Arboviral diseases and malaria in Australia, 2014­15: Annual report of the National Arbovirus and Malaria Advisory Committee

This report describes the epidemiology of mosquito-borne diseases of public health importance in Australia during the 2014­15 season (1 July 2014 to 30 June 2015) and includes data from human notifications, sentinel chicken, vector and virus surveillance programs. The National Notifiable Diseases Surveillance System received notifications for 12,849 cases of disease transmitted by mosquitoes during the 2014­15 season. The Australasian alphaviruses Barmah Forest virus and Ross River virus accounted for 83% (n=10,723) of notifications. However, over-diagnosis and possible false positive diagnostic test results for these two infections mean that the true burden of infection is likely overestimated, and as a consequence, revised case definitions were implemented from 1 January 2016. There were 151 notifications of imported chikungunya virus infection. There were 74 notifications of dengue virus infection acquired in Australia and 1,592 cases acquired overseas, with an additional 34 cases for which the place of acquisition was unknown. Imported cases of dengue were most frequently acquired in Indonesia (66%). There were 7 notifications of Zika virus infection. No cases of locally-acquired malaria were notified during the 2014­15 season, though there were 259 notifications of overseas-acquired malaria and one notification for which no information on the place of acquisition was supplied. Imported cases of malaria were most frequently acquired in southern and eastern Africa (23%) and Pacific Island countries (20%). In 2014­15, arbovirus and mosquito surveillance programs were conducted in most of the states and territories. Surveillance for exotic mosquitoes at international ports of entry continues to be a vital part of preventing the establishment of vectors of mosquito-borne diseases such as dengue to new areas of Australia. In 2014-15, there was a sharp increase in the number of exotic mosquitoes detected at the Australian border, with 36 separate exotic mosquito detections made, representing a 280% increase from the 2013-14 period where there were 13 exotic mosquito detections.

Arboviral diseases and malaria in Australia, 2012-13: Annual report of the National Arbovirus and Malaria Advisory Committee.

This report describes the epidemiology of mosquito-borne diseases of public health importance in Australia during the 2012-13 season (1 July 2012 to 30 June 2013) and includes data from human notifications, sentinel chicken, vector and virus surveillance programs. The National Notifiable Diseases Surveillance System received notifications for 9,726 cases of disease transmitted by mosquitoes during the 2012-13 season. The Australasian alphaviruses Barmah Forest virus and Ross River virus accounted for 7,776 (80%) of total notifications. However, over-diagnosis and possible false positive diagnostic test results for these 2 infections mean that the true burden of infection is likely overestimated, and as a consequence, the case definitions were revised, effective from 1 January 2016. There were 96 notifications of imported chikungunya virus infection. There were 212 notifications of dengue virus infection acquired in Australia and 1,202 cases acquired overseas, with an additional 16 cases for which the place of acquisition was unknown. Imported cases of dengue were most frequently acquired in Indonesia. No locally-acquired malaria was notified during the 2012-13 season, though there were 415 notifications of overseas-acquired malaria. There were no cases of Murray Valley encephalitis virus infection in 2012-13. In 2012-13, arbovirus and mosquito surveillance programs were conducted in most jurisdictions with a risk of vectorborne disease transmission. Surveillance for exotic mosquitoes at the border continues to be a vital part of preventing the spread of mosquito-borne diseases such as dengue to new areas of Australia, and in 2012-13, there were 7 detections of exotic mosquitoes at the border.

Arboviral diseases and malaria in Australia, 2013-14: Annual report of the National Arbovirus and Malaria Advisory Committee.

This report describes the epidemiology of mosquito-borne diseases of public health importance in Australia during the 2013-14 season (1 July 2013 to 30 June 2014) and includes data from human notifications, sentinel chicken, vector and virus surveillance programs. The National Notifiable Diseases Surveillance System received notifications for 8,898 cases of disease transmitted by mosquitoes during the 2013-14 season. The Australasian alphaviruses Barmah Forest virus and Ross River virus accounted for 6,372 (72%) total notifications. However, over-diagnosis and possible false positive diagnostic test results for these 2 infections mean that the true burden of infection is likely overestimated, and as a consequence, the case definitions have been amended. There were 94 notifications of imported chikungunya virus infection and 13 cases of imported Zika virus infection. There were 212 notifications of dengue virus infection acquired in Australia and 1,795 cases acquired overseas, with an additional 14 cases for which the place of acquisition was unknown. Imported cases of dengue were most frequently acquired in Indonesia (51%). No cases of locally-acquired malaria were notified during the 2013-14 season, though there were 373 notifications of overseas-acquired malaria. In 2013-14, arbovirus and mosquito surveillance programs were conducted in most jurisdictions. Surveillance for exotic mosquitoes at international ports of entry continues to be a vital part of preventing the spread of vectors of mosquito-borne diseases such as dengue to new areas of Australia, with 13 detections of exotic mosquitoes at the ports of entry in 2013-14.

