PRESENTATION
BROCHURE Guadalupe Mirรณ
Dwight D. Bowman
ATLAS of PARASITOLOGICAL DIAGNOSIS in Dogs and Cats [ VOLUME I: ENDOPARASITES ]
ATLAS of
PARA TOLOGICAL DIAGNOSIS in Dogs and Cats [ VOLUME I: ENDOPARASITES ] Guadalupe Mirรณ Dwight D. Bowman
Guadalupe Miró
ATLAS of
PARA TOLOGICAL DIAGNOSIS in Dogs and Cats
ATLAS of PARASITOLOGICAL DIAGNOSIS in Dogs and Cats [ VOLUME I: ENDOPARASITES ]
Volume I: Endoparasites
Dwight D. Bowman
Atlas of parasitological diagnosis
[ VOLUME I: ENDOPARASITES ] Guadalupe Miró Dwight D. Bowman
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AUTHORS: Guadalupe Miró and Dwight D. Bowman. FORMAT: 22 x 28 cm. NUMBER OF PAGES: 128. NUMBER OF IMAGES: 230. BINDING: hardcover.
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This up-to-date, descriptive atlas dedicated to the main endoparasites of dogs and cats is an invaluable tool for practicing veterinarians given the importance of these parasites in small animals. The authors, renowned specialists in the field, discuss the most salient aspects of each parasite and use visual aids to describe in practical terms the best means of detection and treatment. The standout feature of the atlas is its diagnosis-oriented format; each plate is divided into four closely related sections, aiding interpretation of the content and making this atlas an essential reference in the field of small animal parasites.
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Atlas of parasitological diagnosis. Volume I: Endoparasites
Presentation of the book Parasitology is one of the key areas of study in the veterinary industry, as reflected by steady annual increases in both investment and research in this field. Despite the progress made in recent decades, the incidence of parasitic diseases remains high, and parasitic infections account for a significant proportion of consultations in small animal veterinary clinics. The mechanisms developed by many parasites to evade the host immune response and the increase in resistance to currently available antiparasitic agents have led to significant levels of prevalence and incidence. This underscores the need for improvements in the detection and treatment of these pathologies, and in prevention and control strategies, in order to minimise the impact of these parasites on both animals and humans, as several of these diseases can be transmitted to humans. The main purpose of this atlas is to provide key diagnostic clues to facilitate the detection of the most common parasites in small animals, as well as less commonly diagnosed diseases. This first volume exclusively covers endoparasites of dogs and cats. This atlas is unique in its clear diagnostic approach, and is thus an essential reference for veterinarians in their daily practice. This approach is evident in the layout of the plates, which contain sections on the aetiological, epidemiological, clinical, laboratory and post mortem diagnosis of each parasite. In summary, this atlas is a highly practical and educational tool that aids the diagnosis and prevention of parasitic diseases of small animals.
The authors Guadalupe Miró
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Guadalupe Miró received her bachelor´s degree and PhD in Veterinary Sciences from the Complutense University of Madrid (UCM). She was awarded a diploma from the European Veterinary Parasitology College (EVPC) and is Professor of Parasitology and Parasitic Diseases at the Department of Animal Health of the Faculty of Veterinary Medicine, UCM. She heads the Parasitic and Infectious Diseases Clinic of the Veterinary Hospital in Madrid and is a founding member and current President of LeishVet, the European expert group on canine leishmaniasis. She is the Spanish representative for the European Scientific Council for Companion Animal Parasites (ESCCAP) and President of the Spanish delegation (ESCCAP Spain). Author of numerous publications and scientific papers on infectious and parasitic diseases of small animals, she specialises in the sanitary control of feline and canine communities, and has conducted research on various zoonoses including leishmaniasis, babesiosis, toxoplasmosis and giardiasis. She directs the diagnostic and research laboratory Pet Parasite Lab at UCM.
