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Introduction | Methods | Results - Part 1 | Appendices | Acknowledgements and abbreviations| References
Results part 2: Bloodborne diseases | Gastrointestinal | Quarantinable | Sexually transmissible | Vaccine preventable | Vectorborne | Zoonoses | Other bacterial infections
Results - Part 3
Gastrointestinal diseases
Overview
In 2014, gastrointestinal diseases notified to NNDSS and discussed in this section were: botulism, campylobacteriosis, cryptosporidiosis, haemolytic uraemic syndrome (HUS), hepatitis A, hepatitis E, listeriosis, salmonellosis, shigellosis, Shiga toxin-producing Escherichia coli (STEC) infections and typhoid fever.
Overall notified cases of gastrointestinal diseases increased by 24%, from to 32,535 in 2013 to 40,367 in 2014. Notifications for campylobacteriosis, salmonellosis, and shigellosis were at the highest levels since NNDSS records began in 1991. It should be noted that nucleic acid-based testing methods were introduced by a number of diagnostic laboratories around the country from late 2013 onwards. Whilst these tests may have increased sensitivity compared with traditional techniques, such as culture, the effect on notifications has not been quantified.
Surveillance systems overview
The Australian Government established OzFoodNet—Australia’s enhanced foodborne disease surveillance system—in 2000 as a collaborative network of epidemiologists and microbiologists who conduct enhanced surveillance, epidemiological outbreak investigations and applied research into foodborne disease across Australia. OzFoodNet’s mission is to apply concentrated effort at the national level to investigate and understand foodborne disease, to describe its epidemiology more effectively and to identify ways to minimise foodborne illness in Australia. The data and results summarised in the following sections will be reported in more detail in the OzFoodNet annual report 2014.
Botulism
In 2014, there was 1 case of botulism notified to NNDSS.
Botulism is a rare but extremely serious intoxication resulting from toxins produced by Clostridium botulinum (commonly toxin types A, B and E). Four forms of botulism are recognised; infant, foodborne, wound and adult intestinal toxaemia.22
Epidemiological situation in 2014
There was 1 case of infant botulism notified by Queensland in 2014. C. botulinum toxin type B gene was detected in the stools by polymerase chain reaction (PCR) and toxin type B was confirmed using a mouse bioassay. No source of infection was identified.
Campylobacteriosis
In 2014, 19,931 cases of campylobacteriosis were notified to the NNDSS.
Campylobacteriosis was the most frequently notified enteric infection in 2014.
The bacterium Campylobacter is a common cause of foodborne illness (campylobacteriosis) in humans. The severity of this illness varies and is characterised by diarrhoea (often bloody), abdominal pain, fever, nausea and or vomiting.22 Campylobacteriosis is notifiable in all Australian states and territories except New South Wales.
Epidemiological situation in 2014
There were 19,931 notified cases of campylobacteriosis in 2014 making it the most frequently notified enteric infection (124.9 per 100,000 not including New South Wales). This was a 36% increase on the number of notifications received for 2013 (n=14,692) (Figure 15) and a 19% increase on the 5-year mean (n=16,237) (Table 6). The number of notified cases for 2014 was the highest recorded in NNDSS since 1991, and exceeded 2 standard deviations of the previous 5-year mean (2009 to 2013) by more than 1,300 notifications.
Geographical distribution
Notification rates ranged from 107.0 per 100,000 in South Australia to 181.5 per 100,000 in Tasmania; the Tasmanian rate was approximately 1.5 times higher than the national rate (124.9 per 100,000) (Table 5).
Age and sex distribution
Campylobacteriosis was most frequently notified among the 0–4 years age group for both males (241.9 per 100,000) and females (177.2 per 100,000). The median age of notified cases was 36 years (range 0 to 101 years) and 54% (10,811/19,896) where sex was known were male. Notification rates were highest among males in all age groups (Figure 16).
Cryptosporidiosis
In 2014, 2,405 cases of cryptosporidiosis were notified to the NNDSS.
Cryptosporidiosis is a parasitic infection characterised by abdominal cramping and usually large-volume watery diarrhoea. Ingesting contaminated water, typically from a recreational source like a community swimming pool or lake is a major risk factor for infection.22
Epidemiological situation in 2014
There were 2,405 notified cases of cryptosporidiosis in 2014 (10.2 per 100,000). This represents a 37% decrease on the number of notifications received for 2013 (n=3,846) and a 19% decrease on the 5-year mean (n=2,982) (Figure 17).
Geographical distribution
Notification rates ranged from 5.6 per 100,000 in New South Wales to 35.6 per 100,000 in the Northern Territory; the Northern Territory rate was 3.5 times higher than the national rate (10.2 per 100,000) (Table 5).
