chapter 18 Flashcards
18.1 The Cardiovascular and Lymphatic Systems and Their Defenses
direct connection between two systems/circulations occurs at points near the heart where large lymph ducts empty their fluid into veins
upper chambers of the heart
atria
lower chambers of heart
ventricles
the heart is encased in a fibrous covering, the __________, which is an occasional site of infection
pericardium
three layers of the wall of the heart from: outer to inner
epicardium –> myocardium –> endocardium
arteries carry ________ away from the heart under relatively high pressure, and branch into arterioles
oxygenated
Veins begin as smaller venules as they coalesce into veins, and carry blood ______ the heart
toward
what are the walls of veins and arteries made of
three layers:
innermost: endothelium
middle: connective tissue and muscle fibers
outermost: thin layer of connective tissues
capillaries, the smallest vessles, have walls made up of only one layer of _________
endothelium
lymphatic system serves to ________ fluid that has left the blood vessels and entered tissues, _____ it of impurities and infectious agents and return it to blood
collect
filter
bloodstream infections are called _________ infections
systemic
modes of defense in the bloodstream
leukocytes (5000-10,000 WBC per microliter of blood)
ie. macrophages, neutrophils, lymphocytes
18.2 Normal Biota of the Cardiovascular and Lymphatic Systems
closed systems like the nervous system, with no normal access to external environment
long believed that the cardiovascular and lymphatic systems contain _____ normal biota
no
recent studies from the Human Microbiome Project have suggested that (regarding biota in bloodstream)
the bloodstream is not completely sterile, even during periods of apparent health
—>there is evidence that the blood cells, especially WBCs, do contain bacteria of various types
a patient has been dx’d with inflammation of the inner lining of the heart, secondary to a bacterial infection. what is the term for this condition?
endocarditis
cardiovascular system defenses and biota recap
blood-borne components of innate and adaptive immunity-including phagocytosis, adaptive immunity
normal biota= sparse, mostly WBCs
lymphatic system defenses and biota recap
numerous immune defenses reside here
normal biota: unclear
18.3 Cardiovascular and Lymphatic System Diseases Caused by Microorganisms
it can be difficult to categorize cardio and lymph infections according to clinical presentation because most of these conditions are systemic
Malaria
in same rank as bubonic plague, influenza, and tuberculosis
dominant protozoal disease, threatens 40% of the world’s population every year
malaria —>
mal- bad
aria- air
malaria S/S
10-16 day incubation period
- after inc. period the first symptoms are malaise, fatigue, vague aches, and nausea with or without diarrhea
- followed by bouts of chill, fever, and sweating
- -> these symptoms occur as 48 or 72-hour intervals, as a result of synchronized rupturing of RBCs
- complications of malaria are hemolytic anemia from lysed blood cells, and organ enlargement and rupture due to cellular debris that accumulate in the spleen, liver, and kidneys
Patients with Falciparum malaria, most virulent type, often display persistent fever, cough and weakness for weeks without relief
—> one of most serious complications is cerebral malaria, in which small blood vessels in the brain become obstructed due to increased ability of RBCs to adhere to vessel walls (cytoadherence- induced by protozoan)
Malaria causative agents
Plasmodium species are protozoa in the sporozoan group, over 200 species but only 5 are known to infect humans:
Plasmodium falciparum (responsible for vast majority of deaths) P. vivax P. ovale P. malariae P. knowlesi
Development of malarial parasite is divided into two distinct phases:
Asexual Phase - carried out in the human
Sexual Phase - carried out in the mosquito
Malaria transmission and epidemiology
Biological vector (mosquito) (female Anopheles mosquito) Vertical
Spread is mostly restricted to a belt extending around the equator
Approx. 200 million new cases are reported each year, about 90% in Africa
Most frequent victims are children and young adults, of whom 500,000 die annually.
