CDC

Question 1

Syphilis

Answer 1

Key memory points:

• incubation period 10-90 days; median 3 weeks
• diagnosis requires treponemal specific test (IgG, TPHA, TPP) and a non-treponemal test (RPR or VDRL); RPR must be monitored to determine response to treatment.
• contract tracing: duration of symptoms + 3months for primary, symptoms + 6 months for secondary; 12 months for early latent and probable infectious.
• no sex for 5 days after IM benzathine penicillin administered.

Disease characteristics:
- caused by treponema pallidum, obligate human parasite
- transmitted by direct skin to skin contact with infected lesions or mucous membranes
- incubation period 10-90 days, with median of 3 weeks
- most infectious in first 12 months with high risk of vertical transmission; considered non-infectious after 2 years but risk of vertical transmission remains.
- primary syphilis: 10-90 days; chancre; regional lymphadenopathy; may have atypical presentations
- secondary syphilis: 4 - 10 weeks; headache, fatigue, lymphadenopathy, low grade fever, sore throat, rash, mucocutaneous lesions, condylomata lata (large, raised, whitish or grey, flat-topped lesions found in warm moist areas) and alopecia. Ocular and neurological symptoms may also occur. Secondary syphilis may commence prior to the resolution of the primary lesion. Untreated secondary syphilis symptoms persist for 3-12 weeks after which the patient enters the early latent phase. Symptomatic relapses of secondary syphilis occur in 25% of untreated cases, mainly in the first 12 months after infection.
- early latent syphilis: syphilis of less than 2 years duration in a person who has no signs or symptoms at the time of diagnosis
- late latent syphilis: syphilis of more than 2 years duration.
- tertiary syphilis: between one quarter and one third of infected and untreated individuals will ultimately develop tertiary syphilis. Bone and skin lesions at any time after 2 years but usually
between 2 and 15 years, cardiovascular disease at 20-30 years and three types of central nervous
system disease (meningo-vascular at 5-12 years, and general paresis and tabes dorsalis usually at 15-25 years).
- congenital syphilis can result in intrauterine foetal death, stillbirth or a premature baby with congenital syphilis. In early congenital syphilis, the infected baby may be severely affected at birth (with hepatomegaly, ascites, hydrops, foetal anaemia) or more frequently, may not present any observable sign. If the diagnosis is not made then, the baby will present later with non-specific complaints (rhinitis, failure to thrive, pneumonia), nearly always within three months of birth. Neonates with severe disease have a worse prognosis.

Diagnosis:
- diagnosis requires both a treponema-specific test and a non-specific test.

Case management:

• infectious cases in pregnant female are of urgent priority; other infectious cases are high priority; non-infectious cases are routine priority
• consider carefully who should interview the case and in what setting this should occur.
• confirm onset date and symptomatology; obtain full sexual history; ensure tested for other STIs
• treat ASAP; infectious syphilis can be treated with a single dose of IM benzathine penicillin 1.8 mg; syphilis of >2 years or unknown duration requires three IM injections over 3/52
• At the time of the first treatment dose, blood should be collected for non-treponemal tests RPR (rapid plasma regain) or Venereal Disease Research Laboratory (VDRL) to provide the baseline used to assess response to treatment and check for re-infection. RPR testing, ideally by the same laboratory that undertook the baseline assessment, at 3-6 months and at 12 months after treatment.
• cases become non-infectious 5 days after treatment.
• Cases education: no sex for 5 days after treatment, counsel on risk of reinfection, counsel on need for follow-up testing at 3-6 months and at 12 months.

Contact management:

• Look-back period depends on the stage of syphilis for the case: duration of symptoms plus 3 months for primary, duration of symptoms for 6 months for secondary, 12 months for probable infectious and latent.
• Can be contacted via patient or provider referral: provider referral usually employed in remote communities.
• Contacts should have syphilis serology and testing for other STIs, and lesions should be swabbed for PCR and empiric treatment should be administered regardless of serology results.

