Delivering a Healthy WA
Disease WAtch

December 2013, Volume 17, issue 4

Full issue

Returned travellers from Bali behind spike in chikungunya virus infections

Chikungunya virus infection is a mosquito-borne acute illness caused by the chikungunya virus, a member of the Alphavirus group, which also includes Ross River and Barmah Forest viruses. Chikungunya virus is endemic in many tropical regions of the world, reflecting the distribution of Aedes aegypti and A. albopictus mosquitoes, the same vectors that transmit dengue viruses. Chikungunya virus is not endemic in Australia, although there is potential for transmission in northern Queensland (A. aegypti) and the Torres Strait Islands (both species), where these mosquitoes are established.

From the early 2000s, major outbreaks of chikungunya virus infection were reported in Southeast Asian, South Asian and Indian Ocean island countries, including Indonesia, Malaysia, Reunion, Seychelles, and India. An increased number of chickungunya outbreaks worldwide has resulted in numerous reports of imported infections among travellers recently returned from these and other countries.

Chikungunya virus infection became a notifiable disease in Western Australia in May 2008. Between 2008 and 2012, an average of 6 chikungunya cases were notified per year (range: 2–10 cases), with infection acquired in a number of countries, mostly in Southeast Asia (Figure 1).

This year, however, there has been a dramatic increase in notifications of chikungunya virus disease, with 51 cases reported to September. This increase is attributable wholly to an increase in the number of cases acquired in Bali, Indonesia. Of the 51 cases notified to date, most were females (70%, n=58) and the median age was 45 years (range: 10–74 years). The vast majority of cases (92%, n=47) reported recent travel to Indonesia, and among these, 94% (n=44) had been to Bali. The remaining 4 chikungunya cases in 2013 acquired their infections in Papua New Guinea (n=2), Singapore (n=1) and an unspecified location in Southeast Asia (n=1). Official data on the incidence of chikungunya virus in Bali are lacking, however, one local newspaper report indicated an increase in transmission of the disease in early 2013.

Chikungunya virus infection should be considered among travellers returning from Bali and other endemic regions with febrile illnesses. Signs and symptoms of chikungunya virus infection include fever, rash and arthralgia affecting multiple joints, as well as headache, nausea, vomiting and conjunctivitis. Typically, the fever lasts for 2 days and ends abruptly. Other symptoms, however, last for several days, and joint pains may persist for months. The incubation period ranges from 2 to 12 days but is usually 3 to 7 days. The differential diagnosis in a returned traveller includes measles, rubella, leptospirosis, scrub typhus malaria, typhoid fever and other arthropod-borne viral infections, such as dengue virus. Serological and in some instances polymerase chain reaction (PCR) testing for chikungunya virus infection is available via WA pathology laboratories.

Given the large number of Western Australians who visit Bali, doctors should advise any patient planning travel to the island – or other endemic areas – of the risks of mosquito-borne diseases, particularly dengue fever and chikungunya virus infection.

This advice should include taking precautions to prevent mosquito bites by applying insect repellent, wearing long, light-coloured, loose-fitting clothing and sleeping in screened accommodation. It should also highlight that the mosquitoes that transmit chikungunya and dengue viruses bite during the day and prefer shady, indoor locations.

* 1 January to 30 September 2013

Figure 1 – Notifications of chikungunya virus infection in Western Australia, by country of acquisition and year, May 2008 to September 2013

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Community-associated Clostridium difficile infection – an emerging issue

Enhanced surveillance by the Healthcare Associated Infection Unit (HAIU) suggests community-associated Clostridium difficile infection (CA-CDI) may be a growing concern.

Clostridium difficile infection (CDI) has traditionally been considered almost exclusively a nosocomial or ‘healthcare-associated’ infection (HAI)1. Recent literature, however, suggests that a changing epidemiology is emerging, with an increase in community cases being observed, and disease occurring in individuals who lack any of the classical risk factors of being in an older age group, history of antibiotic use, and recent hospitalisation.1

Further research is being undertaken to quantify the burden of CDI in the community.

Clostridium difficile is a spore-forming, Gram-positive, anaerobic bacillus, which is a frequent cause of antibiotic-associated diarrhoea, especially among hospitalised patients3.The spectrum of disease caused by CDI can range from mild diarrhoea to severe conditions such as fulminant colitis and toxic megacolon which can result in death3,4.

