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Micro final exam 2


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spread of Mumps
-by airborne droplets, salivary secretions and possibly urine
Where does Mumps virus spread to after enters resp tract?
-spreads systemically to lymphoid tissues,
-7-10 days later, enters blood and localizes in salivary and other glands
mumps incubation period
-18-21 days
signs of mumps
-parotid gland is painful, tender and swollen
-present in 30-40% of cases
tx of mumps
-no specific treatment, but live attenuated vaccine (MMR)
-pt has life-long resistance to reinfection
Reubella (german measles)
-droplet infection
-less contagious than measles
-14-21 days there is mild disease with fever, malaise, maculopapular rash lasting 3 days
rubella tx
-live attenuated vaccine (MMR)
-larges human herpesvirus; one serotype
CMV transmission
-saliva and originally known as salivary gland viruses
-urine, semen and cervical secretions may also contain and be spread by sexual contact
-hospitals - by blood transfusions and organ transplant
CMV spreads to:
-spreads to lymphoid tissues and then systemically in circulating monocytes and lymphocytes
-localizes in epithelial cells of salivary glands and kidney tubules and in cervix, epididymis and testes
-infection usually asymptomatic
CMV may cause:
1. fetal malformations - small head, small size, MR, hearing loss, jaundice
2. interstitial pneumonia - in immunodeficient patients
CMV tx:
-no vaccine
EBV infection transmission
-transmitted by exchange of saliva (during kissing)
-replicates in B lymphocytes binding to C3d receptor on these cells
-disease attributed to immunologic response
-symptoms due to action of cytokines released
EBV signs
-no clinical disease in infants or small children
-older children and young adults: infectious mono, fever, sore throat, petechiae on hard palate, lymphadenopathy, splenomegaly, anorexia, and lethargy
Triad of EBV
-sore throat with pus, lymphadenopathy, splenomegaly
EBV tx:
- no reliable antiviral agen, no vaccine
-EBV remains latent in small proportion of B cells
Burkitt's lymphoma restricted to what areas:
-Africa and Papua New Guinea
Burkitt's lymphoma
-EBV closely associated with this, but not enough to cause lymphoma;
-carcinogen is malaria which acts by weakening T cell control of EBV infection
Small pox cause
-caused by poxvirus and spread from person to person by contact with skin lesions and via resp tract
Smallpox eradication
-officially certified in 1980 by widespread vaccination using attenuated strain of virus (vaccinia = cowpox)
global eradication of smallpox was possible:
1. no subclinical infections
2. no carriers
3. no animal reservoir (only humans infected)
4. an effective vaccine was available
Arbovirus infections
-arthropod borne viruses
-transmitted by ticks, mosquitoes, sandflies
-virus enters when arthropod takes a bloodmeal, and multiplies in salivary gland
Arbovirus infections
1. yellow fever
2. dengue fever
yellow fever
-restricted to Africa, Central and S. America, Caribbean
-transmitted from person to person by mosquitoe (Aedes aegypti)
-transmitted from monkeys to humans by mosquitoes (Haemagogus); jungle yellow fever
-sx: fever, HA, muscular aches, shock, severe liver damage, death
-tx: live attenuated vacc; insecticides on vector; insect repellent
Dengue fever
-in SE Asia, Pacific, India, Carribean
-human vector: mosquito (A. aegypti)
