Salmonellosis is a symptomatic infection caused by bacteria of the Salmonella type. The most common symptoms are diarrhea, fever, abdominal cramps, and vomiting. Symptoms typically occur between 12 hours and 36 hours after exposure, and last from two to seven days. Occasionally more significant disease can result in dehydration. The old, young, and others with a weakened immune system are more likely to develop severe disease. Specific types of Salmonella can result in typhoid fever or paratyphoid fever.
There are two species of Salmonella: Salmonella bongori and Salmonella enterica with many subspecies. Infection is usually spread by eating contaminated meat, eggs, or milk. Other foods may spread the disease if they have come into contact with manure. A number of pets including cats, dogs, and reptiles can also carry and spread the infection. Diagnosis is by a stool test or blood tests.
Efforts to prevent the disease include the proper washing, preparation, and cooking of food. Mild disease typically does not require specific treatment. More significant cases may require treatment of electrolyte problems and intravenous fluid replacement. In those at high risk or in whom the disease has spread outside the intestines, antibiotics are recommended.
Salmonellosis is one of the most common causes of diarrhea globally. In 2015, 90,300 deaths occurred from nontyphoidal salmonellosis, and 178,000 deaths from typhoidal salmonellosis. In the United States, about 1.2 million cases and 450 deaths occur from nontyphoidal salmonellosis a year. In Europe, it is the second most common foodborne disease after campylobacteriosis.
|Electron micrograph showing Salmonella typhimurium (red) invading cultured human cells|
|Symptoms||Diarrhea, fever, abdominal cramps, vomiting|
|Complications||Reactive arthritis, irritable bowel syndrome|
|Usual onset||0.5–3 days post exposure|
|Risk factors||Old, young, weak immune system, bottle feeding, proton pump inhibitors|
|Diagnostic method||Stool test, blood tests|
|Differential diagnosis||Other types of gastroenteritis|
|Prevention||Proper preparation and cooking of food|
|Treatment||Fluids by mouth, intravenous fluids, antibiotics|
|Frequency||1.2 million non–typhoidal cases per year (US)|
After a short incubation period of a few hours to one day, the bacteria multiply in the small intestine, causing an intestinal inflammation (enteritis). Most people with salmonellosis develop diarrhea, fever, vomiting, and abdominal cramps 12 to 72 hours after infection. Diarrhea is often watery and non-bloody but may be mucoid and bloody. In most cases, the illness lasts four to seven days, and does not require treatment. In some cases, though, the diarrhea may be so severe that the patient becomes dangerously dehydrated and must be hospitalized. At the hospital, the patient may receive fluids intravenously to treat the dehydration, and may be given medications to provide symptomatic relief, such as fever reduction. In severe cases, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites, and can cause death, unless the person is treated promptly with antibiotics.
In otherwise healthy adults, the symptoms can be mild. Normally, no sepsis occurs, but it can occur exceptionally as a complication in the immunocompromised. However, in people at risk such as infants, small children, and the elderly, Salmonella infections can become very serious, leading to complications. In infants, dehydration can cause a state of severe toxicity. Extraintestinal localizations are possible, especially Salmonella meningitis in children, osteitis, etc. Children with sickle-cell anemia who are infected with Salmonella may develop osteomyelitis. Treatment of osteomyelitis, in this case, will be to use fluoroquinolones (ciprofloxacin, levofloxacin, etc., and nalidixic acid).
Those whose only symptom is diarrhea usually completely recover, but their bowel habits may not return to normal for several months.
Typhoid fever occurs when Salmonella bacteria enter the lymphatic system and cause a systemic form of salmonellosis. Endotoxins first act on the vascular and nervous apparatus, resulting in increased permeability and decreased tone of the vessels, upset thermal regulation, vomiting, and diarrhea. In severe forms of the disease, enough liquid and electrolytes are lost to upset the fluid balance, cause an electrolyte imbalance, decrease the circulating blood volume and arterial pressure, and cause hypovolemic shock. Septic shock may also develop. Shock of mixed character (with signs of both hypovolemic and septic shock) are more common in severe salmonellosis. Oliguria and azotemia develop in severe cases as a result of renal involvement due to hypoxia and toxemia.
