Microbiology: Viral Disease

viruses

smallest agents able to cause disease in living things

virion

complete virus outside its host cell cannot replicate independently, but within the cell the virus utilizes the metabolism of the cell and produces copies of itself often destroying the cell.

Replication inside a host cell leads to the release of virus particles called Virions.

what are all viruses considered?

obligate intracellular parasites and are absolutely dependant on a host cell for their replication.

Viruses

•The genetic information in the virion is either RNA or DNA and is responsible for determining its replication pathway and hence a major consideration when classifying viruses.

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Guillain barre syndrome

•disorder in which the body's immune system attacks part of the peripheral nervous system.

•The first symptoms of this disorder include varying degrees of weakness or tingling sensations in the legs.

•These symptoms can increase in intensity until the muscles cannot be used at all and the patient is almost totally paralyzed.

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reye's syndrome

•deadly disease, strikes swiftly and can attack any child, teen, or adult without warning.

- disease which affects all organs of the body, but most lethally the liver and the brain

- two-phase illness because it is almost always associated with a previous viral infection, such as influenza, cold, or chicken pox.

what causes Reye's syndrome?

may be links between eye's and ASA meds

what organs does Reye's syndrome lethally affect?

liver and brain

adenovirus

most common lower respiratory tract disease affecting infants and children under 2

RSV

what kind of virus is RSV?

enveloped RNA virus

how is RSV transmitted?

respiratory droplets

where in the body does RSV take place?

bronchioles and air sacs of the lungs and is aka viral pneumonia

RSV treatment for infants with severe infection?

ribavirin

whats the major cause of common cold?

rhinovirus

where does rhinovirus thrive?

human nose

how is rhinovirus transmitted?

via droplets and direct contact

rhinovirus treatment?

no tx or vaccine

rhinovirus characterization?

picornavirus family containing over 100 different RNA viruses

SARS (severe acute respiratory syndrome)

single strand RNA virus from coranaviridae class

where does SARS have a major outbreak?

china, honk kong, taiwan, canada, and singapore

SARS prodromal symptoms are similar to which other virus?

influenza

what happens to patients with SARS after 2-7 days?

may lead to severe respiratory illness about 10-20% needing intubation

most common dermotropic viral disease?

herpes

herpes characterization?

double stranded DNA virus from herpesvirus family

how is herpes transmitted

•passes among cells by intracellular bridges and remains in the nerve cells until something triggers it to multiply.

Lipschutz bodies

Granules in the nucleus of cells infected by herpes simplex virus

herpes type 1

appear above the waist ie. Cold sores or fever blisters which involves the lips, gums and nose. Gingivostomatitis which involves the oral mucosa, tongue and cheeks. Herpes Keratitis which involves the eyes and is important cause of blindness. Herpes encephalitis which involves the brain and associated with convulsion and may lead to death.

herpes type 2

•appear below the waist ie. Genital herpes.

•In the majority of cases symptoms usually reappear often in response to stressful triggers such as sunburn, fever, menstruation or emotional distress.

how is herpes type 1 transmitted

saliva, birth canal, vesicular fluid

how is type 2 herpes transmitted?

sexual contact

herpes treatment

Herpes Keratitis- Idoxuridine (IDU)

Rifluridine

Encephalitis- Vidarabine

Genital Herpes- Acyclovir (Zovirax)

varicella chicken pox caused by?

•double stranded DNA virion from the Herpesvirus family.

varicella transmission

via respiratory droplets and contact with vesicular fluid

varicella characterization?

teardrop shaped fluid-filled vesicles.

varicella complications

as Reye syndrome (associated with the use of aspirin during the acute phase of infection), Pneumonia, encephalitis and bacterial skin infection

varicella treatment

Acyclovir

herpes zoster [shingles] caused by

adult disease caused by same varicella disease

(people who had chickenpox when they're little, the virus never goes away and they can get this)

herpes zoster virus

•virus multiply in the ganglia along the spinal cord and travel down the nerve to the skin of the body trunk where they cause blisters.

herpes zoster symtoms

headaches as well as facial paralysis and sharp ice-pick pains along a dermatone of the head and face.

who is most susceptible to herpes zoster?

old and immunocompromised

herpes zoster treatment

varicella immune globulin

what does the herpes zoster rash look like?

follows the dermatome path

measles (rubeola) caused by

RNA virus in paramyxovirus family

rubeola transmission

droplets

rubeola symptoms

•hacking cough, sneezing, nasal discharge, eye redness and high fevers.

koplik spots in PE

what does the rash in measles look like?

•Red patches with white grain like centers appear along the gum line in the mouth called Koplik spots, then the rash appears which are maculopapules.

•Within one week the rash disappears with complete recovery of the disease.

measles complications

•rare but may develop including bacterial diseases of the lungs, because of damaged respiratory tissue or Subacute Sclerosing panencephalitis (SSPE) which is rare brain disease characterized by loss of nervous function and cognitive skills.

•Vaccines are composed of live attenuated virus (MMR).

rubella (German measles) viral family

•RNA virus in the Togavirus family.

rubella transmission

respiratory droplets

rubella symptoms

•occasional fever with a variable pale-pink maculopapular rash beginning in the face and spreading to the body and extremities

•Recovery is prompt, rash fades after 2 days, but relapses appear to be more common than with other diseases because the virus remain active within the body cells.

