Nadler S. Gerald D. Schmidt, Larry

S. Roberts' Foundations of Parasitology. 9th ed. New York:

McGraw-Hill; 2013.

• https://w1.med.cmu.ac.th/parasite/nematode/

• https://www.cdc.gov/parasites/az/index.html