What is Venezuelan Equine Encephalitis and What Causes It?
Venezuelan equine encephalitis is a condition where there is inflammation of the brain and its meninges along with other symptoms. This condition is caused by Venezuelan equine encephalitis virus belonging to Togaviridae family and hence the name of the infection.(1) The Venezuelan equine encephalitis virus belongs to the North American encephalitic arboviruses, which are transmitted to humans via mosquito bites.
What are the Symptoms of Venezuelan Equine Encephalitis (VEE)?
There is an incubation period of 1-5 days after which the infected patients develop flu-like syndrome, along with cervical lymphadenopathy and pharyngitis. Many of the patients completely recover from this infection after a week. About 4% of children affected and around 0.4% adults affected develop encephalitis syndrome consisting of altered mental status, tremors, paralysis or convulsions.
The symptoms of Venezuelan equine encephalitis consist of inflammation of the brain and the meninges of the brain leading to CNS symptoms in the small percentage of patients that develop encephalitis. Venezuelan equine encephalitis can be described as acute, debilitating and of short duration.
The patient suffering from Venezuelan equine encephalitis feels abruptly sick with symptoms that develop to include generalized malaise, rigors, spiking fevers, photophobia, intense headache and myalgia.(1, 2) After this, the patient experiences nausea, cough, vomiting, sore throat, and diarrhea. Patient can achieve complete recovery in about 1 to 2 weeks.
What is the Mode of Transmission of Venezuelan Equine Encephalitis?
As mentioned before the Venezuelan equine encephalitis (VEE) is a mosquito-borne illness caused by an alphavirus from the Togaviridae family (2). The mode of transmission of this disease is through the bite of an infected mosquito.(2)
Incubation Period and Risk Factor of Venezuelan Equine Encephalitis
Everyone is at an equal risk for developing this condition; however, children and older people are most affected by this infection. The Incubation Period of Venezuelan equine encephalitis (VEE) ranges from 1 to 5 days.
Can Venezuelan Equine Encephalitis Be Transmitted From One Human to Another?
The Venezuelan equine encephalitis is extremely infectious when aerosolized.(3) Up till now, there has been no evidence of transmission from human-to-human even though the VEE virus can be found in throat swabs from infected patients. There is no Secondary transmission of Venezuelan equine encephalitis.
How is the Diagnosis of Venezuelan Equine Encephalitis Made?
The diagnosis of Venezuelan equine encephalitis is made through throat swab specimens and the virus can also be isolated from the serum.
Blood tests show an increase in VEE IgG antibody or VEE specific IgM present in a single serum sample indicate recent infection.
Treatment for Venezuelan Equine Encephalitis
Venezuelan equine encephalitis does not have any specific treatment.(3) Patients suffering from uncomplicated Venezuelan equine encephalitis are treated with painkillers to manage and relieve symptoms, such as headache and myalgia.
Patients suffering from Venezuelan equine encephalitis who go on to develop encephalitis need medicines like anticonvulsants and intensive supportive care to maintain electrolyte and fluid balance, for adequate ventilation, and also to prevent any secondary bacterial infections.
Prophylactic Treatment for Venezuelan equine encephalitis consists of a live, attenuated vaccine emerging as an investigational drug.
A formalin-inactivated, killed vaccine can be given for boosting antibody titers in those patients who have received the live vaccine.
What is the Death Rate and Prognosis of Venezuelan Equine Encephalitis?
The mortality rate for Venezuelan equine encephalitis is less than 1%; however, can be higher in children and older patients.(4)
The fatality rate from is 10% to 25% from encephalitis and can be as high as 35% in children who below 5 years of age. Rarely there are neurologic sequelae and the prognosis among survivors of encephalitis for full recovery is excellent.