Eastern Equine Encephalitis (EEE) in New Hampshire

Division of Public Health Services

New Hampshire Department of Health and Human Services

Eastern Equine Encephalitis (EEE)

in New Hampshire

Dianne Donovan, BSc

Arboviral Surveillance Coordinator

[email protected]

(603) 271-5927



EEE Transmission Cycle

Mosquito vector

Bird reservoir hosts



EEE History

• 1831 – Horses in MA afflicted with an unknown encephalitis virus

• 1933-1935 – Multiple equine outbreaks along the eastern seaboard

• 1938 – 1st human case in NE reported. MA: 34 human cases, 248 equine

• 1955-1959 – MA reported 16 human cases; NJ reported 33 human cases



EEE Human Cases, MASS, 1974-2006

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# o

f C

ases



EEE



NH Historical Perspective (EEE)• 1973 – 75 equine deaths; 12,000

pheasant deaths

• 1978 – 28 equine deaths

• 1980 – 1 human case reported (not confirmed), 1 equine death

• 1982 – 1 equine death



NH Historical Perspective (EEE)

• 2004: EEE detected in horses, birds, and mosquitoes

• 2005: Human cases

- 7 reported human cases (2 died)

- EEE detected in numerous non-human mammals, birds, and mosquitoes



NH Historical Perspective (EEE)

• 2006: EEE detected in horse, birds, and mosquitoes

• 2007: 3 reported human cases

- EEE detected in mosquitoes, a horse, an alpaca





EEE Symptoms &Clinical Features



EEE - Symptoms• Incubation 4-10 days

• No symptoms in some people infected

• Severe symptoms in others

- short prodrome, ~5 days (fever, headache, abdominal distress)

– Progresses to disorientation, seizures, muscle weakness, paralysis, coma, death



EEE - Clinical Features

• Common: F (83%), HA (75%), N/V (61%)

< 50%: confusion, myalgia, abd pain

< 10%: sore throat, diarrhea, CN palsies

• Imaging (CT, MRI) abnormal in two-thirds of patients

Source: Deresiewicz NEJM 1997



Laboratory Findings(severe neurological disease)

Peripheral Blood

• Normal or elevated total leukocyte count

• Lymphocytopenia

• Anemia

• Hyponatremia



Laboratory Findings(severe neurological disease)

Cerebrospinal Fluid

• Pleocytosis (usually with a predominance of lymphoctyes)

• Elevated protein

• Normal glucose levels



EEE - Diagnosis and Prognosis

• Diagnosis by IgM serum/CSF– Confirmation by PRNT

• Mortality rate 35%

• Neurological sequelae in 30% of survivors

• Lifetime expenses = $3 million/case



EEE Treatment

• There is NO specific treatment.

• Care of patients centers around supportive treatment of symptoms and complications.

• Vaccine – only available for horses.



NH EEE PATIENTS

Demographic & Clinical Characteristics




Age: Mean = 40 years

Range = 4-80 years

Gender: 8 males; 2 females

Onset Date: Earliest = August 3

Latest = October 1




Prodromal Signs & Symptoms:

Fever 9/10

Weakness 9/10

Fatigue 9/10

Headache 8/10

Myalgias 7/10

N/V 7/10




Prodrome Duration (Days):

Mean – 7 days

Range - <1 to ~15 days

SEIZURES: 4/10

COMA: 5/10 DEATHS: 2/10



Suspect Case Reporting



Criteria for Report (a, b, or c)

a. Any patient with viral encephalitis with

- Fever > 100 F

- CNS involvement

- Abnormal CSF profile suggesting a

viral etiology

b. Any patient with presumptive aseptic

meningitis

c. Guillain-Barre syndrome



Criteria for Report

• Severe arboviral disease has occurred in patients of all ages.

• Consider patient travel history in off-season months. Year-round transmission is possible in some areas of the country.





PREVENTION



Personal Protection Works

• Wear long sleeves and pants in light colors to minimize the opportunities for mosquitoes to bite.

• Limit outside activity between evening and dawn when mosquitoes are most likely to bite.

• Consider using an effective insect repellent.





Insect Repellents



Mosquito Repellents: CDC Recommendations

• DEET - Used for >50 years, with millions of

doses applied - Long-term safety established - In children: American Academy of

Pediatrics affirms use of DEET (up to 30%) over 2 months of age



Mosquito Repellents: CDC Recommendations

• Picaridin - Used for years in Australia and Europe - Concentration available in US less - No serious toxicity reported

• Oil of Lemon Eucalyptus - plant derived compound - No serious toxicity reported - Recommended for children >3 years



The Bottom Line

• Repellent adverse reactions, when used appropriately are extremely rare

• EEE (and other mosquito-borne diseases) are definite, recognized threats to human health

- Certain situations (risk factors for severe disease, outbreak situations) increase risk

- Problems following arboviral neuroinvasive disease can be permanent



Repellent Resources

U.S. Environmental Protection Agency

http://www.epa.gov/pesticides/health/mosquitoes/insectrp.

htm

National Pesticide Information Center

http://npic.orst.edu/wnv/



The 2008 Season?



2008 Season?

• Unable to forecast the exact level of risk

• NH communities with prior year’s EEE activity should consider mosquito-borne illness to be a human health risk for 2008





Questions?

Documents

Eastern Equine Encephalitis (EEE) in New Hampshire