Parasitic Diseases Flashcards
(131 cards)
1
Q
Define parasite and parasitic diseases
A
Parasite = an organism that lives in another organism called a host.
-They thrive to the detriment of the host.
Parasitic disease = infectious diseases caused or transmitted by a parasite.
2
Q
List the 3 main types of parasites that cause parasitic disease
A
- Protozoa
- Helminths
- Ectoparasites
3
Q
List the ways parasites can infect humans
A
- Vector borne
- Ingestion
- Inhalation
- Penetration of skin
- Penetration of eyes
- Sexual contact
4
Q
List the risk factors for parasitic infection
A
- Walking barefoot
- Inadequate disposal of feces
- Lack of hygiene
- Close contact with someone carrying a parasite
- Insect bites
- Eating undercooked foods
- Unwashed fruits and vegetables
5
Q
List the 4 protozoans
A
- Amoebas
- Flagelletes
- Ciliates
- Sporozoa
6
Q
Define protozoa
A
- Protozoa are single celled organisms that multiply by simple binary division.
- Protozoa can multiply in their human hosts and cause overwhelming infection.
7
Q
What are the 2 morphological forms of protozoa?
A
- Trophozoite
- Cyst
8
Q
Define trophozoite
A
- Feeding and reproducing stage that lives within the host
- Active, infective stage
9
Q
Define cyst
A
Infective form that survives in the environment
10
Q
Define amoebas
A
- Protozoa with no truly defined shape
- Move and acquire food through the use of pseudopodia
- Found in water sources throughout the world
- Few cause disease**
11
Q
Name 2 amoeba
A
- Naegleria fowleri (primary amoebic meningoencephalitis)
2. Acanthamoeba spp. (contact lens contaminant)
12
Q
Etiology of Acanthamoeba spp.
A
- Can cause infections in humans and animals.
- Commonly found in lakes, swimming pools, tap water and heating & air conditioning units.
13
Q
How does infection with Acanthamoeba spp occur?
A
through cuts or scrapes, the conjunctiva, or through inhalation
14
Q
What diseases does Acanthamoeba spp cause?
A
Can cause diseases such as amoebic keratitis and encephalitis.
15
Q
List the 2 morphology of Acanthamoeba spp.
A
- Trophozoite (active and infective)
- Cyst (dormant and environmentally hardy; can survive for years under extreme temperatures and pH)
16
Q
Life Cycle of Acanthamoeba spp.
A
- The trophozoites replicate through mitosis.
- Under less favorable circumstances, the trophozoites become cysts (for survival).
- The trophozoites then enter the body via ulcerated or broken skin or through the lower respiratory tract.
- They then invade the CNS via hematogenous dissemination.
17
Q
What is Acanthamoeba Keratitis?
A
- A rare but serious infection of the eye that can result in permanent visual impairment or blindness.
- In the US, 85% cases occur in contact lens users.
18
Q
Why are contact lens wearers at risk for Acanthamoeba Keratitis?
A
- Hold amoebas onto the eye
- Trapping water
- Using old solution
- Using tap water to clean lens
19
Q
S/sx of Acanthamoeba Keratitis
A
-Pain and redness of the eye
-Foreign body sensation
-Photophobia
–Blurred vision
Excessive tearing
-Pain out of proportion to clinical findings is a classic feature ofAcanthamoebakeratitis; however, especially early in the disease, lack of pain does not preclude the diagnosis.
20
Q
Acanthamoeba Keratitis on physical exam
A
- Conjunctival hyperemia
- Episcleritis
- Scleritis
- Loosening of the corneal epithelium
21
Q
Diagnosis of Acanthamoeba Keratitis
A
- Refer to an ophthalmologist.
- Clinical picture and growth of the amoeba from scraping of the eye.
- They can see the amoeba on confocal microscopy.
22
Q
Tx of Acanthamoeba Keratitis
A
- Topical cationic antiseptic agent such as polyhexamethylene biguanide (0.02%) or chlorhexidine (0.02%) with or without a diamidine such as propamidine (0.1%) or hexamidine (0.1%).
- The duration of therapy may last six months to a year. *
- Pain control can be helped by topical cyclopegic solutions (topical numbing) and oral nonsteroidal medications
23
Q
Prevention of Acanthamoeba Keratitis
A
- Visit your eye care provider for regular eye examinations.
