Vector-borne. Diseases. Chapter overview. Chapter

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1 Chapter 7 Aedes aegypti Vector-borne Diseases Chapter overview Many mosquito-borne diseases were under surveillance in Queensland during the period Of these, Ross River virus (RRV) infection, Barmah Forest virus (BFV) infection, dengue and malaria were the most commonly reported. While the morbidity associated with these diseases is significant, among the 15,44 notifications of all mosquito-borne disease over the five year period, only one death (from dengue) was recorded. Queensland is the only Australian state or territory where locally transmitted dengue currently occurs, as the vectors Aedes aegypti and Aedes albopictus are limited to this state. There is however national interest in the spread of these vectors. Ae. aegypti and dengue have previously been more widespread in Australia and incursion into other jurisdictions could occur. Ae. albopictus, currently restricted to islands in the Torres Strait, is tolerant of cooler climates and could potentially spread as far south as Melbourne. Unlike alphaviruses such as RRV and BFV, humans are the sole reservoir of dengue and malaria. Active public health intervention, with targeted vector control and public education, is required to prevent ongoing transmission. Noteworthy observations of the epidemiology of mosquito-borne diseases in Queensland during the period include: Queensland s notification rates of mosquito-borne disease were two to three times higher than national rates. Notification rates of all mosquito-borne diseases were highest in the Northern Area Health Service (NAHS), and the health service districts (HSDs) of Torres Strait and Northern Peninsula Area (Torres/NPA) and Cape York in particular. Notification rates of Barmah Forest virus infection increased over the five year period, most notably in the NAHS. Several large outbreaks of locally acquired dengue occurred. Most cases of malaria were imported, with only 13 locally acquired cases, including an outbreak in 22 in North Queensland involving 1 people. Notification rates of malaria were lower compared to the period. Notifiable Diseases Report

2 Figure 7.1 Notifications of mosquito-borne diseases, Queensland, Notifications RRV BFV Dengue Malaria Other Dengue Overview Dengue is characterised by an acute febrile illness with symptoms of headache, muscle and joint pains, gastrointestinal symptoms and often a rash. It is caused by the dengue virus, of which there are four different serotypes. Haemorrhagic and shock syndromes, which can result in death, occur rarely but are more common when an individual experiences subsequent infection with a different serotype. While imported cases of dengue are reported throughout Australia, outbreaks of locally acquired dengue have been confined to north Queensland during the last decade. Outbreaks can occur when an infected visitor or resident arrives or returns from an endemic area overseas, to an area in Queensland where competent vectors are present. The main vector, Aedes aegypti, is present as far south as Goomeri on the coast and Charleville inland. Another potential vector, Aedes albopictus, is currently present only in the Torres Strait. 1 Preventing establishment of Ae. albopictus on the mainland is a high priority as it is capable of surviving and transmitting dengue in temperate climates as far south as Melbourne. With dengue incidence on the rise globally, 2 the control of dengue and dengue vectors is of vital importance for both Queensland s and Australia s health security. Summary of notifications Notifications were classified as locally acquired, overseas-acquired or of unknown acquisition source. Locally acquired notifications were those with an outbreak identifier and where the source of infection was either missing or coded as Australia. Notifications without an outbreak identifier, but with Australia as the source of infection, were also classified as locally acquired notifications. Notifications with a valid non-australian source of infection were classified as overseas-acquired. There were a total of 1,275 notifications of dengue from 22 to 26. Of these, 48 were of unknown acquisition source (4%), and were excluded from the rest of the analysis. Of the remaining 1,227 cases, 1,3 were locally acquired (84%) and 197 were acquired overseas (16%). 168 Notifiable Diseases Report Background image: Aedes aegypti

3 Aedes aegypti Between 1997 and 26, the number of dengue notifications (all sources) in Queensland ranged from 44 in 21 to 725 in 23. Notification rates in Queensland ranged from 1.2 to 19.1 per 1,, compared to a range of.6 to 4.3 per 1, for Australia (data not shown). Australian rates are heavily impacted upon by outbreaks of dengue in Queensland. Large outbreaks of dengue occurred in north Queensland in 1998, 23 and 24. In 1998, the large number of cases with unknown acquisition source (Figure 7.2) were most likely locally acquired cases. Figure 7.2 Notifications Dengue notifications by acquisition source, with dengue notification rate per 1, population, Queensland, Notification rate Year Locally acquired cases Overseas acquired cases Cases unknown source Queensland rate Overseas-acquired dengue and locally acquired dengue have different public health implications. People with overseas-acquired dengue only pose a public health risk if they visit areas where a dengue vector exists, while locally acquired dengue always requires active public health intervention. Data on locally acquired dengue notifications can facilitate the targeting of preventive efforts and monitoring of effectiveness of prevention and control activities. For these reasons, the epidemiology of dengue is presented separately here by source of acquisition. Dengue overseas-acquired Between 22 and 26, an average of 39 cases per year of overseas-acquired dengue were notified in returned travellers/visitors (range 32 to 49). Three of these returned travellers were subsequently linked to north Queensland outbreaks, while the remaining cases were not known to be associated with further cases in Queensland. For 78 people (4%), dengue virus serotype was ascertained: 28 were serotype 2, 24 serotype 1, 16 serotype 3 and 1 were serotype 4. The mean and median age of returned travellers/visitors notified with overseas-acquired dengue was 39 and 37 respectively, with a range of one to 82 years. Fifty-seven percent of cases were male. The number of overseas-acquired dengue notifications by HSD for the period are shown in Table 7.1. There were 83 notifications in Central Area Health Service (CAHS) residents, 65 in Southern Area Health Service (SAHS) residents, and 39 in NAHS residents, with ten cases unable to be assigned to a Queensland HSD. Notifiable Diseases Report

