Veterinary Parasitology Arthropod Parasites

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1 Veterinary Parasitology Arthropod Parasites Melanie Buote DVM, DACVP, PhD Candidate Office: 3319 North Annex, Office phone #(902) Cell phone #(902)

2 A little about me BSc, Hon Marine Bio DVM Anatomic Pathology Residency Diagnostic Pathologist PhD Met Husband Got Married Had Babies

3 Bitter Crab Disease

4 Bitter Crab Disease Hematodinium sp. infection: A dinoflagellate (protozoan) parasite of decapod crustacean (arthropod) hemolymph

Outline I. Protozoan parasites transmitted by arthropods (1 lecture) 1. Hemoflagellates Trypanosomes and Leishmania 2. Piroplasms Babesia and Cytauxzoon 3.

5 Outline I. Protozoan parasites transmitted by arthropods (1 lecture) 1. Hemoflagellates Trypanosomes and Leishmania 2. Piroplasms Babesia and Cytauxzoon 3. Malarias Plasmodium and Leucocytozoon II. Arthropods (6 lectures) 1. Arachnids (3 lectures) Ticks and mites 2. Insects (3 lectures) Fleas, lice, flies, and myiasis 3. Crustaceans (0 lectures) Sea lice

Biological Vector Parasite undergoes development within arthropod vector Arthropod can be an

6 Protozoan parasites transmitted by arthropods 1. Mechanical Vector Carried by mouthparts/body e.g. Horse flies (Tabanus) transmit Equine Infectious Anemia on their mouthparts 2. Biological Vector Parasite undergoes development within arthropod vector Arthropod can be an intermediate host or the definitive host e.g. Plasmodium undergo sexual reproduction in the Anopholene mosquito (definitive host)

7 Protozoan parasites transmitted by arthropods Hemoflagellates Trypanosoma Piroplasms Babesia Malarias Plasmodium Leishmania Cytauxzoon Leucocytozoon

8 Protozoan parasites transmitted by arthropods I. Hemoflagellates Genera of veterinary importance: 1. Trypanosoma 2. Leishmania Morphology Elongate with a single flagellum or Rounded with a non-protruding flagellum All possess a kinetoplast Sausage or disc-shaped Found at base of flagellum Contains mitochondrial DNA

9 Stage in arthropod intestine Hemoflagellate Life Cycles Stage in vertebrate blood and/or tissues Chagas Disease Zoonotic disease caused by Trypanosoma cruzi

10 I. Hemoflagellates 1. Trypanosomes Section Salivaria Section Stercoraria* Development in front portion of digestive tract of the arthropod Transmission to vertebrate host via saliva African Trypanosomiasis -Trypanosoma congolense -Trypanosoma vivax -Trypanosoma brucei brucei Development in hind portion of digestive tract of the arthropod Transmission to vertebrate host via feces American Trypanosomiasis -Trypanosoma cruzi *Stercorary = dung repository

11 I. Hemoflagellates, 1. Trypanosomes i. African Trypanosomiasis Major species Trypanosoma congolense Cattle, sheep, goats, dogs, pigs, camels, horses, most wild animals Trypanosoma vivax Cattle, sheep, goats, camels, horses, various wild animals Trypanosoma brucei brucei All domestic and various wild animals Most severe in dogs, horses, cats Trypanosoma simiae Domestic and wild pigs, camels Transmission: Tsetse fly (Glossina spp.) (FYI: T. vivax can also be transmitted by biting flies in non-tsetse areas = mechanical transmission)

Animals can also host human pathogen parasites Domestic and wild animals = parasite reservoirs T. brucei rhodesiense > T. b. gambiense I. Hemoflagellates, 1. Trypanosomes i.

