From the Guidelines
Rocky Mountain spotted fever (RMSF) is the most deadly tick-borne disease, with a case-fatality rate of approximately 5%–10% overall, and up to 40%–50% if treatment is delayed until days 8 or 9 of illness. This bacterial infection is caused by Rickettsia rickettsii and is primarily transmitted through the bite of infected ticks [ 1 ]. The disease can rapidly progress to cause serious damage to blood vessels throughout the body, leading to organ failure, neurological damage, and death. Key factors associated with increased risk for death include delayed diagnosis and treatment, age ≥40 years, age <10 years, and alcohol abuse [ 1 ]. Some of the key symptoms of RMSF include:
- Fever
- Headache
- Muscle aches
- A characteristic rash that typically appears 2-5 days after fever onset Prompt treatment with doxycycline is essential to prevent progression of the disease [ 1 ]. The typical adult dosing is 100mg twice daily for at least 7 days or until the patient has been fever-free for 48-72 hours. Children under 45kg typically receive 2.2mg/kg twice daily. Early diagnosis and treatment are critical to reduce the risk of mortality and long-term neurologic sequelae, such as cognitive impairment, hearing loss, and peripheral neuropathy [ 1 ].
From the Research
Tick-Borne Diseases
- Powassan virus (POWV) is considered a deadly tick-borne disease, with a case fatality rate of approximately 10% to 15% 2, 3.
- The virus is transmitted to humans by the bite of infected Ixodes scapularis ticks, primarily in the Northeast and upper Midwest regions of the United States 4, 3.
Symptoms and Diagnosis
- POWV infection can cause severe neurological symptoms, including encephalitis and meningoencephalitis 4, 5.
- Diagnosis is established through a combination of imaging and serologic tests, including enzyme-linked immunosorbent assay and immunofluorescence antibody testing 5.
Epidemiology
- The number of reported POWV cases has increased over the past few decades, with 147 human cases reported in North America as of 2017 6.
- The geographic range of human POWV cases has expanded, and the age distribution of symptomatic cases has shifted, with more individuals over 40 years old being diagnosed 3.