Japanese Encephalitis (JE) is an infective illness cause by the mosquito-borne arbovirus Japanese Encephalitis Virus (JEV). It is endemic to the Asia-Pacific region, and recently it has become more widespread in Australia –  due to warmer and wetter conditions as a result of climate change.

Many infections are asymptomatic (thought to be >99%) but in those with symptoms there is high morbidity and mortality.

Symptoms start 5-15 days after infection, and are often non-specific in the first few days, induing diarrhoea and headaches. Then significant neurological features appears – including headache, altered mental state, focal neurological symptoms and seizures.

The fatality rate ranges from 5-50% – with an agreed estimated rate of 18%. Half of those who survive have long-term neurological deficits.

• When referring to JE – this typically refers to symptomatic cases
• When referring to JEV this typically refers to all infections

Outbreaks in humans are often closely associated with pigs and pig farming.

The most effective way to reduce the risk of the illness is to take measures to avoid mosquito bites – such as using repellants, wearing long clothing, and reducing mosquito breeding sites – e.g. by removing areas of stagnant water around your home.

A Japanese Encephalitis vaccine is available and recommended for those who travel to high risk areas or have a high risk of exposure (e.g. farm workers).

Epidemiology

• Japanese Encephalitis is of the most important causes of infective encephalitis worldwide
• On average thought that >99% of infections of JEV are asymptomatic but estimates vary widely from 1 in 25 to 1 in 1000 infected individuals who experience symptoms
  • It is thought that in populations not previously exposed to the virus the incidence of symptomatic infections is greater
• Thought to be about 100 000 symptomatic cases of JE worldwide each year
• Cases generally occur rurally in areas with rice farming – as this provides excellent conditions for mosquito habitat
• Cases also associated with pig farming  – this is the more common scenario is Australia where rice is not typically grown commercially
• Cases peak in the wet season when mosquito populations are highest

Virus transmission

JEV is a single stranded RNA virus of the family Flaviviridae. There are 5 known genotypes. Type IV is most prevalent in Australia.

JEV infects multiple animal hosts including wading birds – but pigs are the most important – especially in regards to infecting humans. Humans and horses are “dead-end hosts” and are not involved in the continuation of the cycle of infection.

Transmission between animals and humans happens via mosquitoes. In Australia the mosquito species most commonly involved is Culex annulirostris which can travel several kilometres a day.

An infected pig has a high viral load for 3-5 days – which enables ongoing transmission to mosquitos. Farmed pigs in close proximity to humans pose a particular problems – as there is often a high turnover – meaning there is little time for immunity to develop. Even in areas where farmed pigs have been removed JEV cases have been known to persist – probably due to feral pig populations.

The incubation period is about 5-15 days.

Presentation

• 5-15 days after infection
• Initially – non-specific viral symptoms, including:
  • Fever +/- rigors
  • Coryza (runny nose)
  • Diarrhoea
  • This typically lasts for 3-4 days
• Neurological symptoms being 3-4 days after the other symptoms and can include:
  • Headache
  • Irritability
  • Agitation
  • Confusion
  • Drowsiness
  • Coma
  • Parkinsonian featruesmay be present
    • Mask-like face
    • Pill-rolling tremor
    • Cogwheel rigidity
  • Dystonia
  • Rigidity
  • Other focal neurological symptoms
  • Seizures
    • Especially in children – up to 85% of patients, 10% of adults
    • Persistent seizures indicate raised intracranial pressure and is a marker for poor outcome
• Other symptoms
  • Hepatomegaly
  • Splenomegaly
  • Raised liver enzymes
  • Thrombocytopenia
• Symptoms of meningitis may also be present

Investigations

Testing for JEV can be difficult. PCR testing can be performed on various sample including CSF, blood, urine, serum – and confirms diagnosis if it is positive. However – viral load levels are often low and transient and this results in a high rate of fall negative results.

• PCR is not always useful
• Positive IgM in CSF is the gold standard diagnostic test
• IgG positive blood results may also be useful – but may not be positive initially

Also – other flaviviruses can cause false positives – such as Dengue, Murray Valley encephalitis and Kunjin. It may also be necessary to specifically test for these viruses to assess which is the true cause of a positive result.

Imaging

• MRI may show parenchymal inflammation – typically affecting the thalami, basal ganglia and brain stem
• This is not diagnostic for JE

Management

Any presentation suspicious for encephalitis and meningitis is a medical emergency. Initial treatment of these patients should involve:

• Basic resuscitation
• Empiric antibiotic therapy – check local guidelines for meningitis
  • E.g. Ceftriaxone 2g IV every 12 hours

There are no specific treatments for Japanese Encephalitis. Treatment is supportive and aimed at reducing the risk of neurological damage:

• Control seizures
• Manage raised intracranial pressure

Prevention

Prevention involves measure to avoid mosquito bites, as well as vaccination against Japanese Encephalitis in at risk groups.

Mosquito prevention measures include:

• Limiting time outdoors during peak mosquito activity (dawn and dusk)
• Wear long, loose fitting clothing
• Apply effective mosquito repellant (usually a DEET based product)
• Minimise locations where standing water can accumulate
• Use of fly screens and mosquito nets where appropriate

There are two Japanese Encephalitis vaccines available:

• Imojev – single dose, live attenuated vaccine. Not suitable for use in pregnancy, breastfeeding or if immunocompromised. No booster required.
• JEspect – inactivated virus – required a two dose schedule 28 days apart. Booster recommended at 1-2 years for those with ongoing risk

The following groups are recommended to be vaccinated

• Spending >1 month in endemic areas with activities that put them at risk of mosquito exposure
• Those working in laboratory environment with JEV
• Those who work in close proximity to pigs in endemic countries

References

• Japanese encephalitis clinical update: Changing diseases under a changing climate – AGJP – Volume 52, Issue 5, May 2023
• Japanese Encephalitis fact sheet – NSW Health
• Japanese Encephalitis – Better Health Channel

Read more about our sources

The post Japanese Encephalitis appeared first on almostadoctor.

