Infectious diseases Flashcards
Inactivated vaccines
WHat is it
involve giving a killed version of the pathogen
Inactivated vaccines involve giving a killed version of the pathogen. They cannot cause an infection and are safe for immunocompromised patients, although they may not have an adequate response. Examples are:
- Polio
- Flu vaccine
- Hepatitis A
- Rabies
Subunit and conjugate vaccines only contain parts of the organism used to stimulate an immune response. They also cannot cause infection and are safe for immunocompromised patients. Examples of subunit and conjugate vaccines are:
- Pneumococcus
- Meningococcus
- Hepatitis B
- Pertussis (whooping cough)
- Haemophilus influenza type B
- Human papillomavirus (HPV)
- Shingles (herpes-zoster virus)
Live attenuated vaccines contain a weakened version of the pathogen. They are still capable of causing infection, particularly in immunocompromised patients. The following vaccines are live attenuated vaccines:
- Measles, mumps and rubella vaccine: contains all three weakened viruses
- BCG: contains a weakened version of tuberculosis
- Chickenpox: contains a weakened varicella-zoster virus
- Nasal influenza vaccine (not the injection)
- Rotavirus vaccine
Toxin vaccines contain a toxin that is normally produced by a pathogen. They cause immunity to the toxin and not the pathogen itself. Examples are ……
. Examples are the diphtheria and tetanus vaccines.
Vaccine Schedule
The HPV vaccine is ideally given to girls and boys before they become sexually active. The intention is to prevent them contracting and spreading HPV once they become sexually active. The current NHS vaccine is Gardasil, which protects against strains
6, 11, 16 and 18
The BCG vaccine is offered from_____ to babies who are at higher risk of ________ These are babies with relatives from countries of high TB prevalence or who live in urban areas with a high rate of TB. It may also be given to children arriving from areas of high TB prevalence or in close contact with people that have TB.
The BCG vaccine is offered from birth to babies who are at higher risk of tuberculosis. These are babies with relatives from countries of high TB prevalence or who live in urban areas with a high rate of TB. It may also be given to children arriving from areas of high TB prevalence or in close contact with people that have TB.
Who thought there was a link between MMR and Autism
Andrew Wakefield
Pathophysiology of Paediatric Spesis
The causative pathogens are recognised by_________, __________ and _____ cells. These cells release vast amounts of cytokines, such as ________ and tumor necrosis factor, to alert the immune system to the invader. These cytokines activate other parts of the immune system. This immune activation leads to further release of chemicals such as _____ ______ that causes _________. The immune response causes inflammation throughout the body.
Many of these cytokines cause the ________ ______ of blood vessels to become more ________. This causes fluid to leak out of the blood into the extracellular space, leading to ______ and a reduction in __________ volume. The oedema around blood vessels creates a space between the blood and the tissues, reducing the amount of oxygen that reaches the tissues.
Activation of the _________ system leads to deposition of ____ throughout the circulation, further compromising organ and tissue perfusion. It also leads to consumption of _______ and _______ _____, as they are being used up to form the blood clots. This leads to ____________, haemorrhages and an inability to form clots and stop bleeding. This is called __________ ________ ________ (DIC).
Blood _____ rises as a result of anaerobic respiration in the hypo-perfused tissues with an inadequate oxygen. A ______ _______ of anaerobic respiration is lactate.
The causative pathogens are recognised by macrophages, lymphocytes and mast cells. These cells release vast amounts of cytokines, such as interleukins and tumor necrosis factor, to alert the immune system to the invader. These cytokines activate other parts of the immune system. This immune activation leads to further release of chemicals such as nitrous oxide that causes vasodilation. The immune response causes inflammation throughout the body.
Many of these cytokines cause the endothelial lining of blood vessels to become more permeable. This causes fluid to leak out of the blood into the extracellular space, leading to oedema and a reduction in intravascular volume. The oedema around blood vessels creates a space between the blood and the tissues, reducing the amount of oxygen that reaches the tissues.
