Since the introduction of childhood vaccination for diphtheria in 1932 and the widespread use of vaccines to prevent tetanus, pertussis (whooping cough) and poliomyelitis in the 1950s, deaths in Australia from vaccine preventable diseases (VPDs) have declined by more than 99%. It is important, however, that the downward trend in morbidity and mortality from VPDs is maintained and carefully monitored, and that changes are interpreted in relation to vaccination coverage.

High rates of absenteeism in a North Queensland primary school, due to eye irritation, fever, headache, and stomach pain, were reported to the Tropical Public Health Unit in October 2000. Subsequent investigation demonstrated that the symptoms were due to adenovirus infection. Symptoms were consistent with a diagnosis of pharyngoconjunctival fever. At the height of the outbreak, about 40 per cent of students were absent. There was a strong association between the development of symptoms, and having been swimming on a recent school camp. Adenovirus could not be isolated from swimming pool water from the resort where the camp had been held. However, when inspected the swimming pool was not adequately chlorinated or maintained. It is probable that adenovirus infection was transmitted via swimming pool water at the school camp, and the outbreak might have been avoided by higher standards of swimming pool maintenance.

Of 134 Queensland passengers on a cruise, 91 (67.9%) people reported various illnesses including 41 (30.6%) who reported diarrhoeal symptoms. Queensland passengers who ate while onshore at non-Australian ports were significantly more at risk of developing diarrhoeal symptoms than those who did not. Passengers were particularly at risk when they ate onshore while undertaking a tour compared with those who did not undertake this tour. Travellers should be warned of the possibility of contracting diarrhoeal illness from onshore catering.

Evidence concerning the effectiveness of Oka-based varicella vaccines when administered following exposure to varicella zoster virus in domestic and hospital settings is reviewed. The evidence appears to support post-exposure use of Oka-derived varicella vaccines in children within 3 days of rash onset in the index case. Despite vaccination, a small proportion will develop mild, but infectious, chickenpox, especially if they have been exposed in the household setting. Controlled studies of post-exposure prophylaxis in adults using both Varilrix and Varivax II are still needed. The applicability of this approach to disease control in health care facilities and in community settings warrants wider discussion.

An outbreak of laboratory confirmed measles involving 30 young adults and an infant is reported. Of the young adult cases, 17 (57%) were hospitalised. After a trip to India, the primary case returned to Sydney early in January 2001 and then visited Melbourne infecting several individuals. Secondary spread appears to have occurred at a nightclub. On the basis of RNA typing the measles strain involved is of genotype 'D'.

Since the inception of the National Mycobacterial Surveillance System (NMSS) in 1991, annual crude notification rates for tuberculosis have remained stable at between 5 and 6 per 100,000 population. In 1998, there was a total of 923 TB notifications in Australia of which 884 were new TB cases, and 39 relapsed cases. The corresponding annual crude notification rate for new and relapsed TB was 4.72 and 0.21 per 100,000 respectively. Seventy-seven percent of notifications that had a country of birth reported were overseas born. In keeping with trends observed over recent reporting years, the populations for which notified TB rates are highest include the overseas born from high prevalence countries and Indigenous Australians. The lowest rates of disease have continued to be reported in the non-Indigenous, Australian born population. Surveillance reports over the last seven years indicate that the rate of disease in this population is gradually declining.

Syphilis rates in the Kimberley region of far-northern Western Australia are among the highest in the nation. In 1986, a formal program of periodic syphilis screening was established. Decreasing syphilis rates since the early 1990s prompted, in 1999, re-evaluation of the value of periodic screening. All confirmed cases of syphilis identified in the Kimberley between January 1996 and early December 1999 as a result of syphilis serology were classified by reason for the test and staged according to disease progression. During the study period, 196 cases of syphilis (117 male, 79 female) were diagnosed; 14 (7.1%) were primary, 32 (16.3%) secondary and 150 (76.5%) latent. The periodic screening program contributed only about 10 per cent of cases, whereas testing as a result of sexually transmitted disease symptoms, sexually transmitted disease contact, institutional screening and other screening contributed the remaining cases. In January 2000, the periodic syphilis-screening program was discontinued. The effect of this policy change will be closely monitored using indicators to ensure that, should the decision not to screen prove to have been misjudged, any increase in syphilis incidence is detected early and managed appropriately.

