A 12-year-old boy developed fever to 38.9ºC and felt ill. Over the next 2 days, he developed a red spots on his hands and arms, which became petechial (Figure 188-1) and spread to involve his entire upper extremities and trunk. He also developed abdominal pain and a headache. History was significant for a recent camping trip with his family to the Southeastern coast of the US. The parents report that he did sustain several tick bites while camping. He was treated presumptively for Rocky Mountain Spotted Fever (RMSF) with doxycycline, and his symptoms resolved over several days.
Petechial rash characteristic of late Rocky Mountain Spotted Fever (RMSF). (Used with permission from Johanna Goldfarb, MD.)
Zoonoses are infectious agents spread to humans by animals. Infection may occur through direct contact with the animal or via vectors such as ticks (Table 188-1). Examples of zoonotic diseases include RMSF, Ehrlichiosis, Tularemia, Cat-scratch disease, and Rat-bite fever.
TABLE 188-1Epidemiologic Characteristics of Selected Zoonoses ||Download (.pdf) TABLE 188-1 Epidemiologic Characteristics of Selected Zoonoses
|Disease ||Infectious Agent ||Seasonality ||Reservoir ||Vector/Exposure ||Risk Area |
|RMSF ||Rickettsia rickettsia ||Late spring through early fall ||Wild mammals, such as squirrels, opossums, rabbits, dogs, and mice ||Ticks: Dermacentor andersoni, in western US; Dermacentor variabilis in the eastern US; Rhipicephalus sanguineus in Arizona and Mexico ||Southeastern US |
|Ehrlichiosis/Anaplasmosis ||E. chaffeensis; E. ewingii; Anaplasma phagocytophila ||Late spring through early fall ||Deer ||Ticks: Ixodes scapularis and Amblyomma americanum ||Eastern seaboard, South Central, Midwest and Northern California |
|Tularemia ||Francisella tularensis ||Late spring through early fall ||Rabbits, hares and small rodents ||Direct exposure or Ticks ||Central US |
|Rat-bite Fever ||Streptobacillus moniliformis in the US |
|None ||Rats, mice, squirrels ||Direct exposure/bite || |
|Cat-scratch disease ||Bartonella henselae || ||Cats ||Direct exposure || |
Incidence is highest (19 to 77 cases/1 million people in 2008) in Southeastern (Virginia, Carolinas) and Central (Tennessee, Missouri, Arkansas and Oklahoma) US (Figure 188-2).1
Approximately 2,000 cases are reported annually in the US.
1/3 of all cases are in the pediatric age group.2,3
Incidence is highest (14 to 33 cases/1 million people in 2008) in Central States (Missouri, Arkansas and Oklahoma) with moderate incidence (1.7 to 14 cases/1 million people in 2008) in Upper Midwest and Southeastern states (Figure 188-3).1
Approximately 2500 cases were reported in 2010.
Number of reported cases as well as size of endemic regions appears to be growing with spread of tick vectors.