Reindeer on a strollA blood sample from a reindeer in Iowa was submitted to a parasitology laboratory in Oklahoma for identification of a suspected hemoparasite (Image 1_arrow). The reindeer had a history of travel between Minnesota, Wisconsin, and Iowa. CBC analysis revealed hematocrit of 10%. Thanks to Dr. Claire B. Andreasen for providing the sample and Dr. Kathryn Duncan, Oklahoma State University, for sharing this case.  Image 1: Suspected hemoparasite on blood smear Theileria cervi. This protozoan parasite can infect cervids through the bite of Amblyomma americanum, the lone star tick. To date, few reports exist documenting disease from this intracellular parasite and it is generally considered nonpathogenic. Cases when animals were reported to have clinical signs, they were either malnourished or co-infected with other pathogens. The identification of this parasite was molecularly confirmed by PCR. Stuck on youThe following video (liver) was taken during necropsy examination of a 2-year-old cow from eastern Texas. What is your diagnosis? Fasciola hepatica or liver flukes. These platyhelminths live in the bile ducts of ruminants and other mammalians. The adults produce large eggs that are excreted with feces. The eggs develop into a larva called miracidium inside the egg and then swims out to find a snail intermediate host. When fully developed the cercaria leaves the snail’s tissues and encysts as metacercaria in grass and pastures. After ingestion the young fluke penetrates the wall of the intestine and crosses the peritoneal space to the hepatic parenchyma, several weeks later the young flukes enter the bile ducts where they mature into adult parasites. The most common form of liver fluke diseases in cattle is chronic and rarely fatal, most animals develop anemia, decreased weight gain and submandibular edema. The acute form is more common in camelids and sheep in which the parasites can cause traumatic hepatitis by migration of the juvenile parasites. New Year's fun findingA 2-year-old female mule deer (Odocoileus hemionus) from western Oklahoma was submitted to the Oklahoma Animal Diseases Diagnostic Laboratory, for necropsy. During examination the following specimens were recovered from the cervical region.  Image 1: Adult nematode recovered from the cervical region of a deer Eleaphora shneideri female (F) and male (M), not associated to the cause of death in this case. (Image 2 and Image 3)
Image 2: Anterior end
Image 3: Posterior end of male nematode with cuticular thickenings (red arrow) and spicules (black arrow) These nematodes are common parasites of mule deer and deer in the US. Adults live in the carotid arteries or their branches; females measure an average of 10 cm and males 7 cm.
E. shneideri are transmitted by Tabanid flies considered cyclodevelopmental hosts. Infective larvae migrate to the leptomeningeal arteries where they develop into young adults and further migrate to the carotid or maxillary arteries where they become adults, releasing microfilariae (average 250 µm in length) into the bloodstream. (Images 4-6). In mule deer E. shneideri is often asymptomatic, in sheep it can cause dermatitis of the head as a reaction to the microfilariae in the skin, also referred as “sore head”. In other atypical hosts such as moose or elk they can develop clinical eleaphorosis, characterized by obstructed blood flow, thrombosis and endothelial damage. Image 4: Microfilaria Image 5: Anterior end of microfilaria Image 6: Posterior end of microfilaria Oinkmas: A piggy Christmas storyA 4-month-old pig was brought for necropsy examination at the Oklahoma Animal Disease Diagnostic Laboratory. The pig had recently died along with 3 other pigs (same age). All had a history of anorexia, low fever and diarrhea. The other 3 pigs had traces of blood on feces. During gross examination, gastritis, enterocolitis and numerous small parasites in the intestine were observed (not recovered). No parasite eggs, oocysts or cysts were recovered during fecal centrifugation from colon content. Histological examination revealed colitis, lymphoplasmacytic, histiocytic, neutrophilic and eosinophilic, with crypt abscess, chronic, moderate and intraepithelial and intraluminal nematodes (Figure 1). Thanks to Drs. Clare Brown and Daniel Barrantes-Murillo for contributing to this case.  