4 The highest rate of overseas-acquired dengue was in the Torres/NPA HSD (5.8 per 1, population). This may be due to frequency of travel to dengue-endemic neighbouring countries such as Papua New Guinea and Indonesia and/or greater awareness of dengue. Table 7.1 Notifications of overseas-acquired dengue and average annual notification rates by health service district, Queensland, Resident Health Service District Notifications Notification rate (per 1, population) Resident Health Service District Notifications Notification rate (per 1, population) Banana. Logan-Beaudesert 8.5 Bayside 5.5 Mackay 4.7 Bowen. Moranbah. Brisbane North Mt Isa. Brisbane South North Burnett. Bundaberg. Northern Downs. Cairns Redcliffe- Caboolture 8.9 Cape York. Rockhampton. Central Highlands. Roma. Central West South Burnett. Charleville. Southern Downs. Charters Towers Sunshine Coast Fraser Coast. Tablelands Gladstone 1.5 Toowoomba. Gold Coast Torres Gympie. Townsville Innisfail 1.6 West Moreton 2.2 Notifications of overseas-acquired dengue showed no marked seasonality, although they were most common in ch. Forty of the 197 notifications (2%) recorded from 22 to 26 had onset dates in ch. There were also 28 notifications in both January and il, which is higher than the 16 expected if notifications were evenly distributed. Travel to South-East Asian and Pacific Island countries was usually reported, with only seven of 197 notifications (4%) acquired from outside those geographic areas. The following countries were the most commonly recorded sources of infection: Indonesia (37 cases), Papua New Guinea (21 cases), the Philippines (18 cases), and Thailand (17 cases). 17 Notifiable Diseases Report Background image: Aedes aegypti

5 Aedes aegypti Dengue locally acquired Statistics at a glance (22 26 Dengue fever locally acquired) Average number of notifications per year 26 Queensland rate compared to Australian rate Is any trend in rate of disease apparent (22 26)? Predominant age group Not applicable Not applicable 2 49 years Percent of all notifications in predominant age group 62% Percent male 52% Differences between area health service rates Health service districts with highest rates 99% of notifications are for NAHS residents Torres/NPA^ Percent with information on Indigenous status 86% Indigenous people as a percent of all notifications 28% ^ Torres Strait and Northern Peninsula Area. Summary of notifications Over the period, notifications of locally acquired dengue varied between 25 and 667 per year. Large outbreaks occurred in 23 and 24 (Figure 7.3). Figure 7.3 Notifications of locally acquired dengue, Queensland, Notifications Year Over the period, 54% of locally acquired dengue cases were in residents of Cairns HSD (552 cases), 31% were in Torres/NPA HSD residents (321 cases), and 1% were in Townsville HSD residents (15 cases)(table 7.2). Torres/NPA HSD had the highest notification rate at per 1,, followed by Cairns at 15.4 per 1,. Notifiable Diseases Report

6 Table 7.2 Notifications of locally acquired dengue and average annual notification rates per 1, population for Northern Area Health Service districts, Queensland, 22 26^ Northern AHS HSDs Total notifications Average annual notification rate Average annual population at risk Bowen ,22 Cairns ,85 Cape York ,453 Charters Towers. 15,484 Innisfail ,789 Mackay ,372 Moranbah. 19,69 Mt Isa. 3,679 Tablelands ,87 Torres ,388 Townsville ,724 Total, NAHS ,329 ^ 25 HSD denominator data were used for 26, as 26 denominator data were not available at time of analysis. Ten cases of locally acquired dengue during the period did not have information which allowed HSD assignment. Age and sex Over the period, average annual age-specific notification rates of locally acquired dengue in NAHS were highest in age groups between 2 and 29 years of age (over 55 per 1,) (Figure 7.4). The mean and median ages of notified cases were 36 and 34 years respectively (range under one year to 87 years). A total of 14 children aged less than five years and 23 children five to nine years of age were notified with dengue over the period. Children usually have milder disease and so may be less likely to be tested. Slightly more notifications were in males than females, with a male-to-female ratio of 1.1:1 Figure Notifications of locally acquired dengue by age group and sex, and average annual age-specific rates per 1, NAHS population, Queensland, Notifications Rate per 1, Age group (years) Female Male Age-specific rate 172 Notifiable Diseases Report Background image: Aedes aegypti

