Dec. 1, 1997
Salmonellosis (Public Health Concerns for the Farm Family and Staff)
FACT SHEET (12/1/97) #1
What is salmonellosis?
Salmonellosis is an infection caused by the bacterium Salmonella enterica, which has over 2,000 serotypes (for example Salmonella Typhimurium). Salmonella bacteria are found in the gastrointestinal tracts of many species of animals, birds, reptiles, and humans, and also in the environment, which may be contaminated by the feces of animals and people.
How is it spread?
Most times salmonella bacteria’s “route of entry” into a “host ( human or animal)” is “oral,” i.e., the host ingests salmonella bacteria directly (“fecal-oral”) or indirectly (“fecal-fomite/food-oral”). For example it is possible to come into direct contact with manure if dirty hands are used to wipe your face/mouth/eyes, when smoking, or even to get splashed with manure in the face from a cow’s tail. It is also possible to indirectly come into oral contact with Salmonella on a fomite (inanimate object) that has been contaminated with salmonella bacteria, such as a soiled cigarette, a cup, a pen placed into the mouth, and especially when eating food or drinking fluids contaminated with fecal matter. For a cow, most often they ingest salmonellae in their water or feed, or they come into oral contact with the barn environment (various surfaces, freestall floor, etc.).
Conditions under which salmonella survive in the environment?
Salmonella bacteria love wet environments shielded from the sun. They have the remarkable ability to survive under adverse conditions. They survive between the pH’s of 4 to 8+, and can grow between 8 and 45 C. Salmonella are facultative anaerobic bacteria that can survive under low oxygen tension such as in manure slurry pits. Salmonella are known to survive for long periods in soil and in water. Salmonellae spread onto fields in the form of manure may survive for long periods; it is best to spread the manure onto flat land (to prevent runoff problems) where it is exposed to the drying effects of wind, and to the bactericidal effect of UV irradiation from the sun; manure should be spread onto cropland rather than onto pastures for grazing. There has been much recent investigation into the advantages of different manure disposal methods; composting has many advantages from the standpoint of controlling disease. Salmonellae are no more or less sensitive to the effects of commonly used disinfectants than are other fecal bacteria. Chlorine solutions, iodines, quaternary ammoniums, phenolics, etc., are very good at killing salmonellae on surfaces; however, efficient scraping/dry cleaning is important to get rid of organic matter and bedding, followed by wet cleaning with high pressure hot water/steam and then disinfection. The interval between wet cleaning and disinfection must not be too long or salmonellae can “bloom” in the wet environment. Many strains are relatively resistant to the effects of drying, salting and smoking of foods. However, salmonellae are very sensitive to beta and gamma irradiation.
What are the symptoms of salmonella infection in humans?
Once Salmonella has been ingested, the “incubation time” or period from ingestion until the first symptoms of illness occur ranges from 12 to 72 hours. The time to illness may vary depending on many things such as the host’s overall fitness and age, the amount and serotype of Salmonella ingested (with some serotypes as few as 20 cells), and the presence of various “stress” factors such as whether the person is undernourished, etc.
Most often humans have a “gastroenteritis” syndrome characterized by nausea, vomiting within 8-48 hours of ingesting Salmonella. Shortly thereafter the patient will experience abdominal pain/colic or cramps and diarrhea; the diarrhea may vary from a few loose stools, to profuse watery stools, to rarely dysentery (bloody stools) with much straining. Patients may have moderate fevers (<39C) and occasional chills, too. The duration of symptoms is also dependent on host factors, dose ingested and type of salmonellae.
More severe symptoms may occur in higher risk groups of people.
