Internal Parasites

Asst. Prof. Dr.Iman Daham Al-Maula Department of Internal & Preventive Medicine College of Veterinary Medicine

Collection and Submission of Samples . Diagnosis of parasitic infections depends on several factors , Such as:-

1- Collection of the sample . 2- Transport of the sample to the laboratories 3-Methods of laboratory evaluation . * Important factors to be considered in the diagnosis of and the Interpretation of the results are .

1- Age of the Host . 2- Previous exposure to parasites ( resistance ) 3- Time of the Year ( spring rise ) . 4- Physiological relationship ( par parturient rise ) . 5-Geographical location . 6- Previous use of anthelmintics . 7- History of clinical disease , and 8- Other considerations .

* Fecal Samples Feces must be fresh for accurate results , as feces age , A diagnosis is complicated because many parasite egg develop and hatch in to larvae . Contaminants such as free – living soil Nematodes , Fly larvae , Mite , and other arthropods , often invade and complicate a diagnosis . * Stored of Fecal Sample At least 10 of fresh feces should be collected . If sample are more than Two hours old , sample should be stored at 4 degree until examined . Many parasite stages can be stored at 4degree for at least 2months with minimal development Fecal Samples are best stored and sent in small plastic sandwich bags , plastic containers , disposable laboratory gloves turned inside out . Sample can be stored indefinitely in 10 % Formalin ( one part feces , nine 10 % formalin ) . Storage by Freezing is very inefficient . Storage in 70 % Ethyl alcohol or 100 % Methyl alcohol . * Spurious parasites : Pseudo parasites ( False parasites ) When examining fecal smear or Flotation preparation A wide variety of extraneous material is encountered . ( objects sometimes mistaken either for parasites or for generative products of parasites ) . Such as : Plant cell , Plant hair , Seed fibers , Starch granules , Protein particles , Vegetable cells , Fat droplets , Oil droplets , Air bubbles , Scratches on slide , Plant spring cell , Pollen grains , Fungus and Yeast spores .

* Types of Parasites Common Internal parasite ,called End parasites , live within an , these parasite derive their nutrition and protection at the expense of the infected animal , which is called the host . The various internal parasites have many different life cycle The host that harbors the adults , mature or sexual stages Of a parasite is called the Definitive host .The Dog is the definitive host for Dirofilaria immitis Adult male and female (Heart worm) are found in right ventricle & pulmonary arteries of the dogs heart. The host that harbors the larval , or asexual stages of a parasite is called Intermediate host . The Mosquito is the intermediate host for D. immitis , first , second , and third larval stages of D. immitis are found within the mosquito intermediate host .

Protozoa (unicellular organisms ) Protozoa are unicellular , or one –cell , organisms some of which may be parasitic in domestic . These protozoans can infect a variety of tissue site within the definitive host . The most common sites for their detection are in Blood samples called Blood protozoa or Hemoprotozoa , or within fecal sample , called Intestinal protozoa . The protozoans life cycle may be either Simple or complex . Hemoprotozoa : are found in erythrocytes within stained blood smear Tick usually serve as intermediate host and transmit the RBC containing Babesia bigemina is Tear – shaped or Pear shaped ( hemoprotozoa ) found within RBC infected. Cattle . Transmitted by Boophilus annulatus .

* Babesia bigemina Is an intracellular parasite , found within the RBC of cattle , this parasite is a large Piroplasm , 4_ 5 um long by 2 um wide . It is characteristically pear shaped and occurs in pairs , forming an acute angle within the RBC . The intermediate host for this protozoan parasite is the Tick Boophilus annulatus .

