Parasitology Flashcards
What is parasitology?
Study of organisms which parasitize other organisms
What is a parasite?
An organism which lives of other organisms called hosts in which the host does not benefit.
What is Parasitology the study of?
The interaction between parasites and hosts.
Parasites of human and other animals.
Genesis and development of parasitoses in the host.
Taxonomy, morphology, life cycles, and living needs of
parasites in the environment and in its host.
Diagnosis, treatment, and prevention of parasitoses.
Purpose of studying parasitology?
To protect man and animals from parasitic infections.
To improve the health status of man and animals
What are zoonoses?
Animal Parasites transmitted to humans
Describe the life cycle of a parasite?
- eggs in feces passed into environment
2.eggs ingested
3.oncospheres hatch, penetrate intestinal wall and circulate to musculature - a.human infected by ingesting raw, undercooked animal’s meat
4.b oncospheres develop into cysticerci in muscles
Cysticerci can develop in any organ being more common in subcutaneous tissues as well as brain and eyes - scolex attaches to intestine= adults in small intestine
What is the infective Stage?
Is a stage when a parasite can invade animal body and live in it .
What is Definitive (Final) Host?
The host that harbors the adult or sexually mature stages of the parasites. E.g. Humans for the beef tapeworm.
What is Intermediate Host?
The host that harbors the immature or larval stages of the parasites. There is further development to become infective to the final host. E.g. cattle for the beef tapeworm.
What is Transport Host?
Similar to the intermediate host but the parasites does not undergo further development in this host. E.g. Earthworms for some nematode eggs
What is Paratenic Host?
The final host is infected by ingesting the paratenic host which harbors the parasites. A paratenic host is also a waiting host
E.g. the successive fish hosts that are needed to
carry the broad fish tapeworm
What is Reservoir Host?
A host (susceptible host) that maintains the larval and sometimes the infective stages of parasites and may pass infection to other species e.g most animals
What are the three branches of Parasitology?
Protozoology
Helminthology
Entomology
What are the phylum found under the branch protozoology?
Phylum Sarcomastigophora
Phylum Apicomplexa
Phylum Ciliophora
Phylum Microspora
What are the two subphyla of sacromastigosphora?
- Subphylum Sarcodina
2. Subphylum Mastigophora
Example of Parasite found under subphylum Sarcodina and its structure.
Entamoeba histolytica
pseudopodia the way they move- form of locomotion, nucleus, contractile vacuole
Example of Parasites found under subphylum Mastigophora.
- Giardia duodenalis
- Trichomonas spp.
- Leishmania spp.
Describe structure of gardia duodenalis.
How is it transmitted?
Flagellum- aid in locomotion
cyst form- encapsulated- based on environment
Trophozoite- mobile
Fecal matter
How is trichomonas spp transmitted?
Reproductive tract
sexually transmitted
How is Leishmania spp transmitted?
Blood
Describe life cycle of giardia duodenalis.
& characteristics of its infection.
Causes giardiasis
Cyst (passed into environment) -> trophozoites (exist in human intestine)
Diarrhoea, gas/bloating, greasy stools, stomach/abdominal cramps, dehydration.
Example of Parasites found under phylum Apicomplexa.
How are they transmitted?
- Plasmodium spp.- blood
- Toxoplasma gondii- blood
- Cryptosporidium spp.- fecal matter
Examples of Parasitie found under Phylum Ciliophora?
Blantidium coli
Describe life cycle of blantidium coli
& characteristics of its infection.
Causes blantidiasis large parasite swines are reservoirs Mostly asymptomatic Persistent diarrhoea Abdominal pain Perforated colon transmitted in fecal matter
What are the phylum found under the branch helminthology?
- Platyhelminthes
2. Nemathelminthes
What type of worms are Platyhelminthes?
Example?
Flat worms
e.g. flukes, tapeworms
What type of worms are Nemathelminths?
Round worms
What are the two classes in which the phylum Platyhelminthes is divided into?
- Cestoda (tapeworms)
2. Trematoda (flukes)
Describe Cestoda.