People at higher risk of infection are as follows:
1. Those at extremes of age (the young because their immune systems are immature as is their bacterial flora in their gastrointestinal tract, both of which are protective; and the aged because their immune systems are waning or declining);
2. Persons with decreased gastric acidity (stomach acid is a first line of defense against ingested Salmonella), which may include those taking antacids, acid suppression drugs (e.g., H2 blockers), or those without stomachs due to cancer or ulcer surgery;
3. Persons with altered gastrointestinal bacteria (which is another protective mechanism to compete against Salmonella bacteria) which may include those taking broad spectrum antibiotics, purgatives or those who have had bowel surgery;
4. Persons who are immunosuppressed or immunocompromised (HIV patients, those taking cytotoxic drugs such as cancer patients, those with rheumatoid arthritis, those with inflammatory bowel disease, those who have had transplants, those with bleeding disorders such as Sickle Cell patients, those with bone or joint disease, especially prostheses, those with anatomic cardiovascular disease);
5. Persons taking opiate drugs in which the bowel motility is decreased (the normal bowel movement or peristalsis is another protective mechanism to prevent the establishment of pathogenic bacteria such as Salmonella in the host’s bowel).
In these higher risk groups of people, Salmonella may invade beyond the gastrointestinal tract to cause severe systemic illness (called “bacteremia” or bacteria in the bloodstream, and then “septicemia” or bacteria spreading from the bloodstream to deeper internal tissues of the body). These syndromes would cause more severe symptoms such as more extreme nausea, prolonged fever, chronic diarrhea and overall lethargic feeling; in some cases death may ensue as a sequella to salmonella infection.
There are also chronic forms of salmonellosis that may involve various organs systems of the body including the joints and vascular systems.
What are some measures to take to safeguard the health of farm families and staff?
- know the symptoms of salmonellosis in humans;
- alert employees working with cattle of the risk of salmonellosis from animal and farm contact;
- avoid contact with feces, wear protective clothing that can be disinfected or changed between affected areas of the farm;
- use properly maintained foot baths for disinfecting boots;
- urge all farm staff to observe good personal hygiene precautions;
- avoid exposure of other household members to soiled barn clothing by keeping these clothes out of the house; wash hands after working in barn areas;
- no eating or smoking in the barn environment;
- do not drink raw milk from the bulk tank (Salmonella is shed via milk in acute cases of disease in cattle); pasteurize or better yet buy retail milk for the next two or so months (timing depends on the number of new cases and their frequency of occurrence in the herd);
- keep “high risk individuals” out of the barn environment or in contact with cattle and/or their waste products.
If you become ill with any of these symptoms (vomit, fever, diarrhea, cramps ... in any combination) seek medical attention, call your physician; take along this fact sheet with you to the doctor’s office or emergency room:
- salmonellosis can be diagnosed by bacterial culture (stool and/or blood cultures);
- you may need supportive medical care (fluid and electrolyte replacement) for disease management;
- you may need hospitalization depending on the degree of debilitation from diarrhea, etc.;
- antimicrobial drugs are usually reserved for treatment of severely ill persons who have systemic (septicemic) disease; use of these drugs necessitates laboratory testing of the salmonellae to see what drugs they are sensitive to.
Work with your veterinarian on immediate (short-term) controls and long-term preventive measures for reducing the problem of salmonellosis in your herd (fact sheets 3 and 4);
* the Diagnostic Laboratory at Cornell is ready to assist your veterinarian with these measures; cooperative agreements are in effect with various other Cornell Colleges and Departments, with the NY State Department of Agriculture and Markets Division of Animal Industry, with the Northeast Center for Agriculture and Occupational Health (Bassett Healthcare), with the N.Y. State Department of Health, and various federal government agencies (CDC, FDA-CVM, USDA) to study this ongoing salmonella problem and to reduce the risk of salmonella infections in our livestock industries.
FACT SHEET (12/1/97) #2
For Use in Herds With “Suspect” Salmonella Typhimurium DT104 Infections in Cattle- Public Health Concerns for the Farm Family and Staff
1. Salmonellae are highly infectious bacteria that cause a variety of symptoms in people including vomiting, fever, diarrhea, cramps; certain groups are at a higher risk of infection than the normal healthy adult, often with serious consequences; these individuals need special attention.