Particular form of the malarial protozoan causes damage to the placenta in pregnant women, leading to excess mortality among fetuses and newborns
–> most cases acquired in endemic areas, but locally trans’d infections are on the rise
Malaria pathogenesis and virulence factors
multiple life stages, multiple antigenic types; ability to scavenge glucose, GPI, cytoadherence
invasion of merozoites into RBCs leads to release of fever-inducing chemicals into the bloodstream (chills and fever often occur in cyclic pattern)
- Plasmodium metabolize glucose at high rate = hypoglycemia in host
- Damage to RBCs results in anemia
- Accumulation of malarial products in liver and immune stimulation in the spleen can lead to enlargement of these organs
- Individual protozoa within host can express distinctly different surface antigens making it difficult for the host immune system to battle
Lifecycle of Malarial Parasite
- Asexual phase (and infection) begins when an infected Anopheles mosquito injects saliva containing anticoagulant into a capillary in preparation for taking a blood meal —> inoculates blood with motile, spindle-shaped asexual cells called sporozoites
- Sporozoites circulate through the body and migrate to the liver quickly; inside the liver cells they undergo asexual division called schizogony; causes eruption of liver cells and release of daughter cells “merozoites”
- During the erythrocytic phase, merozoites attach to special receptors on RBCs and invade them, producing a cell called schizont which is filled with more merozoites; bursting RBCs liberate merozoites to infect more cells and eventually merozoites differentiate into specialized gametes called macrogametocytes (F) and microgametocytes (M)
- –> end of life cycle in humans - Sexual phase (sporogony) occurs when a mosquito draws infected red blood cells into her stomach, and in the stomach microgametocytes (M) release gametes that fertilize the macrogametocytes (F); the resultant diploid cell (ookinete) implants into the stomach wall of the mosquito becoming an oocyst which undergoes mitotic division releasing sporozoites that migrate into salivary glands of bug. —-> mosquito goes on to infect next person
Malaria Culture/dx
can be diagnosed definitively by the discovery of a typical stage of Plasmodium in stained blood smears
Newer Ag-specific tests have been developed, but the smears are still considered golden standard
–> other indications are the patient’s residence or travel in endemic areas and symptoms such as recurring chills, fever, and sweating
After returning from international travel, a 4 y/o female is dx’d with falciparum malaria. All of the following complications may be associated with this disease except:
a. splenic rupture
b. acute kidney injury
c. altered mental status
d. peptic ulcer
e. anemia
d. peptic ulcer
Malaria prevention
long-term mosquito abatement and human chemoprophylaxis
- abatement includes: elimination of standing water, spraying of insecticides
- using netting, screens, and repellants, remaining indoors at night, taking weekly doses of prophylactic drugs
- western travelers to endemic areas are often prescribed antimalarials for duration of their trip
- WHO focus on efforts to distribute bed nets and teaching people how to dip nets into insecticide (estimated to reduce childhood mortality from malaria by 20%)
Vaccine:
-first approved for malaria prevention is RTS,S and was tested on children in three African countries beginning in 2019, in 2021 it is scheduled for widespread use on that continent
CRISPR:
- technique used to engineer a gene into mosquitos that makes them resistant to carrying malaria (gene will be passed onto bug offspring)
- –> could potentially eliminate transmission altogether
Malaria treatment
Quinine has been OG tx for malaria for a long time
- Chloroquine, the least toxic type, is used in nonresistant forms of disease
- The protozoan has developed resistance to nearly every drug used for tx
Artemisinin Combination Therapy (ACT) is also recommended as first line tx
-Artemisinin is a plant-derived compound from wormwood tree, discovered in 1972 by a Chinese Scientist - she was later awarded the Nobel Prize for this life-saving find
HIV Infection and AIDS
HIV S/S
a spectrum of clinical signs and symptoms is a associated with human immunodeficiency virus (HIV)
Symptoms are directly tied with two things:
- the level of virus in the blood
- the level of T cells in the blood
HIV S/S Initial Infection
characterized by vague mononucleosis-like symptoms that soon disappear
(fatigue, headache, fever, etc.)
