Cumberland County continues to dominate the list of ZIP codes in Maine reporting the highest rates of COVID-19 infection, with a handful of towns in York and Androscoggin counties rounding out the top 10.

But as Maine experiences a worrying spike in coronavirus cases, public health officials are warning that new infections are occurring throughout the state, including in rural towns that previously had few to no cases.

Dr. Nirav Shah, director of the Maine Center for Disease Control and Prevention, has described the situation as “sustained, forceful and widespread community transmission” across the state.

New ZIP code-level data released this week by the Maine CDC show that, not surprisingly, some of Maine’s most densely populated neighborhoods have the highest total COVID-19 cases since the virus’s detection in Maine in mid-March. Lewiston’s 04240 ZIP code has had the most total cases, with 453, followed by Portland’s 04103 and 04101 ZIP codes with 383 and 324 cases, respectively. Those figures represent total cases to date, including individuals who have recovered from the disease.

ZIP codes in Westbrook, South Portland, Falmouth, Biddeford, Scarborough and Auburn round out the top 10 in total COVID-19 cases.

Examining the ZIP code data on a per capita basis produces similar results, but with a few midsized towns in York County – such as Alfred, Springvale and Sanford – jumping higher on the list because of outbreaks or community transmission. But it is impossible to calculate per capita rates for every town in the state because the Maine CDC has only released specific case numbers for 113 ZIP codes, plus an additional 115 areas that have had zero COVID-19 cases.

Case numbers for the remaining 168 ZIP codes are provided in ranges – between one to five cases, six to 19 cases, and 20 to 49 cases – because “exact case counts are suppressed in all ZIP codes with 5 or fewer cases or a population less than 2,000,” the agency said.

The Portland ZIP code of 04101, which includes downtown, the East End and Bayside, has had the highest prevalence of the virus with one case occurring among every 58 residents. The area also had the highest prevalence in June when the Maine CDC first began releasing ZIP code-level data.

Taken together, the three ZIP codes in Maine’s largest city – 04101, 04102 and 04013 – account for 938, or nearly 15 percent, of the state’s 6,467 COVID-19 cases since March. But the virus is less prevalent among Portland’s population on a per capita basis, affecting one person out of every 74 residents compared to one among every 67 Falmouth residents and one of every 71 Westbrook residents, based on the ZIP code data.

Cape Elizabeth had a rate of 1 case for every 96 residents while Lewiston stands at 1 case for every 82 residents.

The three York County towns in the top 10 have also been impacted by outbreaks since the summer, some of which were epidemiologically linked to an August wedding and reception roughly 200 miles away in Millinocket. Alfred, which experienced an outbreak at the York County Jail that sickened roughly 70 inmates or staff, had a rate of 1 case for every 84 residents, while Springvale and Sanford have rates of one case for every 100 and 101 residents of their ZIP codes, respectively.

Determining per capita rates for smaller towns – including some that have been impacted by outbreaks – is more difficult or imprecise because the Maine CDC does not report exact case numbers for ZIP codes with fewer than 2,000 residents.

For instance, in the rural Waldo County town of Brooks, at the center of a growing outbreak tied to a church, there have been between 20 and 49 COVID-19 cases in a ZIP code with just 1,727 residents. That means the lowest rate would be 1 case for every 86 residents of Brooks, but it could be as prevalent as occurring once for every 35 residents. The Penobscot County town of East Millinocket, which was impacted by the August outbreak tied to a wedding, had a similar range.

Shah, the Maine CDC director, urged Mainers against using ZIP code case numbers to make decisions about how vigilant to be regarding precautions against COVID-19.

“What we’ve seen in the past week, in the past month and certainly today is that the virus is in every single corner of the state – every ZIP code, every county,” Shah said on Wednesday. “So while the ZIP code data are interesting and informative, they are not a tool for individuals to calculate the risk of engaging in certain activities. We should be going about our days as we have recommended for months, which is that the virus is everywhere around us.”

After successfully avoiding the surges playing out in other states in recent months, Maine is now seeing some of the highest daily infection numbers since the pandemic began. On Wednesday, the state logged 76 additional cases followed by 80 more on Thursday and 103 on Friday. That increased the state’s seven-day daily average of new cases to 67.9 on Friday, more than double the number from one month earlier and up from 34.9 a week ago.

Rural Somerset County accounted for 26 new cases in two days, a sharp increase in a county that had previously seen less than 150 cases in seven months.

“What’s important and concerning in Somerset County is there is no new outbreak investigation in any facility in that county, let alone one that accounts for the increase of 26 cases in two days,” Shah said during his Thursday briefing. “To put that differently, based on what we know right now, this is strong evidence of community transmission all throughout Somerset County.”