Lecture 1: Nematodes 1 #AsturiaNOTES Parasitology: Trichuris trichiura, Trichinella spiralis, Capillaria philippinensis, and Enterobius Vermicularis

First, what is:  Nematoda?  A nematode?

Nematoda  A phylum (A phylum is a biological hierarchy as part of the biological classification of organisms)  Therefore, the members of the Phylum Nematode are then called nematodes

Nematodes  Common name: Roundworms  Elongated, cylindrical, non-segmented worms which are tapered at both ends  Possess: o Stiff Cuticle—which may be smooth or may be extended to form a variety of structures particularly at the: . Anterior end . Posterior end o Well-developed Digestive System . With both: 1 Oral opening a A buccal capsule furnished with cutting plates or teeth. 2 Anal opening . The esophagus is muscular in most forms of nematodes. 1 If the esophagus is expanded posteriorly into a bulb that contains a valve mechanism—the esophagus is rhabtidiform 2 If the esophagus is muscular and of uniform caliber throughout—the esophagus is filariform  Nematodes have separate sexes. Therefore, there is a female nematode and a male nematode. o The female is BIGGER than the male o The reproductive organs are tubular and lie coiled in the body cavity o In the Male: . There is a single tubule which at its smaller end consists of testicular cells 1 It extends into a vas deferens and seminal vesicle and terminates in an ejaculatory duct opening into the cloaca o In the Female: . Has two (2) cylindrical ovaries which expand into uteri 1 The uteri may open to the exterior through a single vulva, or there may be a common vagina between the vulva and uteri a The vulva is frequently located near the middle of the body but varies in position in different species  Most nematodes are planktonic or free-living o But some parasitize: . Humans . Animals . Plants

AsturiaNOTES by RAsturiano UST-FMS A-2019: #TheElusiveDoktora Page 1 of 11 August 12, 2015. Lecturer: Dr. O. Ng—downloadable (for free!) at: www.theelusivedokora.wordpress.com Lecture 1: Nematodes 1 #AsturiaNOTES Parasitology: Trichuris trichiura, Trichinella spiralis, Capillaria philippinensis, and Enterobius Vermicularis

 Requires an intermediate hosts are necessary for the larval development of some forms of nematodes.  Parasite forms of nematodes include: o Intestinal nematodes o Tissue-inhabiting nematodes

The parasitic nematodes:  Color: Light cream-white o Females of small nematodes are usually darker than males their eggs are dark- colored  Infective-stage larvae: Have a filariform type of esophagus  Free-living stages of nematodes: Have a rhabtidiform esophagus

A. Trichuris trichiura  Common name: Whipworm  Thick posterior part, thin anterior portion—resembling the shape of a whip thus earing its common name  2nd most common intestinal worm next to Ascaris  Occurs in moist, warm, tropical regions of Asia, Central and South America, and the Caribbean Islands

Morphology  Color: Flesh or pinkish  Size: Females are Longer and Bigger o Females: 3.5 cm to 5.5cm o Males: 3 cm to 3.5 cm  Anterior 3/5 o With fine hair-like structures which form the esophagus . The Esophagus is characteristically embedded in glandular cells called Stichocytes  Posterior 2/5 o Contains: . The intestine . The reproductive organs o Tail end: . Females: Straight and blunt . Male: Curved at 360deg

Egg  Barrel shaped  Thick, smooth brown egg shell and 2 transparent polar plugs protruding from both poles  The female worm produces 3,000-7,000 eggs daily (eggs are 50 to 54 microns in length)  The zinc sulfate flotation method is extremely efficient in demonstrating these eggs

AsturiaNOTES by RAsturiano UST-FMS A-2019: #TheElusiveDoktora Page 2 of 11 August 12, 2015. Lecturer: Dr. O. Ng—downloadable (for free!) at: www.theelusivedokora.wordpress.com Lecture 1: Nematodes 1 #AsturiaNOTES Parasitology: Trichuris trichiura, Trichinella spiralis, Capillaria philippinensis, and Enterobius Vermicularis

