Samantha Nelson

USA TODAY

Authorities in Indiana and Ohio are on high alert after a supercharged form of heroin is suspected of causing 50 overdoses in the two states since Tuesday and more than 75 total since Friday.

Cincinnati saw a spike in overdoses over the weekend when the Hamilton County Heroin Coalition reported more than 30 overdoses Monday. Since Tuesday, 33 more people have overdosed in Cincinnati, including three fatal overdoses.

In Jennings County, Ind., officials responded to 14 overdoses late Tuesday and early Wednesday, according to the Jennings County Sheriff's Department and Seymour Police. One was fatal.

Authorities are investigating to see if a specific source of heroin was tainted or cut with something that caused the users to overdose.

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Law enforcement officials suspect the heroin was laced with fentanyl, a powerful synthetic opioid painkiller used to treat patients recovering after surgery. According to the Drug Enforcement Administration, fentanyl is 50 times more powerful than heroin.

Some of the people who overdosed in Jennings County required multiple doses of naloxone to reverse the effects of the opiate, Craig Hayes, assistant chief of the Seymour, Ind., Police Department told The Indianapolis Star. Police, who still are waiting on lab results, believe that the drug was heroin combined with either fentanyl or a similar but even more powerful drug called carfentanil, which is intended as a sedative in elephants and other large animals.

Combining drugs like fentanyl and carfentanil with heroin gives users a more intense high but also increases the chances of death. In cases of overdoses of heroin laced with these drugs, multiple doses of naloxone often are required.

"Please spread the word," Seymour Police warned in a Facebook post Tuesday. "If you know anyone that may come in contact with this heroin, please warn them!!! You may save their life!!"

A similar cluster of overdoses occurred Aug. 15 in Huntington, W.Va., where 27 people overdosed within five hours, one fatally. The number of calls exhausted emergency service resources, according to officials.

A batch of heroin, which authorities said potentially contained something stronger, also was blamed for the overdoses. Emergency medical personnel had to administer naloxone three times to one person.

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Police Chief Tom Synan of Newtown, Ohio, who heads the Hamilton County Heroin Coalition, told The Cincinnati Enquirer that Cincinnati's spike is similar to the overdoses a few weeks ago in the Ohio cities of Akron and Columbus, when carfentanil was identified in the heroin. Law enforcement also found evidence of carfentanil being used in the Cincinnati area, but Synan said it's too soon to know the exact cause of Cincinnati's most recent spate of overdoses.

"We have no idea, really, what's causing this at this point, if it's carfentanil, fentanyl or something else in this particular batch of heroin,” Synan said.

Police Chief Joe Ciccarelli in Huntington noted that his city also has had cases where heroin was contaminated with drugs such fentanyl.

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Drug overdose is now the leading cause of accidental death in the United States. Between 2002 and 2013, the rate of heroin-related deaths nearly quadrupled, according to the federal Centers for Disease Control and Prevention.

In 2014, West Virginia had the highest rate of overdose deaths in the nation at 35.5 deaths per 100,000 people, according to the CDC.

Ohio's rate was the fifth highest at 24.6 deaths, and Kentucky, which borders Ohio and Indiana, was the fourth highest at 24.7 deaths. Indiana was ranked 16th at 18.2 deaths per 100,000.

Contributing: Cameron Knight, Terry DeMio and Patrick Brennan, The Cincinnati Enquirer; Vic Ryckaert and Shari Rudavsky, The Indianapolis Star; Justin Sayers, The (Louisville) Courier-Journal. Follow Samantha Nelson on Twitter: @samm1son