7 Aedes aegypti Dengue serotypes Of the 1,3 locally acquired cases of dengue from 22 26, 721 (7%) had dengue serotype ascertained. Of these, 91% were serotype 2 (654 cases) and 8% were serotype 4 (56 cases). Serotypes 3 and 1 accounted for six and five cases respectively. Seasonality Over the period, notified cases of locally acquired dengue peaked in ch (22, 23 and 25), ruary (24), or (26) (Figure 7.5). Ninety-three percent of cases occurred between November and, and 62% in the months of ruary, ch and il. Figure 7.5 Notifications of locally acquired dengue by year and month of onset, Queensland, Notifications Jan Oct Nov Dec Jan Aug Aug Sep Dec Jan Year and month of onset Indigenous status From 22 to 26, Indigenous status for locally acquired dengue notifications was well-recorded, with only 14% missing this information. Of all notifications of locally acquired dengue, 285 were in Indigenous people (28%). The Indigenous dengue notification rate was 8.8 times higher than the rate in people of non-indigenous/unknown status (35.1 compared to 4. per 1,). The number of notifications of locally acquired dengue in Indigenous people ranged from two in 26 to 152 in 23. Fifty-two percent of notifications were in females with a male-to-female ratio of.9:1.. Most notifications were in residents of Torres/NPA HSD (241, 85%). Other HSDs with Indigenous notifications were Cairns (32 notifications), Tablelands (six notifications), and Townsville (two notifications). Sixteen of the 37 notifications (43%) of locally acquired dengue in children aged less than 1 years were in Indigenous children. Indigenous cases were generally younger compared to cases overall, with a mean and median age of 31 and 29 years respectively (range under one year to 85 years). One death from dengue was recorded during the five year period 22 26; this was a 4 year old Indigenous person from the Torres Strait infected with dengue serotype 2. The higher notification rate of locally acquired dengue in Indigenous people is largely due to the particularly high rate in the Torres Strait. As noted above, the Torres HSD also has the highest rate of overseas-acquired dengue, possibly due to frequency of travel to dengue-endemic neighbouring countries such as Papua New Guinea and Indonesia. Eighty-three percent of the Torres Strait population is Indigenous compared to only 1% of the population of other north Queensland regions (Cairns, Cape York, Mt Isa, and Townsville). 3 Notifiable Diseases Report

8 Dengue outbreaks Between 22 and 26 there were thirteen outbreaks of dengue involving local transmission. Notifications per outbreak ranged from one to 536, with a median number of eight notifications per outbreak. A total of 1,38 people were notified in relation to these outbreaks, including three people who acquired their disease overseas and acted as the index case, and five residents of other states and territories. An outbreak is considered over when no new cases are reported for 9 days following the onset date of the last case. Outbreaks lasted from one day to 126 days, with a median of 1 days. The most recent outbreak in 26 lasted 126 days with 29 cases notified. All dengue virus serotypes (1, 2, 3 and 4) were responsible for at least one outbreak, although serotype 2 dengue was the most common, causing six of the 13 outbreaks. The overseas place of acquisition for the index case was not reported in all but three of the outbreaks. For the three index cases where source of acquisition was identified, two individuals acquired the disease at sea and one in Papua New Guinea. Outbreaks were limited to areas within NAHS: Cairns, Townsville, Torres/NPA and Tablelands HSDs. Table 7.3 Characteristics of dengue outbreaks in Queensland, Year(s) Location (s) Total cases Duration (days) Dengue serotype 26 Cairns Townsville Townsville Torres Torres Cairns/Townsville/Torres Torres & Cairns Cairns eeba Cairns Kuranda Townsville Cairns Source: Public health implications The control of dengue outbreaks and the dengue mosquito vectors are of special importance to Australia. Within Queensland Health s NAHS, the Tropical Public Health Unit (TPHU) Dengue Action Response Team (DART) is tasked with leading dengue outbreak control responses, as documented in the TPHU Dengue Fever Management Plan. 4 In neighbouring countries such as Indonesia, large outbreaks of dengue occur; between January and il 24, Indonesia reported 58,31 cases of dengue and dengue haemorrhagic fever, including 658 deaths Notifiable Diseases Report Background image: Aedes aegypti