•The disease is dangerous to pregnant women which may cause congenital rubella syndrome to the fetus which may cause cataracts, glaucoma, deafness and heart defects.

fifth disease (erythema infectiosum) viral family

•strain of Parvovirus designated B19, also known as B19 infection.

It is a small DNA virion.

fifth disease transmission

droplets

who does fifth disease mc affect

children

fifth disease characterization and sx

•a fiery red rash on the cheeks and ears, also known as slapped-cheek disease.

•The rash may spread to the trunk and extremities, butfades within several days.

how can fifth disease be caused in adults

arthalgias

fifth disease treatment

none, no vaccine

mumps viral family

RNA virion from the paramyxovirus family

mumps transmission

Resp. droplet, direct contact, fomite

where can mumps virus be found?

in human blood, urine and CSF

what area does mumps most primarily affect?

parotid glands

mumps symptoms

•observed primarily in the parotid glands.

•Obstruction of the ducts leading from the glands retards the flow of saliva, which cause the characteristic swelling.

•In males the mumps virus may pose a threat to the reproductive organs. Swelling and damage to the testes called orchitis, may be a complication.

•The sperm count may become reduced, but sterility is not common.

smallpox (variola) viral family

•RNA virus of the Poxvirus family.

variola transmission

skin lesions and the respiratory tract.

variola symptoms

Early signs are high fever and generalized weakness. Pink-red spots called macules soon follow which change to pink pimples or papules then to fluid-filled vesicles. The vesicles become deep pustules which break open and emit pus

molluscom contagiosum viral family

DNA virion poxvirus

molluscom contagiosum transmission

•direct contact with the lesions and sexual contact.

molluscum contagiosum symtoms

•Is a viral disease accompanied by wart like skin lesions.

•The lesions are usually flesh toned and appear in the facial skin and eyelids in children and external genitalia in adults.

•Lesions are removed by excising them.

viscerotropic viral disease affect which organs?

viral disease that blood, liver, spleen , small and large intestine

whats the first human disease associated with a virus?

yellow fever

yellow fever causative agent?

RNA virion Flavivirus

yellow fever is often referred to as?

arbovirus because it is an arthropod borne

where does yellow fever have an endemic in?

africa and South America

how can a yellow fever epidemic occur?

person is bitten by an infected mosquito in the forest, who then travels to urban areas where the virus is passed via a blood meal to another mosquito species "Stegomya Aegypti"

where can yellow fever occur?

- occur in nature in monkeys and jungle animals where the virus can be transmitted by mosquitos

how is yellow fever transmitted

from human to human by the mosquito Aedes aegypti, or from infected monkeys to humans by the mosquito Haemagogus

how does yellow fever cause liver infection?

•Mosquitoes inject the virus into the bloodstream and fever mounts within days.

Infection of the liver causes an overflow of bile pigments into the blood causing jaundice. The gums bleed, the stools turnbloodyand the delirious patient often vomits blood. Patients usually die of internal bleeding caused by coagulation defects

is there a yellow fever vaccine?

effective live virus vaccine for those traveling

Aedes aegypti mosquito causes?

a parasite t that is a vector for dengue fever and yellow fever

dengue fever viral family

RNA virion of flavivirus family

how does the dengue fever virus work

multiples in the WBC and platelets of human blood

dengue fever transmission

•Aedes aegypti mosquito and by the tiger mosquito Aedes albopictus.

dengue fever characterization and symptoms

high fever followed by sharp pain in the muscles and joints. Patients report a sensation that their bones are breaking why is sometimes called breakbone fever.

dengue hemoorhagic fever

In one strain of the virus the condition causes a rash from skin hemorrhages on the face and extremities. Severe shock and vomiting ensues as well as hypotension

infectious mononucleosis transmission

kissing disease, because it is spread via saliva. Droplets and fomites such as table utensils and drinking glasses may also carry the virus.

Epstein barr virus

infectious mononucleosis type of herpes virus

infectious mono symptoms

•Characterized by enlargement of the lymph nodes, sore throat, fever, spleenomegally and a high count of damaged B-lymphocytes.

•runs 3-4 wks and those who recover usually become carriers for several months and shed the viruses into the saliva.

how is mono diagnosed

•Detection of elevated lymphocyte count with observation of Downey cells (damaged B-lymphocytes with vacuolated and granulated cytoplasm).

what are downey cells?

**damaged B lymphocytes found in mono

how is mono detected

**monospot slide test to detect heterophiles antibodies

what is hepatitis

•This infection is characterized as an acute inflammatory disease of the liver caused by several viruses.

hepatitis A AKA

infectious hepatitis

Hep A viral family

small RNA virion to piconarvirus family

hep A transmission

•food and contaminated water by feces of an infected individual. Can also be transmitted by raw shellfish such as clams and oysters, since these animals filter and concentrate the viruses from contaminated seawater. Sexual contact is also another mode of transmission.

how ling is Hep A incubation

2-4 wks

which hepatitis is AKA as short incubation hepatitis?

Hep A

Hep A sx

anorexia, nausea, vomiting, low grade fever and discomfort in the right upper quadrant as the liver enlarges.

how is Hep A diagnosed?

on liver function tests, observation of characteristic symptoms and demonstration of hepatitis A antibodies in the serum.