Figure 1: A. Intraepithelial and intraluminal nematodes (arrowheads). Hematoxylin and eosin (HE). Bar = 400 mm. B. Transversal sections of intraluminal parasites. BB = bacillary band, C = cuticle, HY = hypodermis, SN = stichosome nucleus. HE. Bar = 60 mm. C. Transversal sections of intraluminal parasite. BB = bacillary band, CA = cuticular annulations, HY = hypodermis, S = stichosome. HE. Bar = 60 mm. D. Transversal sections of intraepithelial parasites. Pseudocoelom (asterisks) and polycytous intestine containing uninucleate epithelial intestinal cells (UI). HE. Bar = 60 mm. E. Transversal sections of intraluminal parasite. Hologenic ovary (O), polymyarian coelomyarian muscle (asterisk) and polycytous intestine containing uninucleate epithelial intestinal cells (UI). HE. Bar = 60 mm. F. The lamina propria is moderately expanded by the infiltration of moderate numbers of lymphocytes, plasma cells, histiocytes and fewer neutrophils and eosinophils, with crypt abscess (asterisk). HE. Bar = 60 mm. Trichuris suis, commonly known as whipworms are trichinellid parasites that live embedded within the epithelial cells of the large intestine, especially the cecum. Severe T. suis infections in young swine cause catarrhal enteritis with diarrhea, anorexia, and retardation of growth. Control of this parasite depends on separating swine from source of infective eggs, while treatment has been successful using Fenbendazole or Dichlorvos. Not what it seems?A 4-month-old shorthair cat was presented to a clinic in Eastern Oklahoma with a history of lethargy and intermittent diarrhea during the past week. Abdominal tenderness was detected at clinical examination. A fecal sample was submitted to the Oklahoma Animal Disease Diagnostic Laboratory and the following was observed on fecal centrifugation with Sheather’s sugar solution (Image 1)  Image 1: observed on fecal centrifugation with Sheather’s sugar solution Toxocara cati eggs, this nematode parasite infects cats worldwide and can cause visceral larva migrans in humans. T. cati can be transmitted by ingestion of infective eggs, paratenic host and rarely via transmammary when the queen gets acutely infected by the end of the pregnancy. Eggs are dark brown and measure 65 x 75 µm. Occasionally, abnormal forms of helminth eggs are observed and are more often seen in Trichuris vulpis eggs. On this case, black arrows demonstrate the undersize and the triangular shaped egg. Unusual morphology has been associated with early infection, therefore, it is important to recognize the existence of malformed helminth parasite eggs and consider when diagnosing helminth infections. Eerie discoveryA 3-year-old French Bulldog, from Atlanta, GA with no history of travel outside the USA, was presented to a local veterinary clinic due to history of worm expulsion. The dog was on heartworm and flea preventive at the time of clinical exam and lives with 4 more dogs in a fenced backyard that has a small pond. Thank you to Dr. Michelle Cox for referring this case and to Dr. Lindsay Starkey and Rachel Smith (OSU) for submitting it to NCVP. Image 1 & 2: Worms collected Mesocestoides sp. belongs to the class Cestoidea. They can be diagnosed by the presence of mediodorsal genital pores and eggs (30 – 40 µM in diameter, Figure 3) that accumulate in the parauterine organ (Figure 4, black arrowhead).
Mesocestoides sp. infects dogs, cats and wild mammals by ingesting reptiles, amphibians, small mammals or birds containing the infective larval stage called tetrathyridium. The complete life cycle of this parasite has not been fully described but a cysticercoid larval stage preceding the tetrathyridium, is believed to develop in a coprophagic insect. Occasionally Mesocestoides can replicate in the peritoneal cavity of dogs producing anorexia, ascites, vomiting and diarrhea among others. Mesocestoides corti, can multiply asexually in the intestines of dogs. Image. 3: Eggs recovered Image 4: Parauterine organ (black arrow) |