-this phase corresponds to the initial high levels of virus (the green line on graph)
-antibodies are not yet abundant
-fatigue, diarrhea, weight loss, and neurological changes
BUT most patients first notice infection b/c of one or more opportunistic infections or neoplasms (cancers)
HIV S/S Second Phase
virus numbers in blood drop dramatically and antibody levels become detectable
-CD4 T cells begin to decrease in number
HIV S/S third phase
long period of asymptomatic infection ensues
- during this time, which can last from 2-15 years, lymphadenopathy (swollen lymph nodes) may be prominent symptom
- during the mid- to late- asymptomatic period, the number of T cells in the blood is steadily DECREASING
- once the T cell level reaches a (low) threshold, the symptoms of AIDS ensue
HIV S/S Fourth phase
Once T cells drop below 200 cells/uL, AIDS results
-note that even though antibody levels remain high, virus levels in the blood begin to rise
AIDS defining illness
list some AIDS defining illnesses
ie. opportunistic infections that may indicate to patients/doctors they have HIV/AIDS
Cardiovascular/Lymphatic System:
- Coccidioidomycosis
- Cytomegalovirus
- Burkitt’s Lymphoma
- Mycobacterium tuberculosis
Skin or Mucous Membranes:
- Cytomegalovirus retinitis
- Herpes simplex chronic ulcers
- Kaposi’s sarcoma
Nervous System:
- HIV encephalopathy lymphoma
- Toxoplasmosis of the brain
- Cryptococcus
any many more in other systems
some of the most virulent complications in AIDS are ____________; lesions occur in the brain, meninges, spinal column, and peripheral nerves.
Patients may show some degree of memory loss, withdrawal, spasticity, sensory loss, and progressive AIDS dementia
neurological
HIV Causative Agent
Retrovirus in the genus Lentivirus
-many retroviruses have the potential to case cancer and produce dire, often fatal diseases, and are capable of altering host DNA in profound ways
- contain features typical of enveloped RNA viruses
- –> outermost component is a lipid envelope with transmembrane glycoprotein spikes that mediate viral adsorption to the host cell
HIV can only infect host cells that present the required receptors, which is a combo receptor consisting of the CD4 marker plus a coreceptor called CCR-5
why are retroviruses called that
they reverse the usual order of transcription
-contain an unusual enzyme called reverse transcriptase (RT) that catalyzes the replication of double-stranded DNA from single-stranded RNA
HIV pathogenesis and virulence factors
enters a mucous membrane or the skin and travels to dendritic cells beneath the epithelium
- here the virus grows and is shed from the cell without killing it
- virus is amplified by macrophages in the skin, lymph organs, bone marrow, and blood
—> HIV infects and destroys many of the very cells needed to combat it including the helper (T4 or CD4) class of lymphocytes, monocytes, and macrophages, and even B lymphocytes
*CREATES SYNCYTIA
HIV Transmission
occurs mainly through two forms of contact:
- sexual contact
- transfer of blood or blood products
—>babies can also be infected before or during birth, as well as by breastfeeding
HIV is not transmitted through saliva, and is far more sensitive to heat and disinfectants than Hep B
-possibility of transmission when in contact with amniotic fluid, synovial fluid, and spinal fluid
- semen and vaginal secretions also harbor free virus and infected WBCs
- the virus can be isolated from urine, tears, swear, and saliva in lab, but they are in such small amounts that the fluids are not considered infectious
HIV Epidemiology
since the AIDS epidemic in the early 1980s, approx. 35 million people have died globally
-est. 37.9 million infected individuals currently
—> tx of HIV infected mothers with an anti-HIV drug has dramatically decreased the rate of maternal-to-infant transmission of HIV during preg
- Cuba became first country to eliminate mother-to-child transmission of HIV
- evidence suggests that giving mothers protease inhibitors reduces the transmission rate by about 1%
HIV Culture/dx
