First reported outbreak of locally acquired hepatitis E virus infection in Australia.

OBJECTIVE: To determine the source and extent of a locally acquired hepatitis E virus (HEV) infection outbreak. DESIGN, SETTING AND PARTICIPANTS: A cluster of notified cases of HEV infection linked to a single restaurant (X) was identified in May 2014. People with laboratory-confirmed HEV infection in New South Wales between January 2013 and December 2014 were interviewed about potential risk factors for HEV infection. Co-diners at restaurant X and patients with suspected but unexplained viral hepatitis were retrospectively tested. Foods eaten by the infected persons were compared with those of seronegative co-diners. HEV RNA detected in sera from infected persons was sequenced and genotyped. Implicated foods were traced back to their sources. MAIN OUTCOME MEASURES: Potential sources of infection, including overseas travel and foods eaten, and origin of implicated food products. RESULTS: In 55 serologically confirmed cases of HEV infection, 24 people had not travelled overseas during their incubation periods. Of the 24, 17 reported having eaten at restaurant X, 15 of whom could be interviewed. All reported consuming pork liver pâté, compared with only four of seven uninfected co-diners (P < 0.05). The other seven people with locally acquired infections each reported consuming a pork product during their incubation periods. HEV RNA was detected in 16 of the 24 cases; all were of genotype 3. Sequencing indicated greater than 99% homology among restaurant X isolates. HEV RNA was isolated from pork sausages from a batch implicated in one of the locally acquired infections not linked with restaurant X. The pork livers used for pâté preparation by restaurant X were traced to a single Australian farm. CONCLUSIONS: This is the first reported HEV outbreak in Australia. HEV should be considered in patients presenting with a compatible illness, even without a history of overseas travel. Pork products should be thoroughly cooked before consumption.

An outbreak of enterovirus 71 in metropolitan Sydney: enhanced surveillance and lessons learnt.

OBJECTIVE: To report the findings of the enhanced surveillance set up in New South Wales in response to the recent outbreak of human enterovirus 71 (EV71) infection. DESIGN AND SETTING: A two-armed enhanced public health surveillance system including statewide emergency department surveillance and clinical surveillance at the Sydney Children's Hospitals Network. PARTICIPANTS: Children aged less than 10 years with suspected or confirmed enterovirus infection. MAIN OUTCOME MEASURES: Epidemiology of the outbreak, including weekly case counts, demographic information, geographic spread of the outbreak, and clinical presentation and progression. RESULTS: Statewide weekly case counts indicate that an epidemic of EV71 infection occurred in NSW from December 2012 until May 2013. Around 119 children were reported with disease severe enough to warrant admission to a tertiary Sydney children's hospital. Cases were spread throughout the Sydney metropolitan area and there is some evidence of geographic migration of the outbreak. Presenting features included fever, lethargy, myoclonus and skin rash. Only 24% of cases presented with classical hand, foot and mouth disease. CONCLUSIONS: EV71 infection is likely to continue to be a public health problem in Australia. Surveillance of routinely collected emergency department data can provide a useful indication of its activity in the community.

A state-wide information campaign during a pertussis epidemic in New South Wales, 2010.

Pertussis notifications increased dramatically in New South Wales in 2008, exceeding the rates in previous epidemic years. A state-wide, multi-faceted campaign was launched in March 2009 to provide information about pertussis prevention. A population-based survey was conducted using a Computer Assisted Telephone Interviewing facility to assess the effectiveness of sending letters to households with young infants. A representative sample of 1,200 adults across all 8 area health services was interviewed between July 2009 and September 2010, with responses weighted against the state population. Many respondents (39.7%) reported receiving the letter, while fewer (29.6%) reported receiving an adult pertussis booster in the last year, mostly in response to General Practitioner advice (40.4%). Letter receipt was associated with the uptake of an adult pertussis booster in the past 12 months by respondents (OR 5.8; 95%CI 4.1, 8.2) and other adults in the household (OR 5.1; 95%CI 3.5, 7.5), as well as knowledge about pertussis prevention. Health providers remain crucial for vaccination decision making; however letters may have contributed to an increased uptake of pertussis booster vaccination and knowledge. Health authorities may consider mailing households in future pertussis epidemics as a component of a wider communication strategy.

Infectious diseases in returned travellers, NSW, 2010-2011.