-sx: malaise, fever, nausea, vomiting, maculopapular rash, dengue hemorrhagic fever syndrome
-increased monocytes leads to increased release of cytokines - causing shock, hemorrhage
-tx: none
Rickettsial infection
-small bacteria that are obligatge parasites
-transmitted by arthropods (tick & lice)
-sx: fever, HA, rash
Rickettsial infections (4)
1. rocky mountain spotted fever
2. mediterranean spotted fever
3. epidemic typhus
4. endemic typhus
Rocky mountain spotted fever
-occurs Rocky mtn states and eastern US
-caused by R. rickettsii
-carried by dog tick and wood ticks
-sx: fever, HA, maculopapular rash, splenomegaly, neurologic involvement, shock, death
mediterranean spotted fever
-in mediterranean
-caused by R. conorri
-carried by dog ticks
-50% develop fever, HA, rash in palms and soles
Epidemic typhus
-in Africa & S America
-caused by R. prowazeckii
-transmitted person 2 person by louse (pediculus corporis)
-assoc with poverty and war
-fever, HA, flu-like sx, rash, sometimes severe meningoencephalitis with delirium and coma
Endemic typhus
-caused by R. typhi
-transmitted by rat flea
-same as epidemic typhus but less severe
Lyme disease
-caused by borrelia and transmitted by hard ticks of Ixodes genus
-cycle of infection occurs in mice and deer
-occurs in Europe, USA, most continents
-fever, HA, lymphadenopathy, erythema chronicum migrans - lesion at site of bite - center clears
-causes additional diseases: neurologic, cardiologic, arthraglia, arthritis
-tx: antibiotics like penicillin and tetracycline
(species, where it occurs, transmitted)
-Plasmodium falciparum most virulent
-initiated by bite of female anopheles mosquito
-Africa, India, far East and S America
-can be transmitted by blood transfusions and needle accidents
Life cycle of malaria parasite:
-sporozoites from saliva of mosquito enter blood stream
-in liver, mature into merozoites (some stay and lie dormant called hypnozoites)
-merozoites enter RBC, multiply, and get released into bloodstream
-some merozoites initiate sexual stage by forming male & female gamaetocytes
-sexual cycle complete when mosquito feeds on gametocyte containing blood
-forms a zygote that gives rise to sporozoites that initiate cycle again
Why is there a 48 or 72hr periodicity of fever in malaria?
-b/c of synchronous cycle times
Malaria sx & tx:
-fever (starts with intense cold and shivering followed by hot dry stage, followed by drenching sweat)
-HA, vomiting, muscle spasms
-fatal during first 2-3 wks due to complications
-cerebral malaria, severe anemia, hypoglycemia and lactic acidosis
-has immunosuppressive effect
-tx: chloroquinine, mosquito repellents
Trypanosomiasis (2)
1. African trypanosomiasis
2. Chaga's disease
African trypanosomiasis:
(cause, vector, reservoir, sx, tx)
-caused by T. brucei gambiense and T. rhodesiense
-vector: tse-tse fly
-reservoir is domestic and wild animals
-chancre develops as site of bite with lymph node enlargment, fever, splenomegaly, HA, psy changes, voracious appetite, wt loss, coma (sleeping sickness)
-tx: arsenical drugs, non-arsenical drugs
-t. brucei can survive by antigenic variation
Chaga's disease:
(cause, transmission, sx, cause of death tx)
-caused by T.cruzi
-transmitted by reduviid bug (kissing bug) - cause of S Am trypanosomiasis
-sx: involve heart and intestinal tract
-cause of death: myocarditis
-tx: one of most difficult protozoal infections to cure
(transmission, what are they, where do they grow?)