12 Animals can also host human pathogen parasites Domestic and wild animals = parasite reservoirs T. brucei rhodesiense > T. b. gambiense I. Hemoflagellates, 1. Trypanosomes i. African Trypanosomiasis Bovine trypanosomiasis (Nagana) Sudden death in cattle (T. vivax) Due to secondary infections (i.e., Salmonellosis) Chronic disease in cattle: Anemia, cachexia, chronic ill health, abortion, reduced productivity ~3 million cattle deaths/year Loss in cattle & crop production Nagana many domestic species are susceptible Cattle, equidae, small ruminants, camels, and dogs Horses, dogs - Incoordination and spinal paralysis Dogs - Anterior uveitis (perivascular infections)

reservoirs Skunks, cats, pigs, raccoons, opossums, armadillos Cause:

transfusions Distribution Endemic in South and Central America Low prevalence

13 I. Hemoflagellates, 1. Trypanosomes ii. American Trypanosomiasis Chagas Disease Dogs and Humans (zoonotic) Animal reservoirs Skunks, cats, pigs, raccoons, opossums, armadillos Cause: Trypanosoma cruzi Transmission: Triatomine bug ( Kissing bug ) Blood transfusions Distribution Endemic in South and Central America Low prevalence in USA (sporadic cases) Southern US States + Virginia/Maryland Potential for expansion of distribution Where there are Triatomine bugs

14 I. Hemoflagellates, 1. Trypanosomes ii. American Trypanosomiasis Two forms of Chagas Disease in dogs: 1. Acute disease (usually young dogs <2 years old) Lymphadenopathy, pale mucus membranes, lethargy, hepatosplenomegaly, myocarditis, and tachyarrhythmia 2. Chronic disease Congestive heart failure Heart becomes enlarged and flabby After extended asymptomatic period Pathogenesis: Multiplying amastigotes host cell destruction local inflammatory response host cell degeneration and necrosis more inflammation Preference for cardiac and skeletal muscle cells

pointed posterior end Found in circulating blood of the vertebrate host

undulating membrane Amastigote Spheroid, 1.5-4.

vertebrate host Epimastigote Kinetoplast located between the nucleus and the

15 I. Hemoflagellates, 1. Trypanosomes ii. American Trypanosomiasis Morphology Trypomastigote Slender, um long with a pointed posterior end Found in circulating blood of the vertebrate host Kinetoplast is near the posterior end Flagellum is long & anterior Narrow undulating membrane Amastigote Spheroid, um, lack flagella Develop in clusters Found in muscle and other tissues of vertebrate host Epimastigote Kinetoplast located between the nucleus and the anterior end near the flagellum Found in the posterior portion of a triatomine bug s gut Helpful hints for remembering terms: Trypano = borer or screw-like, A = not, Mastigote = flagellate

16 I. Hemoflagellates, 1. Trypanosomes ii. American Trypanosomiasis (Chagas Disease)

17 I. Hemoflagellates, 1. Trypanosomes ii. American Trypanosomiasis(Chagas Disease) Diagnosis Acute infections Detection of trypomastigotes in blood smear or lymph Within 5 weeks of infection Chronic infections: Culture, Serology (IFA) Xenodiagnosis Naive triatomine bugs feed on host Look for parasites in bug s gut Necropsy with histology Clusters of amastigotes in skeletal and cardiac muscles

18 I. Hemoflagellates, 1. Trypanosomes ii. American Trypanosomiasis (Chagas Disease) Treatment & Control Does not respond well to treatment Only extracellular parasites (trypomastigotes) killed Intracellular stages (amastigotes) unaffected by treatment disease recrudescence Symptomatic treatment Medical management of CHF Prevention Insecticides Limit & control exposure to arthropod vectors Avoid contact with reservoir animals Skunks, raccoons, opossums, armadillos Avoid sleeping in a mud, thatch or adobe house. Types of residences more likely to harbor triatomine bugs

19 Protozoan parasites transmitted by arthropods Hemoflagellates Trypanosoma Piroplasms Babesia Malarias Plasmodium Leishmania Cytauxzoon Leucocytozoon

