Week 9 Flashcards
Measles
Measles (rubeola or 7-day measles) affects susceptible children as an
acute, highly infectious epidemic disease.
How does the measles virus enter?
enters the nose and throat by airborne transmission
What are the first signs of measles?
nasal discharge and redness of the eyes
What are the progressive signs of measles?
fever and cough appear and rapidly intensify,
followed by a characteristic rash.
How long are measle symptoms?
7-10 days
What does the measles virus generate?
a strong immune response
How does the body eliminate measles?
Serum antibodies, along with cytotoxic T lymphocytes, combine to
eliminate the virus from the host.
What are measles postinfection complications?
Middle ear infection
Pneumonia
Measles encephalomyelitis (rare)
What is required to confer herd immunity to measles?
Vaccination of nearly 95% of the population?
What is the vaccine for measles?
Active immunity to measles is conferred with an attenuated virus
preparation as part of the MMR (measles, mumps, rubella) vaccine.
What are other names for rubella?
German measles or 3 day measles
Congenital rubella syndrome?
during the first three months of
pregnancy, rubella virus can infect the fetus by placental transmission
and cause serious fetal abnormalities including stillbirth, deafness,
heart and eye defects, and brain damage
What are symptoms of rubella?
- Symptoms of rubella resemble those of measles but are often restricted
to just the upper torso. - Rubella is less contagious than measles
Mumps are
- Inflammation of the salivary glands, typically the parotid gland (the
largest of the salivary glands)
The mumps virus spreads through the bloodstream, and may infect other organs:
- The testes
- Pancreas
- Encephalitis in rare cases
What is chicken pox and shingles called?
Varicella zoster virus (VZV)
VZV is a mild but highly contagious disease and is transmitted by
infectious droplets
* direct contact with chicken pox blisters of other children
* contaminated fomites
How does VZV work in the body?
enters the respiratory tract, multiplies, and is quickly
disseminated via the bloodstream, resulting in a systemic papular rash.
How many cases of chicken pox in 2011?
was about
15,000 cases, which is about 10% of those reported in 1995,
the year the vaccine was first licensed.
How many chicken pox related deaths?
Deaths from chicken pox are extremely rare, with six deaths
reported in 2011.
Direct nonsexual contact?
direct contact with an infected person
direct contact with blood or excretions from an infected person
fomites or animals to people
Staphylococci are?
nonsporulating, gram-positive cocci
divide in multiple planes to form irregular clusters of cells
They are resistant to drying
What two species of staphylococcus are important in humans?
- Staphylococcus epidermidis, a non-pigmented species usually found
on the skin or mucous membranes - Staphylococcus aureus, a yellow-pigmented species
Staphylococci commonly infect
infect skin, and wounds and may cause
pneumonia
Most staphylococcal infections result from
Transfer from the normal microbiota
* From the transfer an infected, asymptomatic individual
* Toxemia following the ingestion of contaminated food
Staphylococcal diseases include:
- Acne
- Boils
- Pimples
- Impetigo
- Pneumonia
- Osteomyelitis
- Carditis
- Meningitis
- arthritis.
S. aureus toxic shock syndrome (TSS) characterized by:
- high fever
- Rash
- Vomiting
- Diarrhea
- in some cases, death
Methicillin-resistant strains of S. aureus (MRSA)
infections
- Over 80 000 cases reported (10x more infected)
- Many HAI’s
- delayed treatment = extensive tissue damage
TSS is seen?
both men and women and is typically triggered by
staphylococcal infections following surgery.
* The symptoms of TSS result from toxic shock syndrome toxin-1
* This very potent exotoxin is a superantigen that is released during cell
growth and recruits large numbers of T cells to the site of infection.
Historical treatment for MRSA?
Penicillin, cephalosporin
Recent treatment for MRSA?
Clindamycin and tetracycline drugs
MRSA Treatment
s virtually impossible because many
people are asymptomatic carriers of S. aureus, either on their skin or in their
upper respiratory tract.
- practicing good basic hygiene:
- avoiding contact with the personal items (including clothing and towels) of
others - keeping wounds covered
- for those in the healthcare profession, following the established practices of
clinical microbiology safety
What is H pylori?
A gram-negative
* Highly motile and spiral-shaped bacterium
* Associated with gastritis, ulcers, and gastric cancers
* Colonizes the non-acid-secreting mucosa of the stomach and the upper
intestinal tract
What are the numbers for people infected with H pylori?
It is estimated that half the world’s population is chronically infected with
H. pylori.
* Up to 80% of gastric ulcer patients have concomitant H. pylori infections
* up to 50% of asymptomatic adults in developing countries are
chronically infected.
* There is no known nonhuman reservoir of H. pylori
* Infection occurs at high incidence within families, suggesting person-to-
person transmission.
* H. pylori infections also occasionally occur in clusters, suggesting that
transmission from common sources such as food or water is also
possible.
Symptoms of H pylori
Belching
Stomach (epigastric) pain
H pylori diagnosis?
Definitive diagnosis:
* the isolation or observation of H. pylori from a gastric ulcer biopsy.
* A simple noninvasive diagnostic test:
* Enzyme urease: a small amount of 13C- or 14C- labeled urea (H2N-CO-
NH2) is ingested; if H. pylori is present, the bacterium will hydrolyze
the urea, forming labeled CO2 and ammonia.