* Trypanosoma Trypanosoma another Hemoprotozoans . Found within RBC . Extracellular and swim within the blood , they are 3-10 times as long as an RBC is wide and are banana shaped they have a lateral undulating and a thin , whip like tail (flagellum) used Swimming . Transmitted by blood – feeding Arthropods . * Eimeria Identification of individual species of Coccidia is often difficult because their Oocysts are so similar in size and shape . Two most common species of Coccidia in cattle : Eimeria bovis & Eimeria zurnii , can be differentiated on a standard fecal flotation . Oocysts of E . bovis are oval . Have a micro Pyle and measure 20 -28 um . Whereas those of E. zurnii are spherical , lack the micro Pyle and measure 15-22. Oocysts are recovered on fecal flotation * Cryptosporidium Is another coccidian parasite , that parasitizes the small intestine of variety of animals . Including Cattle, Sheep , and Goats . Sporulated Oocysts in the feces are color less and transparent and are extremely tiny , only to 5.0 um in diameter . Diagnosis is by standard fecal flotation and stained fecal smears . ** Trematodes ( Flukes ) The Trematodes also called ( flukes ) are , unsegmented , Leaf- shaped bodies . Adult flukes found in the intestinal tract the liver or even the * Life cycle Flukes lay eggs Passed in the feces .The end portion of many fluke eggs has a small cap ,lid or door . This structure is called an operculum . Within egg is larval stage known Meracidium hatches and exits the egg is through the operculum this stage penetrates first intermediate host (snail) Meracidium develops Sporocyst then produced Tiny called Rediae many produce internal cercariae exits the snail one of three pathways to inter the definitive host develop Metacercaria and ingested by host . And second host . ** Flukes of veterinary importance : of Cattle and Sheep( ) . Fascioloides magna , . The fluke of Dog and Cats ( kellicotti ) . Eggs of Trematodes ** Cestodes ( Tape worms ) Also Flatworm . Also hermaphroditic , segment connected, divided in to a long of proglottides like train – car behind Scolex ( head ). Tapeworm attaches to the wall of the hosts intestine, most tapeworm release their proglottides one at a time or short chains in to the feces. Proglottides can be observed with the naked eye , few tapeworm release eggs directly from the worms uterus. Proglottids often contain eggs passed feces eggs contain Hexacanth embryos , with six hooks intermediate host ingests hexacanth grows in the tissues to bladder worm stage which is a Fluid – Filled larval stage the definitive host becomes infected by ingesting the intermediate host contain bladder worm larval stage Tapeworm that develop in to the bladder worm stage in the intermediate host are the : Canine taeniidae tapeworm (Taenia pisiformis) & the Coenurus tapeworm ( Multiceps malticeps ). In some tapeworm ( ) and (Echinococcus multilocularis ) . The larval stage within the vertebrate host is Hydatid cyst . The intermediate host is an Arthropod such as Flea or grain Mite . The hexacanth embryo develop in to a microscopic larval stage known as ( cysticercoid stage ) is tiny and contain a small fluid – filled space Definitive host become infected by ingesting the intermediate host contain cysticercoid larval stage:- Dipylidium caninum tapeworm in Dogs and Cats.

Cestodes ** Nematodes ( Roundworms ) Is called roundworms , and are one of the most important groups found in any tissue including : intestine , skin , lung , kidney , urinary bladder , nervous tissue , musculature and blood . Nematodes group have diverse , complicated life cycles .separate sexes (male and female ) .eggs or larvae recovered from the feces , eggs infecting the kidney or urinary bladder may be recovered the urine . Example : * Intestinal nematodes Found in Dogs , include large roundworms ( and Toxocara leonina ). : Ancylostoma caninum . Whipworm : Trichuris vulpis . * Urinary roundworm : include canine kidney worms : Dioctophyma renale * Respiratory roundworm : include the lung worms of Cattle and Sheep ( Dictyocaulus spp . And Muellerius capillaris . Nematodes of the blood vasculature are special group , which the Heart worm of Dogs : Dirofilaria immitis )

Adult female heartworms give birth to small worm like prelarval ( embryonic ) stage called Microfilaria . The Microfilaria may be observed in a peripheral blood smear and are approximately 310 um long . Within the Mosquito , develop in to infective Third – stage larvae . These infective larvae are transmitted to other animals by the infected mosquitoes . Eggs of Eggs of Trichuris Microfilaria Parasites of the Eye and Adnexa Nematodes ( Roundworms ): californiensis is eye worm of Dogs and Cats , adult can be recovered from the conjunctivas sac and lachrymal duct . ** Type of strongyl like eggs

Group of ( 7 ) type of parasitic type ova of Nematodes Similar morphologically . These include 1-7 .

1- Oesophagostomum columbianum 2- Strongyloides papillosus 3- Bunostomum . spp 4- axei 5- Haemonchus contortus 6- Chabertia ovina 7-Ostertagia ostertagi