Download Infectious Diseases

Analyze issues of public health, infectious
diseases, and bioterrorism.
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Pathogens-microorganisms that are capable of causing
disease
Infection-results when a pathogen invades and begins
growing within the host
Disease-results only if and when tissue function is
impaired (i.e. burns, skin lesions)
The body has defense mechanisms to prevent infection
In order to cause disease, pathogens must be able to enter,
adhere, invade, colonize, and inflict damage
Entrance to the host-mouth, eyes, genital openings,
wounds
Growth of pathogens or the production of toxins/enzymes
cause disease
Some normal flora prevent diseases
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Bacteria-Salmonella typhi, Staphylococcus aureus
Viruses-apart from the host cell, have no
metabolism and cannot reproduce
Fungi-form spores
Protozoa-acquired through contaminated food or
water, or bite of an arthropod (mosquito)
Helminths-simple, invertebrate animals, some
infectious parasites – symptoms: abd. pain and
diarrhea
Prions-Creutzfeldt-Jakob disease
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Epidemiology –study of the occurrence of disease
in populations
Disease reservoirs-where the infectious agent
survives (humans, rodents) Example = yersinia
pestis
Modes of transmission
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Nonspecific mechanisms are the body’s primary
defense against disease-anatomical barriers,
physiological deterrents and presence of normal
flora (skin, low pH and high salinity)
Specific mechanisms-immunity
Vaccination-produces immunity
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Safe water-US water is purified through settling, filtration, and
chlorination
Sewage treatment and disposal is mandated by US government
Food safety-US has many standards, inspection plans and
regulations dealing food preparation, handling, and distribution
Animal control programs-Domestic herds are inspected, rabid
animals are destroyed, rat control programs in place in urban
areas
Vaccination programs mandate that children be vaccinated prior
to
school
Pesticides to block vector-borne disease – those carried by
mosquitoes
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National Institutes of Health (NIH)-supports
health-related research
Centers for Disease Control (CDC)-investigates
disease outbreaks, publishes reports, sponsors
education/ research, reference labs
Food and Drug Administration (FDA)-monitors
safety of food, medicines and other products
World Health Organization (WHO)-provides
international surveillance and control of disease
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New research techniques-rapid identification
HIV protease inhibitors
Vaccine research
Identification of better preventative measures
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Penicillins/cephalosporins interfere with certain
layers of cell wall
Chloramphenicol, tetracyclines, erythromycinsmay be toxic when used in high doses or
prolonged periods of time
Rifampin-used for treatment of TB
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Drugs that effectively inhibit viral infections are
highly toxic to host cells because viruses use the
host’s metabolic enzymes in reproduction
Antiviral drugs target virus-specific enzymes
Acyclovir-used in treatment of genital herpes
Amantadine-used to prevent or moderate
influenza
AZT-inhibit replication of HIV genome
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Development of drugs used to treat fungal,
protozoan, and helminthic diseases are also highly
toxic to mammals
Azole derivatives inhibit sterol synthesis
Amphotericin B-disrupts cell membrane
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Antimicrobial resistance presents ongoing
problems in the fight against infectious diseases
Penicillin resistance noted as early as 1943
Mycobacterium tuberculosis-some strains
resistant to all drugs
Resistance to antibiotics-result of changes in
genetic information
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* Globally, infectious diseases remain the leading
cause of death, and they are the 3rd leading cause
of death in the US
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Have not occurred in humans before,
Have occurred previously but affected only small
numbers,
Or have occurred throughout human history, but
only recently recognized as disease due to
infectious agent
Examples and contributing factors
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Once were major health problems globally or in a
particular country, then declined dramatically, but
are again becoming health problems for a
significant proportion of the population.
Examples and contributing factors
Bacterial – Anthrax and
Plague
 Viral - Smallbox
 Toxins – Botulism and Ricin
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Terrorism is defined in the United States Code,
Title 18, section 2331(18 USC 2331) as “Violent acts
or acts dangerous to human life that…appear to
be intended:
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To intimidate or coerce a civilian population;
To influence the policy of a government by
intimidation or coercion; or
To affect the conduct of a government by
assassination or kidnapping.
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Biological weapons used in bioterrorism are living
microorganisms such as bacteria, viruses, fungi,
that can kill or incapacitate.
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Health care facilities may be the initial site of
recognition and response to bioterrorism activity.
Because of this, the names and telephone numbers
for internal and external departments or agencies
that need to be contacted should be kept by each
facility in its bioterrorism readiness plan.