- Wear and replace contact lenses according to the schedule prescribed by your eye care provider.
- Remove contact lenses before any activity involving contact with water, including showering, using a hot tub, or swimming.
- Wash hands with soap and water and dry before handling contact lenses.
- Clean contact lenses according to instructions from your eye care provider and the manufacturer’s guidelines.
- Store reusable lenses in the proper storage case.
24
Q
What is Granulomatous Amoebic Encephalitis (GAE)?
A
- GAE is a rare, usually fatal infection of the CNS caused by Acanthamoeba spp.
- Usually occurs in people with weakened immune systems.
- Usually enter through the skin or lungs and spread to the bloodstream.
25
S/sx of GAE
- Mental status changes
- Loss of coordination
- Double or blurred vision
- Sensitivity to light
- Skin sores
- Other neurologic problems
26
Diagnosis of GAE
- CT or MRI Brain
- Spinal tap
- Biopsy of brain or skin sores
27
Tx of GAE
- Usually combination therapy
| - Multidrug therapy: Miltefosine with one or more antifungal and antibiotics.
28
Etiology of Naegleria fowleri
“Brain eating amoeba”
- Naegleria fowleri produces an acute, and usually lethal infection of the brain called primary amebic meningoencephalitis (PAM).
- Commonly found in warm freshwater, i.e. lakes, rivers, and hot springs.
29
How does Naegleria fowleri infect people?
Infects people when water containing the amoeba enters the body through the nose.
30
Life cycle of Naegleria Fowleri
- Cyst
- Trophozoite- infective stage
- Flagellate (they infect humans or animals by penetrating the nasal tissue and migrating to the brain via the olfactory nerves)
31
S/sx of Naegleria Fowleri
- Symptoms start about 5 days after infection.
- Initial symptoms include: headache, fever, N/V.
- Later symptoms include: neck stiffness, confusion, lack of attention, loss of balance, seizures, hallucinations and coma.
- Disease progresses rapidly and usually causes death within about 5 days.
32
Diagnosis of Naegleria Fowleri
- CSF sample
- Biopsy
- Tissue specimens: immunofluorescence, PCR, amoeba culture.
- Due to rarity of the infection and difficulty in initial detection, about 75% of diagnoses are made postmortem.
33
Tx of Naegleria Fowleri
- Amphotericin B
- Miconazole/fluconazole/ketoconazole and/or rifampin
- Dexamathasone
- Recently an investigational breast cancer and anti-leishmania drug, Miltefosine, has shown some promise in combination with some of these other drugs
34
Define Flagellates
- Protozoa that possess at least one flagellum
| - Number and arrangement of flagella important to determining the species
35
List the Flagellates
- Chagas disease
- African sleeping sickness
- Leishmaniasis
36
Which organism causes Chagas disease?
Trypanosoma cruzi
37
Where is Chagas disease endemic?
Central and South America
38
Transmission of Chagas disease
- Transmission occurs through bites by triatomine bugs.
- After they bite and ingest blood, they defecate on the person.
- The person can become infected if T. cruzi parasites in the bug feces enter the body through mucous membranes or breaks in the skin.
- “Kissing bugs” feed preferentially from the faces/lips
39
What other ways is Chagas disease transmitted?
- Congenital transmission (from a pregnant woman to her baby);
- Blood transfusion;
- Organ transplantation;
- Consumption of uncooked food contaminated with feces from infected bugs; and
- Accidental laboratory exposure
40
S/sx of Chagas disease
| -Acute stage
-Acute- when occurs in endemic areas usually in childhood and asymptomatic.
-1-2 weeks after exposure
Indurated, erythematous lesion “chagoma” appears at the site of parasite entry.
-“Romana sign” inoculation in the conjunctiva, unilateral periocular and palpebral edam with conjunctivitis and preauricular lymphadenopathy.
41
S/sx of Chagas disease
| -Latent stage
- Have parasitological and/or serologic evidence of T. cruzi but have neither symptoms, abnormal physical findings, nor cardiac or GI involvement.
- Many are identified by screening enzyme-linked immunosorbent blood assay(ELISA) and confirmatory radiommunoprecipitation assay (RIPA) when they donate blood.
