Infection

Question 1

what are parasites?

Answer 1

organisms which are dependent on another for its survival, to the detriment of its hosts survival

Question 2

what are considered parasites?

Answer 2

helminths
insects
protozoa

Question 3

what are endoparasites and what do they include?

Answer 3

parasites that live inside the body

they include helminths and protozoa

Question 4

what are ectoparasites and what do they include?

Answer 4

they live outside the body which include insects such as fleas, lice, bedbugs and ticks

Question 5

give an example of a protozoan endoparasite

Answer 5

entamoeba histolyca
this invades the large bowl lining, causing dysentery - excreted with faeces and spread via contaminated food and water - has a higher risk with poor hygiene

plasmodium falciparium (malaria) 
has a lifecycle in both humans and mosquitoes. it infects red blood cells and liver. gives fever, headache and joint pain and can lead to kidney failure , coma and death

Question 6

what are 3 types of helminths

Answer 6

crestodes

termatodes

nermatodes

Question 7

give an example of a crestode?

Answer 7

tape worms - segemnted and flat
causes abdominal pain and malnutrition.
diagnose by microscopy of the stool for eggs
cattle is intermediate host

Question 8

give an example of trematodes

Answer 8

schistosoma haematobium (bilharzia) - flukes, unsegmented and flat

infection of veins around the bladder, casuing inflammation and bleeding into urine (haematuria)
intermediate host = freshwater snail
diagnose by urine microscopy

Question 9

what are nematodes

Answer 9

round worms that have cylindrical digestive tract with lips, teeth and anus

Question 10

give an example of an ectoparasite

Answer 10

begbugs
cimex lecturlaris
wingless insect, worldwide infestation of human dwellings, they hide in cracks in furniture and walls. they emerge at nigh for blood meal
gives an itchy rash after bite and can transmit other infections

Question 11

what is the mode of transmission of malaria

Answer 11

malaria is transported by mosquito vectors (anopheles spp)

Question 12

what is the mode of transmission of tapeworms

Answer 12

tapeworms (cestodes) use cattle as intermediate hosts - oncospheres hatch and penetrate intestinal wall and circulate to muscles where they develop into cysticerci. when humans ingest raw or uncooked meat they contract the disease

Question 13

what is the mode of trasnmission of schistosoma?

Answer 13

schistosoma haematobium (bilharzia) is a trematode 
it uses fresh water snails as intermediate hosts. 
first the intermediate host is infected, the cercariae leave the snail and penetrate the skin of the human who is in the water and enters the blood stream (immature worms). 
the worms reach sexual maturity in the veins of abdominal cavity and females lay eggs which enter intestinal tract/ bladdder and passed by urine into fresh water

Question 14

what are some common fungal infections and their cause

Answer 14

tinea pedis (athletes foot) cuased by superficial fungal infection

tinea corporis (ringworm)
caused by superficial fungal infection)

crytococcus neorformans (yeast) - infects patients with failing immune system (HIV) casuing meningitis (inflammation of membranes lining the brain), headache, neck stiffness, confusion, coma and death - sever invasive fungal infection

Question 15

describe the basic classifation of bacteria

Answer 15

shape - round=coccus, rod=bacillus

grouping - clusters, chains or pairs

Question 16

what is a virus?

Answer 16

dependent on infection of a host cell for metabolism and replication
they contain a protein core surrounding genetic material (DNA or RNA), protein coat and sometimes outer membrane.
can only be seen with powerful electron microscope

Question 17

what virus causes the common cold?

Answer 17

rhinovirus

Question 18

what virus causes winter vomiting disease?

Answer 18

norovirus

Question 19

what virus causes chicken pox?

Answer 19

varicella zoster virus (primary infection)

Question 20

what virus causes shingles?

Answer 20

varicella zoster virus (from dormant chickenpox virus in densory nerve root which reactivates years later)

Question 21

what virus causes glandular fever

Answer 21

epstein barr virus

Question 22

what does acute mean?

Answer 22

microbe living inside host for a limited period of time

Question 23

what does chronic mean?

Answer 23

persitant infection that is eventually cleared

Question 24

what does latent mean?

Answer 24

persistant virus which stays until cell dies

Question 25

what are 2 viruses associated with cancer?

Answer 25

``` EBV (epstein barr virus) and HBV (hepatitis B virus) ```

Question 26

why is EBV associated with cancer?

Answer 26

infects immune cells and contributes to certain cancers

Question 27

why is HBV associated with cancer?

Answer 27

it can damage DNA in cells and inflammation of the liver which interferes with how cells behave

Question 28

what are prions?

Answer 28

smallest infective agent k known proteinaceous infectious particle that lack a nucleus and are not living organisms. the proteins are abnormal and accumulate in mainly neural tissue they are very difficult to destroy, standard sterilisation techniques do not work

Question 29

what are 3 diseases that prions cause?

Answer 29

CJD (cretzfeldt-jakob disease) variant CJD - though to be derived from bovine spongiform encephalopathy (BSE or mad cow disease) Kuru - similar to vCJD, spread by cannibalism, especially of brains of deceased relatives

Question 30

what is a endogenous infection?

Answer 30

disease arrising from an infectious agent already present in the body but previously asymptomatic - when normal flora of the gut gets in the wrong place and causes a UTI- cystisis

Question 31

give an example of a endogenous infection

Answer 31

cystisis -infection of the lower urinary tract resulting in : lower abdominal pain, urgency and increased frequency of urinaation, dysuria (painful or difficult urination)

Question 32

what is an exogenous infection?

Answer 32

a disease caused by a pathogen entering the body from the environment

Question 33

host factors preventing disease

Answer 33

