Transcript Parasitology

Parasitology
Review
• Organisms that live within another
organism = endoparasite/internal
parasite – called infection
• Organisms that live upon another
organism = ectoparasite/external
parasite – called infestation
3 purposes of Parasitology
• 1. Locate
• 2. Identify/classify
• 3. Treat
Naming of Parasites
• Taxonomy – grouping of organisms
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Kingdom – animala (multicellular animals)
Phylum - Platyhelminthes (e.g. flatworms)
Class – Cestoda (e.g. tapeworms)
Order – cyclophllidea (e.g. “true tapeworms”)
Family - dipytidiidae
Genus - Dipylidium
Species - caninum
Ways in which they are named
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1. Geographic Location
2. After the person who located it
3. after the parasites morphology
4. after the animal in which it was
found
Hosts
• A host is the animal that the parasite
make their home within/on
• Host specific singular – toxacara
canis or cati
• Host specific plural – toxascaris
leoninum
3 types of hosts
• Definite: Host in which the adult
parasite lives.
• Intermediate: acts as a host to the
parasite to harbor the parasite for a
short period of time.
• Paratenic: similar to intermediate
host, but not needed for the
parasite’s development cycle to
progress.
3 types of host/parasite relationships
• Mutualism: both the host and the
parasite derive from benefits of one
another
• Commensalism: where one organism
benefits and the other is not
significantly harmed or helped.
• Parasitism: one member benefits
while the other is harmed.
Harm by parasites
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Absorb food intended for host
Sucking blood or lymph fluid
Feeding on tissues of the host
Cause mechanical obstruction or
pressure
• Cause growth of nodules or tumors
and perforate tissues or vessels
• Cause wounds through which
infection can occur
• Destruction of tissue
• Irritation
• Transmit some infectious disease
such as malaria, viruses, protozoa
• Secreting toxins or otherwise
harmful substances
Life Cycle
• Different stages that a parasite must
go through to continue to
live/reproduce
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Direct
Indirect
Pre-patent period
Host specific
Common Endoparasites
• Platyhelminthes
• Class: trematoda “flukes”
“Trematodes”; flat and leaf shaped
• Origin: Digenia – flukes of warm
blooded animal. All have and indirect
lifecycle
Family: Fascioliidea
•Genus: Fasciola
•Species: hepatica
•Common Name =
“liver fluke”
-Largest of all fluke eggs
-Makes home in the liver
-Host specific – Cattle
-Can accidentally affect humans
-The eggs are ellipsoidal. They have a small, barely
distinct operculum (upper end of the eggs). The
operculum can be opened, for example when a slight
pressure is applied to the coverslip. The eggs have a
thin shell which is slightly thicker at the abopercular
end. They are passed unembryonated.
www.dpd.cdc.gov/dpdx
Family: Troglotrematiidae
•Genus: Paragonimus
•Species: kellicoti
•Common Name = “lung
fluke”
-Host Specific – Dogs, Cats, Pigs, Humans
-2 Intermediate hosts – snail and cray fish
-Large yellowish-brown operculated eggs that
are found in the feces (or demonstrated in the
sputum). They measure 75-118 u X 42-67 u and
have a marked "shoulder" or "ridge" surrounding
the operculum.
http://cal.vet.upenn.edu/paralab/labs
Generalities of flukes
• All flukes as a whole go through 5
larval stages
• Has the snail as an intermediate host
• Lay single operculated eggs
Family : same as previous slide
•Genus: Nanophyetus
•Species salmincola
•Common condition:
“salmon poisoning”
-This species is known to infect over 30
different species of fish eating mammals,
including canids, felids, bear, and humans
–The fluke itself does not cause problems.
The fluke is a carrier of rickettsial organism
that is in salmon
-Produces disease similar to distemper
-2 intermediate hosts; snail and salmon.
Salmon ingest snail, dog ingests salmon
www.k-state.edu/parasitology
Phylum: Platyhelminths
• Class: Cestoda “tapeworms”
• Anatomy of a tapeworm
• An adult tapeworm consists of a knoblike head, or
scolex, equipped with hooks for attaching to the intestinal
wall of the host (which may be a human), a neck region,
and a series of flat, rectangular body segments, or
proglottids, generated by the neck. The chain of
proglottids may reach a length of 15 or 20 ft (4.6–6.1 m).