most initial testing is based on detection of antibodies specific to the virus in serum or other fluids
—> newer tests detect antibodies to the virus and viral antigens simultaneously
- False negatives can occur when testing is performed too early in infection
- -> takes a few weeks for antibodies to be detectable in body fluids, so persons who test neg but feel they have been exposed should be tested a second time 3-6 months later
Positive tests require follow up with more specific testing
- an antibody differentiation immunoassay determines whether the infection is with HIV-1 or HIV-2
- -> uncertain results are followed by an HIV nucleic acid amplification test (NAAT)
HIV AND AIDS dx criteria
- They are positive for virus and 2. they meet one of the additional criteria:
- they have a CD4 (helper T cell) count of fewer than 200 cells per microliter of blood
- their CD4 cells account for fewer than 14% of all lymphocytes
- they experience one of more of the CDC-provided list of AIDS-defining illnesses (ADIs)
HIV prevention
- assume all sexual partners are infected unless otherwise known
- don’t share needles/syringes that are used
- use condoms
- Preexposure prophylaxis (PrEP)
HIV tx
no cure
-new drugs improve quality of life
first effective developed drugs:
synthetic nucleoside analogs (reverse transcriptase inhibitors) such as
-Azidothymidine (AZT)
One of the latest additions to the arsenal:
Enfuvirtide (Fuzeon), fusion inhibitor (prevents virus from fusing with the membrane of target cells, thereby stopping infection altogether
Protease Inhibitors:
HIV Enzyme (protease) inhibited in final assembly and maturation of the virus
ie. Indinavir (Crixivan) and Ritonavir (Norvir) and Amprenavir (Agenerase)
Endocarditis
inflammation of the endocardium, or inner lining of the heart
-most of the time refers to infection of the valves of the heart, often the mitral or aortic valve
- acute and subacute, both primarily bacterial
- -> in rare cases could be causes by fungi or viruses
- -> physical trauma can also cause inflammation
Endocarditis S/S
same for acute and subacute except in subacute they develop more slowly and are less pronounced
- fever
- weakness/fatigue
- joint pain
- edema (of legs, feet, and abdomen potentially)
- anemia
- abnormal heartbeat
- sx similar to a heart attack like shortness of breath and chills
- petechiae over the upper half of body and under fingernails (splinter hem.)
- red, painless spots on palms and soles of feet (Janeway lesions)
- small painful nodes on pads of fingers and toes (Osler’s nodes)
in subacute cases, an enlarges spleen may have developed over time
-cases over long periods of time can lead to clubbed fingers and toes due to lack of O2 inblood
_________ endocarditis is most often the result of an overwhelming bloodstream challenge with bacteria; accumulations of bacteria on the valves, called __________, hamper their function and can lead directly to cardiac malfunction and death.
Pieces of bacterial ___________ can also break off and create emboli in vital organs
acute
vegetation
vegetation
Acute Endocarditis causative agents
40% of acute cases are causes by S. aureus
other agents are S. pyogenes, S. pneumoniae, Enterococcus, and Pseudomonas aeruginosa, as well as other host bacteria
S. aureus is most DANGEROUS cause of endocarditis
Transmission and Epi of Acute Endocarditis
most common route is parenteral
-IV and subq drug users have been a growing risk group
traumatic injuries and surgical procedures can also introduce the large number of bacteria required for the acute form of endocarditis
—>heroin epidemic currently sweeping the US has led to large increases in the incidence of acute endo. by S. aureus
subacute endo causative agents
- almost always preceded by some form of damage to the heart valves or by congenital malformation = irregularities encourage attachment of bacteria and biofilms
- people who have suffered rheumatic fever are at risk
Alpha-hemolytic streptococci such as Streptococcus sanguis, S. oralis, and S. mutans
Subacute Endo trans and epi
