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Infectious Disease
midterm review
Question | Answer |
---|---|
Study of the distribution & determinants of disease frequency in populations | epidemiology |
What is relative risk? | increased rate in exposed/increased rate in nonexposed; done in cohort studies |
What is an odds-ratio? | Estimate what the relative risk would be if cohorts were done. Used in case-control studies |
What are sources of error in epidemiology studies? | confounding & bias |
Ability of a test to identify all screened individuals who actuall has the disease | sensitivity |
Ability of a test to identify nondiseased individuals who do not have the disease | specificity |
Can both the sensitivity and specifity be 100%? | No |
Which test has few false negatives? | sensitivity test |
Which test has few false positives? | specificity test |
Study in which the population group that is followed over time is evaluated for exposure of interest and over time are monitered for the disease of interest | cohort studies |
Study in which compares 2 groups at a time and both groups are than evaluated for the exposure | case-control studies |
Compare direct and indirect transmission. | direct is person to person and indirect uses a vector |
Explain why HIV has such a high rate of mutation. | reverse transcriptase is very prone to erro and can't proofread |
What are some of the infections that HIV positive individuals are at higher risk for? | TB, salmonella, HSV-1, cytomegalovirus, candidiasis, toxoplasmosis, fungal lung infections that disseminate |
What are the 3 stages of an HIV infection? | Acute, Latency, AIDS |
Describe the acute stage of an HIV infection | flu-like symptoms, occurs after several weeks, increases virus in blood, circulating antibodies appear. |
Describe the latency stage of an HIV infection | asymptomatic, they are in this stage as long as the immune system is functional, decrease in the virus, decrease in CD4 cells, opportunistic infections is possible and it last approx. 10 years. |
Describe the AIDS stage of and HIV infection | CD4 decreases below 200/ml, malignancies associated with AIDS occur(kaposi, lymphoma's), lead to dementia, increase chance of opportunistic infections |
What are the ways the HIV virus is transmitted? | sex, contaminated needles, transfusions, perinatal transmission including breast milk |
What is the function of reverse transcriptase? | viral RNA to DNA |
What is the function of integrase? | cleaves host DNA and inserts viral DNA into it |
What is the function of protease? | cleaves polyprotein into proteins which than assemble into mature virus |
While many fungal infections are acquired by spore inhalation, what are some that are spread person-to-person? | tinea pedis - athletes foot; tinea corporis - ringworm; tinea capitus - scalp ringworm |
What are the 2 types of leprosy? | tuberculoid, lepromatous |
Describe tuberculoid leprosy | host increases resistant, macular lesions in cooler body tissues such as nose and outer ear |
Describe lepromatous leprosy | lack's resistance, extensive skin destuction, nodues |
Most commmon fom of leprosy? | mixture of tuberculoid and lepromatous |
What two bacteria that cause skin lesions are considered animal pathogens? | bacillus anthracis(cutneous anthrax) & francisella tularesis(tularemia) |
What are the 3 forms of leishmaniasis? | cutaneous, mucocutaneous, visceral |
Describe cutaneous leishmaniasis | skin sores that leave scars |
Describe mucocutaneous leishmaniasis | multiple lesions, parasite attacks mucosal-dermal junctions of nose and mouth and can destroy the nasal septum |
Describe visceral leishmaniasis | in spleen, liver and bone marrow |
What cells do the Leishmania parasites invade? | macrophages |
Chronic infectio with this tissue nematode can lead to elephantiasis? | wuchereria bancrofti & brugia malayi |
Causative agent, vector and the symptoms of Rocky Mountain spotted fever | wood tick, rash on limbs first occurs |
Causative agent, vector and the symptoms of epidemic typhus fever | rickettsia prowazcki, body louse, rash on trunk than limbs with increased fever |
Causative agent, vector and the symptoms of endemic typhus fever | rickettsia typhi, rat flea, rash on chest and abs. |
Brill-Zinsser disease is a recurrence of what disease? | Epidemic Typhus Fever? |
What 3 diseases/infectious agents are transmitted by the deer tick? | Lymes disease, anaplasmosis, babesiosis |
Causative agent of anaplasmosis | anaplasma phagocytophilum |
Causative agent of ehrlichiosis | ehrlichia chaffeensis |
Vector of anaplasmosis | deer tick |
Vector of ehrlichiosis | lone star tick |
Geographical location of ehrlichiosis | southeast US |
Cells infected by anaplasmosis | neutrophils |
Cells infected by ehrlichiosis | monocytes |
What filarial worm can cause blindness? | onchecerea volvulus |
What cells do the babesia parasites infect? | RBC? |
Name the organism that is the most common cause of bone infections? | Staph aureus |
Name the organism that is the most common cause of septic arthritis? | Staph aureus |
Individuals that work with plants such as farmers or gardeners are at risk for what subcutaneous fungal infection? | sporotrichosis |
Someone who has shingles has had what viral infection in the past? | chicken pox |
Kiplik spots are considered diagnostic for what infection? | Measles AKA Rubeola |
Why is it dangerous for a pregnant woman to contract rubella AKD German Measles? | miscarriage, stillbirth, congenital defects |
What is Reye's syndrome? | Syndrome that follows a viral infection; Sx include rash, vomiting, acute encephalopathy, lilver malfunction.... |
What medication may be associated with Reye's syndrome? | aspirin in children |
Which virus causes the "slapped check" rash? | parovirus B19 |
Discuss some barriers in the GI tract to infectious agents? | unbroken epithelium covering all parts, epithelial cell surface structures, mucous, aciditiy of stomach, bile, normal flora |
