Lecture 15: Infections Causing Jaundice Flashcards
3 ways that infectious diseases can cause jaundice
- obstructive jaundice
- hyperbilirubinaemia –> inflammation of hepatocytes –> hepatitis
- haemolysis –> RBC destruction –> excess Hb metabolism –> bilirubin end product
what way does malaria cause jaundice
haemolysis
what is a notifiable disease
disease that have potential risks to populations or public health and must be reported to public health authorities
name two viral infections that can cause hepatitis
- Epstein Barr Virus (EBV)
- Cytomegalovirus (CMV)
what is the most notable bacterial pathogen to cause bacterial hepatitis
leptospirosis
how are the different hep viruses spread
- A and E are faecal oral
- B C and D are blood borne spread by sexual contact, blood contaminated equipment or vertical transmission
which hep virus is a worldwide endemic
Hep A
how is Hep A transmitted
- faecal-oral
- food borne
- person to person in crowded circumstances
how is Hep A/Hep E diagnosed
- serological tests looking for HAV/HEV specific IgM
how is the spread of Hep A controlled
- improved sanitation
- vaccination
where in the world is Hep E more prevalent
Asian countries
how can Hep E be transmitted
- faecal-oral
- water borne
which people are particularly at risk of developing more severe hepatitis or persistent infection from Hep E
- pregnant women particularly at the end of pregnancy
- immunocompromised patients
how is Hep E treated
- no specific treatment
- no licensed
how is Hep C transmitted
- spread through blood
- blood contaminated equipment
what type of virus is Hep C and Hep A
RNA
- C –> enveloped RNA
- A –> single stranded RNA
why do many patients not know they are infected with Hep C/ infectious
Hep C causes notable jaundice in around 25% of ACUTE infections, and most people go on to have CHRONIC HCV infection
how is Hep C diagnosed
- serological w/ assays for both HCV antigens and antibodies
- HCV RNA can also be detected using PCR
how is Hep C treated
- treatment aims to reduce viral RNA detection in blood which reduces long term sequelae of chronic infection
- treatment still developing and is dependent on serotype patient is infected with
- pegylated interferon alpha sometimes used as part of primary treatment for HCV
- range of direct acting antiviral (DAA) drugs that target HCV specific enzymes e.g. viral protease
what type of virus is Hep B
double stranded DNA virus w/ reverse polymerase
how is Hep B transmitted
- blood borne
- vertical transmission (majority)
- sexual contact
what is the most prominent symptom of acute Hep B
jaundice –> occurs in 90% of people
how is Hep B capable of chronic carrier condition
has reverse transcriptase enzyme that allows integration of viral DNA unto human genome
what are the 3 important antigens of HBV
- HBsAg
- HBcAg
- HBeAg
what is looked for when doing blood tests for HBV
- 3 important antigens
- antibodies raised against antigens
- HBV DNA tested by PCR
what does the presence of HBsAg indicate
confirms infection and indicates infectivity of blood
what does presence of HBeAg indicate
signifies high infectivity and maybe be seen in acute infection or chronic carriers
what indicates successful vaccination against HBV
presence of HBsAb
- seen in patients who have recovered from acute infection and cleared virus from body
when does HBcAb develop
shortly after acute infection and persist in all patients
how is HBV prevented
- vaccination of at risk groups
- using single-use instruments e.g. needles
- decontamination of multiple use instruments
- screening pregnant women for HBsAg
- babies born to HBsAg +ve moms given prophylaxis w/ HBV immune globulin (passive immunisation)
how is HBV treated
- supportive and symptom relief measures
- pegylated interferon alpha
- nucleoside analogue drugs e.g. Entacavir and reverse transcriptase inhibitors e.g. Tenovovir
what is the aim of HBV treatment
prevention of liver cirrhosis + failure and hepatocellular carcinoma
how can HDV cause infection
can only replicate in cells already infected with HBV
- requires shell of HBsAg in order to bud from infected hepatocytes
how is HDV spread
- blood borne (same as B and C)
