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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