epidemiology: transmitted via respiratory secretions (both directly and indirectly),
~120 Rhinovirus strains,
~30 Adenovirus strains, Respiratory
Syncytial Viruses (more about
RSV), and others (coronaviruses, Coxsackie viruses, echoviruses, reoviruses)
cause millions of colds each year in US ... especially in children; Severe
Acute Respiratory Syndrome (SARS) emerged in China in 2003; this disease is casued
by a novel coronavirus (SARS-CoV)
... WHO reported that 8,098 people
worldwide developed SARS during the 2003 outbreak, and 774 of them died; the most recent cases
of SARS were laboratory-acquired infections in China in April 2004
treatment: TLC - symptomatic
relief; antibiotics
not useful (treatment advice from a pharmacist or
from a student health center)
prevention: avoid
contact with respiratory secretions of infected persons
Streptococcal Pharyngitis (strep
throat)
epidemiology: Streptococcus
pyogenes (bacterium); occurs mostly in children and young adults; frequently
related to tonsillitis and its complications
pathogenesis:
bacteria produce pyrogenic toxin which causes pharyngitis (cell
damage, inflammation leads to sore throat, coughing); frequently cause of tonsillitis; complications include scarlet
fever, rheumatic
fever and toxic
shock syndrome
treatment:
penicillin (erythromycin if patient is allergic to penicillin); symptomatic
relief
prevention: avoid contact with respiratory secretions of infected persons
epidemiology: Streptococcus pneumoniae,Haemophilus influenzae (bacteria)
or various viruses; most often affects children aged 3 months to 3 years old, but may occur
at any age
pathogenesis:
microbes invade the middle ear via the eustacean tube, causing inflammation that results in
swelling and fluid accumulation which can result in pain, fever, discharge and damage to the
eardrum, causing impaired hearing (and sometimes affecting balance); complications include perforation
of the eardrum or necrosis of the middle ear, leading to conductive hearing loss
treatment: antibiotics in conjunction with corticosteroids
prevention: avoid contact with respiratory secretions of infected persons
Meningitis
epidemiology: Streptococcus
pneumoniae (affects children most); Haemophilus influenzae (this
bacterium mostly affects children 6 months to 2 years old); Neisseria
meningitidis (~2500 cases per year ... affects young adults most); Listeria
monocytogenes (actually infects via the gastrointestinal tract,
but ends up causing the same syndrome as the others) - all these microbes
are bacteria, but viruses and fungi can also cause meningitis; ~8000
cases of aseptic (viral) meningitis per year in the US
pathogenesis:
damage to meninges (headache, coma) - complications include disseminated
intravascular coagulopathy (DIC), kidney and skin damage, death (~250
per year in the US)
treatment:
ampicillin (Haemophilus); penicillin (Listeria,
Neisseria, and Streptococcus); amphotericin B (fungi); TLC, symptomatic
relief (viruses)
prevention:
vaccines
Hib
vaccine induces immunity against meningitis caused
by Haemophilus influenza b
Menomune induces
immunity against major strains of Neisserial meningitis
epidemiology: Rubeola
virus is transmitted via respiratory secretions before symptoms appear; ~100 cases of
measles reported in US each year
pathogenesis:
upper respiratory tract infection (10-14 days;
"cold-like" symptoms) leads to systemic infection which results in Koplik spots, then skin rash
with high fever, delirium; complications - blindness (vitamin A deficiency), pneumonia (4-7%),
encephalitis, seizures, death (~10%; kills ~1 million people (mostly children) per year worldwide);
not teratogenic, but intrauterine rubeola infection can cause stillbirth, premature delivery,
fatal congenital encephalitis; SSPE (subacute sclerosing panencephalitis)
epidemiology: Herpes
Varicella-Zoster Virus is transmitted via respiratory secretions; most contagious
human disease; ~50,000 cases per year in US (85% in 0-9 year-olds; 13% in 10-15 year-olds)
pathogenesis: upper respiratory tract infection ("cold"-like symptoms) leads to systemic
infection, which causes fever, vesicular
eruptions (lesions) of skin; complications - secondary bacterial infections (pneumonia,
encephalitis (coma)), death (20% of adults); Reye's syndrome; congenital
defects if infected during first
trimester of pregnancy; shingles or
zoster, which results from stress-induced activation of latent virus, leading to painful lesions
on the skin or eye ...