what does the presence of HDV in HBV infected patients indicate
disease is more severe
what type of jaundice occurs with biliary tree infection
obstructive jaundice
what makes the biliary tree vulnerable to infection
anatomy: gall bladder attached to duodenum which has a rich microbiome
what can cause obstruction of flow of bile
- gall stones
- intrinsic narrowing of biliary draining ducts
- extrinsic narrowing of biliary tree
- bile stasis –> bile does not flow or becomes thickened –> could occur in response to stress responses seen in sepsis/starvation/burns/trauma/major surgery
what organisms are most commonly seen assc. w/ biliary tree infection
- enterobacteriaceae e.g. E.coli
- enteric gram +ves e.g. enterococcus species
- anaerobes incl. bacteriodes species
how can biliary tree infection present as a public health risk
- salmonella (specific enterobacteriaceae) can colonise biliary tree
- may lead to chronic carrier states of salmonella species
- salmonella typhi (cause of typhoid fever) can be one
define cholecystitis
inflammation of gallbladder
define cholangitis
inflammation of biliary tract
give 2 clinical presentations of biliary tract infection
- cholecystitis
- cholangitis
give some risk factors for gallstones in biliary sepsis
- older age
- female
- low fibre diet
- obesity
name some characteristic symptoms of biliary infection
- pain localising to right upper quadrant
- pain may be severe and radiate to the back
- referred pain to right shoulder tip
- nausea and vomiting
- fever
- abdominal tenderness
- local peritonitis –> both reflex guarding and rebound tenderness
- Murphy’s sign –> patient can’t breathe in comfortably when examiner’s hand placed along right costal margin (suggests cholecystitis)
management of biliary tract infection
- source control
- endoscopic retrograde cholangio-pancreatography (ERCP)
- antibiotics e.g. beta-lactam/ beta-lactase inhibitor combinations are first line treatment –> Co-amoxiclav and Piperacillin inhibitor
- Piperacillin-tazobactam reserved for more severe presentations
- vancomycin, aztreonam, and metronidazole may be used for penicillin-allergic patients
define abscess
destruction of normal tissue structure due to infection, and replacement of normal structure with pus and necrotic tissue
why can antibiotics not reach therapeutic level within abscess collections
collections are relatively avascular and tend to have low pH
name 3 infective aetiologies that can cause liver abscess
- bacteria –> when infection drains into liver via portal system
- amoeba –> food/water borne
- helminths –> worms e.g. dog tapeworm
liver abscess management
- management follows aetiology
- source control
- drainage
- polymicrobial infection without drainage needs long course of high dose broad spectrum antibiotics
- amoeba treated w/ metronidazole
why does drainage of hydatid cysts require specialist management
contents can lead to anaphylaxis and death
define zoonosis/zoonotic
infectious disease that is transmissible from animals to humans e.g. anthrax, brucellosis
define vector
a living intermediary that carries an agent from reservoir to a susceptible host e.g. mosquitoes, fleas or ticks
name some key vector borne diseases and zoonoses
- malaria
- dengue
- lyme
- plague
- q-fever (caused by Coxiella Burnetti)
- brucellosis (caused by brucella species, notably brucella abortus)
- leptospirosis (most common bacterial cause of primary jaundice)
how does leptospirosis cause human infection
- assc. w/ contaminated water/food –> water contaminated w/ rat urine
- organisms enter through skin breaks or mucosae
clinical infection of leptospirosis
- ‘bi-phasic illness’
- pyrexial or flu-like illness
- more severe cases involve immune mediated haemorrhagic complications –> Weil’s disease –> haemorrhagic complications due to low platelets, kidney and liver failure –> hepatitis, jaundice, haemorrhage, meningitis
how to diagnose leptospirosis
serology
leptospirosis treatment
doxycycline
penicillins also effective
Weil’s disease triad
- thrombocytopenia
- jaundice
- renal failure
what kind of diseases are notifiable
- those w/ epidemic potential
- food-borne threats
- rare, serious and imported infections
