Risks from Microbes in Foods and Feeds

Risks from Microbes in Foods and Feeds Dr.Kedar Karki. Central Veterinary Laboratory Kathmandu Nepal Human Pathogens Can live as biofilms on leaf surfaces • • • • • • • • • Contamination by water, animal manures, workers, slugs, wild animals • Surface inhabitants – E. coli 0157:H7 – Salmonella – Shigella Listeria E. coli O157:H7 • Leafy greens and sprouts • – Found in intestines of healthy cattle, sheep, goats, deer • – Infected people, rarely asymptomatic • – Produces toxin, Bloody diarrhea • – Often deadly-severe • kidney damage E.Coli O157:H7 on Spinach 2006 baby spinach outbreak – 197 sick, 3 deaths • San Juan and Salinas Valleys of California • Livestock, Watersheds –especially after flooding • – Contamination traced to 4 fields without close water source • – Same strain from infected people – cow manure and wild boar killed in field • • • • Salmonella • Tomatoes and cantaloupe • – Intestinal tracts of humans and other animals • – Diarrhea, blood stream Shigella • Fresh packaged vegetables • – Diarrhea in humans (dysentery) • • Production fields contaminated with sewage • • Poor worker hygiene • – Some strains produce enterotoxin and shiga toxin (similar to E. coli O157:H7) Listeria • Minimally processed vegetables • – Pregnant women, newborns, immuno-compromised • – Soil inhabitant, manure, decaying vegetables, irrigation water (survive 10-12 years in plant material) • – fever, muscle aches, and sometimes gastrointestinal symptoms such as nausea or diarrhea • – If infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance, or convulsions Hepatitis A • Contaminated Vegetables • – Sewage contaminated irrigation, processing water • – Infected workers – picking and processing Infective for 3 weeks • – Washing vegetables relatively ineffective • • Enteric virus • – fever, malaise, anorexia, nausea, dark urine, and jaundice Cryptospiridium • Contaminated raspberries fro Guatemala • • Water-borne parasitic protazoanwash water • • upset stomach, diarrhea, cramps, weight loss, dehydration, and sometimes fever • • Lives on surfaces for extended periods of time - oocysts Cyclospora • Berries, lettuce, basil • • Protazoan parasite • – watery and sometimes explosive diarrhea, loss of appetite, weight loss, nausea, gas, stomach cramps, muscle ache, vomiting, low grade fever, bloating and fatigue • • Contaminated workers • – cultivation, harvest, packaging or transportation through contact with contaminated water or workers Mycotoxins andWhere They are Found Mycotoxins-history • 1960 Turkey X-peanut meal killed 100,000 turkey poults and • ~20,000 other fowl-alfatoxin identifiedreproduced symptoms with aflatoxin • – 1974-India, 2004 Kenya • – 1999, 2005 and 2006-pet foods • • Holy Fire/St. Anthony’s Fire-Ergot PoisoningNorthern • Europe/North America-outbreaks recorded from middle ages till present • 1941-1947-Alimentary Toxic AleukiaRussia-Central Asia-wheat, barley, prosomillet overwintered in fieldtrichothecene toxins from Fusarium sp. estimate 10,000-30,000 people died • • 1934 midwest >5000 horses died from “moldy corn disease”• Fumonisins • – Human poisonings in Africa, China, USA • 1972- DON/zearalenone in corn-swine feed refusal-reproductive problems • – Fusarium Head Blight Problems of last decade • • Yellow rice diease-Acute Cardiac Beriberi-Penicillium toxins- Asia • • Balkan Endemic NephropathyOchratoxins Barley Ergot • Ergot alkaloids • Ergots can be found in Wheat, barley, rye, triticale and many wild and domesticated grasses Ergot • Common in almost all grasses if cool, wet weather predominates during anthesis • • Grain >0.05% ergot is ergoty and cannot be sold-clean • • Levels > 0.1% ergot in complete rations will likely have effects on animal performance. • • All warm blooded animals are sensitive • • Common in rye, triticale, some wheat (Waldron) and barley varieties • • Watch pastures where grasses have mature seeds. • Animals often attracted to honey-dew stage Effects in Animals • Sometimes the dose is hard to evaluate with mycotoxins because • ����the presence of Mycotoxins may be very uneven in feeds (i.e., hotspots), • ����clinical signs in animals from mycotoxin exposure can be vague and may appear long after the feed has been consumed. • ����Generally reduced feed efficiency is first sign • ����Diarrhea-sometimes bloody • ����Vaccine failure • ����Reproduction failure Fumonisins • • • • 1988 Gelderblom et. al • South Africa, esophageal cancer • Intense interest because fumonisisns are found in measurable concentrations in corn from all over the world Toxicology of FUMONISIN (FB1) • Horses: equine leukoencephalomalacia (ELEM) • Pigs: liver damage and porcine pulmonary edema (PPE) Aflatoxins • Carcinogen-dose makes the poison-allow 20ppb in human foods-(peanut butter) • • Most common where drought damage, high temperatures occur-e.g. southern US, hail damage, bird, insect damage • • Can develop in field or storage-cereals, cottonseed, processed feeds. • • Poultry, swine, horses, dogs more susceptible than ruminants-aflatoxin into milk @ 1% of feed dose • – U.S. Pet food recalls due to aflatoxin poisonings 1999, 2005, 2006 Ochratoxins/Citrinin/Pen icillic acid, Patulin • Nephrotoxic- Kidney • Carcinogen • Immunosuppressor • Poultry and swine are the most sensitive livestock • • Can have residues in meat, processed meats, apple juices, dried apples • • • • Other Mycotoxins • • Sterigmatocystin -Aspergilus versicolor, A. fumigatus, • A. nidulans, A. terrus, A. sydowii, A.glaucus • – Most common mycotoxin in Canada-stored wheat and other grains • – Rarely tested for in USA • – Carcinogenic, liver cancers-”aflatoxin light” • • Alternaria toxins -Alternaria alternata, A. triticina • – Found in wet weather delayed harvest wheat • – Toxins –alternariol, altenuene, altertoxin and tenuazonic acid are found in bread products made from contaminated wheat Stachybotrys chartarum • • Mycotoxins: found in spores-intoxication via inhalation • – Trichothecenes: verrucarins B and J, roridin E, satratoxins F, G, H, and G-generally only analyze for verrucarin B • – Stachylysin and many others • • Potent inhibitors of protein and DNA synthesis • • Dermatitis, chest and upper airway symptoms including pulmonary hemorrhage, inflamation of oral cavity, rhinitis, conjuctivitis, neurological disorders • • Symptoms w/in 2-3 days of exposure-may last w/out new exposure for 3 weeks!!- use care in handling samples