Western Australian rates of hospital-identified CDI (HI-CDI) are reported by the Department of Health via Healthcare Infection Surveillance WA (HISWA). The latest data show an increase in aggregate rates since reporting commenced in January 2010 (Figure 1). HI-CDI include all cases identified at a healthcare facility, including inpatients, outpatients and those attending the emergency department. This definition does not differentiate between infections acquired in hospital and those acquired in the community, but rather reflects the total burden of cases identified at WA healthcare facilities.

Figure 1 – Hospital-identified Clostridium difficile infection rates, by hospital group

Enhanced surveillance undertaken by the HAIU recently, separated HI-CDI into healthcare associated and community associated cases, using the Australian Commission on Safety and Quality in Healthcare (ACSQHC) definition 5. The enhanced surveillance data confirmed that CA-CDI represented a significant proportion of CDI identified by WA hospitals (Figure 2). The true burden of CA-CDI is unknown because the data did not include cases identified in general practice. As such, HI-CDI identifies only a fraction of the true CA-CDI burden.

Further research is underway to estimate the total burden of CA-CDI in Western Australia. As the data suggest that CA-CDI may be a growing concern, C. difficile should be considered a possible cause of infectious diarrhoea in patients presenting to general practice, especially those with a recent history of antibiotic exposure.

Figure 2 – Community-associated-Clostridium difficile infection (CA-CDI) and hospital-associated Clostridium difficile infection (HA-CDI) cases reported to the Hospital Infection Surveillance Western Australia (HISWA), 2010 to 2012

References

  1. Pituch H. Clostridium difficile is no longer just a nosocomial infection or an infection of adults. International Journal of Antimicrobial Agents. 2009;33:S42–S5.
  2. Kuntz JL, Chrischilles EA, Pendergast JF, Herwaldt LA, Polgreen PM. Incidence of and risk factors for community-associated Clostridium difficile infection: a nested case-control study. BMC Infect Dis. 2011;11:194. Epub 2011/07/19.
  3. Barbut F, Petit J-C. Epidemiology of Clostridium difficile-associated infections. Clinical Microbiology Infections. 2001;7:405–10.
  4. Williams OM, Spencer RC. The management of Clostridium difficile infection. British Medical Bulletin. 2009;91(1):87–110.
  5. Australian Commission on Safety and Quality in Healthcare (ACSQHC). Implementation guide for surveillance of Clostridium difficile infection. Consultation Edition. 2011. Commonwealth of Australia: Canberra.

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Texts help monitor safety of influenza vaccine in pregnant women

Pregnant women are at increased risk of serious influenza-related complications, yet nearly 75% go unvaccinated each year in Western Australia.1 Many women cite safety concerns as their reason for non-vaccination.1 In 2013, the Western Australia Department of Health implemented FASTMum (Follow-up and Active Surveillance of Trivalent influenza vaccine in Mums), an active surveillance system which uses text messaging to monitor post-vaccination reactions to the influenza vaccine.

Between March and July 2013, 2,547 women who received an influenza vaccination were sent a text message asking if they had experienced a reaction to the vaccine. Of these, 217 (8.7%) replied “yes” to the text message, indicating they had experienced a post-vaccination reaction. These women were followed up by telephone to obtain information about their reaction. The most common reaction reported was a minor local reaction, such as swelling, redness, or pain at the injection site with 3.5% of women reporting an injection site reaction; 2.7% of women reported a headache, 2.3% nasal congestion, 2.1% fatigue, and 2.0% a fever (Figure 1). Less than 1% of women reported a rash, vomiting, rigors, myalgia, arthralgia, light-headedness, dizziness, or malaise. No serious vaccine-related reactions were reported.

By using mobile phone technology to monitor vaccine safety, the Western Australia Department of Health was also able to monitor the safety of influenza vaccination in pregnant women in near real time. Overall, few pregnant women experienced a reaction to the influenza vaccine and no serious reactions were recorded. These results corroborate previous reports and lend further support to the safety of influenza vaccination in pregnant women.

Figure 1 – Percentage of women reporting a reaction following influenza immunisation, 2013

Reference

  1. Taksdal SE, Mak DB, Joyce S, et al. Predictors of uptake of influenza vaccination in pregnant women in Western Australia. Aust Fam Physician 2013, 42(8), 582–6.

