David S. Lindsay

Feline clinical parasitology.

Description: Although there are books available dealing with canine parasitology, there is at present no book detailing parasites that offers clinical information specific to felines. Cats differ significantly from dogs in their parasitic infections and infestations. Although dogs and cats do share a few parasites, the vast majority of the parasites of these pets are specific to either cats or dogs, not to both. This must–have reference offers an in–depth examination of feline parasites. Because of the immense worldwide popularity of cats and due to the amount of travel undertaken by cats and their owners, the authors have produced a book that is international in scope. Consequently, this exhaustive reference has strong appeal to practitioners and veterinary parasitologists in North America and around the world.

A new Hepatozoon species from dogs : Description of the causative agent of canine Hepatozoonosis in North America

A new species of Adeleina, Hepatozoon americanum, is described from the skeletal muscle, cardiac muscle, visceral organs, and blood of dogs (Canis familiaris) in the Southern United States. The organism was previously identified as Hepatozoon canis (James, 1905) Wenyon, 1926; however, differences in clinical signs, histopathological and serological findings, gamont size, and ultrastructure define the new species of Hepatozoon. Attempts to transmit the protozoan from infected dogs to nymphal Rhipicephalus sanguineus ticks, the definitive host of H. canis, were not successful.

Transplacental Transmission of a North American Isolate of Leishmania infantum in an Experimentally Infected Beagle

Leishmania infantum, an etiologic agent of zoonotic visceral leishmaniasis, is widespread among foxhounds in the United States. Although sand flies are widely distributed throughout the United States, epidemiological data do not support a major role for sand flies in the transmission of L. infantum in foxhounds in this country. Congenital transmission of human visceral leishmaniasis is reported in humans and might also occur in dogs. We have previously isolated L. infantum from Virginia foxhounds and used this isolate (LIVT-1) to experimentally infect beagles. Four female beagles, chronically infected with LIVT-1, were bred to a male beagle chronically infected with L. infantum chagasi. One beagle was able to maintain her pregnancy, and 4 puppies were delivered by cesarean section. One puppy was malformed and autolytic at delivery, and tissues were not collected or analyzed. The remaining puppies were killed at the time of cesarean section, and selected tissues were collected for parasite culture and PCR. Promastigotes were not cultured from tissues in any of the puppies. Leishmania sp. DNA was detectable by PCR in liver, bone marrow, and heart from all 3 puppies and in the spleen, lymph node, kidney, and placenta in 2 puppies. Placental tissue from the dam was PCR negative. This is the first report of maternal transmission of a North American isolate of L. infantum from an experimentally infected dog.

SURVIVAL OF TOXOPLASMA GONDII OOCYSTS IN EASTERN OYSTERS (CRASSOSTREA VIRGINICA)

Toxoplasma gondii has recently been recognized to be widely prevalent in the marine environment. It has previously been determined that Eastern oysters (Crassostrea virginica) can remove sporulated T. gondii oocysts from seawater and that oocysts retain their infectivity for mice. This study examined the long-term survival of T. gondii oocysts in oysters and examined how efficient oysters were at removing oocysts from seawater. Oysters in 76-L aquaria (15 oysters per aquarium) were exposed to 1 × 106 oocysts for 24 hr and examined at intervals up to 85 days postexposure (PE). Ninety percent (9 of 10) of these oysters were positive on day 1 PE using mouse bioassay. Tissue cysts were observed in 1 of 2 mice fed tissue from oysters exposed 21 days previously. Toxoplasma gondii antibodies were found in 2 of 3 mice fed oysters that had been exposed 85 days previously. In another study, groups of 10 oysters in 76-L aquaria were exposed to 1 × 105, 5 × 104, or 1 × 104 sporulated T. gondii oocysts for 24 hr and then processed for bioassay in mice. All oysters exposed to 1 × 105 oocysts were infected, and 60% of oysters exposed to 5 × 104 oocysts were positive when fed to mice. The studies with exposure to 1 × 104 oocysts were repeated twice, and 10 and 25% of oysters were positive when fed to mice. These studies indicate that T. gondii can survive for several months in oysters and that oysters can readily remove T. gondii oocysts from seawater. Infected filter feeders may serve as a source of T. gondii for marine mammals and possibly humans.