Arboviral diseases and malaria in Australia, 2011-12: annual report of the National Arbovirus and Malaria Advisory Committee.

The National Notifiable Diseases Surveillance System received notifications for 7,875 cases of disease transmitted by mosquitoes during the 2011-12 season (1 July 2011 to 30 June 2012). The alphaviruses Barmah Forest virus and Ross River virus accounted for 6,036 (77%) of these. There were 18 notifications of dengue virus infection acquired in Australia and 1,390 cases that were acquired overseas, while for 38 cases, the place of acquisition was unknown. Imported cases of dengue in Australia were most frequently acquired in Indonesia. There were 20 imported cases of chikungunya virus. There were no notifications of locally-acquired malaria in Australia during the 2011-12 season. There were 314 notifications of overseas-acquired malaria and 41 notifications where the place of acquisition was unknown. Sentinel chicken, mosquito surveillance, viral detection in mosquitoes and climate modelling are used to provide early warning of arboviral disease activity in Australia. In 2011-12, sentinel chicken programs for the detection of flavivirus activity were conducted in most states with the risk of arboviral transmission. Other surveillance activities to detect the presence of arboviruses in mosquitoes or mosquito saliva or for surveying mosquito abundance included honey-baited trap surveillance, surveys of household containers that may provide suitable habitat for the dengue vector, Aedes aegypti, and carbon dioxide baited traps. Surveillance for exotic mosquitoes at the border continues to be a vital part of preventing the spread of mosquito-borne diseases to new areas of Australia.

Histamine fish poisoning in Australia, 2001 to 2013.

We report on human illness due to histamine fish poisoning outbreaks in Australia from 2001 to 2013. Histamine fish poisoning results from the ingestion of histamine contained within the flesh of certain fish species that naturally contain histidine, which has been converted to histamine by spoilage bacteria following poor handling or temperature control after harvesting. While symptoms vary, allergic symptoms such as facial flushing, headaches and rashes are frequently reported. Using the OzFoodNet outbreak register, published case reports and surveillance reports, we found data on 57 outbreaks of histamine fish poisoning, which affected 187 people, of whom 14% were hospitalised. There were no deaths reported. Outbreaks were generally small in size, with a median of 2 cases per outbreak (range 1 to 22 people), with 88% of outbreaks comprising less than 5 people. Tuna (in the family Scombridae) was the most frequently reported food vehicle, while 18 outbreaks involved non-scombridae fish. Median incubation periods among the outbreaks were short; being less than 1 hour for 22 outbreaks. The most frequently reported symptoms were diarrhoea and rash. Symptoms of facial/body flushing were reported for at least one case in 19 outbreaks and tingling, burning or swelling of the skin, especially around the lips for at least 1 case in 13 outbreaks. In 3 outbreaks, one or more cases were reported to have had respiratory distress or difficulty breathing. While the condition is often mild, improved recognition and appropriate treatment is important, as it will reduce the possibility of any severe health effects resulting from this condition. Key features of histamine fish poisoning outbreaks are the high attack rate, rapid onset, the typical symptoms and their short duration.

Assessing the threat of chikungunya virus emergence in Australia.

BACKGROUND: Chikungunya virus (CHIKV) is a major threat to Australia given the distribution of competent vectors, and the large number of travellers returning from endemic regions. We describe current knowledge of CHIKV importations into Australia, and quantify reported viraemic cases, with the aim of facilitating the formulation of public health policy and ensuring maintenance of blood safety. METHODS: Cases reported to the National Notifiable Disease Surveillance System (NNDSS) from 2002 to 2012 were analysed by place, month of acquisition, and place of residence. Rates of chikungunya importation were estimated based on reported cases and on the numbers of short-term movements. RESULTS: Between 2002 and 2012, there were 168 cases of chikungunya virus (CHIKV) imported into Australia. Victoria and New South Wales had the largest number of notifications. The main sources were Indonesia, India and Malaysia. The number of cases increased from 2008 to reach a peak in 2010 (n=64; 40%). Although Indonesia accounted for the majority of CHIKV notifications in Australia, travel from India had the highest CHIKV importation rate (number of imported cases per 100,000 travellers). CONCLUSIONS: The Australian population is increasingly at risk from CHIKV. Arrivals from endemic countries have increased concurrently with vector incursions via imported goods, as well as via local movement from the Torres Strait to North Queensland ports. An outbreak of CHIKV could have a significant impact on health, the safety of the blood supply and on tourism. Case and vector surveillance as well as population health responses are crucial for minimising any potential impact of CHIKV establishment in Australia.