42
S/sx of Chagas disease
| -Chronic stage
- Develops in 20-40% after a latent phase that may last years to decades.
- Main effects are cardiac and GI***
43
Diagnosis of Chagas disease
- Light microscopy of blood smears or tissues
- Screening serologic test confirmed by a second test- indirect fluorescent antibody (IFA), enzyme immunoassays (EIA)or ELISA and followed by RIPA
- PCR based tests
- Once diagnosed, should get screening EKG and CXR.
- With any cardiac abnormalities get ECHO and with GI symptoms get GI contrast studies or endoscopy.
44
Treatment of Chagas disease
- Antiparasitic treatment is indicated for all cases of acute or reactivated Chagas disease and for chronic Trypanosoma cruzi infection in children up to age 18.
- Congenital infections are considered acute disease.
- Treatment is strongly recommended for adults up to 50 years old with chronic infection who do not already have advanced Chagas cardiomyopathy.
45
Antiparasitic treatment for Chagas disease
- Benznidazole - approved by FDA for use in children 2–12 years of age but is not yet available in U.S. pharmacies.
- Nifurtimox - Nifurtimox is not currently FDA approved
- Both drugs are currently available under investigational protocols from CDC.
46
Prevention of Chagas disease
- Plastering walls and replacing thatched roofs, spraying of houses.
- Travelers -- don’t sleep in adobe dwellings or use bed nets.
47
Which organism causes African Sleeping Sickness?
Trypanosoma brucei
48
Etiology of African Sleeping Sickness
- The insect vector is the tsetse fly*
| - Humans usually infected when bitten by infected tsetse flies
49
What are the 3 stages of Trypanosomiasis?
- Cutaneous
- Hemolymphatic
- CNS
50
S/sx of African Trypanosomiasis
| -Cutaneous
- Papule develops at the site of the tsetse fly bite with a few days to 2 weeks.
- Evolves into a dusky red, painful, indurated nodule (trympanosomal chancre)*
51
S/sx of African Trypanosomiasis
| -Hemolymphatic
- Over several weeks or months with intermittent fever, headaches, rigors, muscle and joint pain and transient facial swelling develops.
- Generalized lymphadenopathy often occurs.
- “Winterbottom sign”- enlarged lymph nodes in the posterior cervical triangle.
52
S/sx of African Trypanosomiasis
| -CNS
- Causes persistent headaches, inability to concentrate, personality changes, daytime somnolence, tremor, ataxia and terminal coma.
- Without treatment patients die in coma of undernutrition or secondary infections.
53
Diagnosis of African Trypanosomiasis
- Light microscopy of blood or other fluid sample
- Chancre fluid, lymph node aspirate, blood, bone marrow aspirate or late stage of infection, CSF.
- Lumbar puncture should be done in all patients**
54
Treatment of African Trypanosomiasis
- Without CNS involvement- Pentamidine, Eflornithine, Suramin
- With CNS involvement- Eflornithine or Melarsoprol
55
Prevention of African Trypanosomiasis
- Avoid endemic areas
- Protection against tsetse flies- wearing substantial wrist and ankle length clothing in neutral colors.
- Tsetse flies can bit through thin clothes
- Skin repellants
56
What is Leishmaniasis?
- Leishmaniasis is caused by the parasite which is transmitted by the bite of the infected female phlebotomine sandflies.
- Affects some of the poorest people on earth, associated with malnutrition, poor housing, a weak immune system and lack of financial resources.
57
Transmission of Leishmaniasis
- Over 20 Leishmania species.
| - Over 90 sandfly species are known to transmit Leishmania parasites.
58
What are the 3 forms of leishmaniasis?
1. Visceral
2. Cutaneous
3. Mucocutaneous
59
Visceral leishmaniasis
- Fatal if left untreated.
- Irregular bouts of fever, weight loss, enlargement of the spleen, liver, and anemia.
- Brazil, East Africa, and SE Asia.
60
Cutaneous leishmaniasis
- MC form
- Skin lesions, mainly ulcers on exposed parts of the body, leaving long scars and serious disability.
- 95% of cases occur in the Americas, Mediterranean, Middle East, and Central Asia.
61
Mucocutaneous leishmaniasis
- Partial or total destruction of the mucous membranes of the nose, mouth and throat**
- >90% occur in Bolivia, Brazil, Ethiopia, and Peru.