9 Aedes aegypti Ross River virus infection Statistics at a glance (26 Ross River Virus) Number of notifications in 26 2,615 Queensland rate compared to Australian rate Is any trend in rate of disease apparent (22 26)? Predominant age group 2.4 times higher No trend years Percent of all notifications in predominant age group 75% Percent male 47% Differences between area health service rates Health service district(s) with highest rates NAHS 1.8 times higher than CAHS and 2.3 times higher than SAHS Cape York Percent with information on Indigenous status 13% Indigenous people as a percent of all notifications 2% Epidemiology: key points Queensland s notification rates are consistently two to three times higher than Australian rates. NAHS has the highest notification rates of RRV infection, although rates over the period were generally lower than for the period. Introduction Ross River virus (RRV) infection, characteristically a self-limiting febrile illness with arthralgia/ arthritis, is the most common and widespread mosquito-borne disease in Australia. Tiredness is often a prominent symptom of illness and prolonged symptoms, in some cases for up to a year, may occur. The illness is similar to that caused by Barmah Forest virus. Summary of notifications Over the period, annual notifications of RRV infection ranged from 886 in 22 to 2,615 in 26, with a total of 9,27 notifications. The notification rate varied from 24 per 1, in 22 to 66 per 1, in 23. Notification rates from 1997 to 26 were generally highest in the NAHS (Figure 7.6). The notification rate in NAHS in 26 (112 per 1,) was nearly double the Queensland rate, and the highest in NAHS since 2. However, NAHS rates over the period were generally lower than for the period. In CAHS there were an unusually large number of notifications (1,416) in 23. Between 22 and 26, Queensland annual notification rates of RRV infection were 2.4 to 3.4 times higher than the Australian rates. In 26, notifications were widely distributed geographically, with all HSDs reporting cases (Figure 7.9). The highest numbers of notifications were in Brisbane North HSD (359), Townsville HSD (272) and Logan-Beaudesert HSD (176). The highest notification rates were in Cape York HSD (241 per 1,), followed by Northern Downs, Townsville and Southern Downs HSDs, with rates between Notifiable Diseases Report

10 193 and 132 per 1, population. Other HSDs with rates greater than 1 per 1, in 26 were Innisfail, Bowen, Central West, Gympie, Mackay, Moranbah, Mt Isa, Torres/NPA and North Burnett. The Sunshine Coast HSD recorded the highest number of notifications for a HSD in a single year in 23, with 54 notifications. Figure 7.6 Notification rates of Ross River virus infection: Queensland, Queensland area health services, and Australia, Rate per 1, Year Queensland QLD-NAHS QLD-CAHS QLD-SAHS Australia Age and sex The age distribution of notifications in 26 followed a normal distribution pattern (Figure 7.7), with a mean and median age of 43 years and 42 years respectively (range one year to 9 years). Rates were highest in age groups from 35 to 54 years of age, with age-specific notification rates between 15 and 117 per 1,. Only 15 (less than 1%) notifications were in children aged less than 1 years. Slightly more notified cases were female, with a male-to-female ratio of.9:1. Figure 7.7 Notifications of Ross River virus infection by age group and sex, and age-specific notification rates, Queensland, 26 Notifications Age group (years) Rate per 1, Female Male Age-specific rate 176 Notifiable Diseases Report Background image: Aedes aegypti

11 Aedes aegypti Seasonality A clear seasonal pattern of notifications is observed throughout Queensland (Figure 7.8), although the height of the peak varies by year and AHS. Over the five year period 22 26, 88% of notified cases occurred during the six months between January and e. ch and il were the months with the highest numbers of notified cases. In 26, 49% of notified cases occurred in ruary/ch. Figure 7.8 Notifications of Ross River virus infection by month of onset and Queensland area health service, Jan Aug Sep Oct Nov Dec Jan Aug Sep Oct Nov Dec Jan Aug Sep Oct Nov Dec Jan Aug Sep Oct Nov Dec Jan Aug Sep Oct Nov Dec Year and month of onset Central AHS Northern AHS Southern AHS Indigenous status Over the five years to 26, 143 notified cases were recorded as Indigenous, including 41 in 26. Indigenous status was not recorded for 89% of notifications between 22 and 26, with no apparent improvement in data completeness over this period. Due to this high proportion of missing data, rates were not computed and comparisons are not reported. Public health implications Reducing the burden of Ross River virus infection requires a combination of prevention and control measures by public health authorities, local councils, and individuals to reduce mosquito numbers and avoid bite exposures. Several authors have raised the possibility that predictive models which incorporate climatic data including rainfall, 6-8 relative humidity, 8 average sea temperature 6 and/or tide height 6,7 can provide early warnings in relation to epidemics, in time to inform a public health response. Rainfall appears to be the single most important factor, with above-average rainfalls occurring nationally in the months preceding outbreaks. 7 In Cairns, increased disease notifications followed two months after above-average rainfall. 8 However, climate appears to influence arboviral activity differently in tropical, arid and temperate regions. 7 Notifiable Diseases Report

