Intestinal Nematodes

Question 1

Characteristics of intestinal nematodes

Answer 1

1. They are round
2. unsegmented helminths
3. bilateral symmetry
4. fully functional digestive tract
5. usually long and cylindrical
6. vary from a few millimeters to over a meter long
7. Tapered at both ends
8. Those in humans have separate sexes
9. Males usually smaller than females

Question 2

What is Direct infection?

Answer 2

This means that once the egg is ingested and the internal larva has emerged, it develops within the intestinal tract into the adult form

Question 3

Discuss indirect infection

Answer 3

Indirect- there is extensive migration throughout the body prior to adult worm maturation and egg production

Question 4

Most prevalent nematodes in Nigeria

Answer 4

Ascaris lumbricoides 54%
Trichuris trichuria 43.7%
Necator Americanus 42.7%
Strongyloides Stercoralis 33%

Question 5

How many people are estimated to carry nematode infections and what are the risks and morbidities?

Answer 5

World Health Organization (WHO) estimates suggest that over 3.5 billion people carry nematode infections

Risks:
HIV or other immunosuppressive ailments
Poverty!!
Poor sanitation
Climatic

Morbidity: blood loss, malnutrition, and intestinal blockage

Question 6

What are some Parasitic factors for clinical effect?

Answer 6

1. strain of parasite and adaptation to a human host.
2. number of parasites (parasite load).
3. site(s) occupied in the body

Question 7

GI Nematodes of clinical importance

Answer 7

• Enterobius vermicularis (pinworm)
• Trichuris trichiura (whipworm)
• Ascaris lumbricoides (human roundworm)
• Ancylostoma duodenale and Necator americanus (human hookworms)
• Strongyloides stercoralis (human threadworm)
• Trichinella spiralis

Question 8

What is the name of the new world hookworm?

Answer 8

Necator americanus

Question 9

Length of ascaris lumbricoides

Answer 9

females measure 20 to 35 cm long, and males are 15 to 31 cm long

Question 10

Describe the life cycle of ascaris lumbricoides

Answer 10

1. Humans, ingest egg in food contaminated with human feces
2. Eggs move to the duodenum and stomach, then they hatch and release, larvae
3. Larvae migrates through the intestinal wall and undergo molting. It is carried to the right heart, into the pulmonary circulation (in 10 days)
4. Larvae breaks into the alveoli land migrate into the bronchi into the trachea to the pharynx, and then swallow then re-entered the intestine, larvae mature and mate in small intestine in adults and many eggs are produced by the female 60 million in her lifespan
5. eggs are released into stool
6. become embryonated in warm moist soil. Ingestion of eggs complete lifecycle

Question 11

Incubation period of ascaris lumbricoides
When do fertilized eggs become infective?

Answer 11

The entire developmental process from egg ingestion to egg passage from the adult female takes from 8 to 12 weeks.

Often only female worms are recovered from the intestine.

Fertilized eggs become infective within 2 weeks if they are in moist, warm soil, where they may remain viable for months or even years

Question 12

Describe the fertilized and unfertilized ascaris egg

Answer 12

The fertilized egg is broadly oval, more rounded, with a thick, mammillated coat, usuallybile-stained a golden brown.

These eggs measure up to 75μm long and 50 μm wide.
Unfertilized eggs are usually more oval, measure up to 90 μm long, and may have apronounced mammillated coat or an extremely minimal mammillated layer.
Decorticate

Question 13

What is the Pathology of ascaris?

Answer 13

Pathology-Ascariasis
the host immune response- (asymptomatism), effects of larval migration, mechanical effects of the adult worms, and nutritional deficiencies due to the presence of the adult worms
Ascaris Pnemonitis
transient pulmonary infiltrates associated with peripheral eosinophilia -Loeffler’s syndrome
Asthma and urticaria may continue during the intestinal phase of ascariasis
Rarely hepatic ascariasis
Worm migration may occur as a result of stimuli such as fever (usually over 38.9°C), the use of general anesthesia,or steroids.
This migration may result in intestinal blockage
bowel perforation and peritonitis, anal passage of worms, vomiting, and abdominal pain.