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Insight into influenza vaccine uptake among WA Health staff

Annual influenza vaccination of healthcare workers benefits workers, employers and patients by reducing staff absenteeism and disease transmission within healthcare facilities.

In 2013, a whole-of-WA Health staff influenza vaccination form was introduced that had been formatted to enable digitised scanning into an electronic database. This gave WA Health access to timely information about staff influenza vaccination uptake and enabled it to compare staff influenza vaccine orders with actual use, as a measure of wastage and leakage.

Based on vaccine orders and vaccination forms submitted for data entry, a total of 20,230 influenza vaccines were ordered for staff and 20,906 people received influenza vaccine; 19,784 were WA Health employees and 1,122 were students or volunteers.

The number of WA Health employees eligible for influenza vaccination (based on employee headcount at the mid-point of the influenza vaccination season) was obtained from the Workforce Modelling and Data Branch of Performance Activity and Quality Division.

Overall, vaccination coverage among WA Health employees was 43.5%, varying by region (from 34.2% in the Kimberley to 82.8% in the Pilbara), and by occupational group (from 32.6% in administration/clerical staff to 43.7% in nursing staff) (see tables 1 and 2 below).

Table 1 – Vaccination coverage by health service/region

Health Service/Region

Employees vaccinated

Employee headcount, 13 April 2013

Vaccination coverage (%)

Child and Adolescent Health Services

2,518

4,078

61.7

Goldfields

421

848

50.0

Great Southern

528

1,374

38.4

Kimberley

290

848

34.2

Midwest

759

1,313

57.8

North Metropolitan

4,862

11,915

40.8

Pilbara

672

812

82.8

South Metropolitan

7,821

14,870

52.6

South West

1,080

2,137

50.6

Wheatbelt

688

1,480

46.5

Missing data

145

-

-

Table 2 – Vaccination coverage by occupational group

Occupational Group

Employees vaccinated

Employee headcount, 13 April 2013

Vaccination coverage (%)

Nursing

7,484

17,125

43.7

Medical

2,223

5,107

43.5

Medical support

3,168

8,603

36.8

Administration and clerical

2,902

8,889

32.6

Hotel services

1,933

5,140

37.6

Site services

267

641

41.7

Other/data missing

1,807

-

-

Total

19,784

45,480

43.5

Coverage rates must be interpreted with caution because it is possible that not all staff members who were vaccinated had their vaccination recorded on a form that was sent to the Communicable Disease Control Directorate (CDCD) for data entry. Also, staff members who work in more than one health service can count in only one health service's vaccination rate. These factors may result in underestimation of vaccination uptake. In health services where staff turnover is high, vaccination uptake may be overestimated because the number of employees who should have been vaccinated during the influenza vaccination season is greater than the number of employees, based on employee headcount at the mid-point of the influenza vaccination season.

CDCD and WA health services are working together to refine data collection methods and improve staff influenza vaccine uptake in future years.

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Child influenza vaccination rate low despite rise in uptake

The uptake of influenza vaccination in children younger than 7 years of age in Western Australia rose between 2012 and 2013.

Influenza vaccination uptake in children younger than 7 years of age was 23% higher than for the corresponding period in 2012 (year-to-date ending September).

The number of influenza cases in children younger than 7 years of age was 50% lower than for the corresponding period in 2012 (year-to-date ending September).

Figure 1 – Influenza vaccination children <7 years, 2012 and 2013

Figure 2 – Influenza cases in children <7 years, 2012 and 2013

Annual vaccination offers the best protection against influenza, with free influenza vaccinations available for all children in WA from 6 months to under 5 years of age. Although influenza vaccine coverage in children increased between 2012 and 2013, the overall vaccine coverage for this age group remains low. WA total population estimates for 2013 show year-to-date influenza vaccination coverage of 9.42% in the under-7 age group.

Influenza vaccination is strongly recommended every year for anyone 6 months of age or older with a medical condition that places them at higher risk of severe illness from influenza. However, the majority of childhood influenza-related hospitalisations and deaths occur among children without underlying medical conditions. All children over 6 months of age should, therefore, be offered the annual influenza vaccine.

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New HIV and STI training for nurses

The Australasian Society for HIV Medicine (ASHM) is offering a face-to-face nurse training in Perth.