Age and sex distribution
In 2014, notified cases for cryptosporidiosis, for which age was reported, were most frequent among the 0–4 years age group (31%, 732/2,403). The median age of notified cases was 18 years (range 0 to 92 years) and just over half (1,234/2,405) were female (Figure 18).
Haemolytic uraemic syndrome
In 2014, 20 cases of haemolytic uraemic syndrome notified to the NNDSS.
Cases were most frequently notified among the 0–4 years age group.
HUS is a rare but serious illness that is characterised by acute renal impairment; with 50% of patients requiring dialysis and approximately 5% dying.22 Not all diagnoses of HUS are related to enteric pathogens, but Australian cases are commonly associated with STEC infection.36 In 2013, 68% (10/15) of notified HUS cases were positive for STEC.37
Epidemiological situation in 2014
There were 20 notified cases of HUS in 2014 compared with 15 in 2013 and a mean of 14 cases per year between 2009 and 2013.
Geographical distribution
Over half (55%, 11) of notifications were in residents from New South Wales (n=6) and Victoria (n=5).
Age and sex distribution
In 2014, HUS was most frequently notified among the 0–4 years age group (45%, 9) (Figure 19). Half of notified cases were in males (n=10).
Hepatitis A
In 2014, 231 cases of hepatitis A infection notified to the NNDSS.
Overseas travel was the primary risk factor for notified cases.
Hepatitis A is an acute viral infection primarily of the liver, characterised by fever, malaise, anorexia, nausea and abdominal discomfort followed by jaundice. The disease varies from a mild illness to a severely disabling disease lasting several months. Infection is usually spread from person to person via the faecal-oral route but can also be foodborne or waterborne.22
Epidemiological situation in 2014
There were 231 notified cases of hepatitis A infection in 2014 (1.0 per 100,000). This was a 22% increase on the number of notified cases in 2013 (n=190), and a 13% decrease on the 5-year mean (n=266). The historical mean reflects the impact of a 2009–2010 outbreak of hepatitis A associated with the consumption of semi-dried tomatoes (Figure 20).38
Geographical distribution
Two-thirds (66%, 153/231) of notifications were in residents from New South Wales (n=83) and Victoria (n=70).
Age and sex distribution
Hepatitis A infection was most frequently notified among the 5–9 years age group (14%, 32) in 2014 (Figure 21). The median age of notified cases was 23 years (range 1 to 76 years), and 58% (134) of all cases were male.
Indigenous status
Indigenous status was known for 96% (222) of notified cases of hepatitis A. Of these, 4 were identified as being Indigenous.
Place of acquisition
Overseas travel was the primary risk factor for notified cases (Table 12). In 2014, 80% (184/231) reported overseas travel during their incubation period for hepatitis A infection and were considered to have been overseas acquired. The top 5 countries of acquisition were Fiji (n=30), the Philippines (n=24), India (n=22), Pakistan (n=18) and Indonesia (n=12).
Year | Locally acquired | Overseas acquired | Unknown | Total | |||
---|---|---|---|---|---|---|---|
n | % | n | % | n | % | ||
2009 | 373 | 66 | 139 | 25 | 51 | 9 | 563 |
2010 | 113 | 42 | 147 | 55 | 7 | 3 | 267 |
2011 | 41 | 28 | 103 | 71 | 1 | 1 | 145 |
2012 | 34 | 20 | 122 | 73 | 10 | 6 | 166 |
2013 | 46 | 24 | 134 | 71 | 10 | 5 | 190 |
2014 | 44 | 19 | 184 | 80 | 3 | 1 | 231 |
In 2014, 19% (44) of notified cases were locally acquired. This was similar to 2012 where 24% (46/190) of notified cases were locally acquired (Table 12). A 2009–2010 outbreak associated with the consumption of semi-dried tomatoes contributed to an increase in locally acquired hepatitis A cases in those years.38 Place of acquisition was unknown or not recorded for 3 notified cases.
Hepatitis E
In 2014, 56 cases of hepatitis E infection notified to the NNDSS.
Hepatitis E infection is an acute viral infection primarily of the liver that is transmitted by the faecal-oral route, most often via food or water.22 The infection is usually acquired overseas among travellers to endemic areas.
Epidemiological situation in 2014
There were 56 notified cases of hepatitis E infection in 2014 (0.2 per 100,000). This was a 65% increase on the number of notified cases in 2013 (n=34), and a 60% increase on the 5-year mean (n=35).
Geographical distribution
The majority of notifications were in residents from New South Wales (n=37).