Chickenpox is a common, highly infectious, usually self-limiting viral illness caused by the varicella zoster virus. Varicella is a type of herpes virus – and like other herpes viruses – after the virus has been contracted it may remain dormant in the host for many years – and can sometimes reactivate. In the case of varicella – reactivation of the virus causes the illness shingles.

Although chickenpox is usually mild, it can cause pneumonia (more properly a pneumonitis) and in those who are immunocompromised and in neonates it can cause a serious disseminated (widespread to many organs) illness.

It is possible to be infected (including developing immunity) and never develop the clinical syndrome of chickenpox.

The virus is typically airborne and enters the body through the respiratory tract. Viraemia (virus in the blood) can be detected 4-6 days later, but the first symptoms don’t usually occur until 10-14 days after exposure and it can be as long as 21 days. There may be a short prodromal period of a few days before the rash develops. The rash is quite characteristic and can usually be diagnosed clinically.

Usually, no specific treatment is required and most cases resolved within about a week of the onset of the rash. A patient is considered no longer infectious once all of the lesions of the rash have crusted over.

Neonates and those who are immunocompromised, as well we pregnant women who are not immune may receive specific treatment such as IV immunoglobulin or the antiviral medication aciclovir.

In recent years, vaccines against varicella have been developed. In Australia it is now routine to vaccinate children against chickenpox – this comes in combination with the MMR vaccine – the MMRV vaccine – and is given with he third dose of the MMR at age 18 months. A single dose of varicella vaccine is required. Shingles is a significant cause of morbidity in older populations and vaccination is hoped will reduce the incidence of shingles in future, as well as the incidence of chickenpox and the risks of chickenpox in pregnancy.

Epidemiology and Aetiology

Varicella can be passed on by either an active case of chickenpox or an active case of shingles – however chickenpox is much more infectious than singles. Varicella is endemic in most countries and tends to occur in outbreaks. The peak time of year is in spring.

• Over 90% of the population have contracted the illness by the age of 15 in endemic areas (this stat is from the UK)
• Less common in tropical and subtropical regions
• Infection tends to occur before the age of 10 in most developed countries. An older age is more common in warmer climates
• Patients are infectious from a few days before the lesions show, until all the lesions have crusted over. Some sources suggest this is from day 8-21 after exposure
• Is it not possible to “catch shingles. Shingles is a reactivation of the varicella virus in a host who has previously had chickenpox. However it is possible to catch chickenpox from someone who has shingles – however this is rare. Covering up the lesions of shingles reduces the risk.

Presentation

The rash of chickenpox has a specific pattern and the diagnosis can usually be made clinically on the basis of this rash.

• The rash occurs in “crops”
• Each crop consists of a handful of spots
• The first crop is typically on the head, neck or torso
• Further crops follow several hours (up to 12 hours) later
• Over the course of 24-72 hours the rash becomes widespread on most of the body – the limbs are usually less severely affected
• The lesions at first are discreet red raised lesions
• These becomes fluid fills blisters, before crusting over and drying out
• There are usually patches in different places not he body going through a different part of this process
• The patient is considered to no longer be infectious once all the lesions have crusted and dried
• Marks are often visible for several weeks, but only rarely does it cause long term scarring
• The rash may be itchy bit isn’t always
• Females may have painful vulval lesions
• secondary bacterial infection of the lesions can occur – this is also more common in eczema

Other symptoms include:

• Fever – may be for up to 4 days
• Headache, myalgias – these can start several days before the rash begins
• In those two have been previously immunised a very mild form of the disease may develop
• Pneumonia is a rare but serious complication

Diagnosis

• Diagnosis is almost always clinical
• Swabs of the fluid from blister can be sent for laboratory confirmation but this is not usually necessary

Management

Most cases in previously well individuals do not require specific management. Children aged >1 week and <12 years do generally not require any specific treatment. The illness can be more severe in teenagers and adults. Advice should be given about:

• Avoiding scratching
  • Antihistamines and emollients (moisturises) are effective to reduce the itch
  • Calamine lotion is NOT recommended as the effect ceases as soon as it dried (which is usually very quickly)
• Avoid pregnant women, neonates and those who may be immunocompromised until all the lesions have dried and crusted over
  • Patients should isolate from school / work until no longer infectious
• Encourage adequate fluid intake
• Paracetamol may be given for fever and headache
  • 15mg/Kg QID in children
  • 1g QID in adults
• Avoid the use of ibuprofen and other NSAIDS
  • These can increase the risk of group A strep (GAS) infection when given with varicella virus
  • Aspirin should be avoided in children due to increase risk of Reye syndrome
• Aciclovir should be considered in those who are immunocompromised, pregnant or have serious illness. You may also consider prescribing it in those who present in the first 24 hours as it may reduce disease severity
  • Not recommended in children unless systemically unwell or immunocompromised. Specialist advise should be sought
  • Patients whom are considered at higher risk include:
    • HIV, organ transplant, haematological malignancy, on chemotherapy
    • Systemic disease
    • On long term steroids or other immunosuppressants
    • New lesions are appearing more than 8 days after the first

Contacts

Contacts who are at high risk of disease (See risk factors above) should be considered for prophylactic management

• VZIG can be given cup to 10 days after exposure as long as no rash has developed. More effective the earlier it is given
• Those who are known to not be immune can be vaccinated after exposure but before symptoms develop
• Early treatment with aciclovir may also be considered

Complications

• Secondary skin infection
  • Occurs in up to 20% of cases
  • More likely in patients who scratch a lot!
• Secondary bacterial infections – particularly groups A streptococcus (GAS)
  • This is a serious illness that can cause necrotising fasciitis and toxic shock syndrome
• Viral pneumonia
  • Can be fatal (very rare)
  • More common in older children and adults
  • Symptoms usually start within 4 days of onset of the rash
• Encephalitis

Varicella in pregnancy

Contracting varicella for the first time in pregnancy can cause serious and life-changing consequences. Varicella if contracted in the first 20 weeks of pregnancy can cause fetal varicella syndrome (FVS) – which can result in birth defects – of the skin, eyes, brain and gastrointestinal tract.

