Arbovirus encephalitis is a general term that refers to an inflammation of the brain due to an infection with viral pathogens transmitted by arthropods.
Pathogens are inoculated peripherally, replicate and disseminate through the bloodstream. In immunocompetent patients, this process is generally associated with seroconversion and results in virus clearance. Thus, most patients who contract an arbovirus infection remain asymptomatic or merely develop flu-like symptoms. Neuroinvasion and AE are more likely in those individuals suffering from an immune system disorder, receiving immunosuppressive medication, and the elderly, and occurs in less than 1% of cases .
After an incubation period of a few days, AE patients start to suffer from flu-like symptoms such as fever, headaches, and myalgia. A short period of apparent resolution may pass until additional symptoms manifest, namely nausea, vomiting and meningism with neck stiffness . The onset of neurological symptoms clearly indicates central nervous system involvement, and patients may present with an altered mental status, tremor, myoclonic jerks, seizures, limb weakness, paralysis, and photophobia. Reduced consciousness ranging from somnolence to coma may be observed.
AE-associated symptoms generally persist for few weeks, but may occasionally last several months.
Symptoms presented in the case of AE are unspecific. The consideration of anamnestic data is of utmost importance at the time of establishing a list of differential diagnoses. Patients should be queried about recent journeys and stays in endemic areas as described above.
The following diagnostic measures may be undertaken to confirm a tentative diagnosis of AE:
- Proof of seroconversion.
- An analysis of cerebrospinal fluid regarding the presence of immunoglobulin-M (IgM) antibodies against either of the pathogens described above, is considered the gold standard for the detection of neuroinvasive arboviruses and AE .
- Determination of cerebrospinal fluid/serum antibody ratios, with high ratios indicating central nervous system disease.
- Detection of antigens or nucleic acid by means of molecular biological assays such as polymerase chain reaction, using serum or cerebrospinal fluid samples, (preferred in immunocompromised patients)  .
- Isolation and culture of arboviruses (although difficult and not routinely performed).
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What is the treatment for arbovirus encephalitis? There is no specific treatment for encephalitis and treatment is generally supportive with maintenance of respiratory and circulatory support while the infection runs its course. [laketahoesurgerycenter.com]
Treatment Treatment is mostly supportive, meaning it is directed at improving the symptoms, but does not shorten the course of the illness. [medical-dictionary.thefreedictionary.com]
The role of viral antibody in the development of encephalitis and the use of cortisone in treatment is discussed. [pmj.bmj.com]
Prognosis Prognosis depends on the particular type of arbovirus causing disease, and on the age and prior health status of the patient. [medical-dictionary.thefreedictionary.com]
PROGNOSIS : Secondary bacterial infections of the respiratory and urinary tracts are major complications of acute encephalitis. [atsu.edu]
The presence of arbovirus antibodies may indicate an infection but cannot be used to predict the severity of an individual's symptoms or the person's prognosis. [labtestsonline.org]
It is unclear why patients with viral encephalitis who develop seizures have a worse prognosis. [doi.org]
Pathogens pertaining to distinct families of viruses may trigger the following diseases:
- Bunyaviridae: California encephalitis and sandfly fever
- Flaviviridae: Japanese encephalitis, Murray Valley encephalitis, Powassan encephalitis, St. Louis encephalitis, tick-borne encephalitis, and West Nile Encephalitis
- Togaviridae: Eastern equine encephalitis, Western equine encephalitis, Venezuelan equine encephalitis
Other arboviruses are primarily known to cause systemic febrile disease or hemorrhagic fever, but affected individuals may occasionally develop AE. For instance, this applies to the causative agents of Colorado tick fever, Kyasanur forest disease, and Rift Valley fever .