20 Protozoan parasites transmitted by arthropods Hemoflagellates Trypanosoma Leishmania I. Hemoflagellates 1. Trypanosomes i. African Trypanosomiasis ii. American Trypanosomiasis (Chagas Disease) 2. Leishmania

21 I. Hemoflagellates 2. Leishmania (Leishmaniasis) Hosts Dogs and Humans (zoonotic) Rodents, wild mammals, rare in cats Horses, mules, donkeys Cause: Leishmania donovani species complex Transmission: Female sandflies Phlebotomus sandflies (Eastern Hemisphere) Lutzomyia sandflies (Western Hemisphere ) Blood transfusion +/- vertical and horizontal transmission

22 I. Hemoflagellates 2. Leishmania Distribution: Endemic in the tropics: Mediterranean, Middle East, Asia, Central + South America Sporadic reports in North America: English & American Foxhounds in USA, Southern Ontario, & Nova Scotia

many organisms in lesions), Often affects the head/face and limbs, +/- chronic ulcers, +/- nail deformites, secondary infections

23 I. Hemoflagellates 2. Leishmania Clinical forms of leishmaniasis 1. Cutaneous leishmaniasis Non-specific skin lesions Alopecic or nodular forms (few vs. many organisms in lesions), Often affects the head/face and limbs, +/- chronic ulcers, +/- nail deformites, secondary infections common +/- systemic infection 2. Visceral leishmaniasis Non-specific systemic signs Poor body condition, rough hair coat, chronic wasting, recurrent oculonasal discharge, recurrent diarrhea, mildly enlarged lymph nodes, hepatosplenomegaly with granulomas

24 I. Hemoflagellates 2. Leishmania Pathogenesis Leishmania organisms are engulfed by macrophages multiply rapidly (binary fission) and destroy the macrophage engulfed by more macrophages formation of granulomas in skin and organs Destruction of cells (i.e., macrophages) from the reticuloendothelial system susceptibility to secondary pathogens

25 I. Hemoflagellates 2. Leishmania

I. Hemoflagellates 2. Leishmania Morphology Amastigote Spheroid, lack flagella, 2.5-5.

26 I. Hemoflagellates 2. Leishmania Morphology Amastigote Spheroid, lack flagella, um Found in the vertebrate hosts tissue Often found within macrophages Kinetoplast is oriented perpendicular to nucleus (lollipop) Promastigote found in the gut of the sandfly vector forward extending flagellum kinetoplast is located near the anterior end of the body Helpful hints for remembering terms: A = not; Pro = before, earlier, or in favor of; Mastigote = flagellate

nodes, skin nodules) or bone marrow aspirates Amastigotes within macrophages or free (ruptured host cells) BUT

27 I. Hemoflagellates 2. Leishmania Diagnosis Fine needle aspirates (FNAs) of enlarged organs and/or granulomas (liver, spleen, lymph nodes, skin nodules) or bone marrow aspirates Amastigotes within macrophages or free (ruptured host cells) BUT beware of false negative FNAs! Biopsy with histopathology Detect antibodies to parasite in serum Immunofluorescent Antibody test (IFA) Enzyme-Linked Immunosorbent Assay (ELISA) Q-PCR for detection of parasite

28 I. Hemoflagellates 2. Leishmania Treatment and Control Symptomatic medical treatment to reduce the clinical signs of disease (not curative) Meglumine Antimoniate with Allopurinol, Aminosidine & Amphotericin B All drugs require multiple dose regimens Depend on the patient's condition & owner cooperation Relapse is common Weeks, months or years later Vector control is essential Use of insecticide collars, shampoos or sprays Especially in patients under treatment Residual insecticide spraying of houses & animal shelters may help

29 Protozoan parasites transmitted by arthropods Hemoflagellates Trypanosoma Piroplasms Babesia Malarias Plasmodium Leishmania Cytauxzoon Leucocytozoon