• This occurs in <1% of cases

Later in pregnancy there is a higher risk of stillbirth. Mothers than contact varicella in the last 4 weeks before birth can also pass on the virus to the child which can lead to the potentially life-threatening neonatal varicella. Varicella in pregnancy may also cause a serious illness in the mother – and can cause complications such as pneumonia.

• Primary varicella infection affects 3 in 1000 pregnancies in the UK
• Women from tropical and subtropical areas are at greater risk due to the reduced immunity in these areas

In Australia – all. mothers are screened for varicella immunity at the start of pregnancy. In the UK this is not routine but may be offered if there is no known previous history of infection or vaccination. If it is found that the mother is not immune:

• She should be advised about the risks of varicella in pregnancy and to avoid contact with anyone known to have chickenpox or shingles
• She should be advised to inform a healthcare worker immediately if she is known to be exposed to varicella
• She should be offered vaccination in the post-natal period (after the birth). Vaccination is not usually recommended during pregnancy. It is safe to breast-feed after vaccination

RCOG guidelines suggest the following for managing exposure and infection during pregnancy:

• Women with a known high risk exposure should be offered intravenous immunoglobulin (IV VZIG). This is effective for up to 10 days after exposure.
  • Note that if you receive VZIG then you are potentially infectious for longer than if you don’t (form 8-28 days after exposure as opposed to 8-21 days in people who don’t receive it
  • A second dose may be required if there is another exposure and more than 3 weeks has passed since the first dose was given
• Women who develop a rash need to be isolated form other pregnant women – this can have implications for their antenatal care
• Oral aciclovir can be given to women who develop a chickenpox rash
  • Before 20 weeks this is associated with teratogenic effects (but risk is probably lower than chickenpox risks)
  • After 20 weeks generally considered safe and should be offered to all women after this gestation
  • Course is usually 1 week long
• IV aciclovir should be given to all women with serious symptoms
• VZIG is of no benefit once the rash has developed and should not be given

References

• Chickenpox (varicella) – RCH
• Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
• Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy
• Chickenpox in pregnancy – RCOG
• NSW Health – Immunisation schedule – accessed on 25/06/2023
• NHS vaccines and when to have them
• Chickenpox vaccine – NHS

Read more about our sources

The post Chickenpox (varicella zoster) appeared first on almostadoctor.

The influenza vaccine is an annual vaccine, typically offered to patients at high risk of seasonal influenza (flu). It is not usually a live vaccine. Modern vaccines typically contain constituents of 4 strains of influenza. The exact strains included in vaccine formulations is decided up based on the previous years strains, and emerging strains noted around the globe.

Typically the vaccine is about 50-60% effective – meaning that of the people who receive the vaccine, the chances of contracting the flu in any given year are halved. This varies from year to year depending on the exact strains circulating and in the vaccine. It is thought that a small amount of immunity is conferred for subsequent years.

Efficacy is typically greatest in the first 3 months, and then starts to wane. In some very high risk groups (e.g. cancer patients), a second dose may be advisable later in the flu season. For most people this isn’t required.

It is typically recommended for everyone aged over 6 months, although in most developed countries, it is only “free” (government funded) for certain high risk groups. Other individuals may choose to pay for the own vaccine, and many employers choose to offer the vaccine to their workers to reduce the number of sick days over the winter.

Patients aged over 65 should received a ‘high dose’ vaccine, as in this age group, the immune response is less effective and a stronger dose is required to induce immunity.

There are several preparations available, and the exact brands and specifications change from year to year. There is a nasal spray variation available int he UK which is typically the type given to children.

Who should be vaccinated?

High risk groups are generally defined as:

• Anyone aged over 65
• Pregnant women – the vaccine can be given at any time during pregnancy
• Anyone aged >6 months with a chronic illness – e.g. COPD, asthma, cardiovascular disease, diabetes, cancer, hepatitis B or C, HIV or any other long-term illness requiring ongoing medical care
• Health care or social care workers
• Those caring for a vulnerable relative at home
• Children (NHS recommends primary school aged children, Australia recommends all children aged 6 months to 5 years)
• In Australia – patients of Aboriginal or Torres Straight Islander background aged >15

Contraindications

• Anaphylaxis to previous influenza vaccine or component of influenza vaccine * (see egg below – special case)
• First episode of Guillain-Barre Syndrome within 6 weeks of an influenza vaccine
• Currently febrile / unwell

Immunosuppressants are not a contra-indication

• Taking specific immuno-oncological agents may be a contra-indication. These are; Ipilimumab, Nivolumab, Pemrolizumab – some sources suggest patients should NOT receive the HIGH DOSE (>65 versions) of the flu vaccine, but that the normal dose may not cause adverse effects. I would discuss with specialist (oncologist +/- infectious diseases) before giving the vaccine to anyone taking these drugs

Egg allergy

• Allergy, including anaphylaxis is no-longer a true contraindication
• Those with previous allergy to egg can safely be given full dose
• Those with previous anaphylaxis to egg can be safely given full dose – but recommended to be given in an environment where they can be safely monitored and treated for anaphylaxis

Questions to ask the patient

1. Have you ever received a flu vaccine before?
2. Have you ever experienced any problems after receiving a flu vaccine in the past?
3. Are you allergic to eggs or egg products?
4. Have you had any severe allergies in the past?
5. Do you have a fever or are you currently unwell?
6. Do you have a history of Guillain-Barre Syndrome?
7. What medications are you currently taking?