A small number of people afflicted with salmonellosis experience reactive arthritis, which can last months or years and can lead to chronic arthritis. In sickle-cell anemia, osteomyelitis due to Salmonella infection is much more common than in the general population. Though Salmonella infection is frequently the cause of osteomyelitis in people with sickle-cell, it is not the most common cause, which is Staphylococcus infection.
Those infected may become asymptomatic carriers, but this is relatively uncommon, with shedding observed in only 0.2 to 0.6% of cases after a year.
Salmonella bacteria can survive for some time without a host; they are frequently found in polluted water, with contamination from the excrement of carrier animals being particularly important.
An estimated 142,000 Americans are infected each year with Salmonella Enteritidis from chicken eggs, and about 30 die. The shell of the egg may be contaminated with Salmonella by feces or environment, or its interior (yolk) may be contaminated by penetration of the bacteria through the porous shell or from a hen whose infected ovaries contaminate the egg during egg formation.
Nevertheless, such interior egg yolk contamination is theoretically unlikely. Even under natural conditions, the rate of infection was very small (0.6% in a study of naturally contaminated eggs and 3.0% among artificially and heavily infected hens).
The US Food and Drug Administration (FDA) has published guidelines to help reduce the chance of food-borne salmonellosis. Food must be cooked to 145–165 °F (63–74 °C), and liquids such as soups or gravies should be boiled when reheating. Freezing kills some Salmonella, but it is not sufficient to reliably reduce them below infectious levels. While Salmonella is usually heat-sensitive, it acquires heat-resistance in high-fat environments such as peanut butter.
Antibodies against nontyphoidal Salmonella were first found in Malawi children in research published in 2008. The Malawian researchers identified an antibody that protects children against bacterial infections of the blood caused by nontyphoidal Salmonella. A study at Queen Elizabeth Hospital in Blantyre found that children up to two years old develop antibodies that aid in killing the bacteria. This could lead to a possible Salmonella vaccine for humans.
A 2014 study tested a vaccine on chickens which offered efficient protection against salmonellosis.
Vaccination of chickens against Salmonella essentially wiped out the disease in the United Kingdom. A similar approach was considered in the United States, but the Food and Drug Administration decided not to mandate vaccination of hens.
Since 2011, Denmark has had zero cases of human salmonella poisoning. The country eradicated salmonella without vaccines and antibiotics by focusing on eliminating the infection from "breeder stocks", implementing various measures to prevent infection, and taking a zero-tolerance policy towards salmonella in chickens.
Electrolytes may be replenished with oral rehydration supplements (typically containing salts sodium chloride and potassium chloride).
Appropriate antibiotics, such as ceftriaxone, may be given to kill the bacteria, but are not necessary in most cases. Azithromycin has been suggested to be better at treating typhoid in resistant populations than both fluoroquinolone drugs and ceftriaxone. There are recommendations on choice of antibiotic to avoid promoting antibiotic resistance.
In 2010, an analysis of death certificates in the United States identified a total of 1,316 Salmonella-related deaths from 1990 to 2006. These were predominantly among older adults and those who were immunocompromised. The U.S. government reported as many as 20% of all chickens were contaminated with Salmonella in the late 1990s, and 16.3% were contaminated in 2005.
The United States has struggled to control salmonella infections, with the rate of infection rising from 2001 to 2011. In 1998, the USDA moved to close plants if salmonella was found in excess of 20 percent, which was the industry’s average at the time, for three consecutive tests. Texas-based Supreme Beef Processors, Inc. sued on the argument that Salmonella is naturally occurring and ultimately prevailed when a federal appeals court affirmed a lower court. These issues were highlighted in a proposed Kevin's Law (formally proposed as the Meat and Poultry Pathogen Reduction and Enforcement Act of 2003), of which components were included the Food Safety Modernization Act passed in 2011, but that law applies only to the FDA and not the USDA. The USDA proposed a regulatory initiative in 2011 to Office of Management and Budget.