minor disruptions in the skin or mucous membranes such as those caused by vigorous toothbrushing, dental procedures, or relatively minor cuts and lacerations can introduce bacteria in the bloodstream and lead to valve colonization
Subacute Endo Prevention
prophylactic antibiotics for patients before surgery
Culture/dx and treatment of endocarditis
blood culture = dx
tx = vancomycin surgery for acute may be necessary tx = surgery may be necessary for subacute too
Septicemia
Causative Organism: bacteria or fungus, often MRSA, increasingly Candida auris
Trans: parenteral, endogenous transfer
V Factors: cell wall or membrane components
Culture/dx: blood culture, deep sequencing, checking for blood marker called procalcitonin (early indicator)
Prevention:
Tx: broad-spectrum antibiotic until identification and susceptibilities tested; Empiric Therapy
Epi Feats: US: 1.7million cases/year
S/S of Sepsis
fever is prominent feature
- patient appears very ill, and may have altered mental state
- shaking chills, gastrointestinal symptoms
- increased breathing rate often accompanied by resp. alkalosis (increased tissue pH due to breathing disorder)
- low BP (caused by inflammatory response to infectious agents in the blood stream, which leads to loss of fluid from vasculature)
- –>low BP is more DANGEROUS feat of this disease, often culminating in death
Sepsis: Pathogenesis and V Factors
gram neg bacteria multiplying in the blood release large amounts of endotoxin into the bloodstream, stimulating a massive inflamm. response mediated by a host of cytokines
–> leads to crash in BP, a condition called ENDOTOXIC SHOCK
gram pos can stimulate a similar cascade when fragments of their cell walls are released into the blood
Sepsis: Trans and Epi
parenteral intro via IV lines or surgical procedures
infections may arise from UTIs, or from renal, prostatic, pancreatic, or gallbladder abscesses
Plague
Causative Organism: Yersinia pestis (G-)
Trans: vector, biological (prairie dogs); droplet contact (pneumonic) and direct contact with body fluids
V Factors: Capsule, plasminogen activator
Culture/dx: rapid genomic methods; Yersinia pestis displays unusual bipolar staining that makes it look like a safety pin
Prevention: Flea and/or animal control; vaccine available for high risk individuals
Tx: Gentamicin or doxycycline
Epi Feats: US: endemic in all western and southwestern states; internationally, 95% of human cases occur in Africa, including Madagascar
CATEGORY A BIOTERRORISM AGENT
Plague S/S
Pneumonic Plague: resp. disease
Bubonic Plague: injected by bite of flea, enters lymph, and filtered by local lymph node
-infection causes inflammation and necrosis of the node, resulting in a swollen lesion called bubo, usually in the groin or axilla
-incubation is 2-8 days, ending abruptly with ONSET OF: chills, headache, nausea, weakness, and tenderness to bubo
Systemic Plague: result of massive bacterial growth from other two infections
-results in disseminated intravascular coagulation, subcutaneous hemorrhage, and purpura that may degenerate into necrosis and gangrene
mortality rates with tx can reach up to 15%; once disease has progressed to systemic = with tx MR is 30-50% and without tx = 100%
how many bacteria are required to cause plague infection?
Hint: small number
3-50 cells
Tularemia
Causative Organism: Francisella tularensis (G-) (zoonotic disease ie. rabbit fever)
Trans: Biological vector (tick); also direct contact with body fluids from infected animal; airborne
V Factors: intracellular growth
Culture/dx: culture is dangerous to lab workers and not reliable; serology most often used; fine needle aspirations of lymph nodes sometimes used
Prevention: avoiding contact; postexposure prophylaxis
Tx: Gentamicin or streptomycin
Epi Feats: US: several hundred cases annually; internationally, 500,000 cases annually
CATEGORY A BIOTERRORISM AGENT
Tularemia S/S
incubation period ranging from a few days to 3 weeks
-acute symptoms of headache, backache, fever, chills, coughing, and weakness
further clinical manifestations are tied to portal of entry
-include ulcerative skin lesions, swollen lymph glands, conjunctival inflammation, sore throat, intestinal disruption, and pulmonary involvement
