Pinworm, Whipworm, Hookworm and Roundworm Infestations
Session 40: Pinworm, Whipworm, Hookworm and Roundworm Infestations
Total Session Time: 120 minutes
Pre-requisites
Students Learning Tasks
By the end of this session students are expected to be able to:
common diseases caused by helminths (, pinworm, whipworm, hookworm,
intestinal roundworm, filarial worm)
hookworm, intestinal roundworm, filarial worm)
•
Resources Needed:
SESSION OVERVIEW
|Step |Time |Activity/ |Content |
| | |Method | |
|1 |5 minutes |Presentation |Introduction, Learning Tasks |
|2 |25 minutes |Presentation |Pinworm infestation (Enterobiasis)|
|3 |25 minutes |Presentation |Whipworm infestation |
| | | |(Trichuriasis) |
|4 |25 minutes |Presentation |Hookworm infestation |
| | | |(Ancylostomiasis) |
|5 |30 minutes |Presentation |Roundworm infestation (Ascariasis)|
|6 |5 minutes |Presentation |Key Points |
| 7|5 minutes |Presentation |Evaluation |
SESSION CONTENTS
STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)
READ or ASK students to read the learning tasks and clarify
ASK students if they have any questions before continuing
STEP 2: Pinworm Infestation –Enterobiasis (15 minutes)
Cause and Transmission
disease caused by the pinworm Enterobius vermicularis.
spindle-shaped with a large, bulbar esophagus
or indirectly via contaminated hands or objects such as clothes, toys,
and bedding.
perianal skin.
intestines.
o Eggs are deposited on perianal folds. Self-infection occurs by
transferring infective eggs to the mouth with hands that have
scratched the perianal area.
o Person-to-person transmission can also occur through handling of
contaminated clothes or bed linens.
o Enterobiasis may also be acquired through surfaces in the
environment that are contaminated with pinworm eggs (e.g. curtains,
carpeting).
o Some small number of eggs may become airborne and inhaled. These
would be swallowed and follow the same development as ingested
eggs.
o Following ingestion of infective eggs, the larvae hatch in the
small intestine and the adults establish themselves in the colon
o The time interval from ingestion of infective eggs to oviposition
by the adult females is about one month.
o The life span of the adults is about two months. Gravid females
migrate nocturnally outside the anus and oviposit while crawling on
the skin of the perianal area.
o The larvae contained inside the eggs develop (the eggs become
infective) in 4 to 6 hours under optimal conditions.
o Retroinfection, or the migration of newly hatched larvae from the
anal skin back into the rectum, may occur
[pic]
o Enterobiasis is most common in children, who usually present with
o Antihelminthic drugs
o Preventive measures include;
region and changing nightclothes
STEP 3: Whipworm Infestation –Trichuriasis (30 minutes)
Cause and Transmission
intestine by Trichuris trichiura (also known as the human whipworm),
which is an intestinal parasitic nematode.
the colon and rectum. People infected with whipworm can suffer light
or heavy infections.
"whip-worms" because they have a broad short posterior end and a very
long narrow whip-like anterior end
ingestion of eggs with contaminated food, water or soil.
o The unembryonated eggs are passed with the stool. In the soil, the
eggs develop into a 2-cell stage, an advanced cleavage stage, and
then they embryonate; eggs become infective in 15 to 30 days.
o After ingestion (soil-contaminated hands or food), the eggs hatch
in the small intestine, and release larvae that mature and
establish themselves as adults in the colon.
o The adult worms (approximately 4 cm in length) live in the cecum
and ascending colon. The adult worms are fixed in that location,
with the anterior portions threaded into the mucosa.
o The females begin to oviposit 60 to 70 days after infection. Female
worms in the cecum shed between 3,000 and 20,000 eggs per day. The
life span of the adults is about 1 year.