An outbreak of salmonellosis started in Northern Europe in July 2012, caused by Salmonella thompson. The infections were linked to smoked salmon from the manufacturer Foppen, where the contamination had occurred. Most infections were reported in the Netherlands; over 1060 infections with this subspecies and four fatalities were confirmed.
A case of widespread infection was detected mid-2012 in seven EU countries. Over 400 people had been infected with Salmonella enterica serovar Stanley (S. Stanley) that usually appears in the regions of Southeast Asia. After several DNA analyses seemed to point to a specific Belgian strain, the "Joint ECDC/E FSA Rapid Risk Assessment" report detected turkey production as the source of infection.
In Germany, food poisoning infections must be reported. Between 1990 and 2005, the number of officially recorded cases decreased from about 200,000 to about 50,000.
In March 2007, around 150 people were diagnosed with salmonellosis after eating tainted food at a governor's reception in Krasnoyarsk, Russia. Over 1,500 people attended the ball on March 1 and fell ill as a consequence of ingesting Salmonella-tainted sandwiches.
About 150 people were sickened by Salmonella-tainted chocolate cake produced by a major bakery chain in Singapore in December 2007.
Both salmonellosis and the microorganism genus Salmonella derive their names from a modern Latin coining after Daniel E. Salmon (1850–1914), an American veterinary surgeon. He had help from Theobald Smith, and together they found the bacterium in pigs.
The "Four-inch regulation" or "Four-inch law" is a colloquial name for a regulation issued by the U.S. FDA in 1975, restricting the sale of turtles with a carapace length less than four inches (10 cm).
The regulation was introduced, according to the FDA, "because of the public health impact of turtle-associated salmonellosis". Cases had been reported of young children placing small turtles in their mouths, which led to the size-based restriction.
The U.S. Food and Drug Administration (FDA) estimates that 142,000 illnesses each year are caused by consuming eggs contaminated with Salmonella.
Among them is a final rule, issued by the FDA, to reduce the contamination in eggs. About 142,000 Americans are infected each year with Salmonella enteritidis from eggs, the result of an infected hen passing along the bacterium. About 30 die.
Eggs can be contaminated on the outer shell surface and internally. Internal contamination can be the result of penetration through the eggshell or by direct contamination of egg contents before oviposition, originating from infection of the reproductive organs. Once inside the egg, the bacteria need to cope with antimicrobial factors in the albumen and vitelline membrane before migration to the yolk can occur
Salmonella enteritidis can contaminate the contents of clean, intact shell eggs as a result of infections of the reproductive tissue of laying hens. The principal site of infection appears to be the upper oviduct. In egg contents, the most important contamination sites are the outside of the vitelline membrane or the albumen surrounding it. In fresh eggs, only a few salmonellae are present. As albumen is an iron-restricted environment, growth only occurs with storage-related changes to vitelline membrane permeability, which allows salmonellae to invade yolk contents.
Normally, the oviduct of the hen is sterile and therefore the shell and internal contents of the egg are also free of microorganisms (10,16). In some instances, however, the ovaries and oviduct may be infected with Salmonella and these may be deposited inside the egg (12). More frequently, however, the egg becomes contaminated after it is laid.
when hens were artificially infected to test for transmission rate to yolks: "Mature laying hens were inoculated intravenously with 106 colony-forming units of Salmonella enteritidis, Salmonella typhimurium, Salmonella infantis, Salmonella hadar, Salmonella heidelberg, or Salmonella montevideo to cause the systemic infection. Salmonella Enteritidis was recovered from three yolks of the laid eggs (7.0%), suggesting egg contamination from the transovarian transmission of S. enteritidis."