What is an infection in the GI tract? | Infection is when ingesting food contaminated, the bacteria will grow into the GI and cause symptoms. often times producing toxins. |
What is an intoxication in the GI tract? | Intoxication is when bacteria grow in food and produces a toxin. When ingested this causes the symptoms. |
Examples of infecious agents that cause an intoxication in the GI tract? | staph aureus, bacillus cereus, clostridium perfrinigens, clostridium botulinum |
What age group is most likely to have a rotavirus infection? | infants and young children |
What is infant botulism? | floppy baby syndrome and they have neurological symptoms |
Name 2 protozoans that cause a non-inflammatory gastroenteritis? | giardia lamblia and cryptosporidium parvum |
Long term broad-spectrum use of antibiotics puts a patient at risk for infection with what bacteria? | clostridium difficule |
What 2 diseases do species of Salmonella cause? | gastroenteritis(food poisening) & typhoid fever(enteric fever) |
How would u diagnose ascaris? | finding eggs in a stool sample |
How would u diagnose necator? | finding eggs in a stool sample |
How would u diagnose strongyloides? | finding larvae in a stool sample |
How would u diagnose trichuris? | finding eggs in a stoold sample |
How would u diagnose enterobius? | scotch tape test |
What is the intermediate host for Taenia saginata? | beef tapeworm |
What is the intermediate host for Taenia solium? | pork tapeworm |
What is the intermediate host for Diphyllobothrium latum? | fish tapeworm |
With which of the tapeworms can a man be an accidental intermediate host? | pork tapeworm |
Which tapeworm competes with the host for vitamin B12? | fish tapeworm |
In which nematodes does the larval stage migrate through the lungs before becoming adults in the intestines? | Ascaris lumbricoides, Necatar americanus, Strongyoides sterocoralis, Ancylostoma duodenale |
Which intestinal nematode infection can have an auto-infection because the worm eggs hatch in the intestine? | strongyloides stercoralis |
What parasite causes amebic dysentery? | Entamoeba histolytica |
Trematode parasites have what organism as an intermediate host? | snail and water plants |
Which hepatitis viruses are considered fecal-borne? | A & E |
Which hepatitis viruses are considered blood-borne? | B, C & D |
What are the signs/symptoms for all acute viral hepatitis infections? | ferver, fatigue, nausea, loss of appetite, jaundice, dark urine & clay-colored stools, increased liver enzymes and hepatomegaly |
What is unique about hepatits D? | requires the presence of HBV for transmission |
Which hepatitis infections can progress to a chronic infection? | Hep B and Hep C |
How is yellow fever transmitted? | mosquitos |
How is an infection with Schistosoma acquired? | direct skin penetration |
How is an infection with Schistosoma diagnosed? | eggs in stool or urine sample |
What are 2 liver flukes or trematodes | Clonorchis sinensis & Fasicula hepatica |
What are the intermediate hosts for the liver flukes? | snail & fish |
What are the signs & sx of acute bacterial meningitis? | fever/chills, HA, malaise, stiff neck, vomiting, eye problems, petechia, myalgia, drowsiness, impaired mental development & hearing loss in kids |
What free-living amoeba causes an acute, often-fatal meningoencephalitis? | Naegleria fowleri |
What 3 groups of viruses can cause viral meningitis or viral encephalitis? | enterovirus, arbovirus, herpes simplex |
Infectious agents likely for bacterial meningitis from newborns to 3 months? | E Coli, Group B Strep, Listeria monocytogens |
Infectious agents likely for bacterial meningitis from 3 months to 6 months? | Haemophilus influenzae, Neisseria meningitides, Streptococcus pneumoniae |
Infectious agents likely for bacterial meningitis from over 6 months of age to adults? | Streptococcus pneumoniae & Neisseria mengitides |
What are the 3 clinical forms of polio? | absorptive, asceptic/non-paralytic, paralytic |
Describe absorptive polio | most common, asymptomatic or fever, HA, malaise, sore throat, nausea, vomiting, rapid recovery, illness is mild and usually not diagnosed |
Describe aseptic/non-paralytic polio | enters CNS, sx of absorptive polio plus stiff neck and back, 1 week recovery |
Describe paralytic polio | extension of aseptic polio, destroys large motor neurons in anterior horn causing paralysis, may affect neurons in medulla & brainstem affecting respiratory or vasomotor center, most cases recover in 6-24 months |
What is post polio syndrome? | unexpected fatigue/px/weakness, happens 30-40 years later but can occur in any paralytic polio case even with full recovery, virus is not involved |
How does the rabies virus reach the CNS? | bite site through PNS |
When a lab does an India ink prep of spinal fluid, what are they looking for? | cryptococcus neoformans yeast with capsules |
What is the mechanism of tetanus toxin? | Affects CNS and blooks the release of inhibiting NTX resulting in excitation of motor neurons, spasmatic contractions occur |
What is the mechanism of botulism toxin? | Inhibition of ACh preventing contraction causing flaccid paralysis |
What are the 3 different botulism infections? | classic, infant & wound |
Describe classic botulism | caused by food poisening by ingesting toxins already in food |
Describe infant botulism | ingest spores that grow as bacteria in the intestine than produce toxins in the GI |
Describe wound botulism | grow in wound and produce toxins |
What are the S/S of CJD? | loss of motor control, dementia, paralysis wasting & death |
What are the 3 variations of CJD? | classic, variant, genetic |
Describe classic CJD? | sporadic; median death age is 68 |
Describe variant CJD? | bovine spongiform encephalopathy (cattle disease), 28 years is median age of death |
Describe genetic CJD? | inherit a mutated PP gene |