Other relevant info:

• national syphilis outbreak amongst MSM
• multijurisdictional outbreak amongst First Nations people in certain rural and remote areas of QLD/NT/WA/SA; majority of cases in 15-29 year olds.
• MJSO working group (MJSO) formed under CDNA in 2015
• WA/SA/NT/QLD have syphilis registers
• The Australian Government has committed $21.2 million over four years (2017-18 to 2020-21) to fund an augmented health workforce and point-of-care testing in targeted Aboriginal Community Controlled Health Services (ACCHS) within the affected outbreak regions. The funding also includes the development and dissemination of a multi-strategy Aboriginal and Torres Strait Islander community awareness, education and testing campaign for syphilis and other STI/BBV. For further information, please refer to Community Engagement and Health Resources section of this page.

Question 2

Hepatitis A

Answer 2

Key memory points:

• incubation period 15-50 days
• infectious period 14 days prior to prodrome onset to 14 days after prodrome onset or 7 days after jaundice onset.
• kids can be asymptomatic
• PEP must be given within 14 days of exposure
• PEP can be monovalent hepatitis A vaccine or NHIG - depending on age, immunosuppression and contraindications to vaccination.

Pathogen and disease characteristics:

• vaccine preventable viral disease transmitted via fecal oral route from ingestion of contaminated food or water (can also be sexually transmitted)
• approx 50% cases acquired overseas
• children under 6 years often asymptomatic and can transmit to others
• risk of severe disease increases with age.
• outbreaks linked to contaminated foods (berries, contaminated shell-fish, lettuce, sun dried tomatoes); institutional settings (aged care centres and childcare centres); infectious food handlers; MSM; IVDU
• incubation period averages 28-30 days with range of 15-50 days: acquisition period = days 50 to 15 (35 days in total) prior to symptom onset (commonly used in outbreak case definitions).
• infectious period from two weeks before the onset of prodromal symptoms to either one week after the onset of jaundice or two weeks after the onset of prodromal symptoms in the absence of jaundice.
• faecal shedding may persist for months in infants and children and in the immunosuppressed.
• virus can remain infectious for at least one month at room temperature on environmental surfaces, and transfer on fomites important in some settings (e.g. childcare centres).

Clinical presentation

• In adults, acute onset of prodromal symptoms including fatigue, malaise, anorexia, nausea, vomiting, fever and abdominal discomfort, followed a few days later by dark-coloured urine, light-coloured stools, jaundice and pruritis
• Signs are usually jaundice and hepatomegaly
• Atypical presentations include prolonged cholestasis, relapsing hepatitis (~20% patients) and extra hepatic disease (fading rash, arthritis, glomerulonephritis, neurological or blood disorders.
• Case fatality varies from 0.1% in children to 2.1% in adults aged >40 years. Death is usually due to fulminant hepatitis, which is more common in older people, immunosuppressed people, people with chronic liver disease and people with HBV or HBC.

Diagnosis:

• IgM anti-HAV antibodies in combination with clinical/epi evidence of infection.
• serology from all positive non-overseas acquired should be sent to reference laboratory for genotyping.

Case management:

• Obtain travel history for aquisition period (from 15 days to 50 days prior to symptom onset).
• Determine whether case is a food-handler or HCW;
• If no history of travel to endemic countries obtain information on risk factors for exposure: household or sexual contacts who have been ill; IVDU; food history; recreational water exposure; exposure to sewerage; attendance or employment in child care services, aged care facility; correctional facility by the case or household contacts.

Case exclusion

• Case must not prepare food be excluded from childcare/school or work settings that may put others at risk for duration of infectious period (from 2 weeks prior to prodrome onset to 2 weeks after prodrome onset or 1 week after jaundice onset).
• Single room with own bathroom if living in residential facility (aged care or corrections)

Case education:
- Verbally counsel and give fact sheet with information about the disease, importance of good hand hygiene, don’t attend preschool or childcare, don’t provide personal care to others, share utensils or towels, don’t prepare or handle ready to eat food or drink for others during infectious period, have sex, IVDU, work as a food handler.

