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Communicable Diseases Surveillance consists of data from several sources. The National Notifiable Diseases Surveillance System (NNDSS) is conducted under the auspices of the Communicable Diseases Network Australia New Zealand. The Virology and Serology Laboratory Reporting Scheme (LabVISE) is a sentinel surveillance scheme. The Australian Sentinel Practice Research Network (ASPREN) is a general practitioner-based sentinel surveillance scheme. In this report, data from the NNDSS are referred to as 'notifications' or 'cases', whereas those from ASPREN are referred to as 'consultations'. data from the LabVISE scheme are referred to as 'laboratory reports'.

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Vaccine preventable diseases

Rubella notifications remain low, with the number of cases having onset date in the first 3 months of 1998 being the lowest since 1992 (Figure 1). Most cases for 1998 have been in the 0 to 4 years (23%), 15 to 19 years (16%) and 20 to 24 years (18%) age groups. The male to female ratio was 1.2:1.

Figure 1. Notifications of rubella, 1991 to 1998, by month of onset



The number of notifications of pertussis continues to decline. A seasonal decrease in the number of cases is expected at this time of year (Figure 2). Most recent cases were notified for children aged under 15 years. Included were 15% in the 0 to 4 years age group, 21% aged 5 to 9 years and 16% aged 10 to 14 years.

Figure 2. Notifications of pertussis, 1992 to 1998, by month of onset



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Arboviruses

(see also Sentinel Chicken Surveillance Programme)
The number of new notifications of dengue has declined over the last month, 44 cases being recorded for the current reporting period, to bring the total for the year so far to 226. Only 4 of the current notifications had a recorded date of onset in April (Figure 3 ).

Figure 3. Notifications of dengue, 1991 to 1998, by month of onset



The number of new notifications for Barmah Forest virus infection and Ross River virus infection has also declined markedly in the last month (Figures 4 and 5). Small numbers of cases have been notified this year compared to previous years.

Figure 4. Notifications of Barmah Forest virus infection, 1995 to 1998, by month of onset



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Figure 5. Notifications of Ross River virus infection, 1991 to 1998, by month of onset



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Hepatitis A

The numbers of notifications for hepatitis A is remains above average (Figure 6); 71 of the 99 cases reported in the current period were males, including 50 males (50% of total) in the 20 to 44 years age range.

Figure 6. Notifications of hepatitis A, 1991 to 1998, by month of onset



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Respiratory diseases

(see also National Influenza Surveillance)

The number of laboratory reports of parainfluenza virus type 1 rose in March (Figure 7). Of the 71 reports received this period 27 (38%) were for infants under the age of one year, a total of 64 (90%) being for the under 5 years age group. We can expect more reports in the coming months as epidemics of this virus tend to occur in alternate years, the last outbreak being recorded in the winter of 1996. By contrast the number of reports of parainfluenza virus type 3 has continued to fall in recent months following the outbreak late last year.

Figure 7. Laboratory reports of parainfluenza virus types 1, 2 and 3, 1996 to 1998, by month of specimen collection




The number of reports of respiratory syncytial virus remain low which is usual for the time of year. However a rise can be expected in the winter months. Laboratory reports for this virus usually peak in July each year. Reports of Mycoplasma pneumoniae have remained at a sustained high level since late 1996.

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National Influenza Surveillance, 1998

Three types of data are included in National Influenza Surveillance, 1998. These include Sentinel General Practitioner Surveillance, Laboratory Surveillance and Absenteeism Surveillance. These are described below.

Sentinel General Practitioner Surveillance

Data will be included from four sources this season: ASPREN (the Australian Sentinel Practice Research Network); the Department of Health and Community Services, Victoria; the Department of Health, New South Wales; and Tropical Influenza Surveillance of the Department of Health and Community Services, Northern Territory.

Consultation rates for influenza like illness recorded by ASPREN have remained below 5 per 1,000 encounters for the year to date (Figure 8), which is usual for the time of year. The rates recorded by Tropical Influenza Surveillance also remain low. This is in contrast to previous years when an early peak in activity has been seen in the Northern Territory in February and March. The New South Wales Scheme also recorded a low consultation rate of 6.6 per 1,000 encounters (week ending May 2) as did the Victorian Scheme which recorded a rate of 1.8 per 1,000 encounters in April.

