Atlanta: Cases of cyclosporiasis -- a parasitic intestinal infection -- have surpassed 18,000 across 45 states, according to updated figures released Wednesday by the US Centers for Disease Control and Prevention (CDC).

According to Anadolu Agency, since May 1, the CDC has confirmed 6,707 cases of the gastrointestinal illness through laboratory testing, including 423 people who required hospitalization. The agency is also tracking more than 11,500 additional suspected cases that have not yet been confirmed through laboratory testing or are still under investigation.

A large share of the cases come from Michigan and Ohio, where many infections have been linked to recalled iceberg lettuce. The CDC noted that cyclosporiasis cases typically increase during the summer months, meaning additional cases in other states could be associated with different sources.

It also explained that confirming whether a case should be included in the national count can take up to six weeks. Patients ranged in age from 1 to 98 years old, and no deaths have been reported. Investigators have linked some infections to shredded iceberg lettuce served at certain Taco Bell restaurants in nine states.

However, the CDC said it is continuing to investigate other possible sources of the outbreak. The lettuce supplied to Taco Bell came from Taylor Farms and was sourced from central Mexico. Earlier this month, Taylor Farms de Mexico voluntarily recalled its iceberg lettuce from central Mexico, affecting products distributed across 27 states.