Salmonella species are frequent human pathogens. An incredibly diverse genus, different types of Salmonella infect an enormous variety of species, from mammals to fish to invertebrates. They are typically acquired via ingestion of contaminated food or water, and the bacteria then seed the intestine and replicate there. These gram-negative organisms are the cause of typhoid fever (Salmonella enterica serovar typhi) and can also cause acute gastroenteritis (multiple types, including Salmonella enterica serovars enteritidis and typhimurium).
Of these types, S. typhi is the most deadly, and generally the best known. Typhoid fever, while no longer common in developed countries, is still a significant burden in developing areas, where ingestion of S. typhi leads quickly to fever, nausea, and vomiting. The bacterium can also spread from the intestine to the blood and other organs, causing a systemic infection that can rapidly be fatal. Here in the U.S., however, S. enteritis and S. typhimurium are more common–indeed, they rank among the most common food-borne pathogens here. These bacteria also are ingested and cause gastrointestinal symptoms, but disease is typically more mild than with S. typhi. The victim becomes symptomatic ~12-48 hours after ingestion of the bacteria, experiencing vomiting, nausea, abdominal cramping, and diarrhea. The illness can last from 3-7 days in healthy individuals; in the very young or old or those with other types of compromised immune systems, symptoms may be prolonged and more severe, and more frequently result in death.
There has been much work over the past 50 years examining factors that allow Salmonella to cause disease, and to characterize the bacterium’s interaction with its hosts. However, a novel study takes this research to another level, quite literally–looking at how space travel affects the virulence of Salmonella typhimurium in a mouse model of disease. More after the jump…
Continue reading “Germs….in…..SPACE!”