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1. Internal reporting requirements (within a
facility):
◦ Infection control personnel
◦ Epidemiologist (local and state)
◦ Administration (health care facility and health
department)
◦ Office of public affairs in the health facility
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2. External contacts (outside of facility)
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Local health department
State Health Department
FBI
CDC
Local police
EMS
◦Bacterial- Anthrax and Plague
◦Viral- Small Pox
 Toxins- Botulism and Ricin
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Acute infectious disease caused by bacillus
anthracis.
Infections in humans:
Skin contact – cutaneous, ingestiongastrointestinal, inhalation-pumonary
Person-to-person transmission of inhalation
disease does not occur. *
*direct exposure to vesicle secretions of cutaneous
anthrax can result in a secondary infection.
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Pulmonary signs and symptoms:
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Flu-like symptoms that may briefly improve two to four
days after initial symptoms
Abrupt onset of respiratory failure
Hemodynamic collapse
Thoracic edema
Widened mediastinum on xray
Positive blood culture in 2-3 days of illness
Prognosis:
Good if treated early. Increased mortality rate if treated
after respiratory onset.
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Cutaneous signs and symptoms:
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Local skin involvement with direct contact
Commonly seen on head, forearms, or hands
Localized itching followed by popular lesion that
turns vescular within 2-6 days – develops into
depressed black eschar
Prognosis:
Good if treated with antibiotics.
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Gastrointestinal signs and symptoms:
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Abdominal pain, nausea, vomiting, fever
Bloody diarrhea, hematemesis
Positive culture after 2-3 days
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Prognosis:
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If progression to toxemia and sepsis, prognosis is
poor.
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Modes of transmission:
◦ Inhalation of spores
◦ Skin contact
◦ Ingestion of contaminated food
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Incubation period:
◦ Pulmonary: 2-60 days
◦ Cutaneous: 1-7 days
◦ Gastrointestinal: 1-7 days
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Transmission:
◦ Anthrax is not airborne person to person. Direct contact
with infectious skin lesions can transmit infection.
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Prevention:
◦ Vaccine available-limited quantities.
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Potent neurotoxin caused by an anaerobic
bacillus- colstridium botulinum.
Transmission:
◦ Contaminated food
◦ Inhalation
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Signs and symptoms:
Gastrointestinal symptoms
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Drooping eyelids
Weakened jaw clench
Difficulty swallowing or speaking
Blurred vision
Respiratory distress
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Incubation period:
◦ Neurological SxS for food borne botulism – 12-36 hours
after ingestion
◦ Neurological SxS for inhalation botulism – 24-72 hours
after exposure
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Prevention: Vaccine available
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Botulism cannot be transmitted person to person.
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Plague is an acute bacterial disease caused by
yersinia pestis.
Signs and Symptoms:
Fever
Cough
Chest pain
Hemoptysis
Watery sputum
Bronchopneumonia on xray
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Mode of Transmission:
◦ Plague normally transmitted from an infected flea
◦ Can be aerosol-probable use in bioterrorism
◦ Can be transmitted person to person
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Incubation period:
Flea bite – 2-8 days
◦ Aerosol – 1-3 days
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Prognosis: Good if treated with antibiotics early.
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Ricin is a potent protein toxin derived from
Castor beans. Castor beans are found easily all
over the world and the toxin is fairly easily
produced. For this reason ricin could be used as
a biological weapon with relative ease.
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Infections in Humans
◦ Aerosol
◦ Ingestion
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Signs and Symptoms:
18-24 hours
Weakness
◦ Fever
◦ Cough
◦ Pulmonary edema
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36-72 hours
◦ Severe respiratory distress
◦ Death from hypoxemia
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Incubation period:
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8-18 hours
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Prognosis:
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Poor-no vaccine available
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Ricin does not spread easily person to person.
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Smallpox is an acute viral illness caused by the
variola virus.
Mode of transmission: Airborne: droplets
Signs and symptoms:
◦ Flu like symptoms-fever, myalgia
◦ Skin lesions appear quickly progressing from macules to
papules to vesicles
◦ Rash scabs over in 1-2 weeks
◦ Rash occurs in all areas at once, not in crops
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Incubation period:
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From 7 to17 days, average is 12 days
Contagious when the rash is apparent and
remains infectious until scabs separate (approx. 3
weeks)
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Prognosis:
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Vaccine available and effective post-exposure
Passive immunization is also available in the form
of vaccina- immune-globulin (Vig)
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Smallpox has a high mortality rate.