death rate in most serious forms of disease is 30%, but proper tx with gentamicin or streptomycin = mortality of zero
Tularemia Transmission and Epi
-rabbits and rodents (muskrats and ground squirrels) are the chief reservoirs, other wild animals (skunks, beavers, foxes, opossums) and some domestic animals are implicated as well
chief route of trans in the past has been skinning rabbits, but the most common mode now is via tick bites, but mosquitos, flies, and mites also can transmit
aerosols
often considered one of the most infectious of all bacteria
Lyme Disease
Lyme S/S
slow-acting, and slowly evolves into a progressive syndrome that mimics neuromuscular and rheumatoid conditions
- early symptom in some cases is a rash that looks like a bull’s eye, it is called erythema migrans (has a raised reddish ring)
- –> can be flat and scaly too, or it can be pustular
other sx: fever, headache, stiff neck, and dizziness
–> if not treated can develop into second stage where cardiac and neurological symptoms such as facial palsy can develop or crippling arthritis
Lyme Disease
Causative Organism: Borrelia burgdorferi and closely related species (G-) - unusual spirochetes
Trans: biological vector (tick - Ixodes: black legged tick)
V Factors: antigen shifting (provokes huge immune response that is ineffective due to antigen shifting), adhesins
Culture/dx: In late Lyme disease: for Ab, Western Blot (double check); acute and convalescent sera testing; bulls eye rash
Prevention: tick avoidance (protective clothing, DEET)
Tx: Doxycycline and/or amoxicillin (2 weeks)
Epi Feats: Endemic in North America, Europe, and Asia; approx. 300,000 new cases/year in the US; only 10% diagnosed/reported
Infectious Mononucleosis
“Mono”
can be caused by a number of bacteria or viruses, but the main causative agent is Epstein-Barr virus (member of the herpes family)
Infectious Mononucleosis
Causative Organism: Epstein-Barr Virus
Trans: direct, indirect; parenteral
V Factors: latency, ability to incorporate into host DNA
Culture/dx: differential blood count, monospot test for heterophile antibody, specific ELISA
Prevention: n/a
Tx: Supportive
Distinct Feat: lifelong persistence
Epi Feats: US: 500 cases per 100,000 per year
Mono S/S
sore throat, high fever, and cervical lymphadenopathy (which develop after a long incubation period of 30-50 days)
- many patients also get gray-white exudate in the throat, skin rash, and enlarged spleen and liver
- NOTABLE SIGN of mono is leukocytosis (increase in WBCs)
- FATIGUE
Infectious Mononucleosis
Trans and Epi
more than 90% of the world’s pop. is infected with EBV
-in general the virus causes no noticeable sx, but the time of life when the virus is first encountered seems to matter
direct oral contact and contamination with saliva are the principal modes of transmission, although transfer through blood transfusions, sexual contact, and organ transplants is possible
Mono
Prevention and tx
asymptomatic relief of fever and sore throat
occasionally rupture of spleen necessitates immediate surgery to remove it
Hemorrhagic Fever Disease ie. Ebola
a number of agents that infect the blood and lymphatics cause extreme fevers, some of which are accompanied by internal hemorrhage
- presence of virus in bloodstream cause capillary fragility and disrupts blood-clotting system, which leads to various degrees of pathology, including death
- all of these virus are RNA ENVELOPED VIRUSES
The Diseases:
- Yellow fever
- Chikungunya
- Dengue fever
- –> all spread by Aedes genus of mosquito and common in South America and Africa
trials being conducted in which male A. aegypti mosquitoes infected with the bacterium Wolbachia are being released in areas with heavy dengue burden (causes mating eggs not to be delivered, and the mosquito population is reduced)
Hemorrhaging Fever Diseases: Yellow Fever Virus
endemic in Africa and South America; more frequent in rainy climates
-carried by Aedes mosquitos
V Factor: disruption of clotting factors
Culture/Dx: ELISA, PCR
Prevention: Live attenuated vaccine