700,000-900,000 cases of shingles every year in the US; mostly in the over-50 crowd, peak
incidence at 60-79 years of age
treatment: TLC, symptomatic relief (for chickenpox - acetaminophen calamine lotion,
acyclovir (zovirax), famvir or valtrex;
for encephalitis, vidarabine (Vira-A) or famvir for
shingles, Zostrix (OTC analgesic)
prevention: Varicella vaccine (more
vaccine info); avoid contact with respiratory secretions of infected persons;
varicella-zoster immune globulin (VZIG)
epidemiology: Variola Virus - transmitted via respiratory secretions, vesicular
fluid, or lesion crusts from infected persons; 0 cases per year in the whole world ...
this disease is thought to have been eradicated in the 1970s (last "wild" case in Somalia in
1977)
pathogenesis: upper respiratory tract infection leads to systemic infection (fever,
chills, headache, backache) which leads to vesicular
eruptions (lesions) of skin; complications - disfiguration due to massive
scar formation; death in severe cases (up to 90%) ... bioterrorism
information
the US stopped routine universal vaccination
against smallpox in the 1970s because there is a bigger
chance of harming those who are immunodeficient than
there is of saving others (since the disease was
eradicated worldwide during that decade)
smallpox vaccine is, however, made available to
healthcare workers in the US
perhaps as few as 20% of those vaccinated a generation
ago are still immune
countries other than the US still vaccinate (or at least
did so as recently as 20 years ago)
avoid contact with respiratory secretions, vesicular fluid, or lesion crusts from
infected persons
epidemiology: Epstein-Barr
Virus (EBV) and Cytomegalovirus (CMV)
are transmitted by close oral contact (kissing); prevalent among teens
in US; ~90% of adults in the US have antibodies against EBV
pathogenesis: First, sore throat (pharyngitis) with swollen
glands (cervical lymphadenitis) and fever develops; then mononucleosis
(monocytosis), muscle aches and fatigue develop; acute illness usually
lasts 7-14 days, but it is important not to overexert for up to 6 weeks;
complications include hepatitis, meningitis, myocarditis, paralysis,
ruptured spleen, facial paralysis, chronic fatigue syndrome ("yuppie
flu"), and death (rare)
treatment: TLC (much bed rest, little strenuous exercise, no
alcohol)
prevention: avoid contact with respiratory secretions of infected
persons
epidemiology: Corynebacterium
diphtheriae (bacterium) - few cases in US due to vaccine-induced "herd" immunity
(fewer than 10 cases per year in the US); countries of the former
Soviet Union have reported >150,000 cases in an epidemic the began
in 1990; the Iditarod,
a ten-day dog-sled race commemorates a desperate race against time
to transport diphtheria antitoxin from Anchorage to Nome, Alaska,
during the 1925 epidemic; Elisha Otis, the inventor of the elevator,
died of diphtheria
pathogenesis:
pharyngitis (cell damage, inflammation leads to sore throat, coughing);
diphtheria toxin causes pseudomembrane formation in the throat, then
toxin goes systemic to cause heart, kidney and CNS damage (inhibits
cellular protein synthesis); complications include paralysis, death
treatment: antitoxin, then penicillin
prevention: DTaP
vaccine @ 2, 4, 6, 18 months and Td vaccine boosters at 7-10 year
intervals); avoid contact with respiratory secretions
epidemiology: Bordetella
pertussis (bacterium) - human reservoir ... inhalation of respiratory droplets
containing the bacteria; ~15,000 cases in US per year (~250,000 cases in 1950; lower
now because of vaccine use)
pathogenesis:
1-3 week incubation period leads to pharyngitis (cell damage, inflammation due to pertussis
toxin causes sore throat, coughing), then progresses to bronchitis (loss of ciliated
epithelial cells) causing bronchial accumulation of mucus and repetitive coughing;
complications - 0.5-10% death rate
pathogenesis:
after 1-4 days (average of 2 days), nasal epithelial infection leads to abrupt onset of rhinitis
(inflammation causes nasal secretions, sneezing), then pharyngitis (inflammation causes sore
throat, coughing), then bronchitis (due
to ciliated epithelial cell loss) which leads to malaise, chills, fever, headache, nonproductive
cough, muscle aches, joint soreness, weariness; the disease itself usually lasts for several
(5-7) days, but the cough and malaise can last for 2 or more weeks (how
to distinguish between colds and flu); complications include primary influenza viral pneumonia
or secondary bacterial pneumonia ... together, influenza and pneumonia together constitute
the number 8 killer in the US ...56,247 people died of this combination in 2006;
Guillain-Barre syndrome; Reye's Syndrome (aspirin induces Reye's Syndrome in children?)