Atlas of parasitological diagnosis. Volume I: Endoparasites
Dwight D. Bowman As a parasitologist, the focus of Dr. Bowman’s research has been on the biology of parasitic infections, testing of various agents for efficacy against parasites, disinfection of parasites in manures and sewage sludges, and improved diagnostics. Dr. Bowman graduated with honors in Biology from Hiram, College in Hiram, Ohio, in 1974. He received his MS and PhD degrees in parasitology from Tulane University in New Orleans, in 1976 and 1983, respectively. He was a postdoctoral scientist/lecturer at the School of Veterinary Medicine of the University of Wisconsin Madison from 1984 to 1987. He joined the faculty of the College of Veterinary Medicine at Cornell University, Ithaca, NY, in 1987, and is currently a Full Professor in Parasitology. He teaches courses in the veterinary, graduate, and undergraduate curricula of the University. In 2008, he was awarded the Distinguished Veterinary Parasitologist Award by the American Association of Veterinary Parasitologists. In 2009, he was awarded the Chancellor’s Award for Excellence in Teaching from the State University of New York. In 2009, he was also awarded Cornell University’s College of Veterinary Medicine’s first Community Service Award, and a recipient in 2010 of the Kaplan Family Distinguished Faculty Fellowship in Service-Learning. He is an honorary Diplomate in the Parasitology section of the American College of Veterinary Microbiologists. He is currently president of the American Association of Veterinary Parasitologists. He was a founding member of the Companion Animal Parasite Council which officially began in 2002, and has just completed a two-year term as president. He is author of 5 textbooks on parasitology including Georgis’ Parasitology for Veterinarians. He has published around 200 peer-reviewed papers on the topics of veterinary parasitology, and in addition to being an ad hoc reviewer for over 20 journals, serves or has served on the Editorial Boards of Journal of Zoo and Wildlife Medicine, Comparative Parasitology, Veterinary Parasitology, International Journal for Parasitology, and the Compendium of Continuing Education for the Practicing Veterinarian.
ATLAS of
PARA TOLOGICAL DIAGNOSIS in Dogs and Cats [ VOLUME I: ENDOPARASITES ] Guadalupe Mirรณ Dwight D. Bowman
Table of contents 1. Protozooses Coccidiosis sensu stricto (Cystoisospora spp.) Toxoplasmosis (Toxoplasma gondii) Neosporosis (Neospora caninum) Cryptosporidiosis (Cryptosporidium spp.) Giardiosis (Giardia duodenalis) Trichomonosis (Tritrichomonas foetus) Leishmaniosis (Leishmania infantum) Trypanosomosis (Trypanosoma cruzi and Trypanosoma evansi) Hepatozoonosis (Hepatozoon spp.) Piroplasmosis (Babesia spp., Theileria spp. and Cytauxzoon) Cytauxzoonosis (Cytauxzoon felis)
2. Cestodoses Taeniosis (Taenia spp.) Echinococcosis (Echinococcus spp.) Dipylidiosis (Dipylidium caninum) Other cestodoses (Joyeuxiella spp., Mesocestoides spp., Spirometra spp. and Diphyllobothrium latum)
3. Trematodoses Alariosis (Alaria alata) Opisthorchiosis (Opisthorchis tenuicollis) Heterobilharziosis (Heterobilharzia americana) Platynosomosis (Platynosomum fastosum)
4. Nematodoses Ascarididiosis (Toxocara spp., Toxascaris leonina and Baylisascaris procyonis) Ancylostomatidosis (Ancylostoma spp. and Uncinaria stenocephala) Trichuriosis (Trichuris vulpis and Trichuris serrata) Capillariosis (Capillaria aerophila) Strongyloidosis (Strongyloides stercoralis) Dirofilariosis (Dirofilaria spp.) Other filarioses (Acanthocheilonema spp. and Cercopithifilaria spp.) Angiostrongylosis (Angiostrongylus vasorum) Aelurostrongylosis (Aelurostrongylus abstrusus) Other pulmonary nematodoses (Filaroides spp., Crenosoma vulpis and Troglostrongylus spp.) Thelaziosis (Thelazia callipaeda and Thelazia californiensis)
5. Other parasitic infections Spirocercosis (Spirocerca lupi) Trichinellosis (Trichinella spiralis) Onchocercosis (Onchocerca lupi) Cuterebrosis (Cuterebra spp.) Linguatulosis (Linguatula serrata)
6. References 7. Looking through the microscope
PROTOZOOSES
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ATLAS OF PARASITOLOGICAL DIAGNOSIS IN DOGS AND CATS
Coccidiosis sensu stricto
ETIOLOGY (Cystoisospora spp.) The oocysts become infectious after sporulation in the environment.
