Crawling bugs on a pot-bellied pig
A 1-year-old, free-range, pot-bellied gilt on a farm in southern Georgia presented with pruritus. The owner noted "bugs" crawling on the pig skin.
Haematopinus suis is the only louse species found on swine. Since this louse is a large species which can reach 6 mm in length, and it is easily detectable by gross examination. Infestations tend to be more severe during colder months.
Many thanks for a case with nice photos and move to Dr. Susan E. Little, Oklahoma State University & Dr. Kelsey Paras, University of Georgia.
Persistent mite eggs in feces of a dog?
A fecal sample from an approximately 9-month-old, intact female, collie-mixed dog was submitted to the parasitology diagnostic laboratory for recheck evaluation post-treatment against persistent Dipylidium caninum and Sarcocystis spp. infection. This dog had been rescued and imported from Ethiopia to the United States 3 month prior.
Centrifugal fecal flotation with Sheather's sugar solution (specific gravity, 1.25) was performed and revealed a low number of Sarcocystis spp. sporocysts and a moderate number of fairly large, oval-shaped, amber-colored, arthropod-like eggs (Figure 1 & 2). The egg shell outer wall were smooth, semi-thickened, and the embryo appeared to have 2-4 short appendages with pairs of chitinous hook-like structures visible using fine focus adjustment of the microscope at 400x magnification (Figure 2 & 3). A tentative diagnosis of pseudoparasite, most likely mite eggs, was made.
Two weeks post-treatment against Sarcocystis spp. infection, a fresh fecal sample was submitted for fecal examination. The same arthropod-like eggs were still detected in a moderate to high number in addition to a low number of Sarcocystis spp. sporocysts.
Figure 1: 100x magnification
Figure 2: Focused on the outer egg shell wall. 400x magnification
Figure 3: Focused on internal structure. Two irregularly arranged chitinous claws were seen inside the egg. 400x magnification
Linguatula serrata eggs.
Linguatula serrata uses carnivores, canids and rarely felids, as definitive hosts. The adult parasite can be found in the nasal airway, frontal sinus and tympanic cavity. Herbivores, such as ruminants and lagomorphs, become infected by ingesting eggs shed in the feces or nasal discharge of infected carnivores and serve as intermediate hosts by harboring encysted larvae (nymphs) in the internal organs and lymph nodes. Definitive hosts become infected by ingestion of the nymphal stages found in infected intermediate hosts. The prepatent period of this parasite is approximately 6–7 months, and adults live in definitive hosts for about 15 months. Eggs passed in the feces or nasal discharges are immediately infectious to intermediate hosts. Humans become infected by ingesting either eggs excreted by definitive hosts or nymphs in raw, undercooked viscera of intermediate hosts. Although the prevalence of this parasite is thought to be worldwide, most cases have been reported in Africa, the Middle East, and southern Asia.
Yoko Nagamori, et al. 2019. A zoonotic parasite, Linguatula serrata, infection in a dog imported from Ethiopia to the United States. Veterinary Parasitology: Regional Studies and Reports, 16, 100273.
Enlarged gallbladder in a rat!????
A 2-year-old, spayed female, pet rat presented to the state diagnostic laboratory for necropsy after being treated for severe respiratory distress associated with left atrial thrombosis. During necropsy, a cystic structure was attached to the edge of the left medial liver lobe (Figure 1). The cyst was carefully dissected, and a single, 14-15 cm long, segmented worm was recovered (Figure 2 & 3).
Figure 3: Anterior end
Strobilocercus - Juvenile stage of Taenia taeniaeformis.
Taenia taeniaeformis is a common tapeworm found in cats following ingestion of infected rodents. Rodents can serve as an intermediate host by ingestion of eggs. In a rodent, the larva migrates through the intestine and then forms a cyst associated with the liver. Strobilocercosis is usually non-pathogenic and an incidental finding during necropsy examination.
Click on the following link to watch a video of a live strobilocercus in this case! www.youtube.com/watch?v=8sIE7ui0t-8
A 4-month-old intact, male, calf was found dead and submitted to the state diagnostic laboratory for necropsy. Per owner, he was acting weak for a while, but he seemed to gain strength after having hay, protein and sweet feed. A centrifugal fecal flotation revealed the following larva as well as high number of trichostrongyle type of eggs and Eimeria multiple species oocysts. Baermann test was also performed on the fecal sample and recovered the same larvae.