In this study, egg yolks were infected at the surface of the yolk (vitelline membrane) to determine the percentage of yolk contamination (a measure used to determine egg contamination resistance, with numbers lower than 95% indicating increasing resistance): Overall, the frequency of penetration of Salmonella Enteritidis into the yolk contents of eggs from individual lines of hens ranged from 30 to 58% and the mean concentration of Salmonella Enteritidis in yolk contents after incubation ranged from 0.8 to 2.0 log10 cfu/mL.
The migration of the bacterium into the nutritionally rich yolk is constrained by the lysozyme loaded vitelline membrane, and would need warm enough storage conditions within days and weeks. The high concentration on of antibodies of the yolk does not inhibit the Salmonella multiplication. Only seldom does transovarian contamination of the developing eggs with S. enteritidis make this bacterium occur in laid eggs, because of the bactericidal efficacy of the antimicrobial peptides
Over 5700 hens eggs from 15 flocks naturally infected with Salmonella enteritidis were examined individually for the presence of the organism in either egg contents or on shells. Thirty-two eggs (0·6%) were positive in the contents. In the majority, levels of contamination were low.
when hens are artificially infected with unrealistically large doses (according to the author): In the present study, groups of laying hens were experimentally infected with large oral doses of Salmonella Heidelberg, Salmonella Enteritidis phage type 13a, or Salmonella Enteritidis phage type 14b. For all of these isolates, the overall frequency of ovarian colonization (34.0%) was significantly higher than the frequency of recovery from either the upper (22.9%) or lower (18.1%) regions of the oviduct. No significant differences were observed between the frequencies of Salmonella isolation from egg yolk and albumen (4.0% and 3.3%, respectively).
The 1984 Rajneeshee bioterror attack was the food poisoning of 751 individuals in The Dalles, Oregon, through the deliberate contamination of salad bars at ten local restaurants with Salmonella. A group of prominent followers of Bhagwan Shree Rajneesh (later known as Osho) led by Ma Anand Sheela had hoped to incapacitate the voting population of the city so that their own candidates would win the 1984 Wasco County elections. The incident was the first and single largest bioterrorist attack in United States history.Having previously gained political control of Antelope, Oregon, Rajneesh's followers, who were based in nearby Rajneeshpuram, sought election to two of the three seats on the Wasco County Circuit Court that were up for election in November 1984. Fearing they would not gain enough votes, some Rajneeshpuram officials decided to incapacitate voters in The Dalles, the largest population center in Wasco County. The chosen biological agent was Salmonella enterica Typhimurium, which was first delivered through glasses of water to two County Commissioners and then, on a larger scale, at salad bars and in salad dressing.
As a result of the attack, 751 people contracted salmonellosis, 45 of whom were hospitalized, but none died. Although an initial investigation by the Oregon Public Health Division and the Centers for Disease Control did not rule out deliberate contamination, the agents and contamination were only confirmed a year later. On February 28, 1985, Congressman James H. Weaver gave a speech in the United States House of Representatives in which he "accused the Rajneeshees of sprinkling Salmonella culture on salad bar ingredients in eight restaurants".At a press conference in September 1985, Rajneesh accused several of his followers of participation in this and other crimes, including an aborted plan in 1985 to assassinate a United States Attorney, and he asked state and federal authorities to investigate. Oregon Attorney General David B. Frohnmayer set up an interagency task force, composed of Oregon State Police and the Federal Bureau of Investigation, and executed search warrants in Rajneeshpuram. A sample of bacteria matching the contaminant that had sickened the town residents was found in a Rajneeshpuram medical laboratory. Two leading Rajneeshpuram officials were convicted on charges of attempted murder and served 29 months of 20-year sentences in a minimum-security federal prison.2008 United States salmonellosis outbreak
