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Food Borne Infections Organisms do not have to grow in the food before it is eaten: Food Borne Infections • Organisms do not have to grow in the food before it is eaten: Bacteria Typhoid Cholera TB Brucellosis Q-fever Anthrax Viruses Hepatitis A Polio Anual incidence Rotavirus Enteroviruses Parasites Amoeboid disentry Toxoplasmosis Giardia lamblia Cryptosporidium Nematode Helminths Typhoid fever – Diagnosis of typhoid fever Blood cultures are positive during the first week and after the second week Stool cultures and sometimes urine cultures are positive after the second week The Widal test is a serological test for antibodies against Salmonella typhi. 10% of those infected become short term carriers and a smaller % become long-term carriers due to persistence of the bacteria in the gallbladder or urinary bladder. S. typhi /typhoid cases in NZ from 1980 to 2004 Typhoid Number of cases 35 30 25 20 15 10 5 2004 2002 2000 1998 1996 1994 1992 1990 1988 1986 1984 1982 1980 0 fever Year Salmonellosis cases in NZ from 1980 to 2004 3000 2000 Salmonellosis 1500 1000 500 Year 2004 2002 2000 1998 1996 1994 1992 1990 1988 1986 1984 1982 0 1980 Number of cases 2500 Other Bacteria TB Brucellosis Q-fever Anthrax Incidence of TB • Tuberculosis (TB) remains the leading cause of death • • • • worldwide from a single infectious disease agent. Indeed up to 1/2 of the world's population is infected with TB. The registered number of new cases of TB worldwide roughly correlates with economic conditions: the highest incidences are seen in those countries with the lowest gross national products. WHO estimates that eight million people get TB every year, of whom 95% live in developing countries. An estimated 2 million people die from TB every year. Mortality • It is estimated that between 2000 and 2020, nearly one • • billion people will be newly infected, 200 million people will get sick, and 35 million will die from TB After a century of decline TB is increasing and there are strains emerging which are resistant to antibiotics. This excess of cases is attributable to the changes in the social structure in cities, the human immunodeficiency virus epidemic, and failure of most cities to improve public health programs, and the economic cost of treating. HISTORY • TB is an ancient infectious disease caused by Mycobacterium tuberculosis. • It has been known since 1000 B.C., • Since TB is a disease of respiratory transmission, optimal conditions for transmission include: – overcrowding – poor personal hygiene – poor public hygiene 1/2 of the world's population is infected • With the increased incidence of AIDS, TB has • become more a problem in the U.S., and the world. It is currently estimated that 1/2 of the world's population (3.1 billion) is infected with Mycobacterium tuberculosis. • Mycobacterium avium complex is associated with AIDS related TB. Brucella spp. • Gram negative, coccobacilli bacteria • Facultative, intracellular organism • Environmental persistence – Temp, pH, humidity – Frozen and aborted materials • Multiple species Center for Food Security and Public Health Iowa State University - 2004 Species Biovar/ Serovar Natural Host Human Pathogen B. abortus 1-6, 9 cattle yes B.melitensis 1-3 goats, sheep yes B. suis 1, 3 swine yes 2 hares yes 4 reindeer, caribou yes 5 rodents yes B. canis none dogs, other canids yes B. ovis none sheep no B. neotomae none Desert wood rat no B. maris marine mammals Center for Food Security and ? Health Iowa State Public University - 2004 The Many Names of Brucellosis Human Disease • • • • • Malta Fever Undulant Fever Mediterranean Fever Rock Fever of Gibraltar Gastric Fever Animal Disease • • • • • • Bang’s Disease Enzootic Abortion Epizootic Abortion Slinking of Calves Ram Epididymitis Contagious Abortion Center for Food Security and Public Health Iowa State University - 2004 Professor FEG Cox. The Wellcome Trust, Illustrated History of Tropical Diseases Sir David Bruce (1855-1931) •British Army physician and microbiologist who discovered Micrococcus melitensis Center for Food Security and Public Health Iowa State University - 2004 Transmission to Humans • Conjunctiva or broken skin contacting infected tissues – Blood, urine, vaginal discharges, aborted fetuses, placentas • Ingestion – Raw milk & unpasteurized dairy products – Rarely through undercooked meat Center for Food Security and Public Health Iowa State