Contact management:

• Contacts include immediate family; household members; sexual partners; people who consumed ready to eat food or drinks prepared by the case; if case wears nappies then anyone who provided direct care to the case; if case attends childcare or preschool then other people in same care group or sharing toilet are considered household-like contacts; anyone sharing IVDU with case.
• If no previous infection or immunisation, PEP should be offered to household and house-hold like contacts within 14 days of onset of prodromal symptoms.
• Monovalent hep A vaccine should be given if contacts are healthy and aged from 12 months to 40 years.
• NHIG given if aged less than 12 months or vaccine contraindicated
• NHIG plus monovalent HepA vaccine given if aged over 12 months with chronic liver disease or immunosuppression.
• risk assessment for HepA vaccine versus NHIG for people aged over 40 years as rates of seroconversion by 14 days decline with age.

Contact education:
- Give fact sheet, counsel to watch for symptoms and seek medical attention for 50 days from first exposure, hand hygiene advice, voluntary exclusion for contacts who work in high risk settings.

Groups recommended for routine vaccination:

• Aboriginal and Torres Strait Islander people
• People with chronic liver disease
• People with developmental disabilities
• People working in at-risk occupation (remote First people communities, plumbers, childcare workers, disability workers
• Travellers to endemic countries
• MSM, IVDU, correctional facility inmates.

Question 3

Invasive Meningococcal Disease

Answer 3

Key memory points:

• incubation period 1-7 days
• isolate cases until 24 hours Abx treatment
• identify high risk contacts (household/house-hold like/intimate/childcare/long-haul travel/HCW).
• contact trace back 7 days prior to symptom onset to 24 hours post initiation Abx
• clearance antibiotics: ciprofloxacin (adults, children, women on COCP - single oral dose required), ceftriaxone (pregnant women - single IM dose), rifampicin (preferred for children but must be taken BD for two days and can cause orange discolouration side effects).
• all lower risk and higher risk contacts should be provided with information.
• goal of public health response is to prevent ongoing transmission of a potentially more virulent strain.
• organisation outbreak (2 cases in 4 week period) = two or more probably or confirmed cases in people who are not close contacts but have an organisational affiliation, with onset in a four week interval.
• community outbreak (3 cases in 3 month period)= three or more confirmed or probable cases of IMD where there is no direct epi link between cases, with onset in a 3 months interval among persons residing in the same area and the primary attack rate is at least 10 per 100 000.
• in Indigenous communities, community-wide action should be taken if there are 2 or more cases of same serotype in 4 week period.

Disease characteristics

• neisseria meningitidis is a gram-negative diplococcus that is a commensal organism in humans
• droplet transmission
• six serogroups account for majority of cases (A,B,C,W,X,Y) - vaccine preventable for 5 serotypes (ACWY and B). B serogroup used to be the predominant strain, however upsurge in W in recent years. W and Y disease occurs over a more diverse age range and may present with less typical clinical manifestations.
• carriage rate varies from 3-25% of the population; varies with age with peak carriage in young adults 20-24 years; associated with male gender, coincident URTI, low SES, smoking, frequency of intimate kissing and the number and closeness of social contacts.
• invasive infections most commonly associated with sepsis and meningitis, but can also cause pneumonia, septic arthritis, epiglottitis, pericarditis, conjunctivitis and urethritis.
• case fatality rate of 5-10%; long term sequelae in 10-20%.
• seasonality with most cases occurring from June to September each year.
• bimodal age distribution, with highest rates in <5’s and 15-19’s.
• usually diagnosed on PCR from blood or CSF or from culture.

Case management

• Abx Rx according to the therapeutic guidelines is the responsibility of the treating doctor
• ensure isolation with standard and droplet precautions until 24 hours after initiation of Abx, particularly whilst undertaking any airway management (notify hospital infection control).

Contact management

• higher risk contacts are household or household-like contacts, intimate contacts, childcare contacts (two full days in same room or 20 hours cumulative over week); passengers seated immediately adjacent during long-distance travel of 8 or more hours, HCWs who have had unprotected close exposure of their airway during airway management.
• higher risk contacts should be given clearance antibiotics if these can be administered within 4 weeks of contact and a fact sheet. For ACWY, unvaccinated higher risk contacts can also be vaccinated. Vaccination as PEP for MenB is not usually recommended as single dose inadequate to confer protection.
• clearance antibiotics are ciprofloxacin for adults, children and women on COCP, ceftriaxone IM for pregnant women, rifampicin for young children.
• lower risk contacts should just be provided with information.

Education:
- provide fact sheet to network of contacts.

