HWN Suggests

St. Louis Encephalitis: Real or Myth?

St. Louis Encephalitis sounds like something made up by a local, doesn’t it? Actually, St. Louis Encephalitis (SLE) is a real thing, which might have you wondering “I live in St. Louis, how have I never heard of it?” We will get to that, but let’s start with what it is...

The common symptoms are fever, headache, nausea, dizziness and they only last a few days before the infected person fully recovers. However, for a few, (mostly elderly) the symptoms can affect the central nervous system...

It is true that SLE was named after St. Louis. That’s because the first known outbreak in the U.S. was here in 1933. It was an outbreak of epidemic proportion with over 1,000 reported…

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Articles of Interest

Epidemiologic and environmental characterization of the Re-emergence of St. Louis Encephalitis Virus in California, 2015–2020

St. Louis encephalitis virus is a mosquito-borne virus that can cause human disease and is found in California, where it was detected every year from 1938 to 2003. However, after West Nile virus arrived in 2003, St. Louis encephalitis virus was not detected again until 2015, when it re-emerged in Riverside County.

StatPearls

Saint Louis encephalitis virus is transmitted to humans from the bite of an infected Culex species mosquito. It is a flavivirus, a single-stranded RNA virus, which is closely related to the Japanese encephalitis, Powassan and West Nile virus. Most cases occur in the eastern and central United States during the summer and early fall.

What is St. Louis Encephalitis and How Does it Spread?

St. Louis encephalitis virus (SLEV) belongs to the virus family Flaviviridae and is related to Japanese encephalitis virus. The virus was first recognized in 1933 when an epidemic in St. Louis, Missouri resulted in over 1,000 cases of encephalitis. Several epidemics have occurred sporadically throughout the U.S. since then, with the majority of cases occurring in eastern and central states.

Resources

CDC

Some people may develop neuroinvasive disease, such as encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes that surround the brain and spinal cord).

Radiopaedia

Before the establishment of West Nile virus, SLEV was the leading cause of Flavivirus encephalitis in North America 1. The incidence of SLE has since decreased significantly. Symptomatic infection occurs in <1% of exposed adults. An acute-onset, nonspecific febrile illness - malaise, myalgia, headache, nausea, cough and dizziness - precedes the development of neuroinvasive disease 3,4. Meningitis and encephalitis occur in 40% and 50% of patients under 20 years old, respectively. More than 90% of those over 60 years old develop encephalitis 4. Features of encephalitis most commonly include seizures, coma and reduced consciousness; tremors, myoclonic jerks, opsoclonus, nystagmus and ataxia have also been reported