Venezuelan Equine Encephalitis (VEE) is a dangerous illness that poses a serious threat to both human and animal populations. This virus, which has its origins in the heart of South America, has spread internationally. In this article, we set out to explore the complexities of Venezuelan Equine Encephalitis, exploring the complex network of symptoms and therapeutic approaches.
Introduction
The virus that causes Venezuelan Equine Encephalitis, or VEE for short, is mostly spread by the biting of infected mosquitoes, especially those of the genus Culex and Aedes. The Venezuelan Equine Encephalitis Virus (VEEV) is a member of the Togaviridae family's Alphavirus genus. After being discovered in horses in Venezuela in the 1930s, VEEV has spread across South and Central America, occasionally causing epidemics that have serious consequences for public health.1
The transmission cycle of VEEV is complicated and involves both vertebrate and invertebrate hosts. Horses are the virus's amplifying hosts, helping it to replicate and spread, but humans and other animals can also get infected. In North America, there are only 5 to 6 documented instances of VEEV infection in humans annually on average.
Due to spillover from avian–mosquito swamp cycles, more cases affect equines and other domesticated animals. In both situations, the case fatality rate exceeds 50%.2
The virus can produce mild flu-like symptoms to more severe symptoms such as encephalitis, hence its name.
Understanding venezuelan equine encephalitis
The disease’s name comes from its first discovery in horses in Venezuela in the 1930s. Since then, the virus has expanded throughout Central and South America, causing epidemics in these areas. In the past, VEE has also spread to other regions of North America, especially Texas and the southern United States of America, where it has sometimes caused outbreaks and new cases.
Numerous factors, such as temperature, mosquito numbers, and animal movement patterns affect the regional distribution of the disease. The virus still poses a concern in areas where it is prevalent, despite attempts to prevent and control epidemics.3
The primary method of VEE transmission is via mosquito bites: Infected mosquitoes act as the primary vectors of the virus and especially Aedes and Culex mosquito species are linked to the spread of VEE. Horses, humans, and other animals are among the vulnerable hosts that mosquitoes may infect and spread the virus to.
Since horses may experience high levels of viremia, which is the presence of the virus in blood and aids in the virus's reproduction and spread to other mosquitoes, horses are regarded as amplifying hosts for VEE. Mosquito bites may infect humans and other mammals as well, but these hosts are usually dead-ends with little chance of spreading the infection further.1
Symptoms of venezuelan equine encephalitis
After exposure to the virus, early signs of Venezuelan Equine Encephalitis (VEE) usually appear a few days to a week later. Early diagnosis can be difficult since these early symptoms might be non-specific and similar to those of common viral illnesses. On the other hand, early detection of these symptoms is essential for timely medical assessment and treatment.
The main early signs of VEE are:
Fever
Fever is frequently one of the initial symptoms to manifest after a VEEV infection. Other flu-like symptoms are typically present along with the fever, which can range in intensity from mild to severe. Timely management of fever includes monitoring body temperature and seeking medical assistance if fever worsens or continues.4
Malaise
In the early phases of the illness, people with VEE frequently describe feeling generally uneasy or uncomfortable. This general feeling of being unwell may come on before other symptoms appear.5
Headache
During the early stages of the illness, people with VEE frequently complain about headaches. The strength of the headache might fluctuate and can be accompanied by other symptoms like phonophobia (sensitivity to sound) or photophobia (sensitivity to light). Pain can be reduced by controlling headache symptoms with rest, water, and over-the-counter painkillers.5
Myalgia
Muscle pain is another typical early sign of VEE. People who are affected may feel localised pain in particular muscle groups or widespread soreness in their muscles. This symptom may make it more difficult to go about daily tasks and increase feelings of weariness and pain.5
People may develop a variety of neurological symptoms when VEE worsens, which can have a serious negative influence on their health and general well-being. These symptoms usually appear after an initial period of flu-like symptoms and may be a sign of serious VEE consequences. It is essential to identify these neurological symptoms to receive timely medical attention and treatment.
The following neurological symptoms were seen in VEE.
Severe headache
As the illness worsens, people may get more intense headaches that are frequently incapacitating. These headaches might not be the same as the first headache felt in the early stages of VEE and they might be accompanied by other neurological symptoms such as light or sound sensitivity, or photophobia and phonophobia.5
Confusion and disorientation
Cognitive impairment, such as confusion, disorientation, and changed mental status, can result from the progression of VEE. Those who are affected could find it difficult to focus, digest information, or comprehend their environment. This bewilderment and disorientation might show up as forgetfulness, trouble following directions, or trouble making decisions.1
Seizures and coma
People with severe VEE may either go into a coma or have seizures.1 Seizures may cause abrupt, uncontrollable movements or convulsions, and they may even cause unconsciousness.6 Coma, which is defined as a profoundly unconscious condition, can happen when the infection causes significant brain damage.7
Diagnosis of venezuelan equine encephalitis
The diagnosis of Venezuelan Equine Encephalitis (VEE) requires a multistep approach that includes imaging techniques, laboratory testing, and clinical examination to determine the degree of neurological impairment and establish the presence of the virus. Usually, the diagnostic procedure entails:1,8
Clinical examination
It takes a comprehensive clinical evaluation, including a neurological assessment, to find symptoms and indicators that point to VEE. Assessing the patient's mental state, reflexes, motor abilities, and sensory perception may be part of this. A thorough medical history that includes recent travel to areas where the virus is endemic, mosquito contact, and any previous symptoms like fever, headaches, or muscular soreness might give important information about the possibility of a VEE infection.