62
Diagnosis of leishmaniasis
- Tissue biopsy- lesions, bone marrow
- Culture
- PCR assay
- Rapid serologic test- for detection of antibodies agains the Leishmania donovani species.
63
Treatment of leishmaniasis
- Complicated treatment based on individuals and species/strains.
- Referral to Infectious disease specialist.
- Oral agent Miltefosine FDA approved in 2014 to treat cutaneous, mucosal and visceral leishmaniasis.
64
List the types of helminths
- Fluke
- Tapeworm
- Roundworm
- Hookworms
- Whipworm
- Pinworms
65
Etiology of helminths
- Helminthic infestations are worm-like parasites that infect humans.
- Helminths progress through egg, larval, and adult stages
- Visible to the naked eye in their adult stages.
- In adult form, they cannot multiply in humans.**
66
3 main groups of helminths
1. Flatworms (platyhelminths): Trematodes (flukes) and cestodes (tapeworms)
2. Roundworms (nematodes)
3. Thorny-headed worms (acanthocephalins)
67
Transmission of helminthic parasites
- Fecal- oral transmission of eggs: eggs developing in soil prior to ingestion.
- Completes their life cycle in human intestines and can be transmitted fecal–orally person-to-person and through autoinfection.
- Eating undercooked beef , pork, fish, or crustaceans.
- Direct penetration of skin by larva.
68
Risk factors of helminthic infection
- Low income and poor sanitation.
- Close proximity to contaminated fresh water sources.
- Malnutrition
- Immunocompromised
69
List the 2 kinds of flatworms (platyhelminths)
Flukes (trematodes)
-Schistosoma sp.
Tapeworms (cestodes)
-Taenia
70
What is schistosomiasis?
- Schistosomiasis is caused by blood flukes (trematodes)
- Also known as Bilharzia.
- Schistosoma is the only trematode that invades through the skin.***
71
Etiology of schistosomiasis
- Spreads by coming in contact with contaminated fresh water (ponds, lakes, rivers etc.)
- Second to malaria as the most devastating parasitic disease.
72
What are the 3 main species? What is their similarity?
- Schistosoma haematobium, S. japonicum, and S. mansoni
| - All have similar life cycles involving freshwater snails
73
Life cycle of schistosomiasis
| -prior to penetrating skin
- The parasites that cause schistosomiasis live in certain types of freshwater snails.
- The infectious form, known as cercariae, emerge from the snails and contaminate the water.
- Human gets infected when the cercariae penetrate the skin during contact with the infested water.
74
Life cycle of schistosomiasis
| -after penetrating skin
- During penetration they are transported through the vasculature to the liver.
- In the body, larvae develop into adult schistosomes.
- Adult worms live in the blood vessels where the females release eggs.
75
How does transmission of schistosomiasis occur?
when people suffering from schistosomiasis contaminate freshwater sources with her urine or feces containing the parasite eggs, which hatch in the water.
76
S/sx of schistosomiasis
| -Intestinal
- Abdominal pain
- Diarrhea
- Blood in the stool
- Hepatomegaly -- in advanced cases
77
S/sx of schistosomiasis
| -Urogenital
* *Classic sign: Hematuria**
- In women -- genital lesions, vaginal bleeding, dyspareunia, vulvar nodules.
- In men -- pathology of the seminal vesicles, prostate and other organs.
- Fibrosis of bladder/ureter and kidney damage in advanced cases.
78
Diagnosis of schistosomiasis
- Microscopic examination of stool or urine.
- Stool for S. mansoni or S. japonicum eggs
- Urine for S. haematolgium eggs
- Since eggs tend to be passed intermittently and in small amounts and may not be detected, may need serologic testing.
79
Treatment of schistosomiasis
- Praziquantel 40mg/kg po BID x 1 day- S. mansoni and S. haematobium
- Praziquantel 60mg/kg po TID x 1 day- S. japonicum
- May need to retreat in 2-4 weeks.
- Recheck stool or urine at 1 month post treatment to help confirm successful cure.
80
Prevention of schistosomiasis
- If visiting countries where schistosomiasis occurs, avoid swimming or wading in freshwater.
- Drink safe water.