High Risk Groups for Salmonella Infection:
- extremes of age (the young and the elderly; the young have a poorly developed microbial gut flora which is protective in the adult; elderly may have waning immune systems or weak gastric acidity)
- immunosuppressed (on anticancer/cytotoxic drugs; some anti- arthritis drugs)
- immunocompromised (HIV+)
- taking (oral) antimicrobial drugs (destroys the “normal,” protective gut bacterial flora leaving the person open to colonization by pathogenic salmonellae)
- taking antacids or acid suppression drugs
- persons with gastrectomies (surgical removal of stomach)
S. Typhimurium is the most common isolate from spontaneous disease cases in cattle (i.e., ill cattle); it is not common in apparently well cattle not showing signs of depression and diarrhea (from the NAHMS surveys and the USDA, APHIS, VS, NVSL Salmonella Surveillance Program);
The Salmonella Typhimurium Definitive Type 104 (DT104) is an emerging multi-drug resistant strain of Salmonella Typhimurium that was first reported in the United Kingdom in 1984;
DT104 is occurring more frequently in N.Y. state in cattle and in other animals and birds; we have had culture-confirmed DT104 infections in N.Y. state animals since at least 1993 (found through a retrospective analysis of salmonella strains saved at Cornell's Diagnostic Laboratory);
DT104 causes severe disease in cattle;
DT104 causes particularly severe disease in humans (more hospitalizations, more blood-borne infections);
DT104 is multiply-antibiotic resistant; the resistance is stable, i.e., doesn’t need the selective pressure of antibiotic usage for it to be maintained; the epidemic strains of DT104 are commonly resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides and tetracyclines;
DT104 disease in humans is related, so far in the United States and in New York, to occupational exposure (veterinarians and farm families/staff who have contact with sick calves and older cattle, and who drink raw milk);
In the United Kingdom there have also been food-borne disease cases in humans eating contaminated meats (chicken, beef, pork, lamb);
DT104 has been isolated, however, from an increasing spectrum of animal species ... so the potential to spread disease to humans exists from other animal too;
2. Stop drinking raw milk from the bulk tank!!! (Salmonella is shed via milk in acute cases of disease in cattle); pasteurize or better yet, buy retail milk for the next 1-2 months (timing depends on the number of new cases and their frequency of occurrence in the herd)
3a. Keep “high risk individuals” out of the barn environment or in contact with cattle and/or their waste products;
3b. Wear protective clothing that can be disinfected or changed between affected areas of the farm (boots, coveralls);
3c. Wash hands after working in barn areas; improve general personal hygiene;
3d. No eating or smoking in the barn environment or when working with animals;
4. See the fact sheet on general salmonellosis in humans (Fact sheet #1);
5. If you become ill with any of these symptoms (vomit, fever, diarrhea, cramps ... in any combination) seek medical attention, call your physician; take along this fact sheet with you to the doctor’s office or emergency room; salmonellosis can be diagnosed by culture (stool and/or blood cultures); you may need supportive medical care (fluid and electrolyte replacement) for disease management; antimicrobial drugs are usually reserved for treatment of severely ill persons who have systemic (septicemic) disease; use of these drugs necessitates testing of the salmonellae to see what drugs they are sensitive to.
6. Work with your veterinarian on immediate (short-term) controls and long-term preventive measures for reducing the problem of salmonellosis in your herd;
* the Diagnostic Laboratory at Cornell is ready to assist your Veterinarian with these measures; cooperative agreements are in effect with various other Cornell Colleges and Departments, with the New York State Department of Agriculture and Markets Division of Animal Industry, with the Northeast Center for Agriculture and Occupational Health (Bassett Healthcare), with the New York State Department of Health, and various federal government agencies (CDC, FDA-CVM, USDA) to study this ongoing salmonella problem and to reduce the risk of salmonella infections in our livestock industries.
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