Terminal proglottids break off and are excreted in the
feces of the host, but new ones are constantly formed at
the anterior end of the worm. As long as the scolex and
neck are intact the worm is alive and capable of growth.
A rudimentary nervous system and excretory system run
the length of the worm, through the proglottids. However,
there is no digestive tract; the worm absorbs the host's
digested food through its cuticle, or outer covering.
Order: 2 orders of tapeworms
• 1. Pseudophillidea “false tapeworm”
• 2. Cyclophillidea “true” tapeworm”
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Do not produce larva, produce cysts
Genital pores are located on the side
1 larval stage
Produce egg baskets that contain
hexacanth embryos
Family: Dipytidiidae
•Genus: Dipylidium
•Species: caninum
•Common name:
“flea or double pored
tapeworm”
-Most common tapeworm found in the small
intestine of dog and cat because they become
infected by ingesting the intermediate host --- the
flea
-The egg packets contain 15-20 eggs in each and
are seldom seen free in the feces. They may,
however, be readily expressed from the gravid
proglottids.
-Mostly diagnosed by finding proglottids in feces, in
their bed, your bed. “pooping maggots” “rice around
the anus” Can use tape
http://cal.vet.upenn.edu/paralab/labs/lab7.htm#02
Absolutes of Dipylidium
• Segments are longer than broad
• Contain 2 genital pores located
laterally. “double pored tapeworm”
Family: Taeniidea
•Genus: Taenia
•Species: pisiformis
--Eggs are “radially striated”
-Mostly diagnosed by finding proglottids
in feces, in their bed, your bed. “pooping
maggots” “rice”
-Contain lateral genital pore on the
gravid proglottids –
-Intermediate host = rabbit therefore
more common in dogs than cats
www.ksu.edu/.../
625tutorials/Tapeworm09.html
• Genus: Taenia
• Species: taeniaformis (cats), ovis
(dogs), hydratigena (dogs)
Taenia absolutes
• Segments are usually wider than
longer
• Segments contain 1 lateral pore
• ALL eggs are round and radially
striated
• All have to have an indirect lifecycle
• All produce eggs inside a basket that
is more fragile than dipylidium
• Host specific
All species of Taenia have
similar life cycles
• Genus: Multiceps
• Species: multiceps, serialis
The life cycle of this parasite involves warm blood
vertebrates as both the intermediate and definitive
hosts. The intermediate host is a rabbit or hare, and
the definitive host is a dog or other canine.
•Genus: Echinococcus
•Species: granulosus, multilocularis
-Host specific – either dog or cat. Any warm blooded animal
can serve as an I-host
-Eggs are similar in appearance to Taenia and Multiceps
Treatment of tapeworms
• Control the fleas
• No access to flesh or viscera on the IHost
• Medication
• Epsiprantel (Cestex®)
• Fenbendazole (Panacur®)
• Praziquantil (Droncit®)
Phylum: Nemahelminthes :
• Called Nematodes
• Contain the most prevalent parasites
• 560 Genera
• .5 million species
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Class: Secernentea
Family: Ascarid – “round worms”
Genus: Toxocara
Species: canis, cati
• Host specific singular
• Toxocara Canis: MOST PREVALENT
PARASITE OF DOG
• Common name: Canine Roundworm
• 4 possible routes of ingestion
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Direct ingestion
Passage in-utero (most common)
Paratenic transport
lactogenic
Toxocara canis
Clinical signs: mucoid diarrhea, poor
growth, abdominal pain, distended belly
Once ingested: hatch in the small intestine,
penetrate the mucosa, migrate through the
liver, pass through the heart, go into the
lungs, coughed up and swallowed, then
mature in the intestine within 4-6 weeks
Eggs are round with a “ropey” outer ring
(stippled exterior coat)
• Toxocara cati
• 3 routes of infestation
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Direct ingestion
Paratenic host
Lactogenic (most common)
DO NOT go inutero
Toxocara cati
Similar in appearance
to Toxocara canis
however, they are
smaller
Have the characteristic
pitted outer coat
Once ingested, follow
the same route as
Toxocara canis
Absolutes of Toxocara canis, cati
• The outer shell of egg will have a
ropey appearance
• The nucleus does or almost fills the
entire egg
• Shape of the egg, in general, is
considered round
The lifecycle of Toxocara is
very similar to that of Ascaris
•Genus: Toxascaris
•Species: leonina
•Found in dogs or
cats
Routes of ingestions are same as
Toxocara cati.