Arboviral diseases and malaria in Australia, 2010-11: annual report of the National Arbovirus and Malaria Advisory Committee.

The National Notifiable Diseases Surveillance System (NNDSS) received notification of 9,291 cases of disease transmitted by mosquitoes during the 2010-11 season (1 July 2010 to 30 June 2011). The alphaviruses Barmah Forest virus and Ross River virus accounted for 7,515 (81%) of these. There were 133 notifications of dengue virus infection acquired in Australia and 1,133 cases that were acquired overseas, while for 10 cases, the place of acquisition was unknown. The number of overseas acquired cases of dengue continues to rise each year, and these are most frequently acquired in Indonesia. Sentinel chicken, mosquito surveillance, viral detection in mosquitoes and climate modelling are used to provide early warning of arboviral disease activity in Australia. In early 2011, sentinel chickens in south eastern Australia widely seroconverted to flaviviruses. In 2010-11, there were 16 confirmed human cases of Murray Valley encephalitis acquired in Australia. There was one human case of Kunjin virus infection. There were 7 notifications of locally-acquired malaria in Australia and 407 notifications of overseas-acquired malaria during the 2010-11 season.

Increasing notifications of dengue in Australia related to overseas travel, 1991 to 2012.

Dengue is an important cause of illness in travellers returning to Australia. The risk of local transmission from imported cases is of particular concern, with several large and explosive outbreaks recorded in recent years in north Queensland in areas where the mosquito vector of dengue is present. The number and proportion of dengue cases that are overseas-acquired is increasing. The number of overseas cases in 2010 and 2011 had increased by 298% and 155% respectively compared with the 5 year mean. The number of overseas acquired cases in 2012 is likely to be the largest on record, with an average of 144 cases per month during the first 7 months of the year. More than half of all dengue cases with a known country of acquisition between 1999 and July 2012 were acquired in Indonesia. In Western Australia in 2010 and 2011, more than 80% of cases acquired in Indonesia were acquired in Bali and the trend has continued into 2012.1 While the frequency of travel by Australians to Indonesia has steadily increased since 2000, this does not completely explain the increased number of dengue cases in returning travellers. The relative risk of dengue in travellers returning from Indonesia between 2000 and 2011 compared with all other destinations was 8.3 (95% confidence interval 7.9-8.9).

Australia's notifiable disease status, 2010: annual report of the National Notifiable Diseases Surveillance System.

In 2010, 65 diseases and conditions were nationally notifiable in Australia. States and territories reported a total of 209,079 notifications of communicable diseases to the National Notifiable Diseases Surveillance System, a decrease of 12% on the number of notifications in 2009. This decrease was largely due to a reduction of influenza compared with the influenza A(H1N1) pandemic 2009. In 2010, the most frequently notified diseases were sexually transmissible infections (86,620 notifications, 41.4% of total notifications), vaccine preventable diseases (61,964 notifications, 29.6% of total notifications), and gastrointestinal diseases (31,548 notifications, 15.1% of total notifications). There were 18,302 notifications of bloodborne diseases; 8,244 notifications of vectorborne diseases; 1,866 notifications of other bacterial infections; 532 notifications of zoonoses and 3 notifications of quarantinable diseases.

Epidemiology of Shiga toxin producing Escherichia coli in Australia, 2000-2010.

BACKGROUND: Shiga toxin-producing Escherichia coli (STEC) are an important cause of gastroenteritis in Australia and worldwide and can also result in serious sequelae such as haemolytic uraemic syndrome (HUS). In this paper we describe the epidemiology of STEC in Australia using the latest available data. METHODS: National and state notifications data, as well as data on serotypes, hospitalizations, mortality and outbreaks were examined. RESULTS: For the 11 year period 2000 to 2010, the overall annual Australian rate of all notified STEC illness was 0.4 cases per 100,000 per year. In total, there were 822 STEC infections notified in Australia over this period, with a low of 1 notification in the Australian Capital Territory (corresponding to a rate of 0.03 cases per 100,000/year) and a high of 413 notifications in South Australia (corresponding to a rate of 2.4 cases per 100,000/year), the state with the most comprehensive surveillance for STEC infection in the country. Nationally, 71.2% (504/708) of STEC infections underwent serotype testing between 2001 and 2009, and of these, 58.0% (225/388) were found to be O157 strains, with O111 (13.7%) and O26 (11.1%) strains also commonly associated with STEC infections. The notification rate for STEC O157 infections Australia wide between 2001-2009 was 0.12 cases per 100,000 per year. Over the same 9 year period there were 11 outbreaks caused by STEC, with these outbreaks generally being small in size and caused by a variety of serogroups. The overall annual rate of notified HUS in Australia between 2000 and 2010 was 0.07 cases per 100,000 per year. Both STEC infections and HUS cases showed a similar seasonal distribution, with a larger proportion of reported cases occurring in the summer months of December to February. CONCLUSIONS: STEC infections in Australia have remained fairly steady over the past 11 years. Overall, the incidence and burden of disease due to STEC and HUS in Australia appears comparable or lower than similar developed countries.

