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CNN —  

The Philadelphia Department of Health has declared a public health emergency due to a surge in Hepatitis A, Dr. Thomas A. Farley, Health Commissioner of the City, said Thursday.

So far this year, 154 people have tested positive for the highly contagious liver disease, with 85% of diagnoses occurring since May, the department said. Typically, the city sees between two and nine cases each year.

Preliminary information indicates 67% of people who have been diagnosed with Hepatitis A say they have used drugs, while 26% report homelessness, according to health officials. All but four of the confirmed cases have occurred in adults.

“While there’s not an exact cause that we can pinpoint, Philadelphia had been in the grip of the opioid crisis, which the Health Commissioner had called the worst epidemic here in more than a century,” James Garrow, spokesman for Philadelphia Department of Public Health, told CNN in an email.

Garrow said the bulk of cases have occurred among at-risk populations in the northern neighborhood of Kensington.

“We’ve seen, in other cities, similar outbreaks tied to homelessness and illicit drug use so believe this outbreak is the same,” he added. “There hasn’t been a specific change, just a bad situation that has been going for a while.”

Viral symptoms

Caused by a virus, Hepatitis A is an infection that people pick up either by coming into contact with human waste or by consuming contaminated food or water. Unwashed hands and unsanitary conditions help spread the disease.

Fever, tiredness, loss of appetite, nausea, stomach pain, vomiting, joint pain and jaundice (yellow skin or eyes and dark urine) are symptoms, according to the US Centers for Disease Control and Prevention. Symptoms usually appear two to six weeks after infection and last less than two months.

Southern New Jersey and suburban Pennsylvania counties around Philadelphia are also reporting higher than usual numbers of Hepatitis A among the same at-risk populations, according to the city’s health department.

The Hepatitis A vaccine requires two doses given at least six months apart for long-lasting protection, according to the CDC. Since last summer, 12,439 vaccinations have been dispensed to adults in Philadelphia. The city has distributed more than 4,000 personal hygiene items, including hand sanitizer, soap, tissue packets and condoms, to at-risk populations.

“Despite these aggressive and extensive efforts, Hepatitis A virus is spreading rapidly and is expected to continue doing so, thereby necessitating further action… and expanded resources to control this epidemic,” wrote Farley.

In response to the emergency, Philadelphia will offer free vaccinations for at-risk populations including the homeless, drug users, people recently incarcerated, men who have sex with men, and people with chronic liver disease, Farley said. Close contacts of those who are infected will also be eligible.

Context for the crisis

The 2017 Hepatitis A epidemic in San Diego County, California, included 592 infections, primarily among the homeless and illegal drug users. Twenty people died, wrote Farley in his statement. The California epidemic was controlled by increased vaccination and improved sanitation, Farley said.

Based on its annual “Point in Time” count, Philadelphia has experienced rising rates of homelessness over the past few years, according to CNN affiliate KYW. The year 2017 saw a 36% increase over the prior year, followed by a 13% jump in 2018. This year’s increase was 5%.

Meanwhile, illicit drug use rates, which can be difficult to gauge, may also be rising. Almost half of people admitted to treatment reported using heroin as their primary drug. That is a 26% increase from 2016, according to one recent government report.