Tx: supportive
Distinct Feats: accompanied by jaundice
Hemorrhaging Fever Diseases: Dengue Fever
Trans: Aedes mosquito
V Factors: disruption of clotting factors
Culture/dx: Rise in IgM titers
Prevention: new vaccine available but has special requirements
Tx: supportive
Distinct Feats: “breakbone fever” so named due to severe pain in some forms
Epi Feats: Category A Bioterrorism Agents
Hemorrhaging Fevers: Chikungunya
Causative Organism:
Trans: Aedes
V Factors: disruption of clotting factors
Culture/dx: PCR
Prevention: vaccine in development
Tx: supportive
Distinct Feats: arthritic symptoms
Epi Feats: first local trans in US in 2014
Ebola and/or Marburg
Causative Organism: Ebola virus, Marburg virus
Trans: direct contact, body fluids
V Factors: disruption of clotting factors
Culture/dx: PCR, viral culture (conducted at CDC)
Prevention: New Ebola vaccine suitable for epidemic situations
Tx: new drugs developed during the ongoing outbreak in the DRC
Distinct Feats: massive hemorrhage, rash sometimes present
Epi Feats: Category A Bioterrorism Agent; major Ebola outbreak 2014-2016
Hemorrhaging Fever Diseases: Lassa Fever
Causative Organism: Lassa fever virus
Trans: droplet contact (aerosolized rodent excretions), direct contact with infected fluids
V Factors: disruption of clotting factors
Culture/dx: ELISA
Prevention: avoiding rats, safe food storage
Tx: Ribavirin
Distinct Feats: chest pain, deafness as long-term sequelae
Epi Feats: Category A Bioterrorism Agent
Non-hemorrhagic Fever Diseases
syndromes characterized by high fever, but not the capillary fragility seen in hemorrhagic fever diseases
-all diseases in this section, except for Babesiosis, are caused by bacteria
NHFD: Brucellosis
“Malta Fever, Bang’s Disease, Undulant Fever”
Causative Organism: Brucella species (G-) (B. abortus, B. suis, B. melitensis)
Trans: direct contact, airborne, parenteral (needlesticks)
V Factors: intracellular growth; avoidance of destruction by phagocytes; enters damaged skin via mucous membranes and is taken up by phago cells
Culture/dx: Gram stain of biopsy material
Prevention: animal control, pasteurization of milk
Tx: Doxycycline plus gentamicin or streptomycin
D Feats: undulating fever, muscle aches
Epi Feats: internationally 500,000 cases per year
S/S: focal lesions in the liver, spleen, bone marrow, and kidney; fluctuating pattern of fever
NHFD: Q Fever
Causative Organism: Coxiella burnetii (G-)
Trans: airborne, direct contact, foodborne
- primary POE: lungs, skin, conjunctiva, and GI tract
V Factors: Endospore like structure
Culture/dx: serological tests for antibody
Prevention: vaccine for high risk population
Tx: Doxycycline
D Feats: airborne route of transmission, variable disease prevention; sometimes complicated by pneumonia, hepatitis, and endocarditis
S/S: abrupt onset of fever, chills, head and muscle ache, and sometimes rash
NHFD: Cat Scratch Disease
Causative Organism: Bartonella henselae (G-)
Trans: parenteral (cat scratch or bite)
V Factors: endotoxin
Culture/dx: biopsy of lymph nodes + gram staining; ELISA performed by CDC
Prevention: Clean wound sites, control fleas
Tx: Azithromycin
D Feats: history of cat bite or scratch; fever not always present
Epi Feats:
NHFD: Ehrlichiosis
Causative Organism: Ehrlichia species (G-)
Trans: bio vector (tick- Ixodes species)
V Factors: —
Culture/dx: PCR, indirect antibody test
Prevention: avoid ticks
Tx: Doxycycline
S/S: acute febrile state resulting in headache, muscle pain, and rigors
D Feats: Southeast, South central US
Epi Feats:
NHFD: Anaplasmosis
Causative Organism: Anaplasma species (G-)
Trans: biological vector (tick)
V Factors: —
Culture/dx: PCR, indirect antibody
Prevention: avoid ticks
Tx: Doxycycline
D Feats: Upper Midwest and northeastern US
Epi Feats: increase in incidence since mid 1990’s; similar to Ehrlichia but different in geographic distribution
NHFD: Babesiosis
Causative Organism: PROTOZOA: Babesia species
Trans: bio vector (tick)
V Factors: —
Culture/dx: blood smear (protozoa seen in blood smear as they infect RBCs)
Prevention: avoid ticks
Tx: combo of therapy with antibacterial and antiprotozoal