Primary healthcare nurses whose patients have, or are at risk of, blood-borne viruses (BBVs) and sexually transmissible infections (STIs) are encouraged to enrol in this training, which involves a combination of online and face-to-face education.

This training will enable participants to increase their scope of practice in HIV and sexual health. Aligned with the Sexual Health Nursing Competency Standards for Primary Health Care Nurses (2013), the course is designed to enhance participants' clinical skills, confidence and knowledge, enabling them to expand their role in caring for the sexual health of patients and the community. The course includes a session that focuses on helping participants advocate for an expanded role within their workplace and provides resources that can assist them in negotiating this process. The one-day course will be held at Grace Vaughan House on 9 March 2014.

To register or learn more about the courses visit the ASHM website (external site).

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Online service makes ordering brochures easy

Patient brochures produced by the Communicable Disease Control Directorate are now easy to access thanks to the new Department of Health online ordering service.

The brochures are provided free of charge and are available to all healthcare providers in Western Australia. Providers should register online and follow the prompts. Because the service is a State Government-funded initiative, brochures will not be posted to addresses outside of Western Australia.

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Guide clarifies HIV disclosure issues

The WA AIDS Council (WAAC), in partnership with the HIV/AIDS Legal Centre, recently launched a guide on disclosure of HIV status in Western Australia.

Current WA health laws do not specifically deal with sexual transmission of HIV, nor do they require a HIV-positive person to disclose his or her status to a sexual partner. A person who transmits HIV, however, may face criminal charges for transmission of the virus.

The guide is a simple-to-read handbook for HIV-positive people that will help them to understand when, or if, they have to disclose their HIV-status. It covers a variety of everyday situations including visits to dental, employment and insurance services.  It is a useful publication that should be made available to people newly diagnosed or living with HIV.

The booklet was based on the 2008 HIV/AIDS Legal Centre NSW disclosure guide. The WA Department of Health, People living with HIV and WAAC staff contributed to the WA guide. The WA Disclosure Guide can be ordered by contacting Liz Walker – HIV Positive Peer Education Officer at the WA AIDS Council on 9482 0000.

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Review of notifiable infectious diseases, Western Australia, 2012

Western Australia had 34,161 communicable disease notifications in 2012, a 12% increase on the number of notifications in 2011, and the highest number on record. This increase was due largely to an additional 3379 influenza notifications in 2012, and smaller increases in the number of Ross River virus, gonorrhoea, dengue fever, hepatitis B and rotavirus notifications.

The most frequently notified diseases in 2012 were genital chlamydia (11,878 cases), influenza (5,266), pertussis (3,388), varicella-zoster infection (2,497), gonorrhoea (2,128), campylobacteriosis (1,928), Ross River virus infection (1,377), and salmonellosis (1,177).

Enteric diseases

With the exception of rotavirus, the number of notifications for all enteric diseases declined or remained stable in 2012, compared to 2011.

The number of notifications for campylobacteriosis (n=1928) and cryptosporidiosis (n=168) in 2012 were 14% and 32% lower respectively, than the mean of the previous 4 years, while the number of salmonellosis notifications (n=1,177) was similar to the previous 4-year mean.

Rotavirus notifications rose 87% in 2012 (n=351) compared to 2011 although this was still lower than the previous 4-year mean (n=414). The majority of cases (61%) were in the 0–4 year age group, and of those 52% were fully vaccinated for this disease.

The number of shigellosis notifications in 2012 (n=53) was lower than in any of the previous 4 years, reflecting in particular a continuing decline in Shigella flexneri notifications among Aboriginal people in the Kimberley and Pilbara regions.

For all of the major enteric infections, with the exception of hepatitis A, notification rates were highest in the age group 0 to 4 years. The Kimberley region had the highest notification rates in the State for the more frequently notified enteric diseases. For most enteric infections, notification rates were also higher for Aboriginal people than non-Aboriginal people. The greatest difference was for shigellosis, for which the notification rate for Aboriginal people was 10 times that of non-Aboriginal people.

In 2012, hepatitis A notifications were 45% lower (n=14) than the historical 4-year mean, with notification numbers lower for both WA and overseas-acquired cases.

Of 8 cases of listeriosis notified in 2012, only 1 was related to pregnancy. The organism was isolated from the mother and the baby survived. The other cases involved middle-aged or elderly people, most of whom had one or more chronic medical condition that predisposed them to Listeria infection.