[pic]
Signs and Symptoms
occasionally rectal prolapse
Treatment and Prevention
o Albendazole
o Mebendazole
o Sanitary disposal of faeces
o Effective sewage disposal systems
o Personal hygiene e.g. washing hands
o Thorough washing of vegetables, salads and fruits with clean water
prior to consumption
STEP 4: Hookworm Infestation –Ancylostomiasis (30 minutes)
Ancylostomiasis
infestation of the small intestine with Ancylostoma duodenale or
Necator americanus. It is one of the main causes of anaemia in the
tropics which is also the major clinical feature.
o Eggs are passed in the stool and under favorable conditions
(moisture, warmth, shade), larvae hatch in 1 to 2 days to form
rhabditiform larvae.
o The larvae grow in the feces and/or the soil and after 5 to 10 days
(and two molts) they become filariform (third-stage) larvae that
are infective
o These infective larvae can survive 3 to 4 weeks in favorable
environmental conditions.
o On contact with the human host, the larvae penetrate the skin and
are carried through the blood vessels to the heart and then to the
lungs.
o They penetrate into the pulmonary alveoli, ascend the bronchial
tree to the pharynx, and are swallowed.
o The larvae reach the small intestine, where they reside and mature
into adults.
o Adult worms live in the lumen of the small intestine, where they
attach to the intestinal wall with resultant blood loss by the
host.
o Most adult worms are eliminated in 1 to 2 years, but the longevity
may reach several years.
o Some A. duodenale larvae, following penetration of the host skin,
can become dormant (in the intestine or muscle)
o In addition, infection by A. duodenale may probably also occur by
the oral and transmammary route.
o N. americanus, however, requires a transpulmonary migration phase.
[pic]
o The majority of patients are asymptomatic
o Ground itch” (itching at the site of invasion by the larvae)
o Pneumonitis, cough, dyspnea, and, occasionally, hemoptysis
o Anorexia
o Anaemia
o Fever, diarrhea, abdominal discomfort, weight loss, nausea and
vomiting, spleen and liver enlargement, and edema.
o Children may suffer from mental, physical, and sexual retardation.
o Anthelminthic medications
o Infections are generally treated for 1-3 days.
o Hookworm can be prevented by;
improved diet, including administration of iron.
STEP 5: Roundworm Infestation –Ascariasis (30 minutes)
Cause and Transmission
o A. lumbricoides belongs to the phylum Nematoda
o They are mainly free living and ubiquitous
o A. lumbricoides is the largest and most common intestinal nematode
of humans
o A. lumbricoides is found in the small intestine, particularly the
jejunum. Females produce as many as 240,000 eggs per day and as
many as 65 million in a lifetime
o Ascariasis is transmitted by the faecal-oral route through
consumption of drinks (water) or food contaminated with faeces
containing eggs of A. lumbricoides.
o Life cycle
which are passed with the feces. Unfertilized eggs may be
ingested but are not infective. Fertile eggs embryonate and
become infective after 18 days to several weeks, depending on
the environmental conditions (optimum: moist, warm, shaded
soil).
the intestinal mucosa, and are carried via the portal, then
systemic circulation to the lungs.
penetrate the alveolar walls, ascend the bronchial tree to the
throat, and are swallowed.
worms. Between 2 and 3 months are required from ingestion of
the infective eggs to oviposition by the adult female. Adult
worms can live 1 to 2 years
[pic]
o Cough
o Low-grade fever
o Passing worms in stool
o Shortness of breath
o Skin rash
o Stomach pain
o Vomiting or coughing up worms
o Worms leaving the body through the nose or mouth
o Treatment includes medicines that paralyze or kill intestinal
parasitic worms.
o If there is a blockage of the intestine caused by a large number of
worms, endoscopy may be used to remove the worms. In rare cases,
surgery is needed.
o People treated for roundworms should be checked again in 3 months.
worm. If eggs are present, treatment should be given again
o Anthelminthic medications
o Infections are generally treated for 1-3 days
o Preventive measures include;
toilet and before eating
before eating, particularly those that have been grown in soil
that has been fertilized with manure
o Thorough washing of vegetables, salads and fruits with clean water
prior to consumption
STEP 6: Key Points (5 minutes)
Enterobius vermicularis.
or Necator americanus. Ascariasis is caused by Ascaris lumbricoides
environmental hygiene.
STEP 7: Evaluation (5 minutes)
References
Hugo and Russell (2011), Pharmaceutical Microbiology 8th Edition, Willey-
Blackwel publications
Karen C. Carroll et al (2013); Jawetz, Melnick and Adelberg’s Medical
Microbiology 26th Ed. McGraw Hill Co. Inc.