12 Figure 7.9 Average annual notification rates of Ross River virus infection by Queensland health service district, Notification rate, 22 to 26 per 1, population 2+ Banana 1 to Bundaberg 7 to to 69.9 to 35.9 Torres North Burnett Fraser Coast Gympie Cape York Cairns Northern Downs Southern Downs South Burnett Toowoomba West Moreton Sunshine Coast Redcliffe- Caboolture Logan/ Beaudesert Brisbane North Bayside Brisbane South Gold Coast Inset Tablelands Innisfail Townsville Mt Isa Charters Towers Bowen Mackay Moranbah Rockhampton Central West Central Highlands Gladstone Charleville Roma See inset 178 Notifiable Diseases Report Background image: Aedes aegypti

13 Aedes aegypti Barmah Forest virus infection Statistics at a glance (26 Barmah Forest Virus) Number of notifications in Queensland rate compared to Australian rate Is any trend in rate of disease apparent (22 26)? Predominant age group 2.3 times higher Increasing 3 59 years Percent of all notifications in predominant age group 61% Percent male 5% Differences between area health service rates Health service districts with highest rates NAHS 2.5 times higher than CAHS and 6.3 times higher than SAHS Cape York Percent with information on Indigenous status 26% Indigenous people as a percent of all notifications 4% Epidemiology: key points Notification rates of BFV infection doubled in both Queensland and Australia between 22 and 26. Queensland notification rates were two to three times Australian rates. Within Queensland, notification rates were highest for NAHS in most years from 1997 to 26, with the NAHS rate almost tripling between 22 and 26. Increased notification rates may be due in part to greater awareness and testing. Introduction Barmah Forest virus (BFV) infection is a mosquito-borne disease with symptoms similar to that of Ross River virus infection. BFV is found only in Australia. Notifiable Diseases Report

14 Summary of notifications Over the period, the annual number of notifications of Barmah Forest virus infection varied from 387 in 22, to 957 in 26, with a total of 3,48 notifications over the five year period. The year 23 was an epidemic year in both CAHS and SAHS, with notification rates two to three times greater compared to the period (Figure 7.1). In NAHS, the 23 notification rate was similar to that of the previous two years, but a sharp increase was seen over the following three years. In 26, the notification rate in NAHS (61 per 1,) was 2.7 times the rate in 22 (23 per 1,). In 26, NAHS reported 398 notifications of BFV infection, accounting for 42% of Queensland notifications that year. Of all Queensland HSDs, Sunshine Coast HSD reported the most notifications, with 525 notifications between 22 and 26. Cape York had the highest notification rate (187 per 1, population) (Figure 7.1). In Cape York HSD, notifications increased from four in 22 to 28 in 26. Notifications in Townsville HSD and Mt Isa HSD more than quadrupled between 22 and 26, from 28 to 119 for Townsville, and from five to 22 for Mt Isa. Cairns HSD notifications increased from 27 to 71. Outside the NAHS, notifications in the Sunshine Coast HSD also increased from 61 in 22 to 112 in 26, with 27 notifications in 23 (24% of all notifications that year). Figure 7.1 Notification rates of Barmah Forest virus infection: Queensland, Queensland area health services, and Australia, Rate per 1, Year Queensland QLD-NAHS QLD-CAHS QLD-SAHS Australia 18 Notifiable Diseases Report Background image: Aedes aegypti

15 Aedes aegypti Age and sex In 26, the highest age-specific notification rates of Barmah Forest virus infection were in age groups between 4 and 59 years of age (Figure 7.11). While the overall sex ratio was 1:1, a larger proportion of cases aged 1 29 years were female, and a larger proportion of those aged 55 years and older were male. Mean and median ages overall were 42 and 43 years respectively, with a range of two to 9 years. There were three notifications in children aged less than five years, and nine in children aged five to nine years. Figure 7.11 Notifications of Barmah Forest virus infection by age group and sex, and age-specific notification rates, Queensland, Notifications Rate per 1, Age group (years) Female Male Rate Notifiable Diseases Report

16 Jan Aug Sep Oct Nov Dec Jan Aug Sep Oct Nov Dec Jan Aug Sep Oct Nov Dec Jan Aug Sep Oct Nov Dec Jan Aug Sep Oct Nov Dec Seasonality A seasonal pattern was apparent from 22 to 26, with the highest numbers of notifications occurring in ch, il and (Figure 7.12). Forty-three percent of notifications over the five year period occurred during these three months. Of note is the unusually high number of notifications from CAHS in il and of 23 (164 and 13 notifications respectively, including 6 and 49 notifications from Sunshine Coast HSD). Figure 7.12 Notifications of Barmah Forest virus infection by month of onset and Queensland area health service, Notifications Year and month of onset Central AHS Northern AHS Southern AHS Indigenous Status Over the five years to 26, between eight and 42 notified cases per year were recorded as Indigenous, including 41 in 26. The number of Indigenous notifications increased over the five year period. Data completeness for this variable was poor, with only 26% of notifications in 26 having information on Indigenous status. Completeness did however improve over the five years, increasing from only 1% of notifications with complete data in 22. With 42 notifications in 26, the notification rate of BFV infection in Indigenous people (23 per 1,), was the same as that in people of non-indigenous/unspecified status. Caution should however be used when comparing these rates, given the high proportion of missing data. Public health implications The increase in notification rates of BFV infection seen in Queensland and Australia may be due in part to greater awareness and testing. Other possible contributing factors could include increased opportunities for human-mosquito interaction (eg. urban development near breeding sites), or changes in vector and animal reservoir ecologies. Reducing the burden of Barmah Forest virus infection requires a combination of prevention and control measures by public health authorities, local councils, and individuals to reduce mosquito numbers and avoid bite exposures. 182 Notifiable Diseases Report Background image: Aedes aegypti

