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Chapter 188: Zoonoses

Lara Danziger-Isakov, MD, MPH; Camille Sabella, MD

Patient Story

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.

FIGURE 188-1

Petechial rash characteristic of late Rocky Mountain Spotted Fever (RMSF). (Used with permission from Johanna Goldfarb, MD.)

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Introduction

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
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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
Spirillum minus		 None Rats, mice, squirrels Direct exposure/bite
Cat-scratch disease Bartonella henselae Cats Direct exposure

Epidemiology

  • RMSF

    • 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

  • Ehrlichiosis

    • 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.

  • Tularemia

    • Rare; only 124 cases were reported in the US in 2010.1

  • Cat-scratch

    • Uncommon, although not routinely reported through National Notifiable Disease Surveillance System (NNDSS) at the Centers of Disease Control and Prevention (CDC).

  • Rat-bite fever.

    • Rare, ...

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