PERTUSSIS REPORT Data contained within this monthly report is based on information recorded on EpiSurv by public health service staff as at 12 December 213. Changes made to EpiSurv data after this date will not be reflected in this report. The results presented may be further updated and should be regarded as provisional. Summary In, 214 cases of pertussis were notified, including 94 confirmed, 95 probable, 9 suspect, and 16 cases still under investigation. The number of cases in November has decreased compared to the previous month (243 cases). Eighteen (8.4%) of the notified cases were aged less than 1 year. Twenty cases were hospitalised and no deaths were reported. Although weekly numbers had been trending downward since week 8 they have more or less been stable since week 16. Weekly notifications during November remain considerably lower than last year (Figure 1). In, the highest number of cases (excluding cases under investigation) were reported by Counties Manukau (39 cases), Canterbury (38 cases), and Nelson Marlborough (26 cases) DHBs. The overall rate in November was 4.5 per population (198 cases). The DHB with the highest rate was West Coast (21.3 per, 7 cases), followed by Nelson Marlborough (18.5 per, 26 cases), and Hutt Valley (9.7 per, 14 cases) DHBs. Since 1 January 213, 339 cases of pertussis have been notified, including 1518 confirmed, 167 probable, 135 suspect, and 67 cases still under investigation. Two hundred and fifty (7.4%) of the notified cases were aged less than 1 year. Two hundred and eleven cases were hospitalised and two deaths were reported. Since 1 January 213, high numbers of cumulative cases (excluding cases still under investigation) have been reported by Canterbury (548 cases), Nelson Marlborough (419 cases), and Waikato (284 cases) DHBs. The overall cumulative rate was 75. per (3323 cases). The DHB with the highest cumulative rate was Nelson Marlborough (297.8 per, 419 cases), followed by West Coast (182.4 per, 6 cases), and Canterbury (19.5 per, 548 cases) DHBs. This report summarises pertussis notifications for 213 (cumulative and a monthly summary). It incorporates the temporal distribution of cases, the distribution of cases by age, ethnicity (prioritised), and DHB, as well as hospitalisations and immunisation status. The case classification used in this report is specified on the last page. Case definitions have changed following the release of the Ministry of Health s Communicable Disease Control Manual 212 on 31 May 212. ESR Pertussis Report Page 1
Trends in pertussis notifications Figure 1: Number of pertussis notifications by week reported, 21 213 21 211 212 213 Number of pertussis notifications 18 16 14 12 8 6 4 2 Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Surveillance week (Month) Note: Includes confirmed, probable, suspect cases and notifications still under investigation. Figure 2: Number of pertussis notifications and hospitalisations by calendar month-year, 1998 to 3 7 Hospitalised Total notifications <1 year 5 Number of pertussis notifications 6 5 4 3 45 4 35 3 25 2 15 1 5 Number of hospitalisations 1998 1999 1 2 3 4 5 6 7 8 9 21 211 212 213 Month (Year) Note: Includes confirmed, probable, suspect cases and notifications still under investigation. ESR Pertussis Report Page 2
In the following pages, all analyses include confirmed, probable and suspect cases only. Notifications that are still under investigation are excluded. Figure 3: Comparative trend of the number of pertussis notifications by week reported, 21 213 Number of pertussis notifications (excluding under investigation) 18 16 14 12 8 6 4 2 21 211 212 213 Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Note: Includes confirmed, probable and suspect cases only. Surveillance week (Month) Age Table 1: Number of pertussis notifications and rate (cases per population) by age group, 213 Cumulative 1 notifications Age group (Years) All cases Rate 2 Hospitalisations New cases Hospitalisations <1 249 411. 114 18 11 1 4 521 27.4 17 3 2 5 9 351 12.4 8 18 1 1 14 29 72.3 3 24 1 15 19 132 42.4 3 8 2 29 291 46.3 6 12 3 39 389 69.8 13 16 4 49 493 78.8 15 35 2 5 59 335 58.9 4 15 2 6 69 27 48.3 12 1 1 7+ 146 34.7 14 12 Overall 3323 75. 29 198 2 1 Cumulative notifications since 1 January 213, includes confirmed, probable and suspect cases only. 2 Rate of pertussis cases per population calculated using 212 mid-year population estimates. ESR Pertussis Report Page 3
