Can be acquired from ingestion of raw or poorly cooked pork
Echinococcus granulosis
Adult tapeworm found in intestine of dogs, hydatid cysts found in sheep or humans
Taenia solium
Humans can serve as definitive and/or intermediate host
Ascaris lumbricoides eggs require a period of development in the soil before they are infective for humans
Echinococcus granulosus
Causes cystic hydatid disease, humans are accidental intermediate host
Enterobius vermicularis, the pinworm, may be the most common parasitic infection throughout the world
Trematodes
Have a freshwater snail in the life cycle
Urinary Schistosomiasis
Transmitted by Bulinus species of mollusk
Control of Schistosomiasis
Treating water sources with molluscicides reduces mollusc nesting, helping stop the spread of infection
Worm infections
Human diseases caused by platyhelminthes (flatworms) or nematodes (roundworms)
Most important human worm infections
Schistosomiasis
Taeniasis
Cysticercosis
Ascariasis
Ancylostomiasis (hookworm infection)
Ecological control methods for bilharzia
Stocking ducks and fish which eat the snails
Enterobius vermicularis
Helminthic parasite whose mode of transmission is by air, causes enterobiasis
Reason for higher prevalence of helminth infections in developing countries
Lack of plumbing systems leads to exposure to human feces
Schistosomiasis
Worm infection caused by schistosomes, a species of flatworms
Schistosomes
Dioecious, have separated sexes (male and female individuals)
Types of trematoda (flukes)
Urinary bilharzias (Schistosoma haematobium)
Intestinal bilharzias (Schistosoma mansoni)
Bilharzia infection
Also known as Swimmers itch
Intestinal bilharzias (Schistosoma mansoni)
Presents with blood and mucus in the stool of an infected person
Differentiation between urinary and intestinal bilharzias
Urinary bilharzias have terminal spine, intestinal bilharzia has lateral spine
Intermediate host of Schistosoma mansoni
Gastropod mollusc (snail) living in freshwater
Progression of schistosomiasis disease
Cercarial rash, bronchial cough, lassitude, frequent urination, blood and mucus in stool, abdominal pain, splenic and liver enlargement, bladder scarring, malignant tumors, heart failure, blindness, CNS complications, death
Ascaris lumbricoides
Common roundworm
Symptoms of Ascaris lumbricoides infection
Vague abdominal discomfort
Acute pains
Vomiting
Diarrhea
Intestinal obstruction, death in heavy infestations
Control measures for Ascaris lumbricoides
Sanitary disposal of faeces
Safe water supply
Thorough washing of raw foods
Education on hand washing and not eating dropped food
Control measures for Enterobius vermicularis (pinworm)
Sanitary disposal of human excrement
Hand washing after toilet and before food preparation
Nail cleaning and care
Reduction in overcrowding
Laundry in hot water
Early detection and treatment
Discouraging eating of sand
Hookworms
Have mouthparts with hooks or "teeth" to facilitate fixation in intestine and blood feeding
Taenias
Platyhelminth animals (flatworms), cause taeniasis and cysticercosis
Main species of taenias causing human disease
Taenia solium (pork tapeworm)
Taenia saginata (beef tapeworm)
Difference between Taenia solium and Taenia saginata
Taenia solium has pigs as intermediate host, Taenia saginata has cattle
Taenia solium
Humans are primary host, pigs are secondary/intermediate host
Life cycle of Taenia solium
Tapeworm cyst in pig muscle eaten by man, cyst evaginates and attaches to intestine, self-fertilization, ripe segments detached and passed in feces, pig eats feces containing segments, larval forms released and migrate to pig muscles, man eats uninspected pork and becomes infected
Taenia ovis
Intermediate host is sheep, definitive host is dog
Hydatid cysts
Definitive host is dog, commonly affect liver, lungs, kidney, heart, bone, CNS, thyroid in humans
Control measures for hydatid cysts
Limit dog numbers and contact with pastureland
Regular deworming of dogs
Meat inspection
Thorough cooking of viscera before feeding to dogs
Health education
Cysticercus ovis = Taenia ovis tapeworm in dogs, Cysticercus cellulosae = Taenia solium tapeworm in humans, Cysticercus bovis = Taenia saginata tapeworm in humans