Activation of the coagulation system leads to deposition of fibrin throughout the circulation, further compromising organ and tissue perfusion. It also leads to consumption of platelets and clotting factors, as they are being used up to form the blood clots. This leads to thrombocytopenia, haemorrhages and an inability to form clots and stop bleeding. This is called disseminated intravascular coagulopathy (DIC).
Blood lactate rises as a result of anaerobic respiration in the hypo-perfused tissues with an inadequate oxygen. A waste product of anaerobic respiration is lactate.
WHat is Septic SHock
How should it be treated
Septic shock is diagnosed when sepsis has lead to cardiovascular dysfunction. The arterial blood pressure falls, resulting in organ hypo-perfusion. This leads to a rise in blood lactate as the organs begin anaerobic respiration.
Septic shock should be treated aggressively with IV fluids to improve the blood pressure and tissue perfusion. If IV fluid boluses fail to improve the blood pressure and lactate level, children should be escalated to the high dependency or intensive care unit where medication called inotropes (such as noradrenalin) can be considered. Inotropes stimulate the cardiovascular system and improve blood pressure and tissue perfusion.
Signs of Sepsis
Don’t underestimate observing the child from the end of the bed. Consider whether they look well or unwell.
Hard signs to look out for that can indicate sepsis are:
- Deranged physical observations
- Prolonged capillary refill time (CRT)
- Fever or hypothermia
- Deranged behaviour
- Poor feeding
- Inconsolable or high pitched crying
- High pitched or weak cry
- Reduced consciousness
- Reduced body tone (floppy)
- Skin colour changes (cyanosis, mottled pale or ashen)
Shock involves circulatory collapse and hypoperfusion of organs.
Risk Assessment
There are NICE guidelines from 2019 that cover the assessment of children under 5 year with a fever. They recommend using a traffic light system for the assessment of serious illness in these children. This categorises children as green (low risk), amber (intermediate risk) or red (high risk). Read through the table in the NICE guidelines describing the features of each to familiarise yourself with the signs to look out for. Patients are categorised based on examination findings in various systems:
- Colour: normal colour versus cyanosis, mottled pale or ashen
- Activity: active, happy and responsive versus abnormal responses, drowsy or inconsolable cry
- Respiratory: normal breathing versus respiratory distress, tachypnoea or grunting
- Circulation and hydration: normal skin and moist membranes versus tachycardia, dry membranes or poor skin turgor
- Other: other concerning signs, such as fever > 5 days, non blanching rash, seizures or high temperatures < 6 months
It is worth remembering that all infants under __ _______ with a temperature of ___ or above need to be treated urgently for sepsis, until proven otherwise.
It is worth remembering that all infants under 3 months with a temperature of 38ºC or above need to be treated urgently for sepsis, until proven otherwise.
Sepsis is a medical emergency and needs to be managed urgently. Call for senior help early for experienced support
- Give oxygen if the patient has evidence of shock or oxygen saturations are below 94%
- Obtain IV access (cannulation)
- Blood tests, including a FBC, U&E, CRP, clotting screen (INR), blood gas for lactate and acidosis
- Blood cultures, ideally before giving antibiotics
- Urine dipstick and laboratory testing for culture and sensitivities
- Antibiotics according to local guidelines. They should be given within 1 hour of presentation.
- IV fluids. 20ml/kg IV bolus of normal saline if the lactate is above 2 mmol/L or there is shock. This may be repeated.
Additional investigations may be performed depending on the suspected sepsis infection:
- Chest xray if pneumonia is suspected
- Abdominal and pelvic ultrasound if intra-abdominal infection is suspected
- Lumbar puncture if meningitis is suspected
- Meningococcal PCR blood test if meningococcal disease is suspected
- Serum cortisol if adrenal crisis is suspected
What is meningitis
Meningitis is defined as inflammation of the meninges. The meninges are the lining of the brain and spinal cord. This inflammation is usually due to a bacterial or viral infection.