treatment:
TLC - symptomatic relief (but don't treat children with aspirin); amantadine prevents influenza
A; neuraminidase
inhibitors (Relenza, Tamiflu) shorten length of illness by one day (if taken at onset of
signs and symptoms)
prevention: influenza
vaccine (who
should get it? ... elderly, diabetics, anemics; cardiac, pulmonary, renal patients) avoid
contact with respiratory secretions of infected people
~5 million cases reported each year in the US; 56,247 people died of pneumonia
(together with influenza)in 2006 ... making this combination the number 8 killer
in the US
Streptococcus
pneumoniae (this bacterium generally causes secondary infections); other bacteria,
including Legionalla pneumophila, which causes Legionaires' Disease, and Mycoplasma
pneumoniae or Chlamydia pneumoniae which both cause primary atypical or "walking" pneumonia; Pneumocystis
jirovecii {formerly Pneumocystis carinii} an opportunistic fungus that infects
mostly immunocompromised individuals; Respiratory Syncytial Virus (causes
disease mostly in children under the age of two)
pathogenesis: infection
of alveoli leads to accumulation of fluid in lungs, which causes congestion (difficulty breathing,
loss of energy, fever); complications include congestive heart failure, meningitis, death
treatment:
CTAs for bacteria ... penicillin for S. pneumoniae; tetracycline or erythromycin
for M. pneumoniae, C. pneumoniae, or L. pneumophila
CTAs for P. carinii ... pentamidine, sulfa drugs (SxT)
TLC, including symptomatic relief, for viruses such as RSV
epidemiology: Legionella pneumophila (first
detected in Philadelphia, at an American Legion convention in
1976, when it was linked to inhalation of water droplets from
water-cooled air conditioning systems); ~1000-1300 cases are
reported each year, but there may be as many as 25,000 actual
cases per year, in the US
pathogenesis: pneumonia, with malaise, myalgia,
headache, cough and moderate fever; complications include
death
treatment: erythromycin
prevention: disinfection of water-based evaporative
air conditioning systems
epidemiology:
Hantavirus is transmitted via inhalation of aerosolized
deer mouse urine, feces or saliva; prevalent in Southeast Asia,
where it causes ~100,000 cases each year; new strains emerged
in southwestern
US (four corners area) in 1993; since then, there have been
more than 180 cases of HPS in the US ... with ~50%
mortality
pathogenesis:
respiratory infection leads to development of nonspecific signs and symptoms that can include fever,
muscle aches, headache, abdominal pain, nausea, and vomiting, followed later by coughing and
shortness of breath (respiratory distress) due to edema and interstitial pneumonitis in the lungs
as a result of excessive immune response, typified by the presence of immunoblasts in the blood;
signs and symptoms usually occur between 1 and 6 weeks after exposure to virus-laden rodent excreta complications - rapidly progresses (within 5-6 days) to acute respiratory
distress syndrome (ARDS) which requires the patient to receive intensive care; can
lead to cardiac and respiratory failure ... sudden death due to fluid accumulation in the
lungs (10-70%
death rate)
treatment: TLC ... symptomatic relief; provide ventilation
(oxygenation when needed) and minimize fluid accumulation in lungs
prevention:
avoid
contact with deer mouse urine, feces or saliva ... mouse control
epidemiology: Mycobacterium
tuberculosis (bacterium) - 13,299 cases (and ~1300 deaths) in 2007 in the US; during
the 1940s, ~100,000 cases each year (and ~40,000 deaths); there are now ~2 billion infected
people worldwide, with ~8 million
new cases and ~3 million deaths each year in the world ... TB is the leading cause of death
from a single identifiable infectious disease in the world as a whole, and the main cause
of preventable death people ages 15-40; etiology of TB was established by Robert Koch
in the late 1800s
pathogenesis: survives
inside macrophages; chronic
lung infection leads to granuloma formation, causes poor lung function (cough, bloody
sputum, pain, lack of energy, weight loss, night sweats); complications include chronic
progressive lung disease, death (50% mortality without treatment)
epidemiology: Histoplasma
capsulatum (fungus) - inhalation of spores present in bird droppings transmits; ~500,000
new cases per year in US; highest incidence in people between 15-34 years old; H. capsulatum infections
clustered geographically (primarily SE US)
pathogenesis:
lung infection (5-18 days) leads to granuloma formation and causes loss of lung function (lack
of energy) together with fever, chills, cough that brings up mucus or pus, and possible joint
stiffness; very similar to TB, but less serious; complications - chronic, progressive lung
disease, spread via blood to other organs (more likely in immunosuppressed people or in very
young children); death ... mortality rate of 0.05 per 100,000 (138 deaths per year)
treatment: amphotericin B, ketoconazole or itraconazole
prevention: avoid contact with bird droppings (which contain spores)