Outbreaks:

• challenging due to the intense public concern, media interest and limited evidence to guide best practice.
• epi suggestive of an outbreak: increased rate of disease; clustering of cases in an age group or a shift in the age distribution of cases; and phenotypic and/or genetic similarity among strains causing disease in the population.
• elements of the response include a situation review to determine if there is an outbreak and its extent; establishment of a response team and a site visit (if appropriate); establishment of heightened surveillance; determination of the population at risk and calculation of age-specific and region-specific attack rates where indicated; decisions on what action is to be taken, tailored to the setting; provision of adequate information to all contacts and other people as indicated, including healthcare providers, affected communities or groups, the media and wider public; provision of Abx and vaccination where appropriate; review of all actions taken and dissemination of final report.
• primary (index) case - case that occurs in absence of previous known close contact with another case and is subsequently associated with a co-primary or secondary case.
• co-primary case - a close contact who develops disease within 24 hours of onset of illness in a primary case
• secondary case - a close contact who develops disease more than 24 hours after onset of illness in a primary case where the available microbiological characterisation of the organisms is the same.
• organisation outbreak = two or more probably or confirmed cases in people who are not close contacts but have an organisational affiliation, with onset in a four week interval. Clearance antibiotics should be considered for a wider group than household-like contacts. Co-primary or secondary cases should not be counted when determining whether criteria for provision of organisation-based clearance antibiotics have been met, because they are household-like contacts.
• community outbreak = three or more confirmed or probable cases of IMD where there is no direct epi link between cases, with onset in a 3 months interval among persons residing in the same area and the primary attack rate is at least 10 per 100 000. Co-primary and secondary cases should be counted as one case when determining whether epi criteria met. Need to consider epi of cases and local population characteristics and consider targeted vaccination campaign.
• in Aboriginal and Torres Strait Islander communities, action targeted to all community members should be considered if there are two or more cases in a remote aboriginal or Torres Strait islander community with a 4 week period of the same strain.

Contacts of meningococcal conjunctivitis should be managed as per invasive disease.

Vaccination

• Men ACWY is on NIP for infants aged 12 months and for adolescents aged 14-16 years
• Men ACWY and MenB on NIP for all people with asplenia, hyposplenia, complement deficiency and those undergoing treatment with eculizumab.
• MenB is on NIP for Indigenous people at 2/4/6/12 months (no catch-up).
• Travellers to areas with higher incidence of meningococcal disease or mass gatherings (such as the Hajj are recommended to be vaccinated).
• Young adults and smokers also recommended to be vaccinated.

Question 4

Pertussis

Answer 4

Key memory points:

• aim is to prevent disease in children aged less than 6 months and women in their final month of pregnancy, with particular focus on household, child care and healthcare exposures.
• incubation period ranges from 4-21 days; usually 7 to 10 days.
• infectious period is from onset of catarrhal symptoms until 21 days after onset of cough; 14 days after onset of paroxysmal cough; until 5 days effective antibiotic therapy completed.
• exclude from work, school, preschool, childcare etc until no longer infectious.
• Close contacts are those with face-to-face exposure (within 1 metre) to an infectious case for a single period of at least one hour and household (or household-like) contacts.
• Subset of high risk close contacts should be given Abx prophylaxis, which must be given within 14 days of first contact with infectious case.
• Specific recommendations in SoNG for certain settings and need for Abx and exclusion. Non or incompletely vaccinated people may require exclusion from high risk settings until 5 days Abx PEP or 14 days if no PEP.
• no action required for cases notified >21days after onset of paroxysmal cough or >28 days after onset of any cough unless part of a cluster.
• vaccination on NIP for infants (2/4/6 months), 4 years, adolescents (year 7 students with HPV), pregnant women between 20 and 32 weeks.

Disease characteristics

• vaccine preventable and caused by bacterium bordatella pertussis
• transmitted by large droplet infection or direct contact with discharges from respiratory mucous membranes of infectious people.
• highly contagious with attack rate of up to 80% in susceptible contacts.
• catarrhal stage characterised by insidious onset of runny nose, sneezing, absent or low grade fever and a mild occasional cough.
• cough gradually becomes paroxysmal after 1-2 weeks, and may end in vomiting, cyanosis or inspiratory whoop.
• infants more likely to present with gagging, gasping, cyanosis, apnoea or non-specific signs such as poor-feeding.
• post-tussive vomiting is strongly suggestive of pertussis in adults.
• most common complication is pneumonia and encephalopathy is a rare complication.
• case fatality rate of around 0.5% in infants less than 6 months old.
• epidemics tend to occur every 3-4 years.