Neisseria meningitidis is a _____ _____ _________ bacteria. They are circular bacteria (cocci) that occur in pairs (diplo-). It is commonly known as meningococcus.
Neisseria meningitidis is a gram-negative diplococcus bacteria. They are circular bacteria (cocci) that occur in pairs (diplo-). It is commonly known as meningococcus.
What is Meningococcal septicaemia
Meningococcal septicaemia refers to the meningococcus bacterial infection in the bloodstream. Meningococcal refers to the bacteria and septicaemia refers to infection in the blood stream. Meningococcal septicaemia is the cause of the classic “non-blanching rash” that everybody worries about. This rash indicates the infection has caused disseminated intravascular coagulopathy (DIC) and subcutaneous haemorrhages.
Meningococcal meningitis is when the bacteria is infecting the _____ and the _________ ______ around the brain and spinal cord.
Meningococcal meningitis is when the bacteria is infecting the meninges and the cerebrospinal fluid around the brain and spinal cord.
What is MC of Bacterial Meningitis
The most common causes of bacterial meningitis in children and adults are Neisseria meningitidis (meningococcus) and Streptococcus pneumoniae (pneumococcus).
Most common cause of bacterial meningitis in neonates
In neonates the most common cause is group B strep (GBS). GBS is usually contracted during birth from GBS bacteria that live harmlessly in the mother’s vagina.
Presentation of meningitis
Typical symptoms of meningitis are fever, neck stiffness, vomiting, headache, photophobia, altered consciousness and seizures. Where there is meningococcal septicaemia children can present with a non-blanching rash. Other causes of bacterial meningitis do not usually cause the non-blanching rash.
Neonates and babies can present with very non-specific signs and symptoms, such as hypotonia, poor feeding, lethargy, hypothermia and a bulging fontanelle.
NICE recommend a lumbar puncture as part of the investigations for all children:
- Under 1 month presenting with fever
- 1 to 3 months with fever and are unwell
- Under 1 year with unexplained fever and other features of serious illness
There are two special tests you can perform to look for meningeal irritation:
Kernig’s test
Brudzinski’s test
What is Kernig’s test
Kernig’s test involves lying the patient on their back, flexing one hip and knee to 90 degrees and then slowly straightening the knee whilst keeping the hip flexed at 90 degrees. This creates a slight stretch in the meninges. Where there is meningitis it will produce spinal pain or resistance to movement.
What is Brudzinski’s test
Brudzinski’s test involves lying the patient flat on their back and gently using your hands to lift their head and neck off the bed and flex their chin to their chest. In a positive test this causes the patient to involuntarily flex their hips and knees.
Children seen in the primary care setting with suspected meningitis AND a non blanching rash should receive an urgent stat injection (IM or IV) of __________ prior to transfer to hospital, as time is so important. The dose will depending on their age.
Giving antibiotics should not delay transfer to hospital. Where there is a true penicillin allergy, transfer should be the priority rather than finding alternative antibiotics.
Children seen in the primary care setting with suspected meningitis AND a non blanching rash should receive an urgent stat injection (IM or IV) of benzylpenicillin prior to transfer to hospital, as time is so important. The dose will depending on their age.
Giving antibiotics should not delay transfer to hospital. Where there is a true penicillin allergy, transfer should be the priority rather than finding alternative antibiotics.
Hospital management of meningitis
lumbar puncture for cerebrospinal fluid (CSF) should be performed prior to starting antibiotics,.
Send blood tests for meningococcal PCR if meningococcal disease is suspected. This tests directly for the meningococcal DNA.
There should be a low threshold for treating suspected bacterial meningitis, particularly in babies and younger children.
Always follow the local guidelines regarding the choice of antibiotic. Typical antibiotics are:
- Under 3 months – cefotaxime plus amoxicillin (the amoxicillin is to cover listeria contracted during pregnancy)
- Above 3 months – ceftriaxone
Vancomycin should be added to these antibiotics if there is a risk of penicillin resistant pneumococcal infection, for example recent foreign travel or prolonged antibiotic exposure.
