outbreak can help determine appropriate future choices. other antibiotics proven to be effective include cotrimoxazole, erythromycin, tetracycline, chloramphenicol, and furazolidone. fluoroquinolones, such as ciprofloxacin, also may be used, but resistance has been reported. antibiotics improve outcomes in those who are both severely and not severely dehydrated. azithromycin and tetracycline may work better than doxycycline or ciprofloxacin. zinc supplementation in bangladesh zinc supplementation reduced the duration and severity of diarrhea in children with cholera when given with antibiotics and rehydration therapy as needed. it reduced the length of disease by eight hours and the amount of diarrhea stool by 10%. supplementation appears to be also effective in both treating and preventing infectious diarrhea due to other causes among children in the developing world. prognosis if people with cholera are treated quickly and properly, the mortality rate is less than 1%; however, with untreated cholera, the mortality rate rises to 50–60%. for certain genetic strains of cholera, such as the one present during the 2010 epidemic in haiti and the 2004 outbreak in india, death can occur within two hours of becoming ill. epidemiology cholera affects an estimated 2.8 million people worldwide, and causes approximately 95,000 deaths a year (uncertainty range: 21,000–143,000) as of 2015. this occurs mainly in the developing world. in the early 1980s, death rates are believed to have still been higher than three million a year. it is difficult to calculate exact numbers of cases, as many go unreported due to concerns that an outbreak may have a negative impact on the tourism of a country. as of 2004, cholera remained both epidemic and endemic in many areas of the world. recent major outbreaks are the 2010s haiti cholera outbreak and the 2016–2021 yemen cholera outbreak. in october 2016, an outbreak of cholera began in war-ravaged yemen. who called it "the worst cholera outbreak in the world". in 2019, 93% of the reported 923,037 cholera cases were from yemen (with 1911 deaths reported). between september 2019 and september 2020, a global total of over 450,000 cases and over 900 deaths was reported; however, the accuracy of these numbers suffer from over-reporting from countries that report suspected cases (and not laboratory confirmed cases), as well as under-reporting from countries that do not report official cases (such as bangladesh, india and philippines). although much is known about the mechanisms behind the spread of cholera, researchers still do not have a full understanding of what makes cholera outbreaks happen in some places and not others. lack of treatment of human feces and lack of treatment of drinking water greatly facilitate its spread. bodies of water have been found to serve as a reservoir of infection, and seafood shipped long distances can spread the disease. cholera had disappeared from the americas for most of the 20th century, but it reappeared toward the end of that century, beginning with a severe outbreak in peru. this was followed by the 2010s haiti cholera outbreak and another outbreak of cholera in haiti amid the 2018–2023 haitian crisis. as of august 2021 the disease is endemic in africa and some areas of eastern and western asia (bangladesh, india and yemen). cholera is not endemic in europe; all reported cases had a travel history to endemic areas. history of outbreaks