-transmitted by sandflies
-are intracellular parasites inhabiting macrophages
-grows in spleen and liver (viscerla leshmaniasis) and in skin (cutaneous leshmaniasis)
visceral leishmaniasis
-develops slowly with fever, wt loss, hepatomegaly, splenomegaly
-untx: die from liver failure
-called Kal-azar
Cutaneous leishmaniasis
-starts as small papule at site of infection and develops into lg ulcer with scarring
2 type of Helminths infections
1. Schistosomiasis
2. Filariasis
- schistosomes penetrate skin
-migrate to lungs & liver where they mature and mate
-egg production leads to pathology of disease
-body becomes hypersensitive to Ags released by eggs: ie - urinary schistosomiasis
-caused by filarial nematodes
Lymphatic filariasis:
-caused by genus Brugia and Wuchereria
-transmitted by mosquitoes
-larvae develop in long worms foundin lymph nodes and lymphatics of limbs & groin
-sx: fever, rashes, chronic obstruction of lymphatics
-leads to gross enlargement of breasts, scrotum, limbs (elephantiasis)
Arenavirus infections
-parasites of rodents that cause harmless life long infection of healthy infected animals
-humans develop severe 2 lethal diseases
Lassa fever virus
-an arenavirus that infects bush rats
-exposure to infected rats or their urine causes febrile disease - not severe
-commonest febrile illness in hospitals in Sierra Leone
-viral transfer to nurse/dr via blood or tissue fluids - causes more severe form
Korean Hemorrhagic fever
-Hantaan virus = a bunyavirus causes harmless persistent inf in mice & rats
-exposure to urine of infected animals - febrile illness with hypotension, hemorrhage, renal syndrome
-causes pulm disease
Marburg & Ebola Hemorrhagic fever
-occur in Central & E. Africa
-caused by filoviruses
-develop fever, hemorrhage, rash, DIC
-reservoir & natural cycle is unknown
Q fever (Query) fever
-caused by rickettsia called Coxiella burnetii
-infection if contact placenta, unpasteurized milk, or tissue fluids of infected livestock
-sx: fever, HA, atypical pneumonia, hepatitis
-recovery in 2 wks
-can become chronic
Coxiella burnetii differes from rickettsia in 3 ways:
1. not transmitted by arthropods
2. transmission by inhalation
3. main action is the lungs
-caused by Bacillus anthracis
-forms spores
-mainly disease of herbivores
-confined to developing countries
-Ags available for animal handlers and military
-vacc for animals
Cutaneous anthrax
-anthrax toxin - edema factor
-papule ulcerates and center becomes black and necrotic = eschar
Pulmonary anthrax
-spores are inhaled
-sx: pulm edema, hemorrhage, spread to blood, death; lethal toxin released

-caused by Yersinia pestis
-reservoirs: rodents
-rat flea carries infection from rats to humans
-signs: lymph nodes in armpits and groin very tender and enlarge to form buboes with hemorrhagic inflammation
-black death = multisystem involvement
bubonic plague
-infected flea bites human
Pneumonic plague
-infection spreads from person to person by droplets
Plague prevented by:
1. quarantine
2. rodent control
3. chemoprophylaxis when visiting infected area
-caused by franchisella tularensis
-present in rodents
-spread by arthropod vectors
-inf occur by contact with infected animal or with arthropod vector (no person 2 person)
-febrile illness & lymphatic spread - swollen painful lymph nodes
-leptospira are tightly coiled spirochtes that infect rats that excrete bacteria in urine
-inf by ingestion of contaminated food or water; can be acquired by swimming
-causes febrile influenza like illness - 90% resolve with no complications
-caused by brucellae (gram neg), infect domestic animals
-bacteria present in feces, urine, milk of animals
-inf occurs when bacteria enter via abrasions in skin
sx: fever, drenching sweats, aching and weakness, enlarged lymh nodes and spleen
-chronic stage (1yr) can develop with tiredness, aches, pains, anxiety, depression
helminth infections (2)
1. Echinococcus
2. Trichinella
-adult tapeworm lives in dog; eggs in fecal material and hatch in human sm intestine
-larvae lodge in liver (mostly) but other places as well
-larvae grow into lg thick walled fluid filled (hydatid) cysts
-pt show marked abdominal swelling caused by hydatid cysts
-caused by T. spiralis (nematode)
-infected after eating undercooked meat (pork or wild animal)
-larvae mature only in striated muscle whey they form cysts
-fever, jt & muscle pain, hemorrhage, encephalitis, cardiac abnormalities