Life Cycle  1—Eggs are passed out in the feces o The eggs passed out in the feces are fertilized eggs—the diagnostic stage  2—In the soil, the eggs embryonate under favorable conditions o The embryonated egg is the infective stage  3—The embryonated egg (infective egg) is ingested by the human host and it hatches in the intestines o It takes 2-3 months after ingestion before the fertilized eggs can be seen in the feces of the host  4—The liberated larva from the embryonated egg burrows into an intestinal villus for a few days  5—Then it takes up its residence in the lumen of the cecum and develops into maturity where the female can have her eggs fertilized and pass these eggs out in the feces and repeat #1 o In heavy infections, the worms can be found in the rectum

Pathogenesis  The anterior ends of the worms, interlaced in the colonic mucosa, produce little damage to the host unless present in large numbers.  Appendicitis is frequently present.  Concomitant infection with bacteria is frequently present.  Edema of the rectum, produced by numbers of worms in that area, is responsible for rectal prolapse  If infection is = or > 200 worms in children, chronic dysentery can occur along with: o Profound anemia o Growth retardation  Resembles presentation of inflammatory bowel disease  NO heart-lung migration  Does NOT lodge in the liver  Mimics Inflammatory Bowel Disease

Symptoms  Light infections by Trichuris trichiura are usually asymptomatic  Heavier infections are associated with the following: o Abdominal pain and distention o Bloody or mucoid diarrhea o Tenesmus . Tenesmus—A distressing but ineffectual urge to evacuate the rectum or urinary bladder o Hypoalbuminemia o Weight loss and Weakness o Rectal prolapse . The rectum is edematous and worms may be visible on it o Anemia and moderate eosinophilia o Nutritional deficiencies  Therefore, the intensity of the symptoms is directly correlated with the bioburden. o Therefore, more worms? The more intense the symptoms!

AsturiaNOTES by RAsturiano UST-FMS A-2019: #TheElusiveDoktora Page 3 of 11 August 12, 2015. Lecturer: Dr. O. Ng—downloadable (for free!) at: www.theelusivedokora.wordpress.com Lecture 1: Nematodes 1 #AsturiaNOTES Parasitology: Trichuris trichiura, Trichinella spiralis, Capillaria philippinensis, and Enterobius Vermicularis

. If untreated, the worms can survive for 4-8 years.

Diagnosis  Direct Fecal Smear (DFS)  Cellophane thick smear method or the Kato Thick Smear

Epidemiology  In the Philippines: o Prevalence of Trichuris infection is 80-90%, almost parallel with Ascaris infection o Most infections are light o Trichuris eggs are more susceptible to adversities than Ascaris eggs

Treatment  Albendazole o 400mgs in a single dose for 3 days  Mebendazole  Oxantel-Pyrantel

B. Trichinella spiralis  Can cause: o Trichinosis o Trichiniasis o Trichinelliasis  There are 8 species belonging to the genus Trichinella and 5 of them parasitize humans and carnivorous animals. o The other 4: . Trichinella nelsoni—2nd to the Trichinella spiralis in parasitizing humans . Trichinella native . Trichinella britovi . Trichinella pseudospiralis o Three additional species have been described: . Trichinella murrelli . Trichinella zimbabwensis . Trichinella papuae  Trichinella spiralis o Infection is initiated by consumption of raw/undercooked pork/meat containing the encysted larvae . Upon ingestion, the encysted larvae will excyst after action of gastric acid. The end result of this is the liberation of the larvae which will penetrate into the intestinal mucosa. 1 Upon attachment, the larvae quickly develop into the adult forms in 30 to 40 hours

Morphology  T. spiralis is a small worm  Sexes are separate:

AsturiaNOTES by RAsturiano UST-FMS A-2019: #TheElusiveDoktora Page 4 of 11 August 12, 2015. Lecturer: Dr. O. Ng—downloadable (for free!) at: www.theelusivedokora.wordpress.com Lecture 1: Nematodes 1 #AsturiaNOTES Parasitology: Trichuris trichiura, Trichinella spiralis, Capillaria philippinensis, and Enterobius Vermicularis

o Female is BIGGER than male o Female—3.50mm longs o Male—1.50mm long  Shape: Thread-like  Characteristics: o Anterior end . With small orbicular, non-papillated mouth 1 In females, the anterior 1/5 is with a single ovary with a vulva and long narrow digestive system o Posterior end . Females: Bluntly rounded . Males: Ventrally curved with 2 lobular appendages