Potential side effects

• Soreness at injection site – typically lasts for several days
• Fever / flu like symptoms (malaise, myalgias)– usually for <48 hours
• Doesn’t guarantee protection fro the flu – estimated efficacy is 50-60% in those aged <65

References

• Influenza (flu) – Australian Immunisation Handbook
• Who should have the flu vaccine – NHS
• Seasonal Flu Vaccine – NSW Health
• Annual Seasonal Influenza Vaccine – ACT Health

Read more about our sources

The post Influenza Vaccine appeared first on almostadoctor.

Rheumatic fever was a common infectious disease until around the middle of the 20th century, and was a major cause of childhood mortality and rheumatic (structural) heart disease.

In developed countries, the incidence rapidly declined during the second half of the 20th century, however it remains a common and important disease in developing countries and amongst indigenous populations, particularly in Australia, New Zealand, the Pacific Island nations, and to a lesser extent in South America.

• The decline in incidence is believed to be multifactorial, due to the advent of penicillin, a decline in virulence in the strains of streptococci that cause the infection, and improved living conditions

It is the result of infection with Group-A beta-haemolytic streptococcus (GpA BHS). These infections are typically pharyngitis or tonsillitis, and less commonly scarlet fever or skin infections.

Rheumatic fever typically begins several weeks after the initial infection – which has often resolved by this point. It is thought that antibodies produced to streptococcal proteins begin to react against cardiac and other tissues.

As well as acute rheumatic fever, there is also a recurrent from of the illness – with episodes of fever months or years after the initial infection (thought to be due to re-infection). About 50% of patients will go on to develop rheumatic heart disease in the long term – the risk is higher in those who have recurrent episodes of fever.

It it not only the heart that is affected, but also skin, joints and nervous system.

You should suspect a diagnosis of rheumatic fever in any patient who presents with chorea (neurological signs) or carditis, without another identifiable cause.

Diagnosis is based on the Jones Criteria.

Management aims to control the symptoms of the arthritis, skin manifestations and chorea, but it is the carditis that is the most serious manifestation of rheumatic fever. It can lead to heart failure, and in some cases, can be fatal in the acute phase.

• Acute rheumatic fever has a mortality of about 1.5% in the developed world.
• It is usually recommended that patient start on prophylactic antibiotics to prevent a recurrent infection
• No treatment has been proven to reduce the risk of progression from rheumatic fever to rheumatic heart disease

In the long-term, any patient who has had previous rheumatic fever, is at almost 50% risk of rheumatic heart disease. This typically manifests as mitral value disease, although other valves can be affected.

Epidemiology

• High incidence in areas of overcrowding and poor access to healthcare
• Higher incidence in winter
• Typically affects school age children
  • Median age 10.4
  • Rare before age 3 and after age 21
• In developed countries, incidence is <1 in 100 000
• In indigenous populations in Australia, the incidence is about 375 per 100 000
  • 60% of patients will go on to develop heart disease

Aetiology

• Poverty
• Overcrowding
• Family history / genetic factors

Pathology

The exact pathology is not well understood. It is caused by Group A beta-haemolytic streptococci, of which there are many types. Those with the M antigen are most likely to cause Rheumatic Fever.

• It is thought that the organ damage caused in the disease is actually a result of a type hypersensitivity reaction – the damage is caused by cross-reacting antibodies – and not by the bacteria itself
  • The antibodies for streptoccoal M protein also act against cardiac myosin
• Heart valves are infiltrated by T cells – which are reacting against cardiac myosin, having been activated against the M antigen
• It is believed there is also a genetic susceptibility, as there is great variation in disease in those infected with similar strains
• In acute rheumatic heart disease, the mitral valve is most commonly affected, although often all 4 valves can be affected.

Presentation

• Symptoms typically occur 1-5 weeks after an infection (e.g. after a sore throat)
  • In recurrent cases, this period is often shorter due to a quicker immune response
• Symptoms include:
  • Fever
    • Typically for about 1 week
  • Arthritis
    • The pain is often very severe, and if the lower limbs are affected, patients may be unable to walk
    • Usually asymmetrical, polyarthritis
  • Neurological signs of symptoms (30% of patients)
    • Syndenham’s chorea – rapid purposeless movements, especially of the face and upper limbs
    • Tourrette’s syndromes
    • Often cease during sleep
  • Skin signs and symptoms
    • Subcutaenous nodules (10% of patients)
    • Erythema marginatum / erythema annulare
      • Different names for the same rash
      • Rash with macule or paupules of 1-3cm on the trunk and arms
      • Face is spared

• • Cardiac signs and symptoms (40% of patients)
    • Aortic regurgitation –Austin Flint’s murmur
    • Carey Coombs’ sign refers to a characteristic soft diastolic murmur due to mitral valve invovlement
    • Pericardial rub
    • Tachycardia
    • Endocarditis and Myocarditis
    • Signs on echo include:
      • Mitral valve changes in 70% of patients
      • Aortic vale – 25%
      • Tricuspid – 10%
      • Pulmonary – rare

The Jones Criteria

Diagnosis is based on the Jones Criteria. For diagnoses, the following are required:

• Evidence of recent streptococcal infection
  • e.g. scarlet fever, or a positive throat or wound swab, or serologically confirmed streptococcal infection – e.g. with a raised anti-streptolysin O titre (ASOT) of >200U/ml
• PLUS two major criteria, OR one major and two minor criteria

Major Criteria

• Arthritis
• Sings of carditis (murmur, echo signs)
• Chorea
• Subcutaneous nodules
• Erythema marginatum / annulare

Minor Criteria

• Fever
• Raised CRP or ESR
• Arthralgia
  • Can’t be used in conjunction with arthritis as a major sign
• Prolonged PR interval
  • Cant be used in conjunction with carditis as a major sign

Even when the diagnostic criteria are not met consider rheumatic fever is any patient with chorea or carditis without an obvious cause. 