* presence of labeled in the patient’s breath is highly suggestive of H.
pylori infection.
H pylori treatment
- The combination treatment, administered for 14 days, abolishes the H.
pylori infection and provides a true cure.
1. antibacterial compound metronidazole and
2. tetracycline or amoxicillin, and
3. a bismuth-containing antacid preparation - Like the link with gastric ulcers, the link between H. pylori infection and
certain forms of gastric cancers, in particular, gastric adenocarcinoma
(the most prevalent form of gastric cancer), is also strong.
Hepatitis
Inflammation of the liver caused by an infectious agent
Chronic or acute hepatitis can
form liver cancer or cirrhosis
Types of hepatitis
A B C D E
Most common
A B C
Hepatitis A and E
occasionally transmitted from person to
person but are more commonly transmitted enterically by contaminated
food or water.
Hepatitis B
Bloodborne hepatitis
Hepatitis B transmission
In blood or bodily fluids
What kind of virus is HBV
hepadnavirus, partially double stranded DNA virus
Chronic HBV leads to
Cirrhosis and liver cancer
HBV transmission is from
blood transfusions
* contact with infected blood in a hypodermic needle
* mother to child during childbirth
* exchange of body fluids during sex
Hepatitis D
defective virus that lacks genes encoding its own capsid.
What can hepatitis D not do?
cannot replicate and form an intact virion unless the cell is also
infected with HBV.
What does HDV rely on?
The HDV genome replicates independently but relies on HBV to produce
capsid proteins (which are the same as those used by HBV) to form
infectious virions.
* HDV infections are always coinfections with HBV, and therefore the HBV
vaccine also indirectly protects against HDV.
Hepatitis C
parenterally by sharing needles of syringes for drugs
What does HCV produce
Hepatocarcinoma
How many people get liver cancer with HCV?
3-5%
Symptoms Of acute hepatitis
fever
jaundice
liver enlargement
cirrhosis
Chronic hepatitis infections by HBV or HCV
asymptomatic or
* produce very mild symptoms
* cause serious liver disease, even in the absence of liver cancer.
Diagnosis for hepatitis
clinical symptoms
2. laboratory tests that assess liver function, especially key liver
enzymes.
* Cirrhosis is diagnosed by visual examination of biopsied liver tissue.
* To confirm a diagnosis
* Virus-specific molecular assays for positively identifying the type of
hepatitis virus, and determining a course of treatment.
* Enzyme immunoassays that target viral-specific proteins or antiviral
antibodies in a blood sample, such as
* immunoblots (Western blots)
* immunofluorescence (microscopic) methods
* Polymerase chain reaction (PCR)
Prevention of hepatitis
- Infection with HAV or HBV can be prevented with effective vaccines.
- No effective vaccines are available for the other hepatitis viruses.
- For those unvaccinated, the practice of universal precautions will
prevent infection. - a high level of vigilance and aseptic handling and containment
procedures to deal with patients, body fluids, and infected waste
materials
Treatment: - Most treatment for hepatitis is supportive, providing rest and time for
the immune system to attack the infection and allow liver damage to be
repaired.
when did ebola emerge
1976 in Zaire
when did ebola re emerge?
2019 in democratic rebuild of Congo with over 2000 deaths reported
ebola occurs through person to person by
direct contact
* through breaks in the skin or mucous membranes
* by body fluids (including semen)
* fomites (bedding, clothing, utensils) contaminated with the virus
* natural Ebola infection in humans probably originates from an
animal bite
* The ease of transmission:
* in a few documented instances of Ebola transmission to healthcare
workers with full-body personal protective equipment (PPE)
Reservoir of ebola
The natural reservoir of Ebola virus that
triggered the West African outbreak is
unknown.
* Among the suspected reservoirs of Ebola are
a variety of animals and possibly insects that
inhabit tropical forests.
* In addition to person-to-person transmission,
natural Ebola infection in humans probably
originates from an animal bite.
* Bats in which the virus has been
documented may be a disease reservoir.
how does the ebola virus move in the body?
- from the initial site of infection to lymph nodes, from which it travels
systemically to infect the liver and spleen. - Once the virus has entered the body, several different types of cells can
become infected.
Ebola symptoms
ymptoms appear one to two weeks postinfection;
* an abrupt fever
* general malaise (makes it) difficult to be distinguished from many
other tropical diseases, including malaria.
* Severe fever
* Fatigue
* Diarrhea
* Nausea
* vomiting and abdominal pain
* major loss of appetite.
* Bleeding through the skin and blood in vomit and feces can occur,
but such bleeding is not a common symptom.
* Ebola virus causes major problems in the liver, killing liver cells
* disrupting normal blood clotting events.
* host cells release various cytokines that cause widespread
inflammation and internal bleeding; these lead to multiple organ
failures, shock, and renal failure.
Mortality rate of ebola depends on
the initial state of health of those infected
* viral load (abundance of the virus in the blood)
* age; mortality was as high as 85% among infected people over
the age of 45.
* access to treatment
Ebola treatment
There is no drug treatment for Ebola
* Survival rates among those that receive supportive care to help alleviate
symptoms are significantly higher than in those that do not.
