infectious disease 2 Flashcards
Tuberculosis
An infectious, inflammatory systemic disease that affects that lungs and may disseminate to involve lymph nodes and other organs
Caused by Mycobacterium tuberculosis
Infection most commonly occurs through inhaled droplets
Mycobacterial infections
Mycobacteria are small, slow-growing aerobic bacteria distinguished by a complex, lipid-rich cell envelope
Diseases caused by mycobacteria include tuberculosis and leprosy
Tuberculosis pathogenesis
Once a susceptible person inhales an infected droplet, the bacteria become established in the lungs and a proliferation of epithelial cells surrounds and encapsulates the multiplying organisms in an attempt to wall them off
The granulomas eventually become necrotic in the center leading to fibrosis and calcification of tissues. In later stages of the disease, the bacteria is able to enter the blood and lymph circulation and ultimately colonize distant sites.
TB kills 3 million people per year (worldwide)
Leading infectious disease cause of death
Represents 1/3 of world’s preventable deaths
TB S&S
Fever night-time seating Loss of weight Persistent cough Constant tiredness loss of appetite
TB DX and TX
Diagnosis - culture sputum; tuberculim skin test
Treatment - antibiotic cocktail
Prevention - vaccination
Viral infections
Viruses are the smallest microorganisims. They are always pathogens. They depend completely on cells to reproduce. They have an outer cover of protein, and sometimes lipid, and an RNA or DNA core. For infection to occur the virus first attaches to the host cell.
The viral DNA or RNA then separates from the outer cover (uncoating) and replicates inside the host cell in a process that requires specific enzymes
The host cell typically dies, releasing new viruses that infect other host cells
Viral Infection examples
Rubella - caused by rubella virus AIDS- caused by HIV Flu- caused by influenza virus Cold-caused by rhinovirus Pneumonia Measles Hepatitis
Herpesvirus
Family of DNA viruses that cause active or latent infections Herpes simplex 1 (HSV-1) Mouth Herpes simplex 2 (HSV-2) below waist Varicella-zoster virus (VZV) chicken pox Epstein-Barr virus (EBV) Mono Cytomegalovirus (CMV) Torch
Herpes Simplex
Causes oral herpes - cold sores (most common)
Causes genital herpes (second most common)
Easily transmitted via direct contact but can also be transmitted via indirect contact
HSV transmittion
Can be transmitted through contact with lesion or with contact of bodily fluids
Can also be transmitted during asymptomatic periods (asymptomatic viral shedding)
Can be transmitted from mother to child via birth canal
HSV S&S
Symptomatic phase includes sores on face, mouth, genitals, hands,
Symptomatic phase alternates with periods of remission
Virus tends to burn out over time
No treatment or vaccine
Symptoms antiviral meds
Prevention - condoms
Varicella-zoster virus
Causes chicken pox
Can persist in peripheral nervous system as latent infection
Reactivated as shingles in adults
chicken pox characterized by small, itchy vesicles all over body
In children, usually benign self-limiting disease
VZV
Can develop into life threatening encephalitis or pneumonia
Chicken pox in adults generally more painful, more scarring
Infection generally confers life long immunity
Prevention vaccination
VZV
Shingles aka herpes zoster
Characterized by unilateral painful blisters
Treatment - antiviral meds, painkillers
Prognosis - usually self -limiting within 5 weeks
EBV
Epstein-Barr virus
Cause infectious mononucleosis (‘mono’ or the “kissing disease”)
Characterized by fatigue, malaise, sore throat
Mild except for in IC compromised people, elderly, newborns
CMV
Cytomegalovirus
Very common
Causes symptoms similar to IM
Can cause congenital defects in developing embryo if maternal infection (TORCH)
Enterovirus
Members of the picornavirus family (small RNA viruses)
Shed in oral secretions, stool, blood, CSF (cerebral spinal fluid), nasal secretions
Affects millions of people per year
Symptoms can range from mild to severe
Include aseptic meningitis, acute paralysis, hand, foot and mouth disease, myocarditis, mild respiratory illness, conjunctivitis
Enters the mouth via the fecal-oral route, multiplies in tissues reaches the CNS
Example includes polio
Enterovirus
E.g. Poliovirus
Causes poliomyelitis (“polio”)
Highly contagious via fecal-oral route or direct contact
Symptoms can range from mild/asymptomatic to severe paralysis in children
Routine vaccination (1950s)
Influenza virus
Viral respiratory infection caused by the influenza virus
Symptoms include fever, cough, headache, nasal discharge and malaise
Mortality is common in high risk patients (immunocompromised, elderly, etc)
Rhinovirus
Causes the common cold
Upper respiratory tract infection (URTI)
Acute, afebrile, self-limiting viral infection
Involving upper respiratory symptoms such as runny nose, cough and sore throat
Fungal infections
Mycosis - any disease induced by a fungus
Fungi include yeasts and molds
Many fungi are opportunists and are not usually pathogenic except in a compromised host
Superficial - limited to outermost layers of skin and hair
Systemic- affect severely immunocompromised patients
Often have acute presentations with rapidly progressive pneumonia, fungemia, etc.
