Communicable Diseases Flashcards
Communicable diseases, also known as
infectious diseases or transmissible diseases
illnesses that result from the infection, presence and growth of pathogenic (capable of causing disease) biologic agents in an individual human or other animal host
Communicable diseases
Leprosy
Synonym
Hansen’s disease
more formal name for leprosy;
sometimes used to avoid the dreaded name
Hansen’s disease
Leprosy Etiologic agent:
Mycobacterium leprae
Leprosy Reservoir:
Humans
Leprosy Transmission:
Aerosol spread of nasal secretions; cannot cross intact skin
Leprosy incubation period:
3 to 5 years (shorter for PL than ML)
- roughly the same as ___________ leprosy (PL) in the WHO leprosy classification system.
- characterized by discolored regions of the skin that have lost sensation
tuberculoid (neural) form
- paucibacillary
characterized by one or a few hypopigmented or hyperpigmented skin macules that exhibit loss of sensation (anesthesia) due to infection of the peripheral nerves supplying the region.
Paucibacillary (PB), or tuberculoid
- much the same as _____________ (ML) in the WHO system
- skin cells are infected, and disfiguring nodules form all over the body.
lepromatous (progressive) form
- multibacillary
Therapy for PL and ML leprosy
PL: Dapsone and Rifampicin for 6 months
ML: Dapsone, Rifampicin, and Clofazimine for 24 months
leprosy prevention
BCG vaccination: provides variable protection (34% to 80%)
- the word is from the Latin for rage or madness
- a disease that almost always results in fatal encephalitis.
Rabbies
Rabbies Reservoir:
Wild and domestic canines, skunks, raccoons, insectivorous bats
Rabbies Transmission:
Animal (dog) bite (rabies virus in saliva)
Incubation Period of Rabies:
average of 30 to 50 days; 6 years have been reported
Rabies virus enters a motor neuron and travels, at the rate of ________ mm/day, along peripheral nerves to the CNS, where it causes encephalitis.
15 to 100
- begins with fever, nausea, vomiting, headache, fatigue, and other nonspecific symptoms (mild and varied, resembling several common infections.)
- Some patients continue to experience pain, burning, prickling, or tingling sensations at the wound site.
The prodromal phase of rabbies
- the first acute signs of neurological involvement are agitation, disorientation, seizures, and twitching.
The furious phase of rabies
patient is not hyperactive but paralyzed, disoriented, and stuporous.
The dumb (numb or paralytic) phase
- detection of the viral antigen
- nearly 100% sensitive and highly specific.
- can be done on saliva samples, blood, CSF, and skin; post- mortem samples are
usually taken from the brain.
direct fluorescent-antibody (DFA) test
- requires only the use of an ordinary light microscope and has a sensitivity and specificity equivalent to the standard DFA test.
- For less- developed parts of the world by CDC
- rapid immunohistochemical test (RIT)
is one of the few infectious diseases for which a combination of passive and active postexposure immunization is indicated and successful.
- Rabies
- Throughout human history, including prehistoric times, __________ has been one of the greatest afflictions, in the same ranks as bubonic plague, influenza, and tuberculosis.
Malaria
Malaria Etiologic agent:
Plasmodia
Sexual cycle phase of malaria is called __________ because ____________ are produced. Occurs primarily in mosquitoes
- Sporogony
- sporozoites
Asexual cycle phase of malaria is called _______________ because __________ are made. Occurs in humans, the intermediate host
Schizogony
schizonts
important cause of the common cold, probably second only to ___________ in frequency.
Rhinoviruses.
In 2002, a new disease, an atypical pneumonia called _______________, emerged.
severe acute respiratory syndrome (SARS)
In 2012, another severe pneumonia called _______________ emerged.
Middle East respiratory syndrome
SARS originated in and spread rapidly to other countries.
As of 2016, there have been ______ cases and ________ deaths—a fatality rate of approximately 9%.
China in November 2002
8300 cases
785 deaths
a new human coronavirus that caused an outbreak of serious, often fatal pneumonia in Saudi Arabia and other countries in the region in 2012–2013.
