Results - Part 2 continued

Gastrointestinal diseases

Overview

In 2013, 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 from 31,155 in 2012 to 32,535 in 2013. Notifications for salmonellosis, typhoid fever and STEC were at the highest levels since NNDSS records began in 1991.

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 2013.

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Botulism

• 4 cases of botulism were notified in 2013.

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.²¹

Epidemiological situation in 2013

There were 4 notified cases of botulism in 2013; all four were infant botulism but no links between them were identified. This compares with no notified cases in 2012 and 2 infant botulism cases in 2011.

Campylobacteriosis

• 14,698 cases of campylobacteriosis were notified in 2013.
• This was the most frequently notified enteric infection in 2013.

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.²¹ Campylobacteriosis is notifiable in all Australian states and territories except New South Wales.

Epidemiological situation in 2013

There were 14,698 notified cases of campylobacteriosis in 2013 making it the most frequently notified enteric infection (93.5 per 100,000 not including New South Wales). This was a decrease of 6.1% on the number of notifications received for 2012 (n=15,655) and a 10.4% decrease on the 5-year mean (n=16,407). Notification rates ranged from 76.5 per 100,000 in Western Australia to 135.6 per 100,000 in Tasmania.

Age and sex distribution

Campylobacteriosis was most frequently notified among the 0–4 age group for both males (183.3 per 100,000) and females (131.3 per 100,000). The median age of notified cases was 28 years and 54.8% (n= 8,056) were male. Notification rates were highest among males in nearly all age groups (Figure 14).

Figure 14: Notification rate for campylobacteriosis, Australia, 2013, by age group and sex

Text version of Figure 14 (TXT 1 KB)

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Cryptosporidiosis

• 3,846 cases of cryptosporidiosis were notified in 2013.
• There was 1 outbreak in New South Wales.

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.²¹

Epidemiological situation in 2013

There were 3,846 notified cases of cryptosporidiosis in 2013 (16.6 per 100,000). This represents a 23.1% increase over the 3,124 cases reported in 2012 and a 47.2% increase over the 5-year mean of 2,612 cases. Notification rates ranged from 8.1 per 100,000 in South Australia to 36.9 per 100,000 in the Northern Territory.

Age and sex distribution

In 2013, notified cases of cryptosporidiosis were most frequently reported among the 0–4 years age group (36.6%, n=1,407) and of these, 58.8% (n=828) were male. This was consistent with 2012 figures when notifications of cryptosporidiosis were also most frequent in the 0–4 years age group (45.8%, n=1,437), and the majority of these were male (59.0%, n=848).

Outbreaks

An outbreak of cryptosporidiosis occurred in New South Wales in the 1st quarter of 2013, associated with community swimming pools across New South Wales and particularly in north-eastern Sydney.³¹

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Haemolytic uraemic syndrome

• 15 cases of haemolytic uraemic syndrome were notified in 2013.
• 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 about 5% dying.²¹ Not all diagnoses of HUS are related to enteric pathogens, but Australian cases are commonly associated with STEC infection.³² In 2013, 66.7% (10/15) of HUS cases were positive for STEC.

Epidemiological situation in 2013

There were 15 notified cases of HUS in 2013 compared with 20 in 2012 and a mean of 17.2 cases per year between 2008 and 2012. Five of these cases were associated with STEC.

Age and sex distribution

In 2013, HUS was most frequently notified among the 0–4 years age group (27%, n=4), with a median age of 18 years (range 1–82 years). One-third of notified cases were in males (n=5) compared with 70% (n=14) in 2012.

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Hepatitis A

• 189 cases of hepatitis A were notified in 2013.
• 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.²¹

Epidemiological situation in 2013

There were 189 notified cases of hepatitis A in 2013 (0.8 per 100,000). This was a 13.8% increase on the number of cases in 2012 (n=166), and a 33.3% decrease on the 5-year mean (n=283.4). The historical mean reflects the impact of a 2009–2010 outbreak of hepatitis A associated with the consumption of semi-dried tomatoes (Figure 15).

Figure 15: Notification rate for hepatitis A, Australia, 2008 to 2013

Text version of Figure 15 (TXT 1 KB)

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Age and sex distribution

Hepatitis A was most frequently notified among the 5–9 years age group (n=23) in 2013. The median age of notified cases was 25 years (range 1–79 years), and 59.3% (n=112) of all cases were male compared with 48% in 2012 (n=80).

Indigenous status

Indigenous status was known for 95.2% (n=180) of cases of hepatitis A. Of these, 3 were identified as being Indigenous.

Place of acquisition

Overseas travel was the primary risk factor for notified cases. In 2013, 61.4% (n=116) reported overseas travel during their incubation period for hepatitis A and were considered to have been overseas acquired. Travel to India, the Philippines and Vanuatu were most frequently reported.