haemophilus meningitis
-caused by Haemophilus influenzae
-causes meningitis in infants from 3months to 3 yrs
-incubation period is 5-6days and condition is less frequently fatal but 105 higher incidence of lasting complications like hearing loss, delayed language dev, MR and seizures
-vaccine for 6 months
Pneumococcal meningitis
-caused by Streptococcus pneumoniae
-carried in throats of many healthy individuals
-more common in children < 2 yrs and in elderly
Listeria monocytogenes meningitis
-imp cause of meningitis in immunocompromised adults, especially renal transplants and CA
Neonatal meningitis
-caused by E. coli and group B hemolytic streptococci
-fatal in 35%; leads to nerve palsy, epilepsy, MR, hydrocephalus
-dx in neonate very difficult with sx: fever, poor feeding, vomiting, resp distress, diarrhea
tub erculous meningitis
-assoc with acute miliary TB
-sx: malaise, apathy, anorexia, photophobia, neck stiffness, impairment of consciousness
fungal meningitis
-Cryptococcus neoformans and Coccidioides immitis invade blood from inf in lungs and then infect brain
-c. neoformans meningitis in depressed cell mediated immunity pts
-C. immitis meningitis in SW US, mexico, S America
Protozoan meningitis
-free living amoeba - naegleria and Hartmanella
-multiply in stagnant water
-inhaled/swallowed- reach meninges via the olfactory tract and cause meningitis
-high mortality
Viral meningitis
-commonest type
-milder disease than bacterial
-HA, fever, general illness, stiff neck
-many viruses can cause meningitis
-no antiviral drugs, complete recovery is the rule
-caused by viruses
-abnormal behavior, seizures, altered consciousness often assoc with N/V, and fever
HSV 1 encephalitis
-commonest severe sporadic encephalitis
-2 forms: 1. primary and general inf in infancy
2. in adults and due to reactivation in trigeminal ganglia
-tx: acyclovir
-used to be common cause of encephalitis
-fever, sore throat, malaise, meningeal signs and sx, paralysis
-prevented by vaccination
-common cause of mild encephalitis
Rabies encephalitis
-caused by rabies virus
-in infected dogs, foxes, jackals, wolves, skunks, raccoons, vampire bats
-transmission follows a bite or salivary contamination
-virus travels up peripheral nerves
-durther the bite from the CNS the longer the incubation period
-virus invades the limbic system
-sx: sore throat, HA, fever, discomfort at bite site, muscle spasms, convulsions, hydrophobia
4 preventive actions if biten by infected animal (Rabies)
1. prompt cleaning of wound
2. confirm whether animal is infected
3. adm human raies immunoglobulins
4. active immunization with killed rabies virus
Togavirus meningitis and encephalitis
-caused by arthropod born togaviruses
-western equine encephalomyelitis virus and St. Louis encephalitis virus transmitted by mosquito
-West Nile encep virus - Culex spp.
-Japanese encep virus in India, mortality > 50%; vacc available
Brain abscesses
-rare since Antibiotics
-usually follow surgery or trauma, chronic osteomyelitis, septic embolism
-caused by various bacteria of oropharynx origin
Encephalopathy due to Scrapie-Type agents
(6 features)
1. replicate extremely slow
2. not virus, bacteria, DNA
3. prion protein is altered in infected brain - replication by conversion of host prion prot into abnorm form
4. resistance to heat, chemical agents, irradiation
5. spongiform appearance with no inflammatory response
6. no tx or vacc, disease is lethal
Creutzfeldt-Jakob Disease (CJD)
-from eating bovine spongiform encephalopathy (BSE) contaminated food
-transmitted person to person by: corneal grafts, inj of growth horm, electrodes not completely sterilized
-10% occurs in families
-fatal neurologic disease
-in Fore tribes in Papua New Guinea
-transmission: person to person
-caused by Clostridium tetani
-spores ar widespread in soil and animal feces
-spores enter wound and if tissue is necrotized it allows growth
-toxin blocks the release of inhibitory mediators in synapses causing overactivity of motor neurons leading to spastic paralysis
-exaggerated reflexes, muscle rigidity, uncontrolled musc spasms, lockjaw, dysphagia
-mortality 50%
-vaccine - toxoid
-spores widespread in soil and contaminate vegs, meat, fish
-spores can survive in improperly canned foods
-toxin blocks release of Ach
-descending weakness, flaccid paralysis with dysphagia, vomiting, vertigo, resp failure