D Feats: Northeastern and upper midwestern US; protozoan that infects red blood cells
Epi Feats:
NHFD: Spotted Fever Rickettsiosis
Causative Organism: Rickettsia species (G-)
Trans: biological vector (tick - wood tick, American dog tick, Lone star tick)
V Factors: induces apoptosis in cells lining blood vessels
Culture/dx: Fluorescent antibody, PCR
Prevention: avoid ticks
Tx: Doxycycline
S/S: after 2-4 days of inc., the first sx are: sustained fever, chills, headache, and muscular pain; cardiovascular disruption like hypotension, thrombosis, and hemorrhage
D Feats: Rocky Mountain Spotted Fever is most severe of Rickettsioses; untreated lesions can become necrotic
—> early lesions of Rocky Mountain Spotted Fever may resemble the rash of MEASLES, on wrists, forearms, and ankles before spreading
Epi Feats: Tenfold increase since 2000
Chagas Disease
“American trypanosomiasis, new AIDS of the Americas”
Causative Org: flagellated protozoan Trypanosoma cruzi
Trans: biological vector (Triatomine bug), vertical
V Factors: antioxidant enzymes, co-opting host antigens; induces autoimmunity
Culture/dx: blood smear in acute phase; serological testing in later phases
Prevention: insect control; no vaccine
Tx: consult CDC; most successful if it begins during acute phase
S/S: acute phase: mild-severe fever, nausea, fatigue, Chagoma swelling may be present at site of bug bite and if by eyes Romana’s sign may appear;
-acute phase pasts for weeks or months and then becomes chronic which is virtually asymptomatic for a period of years or indefinitely
D Feats: —
Epi Feats: endemic in central and south America; 300,000 cases present in US; one of five NEGLECTED PARASITIC DISEASES
Anthrax
causes disease in the lungs and in the skin, we address Anthrax in this section because it multiplies in large numbers in the blood and because SEPTICEMIC ANTHRAC is a possible outcome of all forms of anthrax
-zoonotic disease, Robert Koch used anthrax as a model for developing postulates in 1877, and later, Louis Pasteur used the disease to prove the usefulness of the vaccine
Anthrax info
Causative Org: Bacillus anthracis (G+) (endospore forming)
Trans: vehicle (air, soil), indirect contact (animal hides), vehicle (food)
V Factors: Triple exotoxin (tripartite - protein complex composed of three separate exotoxins = massive inflamm. and shock)
Culture/dx: Culture on blood agar, direct fluorescent antibody tests
Prevention: vaccine for high risk population
Tx: in consult with CDC
S/S: in the lungs (pulmonary anthrax), on the skin (cutaneous anthrax), gastro tract (acquired through ingestion of contaminated foods)
—> septicemic anthrax also results in headache, malaise, fever, and bleeding in the intestine and from mucous membranes and orifices may occur in later stages
D Feats:
Epi Feats: internationally, 2000-20,000 cases annually, most cutaneous; CATEGORY A BIOTERROISM AGENT
Which of the following have evolved an intracellular lifestyle?
a. Bacillus anthracis -> anthrax
b. Coxiella burnetii -> Q Fever
c. MRSA
d. Two of these
b.
—> anthrax V factor is triple exotoxin
which of the following is a G+ bacteria?
a. S. aureus
b. Borrelia burgdorferi
c. Coxiella burnetti -> NHFD
d. Trypanosoma cruzi
a.
—>c. is NHFD, and they were all G-
—> b. is lyme disease and is G-
—>d. is a protozoa
which of the following diseases is characterized by the formation of a biofilm?
a. plague
b. HIV
c. endocarditis
d. Chagas disease
c. (biofilms can accumulate, especially in congenital forms because bacteria are drawn to abnormal heart valves)
d. is bug bite
a. is flea bite
c. is intro of virus
which of the following diseases is caused by retrovirus?
a. Lassa virus
b. Ebola
c. Anthrax
d. HIV
d. HIV
- ->a. and b. are hemorrhagic fever
- –> anthrax is not retrovirus, and is caused by BACTERIA endospores
the bite of a tick can cause
a. ehrlichiosis
b. lyme disease
c. anaplasmosis
d. all of these
d.
—> a and c and NHFD
normal biota in the oral cavity are most likely to cause
a. acute endocarditis
b. subacute endocarditis
c. malaria
d. tularemia
b. subacute endo
—>c. is a virus
