A silent stowawayA one-year-old neutered male cat, originally from St. Kitts Island, was presented to a veterinary clinic in Oklahoma for a wellness examination. The cat was within normal physiological parameters, with unknown deworming history. A fecal centrifugal flotation revealed the following:  Trichuris felis egg. The feline whipworm is a rare finding in the USA, with most of the cases detected in the south of Florida. Cats native or with history of travel to tropical regions are occasionally found. As with other whipworms species, T. felis adults live in the cecum and colon, clinical signs are usually associated with heavy burdens and immune status of the host. Cats become infected by ingestion of infective eggs from the environment; therefore prompt fecal collection is important. Diagnosis is done by fecal flotation methods and by using the commercial antigen test that detects Trichuris vulpis of canids. Necropsy surpriseA 7 week-old intact male feline was submitted for necropsy examination to the Oklahoma Animal Disease Diagnostic Laboratory. As incidental finding during examination, the intestines were noticeably distended (Image 1). Further histological analysis of the small intestine revealed structures containing numerous organisms in different developmental stages (Image 2, 40X magnification).  Image 1: Distended intestine found upon necropsy.  Image 2: Histological section of the small intestine containing numerous organisms in different developmental stages (40X). Cystoisospora spp. is a common coccidian of cats, particularly young animals. Cats are definitive hosts and mammals and birds can act as paratenic hosts. Infected animals can display abdominal discomfort, inappetence, dehydration and watery diarrhea sometimes containing blood. Cystoisospora felis and Cystoisospora rivolta are the species infecting domestic cats and are commonly diagnosed by recovering the oocysts in fecal centrifugal flotations. Control should be focused on prompt removal of feces before oocyst sporulation occurs (infective stage). Prognosis on treated cats is usually good to excellent.
Image 2: White arrows are pointing microgamonts, light-blue arrow points a macrogamont and black arrow an immature oocyst The nasal passengerA mule deer (Odocoileus hemionus) from Oklahoma was submitted for necropsy examination to the Oklahoma Animal Disease Diagnostic Laboratory (OADDL). Incidentally, larvae were recovered from the nasal passages (Images 1 and 2).
eCephenemyia sp. larva stage 3 (L3)
Bee-like female flies deposit larvae (L1) in the nasal passages of cervids. L1s are covered by a gelatinous fluid that protects them from desiccation and supports their adhesion. After a diapause they develop into L2 and move to the choanas and pharynx and larynx where they cluster. Mature L3s move to the nostrils and when the host sneezes or coughs they drop to the ground to pupate and emerge as adults a few weeks later according to the environmental temperature and conditions. Clinical signs are associated with the narrowing of the upper airways and nasal mucosa irritation caused by the larvae. Secondary infections can occur. Observed clinical signs are coughing, sinusitis, nasal discharge and in some instances open mouth breathing. Heavy infestations can cause weakness and exercise intolerance. Diagnosis is by location on host and general morphology. L3s average 1 to 1.2 inches in length, they have V shape antenna lobes (image 3, arrows) and C shape posterior spiracles (image 2). 
Image 3: Arrows showing V shape antenna lobes. Trouble in the rumenA 2-year-old cow from central Oklahoma was submitted for necropsy examination to the Oklahoma Animal Disease Diagnostic Laboratory (OADDL). Incidentally, the following specimens (~ 1 cm long) were collected from the rumen (Image 1).  Image 1: Specimens collected from the rumen, (~ 1 cm long). Cotylophoron sp., originally described by Fishoeder in 1901, belongs to the family Paramphistomidae with similar characteristics to Paramphistomum sp. In 1910, Stiles and Goldberger distinguished these two genera by a single characteristic, the presence of a genital sucker in Cotylophoron sp. Both have an oral sucker and a posterior sucker (Images 2 and 3). Paramphistomids are parasites of ruminants requiring a snail as first intermediate host to complete their life cycle. In the USA, they have been associated with diarrhea, dullness, and loss of body condition in buffalo and cattle in southern USA. Diagnosis in live animals depends on detection of eggs by fecal sedimentation, when adults are developed.
Image 2: Oral sucker. Image 3: Posterior sucker. Sheep under siegeA fecal sample from a one-year-old goat from central Oklahoma was submitted to the Parasitology Diagnostic Laboratory (OADDL) to perform a fecal egg count (FEC) and a fecal culture for parasite identification. A history of intermittent watery diarrhea and a FAMACHA score of 3 was provided in the anamnesis. The McMaster FEC result was 1,650 EPG, and the majority of larvae recovered after 9 days of fecal culture are shown in image 1 (~580 µm length).  Image 1: Larvae recovered from culture after 9 days, (~580 µm length). Chabertia ovina is a parasite that infects the colon of ruminants but mostly reported in sheep. The adults have a large buccal capsule without teeth. The adults can cause local bleeding and diarrhea leading to weight loss and anemia.
C. ovina larvae can be morphologically differentiated from other parasite larvae by the sheathed tail length, number of intestinal cells, and total length. C. ovina larvae measure <750 µm, the sheathed tail is ≤150 µm (image 2, black arrow) and the number of cells ranges from 28-32 rectangular cells (image 3, black arrow). This case seems unusual as the majority of caprine fecal larval cultures are typically overrepresented by Haemonchus contortus larvae. Image 2: Sheathed tail is ≤150 µm (black arrow). Image 3: Intestinal cells ranges from 28-32 rectangular cells (black arrow). Restless ruminantThe following flies were found on an open wound from a cow in southcentral Oklahoma. No larvae were observed by the attending veterinarian.  Cochliomyia macellaria, the secondary screwworm. These flies belong to the Calliphoridae family within the Dipetera order. Adult flies live up to 6 weeks and lay 50 to 200 eggs which, depending on air temperature, can hatch in a day. Larvae feed on carrion and upon maturity they move to a pupation area usually in the topsoil. Pupation lasts 7 to 10 days.
Clinical relevance: Fly larvae can infest the tissues of living animals causing myasis and potentially transmiting bacteria and viruses. Additionally, these flies could be morphologically confused with Cochliomyia hominivorax, the primary screwworm, which is currently absent in the USA. Adults can be differentiated by the length of the thoracic stripes where in C. macellaria they are the same length while in C. homnivorax the middle stripe is shorter than the outer stripes (white arrows on image). 
|
