MICRO Ch 18 - Viral Infections of Humans

3 Herpes Complexes?

1. Herpes simplex 1 2. Herpes simplex 2 3.Varicella - Zoster HHV 3

What is the timeline for infection with these sores?

8-10 days from eruption to resolution. May be suppressed with antivirals.

Varicella-Zoster

A DNA virus which is also known as human herpes virus 3. Transmission is from person to person by direct contact or droplet or airborne spread of vesicle fluid, or secretions of the respiratory system of persons with chicken pox.

Hep E Hepatitis

A nonenvelopped, ssRNA virus, family Calciviridae. Fecal-oral transmission, primarily via fecally contamined drinking water; also person to person. No evidence of chronic form. Children are asymptomatic, usually benign and self limiting, but the condition can become worse with age.

Reye (Rize) Syndrome

A severe encephalomyelitis with liver damage that may follow clinical chicken pox is aspirin is given to a child younger than 16.

Dysentery

A severe form of diarrhea may also be caused by various pathogens including bacteria and protozoa. Causes severe dehydration.

Type A Hepatitis

A single stranded RNA virus. Transmitted fecal-oral transmission, person to person; infected food handlers; fecally contaminated foods and water. Abrupt onset; varies in clinical severity from a mild illness lasting 1-2 weeks to a severe, disabling disease lasting several months; no chronic infection. Most people recover without treatment.

Type G Hepatitis

A ssRNA virus in the family Flaviridae. Parenteral transmission. Can cause chronic hepatitis. Coinfection with Hep B, C and HIV. Not many symptoms like hepatitis. May slow the progression of HIV to AIDS, don't know why.

AIDS

AIDS is.a severe, life threatening syndrome that represents the late clinical stage of infection with HIV. Affects the body by invasion and destruction of helper T cells leads to suppression of the patient's immune system (immunosuppression) (this is the mechanism the HIV virus uses to cause AIDS).

Adenoviruses cause which eye diseases?

Acute viral diseases of one or both eyes, associated with inflammation of the conjunctiva, edam of the eyelids and periorbital tissue, pain, photophobia and blurred vision.

Chicken pox

Acute, generalized viral infection, with fever and a skin rash. Mild, self limiting but can severely damage a fetus (complications include pneumonia, secondary bacterial infections, encephalitis). Chickenpox is the leading cause of vaccine-preventable death in the United States.

How are the measles transmitted?

Airborne transmission occur by droplet spread and direct contact with nasal or throat secretions of infected persons or with articles freshly soiled with nose and throat secretions.

What are cold sores? What causes them?

Also known as fever blisters. Usually caused by Herpes simplex 1, but can be caused by herpes simplex type 2 .Viruses target the mucous membranes. Virus is living in the sensory neuron of the dorsal root ganglion when dormant. When active, they become cold sores.

Describe the common cold

Can be caused by ~200 different viruses. One cold can't protect us from the other. Symptoms include sore throat, sneezing, a runny nose, nasal congestion and sometimes a headache. Occasionally muscle aches and fatigue. There is no vaccine for protection.

Why is rubella so dangerous for women in the 1st trimester of pregnancy?

Can cause congenital Rubella syndrome, could lead to intrauterine death, spontaneous absorption, or congenital malformations.

How are genital warts transmitted?

Caused by Human papilloma viruses (HPV): DNA viruses. Transmission occurs via infected humans by direct contact, usually sexual. Genital warts can become malignant.

Hemorragic Conjunctivitis

Caused by adenoviruses and enteroviruses. this viral disease has sudden onset, with redness, swelling and pain in one or both eyes. Small discrete subconjunctivial hemorrhages may enlarge to form confluent subconjunctivial hemorrhages.

Hantavirus Pulmonary Syndrome (HPS)

Caused by at least five different hantavirus (Sin Nombre, Bayou, Black Creek, Canal, New York - 1, Monongahela) Transmission occurs via inhalation of aerosolized rodent feces, urine and saliva. No person to person transmission. Characterized by fever, Myalgias, GI complaints, cough , difficulty breathing and hypotension (decreased blood pressure).

Viral Hemorrhagic Diseases

Caused by many different diseases, including dengue virus, yellow fever virus, Crimean-Congo hemmoragic virus, Lassa virus, Ebola virus. Infected humans serve as resevoirs. Transmission is person to person via direct contact with infected blood, secretions, internal organs or semen. Symptoms: sudden onset, headache, followed by pharyngitis, vomiting, diarrhea, rash and internal hemorrhaging.

Viral meningitis

Caused by many different viruses. Sudden onset of febrile illness with signs and symptoms of meningeal involvement. CSF has mononuclear WBC, increased protein but no bacteria.

