micro chapter 3 diseases

what pathogen is best identified by negative stain

Lyme disease (Borrelia burgdorferi)

what pathogen is best identified by acid-fast staining

Tuberculosis (Mycobacterium tuberculosis)

what are some pathogens that are endospore-forming microbes

tetanus, Botulism, Anthrax

what is the etiology of Lyme disease

• Borrelia burgdorferi

• relatively large spirochete

• evades the immune system by changing surface proteins (antigens)

• has multiple proteins for attachment to host cells

what is the epidemiology of lyme disease

• first discovered in Old Lyme, Connecticut in the 1970s

• more then 20,000 confirmed from 2006-2013

• most cases reported during june and july

  • spirochete is transmitted to human host by tick bite

what are the signs and symptoms of lyme disease

• slow, progressive syndrome

• 70% of cases develop a bull’s eye rash

• fever, stiff neck, and dizziness

• swollen lymph nodes may occur

• heart palpitation due to changes in heartbeat

• develops into crippling arthritis after several weeks to months

what is the treatment for lyme disease

• earlier treatment with antibiotics leads to better recovery

  • doxycycline, amoxicillin, or cefuroxime axetil

  • Patients with other neurologic conditions do better with intravenous ceftriaxone or penicillin

what are the long-term issues for lyme disease

• Post-treatment Lyme Disease Syndrome can last for 6+ months following antibiotics

  • Occurs in 10 – 20% of patients despite treatment

  • Include fatigue, pain, or joint and muscle aches

• Cause may be damage to tissues and immune system following infection

  • Not helped using long-term courses of antibiotics

  • Time does appear to alleviate the symptoms

what are the preventative measure for lyme disease

• Vaccination was discontinued in 2002 due to low demand

  • Those previously vaccinated are no longer protected as protecting is NOT long-lasting

what is tuberculosis

• An ancient human disease:

  • Found in mummies from the Stone Age, Ancient Egypt, and Peru

  • Prevalent cause of disease historically – “Captain of the Men of Death,” “The White Plague”

  • Streptomycin reduced rates significantly

• Now a reemerging disease

  • HIV epidemic

  • Drug-resistant strains

  • Nearly 1/3 of the world’s population is infected

what is the etiology of tuberculosis

• Mycobacterium tuberculosis

• Long, thin acid-fast rod (red)(red)

  • Mycolic acid and waxes

  • Makes the organism resistant to
    drying and disinfectants

what is the difference between primary and secondary tuberculosis

• The presentation of secondary tuberculosis is different from that of primary progressive disease as the hypersensitivity, and tissue reaction is more severe in secondary tuberculosis.

• Primary tuberculosis often causes middle and lower lung field opacities associated with mediastinal adenopathy.

what is the epidemiology of tuberculosis

• Transmission through fine droplets of respiratory mucus suspended in the air

• Epidemiological patterns vary with the living conditions of a community or area of the world

• TB is often an infection of poverty

what are the signs and symptoms of tuberculosis

• Once in lungs:

  • Cough lasting 3 or more weeks

  • Pain in the chest

  • Bloody and/or greenish sputum

• Fatigue, loss of appetite and weight, chills, fever, and night sweats also occur

• Patients with a latent infection are asymptomatic

  • Cannot spread infection easily to others

what are the risk factors for tuberculosis

• Persons who have been recently infected with TB bacteria are at risk including:

  • Close contact to someone with infectious TB, those from areas with high rates of TB, the poor, and intravenous drug users

  • Clinicians working in hospitals, homeless shelters, correctional facilities, and nursing homes

• Persons with medical conditions that weaken the immune system are at risk

  • HIV, diabetes mellitus, patients with organ transplants, and certain cancers

what helps determines the diagnoses for tuberculosis

• Mantoux tuberculin test

  • Shows evidence of delayed hypersensitivity after initial infection with TB

  • Purified protein derivative is injected under the ski

• IGRA

  • Blood test to determine T-cell reactivity to M. tuberculosis

  • Chest X-rays verify TB when other tests give indeterminate results

what is the treatment for tuberculosis

• If dealing with active tuberculosis:

  • First two months: Rifampin, isoniazid, ethambutol

  • 4 – 7 months: rifampin, isoniazid

• For latent tuberculosis:

  • Isoniazid, rifampin, rifapentine

• Patient noncompliance leads to drug-resistant strains

  • MDR-TB

how to prevent tuberculosis

• Methods in healthcare must include:

  • Prompt detection of infectious patients

  • Airborne precautions to reduce TB in air

  • Treatment of people who have suspected or confirmed TB disease

• Avoid long-term exposure to people in or from crowded, enclosed facilities

  • Clinics, hospitals, prisons, or homeless shelters

what is the etiology of anthrax

• Bacillus anthracis

  • Found naturally in soil and commonly affects domestic and wild animals

  • Produces several toxins that cause the symptoms of anthrax

    • Edema toxin leads to inflammatory conditions

    • Lethal toxin causes death of host cells

• Gram-positive, endospore-forming rod

  • Endospores are produced under adverse environmental
    conditions

what are the types of anthrax

• Cutaneous: spores get into the skin, usually through a cut or scrape

  • 20% mortality if untreated

• Gastrointestinal: consumption of spores from raw or undercooked meat from an animal infected with anthrax

  • 60% mortality if untreated

• Respiratory: inhaling anthrax spores

  • 90% mortality if untreated, 45% if treated aggressively

what is the epidemiology of anthrax

• Infection occurs through contact with bacterial spores

• Cutaneous and respiratory anthrax most common among people who work with livestock

• Gastrointestinal anthrax is rare in US

  • Result of annual vaccination of livestock

• Reports of injection-related anthrax is being reported among heroine users in Europe

what are the symptoms of anthrax

• Cutaneous anthrax may result in a black eschar when endospores enter the skin and germinate there

• Gastrointestinal anthrax can lead to fever and chills, swelling of glands in neck, sore throat, hoarseness, nausea and vomiting, headache, and stomach pain and/or swelling

• Respiratory anthrax can lead to fever and chills, chest discomfort, shortness of breath, dizziness, coughing, nausea and vomiting, headache, sweats, fatigue, and body aches

what helps determine the diagnoses for anthrax

• Chest x-rays may help with diagnosis of respiratory anthrax

  • Detects mediastinal widening or pleural effusion

• Best methods include:

  • Direct testing for Bacillus anthracis in samples

  • Measurement of antibodies or toxin in blood

what are the risk factors of anthrax

• Veterinarians, laboratory professionals, livestock producers and people who handle animals, and mail handlers, military personnel, and response workers who may be exposed during a bioterrorism event

  • Interestingly, also people who play animal hide drums have been known to become sick

• Travelers to Central and South America, Sub-Saharan Africa, Central and southwestern Asia, Southern and eastern Europe, and the Caribbean

what are the treatments for anthrax

• Early treatment with antibiotics is key

  • Intravenous antibiotics may be recommended

  • Ciprofloxacin and doxycycline are commonly used

• Antitoxins can also be effective in eliminating the toxin that causes the effects of anthrax

  • Also requires concurrent administration of antibiotics to
    eliminate the bacterial source of the toxin

how to prevent anthrax

• Anthrax Vaccine Adsorbed (AVA) protects against cutaneous and inhalation anthrax

  • Does NOT contain any bacteria

  • Consists of 5 shots over 18 months, along with annual boosters

  • If given POST-exposure, then 3 shots are recommended along with a 60-day course of antibiotics

  • Recommended for laboratory workers working with anthrax, veterinarians and others who work with animals, and US military personnel in high-risk areas

is anthrax a bioterror

yes and

• Listed by US as a Tier 1 bioterror agent

• Spores can be easily distributed in powders, sprays, food, and water

  • 22 cases of anthrax being sent through the mail occurred following bioterrorist attacks in the fall of 2001; 5 died as a result of exposure