- Water used for bathing should be brought to a boil for 1 minute to kill any cercaria.
- Vigorous towel drying after an accident brief water exposure to help prevent the parasite penetrating the skin.
81
Define Taeniasis
- Taeniasis is an intestinal infection caused by adult tapeworms.
- Humans become infected by eating raw or undercooked beef or pork.
82
List the 3 species causing taeniasis in humans
1. Taenia solium (pork tapeworm)
2. Taenia saginata (beef tapeworm)
3. Taenia asiatica (Asian tapeworm)
83
Explain the tapeworm life cycle inside the animal.
- Eggs are passed with feces.
- Cattle and pigs ingest contaminated vegetation.
- Once inside the animal, the Taenia eggs hatch in the animal’s intestine and migrate to striated muscle to develop into cysticerci, causing a disease known as cysticercosis.
84
Explain the tapeworm life cycle moving from animal to human.
- Humans become infected by eating raw or undercooked infected beef or pork.
- Ingested cyst (contains embryo worm) attach to the small intestine and develop into adult tapeworms over the course of 2 months.
- The adult tapeworms migrate to the anus and are then passed in the feces.
85
S/sx of taeniasis
- Many infestations are asymptomatic.
- Patients with T. saginata taeniasis often experience more symptoms that those with T. solium because the T. saginata tapeworm is larger in size (up to 10 m).
- Taenia solium tapeworm infections can lead to cysticercosis ,which is a disease that can cause seizures.
- Enters the CNS
- Typical symptoms of taeniasis include vague GI complaints of abdominal pain, cramps, anorexia, nausea, diarrhea, weight loss, or malaise.
86
What is the most visible sx of taeniasis?
- The most visible symptom of taeniasis is the active passing of proglottids (tapeworm segments) through the anus and in the feces.
- In rare cases, tapeworm segments become lodged in the appendix, or the bile and pancreatic ducts.
87
Diff dx for tapeworms
- Gastroenteritis
- Appendicitis
- Chronic anemia
- Irritable bowel disease
- Tumors
88
Diagnosis of tapeworms
- Microscopic stool examinations.
- Examination of 3 stool samples collected on different days is recommended to increase the sensitivity of microscopic methods.
- For larval disease, do imaging.
89
Treatment of tapeworms
- Praziquantel 5-10 mg/kg orally once for adults and 5-10 mg/kg orally once for children.
- -Most often used to treat active taeniasis **
- Niclosamide is an alternative, given at 2 g orally once for adults and 50 mg/kg orally once for children (not available in the US.).
90
List the intestinal roundworms
- Ascaris lumbricoides
| - Enterobius vermicularis
91
List roundworms found in tissue
- Trichinella spiralis
| - Wucheraria bancrofti
92
Etiology of ascariasis
- Ascaris is an intestinal parasite of humans.
| - It is the MC parasitic worm infection in humans worldwide but uncommon in the US.
93
How are humans infected with ascariasis?
- Humans are infected with Ascaris lumbricoides or Ascaris suum, often in food contaminated by human feces.
- It's also possible for eggs to be transferred from your hands to your mouth after touching contaminated soil.
- Can also be infected with A.suum, a closely related roundworm of pigs, after cysts are ingested in food contaminated with feces or larvae are ingested in raw or undercooked pork.
94
Life cycle of Ascaris lumbricoides
- A. lumbricoides eggs hatch in the duodenum and resulting larvae penetrate the wall of the small bowel and migrate via the portal circulation through the liver to the heart and lungs.
- Larvae ascend the bronchial tree and into the oropharynx.
- They are swallowed and returned to the small bowel and they develop into adult worm, which mate and release eggs into the stool.
- Life cycle completed in about 2-3 months and adult worms can live 1-2 years.
95
Sx of Ascariasis
- Ascaris larvae migrating through the lungs may cause cough, wheezing, and occasionally hemoptysis or other respiratory symptoms.
- Some people notice infection when a worm is passed in their stool or is coughed up.
- If a large number of eggs have been ingested, or if the worms move from the small intestine to other parts of the body, they can cause serious complications, such as a bowel obstruction.
96
Diff dx of ascariasis
- Acute cholangitis
- Cholecystitis
- Asthma
- Intestinal obstruction
- Appendicitis
97
Diagnosis of ascariasis
- Microscopic examination of the stool
- Identification of adult worms in stool or emerging from the nose, mouth or rectum.