Laboratory Surveillance

Laboratory surveillance data from the Communicable Diseases Intelligence Virology and Serology Laboratory Reporting Scheme will be included in National Influenza Surveillance, 1997. The World Health Organization Collaborating Centre for Influenza Reference and Research will also contribute information on strains isolated.

A total of 103 laboratory reports of influenza have been received by the LabVISE scheme so far for 1998. Of these 76 (74%) were influenza A and 27 (26%) influenza B. Thirty one reports (30%) were for patients over the age 65 years.

For the year to date the WHO Collaborating Centre for Influenza Reference and Research has received only a small number of Australian influenza isolates. These have been mainly influenza A viruses which have all been characterised as A/Sydney/5/97-like. Two recent isolates of influenza B received from South Australia are yet to be analysed. A/Sydney-like viruses have also been received from New Zealand, Thailand and Singapore.

Absenteeism Surveillance

National absenteeism data will continue to be supplied by Australia Post and included in National Influenza Surveillance, 1997.

No absenteeism data is available this period.

Figure 8. Sentinel general practitioner influenza consultation rates, 1998, by scheme and week



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Figure 9. Laboratory reports of influenza, 1998, by type and month of specimen collection



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Gonococcal Surveillance

John Tapsall, The Prince of Wales Hospital, Randwick, NSW, 2031 for the Australian Gonococcal Surveillance Programme

The Australian Gonococcal Surveillance Programme (AGSP) reference laboratories in the States and Territories report data on sensitivity to an agreed 'core' group of antimicrobial agents quarterly. The antibiotics which are currently routinely included are the penicillins, ceftriaxone, ciprofloxacin and spectinomycin, all of which are administered as single dose regimens. When in vitro resistance to a recommended agent is demonstrated in 5% or more of isolates, it is usual to reconsider the inclusion of that agent in current treatment schedules. Additional data are also provided on other antibiotics from time to time. At present all laboratories also test isolates for the presence of high level resistance to the tetracyclines. Tetracyclines are however not a recommended therapy for gonorrhoea. Comparability of data is achieved by means of a standardised system of testing and a programme-specific quality assurance process. Because of the substantial geographic differences in susceptibility patterns in Australia, regional as well as aggregated data are presented.

Reporting period 1 July to 30 September 1997

The Australian Gonococcal Surveillance Programme (AGSP) laboratories examined 702 isolates of Neisseria gonorrhoeae for sensitivity to the penicillins, ceftriaxone, quinolones and spectinomycin and for high level resistance to the tetracyclines in the third quarter of 1997.

Penicillins

Resistance to this group of antibiotics (penicillin, ampicillin, amoxycillin) was present in a high proportion of isolates examined in Adelaide (46%) Sydney (33%) and Melbourne (29%) (Figure 10). In Brisbane and Perth the proportion of penicillin-resistant strains was 9% and 10% respectively. PPNG and relatively resistant isolates usually fail to respond to therapy with the penicillins. Those in the fully sensitive and less sensitive categories (minimal inhibitory concentration, MIC ≤0.5 mg/L) usually respond to a regimen of standard treatment with the penicillins.

There were 42 PPNG identified this reporting period (6% of all isolates). These were distributed widely with 6 PPNG reported from Melbourne, 12 from Sydney, 11 from Perth, 10 from Brisbane, 2 from the Northern Territory and a single PPNG from Adelaide. Some infections with PPNG were acquired locally but most were acquired in the Philippines, Papua New Guinea, Thailand, Malaysia, Borneo, Mauritius, Indonesia, Singapore and China.

Ninety one (13%) of all isolates were resistant to the penicillins by separate chromosomal mechanisms. These chromosomally mediated resistant N. gonorrhoeae (CMRNG) were most often reported in Sydney (69 strains, 28%), Melbourne (9 strains, 17.6%) and Adelaide (6 strains, 40%). No relatively resistant isolates were seen in the Northern Territory.

Ceftriaxone and spectinomycin

Although all isolates were sensitive to these injectable agents, a small number showed some decreased sensitivity to ceftriaxone.

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Quinolone antibiotics

This group of antibiotics includes ciprofloxacin, norfloxacin and enoxacin. Fifty seven isolates (8%) from throughout Australia had altered resistance to this group of antibiotics, 51 showing high level resistance. Forty six quinolone resistant N. gonorrhoeae (QRNG) (18%) were detected in Sydney and 5 (4%) in Perth, with one or two QRNG in the other centres.

