Flashcards in Infectious Disease 1 Deck (127):
Particular food implicated in Hep A transmission?
Symptoms of Hep A?
Nausea, vomiting, malaise
Signs of Hep A?
What test is diagnostic of Hep A?
What test can be used to investigate previous HAV infection?
3 preventative measures for Hep A?
Good sanitation in developing countries
Good hygiene practises
How is HBV transmitted?
Blood-borne, sexual/bodily fluids and vertically
Particular RFs for HBV infection?
Sexual contact with infected person
Tattoos, particularly foreign countries
Medical treatment abroad
Blood transfusions before 1991
What 3 features are more prominent in HBV than HAV if present?
How does HBV often present?
It's often asymptomatic; otherwise like a more severe HAV with prominent jaundice, rash and arthralgia
What blood tests indicate an acute HBV infection?
Acutely deranged LFTs
What 2 blood markers are only found during the acute phase of HBV infection?
What is HBV DNA used to monitor?
Treatment and infectivity
What unusual HBV marker is used to indicate high infectivity?
What blood tests indicate if someone has had a past HBV infection and recovered?
What blood test indicates someone who has been vaccinated against HBV?
HBsAb (but no HBcIgG)
What blood test is used as a screening test for HBV?
Someone is HBV DNA, HBsAg positive as well as HBcIgM positive and has deranged LFTs. Diagnosis?
Someone is positive only for HBsIg. Diagnosis?
Vaccinated therefore immune
Someone is positive for HBsIg and HBcIgG. Diagnosis?
Immune due to previous infection
Someone is positive for HBsAg, HBcIgG and HBeAb but negative for HBcIgM and HBsIg. Diagnosis?
What is the most likely outcome of HBV infection?
Complete recovery -
What LFT picture does Hep A give?
Hepatic damage + raised bilirubin
Apart from complete recovery and chronicity how else can HBV infection resolve?
What 3 blood tests indicate chronic HBV infection?
How is HCV spread?
Bloodborne, sexual, vertical
If hep C presents symptomatically, how does it present?
Milder flu-like illness with fever +/- jaundice
How is HCV infection detected in the acute phase?
HCV RNA (PCR) + deranged LFTs
How is chronic HCV infection detected?
What proportion of HCV goes on to become chronic? Future complications?
1/3 liver cirrhosis
Treatment of HCV? (Chronic)
PEG interferon alpha
Prevention of HBV?
Safe sex, clean needles, blood screening etc.
Is there a vaccine for HCV?
What is the role of Hep D virus infection?
Can only occur in context of HBV as it is an incomplete RNA virus
How is HDV spread?
In the blood
2 types of HDV infection?
Occurring at same time to make more severe infection (co-infection)
Causing flare up of chronic infection (superinfection)
Investigating HDV infection?
HDV RNA (PCR)
Treatment of HDV virus?
Alpha interferon (limited success)
Potential implications of HDV infection?
Increased risk of fulminant hepatitis and liver failure
But no chronic state
How is HDV prevented?
How is HEV spread?
But more like pork, deer, water supplies (and sexual)
Where is HEV common?
Symptoms of HEV?
Similar to HAV - icterus, flu like Sx, pruritis, organomegally
What are the 2 phases of HAV infection?
Prodromal phase (non-specific, nausea vom headaches etc.)
Icteric phase (jaundice, fever, pruritis etc.)
How is HEV infection detected?
HEV RNA serology (PCR) via serum or stool
In whom does HEV infection carry particular significance?
Pregnant women - mega high mortality
What food is implicated in HEV infection?
How is Hep A transmitted?
Fecal-oral route - contaminated food and water
Acute presentation of mastoiditis?
Often follows acute or recurrent OM, bulging erythematous TM
Otalgia, retroaural pain (swelling, redness, boggy)
Fever and malaise
Discharge and perforation
What CN and hearing findings might be consistent with mastoiditis?
CN5, 7, 8 involvement
Potential complications of mastoiditis?
Intracranial infection - meningitis, abscess
Subacute presentation of allergic extrinsic alveolitis?
Examples of allergic extrinsic alveolitis?
Farmers lung (hay)
Pigeon fanciers lung (feathers and avian proteins)
Cheese workers lung (penicillium casei)
Malt workers lung
Hot tub lung (mycobacterium Avium)
Signs of chronic allergic extrinsic alveolitis?