Fungal pneumonia
Caused by pneumocystis carinii/pneumocystis jirovecii
Extremely serious form of pneumonia
Causes significant mortality in IC and in healthy host
Yeast infections
Candida albicans
Normally populates GI tract, mouth, genitals
Overgrowth causes candidiasis (genitals) or thrush (mouth)
Sexually transmitted infections
Most common STIs Warts Chlamydia Herpes Gonorrhea Hepatitis Syphilis
Warts
Human papillomavirus causes anal or genital warts
HPV infection is linked to a higher incidence of cervical, anorectal and bladder cancers
Warts
Incidence: 5.5 million new cases/yr; incidence rapidly escalating
Transmission unprotected sexual contact; mother to newborn with delivery
Warts on genitals, anal region, cervix etc. 1- months after sexual contact with infected person
Warts DX
In women abnormal Pap smear can indicate possible cervical cancer
Can be removed using chemical ablative or surgical therapies
Recurrence is not uncommon
Chlamydia
Caused by bacteria: Chlamydia trachomatus
Incidence: 3 million new cases/yr
Most common STI caused by bacteria
Transmission: unprotected intercourse; infection of fetus in pregnancy
Chlamydia S&S
Symptoms - none or discharge, pain with intercourse, dysuria, bleeding can cause serious complications if untreated
Treatment -antibiotics
Gonorrhoea
Cause by bacteria - Neisseria gonorrhoeae
Incidence: 650,000 new cases/yr
Transmission: unprotected sex, infection of fetus in utero
Clinical manifestations in men: urethritis with discharge, increased urge to urinate and pain during urination
Gonorrhea S&S
Clinical manifestations in women: none or slight discharge and difficulty or pain during urination, pelvic pain, abnormal menstrual cycle.
Treatment - antibiotic
Can lead to cardiac valvular disease, arthritis (if untreated)
Hepatitis B
Caused by HBV (Hepatitis B virus)
Incidence: 77, 000 new cases/r
Transmission infected blood, sexual contact, breastfeeding
Symptoms - jaundice, arthralgias, rash, dark urine, anorexia, nausea, painful abdominal bloating, clay-colored stools fever
Can be prevented with Hep B vaccine
In unvaccinated, Hep B immunoglobulin and antiviral agents are used
Relapse on cessation of treatment is common
Syphilis
Incidence: 70,000 new cases/yr
STI caused by bacteria - Treponema pallidum (spirochete)
Transmission: unprotected sexual contact, contact with skin and mucous membranes, transplacental, blood transfusions
The bacteria enter through the mucous membranes or skin, reach the lymph notes and rapidly disseminate through the body.
Type of syphilis
Primary syphilis - painless lesion (chancre) at the site of inoculation 3-8 weeks after infection
Secondary syphilis - flu-like symptoms and rash 6 weeks to 2 years after infection
Tertiary syphilis -severe cardiovascular and CNS disturbances
Syphilis treatment
Syphilis can be latent and asymptomatic
Primary, secondary and latent syphilis can be cured with antibiotics
Tertiary syphilis can occur up to 20 years after initial infection and may cause irreversible cardiovascular neurological damage
Vaccination
A vaccine is any suspension containing antigenic molecules derived from a microorganism, given to stimulate an immune response to infectious disease
Vaccines can be administered intramuscularly, subcutaneously, intradermally, orally or intranasally.
Vaccines may be made from weakened or killed microorganisms inactivated toxins or immunologically active surface markers extracted or copied from microorganisms