ENDOPARASITES
ETIOLOGIC DIAGNOSIS The dog and the cat can be parasitized by four species of Cystoisospora. The species can be differentiated depending on host specificity, morphometry and sporulation of the oocysts (two sporocysts containing four sporozoites). Cystoisospora species are ubiquitous, and oocysts can be found in the feces of clinically healthy and sick animals. Patency develops within a period of 6–10 days after infection, when the oocysts are released with the feces of parasitized animals and enter the environment. After 1–4 days, the oocysts in the environment become infectious. Infection occurs by the fecal-oral route, through the ingestion of sporulated oocysts. Several animals, including rodents and ruminants, can act as paratenic hosts after ingesting infective oocysts.
EPIDEMIOLOGY Most clinically diagnosed cases occur in animals younger than 4 months.
CLINICAL Commonly diarrhea, i.e., multiple loose, watery or pasty stools that may contain mucus or blood. Figure 1. Unsporulated oocyst of Cystoisospora canis (34–40 × 28–32 µm) (40x). © G. Miró.
LABORATORY Stool analysis by flotation to distinguish oocysts.
POST MORTEM Histology to differentiate schizonts, gamonts, oocysts and intermediate stages. Figure 2. Unsporulated oocyst of Cystoisospora felis (38–51 × 27–29 µm) (10x). © G. Miró.
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PROTOZOOSES
Coccidiosis sensu stricto
Species that infect dogs
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EPIDEMIOLOGICAL DIAGNOSIS
Cystoisospora canis 34–40 × 28–32 µm (Fig. 1).
Cystoisospora ohioensis 20–27 × 15–24 µm.
Species that infect cats Cystoisospora felis 38–51 × 27–29 µm (Figs. 2 and 3).
Cystoisospora rivolta
Coccidiosis is typically a disease of very young animals or those animals with immune system disorders. It is usually associated with overcrowding, stress, poor sanitation (pet shops, kennels, shelters, animal facilities, etc.), concomitant diseases, malnutrition and any state of immunosuppression. Age is a predisposing factor, as disease is most severe in the youngest animals. Primary infections usually occur during the lactation period from the third to the eighth week of life. Therefore, most of the cases diagnosed in puppies and kittens corresponds to animals younger than 4 months of age. The oocysts remain infective for several months in the environment and can accumulate in kennels and shelters with a very high density of animals.
21–28 × 18–23 µm (Fig. 4).
b a
b
Figure 3. Oocysts sporulated (a) and without sporulation (b) of Cystoisospora felis (38–51 × 27–29 µm) (40x). © G. Miró.
b a
Figure 4. Oocysts sporulated (a) and without sporulation (b) of Cystoisospora rivolta (21–28 × 18–23 µm) (40x). © G. Miró.
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ATLAS OF PARASITOLOGICAL DIAGNOSIS IN DOGS AND CATS
ENDOPARASITES
CLINICAL DIAGNOSIS Diarrhea from coccidiosis is typical of small intestinal dysfunction with increased water content or tarry stools that occasionally may have mucus or blood as a result of the destruction of the intestinal epithelium by the massive multiplication of the parasite (Fig. 5). Young animals may also show lethargy, weight loss, meteorism, dehydration, and vomiting. Clinical signs may precede the appearance of oocysts, particularly in acute infections.
