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Clinical Parasitology Images: Gallery VI (Click on images for an enlarged view)
Metastrongyle larva (lungworms)
All metastrongyles except Metastrongylus apri pass from the definitive host as first stage larvae. When the definitive host is known, most of these larvae can be identified to species by tail modifications such as can be seen above. The modifications may be appendages, hooks, kinks, spikes, contrictions, etc. The larvae are usually found by baermannization of feces or examination of sputum or tracheal washes. Most metastrongyles are transmitted by ingestion of snails (intermediate hosts) that contain the infective larval stages. An exception is Filaroides hirthi in dogs that can be transmitted in the saliva of the mother to the pups.
Related images:
- Lungworm larva with tail appendage
- Lung with grossly visible lesions
- Filarioides osleri (Oslerus osleri) cysts in trachea and bronchi of dog
- Filarioides osleri (Oslerus osleri) cysts in trachea and bronchi of dog
Dirofilaria immitis microfilariae in blood
Dirofilaria immitis is a filarial worm transmitted by mosquitos to dogs. Microfilariae do not exhibit the normal internal anatomy of a larval nematode. There are primordial cells but the body is primarily a syncitium of nuclei which are discernable in with stains. Intestinal hemorrhage of other etiology will sometimes result in the microfilariae being found in feces.
Related image:
Dipetalonema reconditum microfilaria
These filarial worms are transmitted by fleas and biting lice. The adult worms live beneath the skin and microfilariae make their way into the main circulation where the are ingested by fleas. The main significance is that the organisms must be differentiate from heartworm
Dioctophyma renale egg (normally found in urine)
This is the egg of the giant kidney worm of dogs. The worms are transmitted in aquatic annelids and may be eaten by crayfish resulting in the latter serving as a paratenic host. Worms are usually found in the peritoneal cavity or in large cysts that destroy the integrity of the affected kidney. Eggs can only leave the body by development of a fissure to the ureter allowing eggs to pass with the urine.
Related images:
- Egg viewed by phase contrast
- More eggs
- Adult worm showing enormous size
- Drawing showing characterics of a male's fleshy bursa
Otobius megnini (soft tick called the "ear tick")
The spinose ear tick is found on horses, dog , cattle and occassionally humans. It is a soft tick and is parasitic in the nymphal stage. It is recognized by the mamillary appearance of the tegument and the large spines that cover the entire body.
Related image:
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Ear mite of dogs and cats.
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Reportable mange mite of cattle and sheep.
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Follicular mite that is the cause of demodectic mange in dogs and cats.
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This end view of a fly maggot shows a example of the spiracle morphology used to identify fly larvae to genus.
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Kissing
bug (Triatoma spp)
Also known as a "cone-nosed" bug and is one of the intermediate hosts for Trypanosoma cruzi
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Tapeworm showing scolex and representative portions of the strobila. Tapeworms with this type of egg are transmitted by ingestion of mammalian intemediate hosts that may exhibit various metacestode forms. These worms are fairly easy to eliminate and suggested control measure should reflect the mode of transmission.
Related images:
- Hooks typical of taeniid species
- Scolex and neck of a taeniid tapeworm
- Gross tapeworm showing proglottids from selected areas of the strobila
- Stained taeniid proglottids showing reproductive structures
- Adult tapeworms in small intestines
- Cysticercoid larval stage (metacestode)
- Pork measles (cysticerci in muscle of pig)
- Cysticerci in peritoneal cavity of rodent
- Adult Echinococcus granulosus
- E. granulosus hydatid cyst in brain
- Tissue section of an hydatid cyst
Mature tapeworm proglottids showing paired reproductive organs. This parasite can be distinguised in feces by the shape of the mature proglottids that are elongate with a cucumber seed shape. Taeniids are square or retangular with one prominent lateral genital pore. These parasites are more difficult to treat and control recommendations with differ greatly from those of taeniids.