Final

• A. Viruses are minute parasitic particles consisting of DNA or RNA genomes packaged within a protein capsid; they invade host cells and appropriate the cell’s machinery for mass production of new virions, both in cytoplasm and nucleus; viruses exit the host cell by lysis or budding; budded viruses leave with an envelope; actively infected host cells are usually destroyed.
• B. Viruses attack a variety of host and cell types; individual viruses are relatively host/cell specific, due to the need for receptor recognition; target cells include nervous system, blood, liver, skin, and intestine.
• C. Diseases range from mild and self-limited to fatal in effects; symptoms are local, systemic, and depend on the exact tissue target; identification and diagnosis are by culture, microscopy, genetic probes,and serology; immunity is both humoral and cell-mediated; limited number of drugs available for treatment.
• D. DNA and some RNA viruses persist in inactive state (latent) in host cells; some latent viruses cause recurrent infections, and others integrate into host genome and cause cancerous transformation; some viruses are teratogenic and cause congenital defects; zoonotic viruses transmitted by vectors cause severe human
• Smallest parasites composed of dna and rna surrounded by protein capsid and contains spikes that have specific receptor sites. They take over the cell and exit by lyses or budding leave with envelope host cell destroyed. Specific target of host cells

• Parvoviruses have single stranded DNA - causes respiratory distress in children- non enveloped
• Single-Stranded DNA Viruses: Parvoviruses are the tiniest viruses, genome size
• cause severe disease in several mammals; cats, dogs and puppies
• human parvovirus (B19) causes erythema infectiosum
• a mild respiratory infection of children that can be dangerous to fetus.
• Children may have fever or rash on cheeks
• Severe fatal anemia if woman transmits virus to fetus

• Nonenveloped, dsDNA30 types associated with human disease
• Infect lymphoid tissue, respiratory and intestinal epithelia and conjunctiva
• Oncogenic in animals, not in humans
• Spread by respiratory and ocular secretions
• Causes colds, pharyngitis, conjunctivitis, keratoconjunctivitis, acute hemorrhagic cystitis
• Severe cases treated with interferon
• Inactivated polyvalent vaccine

• Varicella-Zoster Virus (VZV)Causes chickenpox and shingles
• Humans only natural host
• Transmitted by respiratory droplets and contact
• Primary infection – chickenpox – characteristic vesicles
• Virus enters neurons and remains latent
• Later, reactivation of the virus results in shingles with vesicles localized to distinctive areas, dermatomes
• More common in older patients
• Treatment: treat symptoms in uncomplicated infections; acyclovir, famciclovir, interferon for systemic disease
• Live attenuated vaccine for chickenpox and shingles

Varicella-Zoster Virus (VZV): This herpesvirus causes both chickenpox (varicella) and shingles (zoster); chickenpox is the primary infection, zoster is later recurrence of infection by latent virus. Chickenpox is transmitted through droplets; symptoms are fever, poxlike papular rash. In zoster, the virus has migrated into spinal nerves and is reactivated by surgery, cancer, or other stimuli; causes painful lesions on skin of trunk or head; severe disease treated with acyclovir or famciclovir; immune globulin used to relieve symptoms; vaccine now available. Humans are the only host, causes both chicken pox and shingles (herpes zoster )is a reactivation of a latent varicella virus, the virus harbors in the respiratory tract.

• They may become infected with macular, popular vesicular rash on face and trunk.
• Becomes dormant in the latent ganglia of nerves.
• Early symptoms of shingles are:Acute pain in the nerve root
• Redness of the dermatome
• Vesicular-papular rash on the chest and back that is asymmetrical and does not cross the midline of the body

It can be caused by X-ray treatments, immunosuppressive and other drug therapy, surgery, or developing malignancy, declining immune function in older patients.