30 Protozoan parasites transmitted by I. Hemoflagellates 1. Trypanosomes arthropods i. African Trypanosomiasis and Nagana ii. American Trypanosomiasis (Chagas Disease) 2. Leishmania i. Leishmaniasis II. Piroplasms 1. Babesia 2. Cytauxzoon 3. Theileria

31 II. Piroplasms Piriform (pear-shaped) intracellular apicomplexan parasites Parasites of blood cells in vertebrates Transmitted by ixodid (hard) tick vectors

32 II. Piroplasms Morphology 1. Babesia spp. Merozoites are found in the erythrocytes of the vertebrate host Piriform to amoeboid 3-5 µm long and 2-4 µm in diameter Size is species dependent Blue cytoplasm with red chromatin mass (Wright-Geimsa) 2. Cytauxzoon felis Signet-ring like merozoites found in erythrocytes µm in diameter Merozoites may be found within monocytes/macrophages (histiocytes) in spleen, lymph nodes, lungs, liver and kidneys

33 Piroplasmosis Human Babesiosis 1. Babesia spp. Schizogony in erythrocytes 2. Cytauxzoon sp. Schizogony in erythrocytes and histiocytes (macrophages) 3. Theileria spp. Schizogony in lymphocytes (+/- macrophages) Schizogony = Merogony (asexual reproduction via fission giving rise to merozoites)

34 II. Piroplasms Pathogenesis 1. Babesia spp. Destruction of parasitized erythrocytes hemolytic anemia lethargy, inappetance, jaundice, dehydration, dark urine Clogging of capillaries in various organs by parasitized cells & free parasites anoxia, accumulation of toxic metabolites, hemorrhaging & organ failure Most characteristic feature of B. bovis infections is a cerebral flush (diffuse reddening of gray matter of brain due to capillary congestion) 2. Cytauxzoon sp. Destruction of parasitized erythrocytes hemolytic anemia lethargy, inappetance, jaundice, dehydration, dark urine Infected histiocytes (macrophages) can clog venules in organs and infiltrate tissues (liver, spleen, lungs, lymph nodes, bone marrow) hepatosplenomegaly, lymphadenomegaly +/- liver enzymes & prolonged clotting times Pancytopenia can be seen ( RBCs, WBCs, platelets)

as parasites are more common & numerous in capillary blood 2.

35 II. Piroplasms Diagnosis 1. Babesia spp. History, clinical signs, serology Observation of merozoites within erythrocytes on stained blood smears Collected blood from ear, tip of the tail, or toe nail as parasites are more common & numerous in capillary blood 2. Cytauxzoon felis History & clinical signs Observation of merozoites within erythrocytes on stained blood smears Intraerythrocytic parasites need to be differentiated from Babesia felis and Mycoplasma haemofelis Observation of merozoites in histiocytes (macrophages) in tissue impression smear (cytology) or histology (biopsies or necropsies) Intrahistiocytic stages = diagnostic

36 II. Piroplasms Treatment & Control 1. Babesia Diaminazene I.M. or phenamide S.C. 2. Cytauxzoon Rapidly fatal disease No treatment has proven effective Prevention Tick control Ticks are rarely seen on cats (grooming behavior)

37 Piroplasmosis Ixodid Tick Vectors (FYI) Disease Causative agent Ixodid Tick Vector Bovine Babesiosis ( Red Water Fever ) Bovine Babesiosis ( Red Water Fever ) Bovine Theleiriosis ( East Coast Fever ) Babesia bigemina Babesia bovis Babesia divergens Babesia argentina Theileria parva Rhipicephalus (Boophilus) annulatus (eradicated) Rhipicephalus (Boophilus) microplus Rhipicephalus appendiculatus Canine Babesiosis Babesia gibsonii Rhipicephalus sanguinensis (brown dog tick) Feline Cytauxzoonosis Equine Babesiosis Human Babesiosis (Zoonosis) Cytauxzoon felis (bobcat wildlife reservoir) Babesia caballi Theileria (Babesia) equi Babesia microti (parasite of voles and mice) Dermacentor variablis (presumed) Genera: Dermacentor, Hyalomma, and Rhipicephalus Ixodes scapularis