Steroids are also used in bacterial meningitis to reduce the frequency and severity of hearing loss and neurological damage. Dexamethasone is given 4 times daily for 4 days to children over 3 months if the lumbar puncture is suggestive of bacterial meningitis.
Bacteria meningitis and meningococcal infection are notifiable diseases, so public health need to be informed of all cases.
The most common causes of viral meningitis are
herpes simplex virus (HSV), enterovirus and varicella zoster virus (VZV).
A sample of the CSF from the lumbar puncture should be sent for viral PCR testing.
Viral meningitis tends to be _____ than bacterial and often only requires supportive treatment. ______ can be used to treat suspected or confirmed HSV or VZV infection.
Viral meningitis tends to be milder than bacterial and often only requires supportive treatment. Aciclovir can be used to treat suspected or confirmed HSV or VZV infection.
A lumbar puncture involves inserting a needle into the lower back to collect a sample of cerebrospinal fluid (CSF). The spinal cord ends at the L1 – L2 vertebral level, so the needle is usually inserted into the L3 – L4 intervertebral space. Samples are sent for ________ _____, _____ _______, ____ ______, _____ and ______-.
A lumbar puncture involves inserting a needle into the lower back to collect a sample of cerebrospinal fluid (CSF). The spinal cord ends at the L1 – L2 vertebral level, so the needle is usually inserted into the L3 – L4 intervertebral space. Samples are sent for bacterial culture, viral PCR, cell count, protein and glucose.
Compare cerebrospinal fluid : bacterial and viral
Comment on Appearance, protein, glucose, WBC, Culture
Complications of meningitis
- Hearing loss is a key complication
- Seizures and epilepsy
- Cognitive impairment and learning disability
- Memory loss
- Cerebral palsy, with focal neurological deficits such as limb weakness or spasticity
WHat is Encephalitis
Encephalitis means inflammation of the brain. This can be the result of infective or non-infective causes. Non-infective causes are autoimmune, meaning antibodies are created that target brain tissue.
Paediatric Encephalitis most common causes
The most common cause is infection with a virus. Bacterial and fungal encephalitis is also possible although much more rare in the UK. The most common viral cause is herpes simplex virus (HSV). In children the most common cause is herpes simple type 1 (HSV-1) from cold sores. In neonates it is herpes simplex type 2 (HSV-2) from genital herpes, contracted during birth.
Other viral causes include varicella zoster virus (VZV) associated with chickenpox, cytomegalovirus associated with immunodeficiency, Epstein-Barr virus associated with infectious mononucleosis, enterovirus, adenovirus and influenza virus. It is important to ask about vaccinations, as the polio, mumps, rubella and measles viruses can cause encephalitis as well.
Encephalitis in Children
Presentation
- Altered consciousness
- Altered cognition
- Unusual behaviour
- Acute onset of focal neurological symptoms
- Acute onset of focal seizures
- Fever
Children with features of encephalitis need some key investigations to establish the diagnosis:
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- Lumbar puncture, sending cerebrospinal fluid for viral PCR testing
- CT scan if a lumbar puncture is contraindicated
- MRI scan after the lumbar puncture to visualise the brain in detail
- EEG recording can be helpful in mild or ambiguous symptoms but is not always routinely required
- Swabs of other areas can help establish the causative organism, such as throat and vesicle swabs
- HIV testing is recommended in all patients with encephalitis
Contraindications to a lumbar puncture include a
Contraindications to a lumbar puncture include a GCS below 9, haemodynamically unstable, active seizures or post-ictal.
Management of Paediatric Encephalitis
Intravenous antiviral medications are used to treat the suspected or confirmed underlying cause:
- Aciclovir treats herpes simplex virus (HSV) and varicella zoster virus (VZV)
- Ganciclovir treat cytomegalovirus (CMV)
Repeat lumbar puncture is usually performed to ensure successful treatment prior to stopping antivirals
Aciclovir is usually started empirically in suspected encephalitis until results are available. Other viral causes have no effective treatment and management is supportive.