- Sputum analysis may reveal larvae or Charcot-Leyden crystals (collections of crystalloid composed of eosinophilic proteins).
- Eosinophilia may be marked while larvae migrate through the lungs, subsides once the adult worm resides in the intestine.
- CXR during pulmonary phase may show infiltrates.
98
Treatment of ascariasis
- Mebendazole 100mg po BID for 3 days or 500mg po once.
- Albendazole 400mg po once
- Ivermectin 150 to 200mcg/kg po once
99
Prevention of ascariasis
- Washing hands thoroughly with soap and water before handling food.
- Washing, peeling and/or cooking all raw vegetables and fruits before eating.
- Not eating uncooked or unwashed vegetables in areas where human feces is used as fertilizer.
- Not defecating outdoors.
100
What are the 2 main species of hookworms??
Ancylostoma duodenale and Necator americanus.
101
Etiology of hookworm infections in humans
- Hookworm is also an intestinal parasite of humans.
| - Hookworm infection is transmitted primarily by walking barefoot on contaminated soil.
102
Life cycle of hookworms in the soil
- Hookworm infection occurs when eggs are passed in the feces of an infected person.
- If an infected person defecates outside (near bushes, in a garden, or field) or if the feces from an infected person are used as fertilizer, eggs are deposited on soil.
- The eggs mature in soil and release larvae.
103
Life cycle of hookworms after penetrating the skin
- The larvae penetrate the skin and are carried through the blood vessels to the heart and then to the lungs.
- They ascend to the pharynx, and are swallowed.
- Adult worms live in the small intestine, where they attach to the intestinal wall with resultant blood loss by the host.
- Most adult worms are eliminated in 1 to 2 years, but the longevity may reach several years.
104
S/sx of hookworm infection
- Light infection may be asymptomatic.
- Often the first signs of cutaneous infection is an intensely pruritic, erythematous, or vesicular rash appears, usually on the feet or hands.
- A person with a heavy infection may experience abdominal pain, diarrhea, loss of appetite, weight loss, fatigue and anemia.
105
What is Loffler syndrome in hookworm infection?
Migration of large numbers of larvae through the lungs occasionally causes Loffler syndrome, with cough, wheezing, eosinophilia and sometimes hemoptysis.
106
Define cutaneous larva migrans
- Can occur when animal hookworms infect humans.
- It is caused by the larvae as they migrate through the skin.
- Causes itchy, erythematous, serpiginous skin lesions.
107
Diff dx of hookworms
- Acute anemia
- Amebiasis
- Asthma
- Contact dermatitis
- Scabies
108
Diagnosis of hookworms
- Microscopic examination of stool
- Thin-shelled oval eggs that are readily detected in fresh stool
- CBC- look for iron deficiency anemia
- Diagnosis of cutaneous larva migrans is based on clinical manifestations
- Eggs are not present in the stool
109
Treatment of hookworms
- Mebendazole 100 mg twice daily for 3 days (more effective than a single 500-mg dose)
- Albendazole in a single 400-mg as a single dose.
- Pyrantel pamoate 11 mg/kg (max dose 1 g) po once daily x 3 days.
- Treatment of anemia if needed.**
110
Prevention of hookworms
- Preventing unhygienic defecation and avoid direct skin contact with the soil (i.e. wear shoes, using barriers when seated on the ground).
- Preventing cutaneous larva migrans- avoid direct skin contact and treat cats and dogs for hookworms.
111
Which organism is known as whipworms?
Trichuris trichiura
112
Etiology of whipworms
Humans are the only known host of T trichiura and no animal reservoir is recognized.
113
Transmission of whipworms
- Spread via the fecal-oral route via ingestion of eggs of contaminated food or contact with contaminated hands.
- After ingestion the eggs hatch in the small intestine into the larval form, which penetrate the intestinal mucosa.
- Acquired the name for the distinctive resemblance of the adult worm to the handle and lash of a whip.**
114
S/sx of whipworms
* *Most infections are asymptomatic.
- Patients with fewer than 100 worms are frequently asymptomatic; however, they may present with lower abdominal discomfort, flatulence, and diarrhea or constipation.
