Parasitology-3 Flashcards
What symptoms does Enterobius vermicularis cause?
Anal pruritus, which is worse at night.
How is Enterobius vermicularis diagnosed?
Using the tape test to visualize eggs.
What are the treatments for Enterobius vermicularis?
Bendazoles or pyrantel pamoate
What are the main clinical effects of Ascaris lumbricoides infection?
Intestinal obstruction at the ileocecal valve
Biliary obstruction, intestinal perforation
Migration to the lungs causing Löeffler syndrome (pulmonary eosinophilia)
What is the treatment for Ascaris lumbricoides?
Albendazole
What symptoms does Strongyloides stercoralis cause?
GI symptoms (duodenitis)
Pulmonary symptoms (dry cough, hemoptysis)
Cutaneous symptoms (pruritus)
Can cause hyperinfection syndrome in immunocompromised patients
How is Strongyloides stercoralis transmitted?
Larvae in soil penetrate the skin; rhabditiform larvae seen in feces under a microscope.
What is the treatment for Strongyloides stercoralis?
Ivermectin or Albendazoles.
What symptoms do Ancylostoma spp. and Necator americanus cause?
Microcytic anemia due to blood loss from intestinal wall attachment
Cutaneous larva migrans (serpiginous, pruritic rash)
How are hookworms transmitted?
Larvae penetrate the skin from walking barefoot on contaminated soil or beaches.
What are the treatments for hookworm infections?
Bendazoles or pyrantel pamoate.
What disease does Trichinella spiralis cause?
Trichinosis, which includes:
Fever, vomiting, nausea
Periorbital edema
Myalgia (larvae encyst in striated muscle)
How is Trichinella spiralis transmitted?
Ingestion of undercooked pork (most common) or fecal-oral (less likely).
What is the treatment for Trichinella spiralis?
Bendazoles.
How is Trichuris trichiura transmitted?
Fecal-oral route.
What is the treatment for Trichuris trichiura?
Albendazole
What disease does Toxocara canis cause?
Visceral larva migrans, which can cause:
Inflammation in the liver, eyes (visual impairment), CNS (seizures, coma), and heart (myocarditis)
Many patients remain asymptomatic
How is Toxocara canis transmitted?
Feco oral route
What is the treatment for Toxocara canis?
Albendazoles
What disease does Onchocerca volvulus cause?
River blindness (black skin nodules, “black sight”).
How is Onchocerca volvulus transmitted?
Female black fly bite.
What is the treatment for Onchocerca volvulus?
Ivermectin (for ‘river blindness’)
What disease does Clonorchis sinensis cause?
Biliary tract inflammation → pigmented gallstones; associated with cholangiocarcinoma.
How is Clonorchis sinensis transmitted?
Ingestion of metacercariae (larvae) in undercooked or raw freshwater fish.
What is the treatment for Clonorchis sinensis?
Praziquantel.
What is the common name for Clonorchis sinensis?
Chinese Liver fluke
What is the life cycle of Clonorchis sinensis?
Eggs (from infected human feces) enter freshwater.
Eggs are ingested by snails (first intermediate host) and develop into larvae.
Larvae are released into water and infect freshwater fish (second intermediate host).
Humans ingest infected fish → larvae mature in biliary ducts.
How is Clonorchis sinensis diagnosed?
Detection of operculated eggs in stool (stool microscopy).
What diseases does Schistosoma cause?
Schistosoma mansoni & japonicum: Liver/spleen enlargement, fibrosis, inflammation, portal hypertension
Schistosoma haematobium: Squamous cell carcinoma of the bladder (painless hematuria), pulmonary hypertension
How is Schistosoma treated?
Praziquantel
What type of parasite is Schistosoma?
A trematode (fluke) that infects blood vessels.
What are the three major Schistosoma species affecting humans?
Schistosoma mansoni (intestinal & hepatosplenic schistosomiasis)
Schistosoma japonicum (intestinal & hepatosplenic schistosomiasis)
Schistosoma haematobium (urinary schistosomiasis)
What is the intermediate host for Schistosoma?
Freshwater snails (release infectious cercariae).
How is Schistosoma transmitted?
Direct skin penetration by cercariae in contaminated freshwater.
What disease does Schistosoma mansoni & japonicum cause?
Intestinal & hepatosplenic schistosomiasis →
Chronic diarrhea & abdominal pain
Liver fibrosis, hepatosplenomegaly, portal hypertension
Esophageal varices → Risk of variceal bleeding
What are the characteristic egg features?
S. mansoni: Large lateral spine
S. japonicum: Small lateral spine
How does Schistosoma cause portal hypertension?
Eggs get trapped in periportal veins, triggering granuloma formation and fibrosis.
What disease does Schistosoma haematobium cause?
Urinary schistosomiasis, presenting as:
Painless hematuria
Dysuria & bladder wall inflammation
Fibrosis & calcification of the bladder → Hydronephrosis
Increased risk of squamous cell carcinoma of the bladder
What is the characteristic feature of S. haematobium eggs?
Terminal spine on eggs (seen in urine microscopy).
How is Schistosoma diagnosed?
Stool (S. mansoni, S. japonicum) or urine (S. haematobium) microscopy → Detects eggs
Serology (ELISA, PCR) for chronic cases
Ultrasound, CT, MRI for liver fibrosis or urinary tract damage
What is the treatment for Schistosomiasis?
Praziquantel (drug of choice for all species).
What is the major difference between Schistosoma and other trematodes?
Unlike most trematodes, Schistosoma is dioecious (has separate male & female worms).
What is the life cycle of Schistosoma?
Eggs are excreted in urine (S. haematobium) or feces (S. mansoni & S. japonicum).
Eggs hatch into miracidia in freshwater and infect snails.
Inside snails, miracidia develop into cercariae, which are released into water.
Cercariae penetrate human skin and enter the bloodstream.
They migrate to their target veins and mature into adult worms.
What is the main site of infection for S. mansoni?
Mesenteric veins of the intestines & liver.
How is S. japonicum different from S. mansoni?
More severe liver disease (due to high egg burden).
Eggs are round with a small lateral spine.
Higher chance of brain involvement → seizures, encephalopathy.
What is the main site of infection for S. haematobium?
Venous plexus of the bladder.
What type of hypersensitivity reaction is seen in schistosomiasis?
Type IV (delayed-type hypersensitivity) due to chronic granuloma formation.
What is “Katayama fever”?
Acute schistosomiasis (hypersensitivity reaction to eggs 3-8 weeks post-infection), causing:
Fever, cough, rash, eosinophilia, hepatosplenomegaly.
Seen in travelers returning from endemic areas.
What is the gold standard for diagnosing Schistosoma infection?
Microscopy of stool or urine for eggs.