Neospora Caninum Induced Abortion in Sheep

Bull 1 Bull 2 The respiratory infection in these bulls may have predisposed them to the iron intoxication. It has been previously Blood ammonia nitrogen 2.8 mg% NT* stated that inflammatory processes in the body result in a Creatine phosphokinase 8,740 IU/liter 4,720 IU/liter decrease in the total iron-binding capacity of the serum, which Aspartate aminotransferase 1,390 IU/liter 2,450 IU/liter should increase the susceptibility to parenterally adminis-

Central Nervous System Neosporosis in a Foal

Cutaneous or subcutaneous cysts of all types are considered rare in cats. A literature search yielded no reports of cutaneous or subcutaneous dermoid cysts in cats. The structures reported here were histologically compatible with the description of the dorsal midline structures in dogs but, because they did not communicate with the spinal canal, these cysts posed no danger or potential danger to the animal from central nervous system infection. These structures were present in the flank instead of along the dorsal midline, possibly as a result of faulty embryologic fusion of adjacent dermatomes. The dermoid cyst in cat no. 2, considering its young age, probably was a congenital disorder; however, cat no. 1 was 10 years old at the time of presentation. It was not known how long the cyst in cat 1 had been present or if it had grown in size immediately prior to presentation. Dermoid cysts have been classified according to depth of penetration of the sinus. Class I cysts extend from the skin to the supraspinous ligament, class II cysts do not extend as deeply but are connected to the supraspinous ligament by a fibrous band, and class III cysts are similar to class II cysts but have no connecting band to the ligament. A fourth class has been proposed, in which the cyst extends to the spinal canal and is attached to the dura mater. This class is analogous to the pilonidal sinus of human beings, which usually occurs in the coccygeal region. The term pilonidal cyst, which by definition means any cyst containing a tuft of hair, is usually used synonymously with the term dermoid cyst in veterinary medicine. Perhaps 1 reason for the confusion over the term dermoid cyst is that many deep anomalous structures can have structural components of epithelium and can be loosely termed dermoid cysts by pathologists. A recent textbook has subclassified these cysts in an effort to more clearly define each type from a histologic standpoint. In this classification system, dermoid cysts are considered a type of follicular tumor. More widespread application of the classification system may be helpful to pathologists and clinicians for separating benign lesions from those with potential for serious complications. The surgical treatment of dermoid cysts is straightforward and involves careful dissection of the cyst. Although dermoid cysts are reported to involve only the skin or subcutaneous tissues, the cyst in cat no. 1 was found isolated between muscle layers of the flank and the sinus in cat no. 2 extended to the peritoneum. When excision of the cyst involves creation of an abdominal wall defect, care should be taken to ensure that anatomic closure of the defect is accomplished to avoid subsequent herniation of abdominal contents.

Neospora Caninum- Associated Myocarditis and Encephalitis in an Aborted Calf

Neospora caninum is a recently recognized protozoan parasite, previously misdiagnosed as Toxoplasma gondii. 1,3,5-8 It can cause fatal myositis, encephalitis, and polyradiculoneuritis in transplacentally infected neonatal and adult dogs. Neospora caninum parasites have also been associated with abortion and neonatal disease in cattle? 6,11 The life cycle and source of infection are unknown. We report N. caninumassociated myocarditis and encephalitis in an aborted calf. A 2-year-old Shorthorn heifer aborted an &month-old fetus. The fetus was necropsied shortly after being aborted. The carcass was edematous with several liters of fluid present in pleural and peritoneal cavities. The liver was friable. Because of suspected heart disease, heart and liver, as well as portions of kidney, spleen, cerebrum, cerebellum, pons, and medula were fixed in 10% buffered neutral formalin. Paraffinembedded tissues were cut at 5 μm, stained with hematoxylin and eosin (HE), and examined. Portions of heart were embedded in methyl glycolate, and 2-3-μm sections were cut and stained with HE or periodic acid-Schiff (PAS) reaction. Portions of formalin-fixed heart were also processed for transmission electron microscopy. 10 Paraffin-embedded sections of heart and other organs were stained with T. gondii and N. caninum antisera. Blood was collected from the heifer, and the serum was examined for antibodies to Toxoplasma gondii using a direct agglutination test. The levels of selenium, copper, and nitrate were determined in liver homogenate (selenium, copper) and in aqueous humor (nitrate).” a 2 Routine bacteriological cultures of liver and heart were performed. Virus isolations were attempted” on liver homogenate in fetal bovine turbinate cell cultures. Microscopic lesions were seen in the heart, liver, and brain. The myocardial lesions consisted of multifocal areas of edema, hemorrhage, necrosis of myocytes, and infiltrations of neutrophils and mononuclear cells in and around myocytes and Purkinje fibers (Fig. l A-lD). There was also diffuse nonsuppurative pericarditis. Numerous intracellular tachyzoites were found in myocytes and were occasionally seen in Purkinje fibers. Tachyzoites in the heart were found indi-

