The epidemiology of invasive pneumococcal disease in children in Far North Queensland.

OBJECTIVES: To describe the epidemiology of invasive pneumococcal disease in children under 5 years of age in Far North Queensland and to examine the potential impact of a seven- and 11-valent conjugate pneumococcal vaccine. METHODS: A review of all cases of invasive pneumococcal disease in children under 5 years of age in Far North Queensland over a 9 year period (1992-2000). The distribution of the serotypes of isolates causing invasive pneumococcal disease was compared with the serotypes contained in the two vaccines. RESULTS: The annual incidence in indigenous and non-indigenous children under 5 years of age was 163 (95% confidence interval (CI) 122-213) and 42 (95% CI 31-55) cases per 100 000 children, respectively. For children under 2 years of age, these figures were 297 (95% CI 208-411) and 71 (95% CI 49-100), respectively. There was a greater variety of serotypes isolated from indigenous children (n=17) than from non-indigenous children (n=9; P < 0.01). The serotypes within the seven-valent vaccine accounted for 62% (95% CI 46-75%) and 88% (95% CI 76-95%) of the isolates from indigenous and non-indigenous children, respectively (P < 0.01). Serotypes within the 11-valent vaccine accounted for 72% (95% CI 57-84%) of the isolates from indigenous children under 5 years of age, but did not account for any extra isolates from non-indigenous children. CONCLUSION: Although the seven- and 11-valent conjugate pneumococcal vaccines cover only approximately 60 and 70%, respectively, of the isolates that cause invasive disease in indigenous children in Far North Queensland, they nevertheless have the potential to prevent much morbidity in and hospitalization of these children. It will be essential to maintain surveillance following the introduction of conjugate pneumococcal vaccines so as to monitor changes in the incidence of invasive pneumococcal disease, particularly in high-risk children.

Recognising and responding to outbreaks of hepatitis A associated with child day-care centres.

OBJECTIVES: To assess the appropriateness of a protocol for recognising and responding to outbreaks of hepatitis A in child day-care centres and to determine if measles-mumps-rubella (MMR) vaccine was given too soon following the administration of normal human immunoglobulin (NIGH) to young children to control the outbreaks. DESIGN: Prospective surveillance to recognise cases of hepatitis A associated with, and outbreaks of hepatitis A in, day-care centres. MAIN OUTCOME MEASURES: The percentage of initial ('sentinel') cases of hepatitis A associated with day-care centres that were subsequently recognised as also being 'index' cases of outbreaks of hepatitis A in the centres, and the number of children 9-13 months of age when given NIGH who were subsequently given MMR less than three months later. RESULTS: Only 18 (16%) of the 114 sentinel day-care associated cases of hepatitis A were also index cases of outbreaks of hepatitis A in their respective centres. A total of 105 cases of hepatitis A were associated with the 18 outbreak centres; NIGH was administered to 928 (78%) of the attendee children, and to 105 (82%) of the susceptible staff, at the 18 centres. Three of the five children 9-13 months of age when given NIGH were given MMR less that three months later. CONCLUSIONS: Although outbreaks of hepatitis A were common events in day-care centres in north Queensland during the two-year study period, a single case of hepatitis A associated with a centre was a poor predictor of an outbreak within that centre. Precautions must be taken to ensure that live vaccines are not administered to young children too soon after NIGH.

The initial coverage and impact of the pneumococcal and influenza vaccination program for at-risk indigenous adults in Far North Queensland.

OBJECTIVES: To describe the initial coverage and impact of a pneumococcal and influenza vaccination program for at-risk Indigenous adults in Far North Queensland that formally commenced in 1996. DESIGN: Ascertainment of vaccine coverages, and prospective laboratory surveillance of invasive pneumococcal disease occurring in Indigenous adults in the region. MAIN OUTCOME MEASURES: Coverages of the first doses of both vaccines administered since 1995, and the incidence of invasive pneumococcal disease in Indigenous adults in the region between 1993-2000. RESULTS: Most (96% and 73%) of the Indigenous adults > or = 50 years of age received influenza and pneumococcal vaccines, respectively, for the first time between 1995-2000. Assuming that either 33% or 50% of Indigenous adults 15-49 years of age in Far North Queensland were eligible for vaccination, then either 109% or 72% of this population received influenza vaccine, and either 75% or 50% received pneumococcal vaccine, respectively, for the first time between 1995-2000. The incidence of vaccine-preventable invasive pneumococcal disease fell from 111 (95% confidence interval [CI] 77-154) cases per 100,000 per year in 1993/94 to 28 (95% CI 13-53) cases per 100,000 per year in 1999-2000 (p<0.05). CONCLUSION: Although there was a significant decline in the incidence of invasive pneumococcal disease, the vaccine coverages after five years of the program were suboptimal. Because of the difficulties in targeting the 15-49 years age group and because of unrecognised risk factors, we suggest that a universal Indigenous adult pneumococcal and influenza vaccination program should be considered.

The investigation of a 'cluster' of hepatitis B in teenagers from an indigenous community in North Queensland.

