An Introduction to the VirusesNon-Living Etiologies

Cytopathic effect (CPE) (or Cytopathogenic effect) refers to degenerative changes in cells, associated with the multiplication

of certain viruses.

Thus identification of a viral infection can be made by examining the characteristic cytopathic effect produced on different cell sheets.

Influenza, commonly referred to as the flu, is an infectious disease caused by RNA virusesof the family Orthomyxoviridae (the influenza viruses), that affects birds and mammals.

The name influenza is Italian and means "influence" (Latin: influentia).

The most common symptoms of the disease are chills, fever, sore throat, muscle pains, severe headache, coughing, weakness and general Discomfort.

The 2009 flu pandemic is a global outbreak of a new strain of influenza A virus subtype H1N1, first identified in April 2009, which is officially termed novel H1N1 and commonly called swine flu.

The virus is a mixing of four known strains of influenza A virus: one endemic in humans, one endemic in birds, and two endemic in pigs (swine).

Transmission of the new strain is typically human-to-human; eatingcooked pork products will not transmit the virus.

The reported mortality rate of highly pathogenic H5N1 avian influenza in a human is high; WHO data indicates that 60% of cases classified as H5N1 resulted in death.

However, there is some evidence that

the actual mortality rate of avian flu could be much lower, as there may be many people with milder symptoms who do not seek treatment and are not counted.

Arbovirus is a shortened name given to

viruses that are transmitted by arthropods,

or arthropod-borne viruses.

Arthropods are able to transmit the virus

upon biting allowing the virus to enter the

bloodstream which can cause viraemia.

The majority of the Arboviruses are RNA

viruses.

Symptoms consist of a mild infection such

as a fever or a rash.

Others however are epidemic and can

cause serious infections such as meningitis

and encephalitis that can be fatal

WEE St. LouisEEE West NileVEE Dengue Fever

Dengue fever is an acute febrile diseases, found in the tropics, and caused by four closely related virus serotypes of the genus Flavivirus, family Flaviviridae.

Herpes simplex is a viral disease

caused by both herpes simplex virus

1 (HSV-1) and herpes simplex virus 2

HSV-2). Herpes viral disease caused by

varicella zoster virus.

Infection with the herpes virus is

categorized into one of several distinct

disorders based on the site of infection.

Oral Herpes, the visible symptoms of

which are colloquially called cold sores,

infects the face and mouth. Oral herpes is

the most common form of infection.

Genital herpes, commonly known simply as

Herpes, is the second most common form

of herpes

Common infection of the skin or mucosa may affect the face and mouth (orofacial herpes), genitalia (genital herpes), or hands (herpes whitlow).

More serious disorders occur when the virus infects and damages the

eye (herpes keratitis), or invades the central nervous system, damaging the brain (herpes encephalitis).

The central nervous system is made

up of the brain and spinal cord. The

brain functions to receive nerve impulses

from the spinal cord and cranial nerves.

The spinal cord contains the nerves that

carry messages between the brain and the

body.

The rabies virus spreads through the

nerves of the brain and spinal cord first

causing flu-like symptoms such as fever

and malaise.

As the disease advances it causes anxiety,

confusion, brain dysfunction, progressing

to hallucinations, delirium, and insomnia.

If left untreated, rabies is nearly always

fatal.

The incubation period for Ebola Hemorrhagic

Fever ranges from 2 to 21 days.

The onset of illness is abrupt and is

characterized by fever, headache, joint and

muscle aches, sore throat, and weakness,

followed by diarrhea, vomiting, and

stomach pain.

A rash, red eyes, hiccups and internal and

external bleeding may be seen in some

patients.

Researchers do not understand why some

people are able to recover from Ebola HF

and others are not.

However, it is known that patients who die

usually have not developed a significant

immune response to the virus at the time of

death.

Smallpox is an infectious diseaseunique to humans, caused by either of two virus variants, Variola major and Variola minor.

Smallpox localizes in small bloodvessels of the skin and in the mouth and throat.

In the skin, this results in a characteristic maculopapular rash, and later, raised fluid-filled blisters. V. major produces a more serious disease and has an overall mortality rate of 30–35%.

Acquired immune deficiency Syndrome (AIDS) is a disease of the human immune system caused by the Human Immunodeficiency Virus (HIV).

HIV causes AIDS by depleting CD4+ T helper lymphocytes. This weakens the immune system and allows opportunistic infections to manifest.

T lymphocytes are essential to the immune response and without them,

the body cannot fight infections or kill cancerous cells.

AIDS Diagnosis:

HIV positive

ARC (AIDS Relate Complex)

CD4+ T cell count below 200 per µL

In 1993, the CDC expanded their definition

of AIDS to include all HIV positive people

with a CD4+ T cell count below 200 per µL

of blood or 14% of all lymphocytes.

The AIDS diagnosis still stands even if,

after treatment, the CD4+ T cell count rises

to above 200 per µL of blood or other

AIDS-defining illnesses are cured.

Current treatment for HIV infection consists of highly active antiretroviral therapy, or HAART.

This has been highly beneficial to many HIV-infected individuals since its introduction in 1996 when the protease inhibitor-based HAART initially became available.

Current optimal HAART options consist of combinations (or "cocktails") consisting of at least three drugs belonging to at least two types, or "classes," of antiretroviralagents.

Standard goals of HAART include

improvement in the patient’s quality

of life, reduction in complications,

and reduction of HIV viremia below

the limit of detection, but it does not

cure the patient of HIV nor does it

prevent the return, once treatment is

stopped, of high blood levels of HIV,

often HAART resistant.

Moreover, it would take more than

the lifetime of an individual to be

cleared of HIV infection using

HAART.

Despite this, many HIV-infected individuals

have experienced remarkable

improvements in their general health and

quality of life, which has led to the

plummeting of HIV-associated morbidity

and mortality.

A prion is an infectious agent that is

composed primarily of protein.

The protein itself does not self-replicate

and the process is dependent on the

presence of the polypeptide in the host

organism.

The prion protein has been implicated in a

number of diseases in a variety of

mammals, including bovine spongiform

Encephalopathy (BSE, also known as "mad

cow disease") in cattle and Creutzfeldt-

Jakob disease (CJD) in humans.

All known prion diseases affect the

structure of the brain or other neural

tissue, and all are currently untreatable

and are always fatal.