38 Protozoan parasites transmitted by arthropods Hemoflagellates Trypanosoma Piroplasms Babesia Malarias Plasmodium Leishmania Cytauxzoon Leucocytozoon

39 Protozoan parasites transmitted by arthropods I. Hemoflagellates 1. Trypanosomes i. African Trypanosomiasis and Nagana ii. American Trypanosomiasis (Chagas Disease) 2. Leishmania i. Leishmaniasis II. III. Piroplasms 1. Babesia 2. Cytauxzoon 3. Theileria Malarias 1. Plasmodium 2. Leukocytozoon 3. Haemoproteus

Parasites of domestic & wild birds Over 60 species known to infect birds Transmitted by the

40 III. Malarias 1. Plasmodium spp. Avian Malaria and Human Malaria Transmitted by mosquitoes 2. Leucocytozoon spp. Parasites of domestic & wild birds Over 60 species known to infect birds Transmitted by the black fly, Simlulium spp. 3. Haemoproteus spp. Birds and reptiles Usually an incidental finding (i.e., non-pathogenic) Transmitted by louse flies & biting midges

Malaria Avian Malaria Transmission Mammals - anopheline mosquito

) Human malaria Between 100-300 million people are infected/year

41 III. Malarias 1. Plasmodium spp. Humans & non-human primates, rodents, birds & reptiles Human Malaria Avian Malaria Transmission Mammals - anopheline mosquito (Anopheles spp.) Birds - culicine mosquito (Culex spp.) Human malaria Between million people are infected/year ~1 million people die from malaria each year 90% of deaths due to Plasmodium falciparum P. knowlesi in macaques = zoonotic

42 FYI: Female mosquitoes use two volatile cues to select and navigate toward hosts: 1. Exhaled CO2 2. Skin odorants Female mosquitoes detect plumes of exhaled CO2 using a class of olfactory receptor neurons (ORNs) designated cpa. CpA neurons are housed in capitate peg (cp) sensilla on the maxillary palps and express the CO2 receptor, comprising three conserved members of the Gustatory receptor gene family

43 Avian Malaria Numerous species of genus Plasmodium Plasmodium relictum Transmission To birds by culicine mosquito (i.e., Culex spp.) Clinical signs Anemia, lethargy, hepatomegaly, and hepatitis Can be fatal in non-adapted species Penguins (animals in captivity) Hawaiian forest birds Hawaiian crows, honeycreepers (apapane < i iwi)

44 III. Malarias 2. Leucocytozoon spp. Transmitted by the black fly Simulium spp. Parasites of birds Domestic & wild Over 60 species L. simondi Infects ducks & geese (Canadian geese) L. caulleryi Infects chickens L. smithi Infects turkeys

45 III. Malarias 2. Leucocytozoon 1. Black fly transmits sporozoites to vertebrate host Sporozoites disseminate and infect a variety of cell types and undergo shizogony (esp. in liver) cell lysis merozoites released 2. Merozoites infect RBCs, WBCs, and endothelial cells gametocytes Merozoites in RBCs ROUND gametocytes Merozoites in endothelial cells megaloschizonts merozoites invade WBCs ELONGATE gametocytes 3. Gametocytes ingested by black fly sporogony in gut & salivary glands

46 III. Malarias, 2. Leucocytozoon Pathogenesis Destruction (lysis) of infected host cells Ruptured schizonts may induce granulomatous reactions in the surrounding tissues Results in anemia, leukocytosis, splenomegaly, & hepatomegaly Megaloschizonts appear as grey-white nodules Found in the heart, liver, lung or spleen. Megaloszhizonts in endothelial cells occlusion of blood vessels ischemic necrosis and associated inflammation in the heart, brain, spleen, and liver Livers are variably enlarged and pale, may contain nodules (megaloschizonts +/- granulomas), and often contain areas of hemorrhage

