Helminthes Diseases

• Nematodes - roundworms
• Platyhelminthes - flatworms
• Trematodes - flukes
• Cestodes - tapeworms
• Trematodes - flat, leaf-shaped and unsegmented. They are hermaphroditic, meaning they have the reproductive organs associated with both males and females
• Nematodes - are cylindrical and have lips, teeth , and dentary plates. The worms are either male or female.​
• Cestodes - is segmented and hermaphroditic. They have a sucker and a projecting, hooked rostellum
• “cycle of carnivorism” - among hogs and rats​


  Trichinellaspiralis- life cycle​
• Trichinella spiralis :

  • humans ingest encysted larvae in infected, undercooked pork​
  • larvae exist in stomach and burrow into small intestinal mucosa​
  • adult males and female reemerge and produce larvae which penetrate intestine and circulate in bloodstream​
  • larvae enter skeletal muscle cells and encyst​
•  Trichinosis signs and symptoms:

  • muscle pain and tenderness ​
  • fever +/- chills​
  • Abdominal pain​
  • edema (often periorbital)
• Diagnosis for Trichinosis:

  1. Blood Test
  2. Muscle Biopsy
• Treatment of Trichinosis:

  • Antihelminthic
  • Steroids
  • Antipyretics
• Antihelminthic (albendazole) - to kill any intestinal worms and larvae
• Steroids - relieve inflammatory reactions during larva migration
• Antipyretics - to relief muscle pain
• Trichinella spiralis

  • Onchocerca volvulus microfilaria
  • Onchocerca volvulus nodule
  • Dirofilaria
• Schistosomiasis S&S: Urinary Schistosomiasis​

  • S. hamatobium​
  • Gross haematuria​
  • Dysuria​
  • Bladder, ureters and kidneys damaged Cancer of the bladder is common​
• Schistosomiasis ​- a parasitic disease caused by the parasite Schistosoma
• Diagnosis of Schistosomiasis: Microscopy of Eggs

  • urine sediment for S. haematobium ​
  • concentrated stool samples for S. mansoni, S. japonicum​
  • Serology – all species​
  • Rectal biopsy - S. mansoni, S. japonicum​
• Schistosomiasis S&S: Intestinal schistosomiasis

  • S. mansoni, S. japonicum​
  • Gradual enlargement of liver and spleen intestines ​
  • hypertension of the abdominal blood vessels which begin to bleed​
  • Blood in the stools​
• Schistosomiasis Treatment:

  • Praziquantel: effective against all species​
  • S. haematobium: single dose (40 mg/kg) ​
  • S. mansoni, S. japonicum: 2-3 doses of 30mg/kg​
• Haematuria - due to S. haematobium
• Epidemiology​: Schistosomiasis

  • 200m people in 74 countries infected, 85% of whom live in sub-Saharan Africa​
  • S. haematobium - Africa and middle east (most prevalent)​
  • S. Mansoni - Africa and Latin America​
  • S. japonicum – Pacific region​
• • Shistosoma eggs become trapped in the tissues of the urinary tract (S. haematobium) and intestines (S. mansoni, S. japonicum)​This results in inflammatory response and tissue damage​
• Schistosomiasis clinical features:

  • ​Cercarial dermatitis - skin rash "swimmer's itch"
• Schistosomiasis clinical features:

  • Intestinal schistosomiasis (granulomas --> polyps, protein loss, malabsorption, strictures)​
• Schistosomiasis clinical features:

  • Hepatosplenic schistosomiasis (portal hypertension --> ascites, varices, splenomegaly, normal hepatic function)​
• Schistosomiasis clinical features:

  • Urinary schistosomiasis (hematuria, chronic infection, obstruction)​
• Drug treatment of schistosomiasis:

  • Praziquantel increases permeability of adult parasite ​
  • Tetanospasm --> death​
• Control of Schistosomiasis​:

  • REDUCE CARRIERS = mass rx program​
  • ELIMINATE SNAILS =molluscicides​

                                    destroy snail habitats​

                                             snail-eating fish​

  • PREVENT WATER ​CONTAMINATION = latrines, toilet , public health education​

  PREVENT HUMAN ​EXPOSURE = water systems​
• Definitive hosts: harbor adult worms​
• Intermediate hosts: harbor tissue cysts (containing worm heads)​
• Humans acquire infection in two ways:​

  • ingestion of eggs from feces (to acquire tissue cysts)—definitive host​
  • ingestion of tissue cysts in undercooked meat (to acquire a tapeworm)- Intermediate host​
• Taeniasis - is an infection caused by the tapeworm
• Cysticercosis - pork tapeworm
• Tapeworm:

  • Ingestion of undercooked pork
  • poor sanitation
  • poor hygiene
• Intestinal Taeniasis​:

  Pathogen:

  •  Taenia solium (pork tapeworm) ​
  • Taenia saginata (beef tapeworm) ​
  • Mode of transmission: Ingestion of larvae (cysticerci) in raw or undercooked beef/pork
• Cysticercosis:

  Pathogen:

  •  Taenia solium (pork tapeworm)​
  • MOT: Fecal-oral ingestion of eggs from feces of humans with intestinal taeniasis ​
  • Cysticercosis can cause cysts in the brain and seizures​
• Epidemiology of  Cysticercosis​:

  • Approximately 50 million people worldwide are estimated to have cysticercosis infection​
  • Endemic in many regions of Central and South America, sub-Saharan Africa, India, and Asia
• Echinococcosis: Cystic Hydatid Disease​

  • ingestion of eggs in pasture (cattle?)
  • ingestion of entrails (dog)
  • contact with dogs (human)