Diagnosis

• NAT is the method of choice, unless presentation delay beyond 4 weeks from cough onset or 3 weeks from onset paroxysmal cough, after which serology may be better.
• NAT on nasopharyngeal swabs preferable. Throat swabs may also be used, but lower sensitivity.
• Serology is problematic, as IgA and IgG may be elevated for an unknown period following vaccination.

Case management

• it is the responsibility of the treating doctor to treat infectious cases and consider the need for further public health action for any high risk contacts.
• in ACT, treating doctor is sent a case/contact form to complete and return to CDC section.
• for cases considered high public health priority (children less than 5; people known to be in contact with infants, women in last month pregnancy), contact the treating doctor or case to ensure appropriate case and contact management.
• cases should be given 5 day course of an appropriate antibiotic (macrolide); antibiotics reduce infectious period but often don’t help symptoms.
• if treatment starts any later than 14 days from onset of cough, by the time 5 days of treatment is completed, case will be close to end of their 21 day infectious period.
• exclude from childcare facilities, school, work or setting where there are people at risk until 5 days Abx therapy completed.
• give factsheet.
• infectious cases in hospital should be managed with droplet precautions and single room until 5 days treatment completed.

Outbreaks
- defined as two or more cases which share a plausible epi link. Depending on the people affected and nature of the setting, control strategies may include active case finding; epi studies to determine risks of infection, alerts to doctors in community, cocooning vaccine initiatives, community wide promotion of vaccination.

Contact management

• Aim of identifying contacts is to alert them to the possibility that they may develop disease and recommend Abx prophylaxis for infants <6 months or people who may transmit to these infants.
• Close contacts are those with face-to-face exposure (within 1 metre) to an infectious case for a single period of at least one hour; infants exposed for shorter periods may still require PEP.
• Household and house-hold like contacts are also considered close contacts.
• All close contacts should receive information about pertussis (e.g. fact sheet).
• A subset of close contacts are considered high risk contacts and should be given Abx prophylaxis; expectant parents, all household members in a house that has infant < 6months, staff working with infants or pregnant women, children in childcare centre who have contact with infants <6 months age.
• Abx must be given within 14 days of first contact with an infectious case.
• Non or incompletely vaccinated people that receive Abx for PEP in high risk settings (e.g. childcare) must be excluded for 5 days while on antibiotics or 14 days if they don’t take antibiotics.
• No evidence that Abx PEP is helpful in settings such as primary schools, high schools, tertiary institutions and workplaces.

Question 5

Hepatitis B

Answer 5

Key memory points:

• vaccine preventable BBV that is most prevalent in certain migrant populations, First Nations people, IVDU and MSM.
• Burden of disease arises from cirrhosis, portal hypertension and HCC.
• incubation period varies from 45 to 180 days and most commonly 60 to 90 days.
• underdiagnosis of chronic HBV and lack of regular clinical care and treatment for those living with HBV are significant public health issues; Australia not meeting targets for HBV care cascade of 80% diagnosed; 50% receiving care and 20% receiving treatment.
• treatment is recommended for people with elevated HBV viral load and abnormal LFTs or for those who have advanced liver disease.

