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 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 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 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 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.

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 u X u and have a marked "shoulder" or "ridge" surrounding the operculum.

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

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” 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 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

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 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 I- Host Medication Epsiprantel (Cestex®) Fenbendazole (Panacur®) Praziquantil (Droncit®)

Phylum: Nemahelminthes : Called Nematodes Contain the most prevalent parasites 560 Genera.5 million species

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 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 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” 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 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” 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 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 days for the microfilariae to mature When the microfilaiae reach the heart, they reach sexual maturity in approximately days.

Diagnosis of DI Identification of microfilaria in the blood using various methods 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.

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 mid- Atlantic 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 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 Cleanliness Removal on animal from premises Furazolidone Sulfadiazine/trimethoprim Sulfadimethoxine Prevention of consumption of raw meat and contact with feces of cats