Laboratory tests
The patient's blood serum or cerebrospinal fluid (CSF) will be tested serologically to look for antibodies specific to the Venezuelan Equine Encephalitis Virus (VEEV). The plaque reduction neutralization test (PRNT) and the enzyme-linked immunosorbent assay (ELISA) are two frequently used procedures to discover VEEV antibodies. Pleocytosis (increased white blood cell count) and increased protein levels may be found by CSF examination.
Additionally, viral isolation will be carried out, which entails trying to cultivate the VEE virus from human tissue, cerebrospinal fluid, or blood samples. Although this approach takes time and needs specialized lab equipment, it can offer conclusive proof of VEEV infection. Viral RNA may also be found in clinical samples using polymerase chain reaction (PCR) tests, which enables quick confirmation of VEEV infection.
Treatment options for venezuelan equine encephalitis
The main form of treatment for Venezuelan Equine Encephalitis (VEE) is supportive and palliative care, which aims to reduce symptoms, avoid complications, and boost the body's immune system against the infection. Although there aren't many particular antiviral treatments for VEE, supportive care is still essential for treating the condition. Options for supportive therapy include:9
Nutrition and hydration
For people with VEE, staying hydrated is extremely important, especially if patients are suffering from fever, vomiting, or diarrhoea, as these symptoms can cause dehydration. It may be necessary to give IV fluids to maintain electrolyte balance and hydration. Sufficient food intake boosts the immune system and keeps the body functioning when one is sick. Consuming well-balanced meals and nutritional supplements if needed will help promote healing and strengthen the body's defenses against viral encephalitis.
Pain management
Pain management techniques, including taking acetaminophen or nonsteroidal anti-inflammatory medicines (NSAIDs), may be recommended and are useful to treat VEE symptoms like headaches, pains in the muscles, and joint discomfort. These steroids will also help in relieving intercranial tension.
Other experimental research revealed the potential of a live-attenuated vaccine of a strain of the VEE virus, called TC-83. This vaccine has shown immunity to around 80% of people who have been vaccinated with it but it has been noted that milder symptoms of the VEE virus have been experienced by the vaccine.10
Summary
Venezuelan Equine Encephalitis (VEE) is a serious threat to the public because of its ability to create outbreaks in certain areas and serious neurological consequences. Raising awareness about VEE among individuals and medical professionals is essential in the battle against this illness. Through comprehension of the dangers, identification of the symptoms, and more research towards cures for it, we can mitigate the impact of VEE.
We will need to keep researching and working together to improve our understanding of VEE and create better preventative, diagnostic, and therapeutic approaches.
References
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- Carrera JP, Forrester N, Wang E, Vittor AY, Haddow AD, López-Vergès S, et al. Eastern Equine Encephalitis in Latin America. The New England Journal of Medicine [Internet]. 2013 Aug 22 [cited 2024 Feb 12];369(8):732–44. Available from: https://www.nejm.org/doi/full/10.1056/NEJMoa1212628
- Smith DR, A. Paige Adams, Kenney JL, Wang E, Weaver SC. Venezuelan equine encephalitis virus in the mosquito vector Aedes taeniorhynchus: Infection initiated by a small number of susceptible epithelial cells and a population bottleneck. Virology [Internet]. 2008 Mar 1 [cited 2024 Feb 13];372(1):176–86. Available from: https://www.sciencedirect.com/science/article/pii/S0042682207006642?via%3Dihub
- Bernal León, Käsbohrer A, Hutter SE, Baldi M, Firth CL, Juan José Romero-Zúñiga, et al. National Seroprevalence and Risk Factors for Eastern Equine Encephalitis and Venezuelan Equine Encephalitis in Costa Rica. Journal of Equine Veterinary Science [Internet]. 2020 Sep 1 [cited 2024 Feb 21];92:103140–0. Available from: https://www.sciencedirect.com/science/article/pii/S0737080620302318?via%3Dihub#cebib0010
- Camilo Guzmán-Terán, Calderón-Rangel A, Rodriguez-Morales A, Mattar S. Venezuelan equine encephalitis virus: the problem is not over for tropical America. Annals of Clinical Microbiology and Antimicrobials [Internet]. 2020 May 19 [cited 2024 Feb 21];19(1). Available from: https://ann-clinmicrob.biomedcentral.com/articles/10.1186/s12941-020-00360-4
- Huff JS;Murr N. Seizure [Internet]. 2023 [cited 2024 Feb 21]. Available from: https://pubmed.ncbi.nlm.nih.gov/28613516/
- Huff JS;Tadi P. Coma [Internet]. 2023 [cited 2024 Feb 21]. Available from: https://pubmed.ncbi.nlm.nih.gov/28613473/
- Vina-Rodriguez A, Eiden M, Keller M, Hinrichs W, Groschup MH. A Quantitative Real-Time RT-PCR Assay for the Detection of Venezuelan equine encephalitis virus Utilizing a Universal Alphavirus Control RNA. BioMed Research International [Internet]. 2016 Jan 1 [cited 2024 Feb 21];2016:1–7. Available from: https://pubmed.ncbi.nlm.nih.gov/28042576/
- Kumar R. Understanding and managing acute encephalitis. F1000Research [Internet]. 2020 Jan 29 [cited 2024 Feb 21];9:60–0. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6993835/
- Azar SR, Campos RK, Bergren NA, Camargos VN, Rossi SL. Epidemic Alphaviruses: Ecology, Emergence and Outbreaks. Microorganisms [Internet]. 2020 Aug 1 [cited 2024 Feb 21];8(8):1167–7. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7464724/