Significant Viruses

Significant Viruses
Chapter 32
Microbiology for Surgical Technologists
Viruses
Are the smallest known form of life
Some believe that they are the oldest form of life and have influenced human evolution
May have donated many of our original genes
They can be deadly or simply an annoyance for a short period of time
Herpes Virus
Are very common among the animal population
Approx 100 strains have been identified
8 of which infect humans
The name is from the Greek Herpein, meaning “to creep”
It can remain dormant until conditions become appropriate for reactivation
Herpes Simplex Virus (HSV)
Divided into two types
HSV-1 – oral and/or occular lesions
HSV-2 – genital and/or anal lesions
Antibodies to HSV can be found in virtually every adult
Infection usually occurs in the first few years of life
HSV (continued)
Infection typically occurs through direct contact with lesions
As occurs with kissing or intercourse
The virus can be shed in the absence of a lesion
HSV-1 causes lesions on the mucocutaneous junctions of the nose or mouth
They live in the trigeminal ganglion
HSV-2 causes eruption around the genitals and/or anus
Live in the sacral ganglia
Recurrence of HSV-2 is more common than HSV-1
Can remain dormant for years between breakouts

Epstein-Barr Virus
Causes infectious mononucleosis (IM)
Called glandular fever
Or the kissing disease
Because it is acquired through close contact and exchange of saliva
Clinical diagnosis is made from the triad of fever, pharyngitis, and lymphadenopathy
Epstein-Barr Virus (continued)
Symptoms include:
Fever, malaise, splenomegaly, and hepatomegaly
The Paul-Bennell test (monospot) is used for diagnosis
There is only symptomatic treatment and observation of the spleen and liver to monitor for rupture
Enteroviruses
Very small viruses made up of RNA in a protein covering
Of the genus Enterovirus
Poliovirus
Eliminated from the Western Hemisphere by vaccination
The virus is transmitted by the fecal oral route
The virus initially grows in the oropharynx and their associated lymph nodes
The virus then moves to the gut mucosa where it multiplies and is shed in large numbers in the feces
Most infections are asymptomatic, but under certain conditions can spread to the CNS and cause paralysis
The virus can rise up the spinal cord to the medulla and brain stem requiring mechanical respiratory assistance
Polio
Iron Lung
Polio Ward
Respiratory Viruses
There are as many as 200 viruses that infect the respiratory system, but only seven cause major disease
The viruses pose significant threats to the very young or old and the immunocomprimised
Paramyxoviruses
Cause mumps and measles
Are important pathogen in children causing laryngotracheobronchitis (croup), bronchiolitis, and pneumonitis
Paramyxoviruses
Mumps
A common acute disease in children
Produces salivary gland inflammation
Spreads to the testes, ovaries, pancreas, and brain
Can cause sterility if contracted in adulthood
Mumps
Paramyxoviruses
Measles
Another acute childhood disease
Invades the lymphatic and respiratory systems
Prodromal stage produces fever and cough
Eruptive stage produces red spots
Influenza
There are three types: A, B, and C
A and B cause disease in humans
They are constantly mutating and require new vaccines to be created each year
This is called an antigenic shift and often results in local epidemics and global pandemics
The last major pandemic occurred in 1918 (called the Spanish Flu) killing 25 million people
Two other pandemics occurred in this century in 1957 and 1968
Scientists cannot predict when the next mutation will cause another pandemic
Flu symptoms include fever, cough, muscle aches, and chills
Most infections are self-limiting and do not require hospitalization
The very young, old and immunocomprimised are at greatest risk of complications
Hepatitis
HAV (HepA)
Primarily transmitted by the fecal-oral route
Also found in semen and blood
More prevalent in developing and third world countries than in US due to required vaccination of school children.
HBV (HepB)
Acquired Parenterally through blood transfusions and contaminated needles.
Causes jaundice, weakness, fever, and nausea
1 in 20 infections result in Chronic hepatitis
Persistent hepatitis six months after the onset of the illness
Chronic HBV can be benign with normal liver tests or may be an aggressive inflammatory process that can lead to cirrhosis (hardening of the liver).
The vaccine consists of three injections and is highly recommended for OR personnel.
Acquired parenterally and sexually
Mode of transmission is unknown in 20% of cases
Produces flu like symptoms without jaundice. Because the liver enzymes are not tested for these symptoms, the infection may not be detected for many years.
Chronic HCV occurs in 50-60% of cases, and most carriers remain contagious for life.
Many develop aggressive hepatitis and eventually cirrhosis and liver failure, requiring liver transplant.
HDV (Delta Virus)
Infects only those liver cells that are already infected with HBV.
Uses the HBV enzyms for replication and the acquisistion of a protein coat that allows it to survive outside of the liver
Those infected develop super infections that can be fatal, neither interferon or transplant is effective
HIV - AIDS
Although AIDS (acquired immunodeficiency syndrome) was discovered by the CDC in 1981, the virus that causes it, HIV, was not discovered until 1983
The chief routes of transmission are blood, sexual contact, and mother to child.
The main target cell for the virus is CD4 T lymphocytes (T-cells)
Of the 28 million that had HIV in 1997, it is estimated that 8 million will acquire AIDS. By 2000, 36 million were infected and to date approx 20 million have died.
Patients infected may be asymptomatic for many years before they are diagnosed with AIDS.
It weakens the immune system and allows opportunistic infections, malignancies and neurological diseases to occur.
Example: Kaposi’s sarcoma, lymphoma of the brain, Pheumocystis carinii pneumonia, etc.