SOB and weight loss over time
Can lead to cor pulmonale
What are the most common viral meningitides?
Complications of childhood disease
3 most common causes of bacterial meningitis?
Haemophilus influenzae B
Bacterial meningitis with particular relevance in pregnancy?
Bacterial meningitis with particular relevance in neonates?
GBS (strep viridans)
Aseptic meningitis causes?
Viral or partially treated bacterial
Fungal - cryptococcus, aspergillus etc.
Parasitic e.g. Toxoplasma
Differentiating between meningitis and encephalitis signs and symptoms?
Encephalitis typically has more reduction in consciousness level +/- focal neurological signs, meningitis is more about the meningism
Features of cerebral abscess?
Swinging fever and signs
Signs of raised ICP - Papilloedema, postural headache, reduced consciousness
Focal signs - visual fields?
Quad of acute bacterial meningitis?
Neck stiffness and photophobia
Altered mental state
4 contraindications to LP for meningitis?
Any signs of ICP - risk of coning
Acutely reduced consciousness
Focal neurological signs
What LP findings does bacterial meningitis provide?
High exudative protein count
What LP findings does viral meningitis provide?
Slightly raised protein if at all
What LP findings does fungal or TB meningitis demonstrate?
Very high protein - chronicity
Normal or lowered glucose
Is LP is contraindicated acutely, what investigation should be done instead?
Urgent treatment if suspecting meningococcal sepsis?
Benpen IM ASAP before transfer etc.
Then start on ceftriaxone/cefotaxime
What prophylaxis is used for contacts of bacterial meningitis? Why?
Ciprofloxacin/Rifampicin - don't want to breed resistance to ceftriaxone
What is the most common viral encephalitis and what is its specific treatment?
HSV - IV aciclovir
What intracranial infection can result from childhood measles infection?
Subacute sclerosing panencephalitis
Differentiating between cellulitis and erysipelas?
Cellulitis goes deeper (down to deep subcut tissue) and has poorly demarcated borders; erysipelas typically has well demarcated borders and looks like a fiery red rash
RFs for cellulitis?
Skin lesions incl insect bites and athletes foot
Old age, venous insufficiency, obesity
Differentials for cellulitis/erysipelas?
Varicose eczema, venous insufficiency
Usual management of SSTIs?
Flucloxacillin to cover GAS, staph
What triad is suggestive of primary HIV infection?
Rash (palmar plantar?)
Pathophysiology behind HIV?
Retrovirus which binds to cells with CD4 receptors (T lymphocytes, macrophages, monocytes etc) spread by bloodborne contact (sex, needles etc.)
What diagnostic can be used in the acute HIV illness before Ab detection?
HIV RNA and p24 antigen
What diagnostic screen can be used for established HIV?
What is the first stage of illness in HIV?
Seroconversion illness few weeks post-infection - may be glandular fever like, with classic triad of fever rash and pharyngitis
What follows seroconversion in HIV illness?
Asymptomatic infection - slow replication with low viral load, cd4 count relatively unaffected
What follows completely asymptomatic infection in HIV and how is it defined?
Persistent generalised lymphadenopathy PGL
LNs >1cm in at least 2 non-inguinal sites persistent for at least 3 months with no other cause
What symptoms might be experienced in HIV as cd4 count starts to drop, alongside PGL?
Constitutional Sx - diarrhoea, weight loss, fever, night sweats
Opportunistic infections - oral hairy leukoplakia, oral thrush, VZV, recurrent HZV, seborrhoeic dermatitis
What 2 components are used to stage HIV in the CDC classification?
CD4 count and clinical category
CD4 divisions used in HIV staging? When is treatment generally started?
>500/mm3 = stage 1
200-499 = stage 2 (treatment when under 350)
Less than 200 = stage 3
What is category A in HIV staging?
Asymptomatic infection, including seroconversion or PGL
What is category B in HIV testing?
Symptomatic infection (incl constitutional Sx diarrhoea, fever) or opportunistic infections not meeting category C criteria, incl oral thrush and oral hairy leukoplakia and VZV, ITP
What is category C in HIV staging?
