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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, erythromycins- may 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 3 rd 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
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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: 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) ◦ Local health department ◦ State Health Department ◦ FBI ◦ CDC ◦ Local police ◦ EMS
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◦ 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, 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.
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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.
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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.
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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.
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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
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Transmission: ◦ Anthrax is not airborne person to person. Direct contact with infectious skin lesions can transmit infection. Prevention: ◦ Vaccine available-limited quantities.
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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
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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 Prevention: Vaccine available 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 Incubation period: Flea bite – 2-8 days ◦ Aerosol – 1-3 days 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. Infections in Humans ◦ Aerosol ◦ Ingestion
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Signs and Symptoms: 18-24 hours Weakness ◦ Fever ◦ Cough ◦ Pulmonary edema 36-72 hours ◦ Severe respiratory distress ◦ Death from hypoxemia
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Incubation period: 8-18 hours Prognosis: Poor-no vaccine available 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: 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: 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.
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