Disease characteristics

• transmitted via parenteral, percutaneous or mucosal exposure to infectious bodily fluids (blood, vaginal fluids, semen and saliva if contaminated with blood) of an infected person.
• vertical transmission also occurs.
• overcrowded homes and settings with high prevalence of violence and injury pose increased risk of transmission.
• risk of transmission to an uninfected person linked to the hepatitis B surface antigen and hepatitis B e antigen status of the source patient.
• Incubation period depends on amount of virus in inoculum, mode of transmission and host factors.
• Infectivity during acute infections in adults commences several weeks before the onset of symptoms and usually lasts 4-5 months while HBsAg is present. People with chronic infection remain infectious for life.
• only 30-50% of adults and less than 10% of children with acute HBV have symptoms
• fulminant hepatitis occurs in less than 1% of acute HBV infections.
• following acute infection, approximately 5% of adults but up to 95% of neonates and 20-30% of children aged 1-5 years become chronically infected.
• chronic infection defined as detection of HBsAg more than 6 months after prior evidence of infection. Chronic infection usually asymptomatic until clinical signs of liver disease (cirrhosis, portal hypertension, HCC) become apparent.
• progression of liver disease promoted by HIV co-infection, co-existing liver disease due to HCV/HDV/EtOH
• around 25% of those with chronic disease will die prematurely due to cirrhosis and/or HCC. HCC has poor prognosis, with most only surviving 1-2 years.
• In Aus, those most at risk of HBV are those born in intermediate or high prevalence countries (due to perinatal or early childhood infection); First Nations people (particularly adults infected perinatally or in early childhood prior to universal vaccination); infants born to mothers with CHB; people in custodial settings; people with HIV or HCV
• 10% people in Australia with HBV are First Nations people.
• most primary liver cancer in Australia is attributable to chronic viral hepatitis - expected to continue growing due to ageing population and low uptake antiviral treatment.
• WPRO has the highest burden of HBV related cirrhosis and liver cancer in the world.

Epidemiology in Australia

• Rates of newly acquired infections have been declining since introduction of HepB vaccines in adolescents in 1997 and infants in 2000
• Newly acquired infections occur mostly in adults aged 25 to 39 years of age and are most often attributed to IVDU, sexual contact and occasionally skin penetrating procedures.
• Reliability of notification data is limited due to nature of disease as most new infections are asymptomatic and go undetected.
• Detection of chronic infections relies on regular screening in at risk populations.
• 10% people in Australia with HBV are First Nations people.
• First Nations people have ~3 times higher rate of newly acquired HBV infection.
• Higher rates of hospitalisation, mortality and morbidity from HBV infection for First Nations people.
• Estimated 226 000 people living with HBV in Aus in 2018; 70% born overseas/23% Australian born non-indigenous and 7% First Nations.
• Estimated that ~68% of people living with HBV have been diagnosed, below the national target of 80%, with only 22% receiving regular clinical care.
• Target for 20% of people with chronic HBV to be on treatment; only 9% estimated to be on treatment in 2018.
• Most primary liver cancer is attributable to chronic viral hepatitis; rates of HCC have been increasing in Australia with a 200% increase since 1982.

Risk mitigation

• screening of donated blood and tissues
• antenatal screening
• infant hepB vaccination
• vaccination of people at increased risk
• infection control in settings where skin penetration occurs
• promotion of safer sex
• promotion of safer injecting practices

Testing
- who to test outlined in National Hep B testing policy

Question 6

Influenza - single case

Answer 6

Key memory points:

• incubation period usually 2 days but range of 1-4 days.
• infectious period for adults is from 24 hours prior to Sx onset to 24 hours after resolution of fever provided either 72 hours have elapsed since commencing antiviral meds or 5 days post Sx onset.
• predominantly droplet and fomite transmission
• antivirals must be given within 48 hours for maximal impact on viral shedding and symptom resolution.
• vaccination on NIP for high risk groups (>65, pregnant, Aboriginal over 6 months, children 6 months-5 years, people over 6 months with certain medical conditions).
• National influenza surveillance scheme monitors ILI and lab confirmed influenza using NNDSS data, influenza associated ED presentations and hospitalizations, sentinel ILI reporting from GPs (e.g. Australian Sentinel Practices Research Network/ASPREN), ILI related community level surveys (flu tracker, calls to health direct) and sentinel laboratory results.

Special situations:

• schools and childcare settings: encourage vaccination, staying home when sick, resp hygiene, provide fact sheets/letters
• boarding schools: as above but isolate and cohort.
• Aboriginal communities: increased prevalence of people with high risk medical conditions, reduced access to hygiene aids, overcrowding and living conditions that may facilitate transmission, reduced access to healthcare and diagnostic facilities. Need to work with local health services and community leaders, provide culturally appropriate education materials, consider vaccination as disease control measure, consider treatment of all ILI without waiting for confirmation, consider antiviral prophylaxis for vulnerable community members who were close household contacts of an infectious ILI case.
• cruise ships: consider screening incoming passengers for ILI, actively promote vaccination, remind passengers of hygiene measures, ensure ready access to hand hygiene measures, isolate ill passengers and crew, increase frequency of cleaning.