In 2013, 20.6% (n=39) of notified cases were locally acquired. This was an increase from 2012 where 18% (n=30) 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.³³

Table 12: Notified cases of hepatitis A, Australia, 2008 to 2013, by place of acquisition

Year	Locally acquired		Overseas acquired		Unknown		Total
	n	%	n	%	n	%
2008	64	23	121	44	91	33	276
2009	304	54	184	33	75	13	563
2010	112	42	144	54	11	4	267
2011	39	27	97	67	9	6	145
2012	30	18	111	67	25	15	166
2013	39	21	116	61	34	18	189

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Hepatitis E

• 31 cases of hepatitis E were notified in 2013.
• The first 3 confirmed locally acquired infections occurred in 2013.

Hepatitis E is an acute viral infection primarily of the liver that is transmitted by the faecal-oral route, most often via food or water. ²¹ The infection is usually acquired overseas among travellers to endemic areas.

Epidemiological situation in 2013

There were 31 notified cases of hepatitis E in 2013, compared with a 5-year mean of 38 cases.

Age and sex distribution

Hepatitis E was most frequently notified among the 25–39 years age group (n=8), the median age of cases was 32 years (range 4–72 years), and 68% (n=21) of total cases were male.

Place of acquisition

Hepatitis E in Australia has traditionally been associated with overseas travel. In 2013, 87% of cases (n=27) reported overseas travel during their incubation period and were considered to have been acquired overseas, of these, 41% (n=11) reported travel to India. The first 3 confirmed cases of locally acquired hepatitis E occurred in New South Wales in the last quarter of 2013.

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Listeriosis

• 76 cases of listeriosis were notified in 2013.
• Notified cases were highest in the 80+ years 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. Laboratory-confirmed infections in a mother and her unborn child or neonate are notified separately in the NNDSS.

Epidemiological situation in 2013

There were 76 notified cases of invasive Listeria monocytogenes infection in 2013 (0.3 per 100,000) compared with a 5-year mean of 78.8 cases.

Age and sex distribution

Notifications for listeriosis were highest in the 80+ years age group (21%, n=16), with 53% (n=40) of all notified cases being female (Figure 16).

Figure 16: Notified cases of listeriosis, Australia, 2013, by age group and sex

Text version of Figure 16 (TXT 1 KB)

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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 the characterisation of Listeria monocytogenes isolates by molecular subtyping methods, food histories and exposure data. The overall aim of this enhanced surveillance is to enable timely detection of outbreaks and subsequent public health response.³² Further information on OzFoodNet’s enhanced Listeria surveillance system can be found in OzFoodNet annual reports (http://www.ozfoodnet.gov.au/internet/ozfoodnet/publishing.nsf/Content/reports-1).

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Salmonellosis (non-typhoidal)

• 12,791 cases of salmonellosis were notified in 2013.
• Cases were most frequently notified among the 0–4 years age group.

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.²¹

Epidemiological situation in 2013

There were 12,791 notified cases of salmonellosis in 2013 (55.3 per 100,000) with the number of cases being 20.1% higher than the 5-year mean of 10,649 cases. This represents a 13.5% increase in cases compared with 2012 (n=11,265). The number of cases for 2013 was the highest recorded in NNDSS since 1991. Rates ranged from 46.6 per 100,000 in New South Wales to 159.6 per 100,000 in the Northern Territory.

Age and sex distribution

Salmonellosis was most frequently notified among the 0–4 years age group (23.6%, n=3,015), the median age of notified cases was 27 years (range 0–93 years) and 50.5% (n=6,461) of cases where sex was stated were females (Figure 17).

Figure 17: Notification rate for salmonellosis, Australia, 2013, by age group and sex*

* Sex and/or age were not reported for 39 cases.

Text version of Figure 17 (TXT 1 KB)

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Shigellosis

• 556 cases of shigellosis were notified in 2013.
• 38% of notified cases were acquired overseas.

Epidemiological situation in 2013

There were 556 notified cases of shigellosis in 2013 (2.4 per 100,000), which was fewer than the 5-year mean of 608 cases. Notification rates ranged from 0.6 per 100,000 in Tasmania to 44.8 per 100,000 in the Northern Territory.

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.²¹

Age and sex distribution

Notifications for shigellosis were highest in the 0–4 years age group (19.8%, n=110). In 2013, the median age of notified cases was 29 years (range 0–87 years) and 51.5% (n=286) were male.

Indigenous status

Information on Indigenous status was available for 90.6% (n=504) of shigellosis cases. This proportion varied by state or territory, with Queensland and Tasmania being less than 80% complete. Among states and territories with greater than 80% completeness, the proportion of notified cases who identified as being of Aboriginal or Torres Strait Islander origin was 23.9% (115/481).