Characterization of temperature-sensitive strains of Neospora caninum in mice

Temperature-sensitive (ts) strains of the Neospora caninum tachyzoites were selected by chemical mutagenesis and selection for growth at 32 C. Three ts strains and the parental, N. caninum wild-type strain, NC-1, were examined in the present study for their ability to cause disease in inbred BALB/c mice, outbred ICR mice, and chemically immunosuppressed ICR mice. In BALB/c mice, all 3 strains failed to induce clinical disease, whereas infection with the NC-1 strain caused central nervous system disease and death in some mice. No disease was observed in ICR mice inoculated with the 3 ts strains or the NC-1 strain. All immunosuppressed ICR mice inoculated with the NC-1 strain died, whereas no immunosuppressed mice inoculated with the NCts-4 strain and only 1 of 5 mice inoculated with the NCts-8 and NCts-12 strains died. The NCts-4 and NCts-12 strains reverted to a wild-type phenotype when grown at 37 C. Vaccination of BALB/c mice with live, but not frozen NCts-8 strain tachyzoites induced significant (P < 0.05) protection following NC-1 strain challenge.

Detection of Neospora Caninum in Tissue Sections Using a Murine Monoclonal Antibody

A murine monoclonal antibody (MAb 6G7), isotype IgG2a, produced against tachyzoites of Neospora caninum (isolate NC-l) reacted specifically with tachyzoites of N. caninum in an indirect immunofluorescent antibody test. MAb 6G7 did not react with tachyzoites of Toxoplasma gondii, sporozoites of Isospora suis, Eimeria bovis, or E. tenella, or merozoites of E. bovis in the indirect immunofluorescent antibody test. MAb 6G7 reacted positively with both tachyzoites and bradyzoites of N. caninum in an avidin-biotin peroxidase complex immunohistochemical test on formalin-fixed paraffin-embedded tissues. No reaction was observed with the following: tachyzoites and bradyzoites of T. gondii, T. gondii-like parasites, or Hammondia hammondi; bradyzoites of Frenkelia microti; schizonts and merozoites of Sarcocystis-like organisms; schizonts, sarcocysts, and oocysts/sporocysts of S. cruzi; schizonts and merozoites of S. canis; schizonts of S. hirsuta, S. tenella, and S. capracanis; merozoites of S. neurona and S. neurona-like organisms, E. bovis, or Haemoproteus sp.; bradyzoites and merozoites of S. montanaensis; bradyzoites of S. odocoileocanis, S. cruzi, and S. tenella; meronts, sexual stages, and caryocysts of Caryospora sp. and C. bigenetica; micromerozoites, macromerozoites, and schizonts of Hepatozoon canis; sporozoites, sexual stages, and oocysts of Cryptosporidium parvum and C. baileyi; trophozoites of Monocystis Zumbrici, Tritrichomonas foetus, and Balantidium coli; tissue cysts and bradyzoites of Besnoitia sp. and B. jellisoni; amastigotes of Leishmania sp.; and trophic theronts of Ichthyopthirius multifilis. MAb 6G7 reacted with tachyzoites and bradyzoites of N. caninum in natural and experimental infections in dogs, cattle, mice, rats, sheep, and goats, indicating that host origin of the tissues did not affect the performance of the test.

EXPERIMENTAL INFECTION OF CATTLE WITH A FELINE ISOLATE OF TRITRICHOMONAS FOETUS

Tritrichomonas foetus is the causative agent of bovine trichomoniasis, a sexually transmitted disease in cattle that can result in large profit losses for cattle producers. Increasing reports have suggested that T. foetus is also the causative agent of large-bowel diarrhea in cats. To determine if the trichomonads recovered from the reproductive tract of cattle and the large intestine of cats can thrive in the same host, 2 groups of virgin Angus heifers were inoculated with T. foetus. The first group of heifers was inoculated with a bovine T. foetus isolate cultured from a naturally infected cow, and heifers in the second group were inoculated with T. foetus organisms cultured from the feces of a naturally infected cat. Over an 11-wk period, vaginal, cervical, and uterine mucus samples were analyzed, along with a single transcervical uterine biopsy sample, to determine organism and disease presence. The mucus and biopsy samples collected from each group indicate that the disease caused by feline and bovine isolates of T. foetus are comparable, but not identical.