115
S/sx of heavy whipworm infection
Patients with heavy infection have hundreds to thousands of worms and may present with lower or epigastric pain, vomiting, abdominal distension, anorexia, weight loss, anemia, diarrhea, tenesmus (painful straining), and rectal prolapse.
116
Define trichuris dysentery syndrome
Observed in heavy infections and characterized by bloody mucoid diarrhea, small frequent stools, tenesmus, anemia, and growth retardation.
117
Diff dx of whipworms
- Ascariasis
- Colitis
- Constipation
- Diarrhea
- Amebiasis
118
Diagnosis of whipworms
- Based on the microscopic detection of eggs or larvae in fresh or fixed stool samples.
- The eggs are bile stained with characteristic barrel (American football) shape with translucent polar plugs.
119
Treatment of whipworms
- Mebendazole 100 mg twice daily for 3 days (more effective than a single 500-mg dose)
- Albendazole in a single 400-mg twice daily for 3 days.
- Treatment of anemia if needed.
120
Prevention of whipworms
- Avoid ingesting soil that may be contaminated with human feces.
- Wash your hands with soap and warm water before handling food.
- Teach children the importance of washing hands to prevent infection.
- Wash, peel, or cook all raw vegetables and fruits before eating.
- Cook meat to safe temperatures.
121
Which organism causes pinworms?
enterobius vermicularis
122
Etiology of pinworms
- Enterobiasis- intestinal infestation by the pinworm E. vermicularis, usually in children.
- Humans are considered to be the only hosts of E. vermicularis and transmitted human to human.
- MC helminthic infection in the US.
- Most cases occur in school aged children, adults who care for children, or family members of an infected child.
123
Pinworm life cycle
- Eggs are deposited in the perianal folds.
- Infection results from transfer of eggs from the perianal area to fomites.
- Self infection occurs by transferring infective eggs to the mouth with hands that have scratched the perianal area.
- Some small number of eggs may become airborne and inhaled.
- These would be swallowed and follow the same development as ingested eggs.
- Following ingestion of infective eggs, the larvae hatch in the small intestine.
124
Pinworm life cycle
| -maturity
- Pinworms reach maturity in the lower GI tract within 2-6 weeks.
- The egg carrying females migrates nocturnally outside the anus to deposit eggs.
- The sticky gelatinous substance in which the eggs are deposited and the movement of the female worm causes perianal pruritus.
125
S/sx of pinworms
- Most infected people have no signs or symptoms, but some experience perianal pruritis.
- Can develop perianal excoriations and secondary infections from scratching.
- Some report abdominal pain, insomnia.
- Can obstruct the appendiceal lumen in cases of appendicitis.
126
Diagnosis of pinworms
| -first option
- The first option is examination of the perianal region for worms, ova or both.
- Usually done 2-3 hours after the infected person goes to sleep.
127
Diagnosis of pinworms
| -second option (tape method)
- The second option is to touch the perianal skin with transparent tape to collect possible pinworm eggs around the anus first thing in the morning.
- If a person is infected, the eggs on the tape will be visible under a microscope.
- The tape method should be conducted on 3 consecutive mornings right after the infected person wakes up and before he/she does any washing.
128
Diagnosis of pinworms
| -third option
- The third option is analyzing samples from under fingernails under a microscope.
- An infected person who has scratched the anal area may have picked up some pinworm eggs under the nails.
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Should you use a stool sample to diagnose pinworms?
- Since pinworm eggs and worms are often sparse in stool, examining stool samples is not recommended.
- Serologic tests are not available for diagnosing pinworm infections.
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Treatment of pinworms
- Since pinworm infestation is seldom harmful, prevalence is high and reinfestation is common.
- Mebendazole 100mg po x 1 and then single dose again in 2 weeks.
- Albendazole 400mg po x 1 and then single dose again in 2 weeks.
- Pyrantel pamoate 11mg/kg (max dose of 1 gm) po x 1 and then again in single dose in 2 weeks.
- Antipruritic creams or ointments can be applied to the perianal region to help relieve itching.
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Prevention of pinworms
- Washing your hands with soap and warm water after using the toilet, changing diapers, and before handling food .
- People who are infected should bathe every morning to help remove a large amount of the eggs on the skin.
- Infected persons should also keep their nails trimmed.
