Approach Considerations
Like all disease caused by alphaviruses, eastern equine encephalitis (EEE) has no specific treatment. [14] Focus management primarily on supportive and preventive measures. Pharmacologic therapy primarily consists of antipyretics, analgesics, and anticonvulsants. If the syndrome of inappropriate antidiuretic hormone secretion (SIADH) is present, treat accordingly.
Carefully stabilize the patient before any other activity. Once the patient is comatose, undertake obvious measures (eg, respiratory maintenance with ventilator support in a critical care unit [CCU]). Additionally, as with all critically ill patients, carefully provide adequate nutritional support. No special dietary restrictions exist. Transfer an infected patient to the intensive care unit (ICU) when appropriate.
Assess the many issues secondary to the high mortality of the disease. Ensure that a social worker and appropriate hospital services staff are available to the patient’s family.
No direct surgical treatments for this disease are available, except for the appropriate neurologic measures necessary to deal with significant central nervous system (CNS) bleeding or the consequences of markedly elevated CNS pressure.
See the following for more information:
Consultations
Consultations are obtained primarily for supportive measures. The following consultations may be helpful:
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Infectious disease specialist - Particularly relevant when the etiology of the encephalitis or meningoencephalitis is difficult to determine (his or her most important contribution will likely be the ability to rapidly determine a potentially reversible cause of the patient’s symptoms)
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Neurologist - May provide early insightful information and aid with the diagnosis (via EEG) and treatment of complications
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Critical care specialist - Valuable for coordinating ICU care if a general practitioner is treating the patient
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Neurosurgeon - Needed only for treatment of neurologic complications or performance of brain biopsy
Long-Term Monitoring
Patients who survive infection usually need extensive rehabilitation. On the basis of the duration of symptoms and the extent of neurospasticity, schedule the patient for physical therapy upon recovery. In addition, depending on the specific defect, a patient may need consultations with speech and auditory therapists.
Because of the potential for high neurologic morbidity, arrange coordinated care and quality follow-up care. Patients often require close neurodiagnostic follow-up care. The primary care physician must also be aware of subtle changes in behavior, intelligence, and motor skills.
Pharmacologic Therapy
There is no specific pharmacologic therapy for EEE. Drugs currently used are those capable of ameliorating neurologic complications (eg, anticonvulsants). No current studies provide convincing evidence for or against prophylactic use. Medications that may be given include phenytoin, phenobarbital, and a benzodiazepine drip.
Use antipyretics as needed. Additionally, appropriate analgesics and amnestics may be used once the patient is intubated. Antibiotics are not of value in these situations and may predispose patients to superinfections. After determining that the patient does not have a bacterial infection, discontinue antibiotics.
Empiric drug therapy
Because EEE can mimic other encephalitides, meningitis, or meningoencephalitis, empiric drug therapy for these conditions should be implemented promptly. Antibiotic therapy for generalized coverage of bacterial meningitis (as appropriate for age and antibiotic resistance patterns) and acyclovir to treat herpes simplex virus (HSV) infection should be started until these diseases are ruled out.
Although ribavirin has in vitro activity against this virus, the benefit of administering it in the early viremic stage has not been established.
Experimental therapies
Although no current medical therapies exist for EEE, recent research reveals some possibilities. An antibody with appropriate specificity attenuates the intracellular processes necessary for viral replication in animal models. The antibody binds to cell-specific markers of infected cells and initiates an intracellular cascade, which interferes with viral reproduction. Cytotoxic T cells also play an important part in the recovery from CNS lesions in mice.
Early studies attempted to use pyrimidine derivatives and isoprinosine, a derivative of inosine, for treatment, but in vivo results were poor. [15] Nucleoside analogs (eg, ribavirin) also have in vitro activity, but no clinical application is apparent.
A novel quinazolinone known as BDGR-49 has shown efficacy in animal trials of stopping viral replication directly within brain tissue with good specificity and efficacy. The drug is still in the pre-clinical stage and under investigation for broader application. [16]
Whether or not these therapies can be productive in humans remains questionable.
Prevention
Environmental animal control
Monitoring the sources of infection may be possible by assessing the serology of anti-EEE antibodies in certain wild birds or in caged flocks of sentinel birds (eg, chickens). The virus also may be recovered from adult mosquitoes and may provide an opportunity for screening in possible vector habitats. Officials should control the vector mosquito population in areas where the virus has been isolated or where the risk for infection is high.
Global measures
Global factors also play a role in future prevention and spread. If global temperatures continue to rise and sea levels rise, the swampy breeding habitat of the C melanura mosquito and other bridge vectors may expand.
Public information
Warn individuals who live in or travel to high-risk areas to take the necessary precautions. [17] This includes wearing appropriate clothing (eg, long pants, long-sleeved shirts), wearing mosquito repellent, avoiding areas with high mosquito activity, and avoiding outside activity during times of day when mosquitos are active. Mosquito netting at nighttime can be used if appropriate.
Permethrin 5% cream on exposed skin areas can prevent arthropod bites for up to a week. The drug does not repel arthropods effectively, but it deters biting and causes the insects to die after contact with the treated skin. [18] Permethrin rinse in clothing has been shown to be partially effective in preventing arthropod bites.
Vaccination
Currently, a vaccine is available for the North American subtype of EEE; however, it is not in widespread use and may not be effective against certain antigenic variants that are found primarily in other countries. At present, its use is limited to environmental workers at high risk for exposure. Studies of advances in experimental vaccination have yielded equivocal results. The current vaccine has a weak antigen and requires multiple immunizations to achieve protection.
Surveillance
EEE is reportable under the National Notifiable Diseases Surveillance System. Additionally, electronic surveillance is conducted through ArboNet, a Centers for Disease Control and prevention (CDC) site used to assist states in tracking mosquito-borne viruses.
Screening
To enable appropriate precautions, states with known mosquito-borne illnesses now are also screening vectors to determine if certain counties contain an increased number of carriers.
