5-66
Malaria - rule out with serial blood smears.
Measles (rubeola) - coryza, respiratory symptoms, Koplik spots, discrete rash from face to trunk
Rubella - postauricular lymph nodes in children
Meningococcal fever - painful, palpable purpura and shock
Rickettsial or other bacterial fevers - vesicular or petechial rashes including the palms and soles.
Other viral hemorrhagic fevers - see ID: Yellow Fever and CBR: Viral Hemorrhagic Fever
Plan:
Treatment
There is no specific treatment. Treat symptoms including pain (e.g., Codeine, see Procedure: Pain
Assessment and Control).
Patient Education
General: Use body fluid precautions with patient. Prevent mosquito access to patient.
Activity: Bed rest
Diet: Regular, maintain fluids
Prevention and Hygiene: Use personal protection against insect bites. Avoid exposure to mosquitoes at
dusk, remove breeding sites (see Preventive Medicine chapter)
No Improvements/Deterioration: Consider hemorrhagic fevers including DHF or yellow fever.
Follow-up Actions
Evacuation/Consultation Criteria: Evacuate all DHF cases early and urgently, as well as all dengue patients
who cannot complete the mission. Consult infectious disease experts for all DHF patients.
ID: Arboviral Encephalitis
LTC Niranjan Kanesa-thasan, MC, USAIntroduction: Arthropod-borne viruses (arboviruses), including Japanese encephalitis (JE), West Nile (WN),
tick-borne encephalitis (TBE), St. Louis encephalitis (SLE), Kunjin, and Murray Valley encephalitis (MVE)
flaviviruses have been associated with sporadic fatal meningoencephalitis in humans. Typically, many
hundreds of asymptomatic infections occur for each clinical case of encephalitis. Less common causes
of arboviral encephalitis include the alphaviruses: Western equine encephalitis (WEE), Eastern equine
encephalitis (EEE), Venezuelan equine encephalitis (VEE); and the California group (CG) of bunyaviruses
such as La Crosse virus (LAC). Japanese encephalitis is the most common and one of the most dangerous
arboviral encephalitides (inflammation of the brain tissue), with over 50,000 cases reported annually. 25% of
individuals with JE die from the disease and 50% are left with permanent neurologic or psychiatric sequelae.
There are few clinical features to distinguish the types of encephalitis, so half the cases do not have a specific
pathogen isolated. Birds (JE, WN, SLE), horses (WEE, EEE, VEE), and other animals play prominent roles
as natural reservoirs for these pathogens, and humans are an accidental host. The alphaviruses and some
flaviviruses (JE, SLE, MVE) are associated with epidemic disease in susceptible human populations. Case
fatality rates from arboviral encephalitis range from <10% (WN, WEE, SLE, TBE) to 60% (EEE). Geographic
Association: WN virus is widely dispersed through Asia, Africa, the Middle East, and recently the U.S. JE
virus is distributed throughout Asia, including India and China. TBE is found in forested areas throughout
Europe and Central Asia. SLE is widely distributed in the Americas. Kunjin and MVE are restricted to
Australia and New Guinea. The alphaviruses and most CG viruses are principally found in the Americas.
In highly endemic areas, adults are usually immune to these arboviruses through previous asymptomatic
infection. Seasonal Variation: These diseases are associated with periods of vector (usually mosquito)
abundance, typically warm and wet times of the year in the tropics. In the U.S., cases of encephalitis usually
peak in the late summer/early fall. Risk Factors: Exposure to infectious viruses in vectors or animal hosts
commonly occurs in rural or suburban areas (JE, SLE, CG, WEE, EEE), but SLE and WN viruses in particular
may occur in urban outbreaks. Children especially those < 1year of age are at risk for severe disease with
death or neurologic sequelae with WEE, EEE, JE, and LAC, while older adults > 55 years of age are at
greater risk with SLE, WN, and VEE viruses.