Larvae  Has a spear-like burrowing tip at its tapering anterior end  Matured encysted larvae has digestive tract although the reproductive system is NOT fully developed

Life Cycle  1—Starting points are infected hogs and rats  2—If pork is eaten raw or undercooked, larvae will penetrate the intestinal wall that will mature in 2-3 days  3—Adults of Trichinella spiralis is now located in the wall of the small intestine, they mate, and produce larvae  4—Larvae will be carried in the blood and stream to skeletal muscle o When larvae become localized in the muscle, it becomes encapsulated o The larvae access the bloodstream when they are deposited into the intestinal mucosa and spread enter the lymphatic vesselsblood . The larvae, since they are in the blood, can be lodged into various tissues: 1 Myocardium 2 Brain 3 CSF 4 Body cavities o When the larvae located in the skeletal muscle mature into adult worms, the skeletal muscle exhibit degenerative and inflammatory changes . Stages of Muscle Invason by Trichinella spiralis: 1 Fever 2 Facial Edema 3 Myalgia and Malaise 4 Peripheral Eosinophilia . Damage to muscle may cause difficulty in: 1 Eye movement 2 Breathing 3 Chewing 4 Swallowing 5 Speech 6 Movement of Extremities (UE/LE)

AsturiaNOTES by RAsturiano UST-FMS A-2019: #TheElusiveDoktora Page 5 of 11 August 12, 2015. Lecturer: Dr. O. Ng—downloadable (for free!) at: www.theelusivedokora.wordpress.com Lecture 1: Nematodes 1 #AsturiaNOTES Parasitology: Trichuris trichiura, Trichinella spiralis, Capillaria philippinensis, and Enterobius Vermicularis

Diagnosis  The diagnosis can be made on the basis of clinical symptoms and history but should be confirmed by laboratory examination or serologic tests. o Several serologic tests are now available for Trichinella spiralis  Muscle biopsy o Muscle of choice is usually gastrocnemius o This can reveal the encysting larvae at any time after the first week of infection  Xenodiagnosis  Bachman Intradermal Test  History of o Eating or raw or inadequately cooked meat o Intestinal flu or rheumatic pain o Marked eosinophilia in blood o Swollen eyelids or severe conjunctivitis

Pathogenesis  The intestinal phase of Trichinella infection ends when the adult worms are rejected because of the development of local intestinal immunity. o Prolonged intestinal phase via the administration of corticosteroids  The primary pathogenic effect of Trichinella comes from destruction of the striated muscle fibers in which it encysts. o During the migration, from blood  muscle, vasculitis can occur accounting for the splinter hemorrhages and the periorbital edema . Vasculitis—inflammation of the blood or lymphatic vessel 1 Certain neurologic manifestations of trichinellosis may also be due to the vasculitis a Granulomas that sometimes contain Trichinella larvae have also been found in the brains of the patients who succumbed to this infection  Stage of Convalescence—End of the 3rd week of infection when larvae have encapsulated within skeletal muscle  Death from Trichinellosis is due to: o Myocarditis o Encephalitis with concomitant Meningitis o Pneumonitis

Treatment  No specific treatment is established  However, Thiabendazole can be administered o Effect: Greatly mitigate the illness when administered between the 5th and 9th day of infection

Prevention  Smoking, drying, and salting of meat are NOT effective preventive measures  Effective means: o Refrigeration/Freezing o Avoid feeding raw garbage to hogs

AsturiaNOTES by RAsturiano UST-FMS A-2019: #TheElusiveDoktora Page 6 of 11 August 12, 2015. Lecturer: Dr. O. Ng—downloadable (for free!) at: www.theelusivedokora.wordpress.com Lecture 1: Nematodes 1 #AsturiaNOTES Parasitology: Trichuris trichiura, Trichinella spiralis, Capillaria philippinensis, and Enterobius Vermicularis

o Extermination of rats around the farms o Thorough cooking of pork

C. Capillaria philippinensis  Causative agent for: Intestinal capillariasis o Characterized by: . Borborygmi—intestinal rumbling caused by moving gas . Intestinal malabsorption . Chronic Diarrhea