Staphylococcal skin infections
-S. aureus most common
-causes boils, abscesses and postop wound infections
-acquired by self-inoculation or person to person
-begins as superficial infection around a hair follicle
-s. aureus most common cause
-contains abundant yellow creamy pus formed by organisms and dead WBC
Staphylococcal scalded skin syndrome
-in infants and older children
-caused by toxin producing S. aureus
-toxin known as exfoliatin or scalded sking syndrome toxin
-toxin causes separation btw epidermis and dermis
-lg blisters, within 1-2 days skin lost
Toxic Shock Syndrome
-caused by toxic shock syndrome toxin producing Staph aureus
-came to be with super absorbent tampon use in healthy women
-can occur at non-genital sites
-toxemia, rash, deaquamation of skin on soles and palms
Streptococcal skin infections
-caused by Strep. pyogenes
-strepococcal impetigo - limited to epidermis - crusted, yellow papules
-strep. pyogenes - infect deeper causing erysipelas - involves blocking of dermal lymphatics, erythromatous inflammation generlaly on face, legs, or feet, fever, pain
strep infection in the subq fat
-hot red swollen lesion, regional lymph nodes are enlarged, malaise, chills, fever
-caused by strep pyogenes and staph aureus
anaerobic cellulitis
-assoc with surgical ro traumatic wounds
-diabetics more prone
-foul-smelling discharge, marked swelling and gas in tissues
necrotizing fascitis
-flesh eating bacteria
-resembles bacterial gangrene but more acute and highly toxic infection
-causes widespread necrosis
-pt deteriortes rapidly and dies
Clostridium infections
-Clostridium perfringens causes gas gangrene
-develops where circulation is poor
-causes necrosis and produce gas bubbles
-damage due to lecithinase (alpha toxin)
-toxin hydrolyzes the lipids in cell membrane resulting in cell lysis and death
-toxin in blood - massive hemolysis - death
propionibacterium acnes
-increase in androgenic hormones leads to increase sebum production
-black heads (comedones)
-caused by Mycobacterium leprae
-not highly contagious
-organism grows at temp below 37 C
-grows in macrophages and schwann cells of peripheral nerves
Leprosy (2 forms)
name 1
1. Tuberculoid Leprosy (TT) - blotchy red lesions, anesthetic areas of face, trunk, exgtremities
-good prognosis
Leprosy - name other form
-Lepromatous Leprosy (LL) - extensive skin involvement, loss of eyebrows, thickening of nostrils, ears and cheeks, typical lion like appearance
-superficial mycoses - the most common infections in humans
-keratin loving and invade skin, hair, and nails
-tinea capitis, tinea corporis, tinea pedis
-main sx: thickening, skin dry and scaly
Papillomavirus infection
-skin papillomas or warts
-5 types that infect genital areas - genital warts have cauliflower like appearance
-HPV 1 and 4 - plantar warts - flat, acquire from contaminated floors, spread by shaving
HPV 2,3,10- common warts on hands
-enters by surface abrasions, infects basal layers of skin
-months after infection - wart regresses and DNA remains latent in basal layer
Herples simplex virus infection
-HSV 1 in childhood
-transmitted from saliva or cold sores
-virus rich vesicles ulcerate
-virus enters sensory nerves and initiate latent infection in trigeminal ganglia
-virus remains for life
-can reactivate and move down sensory n to cause cold sores
Primary infections can occur in:
1. eye to cause conjuctivitis
2. finger
3. other skin sites
4. genital tract
Reactivation provoked by:
1. common cold, pneumonia, fever
2. direct sunlight
3. stress
4. menstruation
5. immnunocompromise
VZV infection
-VZV causes ckn pox (varicella) and zoster (shingles)
-highly contagious
-part of herpesvirus group
-inhalation, saliva, or direct contact
-primary infection causes ckn pox
-virus persists in body - later can cause reactivation of shingles
-after primary infection, virus infects lymphoid tissues, enters blood, moves to epithelial cells of trunk, face, scalp
-vesicles appear as crops, then pustules, then scab over
-complications in adults: interstitial pneum, CNS
-latent infection in dorsal root ganglia
-reactivation leads to erythromaous rash in thoracic region
predispose to zoster:
1. increase age
2. immunocompromise
3. fracturs/tumors
-live attenuated vacc available
Human herpes virus 6 (HHV6)
-infects nearly all humans by frist 5 yrs of life
-roseola infantum (rash)

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