SANTA FE - Several cases of plague among dogs and cats around New Mexico has public health officials urging people to be wary of a possible spread to humans.

New Mexico hasn't had any human cases of plague or hantavirus so far this year, but plague cases in pets can serve as a warning that human cases might follow, public health veterinarian Dr. Paul Ettestad said.

The wet winter and spring can mean growing rodent populations, increasing people's risk of becoming ill from the diseases rodents carry, Ettestad said.

Plague is a bacterial disease of rodents generally transmitted to humans through the bites of infected fleas. It also can be transmitted by direct contact with infected animals, including pets.

Symptoms in humans include sudden onset of fever, chills, headache, and weakness. In most cases there also is a painful swelling of the lymph node in the groin, armpit or neck areas. Prompt diagnosis and antibiotics can greatly reduce the fatality rate.

The Health Department recommends seeing a doctor about any unexplained illness involving a sudden and severe fever.

The agency recommends avoiding sick or dead rodents and rabbits and their nests and burrows; cleaning up areas near homes where rodents could live; and cleaning up nests and droppings with disinfectant. People also should air out closed up buildings before entering.

The state Department of Health's Scientific Laboratory has confirmed plague in a dog near San Jon in Quay County. Other

confirmed cases for 2010 include a dog and cat in the city of Santa Fe and the rural Santa Fe County subdivision of Eldorado and a dog and cat from the Alcalde and Abiquiu areas in Rio Arriba County.

New Mexico had six human plague cases last year, including one in which an 8-year-old Santa Fe County boy died.

Hantavirus also is transmitted by rodents - especially the deer mouse - through their urine, droppings or saliva. People can contract the disease by breathing in the aerosolized virus.

Early symptoms are fever and muscle aches, possibly with chills, headache, nausea, vomiting, diarrhea, abdominal pain and cough.

The state had four hantavirus cases in 2009, none of them fatal. It had two cases in 2008, both of them fatal.