Mumps

Caused by mumps virus, an RNA virus. Characterized by fever, swelling, tenderness of the salivary glands. Complications can include orchititis (swelling of the testes) oopheritis (inflammation of the ovaries), meningitis, encephalitis, deafness etc. We are vaccinated against mumps.

Poliomyelitis

Caused by polio viruses- RNA viruses. Transmission is person-to person, primarily via the fecal-oral route; also throat secretion. Causes mild illness in most, with fever, malaise, headache, nausea, vomiting. In 1% the disease progresses to severe muscle pain, stiffness of the neck and back, with or without flaccid paralysis.

Rabies

Caused by rabies virus; a bullet shaped, enveloped RNA virus. Many reservoirs, wild animals. Transmission occurs via the bit of a rapid animal which introduces virus-laden saliva; airborne transmission from bats also occurs. Usually fatal. Causes acute encephelomyelitis, mental depression, headache, fever, malaise, paralysis, spasm of throat muscles, fever, malaise, paralysis, spasm of throat muscles, convulsions, death by respiratory failure.

Influenza

Caused by several viruses. Protection is gained from individual strains. Symptoms include high fever and chills, cough, head ache, muscle aches, and extreme fatigue. Occasionally sore throat, runny nose, vomiting, diarrhea. Vaccines offers some protection.

What causes the symptoms of a viral infection?

Cell destruction leads to most of the symptoms of a viral infection, which may vary depending on the location.

Why is small pox so dangerous?

Contagious before outbreak of rash!

Variola Major/Minor - Small pox

Double stranded DNA enveloped. Humans are the only known source, droplet spread or skin inoculation. Systemic viral infection with fever, malaise, headache, prostration, severe back ache, a characteristic skin rash and occasional abdominal pain and vomiting. Rash looks similar to chicken pox. Can become severe with bleeding into the skin and mucous membranes, followed by death.

What are anogenital herpes viral infections?

Genital herpes. Usually caused by HSV-2; occasinally by HSV-1. In males, sores are found on the penis of anus. In females, sores are found on the cervix, vulva, legs, buttocks.

Type C Hepatitis

HCV, an enveloped, ssRNA virus in the family Flaviviridae. Primarily parenterally transmitted (though bodily fluids, into bloodstream), rarely sexually transmitted. Usually an insididious onset; 50-60% of patients develop a chronic infection; may lead to cirrhosis or hepatocellular carcinoma.

Type B Hepatitis

Hepatitis B Virus - an enveloped dsDNA virus in family Hepadnaviridae; the only DNA virus that causes hepatitis. Transmitted by sexual or household contact with an infected person; mother to infant before birth; infant drug use; tattooing; needle-sticks and other types of healthcare associated transmission. Usually has a gradual onset, severity ranging form unapparent cases to fulminating, fatal cases; chronic infections occur, jaundice is typical, may lead to cirrhosis or heptaocellular carcinoma.

Type D Hepatitis

Hepatitis D virus - an enveloped, ssRNA, viral satellite; in the genus Deltavirus. Exposure to infected blood and body fluidsl contaminated needles; sexual transmission; coinfection with HBV is necessary. Usually has an abrupt onset; may progress to a chronic and severe disease. Also transmitted by the Hep B Vaccine

Shingles (also known as Herpes Zoster)

Inflammation of sensory ganglia of cutaneous sensory nerves, producing fluid filled blisters, pain, and paresteisia (numbness and tingling). Shingles may occur at any age, but most commonly after the age of 50.

Hepatitis

Inflammation of the liver, can have many causes, including alcohol, drugs or viruses. Typical signs and symptoms include liver necrosis, hepatomegaly, jaundice, billirubinemia. Hepatitis can also occur as a result of viral diseases such as infectious mononucleosis, yellow fever and cytomegalovirus infection.

Flaccid Paralysis

Loss or impairment of motor function in a part due to a lesion of neural or muscular mechanism.

Diarrhea

May or may not be caused by an infectious disease. May be caused by a virus, a bacterium, a protozoan or a helminth.

Latency of herpes?

Means that the condition comes and goes. When it is active or dormant depends on a number of factors including stress and illness.

Fatality rate of small pox?

Minor small pox 1% Major small pox 20-40%

How is HIV diagnosed?

Most HIV infected patients develop detectable antibodies within 1-3 months after infection. The most commonly used screening test is an enzyme-linked immunosorbent assay ELISA. If the screening test is positive, a Western blot analysis is preformed. Quantitative assessment of "viral load" is used to monitor the effectiveness of antiviral therapy.

How are we extending the lives of Patients with HIV?

Previously considered to be a universally fatal disease, certain combinations of drugs, referred to as cocktails, are extending the lives of some patients with HIV.