17 Aedes aegypti Figure 7.13 Average annual notification rates of Barmah Forest virus infection by Queensland health service district, Notification rate, 22 to 26 per 1, population 7+ Banana 5 to 69.9 Bundaberg 3 to to 29.9 to 9.9 Torres North Burnett Fraser Coast Gympie Cape York Cairns Northern Downs Southern Downs South Burnett Toowoomba West Moreton Sunshine Coast Redcliffe- Caboolture Logan/ Beaudesert Brisbane North Bayside Brisbane South Gold Coast Inset Tablelands Innisfail Townsville Mt Isa Charters Towers Bowen Mackay Moranbah Rockhampton Central West Central Highlands Gladstone Charleville Roma See inset Notifiable Diseases Report

18 Malaria Statistics at a glance (26 Malaria) Number of notifications in Queensland rate compared to Australian rate Is any trend in rate of disease apparent (22 26)? Predominant age group 1.7 times higher No trend 2 59 years Percent of all notifications in predominant age group 68% Percent male 67% Differences between area health service rates Health service district(s) with highest rates NAHS 2 times higher than CAHS or SAHS Torres/NPA^ Percent with information on Indigenous status 67% Indigenous people as a percent of all notifications 2% ^ Torres Strait & Northern Peninsula Area; Note: nearly all notifications are acquired outside Queensland. Epidemiology: key points Of the 1,269 malaria notifications from 22 to 26, only 13 were locally acquired cases. Queensland consistently had higher rates of malaria compared to national rates; this could be due to increased testing and awareness, and/or the proximity to endemic areas such as PNG. The number of notifications for males was double that for females. From 22 to 26, a shift in the proportions of infecting species occurred, with decreasing notifications of Plasmodium vivax and increasing notifications of P. falciparum. Between 1997 and 26 notification rates decreased, particularly in the NAHS. 184 Notifiable Diseases Report Background image: Aedes aegypti

19 Aedes aegypti Introduction Malaria is a potentially serious acute febrile illness caused by Plasmodium species, which are protozoal parasites spread by Anopheles mosquitoes. Malaria causes a million deaths annually worldwide. 9 Queensland is the only state or territory in Australia that has reported locally acquired malaria over the decade to A point source outbreak of malaria transmitted by local An. farauti mosquitoes occurred in 22. This outbreak originated from a recently returned traveller, likely to have been infected in Indonesia, who camped in the Daintree National Park. Ultimately, nine additional people were infected. 11 Prior to this, only sporadic cases of locally acquired malaria had been reported in the Torres Strait and north Queensland in 1997 and Four other cases of locally acquired malaria were reported between 22 and 26, all on Saibai Island in the Torres Strait: one in 22 and a cluster of three cases in 24. Summary of notifications Between 22 and 26 a total of 1,269 cases of malaria were notified in Queensland, with an average of 254 cases annually. Only 13 cases were reported to be locally acquired. A trend towards higher numbers of cases caused by P. falciparum, and fewer caused by P. vivax was observed (Table 7.4). Between 22 and 26, the proportion of annual notifications of malaria caused by P. falciparum increased from 25% to 47%, while infections caused by P. vivax decreased from 7% to 48% of all malaria notifications. Table 7.4 Malaria notifications by infecting species, Queensland, Year of onset Infecting species Notifications Species % Plasmodium falciparum Plasmodium vivax Plasmodium malariae Plasmodium ovale Plasmodium, unspecified Total Notifiable Diseases Report

20 Notification rates of malaria in Queensland were generally lower over the period compared to the period, particularly in the NAHS (Figure 7.14). Queensland rates have consistently been around twice the national rates. This may be due to increased awareness, testing and screening for the disease, and/or geographic proximity of north Queensland, and particularly the Torres Strait, to endemic areas. Figure 7.14 Malaria notification rates: Queensland, Queensland area health services, and Australia, Rate per 1, Year Queensland QLD-NAHS QLD-CAHS QLD-SAHS Australia From 22 to 26, the HSDs with the highest malaria notification rates were Torres, Cairns, Tablelands and Townsville, with average annual rates of 168, 14, 13 and 1 per 1, residents respectively. Age and sex Age-specific rates showed no particular pattern, with slightly higher rates in age groups between 2 and 39 years (Figure 7.15). Malaria notification rates decreased after age 6, which could reflect lower likelihood of exposure. Twenty-two percent of malaria notifications in 26 were in children aged less than 15 years, including one in an infant aged less than one year, 2 aged one to four years, 19 aged five to nine years and 17 aged 1 14 years. More notifications were in males than females across all age groups except for year olds (Figure 7.15), with an overall male-to-female ratio of 2: Notifiable Diseases Report Background image: Aedes aegypti

