Pediatrics notes about "Parasitic Infestation". These notes were published in 2018. You can download them also from - Telegram: https://t.me/pediatric_notes_2018 - Mediafire: http://www.mediafire.com/folder/u5u60m184t9z7/Pediatric_Notes_2018

1. Parasitic Infestation
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Infection 2018
Kareem Alnakeeb
Parasitic Infestation
Helminths (worms) - Multicellular, organized internal structure
- Includes;
• Platyhelminths (Flat worms)
• Nematodes (Round worms)
Protozoa - Single celled, Organized cellular structure
- May ingest solid particles
- Require aquatic environment
- Reproduce by binary fission at some point in life cycle
Ectoparasites Insects and Arachnida found on skin
Platyhelminths
(Flat worms)
Nematodes
(Round worms)
Protozoa
 Trematodes (Flukes);
• Fasciola (Liver flukes)
• Schistosoma (Blood flukes)
 Cestodes (Tape worms);
• Diphyllobothrium
• Taenia
• Echinococcus
 Intestinal;
• Enterobius vermicularis
• Ascaris lumbricoides
• Strongyloides stercoralis
• Hook worms
• Trichinella spiralis
• Trichuris trichiura
 Tissue;
• Toxocara canis
• Filaria:
• Amoeba
(Entamoeba histolytica)
• Flagellates:
Giardia lamblia,
Trichomonas
• Trypansoma
• Sporozoa:
Plasmodium
• Toxoplasma gondii
• Cryptosporidium
parvum
• Cyclospora
Cayetanensis
Skin Lymphatic
- Onchocerca
volvulus
- Loa loa
- Wuchereria
bancrofti
 Treated By;
- Praziquantel
- Triclabendazole
- Albendazole
- Niclosamide
 Treated By;
- Albendazole
- Mebendazole
- Ivermectin
Types of parasites:
Classifications of parasites:

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• Predominant intestinal parasites  (Intestinal entry & maturation);
E.g., Enterobius (pinworm) – Trichuris
• Intestinal entry, disease elsewhere  (Larval stage leaves the gut);
E.g., Echinococcus (Hydatid) – Trichinella (Trichinosis) – Toxoca (toxocariasis)
• Skin entry, gut manifestations  (Mature stage enters the gut);
E.g., Hook worm - Strongyloides
• Skin entry, disease elsewhere  (Dissemination);
E.g., Malaria
Trematodes (Flukes)
1. Fascioliasis
Habitat: - Hepatobiliary (bile ducts)
Infective Stage: - Encysted Metacercaria
Mode of infection: - Oral
- Fever
- Eosinophilia
- Hepatobiliary disease: biliary obstruction  biliary colic, obstructive jaundice
1. CBC → eosinophilia
2. M/E of stool concentrate
3. Serology
4. Ultrasound
- Triclabendazole (10 mg/kg once)
- Praziquantel
Human diseases caused by parasites:
Life cycle:
C/P:
Diagnosis:
Treatment:

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2. Schistosomiasis (bilharzia)
Habitat: - Intestinal / genitourinary vasculature
Infective Stage: - Cercaria
Mode of infection: - Skin penetration
 Stage of invasion: Cercarial dermatitis (swimmer’s itch)
 Acute schistosomiasis (Katayama syndrome); Katayama fever
 Stage of migration: cardiopulmonary, CNS, … etc.
 Chronic schistosomiasis:
Urinary schistosomiasis Intestinal schistosomiasis Hepato-splenic schistosomiasis
- Hematuria
- Chronic infection
- Obstructive uropathy
- Granulomas →
o Polyps
o Strictures
o Malabsorption
o Protein loss
- Pipe-stem periportal fibrosis
- Portal hypertension →
o Ascites
o Varices
o Splenomegaly
- Normal Hepatic function
1. Urine & stool analysis → for egg. (gold standard diagnostic test)
2. Rectal Snip or Bladder biopsy
3. Serology
- Praziquantel (40 mg/kg, divided bid for one day)
Life cycle:
C/P:
Diagnosis:
Treatment:

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Cestodes (Tapeworms)
1. Echinococcosis
Habitat: - Extraintestinal
Infective Stage: - Egg
Mode of infection: - Oral
(Hydatid cyst disease)
- Pressure symptoms
- Rupture of a cyst → Anaphylaxis
1. Imaging Studies:
 Ultrasonography is the most valuable tool.
2. Serology: Indirect haemagglutination (IHA) test
 Albendazole (15 mg/kg/day bid for 1-6 mo)
 PAIR procedure
 Surgery
2. Diphyllobothrium latum (fish tapeworm)
 C/P: Vitamin B12 deficiency (tapeworm competes for B12 in intestine) → megaloblastic anemia
 Treatment: Praziquantel
3. Taenia saginata (beef tapeworm)
 C/P: Asymptomatic or vague abdominal pain & distention
 Treatment: Praziquantel
Life cycle:
C/P:
Diagnosis:
Treatment:

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Intestinal Nematodes (Round worms)
1. Ascaris lumbricoides (giant roundworm)
Habitat: - Small intestine
Infective Stage: - Egg
Mode of infection: - Oral
Löffler syndrome.
GI manifestations:
- Abdominal pain & distension
Complications:
- Bowel obstruction
- Biliary obstruction → Jaundice, biliary colic
- Appendicitis
1. CBC → eosinophilia (during the pulmonary migration phase)
2. Stool Examination→ for egg
- Albendazole (400 mg PO once)
- Mebendazole (100 mg PO bid for 3 days)
- Flubendazole
- Ivermectin
- Piperazine citrate (for 3 days)
- pyrantel pamoate (11 mg/kg)
- Nitazoxanide:
► 100 mg bid for 3 days for children < 3 years
► 200 mg bid for 3 days for children > 3 years
Life cycle:
C/P:
Diagnosis:
Treatment:
Most common helminth worldwide

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2. Hookworms
(Ancylostoma duodenale, Necator americanus)
Habitat: - Small intestine
Infective Stage: - filariform larva
Mode of infection: - Skin penetration
Skin manifestations:
- Papulovesicular rash
Pulmonary manifestations:
- Löffler syndrome
GI manifestations:
- Abdominal pain & distension
- Diarrhea with blood loss
Iron-deficiency anemia due to; blood loss.
1. CBC → eosinophilia (during the pulmonary migration phase)
2. Stool Examination→ for egg
- Albendazole (400 mg PO once)
- Mebendazole (100 mg PO bid for 3 days)
- Flubendazole
- Ivermectin
- Piperazine citrate (for 3 days)
- pyrantel pamoate (11 mg/kg)
- Nitazoxanide:
► 100 mg bid for 3 days for children < 3 years
► 200 mg bid for 3 days for children > 3 years
Life cycle:
C/P:
Diagnosis:
Treatment:

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3. Strongyloides stercoralis ( threadworm)
Habitat: - Small intestine
Infective Stage: - filariform larva
Mode of infection: - Skin penetration / intestinal penetration
 Uncomplicated:
Skin manifestations:
- Cutaneous larva migrans (Creeping eruption); pruritic rash
GI manifestations:
- GI upset: anorexia, nausea, abdominal pain
- Diarrhea + malabsorption
Pulmonary manifestations: (by Migrating Larva);
- Löffler syndrome → cough and eosinophilia
 Hyperinfection syndrome (disseminated disease):
- More common in immune compromised individuals
 GI symptoms:
- Abdominal pain, vomiting, Diarrhea, Steatorrhea
- Malabsorption syndromes, protein losing enteropathy, weight loss
 pulmonary symptoms
- Cough, dyspnea, bronchospasm, pleuritic pain, pleural effusion, and hemoptysis
 Skin symptoms
- Rash (allergic due to skin penetration)
 Gram-negative bacilli sepsis
1. CBC → Profound eosinophilia (maybe absent in immunodeficiency)
2. Stool Examination→ for larva
3. Duodenal Aspiration → for Rhabditiform larva
4. CXR → infiltrates
- Ivermectin (200 μg/kg/d for 2 days)
- Thiabendazole (25 mg/kg/d for 2 days)
Life cycle:
C/P:
Diagnosis:
Treatment:

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4) Trichinella spiralis
Habitat: - Intestinal worm / Muscle cyst
Infective Stage: - Encysted larva
Mode of infection: - Ingestion of undercooked infected meat (especially pork)
- Trichinellosis is acquired by ingesting meat containing cysts (encysted larvae) of Trichinella.
- After exposure to gastric acid and pepsin, the larvae are released from the cysts and invade
the small bowel mucosa where they develop into adult worms
- The females release larvae that migrate to the striated muscles where they encyst.
(Trichinosis)
 Intestinal phase (by Adult worm);
- Abdominal pain, vomiting and diarrhea
 Invasive phase (by Migrating Larva);
- Classic symptoms of
1) Fatigue and myalgia
2) Fever + chills
3) periorbital edema
4) Eosinophilia
Pulmonary manifestations: cough, dyspnea
+ Neurological manifestations: encephalitis
+ Cardiac manifestations: myocarditis
 Convalescent phase: (by encysted Larva); most symptoms subside within a few months
 Patients with high-intensity infection may die from: (myocarditis, encephalitis, or pneumonia)
1. CBC → >10% Eosinophilia (often 50%)
2. ↑ serum creatine phosphokinase (CPK)
3. Serology 4. Muscle biopsy
- Self-limited (2% mortality)
- Albendazole / Mebendazole
Life cycle:
C/P:
Diagnosis:
Prognosis:
Treatment:

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5) Trichuris trichiura (whipworm)
(In heavy infection)
- Diarrhea with blood loss
- Anemia
- Tenesmus & rectal prolapse
- Albendazole, Mebendazole, pyrantel pamoate
6) Enterobius vermicularis (Oxyuris / pinworm)
- Perianal rash & nocturnal pruritus
1. CBC → eosinophilia (during the pulmonary migration phase)
2. Stool Examination→ for egg
- Albendazole (400 mg PO once) is the treatment of choice
- Mebendazole (100 mg PO bid for 3 days)
- Flubendazole
- Ivermectin
- Piperazine citrate (for 3 days)
- pyrantel pamoate (11 mg/kg)
- Nitazoxanide:
► 100 mg bid for 3 days for children < 3 years
► 200 mg bid for 3 days for children > 3 years
C/P:
Treatment:
C/P:
Diagnosis:
Treatment:

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Tissue Nematodes (Round worms)
1. Filaria
Lymphatic dwelling Skin dwelling
Examples:  Wuchereria bancrofti,
 Brugia malayi
 Brugia timori
 Onchocerca volvulus
 Loa loa
Habitat:
(Adult worm pairs)
- Peripheral lymphatics - Skin nodules or migratory
Intermediate host:
(Arthropod vector)
- Female mosquitoes - Female biting flies
Infective Stage: - 3rd
stage infective larvae in mouth of infected I.H
Diagnostic Stage:
(Larvae/Microfilaria)
- Circulate in bloodstream - Migrates through dermis
Mode of infection: Insect bite
a) Wuchereria bancrofti
- Elephantiasis
1. CBC → Eosinophilia
2. Blood film→ microfilaria
- Diethylcarbamazine
- Surgery
Life cycle:
C/P:
Diagnosis:
Treatment:

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b) Loa loa (African eye worm)
Calabar swelling;
1. CBC → Eosinophilia
2. Blood film→ microfilaria
- Diethylcarbamazine
C. Onchocerca volvulus
River blindness
1. CBC → Eosinophilia
2. Blood film→ microfilaria
- Ivermectin (for river blindness) → drug of choice
- Diethylcarbamazine
2. Toxocara
Habitat: - Extraintestinal
Infective Stage: - Egg
Mode of infection: - oral
(Toxocariasis)
 Visceral larva migrans (VLM)
 Ocular larva migrans (OLM)
 Covert toxocariasis
- Albendazole; self-limiting in most cases
C/P:
Diagnosis:
Treatment:
C/P:
Diagnosis:
Treatment:
Life cycle:
C/P:
Treatment:

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Protozoa
1. Entamoeba histolytica
 C/P: (Amebiasis)
- Abdominal pain & distension,
- bloody diarrhea (dysentery),
- Anemia (blood loss),
- Intestinal perforation (Transmural necrosis).
2. Giardia lamblia
 C/P: (Giardiasis)
- Abdominal pain & distension,
- diarrhea + malabsorption
- Anemia.
3. Cryptosporidium
 C/P:
- Abdominal pain & distension
- diarrhea + malabsorption
Home message
- Human diseases caused by parasites may have intestinal, skin, pulmonary or systemic
manifestations
- Intestinal parasites are usually diagnosed by stool analysis.
- Invasive parasites are usually diagnosed by eosinophilia, serology, radiology and biopsy.
- Platyhelminths (Flat worms) are treated by Praziquantel, Triclabendazole, Albendazole &
Niclosamide.
- Nematodes (Round worms) are treated by Albendazole, Mebendazole & Ivermectin.

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Parasite Human
Habitat
Infective
stage
Mode of
infection
C/P Diagnosis Treatment
1. Platyhelminths (Flat worms)
Schistosoma Intestinal /
genitourinary
vasculature
Cercaria Skin
penetration
• Katayama
fever
• Hepatosplenic
• Other organs
• Urine & stool
analysis for
eggs
• Rectal snip or
bladder biopsy
• Serology ??
-Praziquantel
Fasciola Hepatobiliary Encysted
metacercaria
Oral • Hepatobiliary
disease
• Fever,
eosinophilia
• M/E of stool
concentrate
• Eosinophilia
• Serology
• Ultrasound
-Praziquantel
-Triclabendazole
Echinococcus Extraintestinal Egg Oral • Pressure
symptoms
• Anaphylaxis
• Radiology
• IHA
-Albendazole
-PAIR procedure
-Surgery
2. Nematodes (Round worms)
Ascaris Small intestine Egg Oral • Abdominal
pain, Bowel
obstruction
• Loffler-like
• Stool M/E for
eggs
• Eosinophilia in
pulmonary
- Albendazole
- Mebendazole
- Flubendazole
- Ivermectin
- pyrantel
pamoate
- Piperazine
citrate
- Nitazoxanide
Hookworms Small intestine Filariform
larva
Skin
penetration
• Cutaneous
• Intestinal
• Iron
deficiency
anemia
• Loffler-like
Strongyloides Small intestine Filariform
larva
Skin,
intestinal
penetration
• Cutaneous
• Intestinal
• protein
losing
enteropathy,
sepsis
• Loffler-like
• Larva in stool,
duodenum
• Eosinophilia
- Ivermectin
- Thiabendazole
Trichinella • Intestinal
worm
• Muscle cyst
Encysted
larva
Ingestion of
raw meat
• Intestinal
• Muscle,
systemic
• Eosinophilia
Toxocara Extraintestinal Egg Oral • VLM
• OLM
• Covert
toxocara

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Filaria • Lymphatic
• Skin
Larva Insect bite • Elephantiasis
• River
blindness
• Calabar
swelling
• Blood film for
microfilaria
• Eosinophilia
- Diethylcarba
mazine
- Ivermectin
(for
Onchocerca)
Symptom Mechanism Parasite
Abdominal pain & distension Ascaris, Hookworm
Taenia
Amoebiasis,
Giardia, Cryptosporidium
Diarrhea + Malabsorption Strongyloides
Giardia, Cryptosporidium
Diarrhea with blood loss Hookworm, Trichuris
Amoebiasis
Intestinal parasites
Anemia Blood loss S.mansoni
Hookworm, Trichuris
Amoebiasis
Malabsorption Diphyllobothrium
Giardia
Malnutrition Heavy infestations
Skin Rash Papulovesicular Hookworm
Creeping eruption Strongyloides
Perianal rash & pruritus Entrobius
Respiratory Symptoms Pulmonary migration Ascaris
Hookworm
Strongyloides
Toxocara
Intestinal obstruction Worm bolus Ascaris
Appendicitis Obstruction Ascaris
Jaundice, biliary colic Biliary obstruction Ascaris
Fascioliasis
Prolapsed rectum Tenesmus, weight loss Trichuris
Intestinal perforation Transmural necrosis Amoebiasis