Figure 5. Pasty feces of a cat infected with Cystoisospora felis. © G. Miró.
LABORATORY DIAGNOSIS Diagnosis is based on the demonstration of oocysts of different sizes, depending on the species; in the feces of suspect animals by a stool analysis by flotation (patency period is about 4 weeks). The number of oocysts per gram of feces should be high, since their simple presence in a stool does not mean the presence of disease. On some occasions, Eimeria oocysts (four sporocysts, each of which contains two sporozoites) ingested by dogs and cats in the environment, by coprophagia, or through the ingestion of prey (Fig. 6) can be found. Figure 6. Sporulated oocyst of Eimeria spp. (40x). © G. Miró.
POST MORTEM FINDINGS These protozoa develop in enteroepithelial cells of the small intestine, causing enteritis (Fig. 7). Schizonts, gamonts, oocysts and intermediate stages in parasitophorous vacuoles within the cytoplasm of enterocytes can be differentiated in histological sections stained with hematoxylin-eosin stain. Direct smears or imprints of the small intestine stained with Wright or Giemsa stains can also be made to identify the sporozoites.
Figure 7. Enteritis of the small intestine in a cat due to Cystoisospora spp. © G. Miró.
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PROTOZOOSES
PROTOZOOSES
Toxoplasmosis
ETIOLOGY (Toxoplasma gondii ) Infective forms: sporulated oocysts, tachyzoites, and cysts of bradyzoites.
Toxoplasmosis
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ETIOLOGIC DIAGNOSIS The agent responsible for toxoplasmosis is Toxoplasma gondii. There are three infectious forms: • Sporulated oocysts (9–11 µm): characterized by having two sporocysts with four sporozoites each. They are the form with resistance to environmental conditions (Fig. 1). • Tachyzoites (2–4 × 4–7 µm): form of rapid multiplication. Tachyzoites develop and multiply intracellularly. • Bradyzoites are in cystic structures called pseudocysts: the slowly multiplying form. Young tissue cysts measuring 5 µm in diameter contain two bradyzoites, while older tissue cysts can hold hundreds of bradyzoites.
EPIDEMIOLOGY The cat is the definitive host and the most important in the life cycle. More common in warm and low-lying regions.
CLINICAL Most severe in transplacentally infected kittens. Adults with non-specific clinical signs.
Figure 1. Oocysts of Toxoplasma gondii (9–11 µm) (100x). Image courtesy of SALUVET Group (Faculty of Veterinary Medicine, Universidad Complutense de Madrid, Spain).
LABORATORY Identification by artificial sporulation in the laboratory or molecular techniques. Detection by mouse / cat bioassay or DNA amplification technique.
POST MORTEM Tissue necrosis in different locations.
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ATLAS OF PARASITOLOGICAL DIAGNOSIS IN DOGS AND CATS
ENDOPARASITES
EPIDEMIOLOGICAL DIAGNOSIS Toxoplasma gondii is a cosmopolitan protozoan that affects all warm-blooded animals. Only cats will eliminate oocysts with epidemiological consequences for pets and humans. The cat is the most important host in the life cycle of this parasite. In different recent studies, the seroprevalence in the feline population is highly variable: Australia 39–50 %; Belgium 70.2 %; Canada 12 %; Germany 45–65.6 %; Japan 5.4–47.1 %; Singapore 30.3 %; Sweden 42–46.6 %; USA 22–80 %. Overall, Toxoplasma gondii is considered a more common parasite in warm regions and low altitude in cold and mountainous regions. The prevalence is also higher in wet areas than dry areas. Kittens are those with the greatest epidemiological importance because they excrete oocysts after primary infection. Other major sources of oocysts are stray cats and cats on farms that have access to intermediate hosts, as well as access to the ingestion of fetal tissues from abortions or tissues of animals slaughtered on the farm.