University - 2004 Transmission to Humans • Inhalation of infectious aerosols – Pens, stables, slaughter houses • Inoculation with vaccines – B. abortus strain 19, RB-51 – B. melitensis Rev-1 – Conjunctival splashes, injection • Person-to-person transmission is very rare • Incubation varies – 7-21 days to several months Center for Food Security and Public Health Iowa State University - 2004 Center for Food Security and Public Health Iowa State University - 2004 B. melitensis • Latin America, Middle East, • Mediterranean, eastern Europe, Asia, and parts of Africa Accounts for most human cases – In the Mediterranean and Middle East • Up to 78 cases/100,000 people/year • Arabic Peninsula 20% seroprevalence • Recent emergence in cattle on Middle Eastern intensive dairy farms Center for Food Security and Public Health Iowa State University - 2004 B. abortus • Worldwide • Some countries have eradicated • Notifiable disease in many countries – Poor surveillance and reporting due to lack of recognition – Fever of Unknown Origin (FUO) Center for Food Security and Public Health Iowa State University - 2004 B. suis • Biovars 1 and 3 – Worldwide problems where swine are raised • Free – United Kingdom, Canada • Eradicated – Holland, Denmark • Low Incidence – Middle East, North Africa Center for Food Security and Public Health Iowa State University - 2004 B. canis • Poorly understood • 1-19% prevalence in United States • Rarely causes disease in humans Center for Food Security and Public Health Iowa State University - 2004 Brucellosis in U.S.: 1972-2002 350 Reported Cases 300 250 200 150 100 50 0 1972 2002 1977 1982 1987 Year Security and Center for Food Public Health Iowa State University - 2004 1992 1997 Brucellosis • United States – Approximately 100 cases per year – Less than 0.5 cases/100,000 people – Mostly California, Florida, Texas, Virginia – Many cases associated with consumption of foreign cheeses Center for Food Security and Public Health Iowa State University - 2004 Prognosis • May last days, months or years • Recovery is common • Disability is often pronounced • About 5% of treated cases relapse • Failure to complete the treatment regimen • Sequestered infection requiring surgical drainage • Case-fatality rate: <2% ( untreated) – Endocarditis caused by B. melitensis Center for Food Security and Public Health Iowa State University - 2004 Human Disease • Neurological – Depression, mental fatigue • Cardiovascular – Endocarditis resulting in death • Chronic brucellosis is hard to define – Length, type and response to treatment variable – Localized infection • Blood donations of infected should not be accepted Center for Food Security and Public Health Iowa State University - 2004 •Q Fever The Organism • Coxiella burnetii – Rickettsial agent – Obligate intracellular parasite – Stable and resistant – Killed by pasteurization – Two antigenic phases • Phase 1: virulent • Phase 2: less pathogenic Center for Food Security and Public Health Iowa State University - 2004 History • 1935 – 1st described in Queensland, Australia – Found in ticks in Montana • Outbreaks – Among military troops • When present in areas infected animals – Cities and towns • Downwind from farms Center for Food Security and • By roads traveled by animals Public Health Iowa State University - 2004 with Transmission • Aerosol – Parturient fluids • 109 bacteria per gram of placenta – Urine, feces, milk – Wind-borne • • • • Direct contact Fomites Ingestion Center for Food Security and Arthropods (ticks) Public Health Iowa State University - 2004 Transmission • Person-to-person (rare) – Transplacental (congenital) – Blood transfusions – Bone marrow transplants – Intradermal inoculation – Possibly sexually transmitted Center for Food Security and Public Health Iowa State University - 2004 Epidemiology • Worldwide – Except New Zealand • Reservoirs – Domestic animals • Sheep, cattle, goats • Dogs, cats – Birds – Reptiles Center for Food Security and – Wildlife Public Health Iowa State University - 2004 Epidemiology • Occupational and environmental hazards – Farmers, producers – Veterinarians and technicians – Meat processors, abattoir – Laboratory workers Center for Food Security and Public Health Iowa State University - 2004 Human Disease • Incubation: 2-5 weeks • One organism may cause disease • Humans are dead-end hosts – Usually show clinical signs of illness • Disease – Asymptomatic (50%) – Acute – Chronic Center for Food