• Cytomegaloviruses – CMV Produce giant cells with nuclear and cytoplasmic inclusions
• Transmitted in saliva, respiratory mucus, breast milk, urine, semen, cervical secretions
• Commonly latent in various tissues
• Most infections are asymptomatic3 groups develop a more virulent form of disease: fetuses, newborns, immunodeficient adults

• Fetuses, newborns, AIDS patients, transplant patients, perinatal CMV infection, immunodeficient adults
• Treatment reserved for immunocompromised – ganciclovir, foscarnet

Sore throat, high fever, and cervical lymphadenophaty and lymphocytosis, which develop after 30-50 day incubation period, may have a grey-white exudates in the pharynx a skin rash and a enlarged liver and spleen.

• Syndrome characterized by fever and lymphocytosis
• Patients undergoing kidney transplants and half of those receiving bone marrow develop
• CMV pneumonitis, Hepatitis, Myocarditis, Meningoencephalitis, Hemolytic anemia, Thrombocytopenia
• Severe opportunistic infection for AIDS patients->
• Symptoms are-Overwhelming systemic disease-Fever-Sever diarrhea-Hepatitis-Pneumonia-High mortality-Invasion of retina can lead to blindness

• Paramyxoviruses: Nonsegmented genome; glycoprotein spikes facilitate development of multinucleate giant cells; are spread through droplets.
• 1. Paramyxovirus causes parainfluenza, a common, mild form of influenza or coldlike illness, mostly in children; mumps or parotitis, inflammatory infection of salivary glands, sometimes testes; occurs
• often in children; can cause deafness; prevented by live, attenuated vaccine (MMR).

Clinical disease is marked by respiratory symptoms, fever, aches, sore throat; secondary pneumonia is frequent cause of death; long-term complications are Guillain-Barré syndrome and Reye syndrome; controlled with anti-flu drugs and vaccination. fever, headache, myalgia, pharyngeal pain, shortness of breath, and repetitive bouts of coughing.

• Laryngotracheobronchitits - Croup caused by parainfluenza
• Most common in infants and younger children

• Widespread as influenza but more benignRespiratory transmission
• Seen mostly in children
• Minor cold, bronchitis, bronchopneumonia, croup
• No specific treatment available; supportive therapy
• Paramyxovirus causes parainfluenza, a common, mild form of influenza or coldlike illness, mostly in children; mumps or parotitis, inflammatory infection of salivary glands, sometimes testes; occurs often in children; can cause deafness; prevented by live, attenuated vaccine (MMR). spread by respiratory droplets, causes minor upper respiratory symptoms. Leads to cold to bronchitis to bronchopneumonia and croup.

• Influenza A Attatches to and multiplies in the cells of the respiratory tract
• Neuraminidse - breaksdown the membrane
• Hemagglutinin -attaches to respiratory mucosal receptors.

• Also calledPneumovirus, or respiratory syncytial virus (RSV)
• causes croup, an acute respiratory syndrome in newborns that is a problem in hospital nurseries
• treated with aerosol ribavirin.
• children 6months and younger are very susceptible, nose and eyes are portals of entry
• symptoms- fever, rhinitis, pharyngitis, and otitis.
• It is the most prevalent respiratory infection for age group.

• Relatively large RNA viruses with distinctively spaced spikes on their envelopes
• Common in domesticated animals
• 3 types of human coronaviruses have been characterized:HCV causes a cold
• An enteric virus
• Severe Acute Respiratory Syndrome (SARS)
• Airborne transmission
• 9% of cases fatal-
• Also viral pneumonia, myocarditis and human enteric infections

• Rhinovirus: Most prominent cause of common cold; spread by droplets; confines itself to respiratory membranes; virus exists in over 110 forms; symptoms are nasal drainage, cough, sneezing, sore throat;
• treatment is symptomatic.

Caused by the corona virus . Origin is from Asian fruit bat, symptoms-fever over 100, body aches, , classical respiratory symptoms, and severe cases can result in respiratory distress and death.

Picornaviruses are the smallest human viruses. Nonenveloped RNA Viruses

Poliovirus, cause of polio; virus can spread through close contact, contaminated food, water; occasionally leads to paralysis caused by infection and destruction of spinal neurons; bulbar type requires life support; disease controlled through vaccination with inactivated polio vaccine (IPV) and oral polio vaccine (OPV).Caused by the picornavirus infected through food, water, hands, objects contaminated with feces and mechanical vectors. It is a naked capsid that is resistant to acid, bile and detergents- has receptors in or pharynx and intestines. Mostly effects children.