Differential Diagnosis

• Arthritis
  • Rheumatoid arthritis
  • Henoch-Schonlein purpura
  • Reactive arthritis
  • Erythema nodosum
• Cardiac causes
  • Infective endocarditis
  • Cardiomyopathy
  • Myocarditis (other causes)
• Neurological signs
  • Drug reactions – e.g. dystopias related to metoclopamide

Investigations

Throat swab

• Frequently performed – but often the acute infection is long gone by the time the diagnosis has become apparent

Blood tests

• Anti-streptolysin antibody titre (ASOT)
  • Levels >200 suggest a diagnosis of rheumatic fever
• anti-DNase B
• Antibody levels usually rise for the first month of the illness and remain stable for the following 3-6 months

ECG

• Prolonged PR interval

CXR

• Signs of heart failure

Echocardiography

• To detect signs of carditis
• Can result in earlier diagnosis – signs of carditis may be apparent on echo before the other symptoms develop

Management

Aims

• Treat any streptococcal infection that is still present
• Reduced inflammation related to the immune response
• Treat complications – especially carditis
  • Neurological, arthritic, and skin symptoms are often self-limiting. The cardiac complications can be life-threatening

Treating infection

• Penicillin is the treatment of choice against streptococcus
  • Guidelines vary. Both oral and intramuscular preparations are recommended. Intramuscular injections are slow-releasing and long-acting and prevent issues related to compliance with an oral regimen
  • Cephalosporins or erythromycin are suitable alternatives in penicillin allergy

Treating complications

• Aspirin or other NSAIDs are effective for arthritis
  • High doses are often required
  • Not proven to reduce carditis (but theoretically could)
• Cardiac complications
  • Treat heart failure as you would for any other patient – e.g. with ACE inhibitors, digoxin, and diuretics if required
  • Mitral valve replace may be required
• Neruological complications
  • Chorea is typically self-limiting. Diazepam can reduce symptoms in the short term

Prognosis

• 80% of patients will recover from an acute episode of rheumatic fever within 12 weeks
• Recurrent episode of rheumatic fever can occur – usually, but not always associated with re-infection with streptococcus
  • If these episodes do occur, it is usually within 5 years of the original diagnosis
• Rheumatic heart disease occurs in up to 45% of patients in the long-term
  • Patients need life-long cardiology follow-up
• Recurrent episodes can be triggered by repeat streptococcal infection, pregnancy, or use of the COC pill

Prophylaxis

• Secondary prophylaxis (long-term antibiotic use) is recommended for all patients
• Should be continued for a minimum of 5 years, or until the age of 21 – whichever is longest
• Recommended 10 years for patients with carditis
• In patients with severe valvular disease, life-long prophylaxis may be recommended

Flashcard

References

• Rheumatic fever – patient.info
• Rheumatic fever – BMJ Best Practice
• Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
• Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.

Read more about our sources

The post Rheumatic Fever appeared first on almostadoctor.

Q fever is an infectious disease usually acquired from working in close quarters with live animals. It is caused by the Gram-negative bacterium Coxiella burnetii. 

It was named “q” (for query) fever in 1937 in Queensland, Australia, and the infective organism was subsequently simultaneously identified in the US and Australia. It has now been identified almost world-wide, except in New Zealand and Antarctica.

Due to non-specific symptoms is often difficult to diagnose. It is widespread in the animal kingdom, but found mainly in cattle, sheep and goats, although almost any wild animal can be infected. It is most commonly transmitted to humans through inhalation.

It causes both an acute and chronic illness, but is thought to be widely under-diagnosed in the acute phase. The chronic disease occurs in <5% of cases, but can be fatal.

A vaccine exists, although the practicalities of immunisation can be somewhat tricky.

Epidemiology

• Thought to be vastly under-diagnosed due to the asymptomatic nature of the majority of presentations
• Most common in Australia – about 2.5 cases per 100 000 per year
  • 6 per 100 000 in QLD
  • 3 per 100 000 in NSW
  • Rare in other parts of Australia
• In Europe and the USA, there are about 0.1 cases per 100 000 per year
  • One study in the UK showed that about 21% of dairy herds were infected
  • Animals rarely become ill, but do show increased rate of abortion and stillbirth when infected
• There are times of outbreak. The largest outbreak recorded was in the Netherlands in 2010, when 4,000 cases were reported
• Most commonly affects middle aged males (likely due to this demographic being most likely to work with livestock or in slaughterhouses)

Transmission

Coxiella burnetti bacteria are shed in most bodily fluids, but particularly in birth products. As such, it may be easily widely spread in the environment in manure. It can also be found living in dust and soil, where it may survive for many months or even years.

It is most commonly transmitted to humans through inhalation of dust or contaminated other aerosols.

• It can also be contracted by drinking raw milk
• It can also be transmitted through cuts from infected sharp objects, or needle stick injuries from animals
• It may also be transmitted from human to human via sexual transmission, vertical transmission, blood products and autopsy of infected cadavers

It has an incubation period of 2-3 weeks, sometimes up to 6 weeks.