Age and sex distribution
Hepatitis E infection was most frequently notified among the 30–34 years age group (14%, 8) (Figure 22). In 2014, the median age of notified cases was 47 years (range 21 to 77 years), and 55% (31) were male.
Place of acquisition
Hepatitis E in Australia has traditionally been associated with overseas travel. In 2014, 52% of cases (29) reported overseas travel during their incubation period and were considered to have been acquired overseas. Of these, 38% (11/29) reported travel to India. The place of acquisition was unknown for 6 notified cases.
In 2014, 38% (21) of cases were locally acquired, with the majority of these reported in New South Wales residents (n=20). The large number of notified cases among residents from New South Wales can be attributed to a cluster of hepatitis E infection associated with consumption of pork liver pâté at a specific restaurant in that state.39 This was the first documented locally acquired outbreak of hepatitis E in Australia.
Listeriosis
In 2014, 80 cases of listeriosis notified to the NNDSS.
Notifications were highest in the 80+ year age group.
Invasive listeriosis is caused by a bacterial infection that commonly affects the elderly or immunocompromised, and typically occurs among people with serious underlying illnesses. Listeriosis can also affect pregnant women and infect their unborn baby.40 Laboratory-confirmed infections in a mother and her unborn child or neonate are notified separately in the NNDSS.
Epidemiological situation in 2014
There were 80 notified cases of listeriosis in 2014 (0.3 per 100,000), which was a slight increase on the number of notified cases in 2013 (n=76) and the same as the 5-year mean (n=80).
Geographical distribution
Over half (56%, 45) of notifications were in residents from New South Wales (n=23) and Victoria (n=22).
Age and sex distribution
Notifications of listeriosis were highest in the 80 years or over age group (16%, 13/80) (Figure 23), with just over half (51%, 41) of all notified cases being male.
Enhanced surveillance datasets
In 2010, OzFoodNet started collecting enhanced surveillance data on all notified cases of listeriosis in Australia. The information collected on cases includes laboratory data collected from the characterisation of Listeria monocytogenes isolates by molecular subtyping methods, and epidemiological data, which includes food consumption histories and clinical data. The overall aim of this enhanced surveillance is to enable timely detection of outbreaks and subsequent public health response.41 Further information on OzFoodNet’s National Enhanced Listeriosis Surveillance System can be found in OzFoodNet annual reports (http://www.ozfoodnet.gov.au/internet/ozfoodnet/publishing.nsf/Content/reports-1).
Salmonellosis (non-typhoidal)
In 2014, 16,358 cases of salmonellosis notified to the NNDSS.
This was the highest number of notifications recorded in NNDSS since 1991.
Salmonellosis is a bacterial disease characterised by the rapid development of symptoms including abdominal pain, fever, diarrhoea, muscle pain, nausea and/or vomiting. People can become infected via faecal-oral transmission, ingesting contaminated food, through animal contact and from environmental exposures. The predominant mode of transmission is contaminated food, mainly of animal origin.22
Epidemiological situation in 2014
There were 16,358 notified cases of salmonellosis in 2014 (69.7 per 100,000). This was a 28% increase on the number of cases reported in 2013 (n=12,785) (Figure 24), and a 42% increase on the 5-year mean (n=11,545). The number of cases for 2014 was the highest recorded in NNDSS since 1991 when this disease became nationally notifiable, beating the previous record in 2013. Additionally, notified cases in 2014 exceeded 2 standard deviations of the previous 5-year mean (2009 to 2013) by more than 2,200 notifications.
Geographical distribution
Notification rates ranged from 48.4 per 100,000 in Tasmania to 186.8 per 100,000 in the Northern Territory (Table 5).
Age and sex distribution
Salmonellosis was most frequently notified among the 0–4 years age group (23%, 3,709/16,355) (Figure 25) where age was recorded, with an age-specific rate of 210.4 per 100,000 population. The median age of notified cases was 27 years (range 0 to 102 years) and just over half (51%, 8,393/16,333) of cases where sex was recorded were female.
Shigellosis
In 2014, 1,051 notified cases of shigellosis to the NNDSS.
Increase in notifications possibly associated with increased in culture-independent diagnostic testing.
Shigellosis is a bacterial disease characterised by acute abdominal pain and fever, small-volume loose stools, vomiting and tenesmus. Shigella is transmitted via the faecal-oral route, either directly (such as male-to-male sexual contact) or indirectly through contaminated food or water.22
Epidemiological situation in 2014
There were 1,051 notified cases of shigellosis in 2014 (4.5 per 100,000). This was a 95% increase on the number of cases in 2013 (n=538) (Figure 26), and a 91% increase on the 5-year mean (n=550). This increase may be associated with the increased use of culture-independent diagnostic testing (CIDT). The current CIDT methods are unable to differentiate between infection with Shigella, which is notifiable, and entero-invasive Escherichia coli, which is not.42
Geographical distribution
Notification rates ranged from 0.4 per 100,000 in Tasmania to 40.5 per 100,000 in the Northern Territory. State and territory rates for 2014 should be interpreted with caution as some jurisdictions require CIDT-positive samples to be confirmed by culture whilst others do not.