Greenwood et al (2012); Medical Microbiology, 18th edition Churchill
Livingstone
Session 40: Pinworm, Whipworm, Hookworm and Roundworm Infestations
Total Session Time: 120 minutes
Pre-requisites
Students Learning Tasks
By the end of this session students are expected to be able to:
common diseases caused by helminths (, pinworm, whipworm, hookworm,
intestinal roundworm, filarial worm)
hookworm, intestinal roundworm, filarial worm)
•
Resources Needed:
SESSION OVERVIEW
|Step |Time |Activity/ |Content |
| | |Method | |
|1 |5 minutes |Presentation |Introduction, Learning Tasks |
|2 |25 minutes |Presentation |Pinworm infestation (Enterobiasis)|
|3 |25 minutes |Presentation |Whipworm infestation |
| | | |(Trichuriasis) |
|4 |25 minutes |Presentation |Hookworm infestation |
| | | |(Ancylostomiasis) |
|5 |30 minutes |Presentation |Roundworm infestation (Ascariasis)|
|6 |5 minutes |Presentation |Key Points |
| 7|5 minutes |Presentation |Evaluation |
SESSION CONTENTS
STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)
READ or ASK students to read the learning tasks and clarify
ASK students if they have any questions before continuing
STEP 2: Pinworm Infestation –Enterobiasis (15 minutes)
Cause and Transmission
disease caused by the pinworm Enterobius vermicularis.
spindle-shaped with a large, bulbar esophagus
or indirectly via contaminated hands or objects such as clothes, toys,
and bedding.
perianal skin.
intestines.
o Eggs are deposited on perianal folds. Self-infection occurs by
transferring infective eggs to the mouth with hands that have
scratched the perianal area.
o Person-to-person transmission can also occur through handling of
contaminated clothes or bed linens.
o Enterobiasis may also be acquired through surfaces in the
environment that are contaminated with pinworm eggs (e.g. curtains,
carpeting).
o Some small number of eggs may become airborne and inhaled. These
would be swallowed and follow the same development as ingested
eggs.
o Following ingestion of infective eggs, the larvae hatch in the
small intestine and the adults establish themselves in the colon
o The time interval from ingestion of infective eggs to oviposition
by the adult females is about one month.
o The life span of the adults is about two months. Gravid females
migrate nocturnally outside the anus and oviposit while crawling on
the skin of the perianal area.
o The larvae contained inside the eggs develop (the eggs become
infective) in 4 to 6 hours under optimal conditions.
o Retroinfection, or the migration of newly hatched larvae from the
anal skin back into the rectum, may occur
[pic]
o Enterobiasis is most common in children, who usually present with
o Antihelminthic drugs
o Preventive measures include;
region and changing nightclothes
STEP 3: Whipworm Infestation –Trichuriasis (30 minutes)
Cause and Transmission
intestine by Trichuris trichiura (also known as the human whipworm),
which is an intestinal parasitic nematode.
the colon and rectum. People infected with whipworm can suffer light
or heavy infections.
"whip-worms" because they have a broad short posterior end and a very
long narrow whip-like anterior end
ingestion of eggs with contaminated food, water or soil.
o The unembryonated eggs are passed with the stool. In the soil, the
eggs develop into a 2-cell stage, an advanced cleavage stage, and
then they embryonate; eggs become infective in 15 to 30 days.
o After ingestion (soil-contaminated hands or food), the eggs hatch
in the small intestine, and release larvae that mature and
establish themselves as adults in the colon.
o The adult worms (approximately 4 cm in length) live in the cecum
and ascending colon. The adult worms are fixed in that location,
with the anterior portions threaded into the mucosa.
o The females begin to oviposit 60 to 70 days after infection. Female
worms in the cecum shed between 3,000 and 20,000 eggs per day. The
life span of the adults is about 1 year.