Kaposi’s Sarcoma
HIV – AIDS (continued)
There is a new class of antiretroviral drugs that have been developed called protease inhibitors (PI) that inhibit the maturation and replication of the virus, but
AIDS is a fatal disease, there is no cure

Emerging Viral Infections
Chapter 33
Microbiology for Surgical Technologists
Emerging Viruses
Humans are more mobile now that ever before allowing for infections that were once localized to one area of the world to be spread throughout it
Most emerging viruses are zoonotic (animal host)
Emerging Viruses (continued)
Conditions that allow animal/human contact increase the chance for mutation of animal viruses so that they can infect humans
HIV is believed to have originated as a simian virus transferred to human through a primate bite
Hantavirus
Named for the area that it was discovered in: the Hantaan River in Korea
There are two members of the genus that cause disease
Hemorrhagic fever with renal syndrome (HFRS)
Hantavirus pulmonary syndrome (HPS)
The HPS strain is found in North and South America
The most prevalent strain is the Sin Nombre virus (SNV)
SNV is also known as the Four Corners virus
Named for the first outbreak where the borders of Utah, Colorado, New Mexico, and Arizona meet
The disease is contracted by breathing in the virus from the infected urine and feces of deer mice
This can be done by sweeping or vacuuming in areas the the deer mice have been
The primary manifestation of the disease are flu like symptoms
Followed by the lungs filling with water from the circulatory system resulting in respiratory distress
Death occurs in 2/3 of the cases
Viral Hemorrhagic Fevers
All share common characteristics
High fever, headache, myalgia, diarrhea, vomiting, and internal hemorrhaging
Because of their horrible nature, they cause fear throughout the world
With global mobility, it is only a matter of time before an outbreak occurs in this country
Ebola Hemorrhagic Fever
Was first recognized as an emerging viral infection in 1976
Was named for a river in the Democratic Republic of the Congo (formerly Zaire)
The host for this virus is unknown, it is believed to be zoonotic
It is not carried by humans
Is a fatal viral disease that affects humans and primates
It is a member of the Filoviridae family
Replicate rapidly and infect multiple organs through the bloodstream
As these structures deteriorate, uncontrolled bleeding occurs
Especially in the mucosa, abdomen, and pericardium
Death comes from decreased blood volume causing shock and respiratory failure
Usually manifests as sporadic outbreaks
Spread by person to person contact, with a high nosocomial infection rate
When appropriate medical supplies, quarantine and sterilization is incorporated, the outbreaks are controlled
Surgical Implications
STSRs are frequently exposed to blood-borne pathogens
Vaccination for HBV is strongly recommended
Universal precautions should be used on all surgical procedures
All surgical patients should be treated as if they are infected
Protective eyewear should be worn in all cases, it is an OSHA requirement
Double gloving is recommended to help prevent needle sticks
Always wear gloves when handling contaminated items
Needles should not be recapped to prevent needle sticks

Words of Wisdom
The learning process is never-ending, and growth will continue if only you will allow it to.
Arlene Francis