``` stomach acid native bacteria immune system genetics - inherited immunodeficieny behaviour ```

Question 34

environmental factors affecting infection

Answer 34

``` geography climate poverty public health infrastructure distribution ```

Question 35

barriers to infection:

Answer 35

skin and mucous membrane | -cuts and abrasions are bad

Question 36

principles of diagnosis

Answer 36

take their history: - non-specific symptoms (fever, loss of apetite, weight gain/loss, muscle ache (myalgia), joint ache (arthralgia) - specific symptoms - according to source - past medical history that would make more susceptible to diseasse - lifestyle activites

Question 37

what are some basic tests used to identify infectious agents

Answer 37

C-reactive protein (CRP) is a marker for inflammation U&E -urea and electrolyte levels (kidney function indicator) LFT - liver function tests antigen testing - for pneumonia and hepatitis B antibody testing culture antibiotic sensitivity testing PCR microsocopy

Question 38

what are desired characteristic of antimicrobial agents?

Answer 38

selective toxicity bacteriocidal(kills instead of inhibiting growth - bracteriostaitc) no resistance good pharmacokinetics(reach high level int he body and stay there allowing a few doses per day) no side effects not affected by enzymes secreted by microbes or by the host.

Question 39

what are some problems with antimicrobials?

Answer 39

variable spectrum of activity - borad spectrum = kill lots of different organisms, narrow =v kills few organisms cannot be given orally many cause side effects which can be serious e.g. anaphylaxis bacterial resistance

Question 40

how would you prevent spread of a airborne infection

Answer 40

isolate infected patient in negative pressure room (filters out going air)

Question 41

how would you prevent spread of a food/water borne infection

Answer 41

sanitation, clean water supplies, food preparation hygiene

Question 42

how would you prevent spread of a contact infection

Answer 42

handwashing | wearing gloves, gown, mask

Question 43

how would you prevent spread of a vector borne infection

Answer 43

avoid mosquito bites, insect repellant, bed nets, long sleeves

Question 44

which organism causes dysentery?

Answer 44

entamoeba histolytica

Question 45

which insect transmits plasmodium falciparum to humans?

Answer 45

mosquitoes

Question 46

what type of parasitic worms are unsegmented and flat, give an example

Answer 46

trematodes (flukes) | schistosoma haemtobium

Question 47

what is the intermediate host for the tapeworm taenia solium

Answer 47

pig

Question 48

what sort of organism causes atheltes foot?

Answer 48

fungus

Question 49

what is the basic structure of a virus

Answer 49

protein coat surrounding protein core with nucelic acid

Question 50

how does varicella zoster virus cause shingles many years after it causes chicken pox

Answer 50

virus lies dormant in sensory nerve roots for many years

Question 51

name 3 human disease caused by prions

Answer 51

Kuru Creuztfeld jakob disease vCJD

Question 52

What is cystisis and what is the commonest cause

Answer 52

lower urinary tract infection | caused by infection with gut bacteria such as eschericia coli

Question 53

what symptoms are causued by the norovirus

Answer 53

vomiting and diarrhoea

Question 54

what bacterium cuases tetanus (lock jaw)

Answer 54

clostridium tetani

Question 55

what type of infection is malaria?

Answer 55

parasitic

Question 56

the spread of rubeela from mother to child during pregnancy is what type of transmission?

Answer 56

vertical

Question 57

what is the mechanism by which cholera toxin acts

Answer 57

activates adenyl cyclase increasing cAMP reduces Na+absorption increases Cl- secretion water and other electrolytes are drawn into the bowel lumen = diarrhoea

Question 58

why woulda patient with TB be isolated in a negative pressure room?

Answer 58

disease is spread by airborne trasnmission

Question 59

name 4 impotant diseases for which there is currently no vaccine available

Answer 59

HIV meningococcus gorup B HCV malaria

Question 60

which vaccination protects against cervical cancer

Answer 60

HPV

Question 61

what is taenia seginata?

Answer 61

tape worm

Question 62

what is entamoeba histolytica?

Answer 62

anaerobic parasitic protozoan

Question 63

which zone of lung are you most likely to have collapsed vessels?

Answer 63

zone 1

Question 64

what is most of co2 transported as in the blood?

Answer 64

bicarbonate ions

Question 65

where in the repsiratory centre is the pneumotaxic centre located?

Answer 65

pons

Question 66

what is atelectasis?

Answer 66

airway collapse