21 Aedes aegypti Figure 7.15 Malaria notifications by age group and sex, and age-specific notification rates, Queensland, 26 * Notifications Rate per 1, Age group (years) Female Male Age-specific rate * In 26, there were no cases notified for 65 to 74 year olds. Indigenous status Over the period, 65 cases of malaria (5% of total notifications) were recorded as being Indigenous. Of note, although the notification rate of malaria was highest in the Torres/NPA HSD in 26, six of the ten notified cases were in non-indigenous people. While the overall notification rate of malaria was no higher in Indigenous people compared to people of non-indigenous/unknown status, caution is required in comparing rates due to the high proportion of missing data on Indigenous status (33% missing in 26). Country of acquisition In 26, the country of acquisition was recorded for 77% of malaria notifications. The most common country of acquisition recorded was Papua New Guinea with 132 cases (66% of cases with valid country of acquisition data). Acquisition from other Pacific Island and South-East Asian countries was reported for 23 cases (11%) and from Africa for 42 cases (21%), with 24 of these from Tanzania. Notifiable Diseases Report

22 Other vector-borne diseases Other vector-borne diseases notifiable over the period were infections with the alphaviruses getah and Sindbis; bunyaviruses including gan gan, maputta, termeil and trubanaman; and flaviviruses including yellow fever, Alfuy, Edge Hill, Kokobera, Kunjin, Stratford, Murray Valley encephalitis and Japanese encephalitis. Over the period there were four notifications of Sindbis. There were no notifications of the bunyaviruses. Of the flaviviruses, notifications were received for Kokobera, Kunjin, Murray Valley encephalitis, Japanese encephalitis and Stratford virus. No deaths or outbreaks were recorded from these conditions. The cases of Sindbis occurred in 25 in four adults from Mackay HSD aged between 22 and 57 years. Three were females and one was male. The cases occurred in ch (1 case), il (2 cases) and e (1 case). The source of acquisition was not recorded for these cases. There were 19 notifications of Kokobera over the period, in people aged 11 to 58 years. Eightyfour percent of cases were male. There were nine notifications in 24, five in 25 and five in 26. Of total notifications, 13 were NAHS residents (68%), with three notifications each from the other two area health services. Two cases, both in 24, had Australia recorded as the source of acquisition. One was from Innisfail HSD and one was from Sunshine Coast HSD. All other cases had no information on source of infection recorded. From 22 to 26 there were 15 notifications of Kunjin in adults aged from 2 to 73 years. Sixty percent of cases were male. Seven notifications occurred in 23; five in 24; two in 25; and one in 26. Nine notifications were in NAHS residents (6% of the total). Of these, four cases were recorded as locally acquired cases; one in 23 and two in 25 from Cairns HSD, and one case in 26 from Townsville HSD. All other cases, except one acquired in Nauru, had no information recorded on source of acquisition. There were eight notifications of Stratford virus one in 23, six in 24 and one in 26. Australia and East Timor were coded as the source for two of the infections in 24. All other notifications did not have information recorded on source of acquisition. The cases consisted of six males and two females, aged from 17 to 68 years. Five of the cases were residents of the NAHS (including two from Cape York HSD and two from Torres/NPA HSD), two were SAHS residents, and one was a CAHS resident. One locally acquired case of Murray Valley encephalitis was notified in 25, in a young adult from Mt Isa HSD. There were two notifications of Japanese encephalitis between 22 and 26. The first was in 23 in a young adult who acquired the infection while in Burma. The second was in 24 in an older adult who acquired the infection in Papua New Guinea. Both cases survived. There were 17 notifications of flavivirus infection between 22 and 26 where the specific flavivirus remained unidentified. These notifications were not analysed further. Vector-borne program and achievements The control of the mosquitoes involved in vector-borne illnesses requires a multifaceted approach which depends on effective collaboration between local and state governments. Queensland Health works to prevent and control these diseases through active interventions, the development of guidelines, mosquito and disease surveillance programs, health promotion activities, and funding for relevant research. 188 Notifiable Diseases Report Background image: Aedes aegypti