Presence of at least 1 AIDS defining condition
Which CDC classifications of HIV are indicative of AIDS?
A3, B3 and C1, C2 and C3
Common AIDS defining infections?
TB and other mycobacterium infections incl MAC
Pneumocystis jirovecii pneumonia
Toxoplasmosis infection (cerebral)
CMV retinitis, unusual EBV or HSV infections
Common AIDS defining cancers?
Invasive cervical carcinoma
Burkitts lymphoma (EBV)
Under what 3 circumstances can ART for HIV be started?
CD4 under 350
Nervous system involvement
AIDS defining condition
Under what circumstances may ART be started for HIV CD4 count between 350-500/mm3?
Present or likely CV disease
What vaccinations should be given in HIV? What should be avoided?
Generally everything possible apart from BCG and VZV
6 classes of ART?
Nucleoside reverse transcriptase inhibitors
Non-nucleoside reverse transcriptase inhibitors
What type of ART is majorly associated with lipodystrophy syndrome?
What complication can arise from ART? What is it?
Lipodystrophy syndrome - redistribution of fat from subcutaneous to central, increased insulin resistance and dislipidaemia
What type of ART should be avoided in concurrent hepatitis?
Nucleoside reverse transcriptase inhibitors
5 methods for preventing HIV spread?
Safe sexual practises
Needle exchange programmes
Blood screenings for transfusions
Screening during pregnancy
Post exposure prophylaxis
What is often implicated in acute infective COPD exacerbations? First line Rx?
Haemophilus - doxycycline
MARRFAW of infectious disease symptoms screen?
Fever and night sweats
TINVAPPS of broad areas of infectious disease RFs to ask about?
Travel - ask first and explore where when what who
Infectious contacts/food related
Needles - IVDU, blood transfusion, tattoos, medical Rx abroad
Previous major infection - BBVs and TB
Sexual Hx if appropriate
Previous hospital admission or indwelling devices
3 criteria for defining PUO?
Fever over 38.3 on several occasions over duration of illness
At least 3 weeks of illness
Failure to reach diagnosis after proper investigation at 2 OP visits or 3 days inpatient
Common cancers causing PUO?
Renal cell carcinoma
What might be the cause of PUO (and arthralgia, spinal tenderness) in a patient with Hx of cattle/sheep exposure and raw milk products?
What characterises oral thrush vs hairy oral leukoplakia?
Oral thrush comes off with scraping
What causes HIV associated retinitis at CD4 less than 50?
Cause of insidious fungal meningitis in HIV patient?
What virus causes HIV associated neurolymphoma?
Most common cerebral infection in HIV?
How does PCP pneumonia present?
Dry cough, SOBOE, night sweats - looks a bit like TB
What is the incubation period of gonorrhoea?
Up to 2 weeks
Rx for HPV?
Podophyllotoxin (podophyllin), cryotherapy, electrocautery or excision
When does secondary Syphillis infection occur?
1-2 months after primary chancre
2 features of congenital Syphillis?
Hutchinsons teeth (have little half moons in them)
What criteria is used in defining BV?
Amsel criteria 3/4 of:
Thin white discharge
KOH sniff test
pH over 4.5
Incubation and presentation of cholera?
3-4 days then abrupt onset severe diarrhoea, going from brown and water to Mucoid fluid alongside dehydration
What microscopy findings indicate cholera infection?
Comma shaped highly motile gram negative bacteria
What is yellow fever?
Another flavivirus a bit like dengue but slightly longer incubation
Early Sx of schistosomiasis?
Swimmers ish - skin irritation and rash
Second stage of schistosomiasis infection?
Invasive stage - dry cough, abdo pain, splenomegaly with eosinophilia
Chronic schistosomiasis infection?
Chronic diarrhoea and hepatomegaly, portal HTN etc.
Ova found in faeces
Rx for schistosomiasis?
Single dose praziquantel
Classical Sx of diphtheria?
Grey tough pseudomembrane on pharynx/tonsils
Fever, pharyngitis, mega cervical lymphadenopathy/oedema (Bulls neck sign), stridor, airway compromise
Defining features of giardiasis?
More common in well sanitised areas
Acute diarrhoea or chronic flatulence, grumbly intestinal Sx and early morning greasy/loose stools