A multistate outbreak of hepatitis A associated with semidried tomatoes in Australia, 2009.

BACKGROUND: A large outbreak of hepatitis A affected individuals in several Australian states in 2009, resulting in a 2-fold increase in cases reported to state health departments compared with 2008. Two peaks of infection occurred (April-May and September-November), with surveillance data suggesting locally acquired infections from a widely distributed food product. METHODS: Two case-control studies were completed. Intensive product trace-back and food sampling was undertaken. Genotyping was conducted on virus isolates from patient serum and food samples. Control measures included prophylaxis for close contacts, public health warnings, an order by the chief health officer under the Victorian Food Act 1984, and trade-level recalls on implicated batches of semidried tomatoes. RESULTS: A multijurisdictional case-control study in April-May found an association between illness and consumption of semidried tomatoes (odds ratio [OR], 3.0; 95% CI 1.4-6.7). A second case-control study conducted in Victoria in October-November also implicated semidried tomatoes as being associated with illness (OR, 10.3; 95% CI, 4.7-22.7). Hepatitis A RNA was detected in 22 samples of semidried tomatoes. Hepatitis A virus genotype IB was identified in 144 of 153 (94%) patients tested from 2009, and partial sequence analysis showed complete identity with an isolate found in a sample of semidried tomatoes. CONCLUSIONS: The results of both case-control studies and food testing implicated the novel vehicle of semidried tomatoes as the cause of this hepatitis A outbreak. The outbreak was extensive and sustained despite public health interventions, the design and implementation of which were complicated by limitations in food testing capability and complex supply chains.

Australia's notifiable disease status, 2009: annual report of the National Notifiable Diseases Surveillance System.

In 2009, 65 diseases and conditions were nationally notifiable in Australia. States and territories reported a total of 236,291 notifications of communicable diseases to the National Notifiable Diseases Surveillance System, an increase of 48% on the number of notifications in 2008. This increase was largely due to cases of influenza A(H1N1) pandemic 2009. In 2009, the most frequently notified diseases were vaccine preventable diseases (101,627 notifications, 43% of total notifications), sexually transmissible infections (73,399 notifications, 31% of total notifications), and gastrointestinal diseases (31,697 notifications, 13% of total notifications). There were 18,861 notifications of bloodborne diseases; 8,232 notifications of vectorborne diseases; 1,919 notifications of other bacterial infections; 552 notifications of zoonoses and 4 notifications of quarantinable diseases.

Australia's notifiable disease status, 2008: annual report of the National Notifiable Diseases Surveillance System.

In 2008, 65 communicable diseases and conditions were nationally notifiable in Australia. States and territories reported a total of 160,508 notifications of communicable diseases to the National Notifiable Diseases Surveillance System, an increase of 9% on the number of notifications in 2007. In 2008, the most frequently notified diseases were sexually transmissible infections (69,459 notifications, 43% of total notifications), vaccine preventable diseases (34,225 notifications, 21% of total notifications) and gastrointestinal diseases (27,308 notifications, 17% of total notifications). There were 18,207 notifications of bloodborne diseases; 8,876 notifications of vectorborne diseases; 1,796 notifications of other bacterial infections; 633 notifications of zoonoses and 4 notifications of quarantinable diseases.

Australia's notifiable disease status, 2007: annual report of the National Notifiable Diseases Surveillance System.

In 2007, 69 diseases and conditions were nationally notifiable in Australia. States and territories reported a total of 146,991 notifications of communicable diseases to the National Notifiable Diseases Surveillance System, an increase of 5% on the number of notifications in 2006. In 2007, the most frequently notified diseases were sexually transmissible infections (62,474 notifications, 43% of total notifications), gastrointestinal diseases (30,325 notifications, 21% of total notifications) and vaccine preventable diseases (25,347 notifications, 17% of total notifications). There were 19,570 notifications of bloodborne diseases; 6,823 notifications of vectorborne diseases; 1,762 notifications of other bacterial infections; 687 notifications of zoonoses and 3 notifications of quarantinable diseases.