While arboviruses are distributed throughout the world, specific viruses may only be encountered in determined geographic areas. For instance, the distribution of vectors, as well as wild animals that constitute the natural reservoir of these pathogens, may demarcate affected geographic regions. The latter, in turn, are strongly influenced by climatic conditions, and the climate change may entail the expansion of arboviruses . To date, distribution patterns of AE are as follows :
- California encephalitis: North America
- Sandfly fever: Europe, northern Africa, Middle East and South Asia
- Japanese encephalitis: Asia, Pacific islands , northern Australia
- Murray Valley encephalitis: Australia
- Powassan encephalitis: North America, Russia
- St. Louis encephalitis: Americas, Europe, and Asia; highest incidence rates reported in the United States
- Tick-borne encephalitis: Europe and Asia
- West Nile fever: worldwide; highest incidence rates reported in northern Africa and the Middle East
- Eastern equine encephalitis: America
- Western equine encephalitis: America
- Venezuelan equine encephalitis: America
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test California (LaCrosse) Virus: California (LaCrosse) virus is a member of the Bunyaviridae family and is one of the arthropod-borne [mayomedicallaboratories.com]
The authors demonstrate that ZIKV infects human cortical neural progenitors in vitro, offering pathophysiologic support to the causal link between ZIKV congenital infection and microcephaly. CrossRef PubMed Google Scholar 83. [link.springer.com]
High incidence of seizures in HSV encephalitis is thought to be mainly due to the involvement of the highly epileptogenic mesial temporal lobes, but it may also reflect other pathophysiological processes, such as haemorrhage, necrosis, and neuroimmunological [doi.org]
How can tickborne encephalitis be prevented? Although vaccines are available in Europe, current data does not support travelers receiving the vaccine. [laketahoesurgerycenter.com]
Prevention Prevention involves avoiding contact with arthropods which carry these viruses. This means wearing appropriate insect repellents, and dressing properly in areas known to be infested. [medical-dictionary.thefreedictionary.com]
For secondary prevention, we aim to review whether the use of antiepileptic drugs after a seizure in patients with proven or suspected viral encephalitis is effective in preventing further seizures, improving outcome and reducing the risk of subsequent [doi.org]
Viral encephalitis is a type of encephalitis caused by a virus.It is unclear if anticonvulsants used in people with viral encephalitis would prevent any seizures. [en.wikipedia.org]
Arbovirus is a non-taxonomic term coined to refer to viral pathogens transmitted by arthropods. In detail, humans may contract an infection with an arthropod-borne virus after getting bitten by mosquitoes, flies or ticks. Furthermore, infected organ transplants and blood products constitute possible sources of infection  . Patients suffering from an arbovirus infection may present with systemic febrile illness, hemorrhagic fever or encephalitis. Pathogens that may provoke arbovirus encephalitis (AE) and corresponding entities are detailed below.
- Dana A, Antony A, Patel MJ. Vector-borne infections in solid organ transplant recipients. Int J Dermatol. 2012; 51(1):1-11.
- Macedo de Oliveira A, Beecham BD, Montgomery SP, et al. West Nile virus blood transfusion-related infection despite nucleic acid testing. Transfusion. 2004; 44(12):1695-1699.
- Salimi H, Cain MD, Klein RS. Encephalitic Arboviruses: Emergence, Clinical Presentation, and Neuropathogenesis. Neurotherapeutics. 2016; 13(3):514-534.
- Weaver SC, Reisen WK. Present and future arboviral threats. Antiviral Res. 2010; 85(2):328-345.
- Gubler DJ. The global emergence/resurgence of arboviral diseases as public health problems. Arch Med Res. 2002; 33(4):330-342.
- Guillaumot L. Arboviruses and their vectors in the Pacific--status report. Pac Health Dialog. 2005; 12(2):45-52.
- Davis LE, Beckham JD, Tyler KL. North American encephalitic arboviruses. Neurol Clin. 2008; 26(3):727-757, ix.
- Petersen LR, Marfin AA. West Nile virus: a primer for the clinician. Ann Intern Med. 2002; 137(3):173-179.
- Debiasi RL, Tyler KL. Molecular methods for diagnosis of viral encephalitis. Clin Microbiol Rev. 2004; 17(4):903-925, table of contents.
- Penn RG, Guarner J, Sejvar JJ, et al. Persistent neuroinvasive West Nile virus infection in an immunocompromised patient. Clin Infect Dis. 2006; 42(5):680-683.