AIM: To quantify the proportion of selected notified diseases in NSW attributable to overseas travel and assess the quality of data on travel-associated risk factors, to inform prevention strategies. METHODS: 2010 and 2011 notification data for dengue, hepatitis A, hepatitis E, malaria, paratyphoid fever, shigellosis and typhoid fever were extracted from the NSW Notifiable Conditions Information Management System and analysed for travel-associated risk factors. RESULTS: Where place of acquisition was known, the proportion of cases for whom the disease was acquired overseas ranged from 48.7% for shigellosis to 100% for hepatitis E, malaria and typhoid. Over half of hepatitis A (53.3%), hepatitis E (74.2%), malaria (54.5%), paratyphoid (53.3%) and typhoid (65.7%) cases were associated with travel to the person's country of birth. Hepatitis A vaccination rates were significantly lower among overseas-acquired than locally-acquired cases (4.8% vs 22.2%, Χ(2)=6.58, p<0.02). CONCLUSION: A large proportion of selected enteric and vectorborne disease case notifications were associated with overseas travel. All potential travellers should be made aware of the risks and available preventive measures, such as vaccination against hepatitis A and typhoid fever, taking precautions with food and water and use of malaria chemoprophylaxis, where appropriate. Improvements in data on risk factors, reason for travel and barriers to the use of preventive measures would better inform prevention strategies.

EpiReview: tuberculosis in NSW, 2009-2011.

AIM: To describe the epidemiology of tuberculosis in NSW between 2009 and 2011 and compare with previous years. METHODS: Data from all cases of tuberculosis notified in NSW during this period were extracted from the Notifiable Conditions Information Management System. Descriptive analyses of notification data were undertaken. Incidence rates were calculated per 100000 population. RESULTS: Between 2009 and 2011, there were 1548 cases of tuberculosis notified in NSW, translating to an average annual notification rate of 7.2 per 100000 population for this period. A total of 89% (n=1371) of notified cases were overseas-born, and 1.6% (n=24) of cases were recorded as Aboriginal persons. The most common site of infection was the lung (60% of cases). Of notified cases, 68% were reported as having been tested for HIV, of which 3%(n=28) of cases had HIV/tuberculosis co-infection. There were 20 cases of multidrug-resistant tuberculosis, including one case of extensively drug-resistant tuberculosis. CONCLUSION: The notification rate of tuberculosis in NSW has remained relatively stable over the past two decades, though small incremental increases since 2003 are evident. Endemic transmission of tuberculosis within sub-groups of the NSW population, as well as the ongoing high endemnicity for tuberculosis in neighbouring countries, highlight the importance of tuberculosis control as a continued strategic priority for disease control in NSW.

Case-control study of risk factors for hospitalization caused by pandemic (H1N1) 2009.

We conducted a case-control study to identify risk factors for hospitalization from pandemic (H1N1) 2009 virus infection among persons >16 years of age in Sydney, Australia. The study comprised 302 case-patients and 603 controls. In a logistic regression model, after adjusting for age and sex, risk factors for hospitalization were pregnancy (odds ratio [OR] 22.4, 95% confidence interval [CI] 9.2-54.5), immune suppression (OR 5.5, 95% CI 2.8-10.9), pre-existing lung disease (OR 6.6, 95% CI 3.8-11.6), asthma requiring regular preventive medication (OR 4.3, 95% CI 2.7-6.8), heart disease (OR 2.3, 95% CI 1.2-4.1), diabetes (OR 3.8, 95% CI 2.2-6.5), and current smoker (OR 2.0, 95% CI 1.3-3.2) or previously smoked (OR 2.0, 95% CI 1.3-3.0). Although obesity was not independently associated with hospitalization, it was associated with an increased risk of requiring mechanical ventilation. Public health messages should give greater emphasis on the risk for severe disease among pregnant women and smokers.

Outbreaks of pandemic (H1N1) 2009 and seasonal influenza A (H3N2) on cruise ship.

