Western CDC laboratory reorients its wild rodent plague investigations

The U. S. Public Health Service has been concerned with wild rodent plague since 1908 when ground squirrels (Citellus beecheyi) were first found plague-infected in Contra Costa County, Calif. Previous to this time, it was thought that a ll plague in the United States was a domestic rat disease from which human cases were derived. As long as the reservoir of this disease was rats and rats only, it could be eliminated by effective rat control measures in the few California cities on the San Francisco Bay and in Seattle, Wash., where it was known to occur. The demonstration of the infection in ground squirrels indicated that there might be a rural reservoir complementing that produced by rats in ities. The possibility of eliminating plague through reduction or elimination of the reservoir depended on the geographic extent of the infection in ground squirrels.195