Measles (Rubeola)

RNA virus in the family Paramyxoviridae. Acute, viral highly communicable viral disease with fever, conjunctivitis, cough, photosensitivity, Koplik spots in the mouth, and red blotchy skin rash. The rash begins on the face during days 3 to 7 and then becomes generalized. Complications include bronchitis, pneumonia, otitis media and encephalitis.

What is the major cause of the common cold?

Rhinovirus (more than 100 serotypes).

Examples of cold causing viruses?

Rhinovirus, coronavirus, parainfluenzavrisus.

German measles (Rubella)

Rubella is caused by rubella virus, an RNA virus in the family Togoviridae. Mild, febrile viral disease. A fine, pinkish, flat rash begins 1 or 2 day after the onset of symptoms. The rash starts on the face and neck and spreads to the trunk, arms and legs.

SARS

Severe acute repiratory syndrome is caused by corona virus, ssRNA, enveloped. Causes high fever, chills, headache, a general feeling of discomfort, body aches and sometimes diarrhea. Most patients develop dry cough followed by pneumonia. Transmission occurs via infected individuals by respiratory droplets, or by touching the mouth, nose or eye after touching an infected object.

Influenza viruses, type A, B and C

Single stranded RNA viruses. Causing an acute, viral respiratory infection. Transmission is via infected humans; pigs and birds also serve as reservoirs. Spread by airborne secretions or direct contact.

H1N1

Swine flue. Novel Influenza A virus. Transmission, droplet and direct contact. Causes flu like symptoms. Fever, cough, sore throat, body aches, headaches, chills and fatigue.

Viral Gastroenteritis

The most common viruses infecting children in their first years of life. Viruses infection children and adults include noravirus-like viruses and rotaviruses. Symptoms include nausea, vomiting, diarrhea, abdominal pain, myalgia, heasache, malaise and a low-grade fever. There is currently a vaccine in development for rotavirus. In addition, breast milk contains an antibody against rotavirus.

Signs and symptoms of HIV?

The signs and symptoms of acute HIV infection usually occur within several weeks to several months after infection with HIV. Initial symptoms include an acute, self-limited mononucleosis like illness lasting 1 or 2 weeks.

What do the papilloma viruses cause?

There are at least 70 different types of sexually transmitted human papillomaviruses (HPV). They are DNA viruses transmitted by direct contact. Produces warts.

Human Immunodeficiency deficiency Virus (HIV)

There are two types of HIV, type 1 and HIV-2; ssRNA viruses retrovirus. Transmission occurs via infected humans, by direct sexual contact; contaminated needles/syringes; transfusion of contaminated blood; transplacental transfer from mother to child, broken glass injuries etc.

Avian Influenza virus type

Three prominent subtypes - H5, H7 and H9. Bird to human transmission occurs via contact with infected poultry of contaminated surfaces. Transmission is person to person. In humans, the virus causes respiratory infection with manifestations raging from influenza-like symptoms (fever, cough, sore throat, and muscle aches) to eye infections, pneumonia, acute and severe respiratory destress, and other severe and life threatening complications.

How is herpes transmitted?

Transmission is from direct contact when legions are present, including during childbirth for one infected with genital herpes.

How are german measles transmitted?

Transmission occurs by droplet spread or direct contact with nasopharyngeal secretions of infected people.

Monkey pox virus

Transmission occurs via animal bite or contact with an infected animal's blood, body fluids or rash. Person to person transmission does not occur. Rare viral disease causes fever, headache, muscle ache, lymphadenitis, malaise, and a rash. Rarely fatal.

How is viral gastroenteritis transmitted?

Transmission occurs via infected humans, most often by way of the fecal oral route; possibly from contaminated water and shellfish.

Transmission of the common cold?

Transmission occurs via respiratory secretions by way of hands and fomites or direct contact with or inhalation of airborne droplets .

Vaccines for Hepatitis?

Vaccines are available for HAV and HBV. The HAV vaccine contains inactivated virus grown in cell culture, is recommended for people at increased risk of acquiring Hep A. The HBV vaccine is a subunit vaccine, produced by genetically engineered Saccharomyces cerviciae. HBV vaccine is routinely administered to US children. It is required for healthcare workers exposed to blood.

How is the common cold transmitted?

Via respiratory secretions by way of hands and fomites or direct contact with or inhalation of airborne droplets.

Arboviruses

Virus transmitted by Arthropoda.

Infectious mononucleosis

caused by the Epstein-Barr virus, which is also known as HSV 4, Transmision occurs via infected humans, direct contact with saliva. May be asymptomatic, or may be characterized by sore throat, lymphadenopathy, splenomegaly, enlarged spleen, and fatigue. EBV is shown to be oncogenes.