Medford's city government deserves credit for taking on the "zombie house" issue that has plagued many cities in the wake of the Great Recession. It should not rest on its laurels, but rather use its initial success as motivation to actively clean up problem properties elsewhere in the city.

The City Council heard last week that after five derelict properties were threatened with receivership in March, action was taken to improve or demolish the structures. Four of the homes will be either demolished or repaired and the fifth has gone into foreclosure.

Relying on a state law, the City Council in December approved a series of ordinances that give the city the authority to foreclose on properties with building or housing code violations that threaten "the public health, safety, or welfare" and whose owners have not "acted in a timely manner to correct the violations."

The ordinance was meant to zero in on so-called "zombie houses," which earned their name because while they are usually uninhabited — and often uninhabitable — their owners take no action to bring them back to a useful condition. They are the living dead of homes.

Owner-occupants of a dilapidated home can be fined and risk losing the roofs over their heads. But zombie houses are typically owned either by absentee landlords or lending institutions.

Those institutions, whether mortgage companies or banks, are sometimes engaged in an insidious practice in which they foreclose on a property, but do not offer it for sale, instead collecting on a mortgage insurance policy while keeping the property as an asset. They can collect on the insurance for years and then, when that source is milked dry, sell the property. In the meantime, the surrounding neighbors often have to live with an unkempt, and at times dangerous, home in their midst.

One of the five properties identified by Medford as "the worst of the worst," a home on Midway Road, is a prime example. It was the subject of 192 calls to the police for various eyesores and illegal activities, including drug dealing and transient camping.

Another, on Central Avenue at its intersection with Court Street, has been a blight on one of the city's main thoroughfares for decades. Councilor Kay Brooks noted that she sees the house — complete with boarded-up windows — on a daily basis, as she lives only a block away. She is joined by thousands of motorists every day, many of whom have no doubt become inured to the sight.

Now that the owners of the "worst of the worst" have been called on the carpet, the city should quickly move on to the "next worst." Their violations may not quite stack up to those of the awful five, but they remain eyesores and detriments to their neighborhood and to the city at large. Good job, city officials, now keep it up.