LOS ANGELES — Health officials on Friday reported a typhus outbreak in Los Angeles County and say it has reached "epidemic levels" in the city of Pasadena.

Twenty cases have been reported in Pasadena, mostly in the last two months, health officials told NBC News, noting that a normal year would typically only see five infections. The city of Long Beach, California, has 12 cases so far in 2018 — double the normal annual number, said Emily Holman, the city's infectious disease response coordinator.

The number of cases in the rest of the county since July is nine, which counts as an "outbreak," Los Angeles County Department of Public Health officials said in a statement. Pasadena and Long Beach have their own health departments even though they exist within the county.

“The Pasadena Public Health Department is reporting epidemic levels of typhus fever this year," read a statement from that city on Friday.

The official source of the outbreak is said to be fleas from domestic and wild animals.

"Infection happens when the feces from infected fleas are rubbed into cuts or scrapes in the skin or rubbed into the eyes," the county health department states on its website.

Some experts, however, say the true culprit is the inhumane conditions the county's expanding homeless population lives in.

"All of the cases have a history of living or working in the downtown Los Angeles area," a county health spokeswoman said via email.

Andy Bales, the CEO of the Union Rescue Mission, which has nearly 1,400 beds for those fleeing or avoiding downtown's Dickensian streets, said, "The conditions on Skid Row are ripe for even more serious issues than this."

In 2014, Bales had a leg amputated after he was exposed to flesh-eating bacteria downtown.

The office of Mayor Eric Garcetti said it is on the case.

"We're deploying every available resource to help control and stop this outbreak," mayoral spokesman Alex Comisar said via email. "The City and County have formed a dedicated task force through our Unified Homelessness Response Center to keep Angelenos safe, and ensure everyone gets the treatment they need as quickly as possible."

A dog flea. Kim Taylor / Nature Picture Library/Getty Images

Typhus or typhus fever is a flea-borne infectious disease that can cause high fever, headache, chills, and body aches, rashes and in rare cases, meningitis and death. (It is not the same as typhoid fever, which is caused by a different kind of bacteria and is usually spread by consuming contaminated food and water.)

Health officials in Pasadena are blaming the outbreak on a warm summer and fall and human interaction with animals in neighborhoods that have an "interface" with wildlife in canyons and the Angeles National Forest. They say the disease has nothing to do with homelessness in their high-income city.

The Los Angeles County Department of Public Health spokeswoman said via email that officials are investigating the source of the typhus in downtown L.A. by searching specifically for "high concentrations of infected fleas and/or infected rats, feral cats and opossums."

Bales noted, "There are lots of rats on Skid Row, and there are lots of dogs that belong to homeless people."

In September the nonprofit research organization Economic Roundtable released an analysis that concluded the county has 102,955 homeless people — nearly double what government officials had previously reported.

"The numbers on the sidewalk have increased dramatically," said Alice Callaghan, founder of the Skid Row services organization Las Familias del Pueblo. "They're like refugee camps."