Plague

Plague is a bacterial disease of rodents (and sometimes rabbits) that is transmitted from rodent to rodent through the bites of infected fleas. Any rodents such as mice, squirrels, pack rats, prairie dogs, and chipmunks may be infected with plague, but the one rodent most commonly infected in this area is the rock squirrel. Rodents generally die from the infection. Humans may become infected through the bites of infected fleas or through direct contact with infected rodent tissues. Direct contact cases usually involve hunters who field dress infected squirrels without wearing gloves, allowing plague bacteria to enter the body through open cuts or abrasions in the skin. Pets, particularly cats and occasionally dogs, may acquire infections through the bites of infected fleas or through ingesting infected rodent tissues. In Bernalillo County plague has historically been found in the East Mountain area and the Western Foothills of the Sandia Mountains. Plague can be found year-round but is most likely to occur during April-November when rodents are more active.

Clinical Forms of Plague & Symptoms

Plague infection in humans may produce the following clinical forms and associated symptoms. Humans generally start with Bubonic plague and can progress to Septicemic and Pneumonic if untreated. In some cases the first sign of the disease may begin with Septicemic or Pneumonic plague. All three forms are caused by the same bacteria. The forms are used to describe the course of the infection in the human body. The only form that can be spread person to person is the Pneumonic form. Plague is treatable with antibiotics.

Bubonic plague-This is generally the most common form and is acquired through the bites of infected fleas or by direct contact with infected tissues. Symptoms appear after a two to six day incubation period and include a rapid onset of high fever, swollen lymph nodes (called bubos) in the neck, armpit or groin areas, headache, and fatigue.

Septicemic plague-If Bubonic plague is untreated the disease can progress to Septicemic Plague which is a toxic poisoning of the blood stream. Some patients, usually teenagers, may start with the Septicemic form of plague due to flea bites or direct contact with infected tissues and have no swollen lymph nodes (bubos). Symptoms include high fever, lethargy, and mental confusion.

Pneumonic plague-If Bubonic or Septicemic plague are untreated the disease may progress to Pneumonic plague. In this form the plague bacteria invade the lung tissue. Humans may also acquire Pneumonic plague by inhaling infective droplets from another Pneumonic patient or cat. Symptoms include lung congestion, difficulty in breathing, high fever, chest pain and coughing with bloody discharge. This is the only form that is transmittable from person to person.

Control Strategies

Integrated Vector Management staff conduct routine surveillance throughout the year to detect the presence of plague in the East Mountains and Western Foothills. Surveillance consists of capturing live rodents to collect blood/flea samples for plague analysis. These samples are sent to the Centers for Disease Control in Ft. Collins, CO for analysis. Integrated Vector Management staff also are involved in dead rodent retrieval in these same areas. If wild rodents have died for no apparent reason, Integrated Vector Management staff will retrieve the animals and take a tissue sample to the State Laboratory Division in Albuquerque and the tissue will be tested for plague. If plague is detected in an area, especially if a person or a domestic pet is involved, we will implement follow-up surveillance, flea control strategies, i.e., applying an insecticide with low toxicity to humans and animals to kill potentially infected fleas, and educational outreach. Educational outreach includes literature distribution and community presentations on the prevention and control of plague.

Your Health

Integrated Vector Management staff are involved in preventing/reducing the incidence of plague in the community. Plague can become a serious problem in humans or pets if left untreated, but if the proper precautions are implemented it can be prevented. Plague can also adversely affect domestic pets, especially cats. Infected cats can readily transmit plague to its owners. Integrated Vector Management strategies are implemented in plague control such as reducing rodent harborage, intensive surveillance, utilizing safe pesticides if necessary, and community education.

Our Environment

Integrated Vector Management strategies such as surveillance help to pinpoint areas where control is necessary and this helps to reduce the use of insecticides unnecessarily. This reduces the overall usage of insecticides in the environment.