Typhoid (n=18) and paratyphoid (n=9) fever notifications were higher in 2012 than the previous 4-year means. All but 1 case acquired infection during overseas travel, mostly in Indonesia and India. The single apparent locally acquired infection was in an overseas-born person who was believed to be a chronic carrier, as S. Typhi was isolated repeatedly from their urine.

Vibrio parahaemolyticus notifications were also higher than the previous 4-year mean, due to an increase in overseas-acquired infections. The majority of cases (79%) were acquired overseas, mostly in South-East Asian countries—Thailand (4), Indonesia (3) and Malaysia (2).

One case of hepatitis E was notified in 2012, with infection acquired in Turkey.

Gastrointestinal disease outbreaks

There were 14 significant outbreaks of food-borne or suspected food-borne disease investigated in WA in 2012.

Of these, 4 were caused by Salmonella species, 1 each by Listeria and Campylobacter, 2 by norovirus, while for 6 outbreaks the infectious agent or toxin was not identified. The largest food-borne outbreak in 2012 was caused by Salmonella Typhimurium PFGE type 0039, with 128 cases notified. Most cases had consumed chicken prior to illness and chicken meat samples were positive for the same type of Salmonella.

Other Salmonella outbreaks were associated with eating salad from a takeaway outlet (4 cases), raw almonds produced in Australia (6 WA cases that were part of a multijurisdictional outbreak), and unknown food from a restaurant (4 cases). The Campylobacter outbreak, with 4 bacteriologically proven cases amongst a much larger number of ill patrons, was associated with eating chicken pate at a restaurant. The 2 norovirus outbreaks were thought to be due to food contaminated by ill food handlers. There was 1 identified case of Listeria infection in WA associated with a multijurisdictional outbreak of listeriosis caused by contaminated soft cheeses from a Victorian manufacturer.

There were 113 non-food-borne gastroenteritis outbreaks reported in WA in 2012, 45% higher than in the previous year. The causative agent for 68% (n=76) of these outbreaks was confirmed as norovirus, and rotavirus was the cause of 3 outbreaks. Non-food-borne outbreaks were predominantly associated with institutional settings, particularly residential care facilities (71%) and hospitals (20%).

Vaccine-preventable diseases

The pertussis epidemic that began in mid-2011 began to decline at the beginning of 2012 (Figure 1). In 2012, there were 3,388 pertussis notifications, 16% fewer than in 2011, but still twice the previous 4-year mean (n=1,684).

Figure 1 – Number of pertussis notifications in Western Australia by month, 2011 to 2012

Pertussis notification rates were highest in the 0–4 year age group (292 per 100,000 population), followed closely by the 10–14 and 5–9 year age groups (264 and 259 per 100,000, respectively). The decline in notifications from 2011 to 2012 was most evident in the 5–9 year and 10–14 year age groups (Figure 2). Notification rates were lowest in older teenagers and young adults, and increased again in middle-aged and older adults. Pertussis notification rates were highest in the Kimberley and Midwest regions, while the Goldfields and Wheatbelt regions had significantly lower rates than the rest of the State.

Figure 2 – Pertussis age-specific notification rates in Western Australia by year, 2011 and 2012

In 2012, there were 5,266 influenza virus notifications, similar to the number of notifications during the influenza pandemic of 2009. Influenza A/H3N2 and B subtypes comprised 48% and 37% of cases respectively, and only 0.5% of notified cases were attributed to A/H1N1(2009). Notification rates were highest in the Kimberley and Midwest regions and lowest in the Southwest region. The 2012 influenza season in WA commenced relatively early, with a sharp rise in activity that impacted significantly on health services—27% (n=1,420) of notified cases were hospitalised, the majority of whom were children aged 0-9 years (n=326, 23%) and older people aged 60 years and over (n=556, 39%). At least 33 deaths were associated with notified influenza in 2012.

There has been no endemic measles transmission in WA since the late 1990s, and the number of measles notifications remains low, associated mostly with importation from overseas and occasional limited local transmission. There were 6 measles cases in 2012; 4 of these were acquired overseas, in Thailand (n=3) and Pakistan (n=1), while the remaining 2 cases were acquired in WA from siblings who were infected overseas.

The median age of measles cases was 33 years (range: 8 to 40 years); 1 was a fully vaccinated child, 3 cases were partially vaccinated, 1 case was not vaccinated and 1 case had unknown vaccination status.