Age and sex distribution
Notifications for shigellosis were highest in the 0–4 year age group (13%, 135) (Figure 27). In 2014, the median age of notified cases was 34 years (range 0 to 94 years) and almost two-thirds (65%, 688) were male.
Indigenous status
Information on Indigenous status was available for 81% (853) of shigellosis cases. This proportion varied by state or territory, with Queensland being the only jurisdiction with less than 80% data completeness. Among states and territories with greater than or equal to 80% completeness, the proportion of notified cases who identified as being of Aboriginal and/or Torres Strait Islander origin was 11% (98/875).
Place of acquisition
Thirty-two per cent (333) of notified cases of shigellosis were reported as being acquired overseas. The top 5 countries of acquisition were Indonesia (n=86), India (n=54), Thailand (n=21), Vietnam (n=20) and Cambodia (n=17). The place of acquisition was inadequately described or unknown for half of notifications (51% 530) (Table 13).
Year | Locally acquired | Overseas acquired | Unknown | Total | |||
---|---|---|---|---|---|---|---|
n | % | n | % | n | % | ||
2009 | 227 | 37 | 83 | 13 | 307 | 50 | 617 |
2010 | 164 | 30 | 191 | 35 | 197 | 36 | 552 |
2011 | 152 | 31 | 133 | 27 | 208 | 42 | 493 |
2012 | 141 | 26 | 174 | 32 | 233 | 43 | 548 |
2013 | 137 | 25 | 209 | 39 | 192 | 36 | 538 |
2014 | 188 | 18 | 333 | 32 | 530 | 50 | 1,051 |
Shiga toxin-producing Escherichia coli
In 2014, 116 notified cases of Shiga toxin-producing Escherichia coli infection to the NNDSS.
Shiga toxin-producing Escherichia coli is a common cause of diarrhoeal illness in humans. People can become infected via faecal-oral transmission, ingesting contaminated food, through animal contact and from environmental exposures. Severe illness can progress to HUS. Children under 5 years of age are most frequently diagnosed with infection and are at greatest risk of developing HUS.22
Epidemiological situation in 2014
There were 115 notified cases of STEC in 2014 (0.5 per 100,000). This was a 36% decrease on the number of cases in 2013 (n=180) and similar to the 5-year mean (n=119). A large outbreak (n=57) of STEC infection associated with a Queensland agricultural show contributed to the high number of notifications seen in 2013.43
Geographical distribution
Detection of STEC infection is strongly influenced by jurisdictional practices regarding the screening of stool specimens.41 South Australia continues to test all bloody stools for STEC using PCR and subsequently has the highest notification rate in the country; 2.7 cases per 100,000 compared with between 0.1 and 0.6 cases per 100,000 in other states and territories reporting cases. Additionally, South Australia ceased routinely culturing PCR positive STEC samples in 2014. The differences in testing practices among states and territories render comparison of notification data by jurisdiction and over time invalid.
Age and sex distribution
Notifications of STEC were highest in the 20–24 years age group (13%, 15/115) (Figure 28). In 2014, the median age of notified cases was 33 years (range 0 to 88 years) and 60% (69) of notified cases were female.
Typhoid fever
In 2014, 119 notified cases of typhoid to the NNDSS.
92% of cases were acquired overseas.
Typhoid is a bacterial disease caused by Salmonella enterica serotype Typhi. Symptoms include sustained fever, marked headache, malaise and constipation more often than diarrhoea in adults. The transmission mode is the same as for salmonellosis, however, typhoid differs in that humans are the reservoir for the bacterium.22
Epidemiological situation in 2014
There were 119 notified cases of typhoid in 2014 (0.5 per 100,000). This was a 22% decrease on the number of cases in 2013 (n=152) (Figure 29) and similar to the 5-year mean (n=125).
Geographical distribution
Almost two-thirds (62%, 74) of notifications were in residents from New South Wales (n=45) and Victoria (n=29).
Age and sex distribution
Typhoid was most frequently notified among the 20–24 years age group (17%, 20) (Figure 30). The median age of notified cases was 22 years (range 1 to 77 years), and 61% (73) were male.