Middle East Respiratory Syndrome (MERS)
Close contact with _______ appears to be the mode of transmission of MERS to humans.
camels
the primary HIV found worldwide in humans
is genetically related to another Lentivirus, _____________
HIV- 1
- simian immunodeficiency virus (SIV)
is carried by monkeys, mangabeys, and chimpanzees in central Africa
SIV
Earliest known sample of HIV comes from
Kinshaa, Democratic Republic of the Congo, in 1920
HIV spread through:
- Transportation
- High population of migrants
- Sex trade in Kinshaa
HIV spikes attach to ________________ on host cells
CD4 and corereceptors
is transcribed to DNA by reverse transcriptase
Viral RNA
becomes integrated into the host chromosome to direct synthesis of new viruses or to remain latent as a provirus
Viral DNA
HIV evades the immune system:
- In latency
- In vacuoles
- By using cell- cell fusion
- By antigenic change
HIV is categorized by clinical phases:
* About 2 months following initial infection, the population of HIV in the blood peaks at about 10 million per ml
* Population of CD4+ T cells plunges during acute phase of HIV infection, then recovers as immune response appears
* Seroconversion: detectable antibodies against HIV appear. Immune response causes rapid decline in HIV population
* HIV in blood stabilizes at steady rate of 1000 to 10,000 per ml.
- Phase 1 (asymptomatic/ chronic lymphadenopathy)
HIV is categorized by clinical phases:
* CD4+ T cell population declines steadily
* HIV replication continues but at a relatively low level, probably controlled by CD8+ T cells; occurs mainly in lymphatic tissue
* Few diseases/ conditions:
- Candida albicans (in the mouth, throat, or vagina)
- Phase 2 (Symptomatic; early indications of immune failure)
- Three Stages of HIV:
Begins 2 to 4 weeks after infection - Mononucleosis-like picture of fever, lethargy, sore throat, and generalized lymphadenopathy
- Maculopapular rash on the trunk, arms, and legs (except palms and soles)
- Leukopenia, but the number of CD4 cells is usually normal
Early, Acute stage
What is the stage of this HIV?
- flu-like symptoms that occur days to week after contracting HIV
Acute HIV
What is the stage of this HIV?
- also known as the latent or asymptomatic stage; can last for several years
Chronic HIV
What is the stage of this HIV?
- occur when CD4 cell count falls below 200 cells/mm3; makes a person vulnerable to opportunistic infections and AIDS-defining conditions
AIDS
- Sexual contact
- Heterosexual intercourse is the primary method of HIV transmission
- Breast milk
- Contaminated needles
- Transplacental infection
- Artificial insemination
- Blood transfusion
HIV TRANSIMISSION
- Transmission can be reduced by biomedical, behavioral, and structural interventions Current therapeutic agents target cell entry and the virus enzymes, including reverse transcriptase, integrase, and protease
- Vaccine development is difficult because there are different antigenic clades and the virus remains inside host cells.
Preventing and Treating Aids
False negative results when testing is performed before the onset of detectable antibodies, a period called a __________
window
DIAGNOSIS:
* Antibody Tests
* Presumptive test/ Initial screening
* 1% can be false- positive
Enzyme- linked immunosorbent assay (ELISA)
DIAGNOSIS:
* Antibody Tests
* Confirmatory test / definitive test
Western blot (Immunoblot) analysis
To rule out this possibility, persons who test negative but are at some risk for exposure should be tested a second time _____ months later.
3 to 6
is caused by the Zika virus, or ZIKV, a member of the Flaviviridae.
Zika virus disease (ZVD)
ZIKV was first discovered in _____ in rhesus monkeys and is named after the Zika forest in Uganda
1947
ZIKV infection during pregnancy greatly increases the risk of fetuses and infants developing a condition called ________.
microcephaly
The most common signs and symptoms of ZVD, which last about a week, affect about 20% of infected individuals. They are usually mild and include ______, ___________, ______ and _____________, ________, __________, and _____________ Because people usually do not become ill enough to require hospitalization, they may not even realize that they are infected.
fever, headache, muscle and
joint pain, malaise, skin
rash, and conjunctivitis.
Diagnosis of ____ is confirmed by reverse transcriptase PCR, and treatment involves rest, intake of sufficient fluids, and pain and fever reduction with common medications.