Security and Public Health Iowa State University - 2004 Acute Infection • Flu-like, self limiting • Atypical pneumonia (30-50%) – Non-productive cough, chest pain – Acute respiratory distress possible • Hepatitis • Skin rash (10%) • Other signs (< 1%) – Myocarditis, pericarditis, meningoencephalitis • Death: 1-2% Center for Food Security and Public Health Iowa State University - 2004 Chronic Disease • 1-5% of those infected – Prior heart disease, pregnant women, immunocompromised • Endocarditis • Other – Osteomyelitis – Granulomatous hepatitis – Cirrhosis • 50% relapse rate after antibiotic therapy Center for Food Security and Public Health Iowa State University - 2004 Risk to Pregnant Women • Most asymptomatic • Transplacental transmission • Reported complications – In-utero death – Premature birth – Low birth weight – Placentitis – Thrombocytopenia Center for Food Security and Public Health Iowa State University - 2004 Prognosis • Overall case-fatality rate <1 - 2.4% • 50% cases self-limiting • Only 2% develop severe disease • Active chronic disease – Usually fatal if left untreated – Fatality for endocarditis: 35-55% – 50-60% need valve replacement Center for Food Security and Public Health Iowa State University - 2004 Case • Male dairy farmer – Age 46 – Sudden onset • Fever, chills, cough • Weight loss – Initially thought it was influenza – Symptoms persisted for 2 weeks – Presented to emergency room • Again influenza was the diagnosis Center for Food Security and Public Health Iowa State University - 2004 Large Animal Case • Referral to infectious disease specialist – Tested positive for Q fever – Antibiotics for 5 days – Resolved in 2 weeks • Epidemiology – No recent calvings on his farm – Two beef cattle herds across the road • 2 out of 14 tested positive for Q fever Center for Food Security and Public Health Iowa State University - 2004 Small Animal Case • 1985, Nova Scotia, Canada – 33 cases of Q fever • 25 were exposed to cat • 17 developed cough • 14 developed pneumonia – Most common symptoms • Fever, sweats, chills, fatigue, myalgia, headache – Cat tested positive for C. burnetii • 1:152 to phase I antigen • 1:1024 to phase II antigen Center for Food Security and Public Health Iowa State University - 2004 Animal Disease • Sheep, cattle, goats – Usually asymptomatic – Reproductive failure • Abortions, stillbirths • Retained placenta • Infertility • Weak newborns • Low birth weights • Mastitis in dairy cattle – Carrier state Center for Food Security and Public Health Iowa State University - 2004 Animal Disease • Other animal species – Dogs, cats, horses, pigs, camels, buffalo, pigeons, other fowl – Asymptomatic – Reproductive failure • Laboratory Animals – Rats, rabbits, guinea pigs, hamsters – Varies from asymptomatic to fever, Center for Food Security and granulomas, or death Public Health Iowa State University - 2004 Morbidity and Mortality • Prevalence unknown – Endemic areas • 18-55% of sheep with antibodies • 82% of dairy cattle • Morbidity in sheep: 5-50% Center for Food Security and Public Health Iowa State University - 2004 Prevention and Control • Pasteurization • Vaccination – Human and animal – Not available in U.S. • Eradication not practical – Too many reservoirs – Constant exposure – Stability of agent in environment Center for Food Security and Public Health Iowa State University - 2004 Prevention and Control • Education – Sources of infection • Good husbandry – Disposal of birth products (incinerate) • Lamb indoors in separate facilities – Disinfection • 0.05% chlorine • 1:100 Lysol • Isolate new animals Center for Food Security and Public Health Iowa State University - 2004 Anthrax • How heat resistant is Bacillus anthracis (B. Anthracis)? Spores • Moist heat resistance • D value at 90ºC (194ºF) - 2.5-7.5 minutes • D value at 95ºC (203ºF) - 1.7-4.2 minutes • Not That much killed with thorough cooking Epidemiology of Anthrax in Animal and Human Hosts Clinical Presentation of Anthrax Gastrointestinal (Ingestion) Anthrax Virtually 100% fatal Abdominal pain Hemorrhagic ascites Paracentesis fluid may reveal gram-positive rods Treatment & Prophylaxis Treatment • Penicillin is drug of choice • Erythromycin, chloramphenicol acceptable alternatives • Doxycycline now commonly recognized as prophylactic Vaccine (controversial) Laboratory workers Employees of mills handling goat hair Active duty military members Potentially entire populace of U.S. for herd immunity