23 Aedes aegypti Guideline development and collaboration Queensland Health is actively involved in engaging community partners in the prevention and control of vector-borne illnesses. The North Queensland Dengue Fever Management Plan 25 21, 4 prepared by the Tropical Public Health Network, provides an important reference for health promotion, disease control and vector management in regards to dengue. The Queensland Health Guidelines to Prevent Mosquitoes and Biting Midges in New Development Areas 15 are available as a reference for developers and town planners. This document provides advice on the risks of creating new developments in close proximity to major breeding sites of the mosquito vectors of Ross River and Barmah Forest viruses. A Memorandum of Understanding is in place between Queensland Health, the Australian Quarantine and Inspection Service and Brisbane City Council. This outlines the responsibilities of each stakeholder should an invasion of exotic mosquitoes such as Aedes albopictus or Aedes aegypti occur. A strategic mosquito management plan for Queensland, including a specific Queensland dengue management sub-plan, is under development. These plans will provide strategic direction to local government and Queensland Health, to enable a collaborative approach to reduce the risks of vector-borne disease outbreaks in Queensland. Surveillance Queensland Health oversees various mosquito and disease surveillance programs. Surveillance programs for Ae. aegypti are carried out annually by Queensland Health and local governments in central and southern Queensland on a rotating, priority basis, to detect the presence of this mosquito vector and, if present, its density. Surveillance data are updated annually to inform Queensland Health, local government and research institutions on the spread of Ae. aegypti within Queensland. In 23 Ae. vigilax, a common vector of RRV and BFV on the coast, was found breeding in a salt pan adjacent to a residential area in Warwick. Mosquito breeding so far from the coast is an unusual event. Ongoing measures have been implemented by the local council to reduce the risk of disease to residents. Research Effective mosquito control relies on a good evidence base. Queensland Health provides annual funds to the Mosquito and Arbovirus Research Committee ( to enable research into mosquitoes and mosquito-borne diseases. The web-based Ross River Virus Early Detection System (RREDS), managed by the Queensland Institute of Medical Research, is one result of such funding, and has helped to make data on RRV infection notifications quickly and readily available to local councils. Notifiable Diseases Report

24 Photo credit Centers for Disease Control and Prevention / Collins FH (Centre for Global Health and Infectious Diseases, University of Notre Dame). Public Health Image Library a female Aedes aegypti mosquito. ID no [Online]. 26 [cited 3 29]. Available from: URL: References 1. Queensland Health (Tropical Population Health Services). Dengue fever. [Online]. 26 [cited 4 28].Available from: URL: disease.asp 2. World Health Organization. WHO report on global surveillance of epidemic-prone infectious diseases dengue and dengue haemorrhagic fever. [Online]. 2 [cited 15 28]. Available from: URL: ISR_2_1/en/index.html 3. Australian Bureau of Statistics. Table 1. Population distribution, Aboriginal and Torres Strait Islander Australians, 26. Cat. no Canberra: ABS. [Online]. 28 [cited 4 28]. Available at: URL: Document 4. Queensland Health (Tropical Public Health Unit Network). Dengue Fever Management Plan for North Queensland [Online]. [cited 31 28]. Available from: URL: health.qld.gov.au/dengue/managing_outbreaks/default.asp 5. World Health Organization. Dengue fever in Indonesia. Update 4. [Online]. 24 [cited 4 28]. Available from: URL: 6. Woodruff RE, Guest CS, Garner MG, Becker N, Lindsay M. Early warning of Ross River virus epidemics: combining surveillance data on climate and mosquitoes. Epidemiology 26;17(5): Kelly-Hope LA, Purdie DM, Kay BH. Ross River virus disease in Australia, , with analysis of risk factors associated with outbreaks. J Med Entomol 24;41(2): Tong S, Wu H. Climate variation and incidence of Ross River virus in Cairns, Australia: a timeseries analysis. Environ Health Perspect 21;19(12): Heymann DL, ed. Control of communicable diseases manual. 18th edn. Washington, DC: American Public Health Association, Liu C, Begg K, Johansen C, Whelan P, Kurucz N, Melville L. Communicable Diseases Network Australia National Arbovirus and Malaria Advisory Committee annual report, [Online]. Available from: URL: 11. Hanna JN, Ritchie SA, Eisen DP, Cooper RD, Brookes DL, Montgomery BL. An outbreak of Plasmodium vivax malaria in Far North Queensland, 22. Med J Aust 24;18: Brookes DL, Ritchie SA, van den Hurk AF, Fielding JR, Loewenthal MR. Plasmodium vivax malaria acquired in far North Queensland. Med J Aust 1997; 166: Jenkin GA, Ritchie SA, Hanna JN, Brown GV. Airport malaria in Cairns. Med J Aust 1997; 166: Merritt A, Ewald D, van den Hurk AF, Stephen Jr S, Langrell J. Malaria acquired in the Torres Strait. Commun Dis Intell 1998;22: Queensland Health. Guidelines to minimise mosquito and biting midge problems in new development areas. Brisbane: Queensland Health, 22. [Online]. Available from: URL: Notifiable Diseases Report Background image: Aedes aegypti