ZVD
- DIAGNOSING INFECTIOUS DISEASES
- Requirements:
- Taking a complete patient history
- conducting a thorough physical examination
- evaluating the patient’s signs and symptoms
- implementing the proper selection, collection, transport, and
processing of appropriate clinical specimens
- Three Components of Specimen Quality
- proper selection of the specimen
- proper collection of the specimen
- proper transport of the specimen to the laboratory
- Consequences of Improperly Collected Specimens
- the etiologic agent may not be found or may be destroyed
- overgrowth by indigenous microflora may mask the pathogen
- contaminants may interfere with the identification of pathogens and the diagnosis of the infectious disease
- General Precautions in Collecting Clinical Specimens
- The specimen must be properly selected
- The specimen must be properly and carefully collected
- The material should be collected from a site where the suspected pathogen is most likely to be found and where the least contamination is likely to occur
- Specimens should be obtained before antimicrobial therapy has begun. If this is not possible, the laboratory should be informed as to which antimicrobial agent(s) the patient is receiving
considered to be the only bacterium that grows in the peripheral nervous system.
Mycobacterium leprae
recently discovered (in 2008) leprosy-causing bacterium _____________, which is found mostly in Mexico and the Caribbean.
M. lepromatosis
first isolated and identified around 1870 by Gerhard A. Hansen of Norway;
Mycobacterium leprae
2 forms of leprosy
- Tuberculoid (neural)
- Lepromatous (progressive)
2 forms of leprosy
- Tuberculoid (neural)
- Lepromatous (progressive)
- Patients with this type of leprosy have had the least effective cell-mediated
immune response, and the disease has progressed from the tuberculoid stage.
Lepromatous (progressive) form
Mucous membranes of the nose tend to become affected, and a _______________ is associated with this type of leprosy.
lion-faced appearance
• Deformation of the hand into a clawed form and considerable necrosis of tissue can also occur
• Progression of the disease is unpredictable, and remissions may alternate with rapid deterioration.
lepromatous (progressive) form of leprosy
- Hypopigmented or reddish skin lesion(s) with loss of sensation
- Thickening of the peripheral nerves with loss of sensation
Leprosy
M. Leprae remain viable for ______ in dried nasal secretions, and about ________ in moist soil
9 days
6 weeks
rabies virus is a member of the genus ____________ having a characteristic _______ shape
Lyssavirus
bullet shape
rabies virus is a member of the genus ____________ having a characteristic _______ shape
Lyssavirus
bullet shape
are single-stranded RNA viruses with no proofread- ing capability, and mutant strains develop rapidly.
Lyssaviruses
(lyssa, from the Greek for frenzy)
When the CNS becomes involved, the patient tends to alternate between periods of agitation and intervals of calm.
The prodromal phase of rabbies
- a frequent symptom is spasms of the muscles of the mouth and pharynx that occur when the patient feels air drafts or swallows’ liquids. In fact, even the mere sight or thought of water can set off the spasms
The furious phase of rabies
Throughout this phase, the patient is fully coherent and alert.
furious phase of rabies
The rabies wound is infused with ______________________ to impede the spread of the virus, and __________ is also injected intramuscularly to provide immediate systemic protection. A full course of vaccination is started simultaneously. The current vaccine of choice is the __________________.
human rabies immune globulin (HRIG)
globulin
human diploid cell vaccine (HDCV)
The rabies wound is infused with ______________________ to impede the spread of the virus, and __________ is also injected intramuscularly to provide immediate systemic protection. A full course of vaccination is started simultaneously. The current vaccine of choice is the human diploid cell vaccine (HDCV).
human rabies immune globulin (HRIG)
As the dominant protozoan disease, Malaria threatens ____ of the world’s population every year.
40%
The origin name of Malaria is from the Italian words _____, ______, and ______, air
mal, bad, and aria, air.
The superstitions of the Middle Ages explained that ______ or ________ and vapors arising from swamps caused malaria, because many victims came down with the disease after this sort of exposure.
evil spirits or mists
more common Plasmodia
P. vivax
P. falciparum- causes more severe malaria
P. ovale
P. malariae
P. knowlesi- in Southeast Asia
Human-to-human transmission occurs, and some patients with SARS are thought to be “___________.”
“super- spreaders”
The __________________ appears to be the natural reservoir for CoV-SARS, with the ___________ serving as an intermediate host.
horseshoe bat
civet cat
another name for MERS coronavirus (MERS-CoV)
human coronavirus- EMC (HCoV-EMC).
is a retrovirus with single-stranded RNA, reverse transcriptase, and a phospholipid envelope with gp 120 spikes
HIV