[pic]
Signs and Symptoms
occasionally rectal prolapse
Treatment and Prevention
o Albendazole
o Mebendazole
o Sanitary disposal of faeces
o Effective sewage disposal systems
o Personal hygiene e.g. washing hands
o Thorough washing of vegetables, salads and fruits with clean water
prior to consumption
STEP 4: Hookworm Infestation –Ancylostomiasis (30 minutes)
Ancylostomiasis
infestation of the small intestine with Ancylostoma duodenale or
Necator americanus. It is one of the main causes of anaemia in the
tropics which is also the major clinical feature.
o Eggs are passed in the stool and under favorable conditions
(moisture, warmth, shade), larvae hatch in 1 to 2 days to form
rhabditiform larvae.
o The larvae grow in the feces and/or the soil and after 5 to 10 days
(and two molts) they become filariform (third-stage) larvae that
are infective
o These infective larvae can survive 3 to 4 weeks in favorable
environmental conditions.
o On contact with the human host, the larvae penetrate the skin and
are carried through the blood vessels to the heart and then to the
lungs.
o They penetrate into the pulmonary alveoli, ascend the bronchial
tree to the pharynx, and are swallowed.
o The larvae reach the small intestine, where they reside and mature
into adults.
o Adult worms live in the lumen of the small intestine, where they
attach to the intestinal wall with resultant blood loss by the
host.
o Most adult worms are eliminated in 1 to 2 years, but the longevity
may reach several years.
o Some A. duodenale larvae, following penetration of the host skin,
can become dormant (in the intestine or muscle)
o In addition, infection by A. duodenale may probably also occur by
the oral and transmammary route.
o N. americanus, however, requires a transpulmonary migration phase.
[pic]
o The majority of patients are asymptomatic
o Ground itch” (itching at the site of invasion by the larvae)
o Pneumonitis, cough, dyspnea, and, occasionally, hemoptysis
o Anorexia
o Anaemia
o Fever, diarrhea, abdominal discomfort, weight loss, nausea and
vomiting, spleen and liver enlargement, and edema.
o Children may suffer from mental, physical, and sexual retardation.
o Anthelminthic medications
o Infections are generally treated for 1-3 days.
o Hookworm can be prevented by;
improved diet, including administration of iron.
STEP 5: Roundworm Infestation –Ascariasis (30 minutes)
Cause and Transmission
o A. lumbricoides belongs to the phylum Nematoda
o They are mainly free living and ubiquitous
o A. lumbricoides is the largest and most common intestinal nematode
of humans
o A. lumbricoides is found in the small intestine, particularly the
jejunum. Females produce as many as 240,000 eggs per day and as
many as 65 million in a lifetime
o Ascariasis is transmitted by the faecal-oral route through
consumption of drinks (water) or food contaminated with faeces
containing eggs of A. lumbricoides.
o Life cycle
which are passed with the feces. Unfertilized eggs may be
ingested but are not infective. Fertile eggs embryonate and
become infective after 18 days to several weeks, depending on
the environmental conditions (optimum: moist, warm, shaded
soil).
the intestinal mucosa, and are carried via the portal, then
systemic circulation to the lungs.
penetrate the alveolar walls, ascend the bronchial tree to the
throat, and are swallowed.
worms. Between 2 and 3 months are required from ingestion of
the infective eggs to oviposition by the adult female. Adult
worms can live 1 to 2 years
[pic]
o Cough
o Low-grade fever
o Passing worms in stool
o Shortness of breath
o Skin rash
o Stomach pain
o Vomiting or coughing up worms
o Worms leaving the body through the nose or mouth
o Treatment includes medicines that paralyze or kill intestinal
parasitic worms.
o If there is a blockage of the intestine caused by a large number of
worms, endoscopy may be used to remove the worms. In rare cases,
surgery is needed.
o People treated for roundworms should be checked again in 3 months.
worm. If eggs are present, treatment should be given again
o Anthelminthic medications
o Infections are generally treated for 1-3 days
o Preventive measures include;
toilet and before eating
before eating, particularly those that have been grown in soil
that has been fertilized with manure
o Thorough washing of vegetables, salads and fruits with clean water
prior to consumption
STEP 6: Key Points (5 minutes)
Enterobius vermicularis.
or Necator americanus. Ascariasis is caused by Ascaris lumbricoides
environmental hygiene.
STEP 7: Evaluation (5 minutes)
References
Hugo and Russell (2011), Pharmaceutical Microbiology 8th Edition, Willey-
Blackwel publications
Karen C. Carroll et al (2013); Jawetz, Melnick and Adelberg’s Medical
Microbiology 26th Ed. McGraw Hill Co. Inc.
Greenwood et al (2012); Medical Microbiology, 18th edition Churchill
Livingstone
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