Question 14

Diagnosis of ascariasis

Answer 14

Larval migration phase- sputum or gastric washings
Intestinal phase- eggs (iodine/Saline wet mount) or adult worms in stool
Radiology- trolley-car lines
bowel obstruction, biliary or pancreaticduct blockage, appendicitis, or peritonitis
Acute abdomen

Question 15

Diagnosis of ascariasis

Answer 15

Larval migration phase- sputum or gastric washings
Intestinal phase- eggs (iodine/Saline wet mount) or adult worms in stool
Radiology- trolley-car lines
bowel obstruction, biliary or pancreaticduct blockage, appendicitis, or peritonitis
Acute abdomen

Question 16

Treatment, prevention, complications, prognosis of ascariasis

Answer 16

Treatment- Adult worm killers
Albendazole or mebendazole -drug of choice
ivermectin and pyrantel pamoate (pregnancy)
Levimasole

Prevention
Sanitation
Faeces as fertilizers

Complications
Low weight
Anaemia

Prognosis
Good but reinfection

Question 18

What is the nemaode with High prevalence in children

Answer 18

Enterobius vermicularis aka pin worm

Question 19

pinworm morphology

Answer 19

Female pinworms (about 10 millimeters in length) have a slender, pointed PIN posterior end. Males are approximately 3 millimeters in length and have a curved posterior end

Question 20

Mode of transmission of Enterobius vermicularis and how does it migrate?

Answer 20

After fertilization of the female worms, the males usually die and may be passed out in the stool
the female migrates down the colon and out of the anus, where they deposit eggs on the perianal and perineal skin
Vaginal migration sometimes
eggs are fully embryonated and infective within a few hours
transmission is often attributed to the ingestion of infective eggs by nail biting and inadequate hand washing

Question 21

Life Cycle of enterobius vermicularis

Question 22

Pathology of Enterobius vermicularis and clinical manifestation

Answer 22

Pathology: Enterobiasis
Asymptomatic
PRURITUS via migration of the female worms from the anus onto the perianal skin before egg deposition ……. Hypersensitivity reaction of the eggs
Women and children are more predisposed to symptomatism
+/- eosinophilia
nervousness, insomnia, nightmares, and convulsions
unexplained eosinophilic enterocolitis

Question 23

Diagnosis of Enterobius vermicularis

Answer 23

Diagnosis
May be clinical; anal itching, irritability and insomnia
Confirmed laboratory by demonstrating the presence of eggs or adult worms
perianal and perineal skin with cellulose tape (Scotch tape) 4X overnight
The tape is transferred to a glass slide and examined under the microscope for the presence of eggs or adult worms
Stool sampling rarely

Question 24

Treatment of enterobius vermicularis

Answer 24

Treatment
albendazole or mebendazole
ivermectin or pyrantel pamoate
Sanitation and good hygiene

Question 25

Which nematode is usually seen with Ascaris spp.

Answer 25

Trichuris trichiura aka whip worm

Question 26

Type of life cycle of whip worm

Answer 26

Direct life cycle

Question 27

Morphology of Trichuris Trichuria

Answer 27

Adult female whipworms are approximately 30–50 millimeters in length; adult male worms are smaller 360° coil at the caudal extremity Adult whipworms inhabit the colon, where male and female worms mate

Question 28

Life Cycle of Trichuris Trichuria

Question 29

Pathology of Trichuris trichuria

Answer 29

Pathology- Trichuriasis Asymptomatic The head portion of the worm is very thin and is embedded in the mucosa, while the posterior end is much thicker and lies free in the lumen of the large intestine Punctate haemorrhages

Question 30

Clinical manifestations of trichuriasis What is the dreaded complication?

Answer 30

Intestinal manifestations-worm burden, the length of the infection, and the age and overall health status of the host Lower abdominal pain, distention, and diarrhea chronic dysentery-like syndrome if they have a massive infestation leading to anemia and growth retardation. Severe infection may lead to profuse bloody diarrhea, cramps, tenesmus, urgency, and **RECTAL PROPLAPSE (dreaded complication)** the appendix, causing appendicitis Hypochromic anaemia-blood loss

Question 31

Dreaded complications of Trchuriasis

Answer 31

rectal prolapse

Question 32

List examples of hookworms

Answer 32

Ancylostoma duodenale, Necator americanus, and Ancylostoma ceylanicum

Question 33

Epidemology of hookworm

Answer 33

An estimated 700 million to 900 million people worldwide are infected with hookworm (mostly Ancylostoma duodenale), 0.2% of whom suffer fromsevere anemia

Question 34

Morphology of hookworm

Answer 34

Adult fem males measure 7 to 11 mm long The adult Ancylostoma worm tends to be larger than the Necator worm

Question 35

Life Cycle of hookworm

Question 36

Special characteristics of hookworms

Answer 36

Proteolytic enzymes for penetration Optimal pH Life cycle similar to Ascaris when in the intestines This worm attaches to the intestine and feeds on the blood from the capillary-rich lamina propria of the bowel

Question 37

Pathology of Hookworm and clinical manifestation

Answer 37

Pathology----Hookworm infection Worm burden predicts events Skin penetration Ground itch----may become infected (erythema and intense pruritus ) Pneumonitis Intestinal phase Necrosis of tissue and blood ingestion Necator---0.03ml/day; Ancylostoma---0.15-0.2ml/day Clinically manifested as fatigue, nausea, vomiting, abdominal pain, diarrhea with black to red stools (depending on the level of blood loss), weakness, and pallor In chronic infections- iron deficiency anemia (microcytic, hypochromic) Loefflers Syndrome