Place of acquisition

Thirty-nine per cent (n=216) of notified cases of shigellosis were reported as being acquired overseas. The most frequently reported countries of acquisition for imported cases were India (22.2%, n=48) and Indonesia (17.3%, n=38). The place of acquisition for 35.6% (n=198) was inadequately described or unknown, down from 64% (n=530) in 2008 (Table 13).

Table 13 Notified cases of shigellosis, Australia, 2008 to 2013, by place of acquisition

Year notified	Locally acquired		Overseas acquired		Unknown		Total
	n	%	n	%	n	%
2008	207	25	93	11	530	64	830
2009	205	33	55	9	356	58	616
2010	153	28	163	30	236	43	552
2011	152	31	133	27	208	42	493
2012	137	25	173	32	238	43	548
2013	142	26	216	39	198	36	556

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Shiga toxin-producing Escherichia coli

• 180 cases of Shiga toxin-producing Escherichia coli were notified in 2013.

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.²¹

Epidemiological situation in 2013

There were 180 notified cases of STEC in 2013 (0.8 per 100,000) compared with a 5-year mean of 102 cases. Of these, 5 cases developed HUS. Detection of STEC infection is strongly influenced by jurisdictional practices regarding the screening of stool specimens.³² South Australia continues to test all bloody stools for STEC using polymerase chain reaction (PCR) and subsequently has the highest notification rate in the country (3.2 cases per 100,000 compared with between 0.2 and 1.8 cases per 100,000 in other states and territories reporting cases). In addition, Victoria notified cases of HUS caused by STEC as HUS only, whereas all other jurisdictions notify each case as both organisms. These differences in testing practice mean that meaningful comparison of notification data by jurisdiction and over time are not valid.

Age and sex distribution

In 2013, 53% (n=95) of notified STEC cases were female. The median age of notified cases was 23 years (range 0–91 years).

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Typhoid

• 150 cases of typhoid were notified in 2013.
• 94% of notified 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.²¹

Epidemiological situation in 2013

There were 150 notified cases of typhoid in 2013 (0.6 per 100,000), compared with the 5-year mean of 115.2 cases. This was a 21% increase on the number of cases in 2012 (n=124).

Age and sex distribution

Typhoid was most frequently notified among the 10–14 years age group (15%, n=22), the median age of notified cases was 23 years (range 1–58 years), and 51% (n=77) were female.

Place of acquisition

As in previous years, overseas travel was the primary risk factor for notified cases. In 2013, 94% (n=141) 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 61% (n=86) of overseas-acquired cases in 2013. Eight cases (5%) were locally acquired and the place of acquisition was unknown for 1 case (1%).

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Quarantinable diseases

Human diseases covered by the Quarantine Act 1908, and notifiable in Australia and to the WHO in 2013 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 from the Smartraveller web site (www.smartraveller.gov.au/).

There were no cases of plague, rabies, smallpox, yellow fever, SARS, HPAIH or viral haemorrhagic fevers reported in Australia in 2013. While there were 3 cases of cholera, Australia remains free of all the listed quarantinable diseases (Table 14).

Table 14: Australia’s status for human quarantinable diseases, 2013

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 192334
Rabies	Free	Last case (overseas acquired) recorded in Australia in 199035
Smallpox	Free	Last case recorded in Australia in 1938, last case worldwide in 1977, declared eradicated by the World Health Organization 198036,37
Yellow fever	Free	Two cases in 2011 were the first recorded, related to overseas travel38
SARS	Free	Last case recorded in Australia in 200339
HPAIH	Free	No cases recorded40
Viral haemorrhagic fevers
Ebola	Free	No cases recorded
Marburg	Free	No cases recorded
Lassa	Free	No cases recorded
Crimean–Congo	Free	No cases recorded

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Cholera

• 3 cases of cholera were notified in 2013.

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 2–3 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 2013

In 2013, there were 3 notifications of cholera in Australia. There were 23 cases of cholera in total in Australia between 2008 and 2012. The following details are available about the relevant exposures or place of acquisition for the 3 cases in 2013:

• all cases were aged between 20 and 40 years, 2 cases were male and one was female;
• two were reported by New South Wales and one by Victoria;
• the country of acquisition was reported as Bangladesh (2 cases) and Australia;
• the case acquired in Australia was laboratory-acquired.

All cases of cholera reported since the commencement of the NNDSS in 1991 to 2012 have been acquired outside Australia except for 1 case of laboratory-acquired cholera in 1996⁴¹ and 3 cases in 2006 linked to imported whitebait.⁴²

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