Oval shaped eggs, ropey appearance in
on the INSIDE of the shell
Nucleus does not fill the shell
Treatment of “roundworms”
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Fenbendazole (Panacur®)
Pyrantel (Strongid®)
Milbemycin oxime (Interceptor®)
Piperazine
• These parasites are difficult to
control. Must thoroughly clean
kennels, runs, yards. Very common
for small children to become infected
Order: Strongylida
• Family: Ancylostomatiidea
“hookworms”
• Genus: Ancylostoma
• Species: caninum
4 routes of infestation
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1. Direct ingestion
2. Skin penetration
3. In utero
4. lactogenic
• ***can penetrate skin in humans
causing “cutaneuos larval migrans”
Ancylostoma caninum
Can infest dogs, fox, coyotes,
wolves, raccoons, badgers
Have a smooth thin outer shell
and contain several cells that
quickly divide. Often called a
“morulated embryo”
Other Ancylostoma species
• Ancylostoma braziliense
• Found in dogs and cats
• Ancylostoma tubaeforme
• Found in cats
• Ancylostoma duodenale
• Found in dogs and cats
All hookworm species
have a similar
lifecycle
Another type of “hookworm”
•Genus: Uncinaria
•Species: stenocephala
•Common name: “cold
weather hookworm”
Found in dogs, cats, foxes,
coyotes, wolves
More prevalent in the NE United
States
Difference between Ancylostoma and Uncinaria
eggs
• Size - uncinaria eggs are larger
• Wall thickness – uncinaria walls are
thicker
• Location – uncinaria are typically
found in cold climates
Family: Stongyloides (same Phylum = nemahelmithes)
•Genus: Strongyloides
(commonly called
Nematodes)
•Species: stercoralis
•Common name:
“hookworm”
As it would appear in fecal
sample
Has both free-living and parasitic life cycles
Female is the parasitic one and reproduces
without fertilization
Females live embedded in the mucosa of the
small intestine
Treatment of “hookworm”
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Fenbendazole
Ivermectin
Milbemycin Oxime
Pyrantel
P: Nemahelminthes, C: Adenophorea, O: Adenoplida
•Family: Trichuroidea
•Genus:Trichuris
“whipworms”
•Species: vulpis
•Common Name: Canine
Whipworm
Easily identifiable by the “bi-polar” ends
Adult worms are shapes like a whip
One of the most simple life cycles
•Genus: Capillaria
•Species: hepatica
This parasite is found primarily in rodents,
although it has been reported in canines
and humans. As the parasite's name
implies, the worms live in the host's liver,
generally surrounded by a connective
tissue capsule.
Egss are typically darker in color than
Trichuris and smaller
Treatment of Whipworms
• Fenbendazole
• Ivermectin
• Milbemycin Oxime
Taxonomy check
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Kingdom = animala
Phylum = nemahelminthes
Class = secernentea
Order = spirurida
Family = filarioidea
• Genus: Dirolifaria “Heartworm”
• Species: immitus
• Dirofilaria causes “heartworm
disease” aka “Dirofilariasis”
• Blood parasite that lives in the
circulatory system of dogs and cats
Dirofilaria immitus (DI)
DI
• Infections occur in more commonly
in dogs than cats
• The worm(s) reside primarily in the
right ventricle and pulmonary
arteries
• Mosquito acts as the intermediate
host
It takes
approximately 85120 days for the
microfilariae to
mature
When the
microfilaiae reach
the heart, they
reach sexual
maturity in
approximately 6070 days.