• Rotavirus, the cause of severe infantile diarrhea; most common cause of viral enteric disease worldwide; children can die from effects of diarrhea, dehydration, shock.
• Fomits. Rotavirus is the only double-stranded RNA virus and a common cause of viral gastroenteritis.

Double-Stranded RNA Viruses Reoviruses: Most important one is Rotavirus, the cause of severe infantile diarrhea; most common cause of viral enteric disease worldwide; children can die from effects of diarrhea, dehydration, shock. Rotavirus- non-enveloped rna virus associated with reovirus.

• Herpesviruses: Persistent latent viruses that cause recurrent infections and may be involved in neoplastic transformations; attack skin, mucous membranes, and glands. a. Herpes simplex virus (HSV): Types 1 and 2 both create lesions of skin and mucous membranes; migrate into nerve ganglia; are reactivated; cause disseminated disease in newborn infants and immunodeficient patients; cause whitlows on fingers of medical and dental personnel. HSV-1 is transmitted by close contact and droplets and mainly infects lips (cold sores, fever blisters), eyes, and oropharynx. HSV-2 is
• sexually transmitted and usually affects the genitalia. Complication in newborns infected at birth with either virus is encephalitis. Infections are treated with some form of cyclovir; controlled by barriers and care in handling secretions.

Herpes 1, some general properties about this, where can it live, transmitted, symptoms-fever blisters, cold sores… vesicles crop up on or around the lips. A few hours of tingling or itching precede the formation of one or more vesicles at the site lasting 2-3 days gone in week- Transmitted via close contact- usually occurs in infants and early childhood-lives in the ganglion of the 5th cranial nerve- 30% affect cns.

Transmission by sexual contact, starts with malaise, anorexia, fever, and bilateral swelling and tenderness of the groin. Then intensely sensitive vesicles break out in clusters on the genitalia, recurrent outbreaks by triggers. Usually age 14-29-one of the most common std-lives in ganglion of lumosacral spinal nerve- causes gynecological and obstetrical problems.. Also causes whitlow infected finger and encephalitis.

• A common complication in adolescents is pharyngitis, a syndrome marked by sore throat, fever, chills, swollen lymph nodes and difficulty in swallowing. Children get gingivostomatitis, which affects the gum,
• tongue and soft palate

Vesicles and exudate are typical diagnostic symptoms, scrapings from base of lesions showing giant cells, culture and specific tests for diagnosing severe or disseminated HSV; direct fluorescent antibody tests Treatment: acyclovir, famciclovir, valacyclovir; topical medications

• Becauseof the changing nature of the antigens on the viral surface, annual vaccination is considered the best way to avoid infection
• Anyone over the age of 6 months can take the vaccine
• It is a live vaccine
• Especially recommended for high-risk groups
• May cause patient to manifest flu symptoms
• A serious complication of the vaccine is the Guillain-Barre Syndrome
• A neurological condition that can affect 1 in 100,000 recipients
• Autoimmune response that leads to demyelination of PNSDebilitating and fatal
• Intramuscular
• New form is through inhalation
• FluMist – nasal mist vaccine

• Caused by Morbillivirus
• Also known as red measles and rubeola
• Different from German measles
• Very contagious; transmitted by respiratory aerosols
• Humans are the only reservoir
• Less than 100 cases/yr in U.S.; frequent cause of death worldwide
• Virus invades respiratory tract
• Sore throat, dry cough, headache, conjunctivitis, lymphadenitis, fever, Koplik spots – oral lesions Exanthem

• Arboviruses: Viruses Spread by Arthropod Vectors
• Mosquitoes, ticks, flies, and gnats
• 400 viruses
• Togaviruses, flaviviruses, some bunyaviruses and reoviruses
• Most illnesses caused by these viruses are mild fevers; some may cause severe encephalitis, and life-threatening hemorrhagic fever