Place of acquisition
As in previous years, overseas travel was the primary risk factor for notified cases. In 2014, 92% (109) reported overseas travel during their exposure period and were considered overseas acquired. India continues to be the most frequently reported country of acquisition, accounting for 56% (61/109) of overseas-acquired cases in 2014. Six cases were listed as locally acquired and the place of acquisition was unknown for 4 cases (Table 14).
Year | Locally acquired | Overseas acquired | Unknown | Total | |||
---|---|---|---|---|---|---|---|
n | % | n | % | n | % | ||
2009 | 15 | 13 | 82 | 71 | 18 | 16 | 115 |
2010 | 2 | 2 | 92 | 96 | 2 | 2 | 96 |
2011 | 6 | 4 | 125 | 93 | 4 | 3 | 135 |
2012 | 9 | 7 | 109 | 87 | 7 | 6 | 125 |
2013 | 8 | 5 | 141 | 93 | 3 | 2 | 152 |
2014 | 6 | 5 | 109 | 92 | 4 | 3 | 119 |
Quarantinable diseases
Human diseases covered by the Quarantine Act 1908, and notifiable in Australia and to the WHO in 2014 were cholera, plague, rabies, yellow fever, smallpox, highly pathogenic avian influenza in humans (HPAIH), severe acute respiratory syndrome (SARS) and 4 viral haemorrhagic fevers (Ebola, Marburg, Lassa and Crimean–Congo). These diseases are of international public health significance.
Travellers are advised to seek information on the risk of contracting these diseases at their destinations and to take appropriate measures. More information on quarantinable diseases and travel health can be found on the Travel Health Information web site (www.health.gov.au/internet/main/publishing.nsf/Content/health-pubhlth-strateg-quaranti-index.htm) and on the Smartraveller web site (www.smartraveller.gov.au/).
There were no cases of plague, rabies, smallpox, SARS, HPAIH or viral haemorrhagic fevers reported in Australia in 2014. While there were 2 cases of overseas-acquired cholera in 2014, Australia remains free of all the listed quarantinable diseases (Table 15).
Disease | Status | Date of last record and notes |
---|---|---|
Cholera | Free | Small number of cases reported annually related to overseas travel. Very rare instances of local acquisition as described under the section '˜Cholera'. |
Plague | Free | Last case recorded in Australia in 192344 |
Rabies | Free | Last case (overseas acquired) recorded in Australia in 199045 |
Smallpox | Free | Last case recorded in Australia in 1938, last case world-wide in 1977, declared eradicated by the World Health Organization 198046,47 |
Yellow fever | Free | Two cases in 2011 were the first recorded, related to overseas travel37 |
SARS | Free | Last case recorded in Australia in 200348 |
HPAIH | Free | No cases recorded49 |
Viral haemorrhagic fevers | ||
Ebola | Free | No cases recorded |
Marburg | Free | No cases recorded |
Lassa | Free | No cases recorded |
Crimean–Congo | Free | No cases recorded |
Cholera
In 2014, 2 cases of cholera notified to the NNDSS.
Cholera is an infection of the digestive tract (or gut) caused by certain strains of the bacterium Vibrio cholerae that produce toxins (poisons) and is most commonly acquired in parts of Africa, Asia, South America, the Middle East and the Pacific islands. V. cholerae is found in the faeces of infected people, and is spread by drinking contaminated water, eating food washed with contaminated water or prepared with soiled hands or eating fish or shellfish caught in contaminated water. Person-to-person spread of cholera is less common. Most people do not develop symptoms or have only mild illness but a small proportion of people will develop severe symptoms. Symptoms typically start between 2 hours and 5 days (usually 2 to 3 days) after ingesting the bacteria. Symptoms can include characteristic ‘rice water’ faeces (profuse, watery diarrhoea), nausea and vomiting, signs of dehydration, such as weakness, lethargy and muscle cramps. Only toxigenic V. cholerae o1 or o139 are notifiable in Australia.
Epidemiological situation in 2014
In 2014, there were 2 notifications of cholera in Australia. The following details are available about the relevant exposures or place of acquisition for the 2 cases in 2014:
- Case 1 was a 1-year-old female who acquired the infection whilst travelling in India;
- Case 2 was a 63-year-old female who was an international visitor and had acquired the infection in India;
- These cases both notified by Victoria, but were not known to have been linked.
There were 21 cases of cholera in total in Australia between 2009 and 2013. All cases of cholera reported since the commencement of the NNDSS in 1991 to 2013 have been acquired outside Australia except for 1 case of laboratory-acquired cholera in 1996,50 3 cases in 2006 linked to imported whitebait51 and 1 laboratory-acquired case in 2013.37
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