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Learning objectives

  • Identify the most common acellular pathogens that can cause infections of the nervous system
  • Compare the major characteristics of specific viral diseases affecting the nervous system

A number of different viruses and subviral particles can cause diseases that affect the nervous system. Viral diseases tend to be more common than bacterial infections of the nervous system today. Fortunately, viral infections are generally milder than their bacterial counterparts and often spontaneously resolve. Some of the more important acellular pathogens of the nervous system are described in this section.

Viral meningitis

Although it is much more common than bacterial meningitis, viral meningitis is typically less severe. Many different viruses can lead to meningitis as a sequela of the primary infection, including those that cause herpes , influenza , measles , and mumps . Most cases of viral meningitis spontaneously resolve, but severe cases do occur.

Arboviral encephalitis

Several types of insect-borne viruses can cause encephalitis. Collectively, these viruses are referred to as arboviruses (because they are ar thropod- bo rne), and the diseases they cause are described as arboviral encephalitis . Most arboviruses are endemic to specific geographical regions. Arborviral encephalitis diseases found in the United States include eastern equine encephalitis (EEE), western equine encephalitis (WEE), St. Louis encephalitis, and West Nile encephalitis (WNE). Expansion of arboviruses beyond their endemic regions sometimes occurs, generally as a result of environmental changes that are favorable to the virus or its vector. Increased travel of infected humans, animals, or vectors has also allowed arboviruses to spread into new regions.

In most cases, arboviral infections are asymptomatic or lead to a mild disease. However, when symptoms do occur, they include high fever, chills, headaches, vomiting, diarrhea, and restlessness. In elderly patients, severe arboviral encephalitis can rapidly lead to convulsions, coma, and death.

Mosquitoes are the most common biological vectors for arboviruses, which tend to be enveloped ssRNA viruses. Thus, prevention of arboviral infections is best achieved by avoiding mosquitoes—using insect repellent, wearing long pants and sleeves, sleeping in well-screened rooms, using bed nets, etc.

Diagnosis of arboviral encephalitis is based on clinical symptoms and serologic testing of serum or CSF. There are no antiviral drugs to treat any of these arboviral diseases, so treatment consists of supportive care and management of symptoms.

Eastern equine encephalitis (EEE) is caused by eastern equine encephalitis virus (EEEV), which can cause severe disease in horses and humans. Birds are reservoirs for EEEV with accidental transmission to horses and humans by Aedes , Coquillettidia , and Culex species of mosquitoes. Neither horses nor humans serve as reservoirs. EEE is most common in US Gulf Coast and Atlantic states. EEE is one of the more severe mosquito-transmitted diseases in the United States, but fortunately, it is a very rare disease in the United States ( [link] ). US Centers for Disease Control and Prevention, “Eastern Equine Encephalitis Virus Disease Cases and Deaths Reported to CDC by Year and Clinical Presentation, 2004–2013,” 2014. http://www.cdc.gov/EasternEquineEncephalitis/resources/EEEV-Cases-by-Year_2004-2013.pdf. US Centers for Disease Control and Prevention, “Eastern Equine Encephalitis, Symptoms&Treatment, 2016,” Accessed June 29, 2016. https://www.cdc.gov/easternequineencephalitis/tech/symptoms.html.

Questions & Answers

what is cell
Avi Reply
is unit of life
who is an industrial microbiologist
Cynthia Reply
I want to know the biochemical composition of bacteria
Josh Reply
It contains peptidoglcon, DNA nd RNA
bacteriophage disadvantage
Momina Reply
disease due to __________ abnormalities are termed primary immunodeficiencies
Tayee Reply
Some primary immunodeficiencies are due to a defect of a single cellular or humoral component of the immune system.
Examples of primary immunodeficiencies include: chronic granulomatous disease, X-linked agammaglobulinemia, selective IgA deficiency etc
thank you
explain microbial mutation
what is mutation
Cynthia Reply
alteration in genetic makeup
Hi, I'm new here. I'm Bello Abdul Hakeem from Nigeria.
welcome on board
Thanks brother I'm an undergraduate. I hope to study for MBBS.
pls guys help me out
what is limitation of plate
limitation of plate load test . there are some that should be considered while performing load test which are given below, this test is usually performed on relatively similar plate ,usually 1 or 2 square foot area the reason is that the plate of greater are the economically not feasible
iam new here my name shafiu umar from Nigeria
thanks shafiu
how to differentiate Gram positive from Gram negative bacteria?
by the cell membrane
with gram staining which has 4 steps
Mechanism of bacterial pathogenicity
rashida Reply
write a short note on Algea
najaatu Reply
green minutes plants organisms that are produced in turf.
Algae is a kind of a photosynthetic organism, which is usually grown in the moist areas. These are usually the simple plants that grow near to the water bodies. It contains a kind of chlorophyll pigments that act as a primary coloring agent.
they are eukaryotic and most lived in fresh water. they are photosynthetic that's, they contain chlorophyll and store starch in discrete chloroplast.
are bacteria important to man
just Reply
yes, depending on the type of bacteria .eg the normal florals, the latic acid batteries etc are important to man
I mean latic acid bacterial
I don't understand this topic
Jane Reply
what topic is that
sahi kon hai bhosri ke
saurabh Reply
define metabolism of carbohydrates with example
Thavasi Reply
what is sterilization a
the process of keep equipment free from bacteria
is it only bacteria?
no undesirable fungi and contamination also.
what is streak plate method
what is the biofilm
metabolism is the sum of all the biochemical reaction required for energy generation and use of that energy to synthesize cell materials from small molecules in environment.
what are granulocytes
Shawnitta Reply
granulocytes are type of WBCs which contains granules in the cytoplasm
what is mutation
it is the interchange of genes from their normal sequence
is an heritable change of the base-pair sequence of genetic material
suitable example for prokaryotes
Suvetha Reply
one of the possible early sources of energy was
uv radiation and lighting
e coli is the example of prokaryotes
archaea too

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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