Presentation

• 60% of cases are asymptomatic
• Infection typically provides lifelong immunity

Acute infection

• Flu-like symptoms
  • Fevers – can last up to 10 days
  • Myalgia
  • Headache
  • Nausea
  • Cough
  • Rash – maculopapular
• Hepatitis
• Pneumonia
  • More commonly an atypical type
• Rarely
  • Myocarditis
  • Pericarditis
  • Neurological complications
• Mortality in acute Q fever <2%

Chronic infection

• Anywhere from one month to several years after primary infection
• Fever
• Hepatomegaly and splenomegaly (50%)
• Clubbing
• Abdominal pain
• Chest pain
• Night sweats
• Endocarditis
  • Occurs in about 2% of patients
  • Fatal if untreated
  • If treated, 10 year mortality is about 20%
• Bone and joint infections
  • <1% of cases
  • Common when Q fever occurs in children (although children are rarely infected)
• Vascular infections
  • Especially at sites of previous aneurysm or graft
  • Mortality rates of about 20-25%

Q fever fatigue syndrome

QFS affects about 10-15% of patients. It is a chronic syndrome that occurs after acute infection, and includes on-specific fatigue type symptoms such as:

• Lethargy
• Fatigue
• Myalgia
• Arthralgia
• Sleep disturbance
• Memory issues

Diagnosis

• Requires a level of clinical suspicion to be considered as a differential
• Culture for coxiella burnetti should be avoided
  • It is difficult to culture
  • When it is successfully cultured it is a high risk for laboratory technicians
  • When requesting a blood culture and Q fever is a differential this should be clearly states on the referral form
• Q fever serology or Q fever PCR are the preferred methods of testing
  • These are usually both performed in conjunction with one-another
  • PCR results are quick, but less accurate
  • Serology testing often requires x2 samples, 7 days apart to confirm the diagnosis
    • Seroconversion takes up to 3 weeks after symptom onset
  • PCR can be done on a single sample but has a higher false negative rate
  • Consider consulting an infectious diseases specialist for advice on diagnosis if Q fever is suspected
• FBC usually raised
• CRP usually raised
• LFTs may be elevated
• Transoesophageal echo should be considered in all patients thought to be suffering from chronic Q fever
• CXR – if any evidence of pneumonia

Management

• Docycline 100mg BD for 14 days is the recommended treatment
• Refer to infectious diseases specialist
• Chronic Q fever
  • Requires long-term antibiotics – often 18 months or more
    • Taking doxycycline for this long is unpleasant. It frequently causes oesophagi’s and may also cause photosensitivity. Patients should avoid air products within 2 hours of taking doxycycline.
  • Involve infectious diseases specialist as soon as possible
  • If any prosthetic implants (e.g. prosthetic heart valves, aneurysm repairs) or if immunocompromised, MDT specialist care should be sought as soon as possible
  • Measure antibody titres every 6 months

Vaccination

Q fever vaccine (Q-Vax(R)) has been available since 1989. Efficacy 83-100%.

The vaccine is recommended to anyone at risk of Q fever – including anyone who works with live animals or untreated raw animal products.

• Hypersensitivity reaction can occur if the vaccine is given to anybody who has previously been infected with Q fever or had previous vaccination
• As such, pre-vaccination testing is required for anybody wishing to be vaccinated. This usually includes:
  • Detailed history and review of medical records for any previous vaccinations or diagnoses
  • Skin testing for cellular immunity
    • Similar to the TB skin test
    • Skin (scratch) and serological testing done on the same day
    • Patient need to return 7 days alter to have the skin lesion examined for signs of reactivity
  • Serological testing
    • Both skin and serological testing should be used together
• Not recommended for those <15 or during pregnancy
• Once skin and serological testing confirms no previous infection or vaccination, then a single dose of the vaccine is all that is needed.

Bioterrorism

Q fever is considered important as a potential bioterrorism agent. It is very stable in the natural environment, highly infectious and an aerosol agent, could easily be produced in large quantities and can cause serious disease.

References

• Q fever – patent.info
• Q fever – CDNA
• Q fever: a rural disease with potential urban consequences
• Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
• Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.

Read more about our sources

The post Q fever appeared first on almostadoctor.

Barmah Forest Virus causes infection in humans and other mammals. In humans, the infection results in polyarthritis, fever, tiredness, lethargy and rash. It has been identified only in Australia, and is named after the location in Victoria where it was first discovered in 1974.

It is clinically similar to Ross River Fever, but the symptoms tend to be less severe and of a shorter duration. Some patients, especially children, may be asymptomatic.

It is self-limiting, and treatment is usually supportive only. Most people recover within a few days, but in some cases, joint and muscle pain persists for up to 6 months.

It is most commonly seen in summer and autumn.

There are about 400 reported cases per year although the true prevalence is likely to be much greater. The short duration of illness, and asymptomatic nature means that many cases will go unreported. Over 50% of cases occur in Queensland.

Presentation

• Incubation period is about 3-11 days
• Polyarthritis – including joint pain and swelling
• Fevers
• Rash
• Headaches
• Tiredness
• Lethargy

Most cases last only a few days and patients are fit to return to work within a week.