To determine the extent and pattern of influenza transmission and effectiveness of containment measures, we investigated dual outbreaks of pandemic (H1N1) 2009 and influenza A (H3N2) that had occurred on a cruise ship in May 2009. Of 1,970 passengers and 734 crew members, 82 (3.0%) were infected with pandemic (H1N1) 2009 virus, 98 (3.6%) with influenza A (H3N2) virus, and 2 (0.1%) with both. Among 45 children who visited the ship's childcare center, infection rate for pandemic (H1N1) 2009 was higher than that for influenza A (H3N2) viruses. Disembarked passengers reported a high level of compliance with isolation and quarantine recommendations. We found 4 subsequent cases epidemiologically linked to passengers but no evidence of sustained transmission to the community or passengers on the next cruise. Among this population of generally healthy passengers, children seemed more susceptible to pandemic (H1N1) 2009 than to influenza (H3N2) viruses. Intensive disease control measures successfully contained these outbreaks.

EpiReview: tuberculosis in NSW, 2008.

AIM: To describe the epidemiology of tuberculosis cases notified in NSW in 2008. METHOD: Data on tuberculosis cases resident in NSW that were reported in 2008 were extracted from the Notifiable Diseases Database. Demographic, microbiological, clinical and other characteristics of cases were described. Incidence rates per 100 000 were calculated. RESULTS: In 2008, 498 tuberculosis cases were notified in NSW (7.1 cases per 100 000 population). Most cases were newly diagnosed (n = 479, 96%). The lung was the most common site of disease (n = 304, 61%). Eight of 269 tested cases (1.6%) had a HIV-tuberculosis co-infection. One case had multidrug-resistant tuberculosis. Most cases reported past residence (n = 429, 86%) or birth (n = 378, 76%) in a country with a high incidence of tuberculosis. CONCLUSION: The incidence of tuberculosis in NSW increased slightly in 2008. Most cases had links to countries with a high tuberculosis incidence.

Review of the 2008-2009 pertussis epidemic in NSW: notifications and hospitalisations.

In 2008 and 2009 increased numbers of pertussis notifications were reported in NSW. During the epidemic period, the pertussis notification rate was 2.7 times higher than the previous 5-year average. Rates of pertussis notifications and hospitalisations were highest among infants aged less than 1 year across all years studied. Compared to previous years, the notification rate for children aged 1-4 years increased dramatically and was particularly striking for children aged 3 years with notifications exceeding those for infants in 2009. Changes in testing practices during the epidemic period, including a significant increase in the use of polymerase chain reaction, may account for some of the relative increase in size of the 2008-2009 outbreak compared with previous outbreak years.

Investigation of equine influenza transmission in NSW: walk, wind or wing?

OBJECTIVES: An outbreak of equine influenza occurred in New South Wales in 2007. In addition to the local spread of the disease between bordering properties, windborne spread over several kilometres had been postulated as a possible method of transmission in this outbreak. This study aimed to describe potential modes of transmission for a property infected with equine influenza where no apparent epidemiological links to other infected properties were reported. METHODS: A semi-structured questionnaire was administered to owners of affected properties. The questionnaire collected detailed transmission-risk information, including personnel movements, equipment sharing, and horse and other animal movements. RESULTS: Interviews with property owners from one geographic area suggested the potential for birds and other animals - rather than wind - to facilitate transmission of equine influenza. CONCLUSION: This study described the potential for mechanical spread of equine influenza. Further research, including laboratory testing of bird plumage following contact with infected horses, may be useful to confirm the possibility of avian fomite transmission.

Vaccine failures and vaccine effectiveness in children during measles outbreaks in New South Wales, March-May 2006.

During March to May 2006 the highest incidence of measles in New South Wales since 1998 provided an opportunity to estimate the effectiveness of the measles-mumps-rubella (MMR) vaccination program in preventing childhood measles, and describe any differences in clinical presentation between vaccinated and unvaccinated children. We reviewed records of all 33 notified cases of measles in children aged 1-14 years during a state-wide outbreak in New South Wales from March - May 2006. Six of the children had a confirmed history of vaccination with at least 1 dose of MMR. The children with previous vaccination tended to have milder disease than those without vaccination as judged by their reported number of symptoms and hospitalisation rates. The vaccinated children were less likely to have a typical measles rash. Two of the cases in previously vaccinated children may be due to secondary vaccine failure, although a lack of complete diagnostic testing limits our ability to confirm this. Vaccine effectiveness after receiving at least 1 dose of MMR is estimated to be 96% (95% CI 77.8-99%). MMR vaccination was effective in preventing measles in children during these outbreaks.

