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Chapter 22 Lecture 5 Bacterial Diseases of the Lower Respiratory System
Chapter 22 Lecture 5
Bacterial Diseases of the Lower Respiratory System
Inhalational Anthrax
Biological terror agent
Three forms of anthrax: cutaneous anthrax, gastrointestinal anthrax, and inhalational anthrax
Signs and symptoms
Initially resembles a cold or flu- sore throat, mild fever, myalgia, mild cough, and malaise.
Progresses to severe coughing, lethargy, shock, confusion, fainting and death
Pathogen and virulence factors
Bacillus anthracis is the causative agent inhale at least 8000-50,000 endospores
Virulence factors include a capsule and anthrax toxin which impairs respiratory function, initiates toxemia and will result in death
Pathogenesis and epidemiology
Anthrax does not spread from person to person
Acquired by contact or inhalation of endospores
Diagnosis, treatment, and prevention
Diagnosis based on identification of bacteria in sputum
Early and aggressive antimicrobial treatment is necessary
PCN is the preferred drug but often anthrax is so severe that rapid treatment is ineffectual.
When accompanied by drainage of fluid from around the lung survival rate increased from 1% to 50%
Anthrax vaccine is available to select individuals such as military. Researchers, and healthcare professionals with anthrax patients
Influenza
Flu pandemic in the winter of 1918-1919
Half the world's population was infected with a new extremely virulent strain of influenza and 40 million people died
Common respiratory disease second in prevalence only to common colds, but yet can be very devastating.
Signs and symptoms
Sudden fever, (102-106 ̊F)
Pharyngitis, congestion, cough, and myalgia
Sudden fever distinguishes the flu from a common cold
Most people will recover in 1-2 weeks
Pathogens and virulence factors
Influenza virus types A and B are the causative agents and they enter the body via the respiratory route. The virus will attach to epithelial cells and replicates. It replicates in upper and lower system. Once inside the cell, it releases the viral genome into the cytoplasm
Mutations in the hemagglutinin and neuraminidase produce new strains
Occurs via antigenic drift and antigenic shift
Concern about the fatality associated with strains similar to those of past pandemics
Pathogenesis
Virus causes damage to the lung epithelium
Flu patients are susceptible to secondary bacterial infections
Epidemiology
Infection provides some immunological protection from similar strains
Concern that changes in type A influenza viruses may cause another major pandemic
Diagnosis, treatment, and prevention
Signs and symptoms during a community-wide outbreak are often diagnostic
Lab tests such as ELISA , immunofluorescence and rapid antigen testing can distinguish strains of the flu virus
Treatment involves supportive care to relieve symptoms
Oseltamivir and zanamivir can be administered early in infection needs to be administered within 48 hours of infection
Prevented by immunization with a multivalent vaccine
70% effective
Good hand hygiene
Coronavirus Respiratory Syndromes
Two recently emerging diseases
Severe acute respiratory syndrome (SARS) 2003 the people of China were wearing masks to prevent the spread of coronavirus
Middle East respiratory syndrome (MERS)- Changing the face of the Middle East and South Korea
Signs and symptoms
High fever, shortness of breath, difficulty breathing, malaise, and body aches. 10-20% of pts will have diarrhea
Later, patients develop a dry cough and pneumonia
10% of SARS pts dies
55% of MERS will die
Pathogen and virulence factors
Coronaviruses are the causative agent
Most diseases are usually mild
2nd most common cause of the cold
SARS and MERS have higher fatalities and pandemics are alarming
Pathogenesis and epidemiology
Coronaviruses spread via respiratory droplets and they adhere to lung cells. Virus destroys the cells , triggering the respiratory symptoms
Virus spreads from the lungs to the heart and kidneys
Diagnosis, treatment, and prevention
Diagnosis is based on signs and symptoms
Confirmed by isolating the virus or antibodies against the virus
Tract the disease in only 6 months. WHO reported 8098 were infected and 774 died.
Had it under control within one year.
Treatment is supportive
MERS- not contained as quickly. First became aware in 2013 in Saudi Arabia.Camels are the main host for the MERS virus
Respiratory Syncytial Virus (RSV) Infection
Most common childhood respiratory disease in newborns and young children
Signs and symptoms (after 4-6 days)
Fever, runny nose, and coughing in babies or immunocompromised individuals, cyanosis, sometimes wheezing . Plugs of mucus, fibrin and dead cells make it hard to breath
Mild cold like symptoms in older children and adults
Leading cause of bronchiolitis and pneumonia among children Less than 1 year and leading cause of death in infants worldwide
Pathogen
Respiratory syncytial virus, unstable outside the body surviving only 5 hours in the environment or 2 hours on skin or used facial tissue
Soap and water deactivate RSV
Pathogenesis
Virus causes syncytia to form in the lungs
A syncytium is a giant, multinucleated cell formed from the fusion of virally infected cells to neighboring cells.
Immune response to RSV further damages the lungs
Diagnosis, Treatment, and Prevention
Spreads by kissing touching and shaking hands or coming into contact with fomites
Immunocompromised patients and babies, exposed to tobacco smoke, attend day care, or have older school aged siblings are at risk
Kills 14, 000 elderly pts annually , 2000 babies per year will die.
Prompt diagnosis based on S/S but verification of RSV is made by immunoassay.
Supportive treatment includes, administering oxygen, IV fluids and medication to reduce fever, and AB to reduce secondary bacterial infection
Control of RSV is limited to attempts to delay infection.
Handwashing
Hantavirus Pulmonary Syndrome (HPS)
Signs and symptoms
Symptoms fever, fatigue and muscle aches (especially large muscles of the thigh, hips, and back) progress to cough, shock, and labored breathing, Pathogen
Caused by Hantavirus
Transmitted from mice via inhalation mouse urine, feces, or saliva
Pathogenesis
Hantavirus travels throughout the body via the blood
Infection causes widespread inflammation leading to shock
Epidemiology
Human disease more likely as mouse population increases
Person-to-person contact does not occur
Diagnosis, treatment, and prevention
Diagnosis is based on characteristic symptoms low platelet count, sudden onset fever, muscle aches in major large muscles
No pharmacological treatment is available
Vent, antipyretics, pain med,
Prevention requires control of rodents