Guidelines :

• CDNA seasonal influenza SoNG;
• Australian Health Management Plan for Pandemic influenza (AHMPPI) guidelines;
• Guidelines for the prevention, control and public health management of influenza outbreaks in residential care facilities in Australia.
• ACT: nil

Disease

• Urgent priority for novel subtypes
• High priority for outbreaks in high risk settings
• RNA orthomyxoviridae viruses. A types classified according to H and N proteins. B types belong to either Victoria or Yamagata lineages.
• vaccines need adjustment each season due to antigenic drift.
• antigenic shift can lead to pandemics and occurs when the genetic reassortment of RNA from two different strains of influenza A results in the abrupt appearance of an influenza A virus with novel H or N proteins.
• natural hosts of flu A are birds (particularly ducks and waterfowl), but pigs, horses and humans also co-hosts.
• droplet and fomite transmission; aerosol transmission can also occur in confined spaces or during AGPs.
• children and immunocompromised may shed virus for longer and therefore infection prevention and control precautions must be maintained for longer.
• can present atypically in the elderly with mental status changes, anorexia and exacerbation of underlying chronic conditions.

Prevention activities:

• vaccination and annual vaccination campaigns
• education on respiratory hygiene and importance of staying home when unwell and not visiting priority populations or settings
• antiviral medication

Control:
- focus is on control of outbreaks in high risk settings

Surveillance:

• ACT produces weekly influenza surveillance reports during the flu season, usually from May to October.
• Australian influenza surveillance report published fortnightly during flu season.
• National influenza surveillance scheme monitors ILI and lab confirmed influenza using NNDSS data, influenza associated hospitalizations, sentinel ILI reporting from GPs, ILI related community level surveys (flu tracker, calls to health direct) and sentinel laboratory results.

Question 7

Influenza - outbreak

Answer 7

Key memory points:

• outbreak = 3 or more residents or staff with ILI within a 72 hours period.
• incubation period = 1-4 days (average 2 days)
• infectious period = 3-5 days in adults and up to 7 days or occasionally longer in children.
• ILI definition: sudden onset of symptoms with at least one respiratory symptom (cough/sore throat/shortness of breath) and at least one systemic symptom (fever/malaise/headache/myalgia).
• key elements of outbreak management: preparation/response/monitor/conclude.
• outbreak can be declared over when no new cases have occurred within 8 days following the onset of symptoms in the last resident case (8 days is the sum of the usual infectious period of 5 days plus the maximum incubation period of 3 days).
• staff with ILI should be excluded from work for at least 5 days or until they are symptom free, whichever is longer.

Guidelines:

• CDNA guidelines for prevention, control and public health management of influenza outbreaks in residential aged care facilities - has lots of useful tools e.g. checklists, signage etc.
• ACT Health internal SOP

Vaccination:

• Vaccination reduces risk of hospitalisation from influenza and risk of pneumonia and reduces all-cause mortality in residents aged 65 years and over.
• RCFs should have vaccination policy in place that aims for 95% coverage of residents and staff and should maintain a vaccination register. They should undertake annual planning for vaccination of residents and staff.
• Family members should be encouraged to be vaccinated also.

ILI outbreaks

• Facilities should have an outbreak management plan and ensure they have adequate supplies of PPE and cleaning materials, staff are appropriately trained, policies to support use of antivirals (note assessment of renal function required for antivirals), vaccination policies in place. Checklists and tools are available to assist with planning.
• RCFs should have systems in place for the early detection and recording of ILI in staff and residents and should collect samples for testing.
• Implement control procedures aimed at the residents/staff and facility.
• Main control measures are vaccination, hand hygiene, PPE, isolation and cohorting of residents, cohorting of staff (only vaccinated should care for ill residents), increased cleaning, promoting respiratory hygiene and cough etiquette, minimizing resident transfer or transport, visitor restriction and signage.
• Communicate when outbreak is declared over and consider a debrief.