There were 2 cases of rubella notified in 2012, both were unvaccinated males aged 24 and 32 years. One case acquired his infection in Bali, Indonesia. The source for the other case was not determined, although he worked with fly-in-fly-out workers from overseas. There were no cases of congenital rubella in 2012 – the last reported case was acquired overseas in 2001.

Mumps activity remained stable and low in 2012, with 19 notifications, primarily adults living in the Perth metropolitan area. Nine cases acquired their infections in WA, 8 infections were acquired overseas, mostly in South-East Asian countries, 1 infection was acquired interstate and the place of acquisition for 1 case was unknown.

There was only 1 notification of invasive Haemophilus influenzae type b (Hib) infection in 2012, in a 2 year old fully vaccinated Aboriginal child.

There were 235 invasive pneumococcal disease (IPD) notifications in 2012, slightly fewer than the record high of 244 cases in 2011, when the new 13-valent conjugate vaccine was introduced. The number of cases aged 0–9 years decreased sharply from 72 in 2011 to 32 in 2012, while there were increases in the adult age groups, particularly those aged 30–39 years (75% increase) (Figure 3). The number of IPD cases in non-Aboriginal people rose by 24% between 2011 and 2012 (from 127 to 157 cases). However, the number of cases in Aboriginal people declined by 33% (from 111 to 78 cases), largely due to a dramatic decline in infections caused by serotype 1 pneumococci (from 44 to 15 cases) which had caused an outbreak in 2011, mostly among Aboriginal people from remote regions of WA.

In 2012, only 8% of IPD cases (n=14) were due to serotypes covered by the 7-valent conjugate pneumococcal vaccine, 41% (n=96) were caused by the additional 6 serotypes in the 13-valent vaccine, 27% were due to serotypes in the 23-valent vaccine (excluding the 13-valent vaccine serotypes) and 21% were caused by serotypes not covered by any vaccine.

Figure 3 – Invasive pneumococcal disease notifications by age group, Western Australia, 2011 and 2012

Varicella-zoster virus notifications for chickenpox declined in 2012 after increasing over the previous 4 years. In contrast, notifications for shingles and unspecified laboratory-confirmed varicella-zoster infections, increased for the fifth consecutive year. The majority of chickenpox cases in 2012 were among children aged 0-14 years (73%), while shingles and unspecified varicella-zoster infections were more evenly distributed across all age groups.

There was 1 tetanus notification in 2012 which involved an elderly woman who had no record of receiving tetanus vaccine and was reported to have had a thorn injury.

Vector-borne diseases

Notifications for both Ross River virus (n=1,377) and Barmah Forest virus (n=216) increased in 2012. Ross River virus activity increased in late 2011 and peaked in the first quarter of 2012, declining thereafter (Figure 4). Notification rates for Ross River virus infection were highest in the Great Southern and Kimberley regions.

By contrast, the number of Barmah Forest virus cases began increasing in the fourth quarter of 2012 and reached record levels during 2013. The unexpected increase in Barmah Forest virus cases has been attributed to an increase in false positive laboratory test results, which are currently under investigation.

Figure 4 – Number of notifications of Ross River virus and Barmah Forest virus infections in Western Australia by year and quarter, 2011 and 2012

No cases of Murray Valley encephalitis virus or Kunjin virus infection were notified in 2012.

The number of dengue fever notifications rose by 64% in 2012 to reach a record high of 532 cases. All cases were acquired overseas, the vast majority in Bali (80%) and Thailand (11%). The proportion of Bali-acquired infections has increased from 14% of notified dengue cases in the period 2001–2006 (a mean of 2 cases per year) to 35%, 44%, 65%, 82% and 85% of notified cases in 2007, 2008, 2009, 2010, and 2011 respectively. The estimated notification rate for dengue fever among WA air travellers to Bali increased from 3 to 100 cases per100,000 passengers between 2005 and 2012.

There were 4 chikungunya virus notifications in 2012, all acquired in Bali, Indonesia. There were 51 malaria notifications, the lowest number in 5 years, with infections all acquired overseas, mainly in African countries.

Schistosomiasis notifications have declined progressively from 337 cases in 2008 to 86 cases in 2012. In 2012, all infections were acquired overseas, primarily in African countries (97% of cases). The decline in notifications is attributed to a decrease in the number of immigrants and refugees arriving from endemic areas.