Followup, support and rehabilitation is required after encephalitis, with help managing the complications.
Complications of Encephalitis
- Lasting fatigue and prolonged recovery
- Change in personality or mood
- Changes to memory and cognition
- Learning disability
- Headaches
- Chronic pain
- Movement disorders
- Sensory disturbance
- Seizures
- Hormonal imbalance
Infectious mononucleosis (IM) is a condition caused by infection with the _____ ____ ______. It is commonly known as the _______ ______, ________ _____ or “mono”. This virus is found in the _____ of infected individuals. Infection may be spread by ______ or by sharing cups, toothbrushes and other equipment that transmits saliva.
Infectious mononucleosis (IM) is a condition caused by infection with the Epstein Barr virus (EBV). It is commonly known as the “kissing disease”, “glandular fever” or “mono”. This virus is found in the saliva of infected individuals. Infection may be spread by kissing or by sharing cups, toothbrushes and other equipment that transmits saliva.
Exam presentation of Infectious mononucleosis
Look out for the exam question that describes an adolescent with a sore throat, who develops an itchy rash after taking amoxicillin. Mononucleosis causes an intensely itchy maculopapular rash in response to amoxicillin or cefalosporins.
Features Infectious Mononucleosis (Glandular Fever)
Fever
Sore throat
Fatigue
Lymphadenopathy (swollen lymph nodes)
Tonsillar enlargement
Splenomegaly and in rare cases splenic rupture
WHat are Heterophile Antibodies
In certain diseases (such as HIV) we can test for specific antibodies to the disease. That way we know the body has come in contact with the disease and launched an immune response to it. In infectious mononucleosis, the body produces something called heterophile antibodies, which are antibodies that are more multipurpose and not specific to the EBV antigens. It takes up to 6 weeks for these antibodies to be produced.
We can test for these heterophile antibodies using two tests:
- Monospot test: this introduces the patient’s blood to red blood cells from horses. Heterophile antibodies (if present) will react to the horse red blood cells and give a positive result.
- Paul-Bunnell test: this is similar to the monospot test but uses red blood cells from sheep.
These tests are almost 100% specific for infectious mononucleosis, however not everyone who has IM produces heterophile antibodies, and it can take up to six weeks for the antibodies to be produced. Therefore they are only 70 – 80% sensitive.
It is possible to test for specific EBV antibodies. These antibodies target something called viral capsid antigen (VCA):
- The IgM antibody rises early and suggests acute infection
- The IgG antibody persists after the condition and suggests immunity
Management and Prognosis
Infectious mononucleosis
Infectious mononucleosis is usually self limiting. The acute illness lasts around 2 – 3 weeks, however it can leave the patient with fatigue for several months once the infection is cleared.
Patients are advised to avoid alcohol, as EBV impacts the ability of the liver to process the alcohol. Patients are advised to avoid contact sports due to the risk of splenic rupture. Emergency surgery is usually required if splenic rupture occurs.
Complications of glandular fever
- Splenic rupture
- Glomerulonephritis
- Haemolytic anaemia
- Thrombocytopenia
- Chronic fatigue
EBV infection is associated with certain cancers, notable Burkitt’s lymphoma.
What is mumps
Mumps is a viral infection spread by respiratory droplets. The incubation period is 14 – 25 days. Mumps is usually a self limiting condition that lasts around 1 week. Management is supportive, and involves treating the complications if they occur.
Taking a vaccination history is essential when considering a diagnosis of mumps. The MMR vaccine offers around 80% protection against mumps.
