|When rodents are present in a house, there may also be rat fleas.|
The oriental rat flea is thought to be the principal vector of
murine typhus, a disease on the rise in Texas. (Image courtesy
Pest and Diseases Image Library, Bugwood.org)
The causative agent for murine typhus (the term "murine" is a scientific term referring to rodents) is a rickettsial parasite called Rickettsia typhi. This parasite is always present in rodent populations, both Norway and roof rats, and to a lesser extent mice and opossums. The primary vector that transmits the parasite from rodent to rodent, and occasionally to humans, is the oriental rat flea, Xenopsylla cheopis, though other fleas, including the cat flea are suspected to be occasional vectors.
Symptoms of murine typhus include fever, headache and rash. Left untreated, the disease can be fatal in about 2% of cases; but once diagnosed, typhus is easily treated. Numbers of cases peak during the summer months of June and July, but in south Texas there is a secondary peak in cases during the winter.
The typhus pathogen is thought to infect people when they scratch an itchy flea bite. It is present in the flea's feces, which may be rubbed into the site of the bite during scratching.
While the exact cause for the increase in typhus cases is unknown, pest control will play an important role in any solution. Experience with murine typhus in the past has shown that cases peak when flea numbers are highest, and that case frequency declines when rats are controlled, and insecticides applied for fleas.
In 54% of the cases reported in this study, fleas were reported to be present in the home, and 34% of patients recalled a flea bite. Rodents were known to be present by the victims in about 29% of the cases, and some form of other wildlife was present in 42% of cases.
Good flea control, rodent exclusion and rodent control are among the most important public health services our industry provides. So if you didn't have enough reasons to explain to customers why they need you, you now have one more.