Diagnosis of DI
• Identification of microfilaria in the
blood using various methods
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Capillary hematocrit tube
Knott’s test
Fresh blood/saline smear
Snap Test
Treatment of DI
• Use of an agent effective against
adult heartworms. The adult worms
and the microfilaria are eliminated
separately. No one medication kills
both. The adults are treated first
then a different treatment is used to
kill the microfilaria and migrating
larvae.
• Adulticide = thiacetarsamide
(Caparsolate)
• After the adulticide treatment and its
side effects are resolved (usually at
about 1 month post treatment), the
microfilaria are then eliminated with
one or another of two common
Heartworm preventatives, Ivermectin
(HeartGard) or Mibemycin oxime
(Interceptor). This will be done
approximately one month after the
adulticide treatment.
• www.thepetcenter.com
Heartworm Cont.
•Genus: Dipetalonema
•Species: reconditum
•(DR)
These ARE NOT clinically significant, although they may give elevated
eosinophil and leukocyte counts. Its importance, however is its
tendency to cause false positives in tests for circulating D. immitis
microfilariae
• DR is found in SQ tissues to develop
to sexual maturity
• Common, found throughout the midAtlantic United States, but its
transmission is not limited to warm
months.
• IH is the flea
Difference between DI and DR
• DI
• Slow/sluggish
• Coil and uncoil action
• Tail is straight
• DR
• Fast forward movement
• Snakelike
• Tail is bent or crooked
Phylum: Protozoa
• These are one celled animals, not
worms
• Do not produce eggs, produce cysts
• Cysts are tiny thin-walled sacs. Have
to scan on 40x.
• 2 most prevalent = Giardia, Coccidia
•Genus: Giardia
•Species: over 40
•2 forms
•Cyst: will find 99% of the
time
•Trophozoite: feeding or
growth stage
Cyst
• Have a thin outer wall and are
refractive to light which produce a
greenish glow around the edge
• Infective stage- these are zoonotic
and inverse zoonotic
• Transmission –
• drinking contaminated water
• or oral/fecal contact
Trophozoite
• Short lived if passed in feces
• Kite or tear-dropped shaped with
flagella
• Appear to have 2 eyes in them
Life cycle
Main Clinical symptoms
= odiferous diarrhea
Diagnosis
• Direct smear
• Saline smear
• Centrifugal flotation
Treatment of Giardiasis
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Metronidazole
Furazolidone
Albendazone
Cleanliness and disinfection with
ammonium compounds
Coccidiosis
•Genus: Isospora,
Eimeria
•In fresh feces, will locate the
unsporulated cysts.
•Hen shaped egg with one circle in it
•The outer rim is very refractive
•Report as “coccidia” since the
treatment kills both genera.
•Genus: Cryptosporidium
•Species: parvum
Cryptosporidium infections have been
reported from a variety of wild and
domesticated animals, and in the last six or
seven years literally hundreds of human
infections have been reported, including
epidemics in several major urban areas in the
United States.
Clinical symptoms include mild to severe
diarrhea and infection may clear on it’s own
•Genus: Sarcocystis
•Species: many
There are a number of species of
Sarcocystis, all of which have obligate two
host life cycles. In most instances the
intermediate host is a hoofed animal, and
many species of reptiles, birds and
vertebrates will serve as the definitive host.
•Genus: Toxoplasma
•Genus: gondii
•“toxoplasmosis”
Definitive host = cat
The intestinal phase occurs in cats only
(wild as well as domesticated cats) and
produces "oocysts." The extraintestinal
phase occurs in all infected animals
(including cats) and produces
"tachyzoites" and, eventually,
"bradyzoites" or "zoitocysts." The
disease toxoplasmosis can be
transmitted by ingestion of oocysts (in
cat feces) or bradyzoites (in raw or
undercooked meat)
Diagnosis of Toxoplasmosis gondii
• Recovery of oocysts or sporocysts in
feces
• In humans = blood test
Treatment of Tg
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Cleanliness
Removal on animal from premises
Furazolidone
Sulfadiazine/trimethoprim
Sulfadimethoxine
Prevention of consumption of raw
meat and contact with feces of cats