Presentation of mumps
Patients experience an initial period of flu-like symptoms known as the prodrome. These occur a few days before the parotid swelling:
- Fever
- Muscle aches
- Lethargy
- Reduced appetite
- Headache
- Dry mouth
Parotid gland swelling, either unilateral or bilateral, with associated pain is the key feature that should make you consider mumps.
mumps can also present with symptoms of the complications, such as:
- Abdominal pain (pancreatitis)
- Testicular pain and swelling (orchitis)
- Confusion, neck stiffness and headache (meningitis or encephalitis)
Management of glandular fever
The diagnosis can be confirmed using PCR testing on a saliva swab. The blood or saliva can also be tested for antibodies to the mumps virus.
Mumps is a notifiable disease, meaning you need to notify public health of any suspected and confirmed cases.
Management is supportive, with rest, fluids and analgesia. Mumps is a self limiting condition. Management of complications is also mostly supportive.
Complications of mumps
Pancreatitis
Orchitis
Meningitis
Sensorineural hearing loss
Basic Pathophysiology of HIV
HIV is an RNA retrovirus. HIV-1 is most common type. HIV-2 is rare outside West Africa. The virus enters and destroys the CD4 T helper cells. An initial seroconversion flu like illness occurs within a few weeks of infection. The infection is then asymptomatic until it progresses and the patient becomes immunocompromised and beings developing AIDS defining illnesses and opportunistic infections, potentially years later.
HIV can not be spread through normal day to day activities, including kissing. It is spread through:
- Unprotected anal, vaginal or oral sexual activity
- Mother to child at any stage of pregnancy, birth or breastfeeding. This is referred to as vertical transmission.
- Mucous membrane, blood or open wound exposure to infected blood or bodily fluids. This could be through sharing needles, needle-stick injuries or blood splashed in an eye.
Preventing Transmission of HIV During Birth
Mode of delivery will be determined by the mother viral load:
- Normal vaginal delivery is recommended for women with a viral load < 50 copies / ml
- Caesarean sections are considered in patients with > 50 copies copies / ml and in all women with > 400 copies / ml
- IV zidovudine should be given during the caesarean if the viral load is unknown or there are > 10000 copies / ml
Prophylaxis treatment may be given to the baby depending on the mothers viral load:
- Low risk babies, where mums viral load is < 50 copies per ml, should be given zidovudine for 4 weeks
- High risk babies, where mums viral load is > 50 copies / ml, should be given zidovudine, lamivudine and nevirapine for 4 weeks
Can HIV be transmitted through breast feeding
HIV can be transmitted during breastfeeding, even if the mother’s viral load is undetectable. Breastfeeding is never recommended for mothers with HIV, however if the mum is adamant and the viral load is undetectable, sometimes it is attempted with close monitoring by the HIV team
Testing for HIV
- HIV antibody screen: this tests whether the immune system has created antibodies due to exposure to the HIV virus. This is the standard screening test, but it can give false positive in babies of HIV positive mums, due to maternal antibodies that cross the placenta. It can take up to 3 months for antibodies to develop after exposure to the virus.
- HIV viral load: this tests directly for viruses in the blood. This will never be falsely positive, but may come back as “undetectable” in patients on antiretroviral therapy.
What should you do before testing for HIV
Testing can be done by any doctor, nurse or other trained person. Informed consent should be documented before testing. It is good practice to involve both parents and child when getting consent for testing. Results should be given in person, by a suitably knowledgable clinician. Positive results may be due to maternal antibodies in children aged under 18 months. This does not necessarily mean they are HIV positive. Discuss results with an infectious disease specialist before informing parents that the child has HIV.
When to test for HIV
- Babies to HIV positive parents
- When immunodeficiency is suspected, for example where there are unusual, severe or frequent infections
- Young people who are sexually active can be offered testing if there are concerns
- Risk factors such as needle stick injuries, sexual abuse or IV drug use
Testing in Children to HIV Positive Parents
- HIV viral load test at 3 months. If this is negative, the child has not contracted HIV during birth and will not develop HIV unless they have further exposure.
- HIV antibody test at 24 months. This is to assess whether they have contracted HIV since their 3 month viral load, for example through breast feeding. If the 3 month test is negative and they are not breastfed, this should be negative.