The number of rickettsial infections, including typhus, decreased in 2012 (n=33), but was 42% higher than the previous 4-year mean. Of the 33 cases, 18 (55%) were acquired overseas, mostly in Indonesia (n=13) and 11 were acquired in Western Australia, while for 4 cases, place of acquisition was unknown. Overseas-acquired rickettsial infections included murine typhus (56%), scrub typhus (22%) and spotted fever groups (22%). The 11 WA-acquired infections included 1 case with murine typhus, 4 with spotted fever group infections, and 6 cases with ambiguous serology.

Zoonotic diseases

Notifications for brucellosis, leptospirosis, psittacosis and Q fever continue to be infrequent. The single case of brucellosis reported in 2012 was acquired in Iraq. There were 4 reported cases of leptospirosis; 2 cases were locally-acquired, in an abattoir worker and a farmer, and 2 cases were associated with overseas travel, to Thailand and Laos, respectively.

There were 8 psittacosis notifications in 2012, of which 1 case was acquired overseas, in Bali. Of the 7 locally-acquired cases, most kept birds at home. There were 7 notifications of Q fever, the place of acquisition could not be determined for 1 case and 6 were locally-acquired infections—1 worked at an abattoir, 1 with cattle, 1 reported contact with feral goats, 3 cases did not have obvious livestock exposures and the exposure history for 1 case was not determined.

Blood-borne viral diseases

There were 24 “newly acquired” hepatitis B notifications in 2012, 29% lower than the previous 4-year mean of 34 notifications per year.

The number of “unspecified” hepatitis B notifications increased by 28% in 2012 (n=813) and was 19% higher than the previous 4-year mean. The increase was due largely to 234 (29%) notifications among illegal marine arrivals (IMAs) detained on Christmas Island or in the Curtin Detention Centre near Derby. Notifications for these centres are attributed to the Kimberley region, which as a consequence had the highest “unspecified” hepatitis B notification rate – 21 times the state rate. IMAs are screened for hepatitis B and other infections as part of arrival health checks, and usually originate from countries where hepatitis B is endemic.

In 2012, there were 124 “newly acquired” hepatitis C notifications, a 29% increase on the previous 4-year mean. The “newly acquired” hepatitis C notification rate for males was more than double that of females in 2012. “Unspecified” hepatitis C notifications increased marginally in 2012 (n=1028) compared to 2011 but were 4% lower than the previous 4-year mean (n=1073).

There were 2 notifications of hepatitis D in 2012.

Sexually transmissible infections

The number of genital chlamydia notifications plateaued in 2012 (n=11,878), although this was still 20% higher than the previous 4-year mean (n=9,886). As in previous years, a larger proportion of notifications were female (58%), although this was not consistent across age groups, with females more commonly notified than males in those aged under 25 years, whereas the converse was true in older individuals. The 20 to 24 year age group had the highest notification rate (2,396 notifications per 100,000 population). The chlamydia notification rate was 4 times higher in Aboriginal people compared to non-Aboriginal people. Reflecting this differential, notification rates were highest in the Kimberley, followed by the Goldfields, Pilbara and Midwest regions.

Gonorrhoea notifications increased in 2012 for the third consecutive year, to 2,128 cases, the highest number on record, and 36% higher than the previous 4-year average (n=1,571). Notifications for non-Aboriginal people increased by 45% between 2011 (n=659) and 2012 (n=957), accounting for most of the overall increase. The number of gonorrhoea notifications for Aboriginal people was stable in 2012, although the notification rate remained markedly higher (29 times) compared to non-Aboriginal people (1,132 versus 40 cases per 100,000 population). The majority of non-Aboriginal cases were male (71%) while the Aboriginal cases were fairly evenly spread across the sexes (47% male). The North Metropolitan region had the largest increase in the number of cases in 2012, followed by the Kimberley and South Metropolitan regions (see Figure 5). The Kimberley region had by far the highest notification rate in 2012 (1,778 cases per 100,000 population). In terms of age, notification rates were highest in the 15 to 24 year age group (352 per 100,000 population).

