Health officials say a drug-resistant mutant super-strain of a nasty stomach bug has made its way into the U.S. and is spreading - already causing more than 200 illnesses since last May. Shigella infections, otherwise known as 'Delhi Belly' or 'Montezuma's revenge' were traced to people who had recently traveled to the Dominican Republic, India or other countries. The symptoms include diarrhea, stomach cramps and nausea. Outbreaks of the Shigella bacteria are not unusual, but this strain is resistant to the antibiotic most commonly prescribed for adults. Cases of shigellosis (bacteria pictured), otherwise known as 'Delhi Belly' or 'Montezuma's revenge' were traced to people who had recently traveled to the Dominican Republic, India or other countries . The Centers for Disease Control and Prevention released the report Thursday. The superbug sickened at least 243 people, in 32 states and Puerto Rico. Sometimes antibiotics are prescribed, especially for more serious cases. CDC Director Tom Frieden said in a statement: 'These outbreaks show a troubling trend in Shigella infections in the United States. 'Drug-resistant infections are harder to treat and because Shigella spreads so easily between people, the potential for more – and larger – outbreaks is a real concern. 'We’re moving quickly to implement a national strategy to curb antibiotic resistance because we can’t take for granted that we’ll always have the drugs we need to fight common infections. Scientists  unlocked the genetic code of bacteria grown from a soldier who died of dysentery in World War I. Their findings revealed a superbug already resistant to penicillin and other antibiotics decades before they were in common use. CDC Director Tom Frieden said the spike in outbreaks show a 'troubling trend' in Shigella infections across the United States . Kate Baker of Britain's Wellcome Trust Sanger Institute said last November that analysis of genetic differences between this 1915 sample of Shigella flexneri and three others isolated in 1954, 1984 and 2002 showed that while the bacterium has changed relatively little, the mutations it has acquired have made it more dangerous and persistent. It also went though what is known as a 'serotype conversion', she said, which made it able to re-infect and cause illness in people who had already been infected before and would previously have been immune to further attacks. Shigella causes an estimated 500,000 cases of diarrhea in the United States every year. CDC and public health partners investigated several recent clusters of shigellosis in Massachusetts, California and Pennsylvania and found that nearly 90 percent of the cases tested were resistant to ciprofloxacin (Cipro), the first choice to treat shigellosis among adults in the United States.
Cases have been traced to ill travelers from India and Dominican Republic.
Symptoms include diarrhea, stomach cramps and nausea.
Sometimes antibiotics are prescribed for more serious cases.
However strain has become increasingly resistant to drugs.