Note that the antibody test can be positive in infants who do not have HIV for up to 18 months of age. This is due to maternal antibodies that have crossed the placenta during pregnancy.
Treatment should be coordinated by a specialist in paediatric HIV. The key principles of medical care are:
- Antiretroviral therapy (ART) to suppress the HIV infection
- Normal childhood vaccines, avoiding or delaying live vaccines if severely immunosuppressed.
- Prophylactic co-trimoxazole (Septrin) for children with low CD4 counts, to protect against pneumocystis jirovecii pneumonia (PCP)
- Treatment of opportunistic infection
WHat is the aim of aim of antiretroviral therapy (ART)
The aim of antiretroviral therapy (ART) is to achieve a normal CD4 count and undetectable viral load. As a general rule, when a patient has a normal CD4 and undetectable viral load on ART, treat their physical health problems (e.g. routine chest infections) as you would an HIV negative patient. When prescribing medications check for interactions with the HIV therapy.
The paediatric HIV multidisciplinary team should be involved in:
- Regular follow up to monitor growth and development
- Dietician input for nutritional support when required
- Parental education about the condition
- Disclosing the diagnosis to the child is often delayed until they are mature enough
- Psychological support
- Specific sex education in relation to HIV when appropriate
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What is Hep B
How is it transmitted
WHat is this type of transmission called
Hepatitis B is a DNA virus.
It is transmitted by direct contact with blood or bodily fluids. This may occur during sexual intercourse or sharing needles, for example amongst IV drug users or tattoos. It can also be passed through sharing contaminated household products such as toothbrushes or contact between minor cuts or abrasions. It can also be passed from mother to child during pregnancy and delivery. This is known as vertical transmission.
What do these viral markers suggest
- Surface antigen (HBsAg) –
- E antigen (HBeAg) –
- Core antibodies (HBcAb) –
- Surface antibody (HBsAb) –
- Hepatitis B virus DNA (HBV DNA) –
- Surface antigen (HBsAg) – active infection
- E antigen (HBeAg) – marker of viral replication and implies high infectivity
- Core antibodies (HBcAb) – implies past or current infection
- Surface antibody (HBsAb) – implies vaccination or past or current infection
- Hepatitis B virus DNA (HBV DNA) – this is a direct count of the viral load
When screening for hepatitis B, test HBcAb (for previous infection) and HBsAg (for active infection). If these are positive do further testing for______ and ______ _____
When screening for hepatitis B, test HBcAb (for previous infection) and HBsAg (for active infection). If these are positive do further testing for HBeAg and viral load (HBV DNA).
Which viral marker distinguish between acute, chronic and past infection
HBcAb
HBcAb can help distinguish between acute, chronic and past infection. We can measure IgM and IgG versions of the HBcAb. IgM implies an active infection and will give a high titre with an acute infection and a low titre with a chronic infection. IgG indicates a past infection where the HBsAg is negative.
HBeAg is important. Where the HBeAg is present it implies the patient is in an
acute phase of the infection where the virus is actively replicating. The level of HBeAg correlates with their infectivity. If the HBeAg is higher, they are highly infectious to others. When they HBeAg is negative but the HBeAb is positive, this implies they have been through a phase where the virus was replicating but the virus has now stopped replicating and they are less infectious.
Which Children to Test for hep B
- Children of hepatitis B positive mums (screen at 12 months of age or any time after that)
- Migrants from endemic areas
- Close contacts of patients with hepatitis B
To reduce the risk of the baby contracting hepatitis B, at birth (within 24 hours) neonates with hepatitis B positive mothers should be given both:
Hepatitis B vaccine
Hepatitis B immunoglobulin infusion
Can you find Hep B in breast milk
The hepatitis B virus can be found in the breast milk of mothers with hepatitis B. Babies of these mothers have already been exposed to the virus during pregnancy and birth. They should also receive the hepatitis B vaccine and hepatitis B immunoglobulin infusion. Therefore, the general advice is that it is safe for hepatitis B positive mother to breastfeed provided their babies are properly vaccinated.