Figure 5 – Number of gonorrhoea notifications in Western Australia by region, 2011 and 2012

Infectious syphilis notifications decreased by 34% from 2011 (n=121) to 2012 (n=80). Both Aboriginal and non-Aboriginal cases declined in 2012, the former by 50% (from 26 to 13 cases) and the latter by 29% (from 95 to 68 cases). The notification rate for Aboriginal people in 2012 was 5.8 times the rate for non-Aboriginal people (16.9 versus 2.9 cases per 100,000 population). For non-Aboriginal people the majority of notifications were in males (97%), whereas among Aboriginal people notifications were spread evenly by gender (54% male). The highest notification rates were for the 25 to 34 years and 35 to 44 year age groups (both 6.3 per 100,000 population). Notification rates were highest in the Kimberley and Goldfields regions. The number of non-infectious syphilis notifications in 2012 (n=137) was 42% higher than the previous 4-year mean (n=96). There were no cases of congenital syphilis notified in 2012.

No cases of chancroid were reported in 2012, and there was 1 locally-acquired case of donovanosis in a non-Aboriginal person with a partner from overseas.

Annual notifications of human immunodeficiency virus (HIV) infection reached a record peak of 121 cases in 2012, increasing from 105 cases in 2011. There were 94 (78%) male cases (median age 39 years) and 27 (22%) female cases (median age 33 years), and most cases resided in the Perth metropolitan area (85%). The distribution of exposure groups was similar to previous years with the majority of cases (97%) reporting sexual contact as the most likely route of transmission. Of the male cases, over half (58%) reported sex with men, 38% reported heterosexual exposures and 2% (2 cases) reported injecting drug use as their only risk factor. Most female cases reported heterosexual contact (96%) and 4% other or unknown exposures.

Of the heterosexually acquired male and female HIV cases, 46% and 67%, respectively, were born overseas and also acquired their infection overseas, generally in the region of their birth. Australian-born males who acquired HIV overseas made up 38% of heterosexually acquired male cases, with most of these men acquiring their infection in South-East Asia. The number of people reporting transmission via injecting drug use remained low (2 cases). No new cases of HIV infection were reported among Aboriginal people in 2012.

Other diseases

There were 62 acute rheumatic fever notifications in 2012, almost triple the number in 2011. All cases were Aboriginal people, and all but 5 lived in remote areas of the state. The age range for cases was 3 to 44 years (median age 10 years). It is unclear to what extent the increase reflects a true increase in disease incidence, versus improved case ascertainment and/or notification.

The number of invasive meningococcal disease notifications in 2012 (n=19) was 21% lower than the previous 4-year mean (n=24), and the lowest number recorded in over 20 years. The majority of infections were due to serogroup B organisms (15 cases), 2 were serogroup C, 1 was serogroup Y and 1 was untyped. The largest proportion of cases was in the 0 to 4 year age group (26%), followed by the 20 to 24 year age group (21%). There were 3 deaths in 2012—2 cases aged 1 and 23 years had serogroup B infections, while the third, who was 94 years old, had serogroup C disease.

There were no notifications for haemolytic uraemic syndrome in 2012 and 3 notifications for Creutzfeldt-Jakob disease.

Legionellosis notifications increased for the third consecutive year in 2012 (n=87) and were 36% above the previous 4-year mean (n=64). The majority of infections were due to Legionella longbeachae (85%), which is associated with exposure to gardening soils and potting mixes, and the remainder were caused by L. pneumophila, associated with spray mists from warm water sources such as air conditioning cooling towers, spas, fountains and hot water systems. Of the 13 L. pneumophila cases notified in 2012, 4 were acquired overseas; 3 in Bali, Indonesia and 1 in Thailand. The 3 Bali-acquired cases were notified a month or more apart and stayed at different hotels. One of these cases stayed at the same hotel in Kuta, Bali that was associated with an outbreak in Australian travellers that started in 2010 and extended into 2011.

Tuberculosis (TB) notifications have increased each year from 2008 (n=95) to 2012 (n=172), due to increasing numbers of overseas-born cases, from 88 in 2008 to 158 in 2012. Of the 14 Australian-born cases in 2012, 4 acquired their infection in WA. Three cases notified in 2012 had multi-drug resistant TB and 3 of the cases were relapses.

Three cases of meliodosis with an age range of 62 to 85 years were notified in 2012. All were acquired in Western Australia, 2 in the Kimberley region and 1 seemingly in the outer Perth metropolitan area. No cases of leprosy were notified in 2012.

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