Parasites by Host - Ruminants PDF

PARASITES BY HOST: RUMINANTS  BY THE END OF THIS PRESENTATION, YOU SHOULD BE ABLE TO: Provide a differential list of parasites that cause the clinical signs reported in the host Generate a diagnostic plan to rule in or out parasites on the differential list, and what the...

PARASITES BY HOST: RUMINANTS  BY THE END OF THIS PRESENTATION, YOU SHOULD BE ABLE TO: Provide a differential list of parasites that cause the clinical signs reported in the host Generate a diagnostic plan to rule in or out parasites on the differential list, and what the expected findings would be for each test Design a treatment plan depending on the parasite affecting the host Inform owners regarding methods of prevention of future infections by these parasites MY SHEEP HAS WOOL ISSUES Arthropods > Insecta > Diptera (flies) > Cyclorrhapha > Calliphoridae (blow flies) CALLIPHORIDAE (BLOW FLIES) Cause of wool strike in sheep Affects areas stained by urine or feces (perineum, prepuce), or areas wet from rain (flanks, withers, ventral neck) Toxins absorbed from myiasis can lead to death Treatment: Coumaphos spray or dip, cyromazine (insect growth regulator) Prevention: Clip wool around prepuce, tail docking Mules’ operation: Removal of redundant skin folds Arthropods > Arachnids > Acari > Astigmata > Psoroptidae > Psoroptes PSOROPTES Long legs, long pretarsi with three segments Psoroptes ovis: Causes scabies in cattle, sheep, and horses Intense pruritus with scabs, wool loss Reportable More prevalent in southwestern U.S. Pierces skin surface at base of hairs to feed on serum Treatment: Macrocyclic lactones, coumaphos MY CATTLE HAVE SKIN PARASITES Arthropods > Insecta > Phthiraptera (lice) > Anoplura (sucking lice) > Linognathus, Solenopotes LINOGNATHUS & SOLENOPOTES First pair of tarsal claws smaller than second and third pairs Linognathus vituli, Solenopotes capillatus: cattle Linognathus ovillus, L. pedalis, L. africanus: sheep Linognathus stenopsis, L. africanus: goats Arthropods > Insecta > Diptera (flies) > Cyclorrhapha > Oestridae (botflies) > Hypoderma HYPODERMA SPP. (HEELFLIES, GADFLIES) Hypoderma bovis and Hypoderma lineatum Adults oviposit on hairs of leg Larvae burrow through skin and migrate through body H. lineatum accumulate in esophagus H. bovis accumulate in spinal canal Third-stage larvae found in lumps on dorsum (warbles) Can aberrantly parasitize horses and humans Treatment: Ivermectin, doramectin, eprinomectin, moxidectin, organophosphates Arthropods > Arachnids > Acari > Ixodida (ticks) > Argasidae (soft ticks) > Otobius OTOBIUS Otobius megnini (Spinose ear tick) Covered in spines Larvae and nymphal stages in ear canals of cattle remain on host for up to 4 months Drop to ground to molt to adult stage Adults do not feed; they mate and female deposits one clutch of eggs in the soil Arthropods > Arachnids > Acari > Mesostigmata > Railletia RAILLETIA Railletia auris: Mite in ear of cattle Associated with ulceration, blockage of auditory canal, hearing loss, circling, ataxia, unilateral facial paralysis Treatment: Flumethrin applied to ear canal Arthropods > Arachnids > Acari > Astigmata > Psoroptidae > Chorioptes CHORIOPTES Chorioptes bovis: Short pretarsi with unsegmented pedicels Males have turret-like lobes on posterior margin of body Commonly distributed on tail, escutcheon, and legs of cattle Typically occur in the late winter as mild pruritus Treatment: Macrocyclic lactones, coumaphos MY SHEEP HAS DIARRHEA Nematoda > Secernentea > Strongylida (bursates) > Trichostrongylida (threadworms) > Trichostrongylus TRICHOSTRONGYLUS Small worms, very reduced buccal cavity Short, twisted, pointed spicules Infective third-stage larvae survive winter on pasture, ingested in spring Typically asymptomatic, but high numbers can cause diarrhea in sheep, goats, and cattle Feces on fleece can attract blowflies, leading to myiasis Trichostrongylus axei: Stomach or abomasum of horses and ruminants Protists > SAR > Apicomplexa > Coccidians > Eimeria EIMERIA Sheep and goats: Clinical signs common in sheep after shipping Goats much more susceptible to disease Commonly cause diarrhea in kids older than 2 weeks Can perform direct fecal smear for merozoite detection if prepatent infection is suspected Treatment: Decoquinate, lasalocid, sulfaquinoxaline, monensin Off-label amprolium MY CATTLE HAVE DIARRHEA  ACTIVE LEARNING ACTIVITY List some causes of diarrhea in cattle, and what tests you could run to rule in or out your differentials. Nematoda > Secernentea > Strongylida (bursates) > Trichostrongylida (threadworms) > Ostertagia,Teladorsagia OSTERTAGIA/TELADORSAGIA Related species: Teladorsagia in sheep and goats, Ostertagia in cattle Live as adults in abomasum of ruminants Third-stage larvae survive winter on pasture, ingested in spring Clinical signs: diarrhea, anemia, hypoproteinemia, emaciation Typically in young calves “Moroccan leather” appearance of abomasal mucosa on necropsy Protists > SAR > Apicomplexa > Gregarines > Cryptosporidium CRYPTOSPORIDIUM Transmitted through oocysts (immediately infective when passed) Oocysts can excyst before leaving host, leading to autoinfection Cryptosporidium parvum: Calves younger than 30 days Also in sheep, goats, and horses Cryptosporidium ryanae: Calves up to 1 year of age Cryptosporidium bovis: Adult cows