Management for hep B
Most children with chronic hepatitis B are asymptomatic and do not require treatment. They require regular specialist follow up to assess monitor their serum ALT, HbeAg, HBV DNA, physical examination and liver ultrasound.
Where there is evidence of hepatitis or cirrhosis, treatment with antiviral medications may be considered.
What tyoe of virus is HEp C
how is it spread
Hepatitis C is an RNA virus.
It is spread by blood and bodily fluids. No vaccine is available. It is now curable in adults, using direct acting antiviral medications. These treatments are not yet available for children.
Complications: of Hep C
- Liver cirrhosis and associated complications of cirrhosis
- Hepatocellular carcinoma
Management in Children with hep c
Babies to hepatitis C positive mothers are tested at 18 months of age using the hepatitis C antibody test. Breastfeeding has not been found to spread hepatitis C, so mothers are free to breastfeed their babies. If nipples become cracked or bleed breastfeeding should temporarily stop whilst they heal.
Children often clear the virus spontaneously. Chronic infection with hepatitis C does not usually cause issues in childhood. Infected children will require regular specialist follow up to monitor their liver function and hepatitis C viral load.
Medical treatment may be considered in children over 3 years. Treatment in childhood involves pegylated interferon and ribavirin, which are less effective and well tolerated compared with the adult treatments.
Treatment is typically delayed until adulthood unless the child is significantly affected, because children are usually asymptomatic and newly available treatment for adults is highly effective
What is Kawasaki disease
Kawasaki disease is also known as mucocutaneous lymph node syndrome. It is a systemic, medium-sized vessel vasculitis. It affects young children, typically under 5 years. There is no clear cause or trigger. It is more common in Asian children, particularly Japanese and Korean children. It is also more common in boys. A key complication is coronary artery aneurysm.
Kawasaki Disease
Clinical Features
A key feature that should make you consider Kawasaki disease is a persistent high fever (above 39ºC) for more than 5 days. Children will be unhappy and unwell. The key skin findings are a widespread erythematous maculopapular rash and desquamation (skin peeling) on the palms and soles.
Other features include:
- Strawberry tongue (red tongue with large papillae)
- Cracked lips
- Cervical lymphadenopathy
- Bilateral conjunctivitis
TOM TIP: If you come across a child with a fever persisting for more than 5 days, think of Kawasaki disease! A rash, strawberry tongue, lymphadenopathy and conjunctivitis will seal the diagnosis in your exams.
There are several investigations that can be helpful in Kawasaki disease:
- Full blood count can show anaemia, leukocytosis and thrombocytosis
- Liver function tests can show hypoalbuminemia and elevated liver enzymes
- Inflammatory markers (particularly ESR) are raised
- Urinalysis can show raised white blood cells without infection
- Echocardiogram can demonstrate coronary artery pathology
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There are three phases to Kawasaki disease:
- Acute phase: The child is most unwell with the fever, rash and lymphadenopathy. This lasts 1 – 2 weeks.
- Subacute phase: The acute symptoms settle, the desquamation and arthralgia occur and there is a risk of coronary artery aneurysms forming. This lasts 2 – 4 weeks.
- Convalescent stage: The remaining symptoms settle, the blood tests slowly return to normal and the coronary aneurysms may regress. This last 2 – 4 weeks.
There are two first line medical treatments given to patients with Kawasaki disease:
- High dose aspirin to reduce the risk of thrombosis
- IV immunoglobulins to reduce the risk of coronary artery aneurysms
Patients will need close follow up with echocardiograms to monitor for evidence of coronary artery aneurysms.
TOM TIP: Kawasaki disease is one of the few scenarios where aspirin is used in children. Aspirin is usually avoided due to the risk of Reye’s syndrome. This is a unique fact that examiners like to test.