The effectiveness of prophylaxis for measles contacts in NSW.

OBJECTIVES: As international estimates of the effectiveness of post-exposure prophylaxis of measles vary, we sought to determine the effectiveness of post-exposure prophylaxis with either vaccine or immunoglobulin in susceptible persons with known measles contact. METHODS: Data were obtained on all cases of measles notified in NSW between 1 March and 31 May 2006 and their contacts. The effectiveness of prophylaxis was calculated using the cohort method. RESULTS: During March to May 2006, 57 cases of measles were notified and 1760 measles contacts were identified, of which 553 were classified as susceptible. The calculated effectiveness of post-exposure prophylaxis with vaccine or immunoglobulin in preventing measles was 83.3% (95% CI: 27-96%). CONCLUSION: Post-exposure immunisation remains an effective tool for preventing secondary cases of measles.

The evaluation of web-based data collection for enhanced surveillance of cryptosporidiosis.

Following an increase in the number of people diagnosed with cryptosporidiosis in November 2005, the Communicable Diseases Branch initiated enhanced surveillance using a developmental version of NetEpi Collection, an open-source, web-based data collection tool. We evaluated the usefulness of NetEpi Collection for enhanced surveillance, using the Centers for Disease Control and Prevention's Updated Guidelines for Evaluating Public Health Surveillance Systems as a guide. Most staff (73 per cent) who used NetEpi Collection found it easy to use. Although ongoing support was thought to be adequate by 82 per cent of respondents who used NetEpi Collection, 36 per cent reported that training was limited and 27 per cent reported technical problems such as internet, server and password problems. In order to improve its usefulness in enhanced surveillance, training in NetEpi Collection should be enhanced and the stability of the system improved.

EPIREVIEW. Pertussis in New South Wales, 1993-2005: the impact of vaccination policy on pertussis epidemiology.

OBJECTIVE: To assess whether changes in vaccination policy have affected the epidemiology of pertussis in NSW between 1993 and 2005. METHODS: Surveillance data from the NSW Notifiable Diseases Database was reviewed for the period. RESULTS: 35,695 cases of pertussis were notified; annual incidence rates varied from 18.4 to 84.2 per 100,000 people. The highest rates of pertussis were consistently found in infants aged 0-6 months. Rates of disease in other age groups changed markedly over the study period, with high rates currently observed in adult age groups. CONCLUSIONS: New strategies may be needed to control pertussis in infants and in adults who now comprise the largest proportion of cases.

Health surveillance among a team of Australian health workers assisting tsunami victims in Aceh, Indonesia.

OBJECTIVE: To determine the extent and nature of health-related behaviours and outcomes among members of the first foreign medical team to arrive in Aceh, following the Boxing Day tsunami in 2004. METHODS: A cross sectional survey of team members 4 weeks after return from Aceh. RESULTS: Compliance with antimalarial chemoprophylaxis and insect repellent was high while in Aceh, but only one-third completed the course of chemoprophylaxis. The provision of prepackaged food and water was likely to have prevented enteric disease. Members reported mosquito bites, fatigue, sunburn, headache and anxiety about earthquakes. CONCLUSIONS: Provision of prepackaged food and water, preventive measures and information to members may be important in avoiding illness in such teams.

An epidemiological investigation into an outbreak of rash illness among methadone maintenance clients in Australia.

In late 2004, NSW Health received several reports of a serious desquamating rash among clients of the methadone program. We sought to identify the extent and likely cause of this outbreak. We initiated active surveillance for cases throughout Australia, a survey of dosing points in NSW, and a case control study of clients receiving methadone syrup (MS) at two clinics. Between October 2004 and March 2005, 388 cases were identified, largely in NSW. The dosing point survey found almost all cases were clients prescribed MS (attack rate 4.5%). In multivariate analysis of data from dosing points that dispensed MS, use of take away doses or location of the dosing point in greater western Sydney were associated with illness. In the case control study, MS injection, use of street MS, high doses of MS, frequent takeaway doses, or use of benzodiazepines were associated with illness. Testing found no abnormality in associated batches of MS. Batches of MS temporally associated with the outbreak were quarantined from use and the outbreak subsided. While a direct causal link could not be established, available evidence suggests that a contaminant may have caused the outbreak. Epidemiological analyses are important for assessing concerns about product safety following marketing approval.