The 2008 United States salmonellosis outbreak was an outbreak of salmonellosis across multiple U.S. states due to Salmonella enterica serovar Saintpaul. Over the course of the outbreak, 1442 cases were identified across 43 U.S. states, the District of Columbia, and Canada. The U.S. Centers for Disease Control and Prevention (CDC) investigation determined that jalapeño peppers imported from Mexico as well as Serrano peppers were major sources of the outbreak. Tomatoes may have been a source as well. The outbreak lasted from April to August, 2008.2012 outbreak of Salmonella
In general, the United States alone experiences 1 million cases of salmonellosis per year. In Europe, although there are around 100,000 incidents of salmonellosis reported annually, there has been a steady decrease in cases over the past four years. The exact number of those infected is impossible to know as not all cases are reported. Of these reported cases, some can be classified as foodborne disease outbreaks by the Center for Disease Control and Prevention (CDC) if "two or more people get the same illness from the same contaminated food or drink" or zoonotic outbreaks if "two or more people get the same illness from the same pet or other animal". In 2012, the various strains or serotypes of the Salmonella bacteria, related to the outbreaks in the United States, infected over 1800 people and killed seven. In Europe, the European Centre for Disease Prevention and Control (ECDC) reported 91,034 cases of Salmonella infection with 65,317 cases related to the 2012 outbreaks. Of those 65,317 cases, there were 61 deaths.Salmonella bacteria can be found in almost any product or animal that has been exposed to fecal matter. These exposures can occur from crops grown from waste-based fertilizers or from food items handled by infected humans. Salmonellosis is an intestinal disease, meaning that the bacteria must be ingested and processed through the intestines in order for infection to occur. Thus, salmonellosis is commonly spread to humans through ingestion of contaminated food items. It can also be spread through contact with reptiles and birds, usually after the person handles the animal or its environment (without hand-washing immediately) and then touches their mouth or food items. Those infected usually develop symptoms anywhere from 12–72 hours after first contact with Salmonella bacteria, and most do not require serious medical attention. This salmonellosis displays itself in humans with fever, abdominal pain, nausea, and, most commonly, diarrhea for a period of up to 7 days. Those requiring hospitalization usually are dehydrated or have extreme diarrhea, which can turn deadly, especially if the salmonella bacteria reaches the bloodstream. The elderly, young children, and those with weakened immune systems are most at risk for developing salmonellosis and suffering severe reactions. The most common serotypes of Salmonella in the United States and Europe are Enteritidis and Typhimurium.2018 American salmonella outbreak
The 2018 American salmonella outbreak was an American disaster in which over 250 people were sickened by chicken salad contaminated with salmonella. Other outbreaks were confirmed with turkey identified as the cause.Bacillary dysentery
Bacillary dysentery is a type of dysentery, and is a severe form of shigellosis.
Bacillary dysentery is associated with species of bacteria from the Enterobacteriaceae family. The term is usually restricted to Shigella infections.Shigellosis is caused by one of several types of Shigella bacteria. Three species are associated with bacillary dysentery: Shigella sonnei, Shigella flexneri and Shigella dysenteriae. A study in China indicated that Shigella flexneri 2a was the most common serotype.Salmonellosis caused by Salmonella enterica (serovar Typhimurium) has also been described as a cause of bacillary dysentery, though this definition is less common. It is sometimes listed as an explicit differential diagnosis of bacillary dysentery, as opposed to a cause.Bacillary dysentery should not be confused with diarrhea caused by other bacterial infections. One characteristic of bacillary dysentery is blood in stool, which is the result of invasion of the mucosa by the pathogen.Chromobacteriosis infection
Chromobacteriosis infections are a cutaneous condition caused by chromobacteria characterized by fluctuating abscesses.Gammaproteobacteria