 First observed in 1962 in the province of Ilocos Sur (sabi ng book). Pero sabi sa lecture, Bacarra, Ilocos Norte (ano ba talaga, auntie? Imberna sa pes!) o It reached epidemic proportions with 1400 cases and 95 deaths  Occurs in other parts of the Philippines, Thailand, Taiwan, Japan, Korea, Egypt, Iran, and Colombia

Morphology  Adult worms are small and slender and they live in the jejunal mucosa where they may present in enormous numbers  Sexes are separate: o Female is BIGGER o Male: . Characterized by the presence of a chitinized spicule and a long spicule sheath extending beyond the length of the worm o Female: . Two types: 1 Typical (Oviparous)—8-10 eggs in utero arranged in a single row 2 Atypical (Larviparous)—40-45 eggs in utero arranged in 2-3 rows

Eggs  Color: Pale yellow  Structure: With a moderately thick striated shell with flattened bipolar plugs  Shape: Peanut  Size: 42 by 20 microns  Survivability: The egg voided by infected persons can develop outside the host and can be ingested by fresh- or brackish-water fish in which the larvae are found o Thus, the laboratory diagnosis for intestinal capillariasis is presence of eggs in stool

Diagnostic stage: Eggs in stool Infective stage: Larvae in fish that is eaten

Life Cycle 1—Man ingest raw fish harboring infective stage larvae  2—In 2 weeks, larvae develop into mature male worms and atypical females in the jejunum  3—Larvae are produced by the atypical/larviparous females

AsturiaNOTES by RAsturiano UST-FMS A-2019: #TheElusiveDoktora Page 7 of 11 August 12, 2015. Lecturer: Dr. O. Ng—downloadable (for free!) at: www.theelusivedokora.wordpress.com Lecture 1: Nematodes 1 #AsturiaNOTES Parasitology: Trichuris trichiura, Trichinella spiralis, Capillaria philippinensis, and Enterobius Vermicularis

 4—In 2 or more weeks, larvae develop into male adult and typical females  5—Eggs are laid by the typical females  6—Eggs and larvae are passed out in the feces  7—Eggs are embryonated in fresh water in 3-5 days  8—Embryonated eggs are ingested by fresh/brackish water fish  9—In fish, the eggs hatch and develop in the GIT into the infective larvae within 3 week  10—back to #1

Note: Capillaria philippinensis has the capability to autoinfect the host with even if the parasite does no cycle in the fish.  This happens when there are infective larvae in the intestines

Diagnosis  Presence of: o Eggs . Can be readily seen in fecal smear via the concentration technique using: 1 Acid ether 2 Formalin ether o Larvae o Adult worms in the stool

Pathogenesis  NOT ALL patients present with eosinophilia  The intestinal villi are blunted, flattened, or completely obliterated with atrophy of Crypts of Lieberkuhn and an inflammatory submucosal infiltrate (infiltrate is composed of Plasma Cells, Macrophages, and Lymphocytes) o It can be expected that the destruction of intestinal villi will render the host with diminished capable to absorb nutrients (malabsorption)\  Other manifestations: o Malabsorption of fats and sugar o Protein-losing enteropathy o HypoK, Hypocalcemia, and Hypocarotenemia (Decreased KCC) o Hypoproteinemia

Symptoms  BAD! o Borborygmi o Abdominal pain o Diarrhea  If the infection is untreated: o Weight loss o Dehydration o Malaise o Anorexia o Vomiting o Anasarca—Generalized edema with accumulation of serum in the connective tissue

AsturiaNOTES by RAsturiano UST-FMS A-2019: #TheElusiveDoktora Page 8 of 11 August 12, 2015. Lecturer: Dr. O. Ng—downloadable (for free!) at: www.theelusivedokora.wordpress.com Lecture 1: Nematodes 1 #AsturiaNOTES Parasitology: Trichuris trichiura, Trichinella spiralis, Capillaria philippinensis, and Enterobius Vermicularis

o Muscle wasting o Cachexia  Death due to intestinal capillariasis is due to: o Electrolyte loss o Heart Failure o Septicemia secondary to bacterial infection

Treatment  Mebendazole  Albendazole

Epidemiology  Male is affected twice than females  Peak age: 20-49 years old

Prevention and Control  Changing the eating habits of consuming raw and uncooked fish

