Analyze issues of public health, infectious diseases, and bioterrorism.

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

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

Epidemiology –study of the occurrence of disease in populations

Disease reservoirs-where the infectious agent survives (humans, rodents) Example = yersinia pestis

Modes of transmission

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

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

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

New research techniques-rapid identification

HIV protease inhibitors Vaccine research Identification of better preventative

measures

Penicillins/cephalosporins interfere with certain layers of cell wall

Chloramphenicol, tetracyclines, erythromycins-may be toxic when used in high doses or prolonged periods of time

Rifampin-used for treatment of TB

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

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

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

* Globally, infectious diseases remain the leading cause of death, and they are the 3rd leading cause of death in the US

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

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 - SmallboxToxins – Botulism and Ricin

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:

  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.

Biological weapons used in bioterrorism are living microorganisms such as bacteria, viruses, fungi, that can kill or incapacitate.

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.

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

2. External contacts (outside of facility)◦ Local health department◦ State Health Department◦ FBI◦ CDC◦ Local police◦ EMS

◦Bacterial- Anthrax and Plague

◦Viral- Small Pox Toxins- Botulism and Ricin

Acute infectious disease caused by bacillus anthracis. 

Infections in humans:   Skin contact – cutaneous, ingestion-

gastrointestinal, 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.

Pulmonary signs and symptoms:   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.

Cutaneous signs and symptoms:   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.

Gastrointestinal signs and symptoms:   Abdominal pain, nausea, vomiting, fever Bloody diarrhea, hematemesis Positive culture after 2-3 days   Prognosis:   If progression to toxemia and sepsis,

prognosis is poor.

Modes of transmission: ◦ Inhalation of spores◦ Skin contact◦ Ingestion of contaminated food 

Incubation period: ◦ Pulmonary: 2-60 days◦ Cutaneous: 1-7 days◦ Gastrointestinal: 1-7 days 

Transmission: ◦ Anthrax is not airborne person to person. Direct

contact with infectious skin lesions can transmit infection.

  Prevention: 

◦ Vaccine available-limited quantities.

Potent neurotoxin caused by an anaerobic bacillus- colstridium botulinum.

Transmission:◦ Contaminated food◦ Inhalation

Signs and symptoms:   Gastrointestinal symptoms

◦ Drooping eyelids◦ Weakened jaw clench◦ Difficulty swallowing or speaking◦ Blurred vision◦ Respiratory distress

Incubation period: ◦ Neurological SxS for food borne botulism – 12-36

hours after ingestion◦ Neurological SxS for inhalation botulism – 24-72

hours after exposure 

Prevention: Vaccine available   Botulism cannot be transmitted person to

person.

Plague is an acute bacterial disease caused by yersinia pestis. 

Signs and Symptoms:  Fever Cough Chest pain Hemoptysis Watery sputum Bronchopneumonia on xray

Mode of Transmission: ◦ Plague normally transmitted from an infected flea◦ Can be aerosol-probable use in bioterrorism◦ Can be transmitted person to person

Incubation period:   Flea bite – 2-8 days

◦ Aerosol – 1-3 days Prognosis: Good if treated with antibiotics

early.

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.

Infections in Humans◦ Aerosol◦ Ingestion

Signs and Symptoms:  18-24 hours Weakness

◦ Fever◦ Cough◦ Pulmonary edema

36-72 hours◦ Severe respiratory distress◦ Death from hypoxemia

Incubation period:   8-18 hours   Prognosis:   Poor-no vaccine available   Ricin does not spread easily person to

person.

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

Incubation period:   From 7 to17 days, average is 12 days Contagious when the rash is apparent and

remains infectious until scabs separate (approx. 3 weeks)

 

Prognosis:   Vaccine available and effective post-

exposure Passive immunization is also available in the

form of vaccina- immune-globulin (Vig)   Smallpox has a high mortality rate.