Gammaproteobacteria are a class of bacteria. Several medically, ecologically, and scientifically important groups of bacteria belong to this class. Like all Proteobacteria, the Gammaproteobacteria are Gram-negative.List of feline diseases
Feline disease are those infections or diseases that infect cats. Some of these cause symptoms, sickness or the death of the animal. Some of these are symptomatic in a cat but not in other cats. Some are opportunistic and tend to be more serious in cats that already have other sicknesses. Some of these can be treated and the animal can have a complete recovery. Others, like viral diseases, cannot be treated with antibiotics. This is because antibiotics are not effective against viruses.List of foodborne illness outbreaks in the United States
In 1999, an estimated 5,000 deaths, 325,000 hospitalizations and 76 million illnesses were caused by foodborne illnesses within the US. The Centers for Disease Control and Prevention began tracking outbreaks starting in the 1970s. By 2012, the figures were roughly 130,000 hospitalizations and 3,000 deaths.List of notifiable diseases
The following is a list of notifiable diseases arranged by country.Paratyphoid fever
Paratyphoid fever, also known simply as paratyphoid, is a bacterial infection caused by one of the three types of Salmonella enterica. Symptoms usually begin 6–30 days after exposure and are the same as those of typhoid fever. Often, a gradual onset of a high fever occurs over several days. Weakness, loss of appetite, and headaches also commonly occur. Some people develop a skin rash with rose-colored spots. Without treatment, symptoms may last weeks or months. Other people may carry the bacteria without being affected; however, they are still able to spread the disease to others. Both typhoid and paratyphoid are of similar severity. Paratyphoid and typhoid fever are types of enteric fever.Paratyphoid is caused by the bacterium Salmonella enterica of the serotypes Paratyphi A, Paratyphi B, or Paratyphi C growing in the intestines and blood. They are usually spread by eating or drinking food or water contaminated with the feces of an infected person. They may occur when a person who prepares food is infected. Risk factors include poor sanitation as is found among poor crowded populations. Occasionally, they may be transmitted by sex. Humans are the only animals infected. Diagnosis may be based on symptoms and confirmed by either culturing the bacteria or detecting the bacterial DNA in the blood, stool, or bone marrow. Culturing the bacteria can be difficult. Bone-marrow testing is the most accurate. Symptoms are similar to that of many other infectious diseases. Typhus is an unrelated disease.While no vaccine is available specifically for paratyphoid, the typhoid vaccine may provide some benefit. Prevention includes drinking clean water, better sanitation, and better handwashing. Treatment of the disease is with antibiotics such as azithromycin. Resistance to a number of other previously effective antibiotics is common.Paratyphoid affects about six million people a year. It is most common in parts of Asia and rare in the developed world. Most cases are due to Paratyphi A rather than Paratyphi B or C. In 2015, paratyphoid fever resulted in about 29,200 deaths, down from 63,000 deaths in 1990. The risk of death is between 10 and 15% without treatment, while with treatment, it may be less than 1%.Pasteurized eggs
Pasteurized eggs are eggs that have been pasteurized in order to reduce the risk of food-borne illness in dishes that are not cooked or are only lightly cooked. They may be sold as liquid egg products or pasteurized in the shell.Rickettsia africae
Rickettsia africae is a species of Rickettsia.
It can cause African tick-bite fever.Rose spots
Rose spots are red macules 2-4 millimeters in diameter occurring in patients with enteric fever (which includes typhoid and paratyphoid). These fevers occur following infection by Salmonella typhi and Salmonella paratyphi respectively. Rose spots may also occur following invasive non-typhoid salmonellosis.
Rose spots are bacterial emboli to the skin and occur in approximately 1/3 of cases of typhoid fever. They are one of the classic signs of untreated disease, but can also be seen in other illnesses as well including shigellosis and nontyphoidal salmonellosis. They appear as a rash between the seventh and twelfth day from the onset of symptoms. They occur in groups of five to ten lesions on the lower chest and upper abdomen, and they are more numerous following paratyphoid infection.
