Apicomplexans II
Protozoan Parasites: Lecture 19 - Coccidia Part II & Cryptosporidium Pages 29-38 Coccidia: Life cycle & treatment effectiveness? Asexual stages Sexual stages Prophylactic drugs Current drugs only work on asexual stages outside of host cells Sanitation : within 24-48 hours i.e. before oocysts are mature & infective (sporulated oocyst) Supportive therapy - No current drugs kill/target sexual stages in cells Avian Coccidiosis Chickens - 9 species of Eimeria • Eimeria acervulina – – – – Most common Mildly pathogenic Upper small intestine Prepatent period: 4-5 days • Eimeria tenella – Most pathogenic (high mortality) – Cecum – Prepatent period: 7+ days Pathogenesis • Site of infection • Small intestine to cecum depending on species involved • Intestinal / cecal lesions range from minor to round, white/grey plaques to severe necrotic cores & hemorrhage with significant blood loss Clinical signs • Bloody droppings & hemorrhagic diarrhea beginning 4 days post infection • Acute death – High mortality rates • Emaciation, pallor & inappetence Control &Treatment • $ 700 million/year loss • Isolate sick birds - treating sick birds is futile • Treat healthy birds with anti-coccidial medications • Preventative (prophylactic) medication in feed – Ionophores (monensin, salinomycin, lasalocid) – Amprolium – Decoquinate... • Resistance is widespread – Rotate drugs or use "shuttle" program Control &Treatment • Vaccines have been developed but problems with administration – Injectable – Nebulizer/sprayer – Feed additive • Raise young chickens separate from older birds (segregation of industry) • Proper hygiene/sanitation Avian Coccidiosis • Turkeys – 7 species of Eimeria infect turkeys – E. adenoeides, E. gallopavonis, E. meleagrimittis are all pathogenic – Lesions < than in chickens, but mortality rates high in young birds • Ducks & Geese – Renal coccidiosis - Eimeria truncata – Intestinal coccidiosis - E. anseris Bovine Coccidiosis 13 species infect cattle in North America • Eimeria zuernii & Eimeria bovis – Most pathogenic – Mixed infections are the rule • Calves – Most susceptible – 3 weeks to 6 months of age, • Typically 2 - 6 months – Also older calves housed in groups • First generation meronts (first asexual replication stage) grow to giant size & produce thousands of merozoites – E. bovis - endothelial cells of lacteals in the villi – E. zuernii - lamina propria of the ileum • Prepatent period: 12-24 days Bovine Coccidiosis Clinical signs • Moderate infections: – Diarrhea, listlessness, anorexia Clinical signs • Severe infections: – Explosive liquid bloody diarrhea, emaciation & tenesmus – Hind quarters of calf can become soiled with feces – Secondary infections common • Pneumonia… – Calves that don’t die in 710 days will usually recover Eimeria bovis Summer Coccidiosis • Calves 3-6 months – Stress - first time on pasture – Older cows carriers & infect the pasture – Warm temperatures & high humidity – Diarrhea to dysentery – Tenesmus & projectile feces • Dehydration & death if untreated Eimeria zuernii Winter coccidiosis • Diarrhea & tenesmus • Severe cold weather • Stress factors – Weaning, shift from pasture to feedlot Eimeria zuernii Nervous coccidiosis • Acute diarrhea • Muscular tremors, convulsions, blindness • 50% mortality – Pathogenesis is not understood but majority of cases occur during coldest months (stress?) Control & Treatment • General prevention: – Reduce stocking rates, minimize stress, clean housing & feed – Pasture management? – Provide adequate colostrum • Treatment & prevention?: – Decoquinate, amprolium, monensin, sulfamethazine, sulfaquinoxaline, lasalocid Control & Treatment • Outbreak: • Sick calves – Isolate & provide supportive therapy & fluid replacement • Healthy calves – No clinical signs = treat with anti-coccidial drugs • Clean & sanitize – Housing between groups of calves – Hot & dry = kills oocysts • Do not mix calves of different ages • Reduce stress Ovine Coccidiosis 12 species of Eimeria infect sheep prepatent period ~ 14 days • Lambs in feedlot or after shipping – 12-21 days after arrival – Watery diarrhea for several days-2 weeks – Depression, inappetence followed by weight loss – Mortality usually <10%, • But significant weight loss can occur – Soiled wool leads to Fly strike (myiasis) Caprine Coccidiosis 6 species of Eimeria infect goats prepatent period ~ 14 days • More susceptible than sheep • Clinical signs of diarrhea typically follow weaning • Heavily infected – Usually die – Recovered kids may fail to grow normally Ovine / Caprine Coccidiosis • Control & Treatment – As in cattle – Raise lambs on slatted floor pens – Good sanitation Equine Coccidiosis • Eimeria leuckarti • Coccidiosis is rare in horses – Few reports of diarrhea or weight loss in infected horses micropyle = exit pore Oocyst with prominent micropyle Rabbit Coccidiosis • Eimeria stiedae • Liver – Bile duct epithelium – Biliary hyperplasia & cirrhosis resulting in diarrhea – Often subclinical – Young rabbits most susceptible – Anorexia, weight loss, distended abdomen, icterus & rough hair coat – Sudden death - infrequent Rabbit Coccidiosis • Eimeria intestinalis & – Crypts of small intestine • Eimeria flavescens – Cecum • Often subclinical • Anorexia, weight loss, & rough hair coat • Denuding of the epithelium & severe diarrhea • Death Control & Treatment • Prophylactic administration of sulfonamides or lasalocid • Reduce stress – Intestinal form occurs even in well cared for bunnies • Prevent contamination of feeders, waterers, cages, hutches... • Proper management Swine Coccidiosis • Isospora suis – Severe disease in nursing piglets – Post 1960's – Wherever pigs are farrowed in confinement – 15-20% of piglet diarrhea Swine Coccidiosis • Isospora suis – Enterocytes of the small intestine & occasionally cecum & colon – Prepatent period 4-5 days – Patent period 2 weeks Clinical signs • Piglets 1-2 weeks – Yellow- grey pasty diarrhea • Diarrhea smells like "soured milk“ • Blood not present unless other disease agents involved – e.g. rotavirus • Depressed weight gains, high morbidity, moderate mortality Clinical signs • Piglets 5-6 weeks – Post-weaning diarrhea • Depressed weight gains, high morbidity, moderate mortality Control & Treatment • Anti-coccidials are not effective • Nursing piglets do not eat or drink enough for drugs added to feed or water to be effective • Sanitation to reduce the number of infectious oocysts in environment • Reduce stress Canine Coccidiosis • Isospora canis • Largest oocysts in dogs • Lamina propria of distal small intestine & may cause diarrhea associated with weaning stress – Concurrent bacterial or viral infections? Canine Coccidiosis • Isospora ohioensis complex • I. ohioensis, I. burrowsi & I. neorivolta – All have small oocysts – Enterocytes in the small intestine, cecum & colon – Diarrhea in puppies is: • Associated with stress • Concurrent bacterial or viral infections? Feline Coccidiosis • Isospora felis & Isospora revolta • Develop in the enterocytes of small intestine & can cause diarrhea & enteritis in kittens • Newborn - 4 weeks old • Stress factors likely involved e.g. other disease agents • Rare unless other disease agents present Isospora revolta Isospora felis Canine & Feline Coccidiosis • Paratenic hosts – Infections in dogs & cats can be acquired through a paratenic host – Mice, cattle, sheep & other herbivores – Ingest the oocysts & sporozoites invade the extra-intestinal tissue • Mesenteric lymph nodes, brain, muscle – Sporozoites become encysted within tissue & are released when ingested by cats or dogs Canine & Feline Coccidiosis • Control & Treatment – Sanitation to reduce exposure to oocysts – Ensure sufficient colostrum – Reduce stress – Reduce opportunity for hunting • Re: paratenic host – Clinical cases • Supportive therapy • Sulfonamides or amprolium to reduce patent period? – Value? – Response to treatment is seldom dramatic – Treatment of dams prior to parturition ? Super ‘Role’ Model • Barbie says, “Prompt disposal of feces is the key to controlling coccidia!” Cryptosporidiosis Zoonosis • "Coccidian-like" parasite of the Genus Cryptosporidium – Many species • Infect the microvillous region of epithelial cells lining the gastrointestinal & respiratory tracts of many different vertebrates • Intracellular, extra-cytoplasmic parasites of epithelial cells Cryptosporidiosis • Mammals • Cryptosporidium parvum – Infects small intestine – Cats, dogs, horses, cattle & humans... – Very important cause of neonatal diarrhea in calves – Zoonotic • Cryptosporidium hominis – ONLY Infects small intestine of humans – Causes diarrhea Cryptosporidiosis • C. andersoni – Infects the abomasum of ruminants (cattle) • Older calves (>1 month) & mature cattle – May lead to sub-par performance in cattle – Milk production & weight gain – Life-long infections? Cryptosporidiosis • C. bovis – Found in the small intestine – Primary infection in postweaned cattle – BUT: No clinical signs – Life-long infections? – Morphologically identical to C. parvum, therefore confounder... Cryptosporidiosis • C. suis – Morphologically identical to C. parvum – Small & large intestine of swine – ‘Host adapted’ -infects pigs of all ages – No clinical signs • One report in humans – Life-long infections? Cryptosporidiosis • Birds • C. baileyi – Respiratory tract & cloaca of chickens & turkeys • C. meleagridis & C. galli – Small intestine of chickens & turkeys Cryptosporidiosis • Reptiles – Cryptosporidium serpentis • Intestinal infections • Fish – Cryptosporidium molnari • Intestinal infections Morphology • Sporozoites, Merozoites, Meronts & Gamonts – Similar to coccidia • Oocysts – C. parvum - round & very small 4-6 um – C. andersoni - slightly larger 6-8 um – All are sporulated when passed in feces – Immediately infective – Oocysts contain 4 "naked" sporozoites no sporocysts Source: CDC Cryptosporidium life cycle Epidemiology Transmission – Oocysts • Immediately infective, highly resistant & remain viable for months • Standard disinfectant concentrations fail to kill – Ethanol, methanol, sodium hypochlorite, isopropanol... • Methods that “work” – 6% hydrogen peroxide – VIM – High pressure steam cleaning... Epidemiology Transmission • Direct: fecal-oral route is common in confinement Epidemiology Transmission • Waterborne outbreaks are the most common source for human infections Epidemiology Transmission • • • • • • • • Milwaukee - 1993 Kelowna & Cranbrook – 1996 Chilliwack – 1998 North Battleford -2001 Kamloops – 2002 Kansas – 2003 Wausau Wisconsin-2007 Globally, many every year... Epidemiology Prevalence • Worldwide • Infections common – Young animals, neonates & immunocompromised • Dogs & Cats – Reported prevalence of 5-10% – Underestimated... Epidemiology Prevalence • Livestock – Prevalence up to 100% in calves – Calves <3 weeks of age & co-infection rotavirus, coronavirus & E. coli – Dairy > Beef feedlot > Beef on range – Calves: prepatent period is 4-6 days, patent period 714 days – Canadian survey • 17% of horses • 11% of pigs • 23% of sheep ON PEI Beef herds 80% Adults 35%, calves 80% Dairy herds 55% Adults 45%, calves 55% Swine herds 86% Adults 9%, weanlings 40% Epidemiology Prevalence • Poultry – Common wherever birds are raised commercially i.e. disease of confinement – 27% reported in broilers Pathogenesis • Intestinal cryptosporidiosis • Enterocytes of the distal small intestine-ileum • C. parvum - villous atrophy, villous fusion, crypt hyperplasia & enterocyte sloughing – Increased epithelial turnover – Immature population of absorptive cells – Malabsorptive diarrhea Pathogenesis • Intestinal cryptosporidiosis • C. baileyi infects the cloaca & bursa of Fabricius in chickens & turkeys • C. meleagridis intestinal infections Pathogenesis • Abomasal cryptosporidiosis • C. andersoni – Infects gastric peptic glands – Causes dilation of gland & may impact performance Pathogenesis • Respiratory Cryptosporidiosis • C. baileyi – Inhalation or aspiration of oocysts – Impairs mucociliary elevator in trachea & bronchi – Few to no cilia found in heavy infections – Accumulation of mucus & sloughed epithelial cells – Results in air sacculitis & pneumonia Clinical signs • Intestinal cryptosporidiosis • Diarrhea – Typically pasty-yellow in calves, occasionally with blood or mucus – Mild & intermittent or severe profuse & watery – May last up to two weeks – General signs of enteritis & dehydration – Anorexia, abdominal cramping... – Low mortality unless other pathogens or stress factors (severe cold & poor management) are involved Clinical signs • Respiratory cryptosporidiosis • Sneezing, coughing & other signs of respiratory distress Diagnosis • Histopathology – Various stages in sections of ileum as round "blebs" on the microvilli border • Parasitophorous vacuoles Diagnosis • Fecal exam • Sugar-centrifugal fecal flotation – C. parvum oocysts • Round & very small 4-6 um – C. andersoni oocysts • Slightly larger 6-8 um – Both float just under the cover slip – Difficult to see, requires experience – Confused with the abundant yeast – Oocysts may take on a pink refractile appearance Diagnosis • Fecal exam • Staining – Acid fast stain of fixed smears • Oocysts stain red, yeast stain green – Methylene blue & iodine used on wet mounts – Immunofluorescence antibody stain • Specific & sensitive • Limited to diagnostic & research labs Treatment & Control • No treatment currently available – Nothing licensed • Halofuginone & azithromycin some efficacy – Necessary? • Sanitation & good management – Reduce exposure to oocysts • Supportive care – Fluids, electrolytes & reduce stress Treatment & Control • Adequate nutrition – Important, administer in small volumes so as not to overload the gut – Absorptive capacity is reduced during infection • Adequate colostrum – Calves, lambs... • Can be a chronic disease of the immunocompromised & can be life threatening – AIDS patients & immunosuppressive therapy Protozoan Parasites: Heteroxenous Coccidia - Part 1 & 2
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