• A small dose can be deadly and is easily aerosolized

what is the etiology of botulism

• Clostridium botulinum

  • Gram-positive, endospore-forming rod

  • Endospores are only produced under anaerobic conditions

  • Can be found in soil

what are the symptoms and complications of botulism

• Botulinum toxin travels to the neuromuscular junctions of skeletal muscles

  • Prevents the release of acetylcholine

  • Results in flaccid paralysis

  • Death due to respiratory failure

• Utilized by doctors to treat uncontrolled muscle spasms, migraine headaches, and other conditions

• Also used cosmetically to relax wrinkles in skin of face

is botulism foodeborne

yes and

• Caused by an intoxication which is rarely associated with an actual infection

  • Seven toxins have been identified

  • Only types A, B, E and F cause illness in humans

• Associated with eating poorly preserved foods

  • 10 – 30 outbreaks per year in the US

  • Many occur in Alaska from eating raw or undercooked fish

name things botulism can infect

• wound botulism:

  • Both an infection and an intoxication disease

    • Results from a wound infected with Clostridium botulinum

    • Symptoms are caused by the toxin

• intestinal botulism:

  • Both an infection and an intoxication disease

  • Infants become infected by ingesting spores

    • Spores germinate in the intestinal tract of infant leading to toxin production

  • Adults can also experience this disease

    • Far more rare because of the normal microbiota

what helps the diagnoses for botulism

• Patient history and physical examination may initiate the detection

  • However, other neurologic diseases can have similar symptoms (e.g. Guillain-Barré syndrome, stroke, and myasthenia gravis)

• Specific tests for botulinum toxin and for bacteria that cause botulism can be performed at some state health department laboratories and at CDC

what are the treatments for botulism

• Early detection is key

  • Foodborne botulism can be treated with an antitoxin

  • Wound and intestinal botulism can be treated with both antibiotics and antitoxin

• Respiratory failure and paralysis that occur with severe botulism may require a patient to be on a breathing machine

how to prevent botulism

• Foodborne botulism is best prevented by properly heating foods to appropriate temperatures for at least 10 minutes

  • Botulinum toxin is a protein

  • Canned foods are often a source of the intoxication

• Wound and intestinal botulism is harder to avoid since the bacteria is common in soil

  • Children under age of 1 should also avoid honey as it can contain the spores

what is the etiology of tetanus

• Clostridium tetani

  • Gram-positive, endospore-forming rod

  • Endospores are only
    produced under anaerobic
    conditions

what it the epidemiology of tetanus

• Common resident of soil and GI tracts of animals

• Bacteria or spores enter through wounds in the skin including:

  • Contaminated with dirt, feces, or saliva

  • Caused by an object puncturing the skin, like a nail or needle

  • Burns or injuries with dead tissue

• Incubation period is 3 – 21 days (10 average)

  • Most symptoms appear within 14 days of exposure

what are the symptoms and diagnoses for tetanus

• Clinicians must detect the symptoms of the disease including:

  • Headache

  • Jaw cramping

  • Involuntary muscle tightening (often stomach)

  • Painful muscle stiffness

  • Trouble swallowing

  • Seizures

  • Fever and sweating

  • High blood pressure and fast heart rate

what are the complications of tetanus

• Tetanospasmin binds to target sites on peripheral motor neurons on the spinal cord, brain, and nervous system

  • Blocks inhibition of muscle contraction, causing muscles to contract uncontrollably

  • Results in spastic (rigid) paralysis

• Death results from paralysis of respiratory muscles

  • Occurs in 10 – 20% of cases

what are the treatment for tetanus

• Hospitalization

• Treatment with human tetanus immune globulin (TIG)

• Tetanus vaccination

• Drugs to control muscle spasms

• Aggressive wound care (debridement)

• Antibiotics

what is etiology

Etiology is the study of disease causes, including genetics, environment, behavior, and physiology.

what is epidemiology

the branch of medicine which deals with the incidence, distribution, and possible control of diseases and other factors relating to health.