Rose spots typically last three to four days.Salmonella
Salmonella is a genus of rod-shaped (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two species of Salmonella are Salmonella enterica and Salmonella bongori. S. enterica is the type species and is further divided into six subspecies that include over 2,600 serotypes. Salmonella was named after Daniel Elmer Salmon (1850–1914), an American veterinary surgeon. Salmonella species are non-spore-forming, predominantly motile enterobacteria with cell diameters between about 0.7 and 1.5 µm, lengths from 2 to 5 µm, and peritrichous flagella (all around the cell body). They are chemotrophs, obtaining their energy from oxidation and reduction reactions using organic sources. They are also facultative aerobes, capable of generating ATP with oxygen ("aerobically") when it is available, or when oxygen is not available, using other electron acceptors or fermentation ("anaerobically"). S. enterica subspecies are found worldwide in all warm-blooded animals and in the environment. S. bongori is restricted to cold-blooded animals, particularly reptiles.Salmonella species are intracellular pathogens;
certain serotypes causing illness. Nontyphoidal serotypes can be transferred from animal-to-human and from human-to-human. They usually invade only the gastrointestinal tract and cause salmonellosis, the symptoms of which can be resolved without antibiotics. However, in sub-Saharan Africa, nontyphoidal Salmonella can be invasive and cause paratyphoid fever, which requires immediate treatment with antibiotics. Typhoidal serotypes can only be transferred from human-to-human, and can cause food-borne infection, typhoid fever, and paratyphoid fever. Typhoid fever is caused by Salmonella invading the bloodstream (the typhoidal form), or in addition spreads throughout the body, invades organs, and secretes endotoxins (the septic form). This can lead to life-threatening hypovolemic shock and septic shock, and requires intensive care including antibiotics.
The collapse of the Aztec society in Mesoamerica is linked to a catastrophic Salmonella outbreak, one of humanity's deadliest, that occurred after the Spanish conquest.Salmonella enterica
Salmonella enterica (formerly Salmonella choleraesuis) is a rod-shaped, flagellate, facultative aerobic, Gram-negative bacterium and a species of the genus Salmonella. A number of its serovars are serious human pathogens.Salmonellosis in the United States
Salmonellosis annually causes, per CDC estimation, about 1.2 million illnesses, 23,000 hospitalizations, and 450 deaths in the United States every year.The shell of the egg may be contaminated with Salmonella by feces or environment, or its interior (yolk) may be contaminated by penetration of the bacteria through the porous shell or from a hen whose infected ovaries contaminate the egg during egg formation.Serratia infection
Serratia infection refers to a disease caused by a species in the genus Serratia.
The species involved is usually Serratia marcescens.
It can cause nosocomial infections.Zoonosis
Zoonoses (also known as zoonosis and as zoonotic diseases) are infectious diseases caused by bacteria, viruses and parasites that spread between animals (usually vertebrates) and humans.Major modern diseases such as Ebola virus disease and salmonellosis are zoonoses. HIV was a zoonotic disease transmitted to humans in the early part of the 20th century, though it has now mutated to a separate human-only disease. Most strains of influenza that infect humans are human diseases, although many strains of swine and bird flu are zoonoses; these viruses occasionally recombine with human strains of the flu and can cause pandemics such as the 1918 Spanish flu or the 2009 swine flu. Taenia solium infection is one of the neglected tropical diseases with public health and veterinary concern in endemic regions. Zoonoses can be caused by a range of disease pathogens such as viruses, bacteria, fungi and parasites; of 1,415 pathogens known to infect humans, 61% were zoonotic. Most human diseases originated in animals; however, only diseases that routinely involve animal to human transmission, like rabies, are considered direct zoonosis.Zoonoses have different modes of transmission. In direct zoonosis the disease is directly transmitted from animals to humans through media such as air (influenza) or through bites and saliva (rabies). In contrast, transmission can also occur via an intermediate species (referred to as a vector), which carry the disease pathogen without getting infected. When humans infect animals, it is called reverse zoonosis or anthroponosis. The term is from Greek: ζῷον zoon "animal" and νόσος nosos "sickness".