Can develop diarrhea in cattle, usually due to C. parvum Can develop mild diarrhea with C. andersoni Protists > SAR > Apicomplexa > Gregarines > Cryptosporidium CRYPTOSPORIDIUM Diagnosis: Colorless, transparent, and small oocysts (4-8um) on fecal flotations Concentration sucrose best flotation solution Oocyst walls appear with pinkish hue Treatment: No specific effective treatment licensed in U.S. Protists > SAR > Apicomplexa > Coccidians > Eimeria EIMERIA Cattle: Very common in young calves Finding oocysts in diarrheic feces does not necessarily mean coccidiosis Most pathogenic species are Eimeria zuernii or E. bovis, can cause diarrhea with bloody stool and tenesmus Winter coccidiosis: Seen in calves during winter, when cold weather precipitates clinical disease Nervous coccidiosis: Can develop in up to 1/3 of infected animals Protists > SAR > Apicomplexa > Coccidians > Eimeria EIMERIA Cattle: Diagnosis: Eimeria oocysts on fecal flotation Treatment: Amprolium, monensin, sulfamethazine, sulfadimethoxine, sulfaquinoxaline Often not very helpful by the time oocysts are noted Prevention: Amprolium, decoquinate, lasalocid, monensin Avoid monensin in horses Platyhelminths > Trematodes > Paramphistomum PARAMPHISTOMUM CERVI Adults have ventral sucker at posterior end of body (acetabulum) Live in rumen of cattle, sheep, and goats Ingested metacercariae excyst in small intestine, migrate through abomasum back to rumen Migration can cause prolonged disease Diarrhea, depression, anorexia Treatment: No labeled treatments in U.S. Nematoda > Secernetea > Rhabditida > Strongyloides STRONGYLOIDES Tiny parthenogenic female nematodes Lives in mucosal crypts of small intestine Strongyloides papillosus: ruminants Disease: Ruminants can develop diarrhea, nervous signs, and cardiac lesions with sudden death Lead to precocious udder development Diagnosis: Eggs containing rhabditiform larvae in feces Treatment: Macrocyclic lactones, benzimidazoles MY SHEEP ARE SNEEZING Arthropods > Insecta > Diptera (flies) > Cyclorrhapha > Oestridae (botflies) > Oestrus OESTRUS OVIS Sheep nasal botfly Stout, grayish-brown adults, covered with short hairs Active in bright sun Females deposit larvae in sheep nostrils Larvae develop in mucosa of nasal cavity then frontal sinus, sneezed out and pupate Heavy infection causes sneezing and nasal discharge Treatment: ivermectin, eprinomectin MY SHEEP IS COUGHING Nematoda > Secernetea > Strongylida (bursates) > Metastrongyloidea (lungworms) > Muellerius MUELLERIUS Small worm with well developed bursa Lives as adults in the lung of sheep and goats Sheep and goats infected by ingesting L3 in snails and slugs Diagnosis: Baermann technique for L1 in feces Disease: Usually nonpathogenic Can cause chronic pneumonia Treatment: Moxidectin, eprinomectin MY CATTLE ARE COUGHING Nematoda > Secernentea > Strongylida (bursates) > Trichostrongylida (threadworms) > Dictyocaulus DICTYOC AULUS Long, white worms with small buccal cavity Short, granular spicules, reduced bursa Live as adults in the respiratory tract of ruminants and horses, first-stage larvae passed in eggs often hatch before passing into feces Dictyocaulus viviparus: Cattle Dictyocaulus filaria: Sheep Disease: Chronic bronchitis, bronchial tree occlusion, atelectasis Diagnosis: First stage larvae in feces detected via Baermann method Treatment: Macrocyclic lactones, benzimidazoles MY CATTLE ARE ABORTING Protists > Excavata (flagellates) > Trichomonadida > Tritrichomonas TRITRICHOMONAS FOETUS Worldwide distribution Found in reproductive tract of male and female cattle, and macerated fetuses Transmission during copulation Results in infertility, abortion, fetal mummification, and pyometra Often fetal loss in early gestation and return to estrus Infection not evident in males Infected cows will have organisms in vaginal secretions first 2-3 weeks after copulation Treatment: None available currently Protists > SAR > Apicomplexa > Coccidians > Neospora NEOSPORA C ANINUM Cattle intermediate hosts infected by ingesting oocysts in environment (passed from canine feces) Major cause of bovine abortion in dairy cattle Sheep, goats, and camelids can also abort Calves can be born congenitally infected, become persistently carriers Diagnosis: Serology and PCR aid in diagnosis Treatment: No approved treatment in cattle or dogs Protists > SAR > Apicomplexa > Coccidians > Besnoitia BESNOITIA Form large cysts with bradyzoites in skin, sclera, and tissues of intermediate hosts Life cycle uncertain Final host usually is a cat Transmission may be via direct contact with ruptured cysts or mechanical insect vectors Besnoitia besnoiti: Cattle Can cause fever, weight loss, decreased milk production, abortion, death rarely Treatment: No effective treatment reported, selective culling recommended Protists > SAR > Apicomplexa > Aconoidasida > Piroplasmorida > Theileria THEILERIA IN CATTLE Theileria orientalis: Transmission via Haemaphysalis longicornis in U.S. Parasites multiply mostly in RBCs Causes anemia, jaundice, weakness, abortion Pregnant heifers and calves particularly susceptible Cattle that recover become carriers Reported in 2017 in Virginia, with 28 cases in Virginia and West Virginia since then Diagnosis: Blood smear, lymph node aspirate, serology, PCR Treatment: Currently no approved treatments PRACTICE QUESTIONS