Transmission

• Mosquito bites only
• Cannot spread directly from person to person
• Spread by multiple mosquito species
• Main reservoir of disease is in animals
  • Mainly kangaroos and wallabies, but up to 30 species are implicated
• Be wary of mosquito breeding grounds in standing water – e.g. salt marshes, mangroves, and in standing water around the house – such as bird baths, plant pots and in buckets and containers around the house
• Mainly occurs in tropical areas in Queensland and the Northern Territory, but also frequently reports in NSW and Western Australia
• Much more common in rural areas

Diagnosis

• Confirmed with serological testing

Management

• No specific treatment
• Simple analgesia
• Gentle exercise may help to relieve joint pains
• Chronic fatigue occurs in a small minority of cases

Prevention

• Avoid getting bitten by mosquitos!
  • Most bites occur in the early evening in warmer months
  • Use insect repellents
  • Wear light coloured clothing
  • Use fly screens on windows and doors
  • Check around the home for potential mosquito breeding areas
• Controlling mosquito breeding areas by local councils is effective at controlling outbreaks

References

• Barmah Forest Virus – Queensland Government
• Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt

Read more about our sources

The post Barmah Forest Virus appeared first on almostadoctor.

Ross River virus is a virus that causes an infectious disease known as Ross River Fever (aka endemic polyarthritis). It is spread by mosquitos, seen throughout Australia, most commonly in Queensland, as well as Papua New Guinea and other islands in the pacific.

Ross River fever is a debilitating but rarely dangerous illness, characterised by polyarthritis (95%), rash (50%), and tiredness or lethargy.

It can occur at any time of year in most of Australia, but most cases occur between February and May.

Diagnosis is confirmed with serology. There is no specific treatment, and symptom management is all that is required. Symptoms may persist for many months, and a post infective chronic fatigue (similar to EBV or CMV) is seen in about 10% of cases.

It is clinically similar to Barmah Forest Virus, although Ross River Fever typically is a more debilitating and longer lasting illness.

In indigenous it is important to consider a diagnosis of Rheumatic fever in patients presenting with fevers and polymyalgia.

Presentation

• Incubation period 3-11 days
• Arthralgia – 95%
  • Can be severe
  • Typical duration is 6-12 weeks
  • In most cases it has resolved by 7 months
• Rash – 50%
  • Between 1-10 days after the onset of joint pains
  • Mainly trunk and limbs
  • Rash lasts up to 10 days, usually less
• Fever
  • Often comes with the rash
• Chronic fatigue is present in about 10% of cases at one year after symptom onset

Diagnosis

• Confirmed with serological testing
• IgM is present 7 days after infection and remains positive for months or years

Transmission

• Mosquito bites only
• Cannot spread directly from person to person
• Spread by multiple mosquito species
• Main reservoir of disease is in animals
  • Mainly kangaroos and wallabies, but up to 30 species are implicated
• Be wary of mosquito breeding grounds in standing water – e.g. salt marshes, mangroves, and in standing water around the house – such as bird baths, plant pots and in buckets and containers around the house
• Mainly occurs in tropical areas in Queensland and the Northern Territory, but also frequently reports in NSW and Western Australia
• Much more common in rural areas

Prevention

• Avoid getting bitten by mosquitos!
  • Most bites occur in the early evening in warmer months
  • Use insect repellents
  • Wear light coloured clothing
  • Use fly screens on windows and doors
  • Check around the home for potential mosquito breeding areas
• Controlling mosquito breeding areas by local councils is effective at controlling outbreaks

References

• Ross River Virus – Queensland Government
• Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt

Read more about our sources

The post Ross River Virus appeared first on almostadoctor.

Strongyloides is a type of threadworm that commonly infections humans and other mammals.

• It is much less common in developed countries than another type of threadworm – pinworms. Colloquially, “threadworm” usually refers to pinworms.
• The word “threadworm” derives from the appearance of worm – which often look like small white “threads” (of cotton)

The main human worm strongyloides stercoralis is widespread in tropical areas. It rare in countries where there is not faecal contamination of groundwater, and thus is rarely seen in the developed world. It in endemic in parts of the far east, (Vietnam, Cambodia, Laos – up to 10% of the population), commonly seen in South America, and also widespread in Africa (<1% of the population).

In Australia, it is commonly seen in rural and remote Aboriginal communities living in tropical areas.

It lives in the intestinal mucosa, and is transmitted via contaminated feral matter.Infection is lifelong without treatment. It causes abdominal pain and watery diarrhoea, although many patients may be asymptomatic for prolonged periods.

Avoiding use of unclean bedsheets when travelling to endemic areas, and also the use of plastic slippers whilst showering in endemic areas may help to reduce transmission.

In cases of disseminated strongyloidiasis, it can be life-threatening – and there are reports of patients with disseminated disease given corticosteroids that precipitated death (hyperinfective syndrome).

It causes an eosinophilia in the FBC – beware of giving steroids to anyone who has been to an endemic area and has an eosinophilia.

Treatment is with ivermectin or albendazole – but regimens can be complicated and it is advisable to seek specialist infectious diseases help.

Epidemiology and Aetiology

• Worldwide, up to 370 million people are affected
• In some rural and remote aboriginal communities in Australia, up to 60% of the population are infected
• Immunosuppressed patients are at particular risk of potentially life threatening disseminated disease

Life cycle

• Microscopic larvae (“filariform” larvae) penetrate the skin and enter the bloodstream
• They travel to the heart, and into the pulmonary circulation
• They then exit the circulation in the lung and climb up the trachea, to be swallowed into the gastrointestinal tract
• In the intestine, mature adult females – approx 2-3mm long – penetrate the mucosa and lay up to 40 eggs per day
  • Females can reproduce without a male!
• The larvae then penetrate the mucosal surface and enter the intestinal tract, where they are shed in the faeces
• Many of these larvae then “auto infect” the original host by penetrating the colonic mucosa or perianal skin
• Larvae can survive in soil for several weeks

Strongyloides is particularly difficult to treat due to its autoinfective nature. In severe cases, there are many millions of larvae in various parts of the lifecycle migrating through many internal organs.