CLINICAL DIAGNOSIS Both the cat and the dog may suffer from a clinical toxoplasmosis. Clinical signs are non-specific in adult animals. Clinical toxoplasmosis may be suspected in animals that mainly present with neurological disorders, uveitis (Fig. 2), lethargy and dyspnea from pneumonia. Other clinical signs described are chorioretinitis, fever, tachypnea, abdominal distension, vomiting, diarrhea, enlarged lymph nodes, jaundice, anorexia and weight loss. Toxoplasmosis is most severe in kittens infected transplacentally. Animals may be stillborn or die within a few hours of birth. Clinical signs observed in neonates are cough, anorexia, lethargy, hyperaesthesia, hypothermia and sudden death. Cats infected transplacentally or neonatally are more likely to develop uveitis.
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Figure 2. Uveitis in a cat with clinical toxoplasmosis. © G. Miró.
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PROTOZOOSES
Toxoplasmosis
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LABORATORY DIAGNOSIS In the cat, the oocysts with typical morphology (12 × 10 µm) can be detected in stool analysis using flotation methods. However, the likelihood of being detected in a cat is less than 1 %, because they are only shed for 1–2 weeks over the life of the animal and are often not present in the feces of cats on subsequent infections. For proper identification, it is necessary to cause the sporulation of the oocysts in the laboratory using Petri dishes with 2.5 % potassium dichromate for 1 week at 24 °C (Fig. 3) or by molecular techniques (PCR and sequencing) (Fig. 4) that allow their differentiation from oocysts of other coccidia of similar sizes (Hammondia hammondi and Besnoitia spp.). Toxoplasma gondii detection can be performed using samples from exudates, placenta, fetal adnexa, and remains of abortions, urine, feces, lymph nodes and bone marrow. The parasite can be shown to be present by mouse / cat bioassay after inoculation (intraperitoneally in mouse or orally in cats) with biological samples suspected of harboring cysts with bradyzoites, with the goal of detecting (30–45 days after inoculation) clinical toxoplasmosis in these experimentally infected animals (Fig. 5). DNA amplification technique by PCR can be used to detect tachyzoites in aqueous humor, milk, cerebrospinal fluid, and peripheral blood. Serological diagnosis is based on the detection of immunoglobulins (IgM or IgG). A prolonged IgM positivity can be associated with an active or reactivated chronic infection. Specific IgG will rise beginning 2–4 weeks after infection and persist for at least 1 year. However, a single positive IgG titer does not distinguish active infection from chronic infection. It is necessary to make at least two measurements of serum IgG within 2–3 weeks and, if they rise to four times the original titers, it can be considered an active infection (positive seroconversion) (Figs. 6 and 7).
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Figure 3. Sporulation of Toxoplasma gondii in the laboratory using Petri dishes with 2.5 % potassium dichromate. © G. Miró.
Figure 4. Toxoplasma gondii detection by PCR. © G. Miró.
Figure 5. Clinical toxoplasmosis in a laboratory mouse. © G. Miró.
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ATLAS OF PARASITOLOGICAL DIAGNOSIS IN DOGS AND CATS
Figure 6. Negative indirect immunofluorescence antibody (IFA) test result for toxoplasmosis. © G. Miró.
POST MORTEM FINDINGS
ENDOPARASITES
Figure 7. Positive indirect immunofluorescence antibody (IFA) test result for toxoplasmosis. © G. Miró.
20.0
µm
Affected animals show tissue necrosis due to the multiplication of tachyzoites. These lesions are located in the lung (Fig. 8), liver, mesenteric lymph nodes, pancreas, heart and brain. Lung lesions observed are nodular white-grayish foci of 5 mm in diameter, diffuse edema, and congestion. Neuronal lesions consist of necrosis, gliosis and vasculitis, characteristic of multifocal non-suppurative meningoencephalitis.
Figure 8. Lung aspirate from a fine needle pulmonary biopsy of a cat with clinical toxoplasmosis after continuous treatment with cyclosporine. Note the presence of free tachyzoites and aggregates of tachyzoites within a macrophage. Image courtesy of Prof. Sue Foster (Murdoch University, Perth, Western Australia).
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