Dictyocaulus viviparus first-stage larva. Characteristic dark food granules are observed in the intestinal cells. Although D. filaria larvae have a small knob at the anterior end, D. viviparus larvae do not have it.
First-stage larvae are passed in the feces of the host, and infective third-stage larvae develop on pasture and are ingested while grazing.
Click on the following link to watch a video of a live D. viviparus adult worm and first-stage larvae!: www.youtube.com/watch?v=ZfitLJPpgjc
Reference: Zajac and Conboy, Veterinary Clinical Parasitology 8th edition.
Diarrhea in a newly adopted kitten
Approximately 4-month-old domestic short-haired, intact female cat showed up to a small animal clinic with a 2-day history of soft stools/diarrhea and occasionally bloody diarrhea. This kitty was adopted from a local animal shelter a week ago, and besides diarrhea, she has been active and seemed happy. A centrifugal fecal flotation with 33% zinc sulfate solution was performed.
Numerous round to slightly oval-shaped objects with a thin, smooth, clear wall were observed. Original magnification, x100 (with x10 objective lens).
Size difference was also observed. Some were bigger - approximately 40-45 x 30 um, and some were smaller - approximately 20-25 x 20 um. Also some contained only a single, round cell inside, but some contained 2 round cells instead. Original magnification, x400 (with x40 objective lens).
A few of them even showed more details inside. Original magnification, x600.
Cystoisospora spp. oocysts - the bigger one was C. felis and the smaller one was C. rivolta.
This protozoan parasite is commonly called as "coccidia" of dogs and cats although other parasites, such as Eimeria, Sarcocystis, Toxoplasma, and Neospora, also fall into this taxonomic group. When oocysts are freshly passed in feces, they typically contain a single, round cell (called "sporoblast"). Developing process (called "sporulation") occurs in the environment - oocyst with a single sporoblast (C. rivolta in photo #2) > sporoblast multiplies into 2 sporocysts (C. felis in photo #2) > each sporocyst contains 4 sporozoites with a single large, round residual body (photo #3).
Cystoisospora infection is commonly found in young cats, and most of the time cats are asymptomatic. However, when kittens are stressed out due to weaning, change of owner, new environment, etc., clinical coccidiosis can occur and cause diarrhea, abdominal pain, and in a severe case, bloody diarrhea and anemia.
Anne M. Zajac & Gary A. Conboy. 2012. Veterinary Clinical Parasitology 8th ed.
Flotation solution matters
A 3-month-old dog presented to Riverside Animal Hospital in Miami, FL with a three-day history of watery diarrhea. The dog is indoor/outdoor and has a 1 year old canine housemate. A centrifugal fecal flotation with Sheather's sugar solution (specific gravity 1.25) was performed and revealed numerous half-moon shaped objects.
A centrifugal fecal flotation with Sheather's sugar solution revealed numerous half-moon shaped objects in the entire slide. Original magnification, 400x.
A centrifugal fecal flotation was repeated using a 33% zinc sulfate solution (specific gravity, 1.18).
A Centrifugal fecal flotation with a 33% zinc sulfate solution. Now more Giardia cysts were observed on the slide and most cysts showed details. Original, 400x.
Many thanks for a great case with nice photos to Dr. Kamilyah R. Miller, Tuskegee University, College of Veterinary Medicine & Dr. Yoko Nagamori, Center for Veterinary Health Sciences, Oklahoma State University.
They are Giardia spp. cysts.
Since this fecal sample was taken from a dog it could either be Giardia duodenalis Assemblage C and/or D (G. canis).
There has been suspicions of Giardia being zoonotic, but current research is now questioning that theory -- Giardia may be more species specific, and may not be zoonotic.
It is important to note the difficulties of identifying Giardia cyst on centrifugal fecal flotation. When performing a fecal flotation, it is important to use a zinc sulfate solution (specific gravity of 1.18) allowing the cyst to float showing with more details of internal structures. The slide must be prepared and read immediately following the centrifugal flotation so not allow the cyst to collapse. The cyst will have a green hue to them when using a zinc sulfate solution, you must fine focus in and out to identify the distinguishing features that make up the Giardia cyst.
Have feedback on the cases or a special case you would like to share? Please email us. We will appropriately credit all submittors for any cases and photos provided.