Shape
Sexes
‘Head’ End
Tape-like; segmented
sexes not separate, monoecious
suckers present often with hooks
Describe Trematoda. Shape Sexes 'Head' End Alimentary Canal
leaf-like; unsegmented
sexes not separate; monoecious except schistosomes
suckers present no hooks
alimentary canal present but incomplete; no anus
Describe Nematoda. Shape Sexes 'Head' End Alimentary Canal Body cavity
elongated, cylindrical, unsegmented
separate, diecious
no suckers, no hooks, well developed buccal capsule in some
alimentary canal present and complete, anus present
body cavity present
Examples of worms in class Cestoda?
- Taenia spp- beef tape worm
- Echinococcus spp.- dog tapeworm
- Taenia solium- pork tape worm
Describe the characteristics of taenia solium infection.
disease: taeniasis
pork tapeworm
Larvae can encyst in brain and other tissue
Adult onset of seizures in low-income countries
Examples of worms in class Trematoda?
- Clonorchis sinesis
2. Schistosoma spp.
Examples of worms in class Nematoda?
- Ascaris lumbricoides
- Trichuris trichiura
- Ancylostoma spp.
Describe the characteristics of ascaris lumbricoides infection.
Causes ascariasis Soil-transmitted helminth- infected feces Associated with poor hygiene & sanitation Usually asymptomatic Abdominal discomfort Intestinal blockage Impaired growth in children Coughing
Describe the characteristics of trichuris trichiura infection.
Usually asymptomatic
Gastrointestinal problems
Abdominal pain, diarrhoea, rectal prolapse
Growth retardation
Describe the characteristics of ancylostoma spp infection.
Soil-transmitted nematode
Causes Cutaneous Larval Migrans (CLM) in humans
Severe itching of infected skin
Ancylostoma duodenale and Necator americanus
found in GIT of humans
What are the insects found in the class insecta?
Louse Fly Mosquito Bed bug Flea
What are the two divisions of the class Arachnida?
- Mites
2. Ticks
What are the two types of mites and the diseases they cause?
- Sarcoptes scabei- scapies(human), mange(dog)
2. Demodex spp
What are the two types of ticks and the disease they cause?
- Black legged deer ticks- Lyme Disease
2. Brown Dog ticks- canine babesiosis
What is Pathogenicity?
The ability of an organism to produce or cause disease (i.e. harm the host).
What is virulence?
Refers to the degree of pathology caused by the
organism.
What does pathogenicity of a parasite depend on?
Type of parasites
Number of parasites present in the host (parasite burden)
Whether migration takes place or not in the host
Degree of adaptation that has developed between the host and parasite
In what ways do parasites harm their hosts?
10
- By absorbing (sharing) readily digested food materials intended for the host. e.g. Tape worms, ascaris
- By feeding on the tissues of the host. Feed on plugs of solid tissue. E.g. Ascaris.
- By causing mechanical obstruction or pressure. Obstruct hollow organs like intestine.
- By causing wounds through which infection may enter into the body. Eg. Hookworms
- By causing growth of tumors E.g. pork tapeworms
- By causing irritation to the host. E.g. Lice, ticks, pinworms.
- By transmitting the causative agents of infectious diseases (serving as vectors).
- By causing cell destruction especially protozoan parasites. E.g. Plasmodium spp.
- By secreting toxins or other harmful substances such as: Anti digestive enzymes: E.g. GIT worms
- By reducing immune status of their hosts
How do Parasites enter the body?
5 routes
- Entry through the natural openings: Mouth, anus,
and openings of the respiratory tract. - Entry through the skin:
E.g. Hookworms - Entry through blood sucking arthropods:
E.g. Malaria (Plasmodium spp.) - Transplacental transmission:
E.g. Toxoplasma gondii - Transmammary (colostrum or milk) route: E.g. Hookworms
How are Parasitic Infections Diagnosed?
1.Clinical diagnosis
2. Laboratory diagnosis:
Faecal Exam: Direct smear
Faecal Flotation
Faecal sedimentation
Urine exam: centrifugation method
Blood exam: Blood smears and staining
How are Parasitic Infections treated?
- Chemotherapy
(e. g. Anthelmintics) - Surgical
- Adequate nutrition
What are prevention and control methods to reduce Parasitic Infections?
1.Reduction in sources (proper hygiene, sanitation) 2. Public education 3. Destruction and/or control of reservoir hosts and vector 4. Vaccines