BACKGROUND: In early 1999, five teenagers from the same Indigenous community were notified as having hepatitis B. Hepatitis B vaccine should have been offered to this cohort of teenagers in a 'catch-up' program during the late 1980s when they were of pre-school age. OBJECTIVES: To determine the vaccination status of residents of the community born between 1981 and 1985 (inclusive) and to ascertain the prevalence of markers of hepatitis B infection and carriage in the incompletely vaccinated teenagers in this cohort. METHODS: Community health records were examined to identify all residents in the study cohort. Immunisation records were obtained from local hospital records and from a statewide computerised vaccination database. Serological tests for markers of hepatitis B infection and carriage were performed on blood samples from the incompletely vaccinated teenagers. RESULTS: Only 44% of 235 teenagers who had their vaccination status assessed were fully vaccinated. One hundred and eleven (47%) of the cohort had not received any hepatitis B vaccine. Over 90% of the incompletely vaccinated had been infected with the hepatitis B virus and 26% of these were hepatitis B carriers. CONCLUSIONS: Despite the availability of an effective hepatitis B vaccine and the recommendation for a catch-up program, the pre-school aged cohort of children at the community were not effectively targeted for vaccination. Hepatitis B remains a consequential infection in Indigenous communities in North Queensland. IMPLICATIONS: Initiatives to control hepatitis B need to be enhanced within existing maternal and child health, sexual health, alcohol and drug and chronic disease management programs.

Malaria and its implications for public health in Far North Queensland: a prospective study.

This prospective study's objectives were to describe the features of all episodes of malaria diagnosed in Far North Queensland (excluding the Torres Strait) and to assess how much of a threat they posed to the area's public health. Over a three-year period, 216 episodes of malaria were diagnosed (158 Plasmodium vivax and 68 P. falciparum infections). Most (82%) of the infections were acquired in Papua New Guinea (PNG). Approximately 70% of the episodes occurred in Australian citizens, about half of whom were in malaria-endemic countries for work; the remainder travelled abroad for recreation. Three-quarters of the Australian citizens with malaria had taken either no or inadequate prophylaxis. Australian citizens who had taken adequate prophylaxis were much less likely to develop P. falciparum than other types of malaria compared to those who took either no or inadequate prophylaxis (p = 0.01). Gametocytes were present in 121 (56%) of the episodes of malaria. Mosquito surveillance was carried out in response to 38 (31%) of these gametocytaemic episodes. Significant numbers of Anopheles farauti sensu lato mosquitoes were found close to the residence of a patient in 4 (11%) of these episodes. Only two occasions when local transmission could have possibly occurred were recognised. We do not believe malaria poses an important threat to the health of the public in Far North Queensland. Nevertheless, it remains an important problem for those who travel abroad to malarious areas.

Leptospirosis associated with severe pulmonary haemorrhage in Far North Queensland.

Pulmonary haemorrhage as a manifestation of leptospirosis is rarely diagnosed in developed countries. Five patients with proven leptospirosis associated with severe pulmonary haemorrhage presented to one hospital in Far North Queensland between January 1994 and June 1997. Four required admission to the intensive care unit and one patient died. Pulmonary haemorrhage is an uncommon but severe complication of leptospirosis and may be a source of diagnostic confusion in tropical areas of Australia.

Pneumococcal vaccination: an important strategy to prevent pneumonia in Aboriginal and Torres Strait Island adults.

The objective of the study was to examine the appropriateness of the National Health and Medical Research Council (NHMRC) recommendations concerning pneumococcal vaccination for Aboriginal and Torres Strait Island adults. Laboratory surveillance of invasive pneumococcal disease identified 95 cases acquired by adults 15 years of age and over in Far North Queensland from 1992 to 1995. The most common diagnosis was pneumonia (77 per cent). Sixty-one cases (64 per cent) occurred in Aboriginal and Torres Strait Island adults, who acquired the disease at a younger age (mean 40 years) than did other adults (mean 50 years). Most (93 per cent) of the Aboriginal and Torres Strait Island adults had at least one of the pre-existing medical conditions in the NHMRC criteria for pneumococcal vaccination. The most common was 'alcohol abuse' (62 per cent). Fifty-three (93 per cent) of the pneumococcal isolates from the Aboriginal and Torres Strait Island adults who had pre-existing conditions were serotyped. Fifty (94 per cent) belonged to types included in the currently available pneumococcal vaccine. We conclude that the NHMRC recommendations for pneumococcal vaccination are appropriate, considering the pattern of invasive pneumococcal disease that occurs in Aboriginal and Torres Strait Island adults in Far North Queensland. Because pneumococcal vaccination can reduce the pneumonia-associated morbidity and premature mortality experienced by Aboriginal and Torres Strait Island adults, the vaccine should be offered routinely to those considered to be at risk, particularly young men who have recently begun to consume hazardous amounts of alcohol, and recently diagnosed diabetics.

Plasmodium vivax malaria acquired in far north Queensland.

In February 1996, vivax malaria was diagnosed in a man from a remote community in far north Queensland who had not visited a malarious area for the past 19 years. Microscopy and DNA studies of blood from other residents of the community did not identify a source of infection. It was suspected the infection was transmitted by mosquitoes from a neighbour who had been infected in Papua New Guinea, but whose blood was not available for DNA tests.