Question 38

Diagnosis of hookworms

Answer 38

Eggs in the stool---non-distinguishable amidst species

Question 39

Treatment of hookworms

Answer 39

mebendazole, pyrantel pamoate, and albendazole Iron replacement Mangement of co-morbidities

Question 40

Life cycle of Strongyloides stercoralis

Question 41

Pathology of Strongyloides stercoralis

Answer 41

Pathology- Strongyloidiasis Point of entry- skin irritation and pruritus in the form of low-grade chronic dermatitis , **Larva currens** The intestinal manifestations vary from few to no symptoms in light infections to severe necrotizing bowel disease in heavy infections **DDx PUD, crohn’s (eosinophilic granulomatous enterocolitis) (severe diarrhea, abdominal pain, gastrointestinal bleeding, nausea, vomiting) Loeffler’s pneumonia**

Question 41

How is strongyloidiasis disseminated?

Answer 41

Disseminated Strongyloides infection---organic Autoinfection Hyperinfection----Immunity problem; steroids and human T-lymphotropic virus type 1 (HTLV-1) infection Gram-negative sepsis

Question 41

Diagnosis of strongyloidiasis

Answer 41

Rhabditiform larva in stool Eggs could be seen in profuse diarrhoea Peripheral Eosinophilia EnteroTest capsule Molecular Serology

Question 42

Clinical manifestation of chronic strongyloidiasis

Answer 42

chronic disease These symptoms include intermittent vomiting, diarrhea, constipation, and loud gurgling GI noises, Anal pruritus, urticaria and larva currens, rashes, recurrent asthma, and nephrotic syndrome have alsobeen associated with.

Question 43

Primary and secondary treatment of Strongyloidiasis

Answer 43

Treatment Ivermectin Thiabendazole Mebendazole Albendazole

Question 44

What is Trichinella spiralis?

Answer 44

Acquired by eating improperly cooked meat infected with the larval stage Mating of adult worms occur in the intestine post-maturation female worms release live larvae larvae penetrate the intestine, circulate in the blood,and eventually encyst in muscle tissue Intestinal symptoms: diarrhea, abdominal pain, and nausea Muscular encystation is the hallmark of Trichinellosis/Trichinosis Tissue nematode!!!!

Question 44

What is Trichostrongylus spp.?

Answer 44

Trichostrongylus spp. Rare in man Similar to hookworm in structure (but nil jaws) and intestinal habitat (nil lung migration) Live embedded in the mucosa of the small intestine Infection in humans is acquired through ingestion of the infective larvae contaminating plant material Clinical effect----Worm burden and intestinal damage

Question 44

Symptoms of Trichostrongylus spp?

Answer 44

Symptoms: Epigastric pain, diarrhea, anorexia, nausea, dizziness, and generalized fatigue or malaise; eosinophilia is usually present Cholecystitis Dx-Egg In stool Tx- pyrantel pamoate, mebendazole, and albendazole

Question 44

Ascaris lumbricoides has a migratory phase through the lungs true or false?

Answer 44

True

Question 45

Ascaris lumbricoides first phase is the lung phase true or false?

Answer 45

False Intestinal

Question 45

Ascaris lumbricoides moves from the lungs to the large intestine true or false?

Answer 45

False It moves from the lungs to the trachea

Question 46

Coughing, mental regression, and spiked eosinophilia are signs of what?

Answer 46

Loefflers Syndrome

Question 47

Pneumonitis is secondary to what?

Answer 47

Loefflers Syndrome

Question 48

In testing for eosinophilia what type of blood count would you request?

Answer 48

Five parts blood count not three part because three parts would not show eosinophils

Question 49

Enterobius vermicularis has a direct life cycle true or false?

Answer 49

True

Question 50

Before diagnosing enterobiasis where insomnia is seen in a child a good physician should first rule out what?

Answer 50

OSAS Obstructive sleep apnea syndrome due to adenoids

Question 51

What are the phases of pathology for ascaris lumbricoides ?

Answer 51

Lung and intestine

Question 52

Stercoralis is sophisticated in pathogenesis True or false

Answer 52

True

Question 53

Stercoralis is sophisticated in pathogenesis True or false

Answer 53

True

Question 54

Stercoralis has in vivo instantaneous effect in immunocompetent, individuals true or false?

Answer 54

False Immunosuppressed

Question 55

Larva currens is a characteristic of what

Answer 55

Dermatitis in strongyloides

Question 56

What is usually topical for lava currens?

Answer 56

Thiabendazole