Laboratory-supported influenza surveillance is important as part of pandemic preparedness, for identifying and isolating candidate vaccine strains, for supporting trials of anti-influenza drugs and for refining the influenza surveillance case definition in practice. This study describes the implementation of laboratory-supported influenza surveillance in Victorian sentinel general practices and provides an estimate of the proportion of patients with an influenza-like illness proven to have influenza. During 1998 and 1999, 25 sentinel general practices contributed clinical surveillance data and 16 metropolitan practices participated in laboratory surveillance. Serological, virus-antigen detection, virus culture and multiplex polymerase chain reaction procedures were used to establish the diagnosis of influenza. Two laboratories at major teaching hospitals in Melbourne provided additional data on influenza virus identification. General practice sentinel surveillance and laboratory identification of influenza provided similar data on the pattern of influenza in the community between May and September. The clinical suspicion of influenza was confirmed in 49 to 54 per cent of cases seen in general practice.

In late 1999, an outbreak of Bordetella pertussis occurred in a small town in North-West Western Australia. We undertook an investigation to describe the outbreak and to identify strategies to minimise the impact of future pertussis outbreaks in Australia. In November, people with respiratory symptoms were reviewed in an emergency pertussis clinic, which provided antibiotic treatment or prophylaxis. We conducted a school survey to enhance case ascertainment and followed up those attending the clinic by telephone. Fifty-nine cases of confirmed or probable B. pertussis infection were identified from 124 households (482 persons). Ages ranged from 5 months to 67 years, with children aged 9 to 11 years comprising 24 cases (41%). Early missed diagnoses and a school camp in September attended by 2 symptomatic children appeared to facilitate spread of infection, with the outbreak peak occurring in November. From immunisation records, childhood vaccine coverage in this sample was estimated at 96 per cent. All 21 cases of pertussis among the group under 10 years of age were at least partially vaccinated. There was only one laboratory confirmed case in the high-risk, under one-year of age category. Even in highly immunised populations periodic pertussis outbreaks are inevitable reflecting a vaccine efficacy of about 80 per cent and waning immunity with increasing age. Prevention of pertussis outbreaks depends not only on high vaccination coverage among young children but also early diagnosis and management of cases and their contacts. Clinicians should consider pertussis in the differential diagnosis of persistent cough illness in people of all ages--even those previously immunised.

We describe the epidemiological and clinical features of human Murray Valley encephalitis (MVE) and Kunjin (KUN) virus infections in Western Australia (WA) during March to July 2000. A case series was performed. For laboratory-confirmed cases, travel histories and clinical details were collected from patients, family members, friends or treating physicians. Surveillance data from the sentinel chicken program and climatic conditions were reviewed. Nine encephalitic cases of MVE were recorded. Eight were non-Aboriginal adults (age range, 25 to 79 years; 5 male, 3 female) and 1 was an Aboriginal boy. Four cases acquired infection in the Murchison and Midwest regions of WA from which no human cases of MVE have been reported previously. One of the 9 cases was fatal and 3 had severe neurological sequelae. Five non-encephalitic infections were also recorded, 3 MVE and 2 KUN. Encephalitis caused by MVE virus remains a serious problem with no improvement in clinical outcomes in the last 25 years. Excessive rainfall with widespread flooding in the northern two-thirds of WA provided ideal conditions for mosquito breeding and favoured southerly spread of the virus into new and more heavily populated areas. Surveillance in WA with sentinel chickens and mosquito trapping needs expansion to define the boundaries of MVE virus activity. To enable timely warnings to the public, and to institute mosquito control where feasible, continued surveillance in all Australian areas at risk is indicated.

In north Queensland the vector of dengue fever (Aedes aegypti) is present; hence any viraemic individual importing dengue has the potential to transmit the disease locally. In early 2000 approximately 2,000 personnel returned from East Timor to Townsville, north Queensland. Seven importations of dengue occurred and individual cases were viraemic for up to 6 days in Townsville. No subsequent local transmission occurred. There were 3 cases each of dengue type 2 and dengue type 3. One case could not be serotyped. A response, including mosquito control measures, was initiated in another 18 cases in which dengue fever was clinically suspected but which subsequently proved not to be dengue. The planning and processes undertaken to prevent local transmission of dengue in Townsville during an intense period are described.