An increase in rates of isolation of QRNG was noted in AGSP reports in 1997. The occurrence of QRNG in locally acquired infections especially in Sydney and Melbourne is of particular note. This high rate of locally acquired resistance continued in Sydney in the third quarter of 1997. Local acquisition of QRNG was also noted in Perth and Brisbane. Patients infected with QRNG overseas acquired infection in Japan, Taiwan, the United States of America, China, Thailand, Malaysia, Singapore and the Philippines.

Figure 10. Penicillin resistance of N. gonorrhoeae, Australia, 1 July to 30 September 1997, by region

PPNG Penicillinase producing Neisseria gonorrhoeae
RR Relatively resistant to penicillin, MIC ≥1 mg/L
LS Less sensitive to penicillin, MIC 0.06-0.5 mg/L
FS Fully sensitive to penicillin, MIC ≤ 0.03 mg/L

In the corresponding period of 1996, QRNG comprised 4% of all Australian isolates and the infections were acquired overseas. The quinolone agents are the oral agents most often used in centres where penicillins are ineffective. If resistance to the quinolones continues to increase, options for successful treatment will be substantially reduced.

High level tetracycline resistance

Thirty two tetracycline resistant N. gonorrhoeae (TRNG) were detected throughout Australia (5% of all strains) with isolates of this type again present in most centres. The highest proportion of TRNG was found in Perth where the 10 TRNG represented 9% of all isolates. TRNG were also prominent in Brisbane (11 isolates, 7%) but lower numbers were present in Sydney (6 isolates), Melbourne (1), Adelaide (2) and the Northern Territory (2). Indonesia was the most common place of acquisition, but TRNG were also acquired in Papua New Guinea, Mauritius, Thailand, Malaysia and Borneo. Local acquisition was also recorded.

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Sentinel Chicken Surveillance Programme

AK Broom,¹ J Azoulas,² L Hueston,³ JS Mackenzie,⁴ L Melville,⁵ DW Smith⁶ and PI Whelan⁷

Sentinel chicken flocks are used to monitor flavivirus activity in Australia. The main viruses of concern are Murray Valley encephalitis (MVE) and Kunjin which cause the potentially fatal disease Australian encephalitis in humans. Currently 26 flocks are maintained in the north of Western Australia, seven in the Northern Territory, nine in New South Wales and ten in Victoria. The flocks in Western Australia and the Northern Territory are tested year round but those in New South Wales and Victoria are tested only from November to March, during the main risk season. Results are coordinated by the Arbovirus Laboratory in Perth and reported bimonthly. For more information see 1998;22:7

Sentinel chicken serology was carried out for 26 of the 28 flocks in Western Australia in March 1998. There were three seroconversions in the Wyndham flock in early March and all three chickens had antibodies to MVE virus. There were no seroconversions in the Kununurra flock. However, a human case from Kununurra was confirmed in late February, caused by Kunjin virus. A confirmed case of encephalitis caused by MVE virus was reported in a young boy from the Wyndham area in March. The child is presently recovering in hospital.

Six flocks of sentinel chickens from the Northern Territory were also tested in our laboratory in March 1998. There was one new seroconversion to MVE virus in the Katherine flock, which was confirmed at a later bleed.

There have been no seroconversions to flaviviruses in March 1998 from the sentinel chicken flocks located in New South Wales, and the testing programme has now finished for this season. There were two seroconversions to Kunjin virus in chickens from the Mildura flock in Victoria in late March. These are the first flavivirus seroconversions in Victoria since 1991. The sentinel chicken surveillance programme will be continued in Victoria at least until the end of April 1998.

Corresponding author

1. Department of Microbiology, The University of Western Australia
2. Veterinary Research Institute, Victoria
3. Virology Department, Institute of Clinical Pathology and Medical Research, New South Wales
4. Department of Microbiology, The University of Queensland
5. Berrimah Agricultural Research Centre, Northern Territory
6. PathCentre, Western Australia
7. Department of Health and Community Services, Northern Territory

This report was published in Communicable Diseases Intelligence Vol 22 No 5, 14 May 1998.