D. Enterobius vermicularis

 Common name: Pinworm/Seatworm  Habitat: o Cecum o Appendix o Adjacent portion of the ascending colon o Ileum  Causative agent for: Enterobiasis

Morphology  Color: Whitish to Brownish  Shape: Spindle-shaped  Size: o Small worms o Again, Female is BIGGER  Anterior end: o With a pair of lateral cuticular expansions known as lateral wings or cephalic alae o Another feature of pinworm adult: Presence of posterior esophageal bulb  Posterior end: o Female—long, sharp, and pointed o Male—ventrally curved . Has a single conspicuous copulatory spicule but lack gubernaculum

Eggs  Shape: elongated, ovoid, and flattened on ventral side giving a letter-D shape  Has an egg shell: o Layers:

AsturiaNOTES by RAsturiano UST-FMS A-2019: #TheElusiveDoktora Page 9 of 11 August 12, 2015. Lecturer: Dr. O. Ng—downloadable (for free!) at: www.theelusivedokora.wordpress.com Lecture 1: Nematodes 1 #AsturiaNOTES Parasitology: Trichuris trichiura, Trichinella spiralis, Capillaria philippinensis, and Enterobius Vermicularis

. Outer—Thick hyaline, albuminous shell . Inner—Embryonic lipoidal membrane

Life Cycle  1—Mature egg is ingested by human  2—Eggs hatch in duodenum  3—Larva develops to maturity in the small intestine  4—Then it proceeds to its final habitat in the large intestine

However  5—Some gravid females migrate out of the anus and deposits mature (infective) eggs in the perianal and perineal regions  6—Some of the eggs remain around the anus, others become detached and lodge in clothes and bed linen and from there, they are spread by air currents  7—Hand scratching of the perianal area due to the itchiness caused by the eggs can be a source of infection when the hand used to scratch is used for eating going back to #1

Diagnosis  History of pruritus in the perianal region  Use of perianal cellulose or scotch tape swab o Used for the recovery of D-shaped embryonated egg o Since, oviposition take place at night, the best time to take the swab is right after the patients awakens or before bath

Pathogenesis

The pathogenesis of this parasite has three parts:  Pathology at the site of attachment of the worm o Minute ulceration and abscesses develop in cecal mucosa  Pathology due to egg deposition in the perianal region o Intense itching or pruritis in the perianal region resulting to scratching of the area until it is scarified o Can also result in: . Hemorrhages . Eczema—an inflammatory condition of the skin characterized by redness, itching, and oozing vesicular lesion which become scaly, crusted, and hardened . Bacterial infection  Pathology caused by migrating worms o The migration may go beyond the perianal region and may cause: . Vulvovaginitis . Salphingitis

Epidemiology  Women are more infected than men  Children are more infected than adults  Infection may occur through:

AsturiaNOTES by RAsturiano UST-FMS A-2019: #TheElusiveDoktora Page 10 of 11 August 12, 2015. Lecturer: Dr. O. Ng—downloadable (for free!) at: www.theelusivedokora.wordpress.com Lecture 1: Nematodes 1 #AsturiaNOTES Parasitology: Trichuris trichiura, Trichinella spiralis, Capillaria philippinensis, and Enterobius Vermicularis

o Hand to mouth transmission or from scatching the perianal region or from handling contaminated objects—most common form of transmission o Inhalation of airborne egg in dust o Retrograde infection through the anus  Crowded indoor living and temperate climate are factors for infection

Treatment  Mebendazole  Pyrantel pamoate

Prevention  Personal hygiene  Finger nail should be cut short  Handwashing after using the toilet or before meal  Bed linens and clothing of infected person should be sterilized by boiling

-end- References

1. Markell and Voge’s Medical Parasitology (9th edition) 2. Lecture notes by RAsturiano from the lecturer

Downloadable for free at: www.theelusivedoktora.wordpress.com For any corrections you may find, content or otherwise, email me at: [email protected]

-THANKS-

AsturiaNOTES By RAsturiano #TheElusiveDoktora

AsturiaNOTES by RAsturiano UST-FMS A-2019: #TheElusiveDoktora Page 11 of 11 August 12, 2015. Lecturer: Dr. O. Ng—downloadable (for free!) at: www.theelusivedokora.wordpress.com