Stages of infection can be divided into:

• Acute
  • May cause acute onset gastrointestinal symptoms
• Chronic
  • May be asymptomatic, or non-specific intermittent symptoms
• Disseminated
  • High fatality rate
  • Can pre-dispose to sepsis and multiple end organ failure

Signs & Symptoms

• Larva currens – visible tract marks on the skin – often seen on the abdomen and buttocks – represents the larvae migrating in the skin. Move at about 2-10cm per hour
• Respiratory – pneumonia, lung abscess, haemoptysis, SOB
• Abdominal – abdominal pain, diarrhoea, malnutrition, epigastric pain
• Abscess of internal organs – e.g. renal, hepatic, brain
• Eosinophilia
• Sepsis – gram negative sepsis may occur due to bacteria carried by the larvae being introduced into the bloodstream

Diagnosis

• Strongyloides serology – highly sensitive and specific
  • May be falsely negative in acute cases which have not yet seroconverted
• Faecal examination – may be negative in early or minor infection

Management

• All cases, even those discovered incidentally which are asymptomatic should be treated to avoid progression to potentially fatal disseminated disease
• Difficult to treat – a single remaining parasite can cause re-infection
• Ivermectin is the treatment of choice
• Albendazole is second line – it is also less effective and although reduces severity of infection may not be curative
• Follow-up is required to ensure eradication
  • At 6 months
  • Consider bloods for eosinophilia as well as serology and faecal examination
  • Eosinophilia may be the only sign of recurrence
  • Disease is considered eradicated if serology and faeces are negative and there are no ongoing symptoms

References

• Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
• Strongyloides – RACGP

Read more about our sources

The post Strongyloides appeared first on almostadoctor.

Cellulitis is caused by bacterial infection of the dermis layer of the skin and the deeper subcutaneous tissues. Often the infection is due to a break or puncture to the skin which allows bacteria to enter, however in some cases no obvious break to skin integrity can be located.

The most common sites for cellulitis to occur are the legs and face, although cellulitis can cause infection to any area of skin. Typically the presentation is of unilateral leg symptoms following a break to the skin.

Cellulitis infections are often minor requiring primary care management, however in elderly patients or those with significant co-morbidities, cellulitis can be of great morbidity and mortality.

Epidemiology

Very common infection presenting to primary, secondary and emergency care

Incidence of 24.6/1000

Risk Factors

• Wounds to the skin
• Diabetes
• Old age
• Insect bites
• Obesity
• Fungal infections between toes
• Skin conditions such as eczema
• Chronically swollen legs (e.g. lymphoedema)
• Chronic venous insufficiency
• Varicose veins
• Intravenous drug user
• Immunosuppression
• Previous cellulitis

Aetiology

Most common causative organisms are:

• Group A beta-haemolytic streptococci – Streptococcus pyogenes
• Staphylococcus aureus

Less commonly:

• Streptococcus pneumonia
• Haemophilus influenza – Often in infants prior to Hib vaccination
• Gram negative bacilli
• Anaerobes

Symptoms

• Often in the lower limbs, effecting one leg
• Symptoms spread quickly
• Erythema (rubor) – blends into surrounding skin. “Tracking” can occur along blood vessels and tends to spread more quickly than generalised erythema
• Pain (dolor)
• Swelling (tumor)
• Warmth of effected skin (calor)
• Often a site of skin damage – ulcer, wound, bite mark, injection site
• Systemic effects – fever, malaise, nausea, rigors, confusion in the elderly

Differentials

• DVT
• Varicose eczema
• Ruptured Baker’s cyst
• Necrotizing fasciitis
• Metastatic cancer (carcinoma erysipeloides)

Investigations

Primary Care

Not usually required

Diagnosis can be made on clinical history and examination alone

If there is an obvious wound in the skin with discharge then this may be swabbed

Secondary Care

Bloods – Raised WCC, CRP, fasting glucose, lipids, cholesterol

Blood cultures  – Identify the causative organism and direct antibiotic choice

X-ray, CT, MRI – If concerns of deeper infection and/or foreign body in situ

Treatment

General considerations:

• Analgesia
• Elevate legs
• Requirement for Tetanus vaccination

Send to hospital if:

• Significantly unwell with symptoms such as tachycardia, tachypnoea, hypotension, vomiting, or acute confusion
• Unstable co-morbidities such as uncontrolled diabetes
• Contaminated wound
• Limb threatening infection due to vascular compromise
• Sepsis or life threatening complications such as necrotizing fasciitis
• Very young (<1 years) or frail
• Immunocompromised
• Gross limb swelling
• Facial cellulitis
• Periorbital cellulitis

If minor/mild cellulitis and is being treated by GP:

PO Flucloxacillin 500mg QDS for 7 days

Or if penicillin allergic

PO Erythromycin 500 QDS or Clarithromycin 500 mg BD for 7 days

For cases requiring management in hospital:

Flucloxacillin 1 gram QDS IV (For 48 hours, then r/v if can be stepped down to oral)

Or if penicillin allergic

Clindamycin 600mg QDS IV (For 48 hours, then r/v if can be stepped down to oral)

If case may have been contaminated by fresh or salt water consult microbiology

Complications

Acute

• Abscess formation
• Sepsis
• Myositis / Osteomyelitis
• Necrotizing fasciitis – consider if pain is not being eased by analgesia!!
• If around the eye can spread to cause meningitis
• Post streptococcal nephritis

Chronic

• Persistent leg ulceration
• Chronic lymphoedema

Prognosis

Vast majority of patients will make a complete and uncomplicated recovery

Recurrence rates of cellulitis have been reported between 11-16%

References

• Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
• Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
• Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy

Read more about our sources

The post Cellulitis appeared first on almostadoctor.

The post Summary of Types of Bacteria appeared first on almostadoctor.