47 III. Malarias 2. Leucocytozoon Clinical signs Majority of birds affected with leukocytozoonosis exhibit no signs. Young birds (most susceptible) Acute onset of anorexia, listlessness, laboured breathing, anemia (pallor), diarrhea (with green droppings) Susceptibility to secondary infections is increased. Significant death loss within 24 hours of clinical signs Typically signs appear days post exposure Older birds Chronic infections with low mortality, but can become listless & thin egg production, egg weight & hatchability Recovered birds harbour the parasite in their blood for over a year & often for life

48 III. Malarias 2. Leucocytozoon Diagnosis Blood smears Microscopic observation of gametocytes in stained thin blood smears Round & elongate gametocytes! Necropsy with histology Identification of schizonts and megaloschizonts in tissue sections New PCR test (research only)

49 III. Malarias, 2. Leucocytozoon Treatment & Control Preventive medication is the norm Sulfadimethoxine & pyrimethamine combinations Clopidol has been approved by the FDA for control of infections in turkeys Prevention Control black fly vector Keep domestic birds separated from wild birds (wildife reservoirs) Simulium black fly

50 Protozoan parasites transmitted by arthropods Hemoflagellates Trypanosoma Piroplasms Babesia Malarias Plasmodium Leishmania Cytauxzoon Leucocytozoon

51 Protozoan parasites transmitted by arthropods Hemoflagellates Trypanosoma Piroplasms Babesia Malarias Plasmodium Trypomastigotes in blood Merozoites in RBCs Merozoites in RBCs Leishmania Cytauxzoon Leucocytozoon Amastigotes in macrophages Merozoites in RBCs (& mø) Merozoites in RBCs, round & elongate gametocytes in blood

52 Protozoan parasites transmitted by 1. Hemoflagellates 1. Trypanosomes arthropods i. African Trypanosomiasis and Nagana (Tsetse fly) ii. American Trypanosomiasis (Chagas Disease; Triatomine kissing bug) 2. Leishmania i. Leishmaniasis (Sandflies) 2. Piroplasms 1. Babesia (Ixodid ticks) 2. Cytauxzoon (Ixodid ticks) 3. Malarias 1. Plasmodium (Mosquitoes) 2. Leukocytozoon (Black flies)

53 Protozoan parasites transmitted by arthropods Protozoan Vector Host Disease Trypanosoma congolense, T. vivax, T. brucei brucei Tse tse fly (Glossina sp.) African cattle (etc.) Bovine trypanosomiasis (Nagana) Trypanosoma cruzi Triatomine (kissing) bug (Triatoma sp.) Dogs Chagas Disease Leishmania donovani complex Phlebotomus sandfly Lutzomyia sandfly Dogs Leishmaniasis Babesia bovis Ixodid tick (Rhipicephalus appendiculatus) Cattle Bovine babesiosis Babesia gibsonii Ixodid tick (Rhipicephalus sanguinensis) Dogs Canine babesiosis Cytauxzoon felis Ixodid tick (Dermacentor variabilis) Cats (bobcats) Cytauxzoonosis Plasmodium relictum Culicine mosquito (Culex spp.) Birds Avian malaria Leucocytozoon simondi Simulium black fly (Simulium spp.) Ducks & geese & Chickens & Turkeys Leucocytozoonosis

Parasitic Protozoa, Helminths, and Arthropod Vectors

PowerPoint Lecture Slides for MICROBIOLOGY ROBERT W. BAUMAN Chapter 23 Parasitic Protozoa, Helminths, and Arthropod Vectors Parasitic Diseases Protozoan and helminthic parasites are emerging as serious