Figure 4: Pertussis rate (cases per population) by age group and ethnicity, 213 Pertussis rate (cases per population). 9. 8. 7. 6. 5. 4. 3... Māori Asian * * Pacific Peoples MELAA. <1 1 4 5 14 15+ Age group (Years) Note: Cumulative notifications since 1 January 213, includes confirmed, probable and suspect cases only. Denominator data used to determine rates are based on the proportion of people in each ethnic group from the estimated resident 6 census population applied to the 212 mid-year population estimates from Statistics New Zealand. * Rate based on fewer than five cases. Ethnicity Table 2: Number of pertussis notifications and rate (cases per population) by ethnicity (prioritised), 213 Cumulative 1 notifications Ethnicity All cases (Rate 2 ) Hosp 3 (% 4 ) <1 year 5 (Rate 2 ) New cases Hosp 3 <1 year 5 Māori 454 (7.1) 55 12.1 81 (496.) 14 4 2 Pacific Peoples 211 (79.1) 49 23.2 53 (864.2) 18 7 9 Asian 15 (25.7) 14 13.3 9 (171.) 5 3 2 MELAA 15 (39.7) 1 - European or Other 2389 (77.7) 84 3.5 99 (38.6) 139 6 4 Unknown 149 7 6-22 1 Overall 3323 (75.) 29 6.3 249 (41.1) 198 2 18 1 Cumulative notifications since 1 January 213, includes confirmed, probable and suspect cases only. 2 Rate of pertussis cases per population. Denominator data used to determine rates are based on the proportion of people in each ethnic group from the estimated resident 6 census population applied to the 212 mid-year population estimates from Statistics New Zealand. Where fewer than five cases have been notified a rate has not been calculated. 3 Number of hospitalised notifications. 4 Percentage of hospitalised notifications. 5 Number of notifications in the <1 year age group. ESR Pertussis Report Page 4
District health board Figure 5: Pertussis rate (cases per population) by district health board, 213 District health board Nelson Marlborough West Coast Canterbury Tairawhiti Wairarapa Northland Southern Waikato South Canterbury Whanganui Capital and Coast Hutt Valley MidCentral Taranaki Bay of Plenty Counties Manukau Auckland Waitemata Lakes Hawke's Bay. 5.. 15.. 25. 3. 35. Pertussis rate (cases per population) Note: Cumulative notifications since 1 January 213, includes confirmed, probable and suspect cases only. Rate of pertussis cases per population calculated using 212 mid-year population estimates. Immunisation status of confirmed notifications Table 3: Immunisation status of confirmed pertussis notifications, Age group Total cases One dose Two Three Four Five Vaccinated (no dose info) Not vaccinated Unknown <6wks 1 4 4 6wks 2mths 5 1 1 3 3 4mths 2 2 5mths 3yrs 16 1 6 9 4 1yrs 13 1 1 3 1 5 2 11+ yrs 54 2 1 7 11 33 Total 94 4 3 7 3 1 9 32 35 Note: Immunisation status has been extracted from EpiSurv. Health professionals may use a range of sources to update immunisation status including the National Immunisation Register, parental recall and Well Child book records. 1 Children aged <6 weeks are not eligible for immunisation. ESR Pertussis Report Page 5
Table 4: Immunisation status of confirmed pertussis notifications, 213 Age group Total cases One dose Two Three Four Five Vaccinated (no dose info) Not vaccinated Unknown <6wks 1 27 26 1 6wks 2mths 66 32 3 2 24 5 3 4mths 32 11 12 6 3 5mths 3yrs 285 7 5 141 16 14 83 19 4 1yrs 35 3 4 34 91 12 35 92 34 11+ yrs 83 24 5 9 1 24 94 128 59 Total 1518 77 29 184 117 36 145 359 571 Note: Immunisation status has been extracted from EpiSurv. Health professionals may use a range of sources to update immunisation status including the National Immunisation Register, parental recall and Well Child book records. 1 Children aged <6 weeks are not eligible for immunisation. ESR Pertussis Report Page 6
Appendix Table 5: Number of pertussis notifications and rate (cases per population) by district health board, 213 Cumulative 1 notifications District health board All cases Rate 2 Hosp 3 <1 year 4 New cases Hosp 3 <1 year 4 Northland 146 92.2 18 2 3 1 Waitemata 244 44.1 2 18 17 3 1 Auckland 218 47.2 22 16 8 Counties Manukau 269 52.9 75 58 39 13 11 Waikato 284 76.7 14 16 11 1 Lakes 28 27.2 4 3 Bay of Plenty 135 63.6 5 8 1 1 Tairawhiti 5 16.8 4 Taranaki 73 66.2 3 6 4 Hawke's Bay 38 24.5 2 3 1 Whanganui 46 73.6 5 5 MidCentral 114 67.4 5 9 Hutt Valley 14 72.1 6 9 14 1 2 Capital and Coast 216 72.7 8 16 12 2 Wairarapa 39 96. 2 Nelson Marlborough 419 297.8 8 24 26 West Coast 6 182.4 1 2 7 Canterbury 548 19.5 7 18 38 1 1 South Canterbury 43 76. 3 1 Southern 249 8.9 3 11 8 Total 3323 75. 29 249 198 2 18 1 Cumulative notifications since 1 January 213, includes confirmed, probable and suspect cases only. 2 Rate of pertussis cases per population calculated using 212 mid-year population estimates. 3 Number of hospitalised notifications. 4 Number of cases in the <1 year age group. ESR Pertussis Report Page 7
Figure 6: Pertussis rate (cases per population) by age group (<1 year vs. 1+ years), 1997 212 <1 year 1+ years Pertussis rate (cases per population) 8. 7. 6. 5. 4. 3.... 1997 1998 1999 1 2 3 4 5 6 7 8 9 21 211 212 Year Note: Includes confirmed, probable and suspect cases only. Rate of pertussis cases per population calculated using mid-year population estimates. Figure 7: Trends in pertussis rates (cases per population) by age group and ethnicity, 3 212 <1 year 5 14 years Māori Pacific Peoples Māori Pacific Peoples Pertussis rate (cases per population) 9 8 7 6 5 4 3 Asian/MELAA European or Other 3 4 5 6 7 8 9 21 211 212 9 8 7 6 5 4 3 Asian/MELAA European or Other 3 4 5 6 7 8 9 21 211 212 1 4 years 15+ years Pertussis rate (cases per population) 9 8 7 6 5 4 3 Māori Pacific Peoples Asian/MELAA European or Other 3 4 5 6 7 8 9 21 211 212 Year 9 8 7 6 5 4 3 Māori Asian/MELAA Pacific Peoples European or Other 3 4 5 6 7 8 9 21 211 212 Year Note: Includes confirmed, probable and suspect cases only. Rate of pertussis cases per population calculated using mid-year population estimates. ESR Pertussis Report Page 8
Figure 8: Monthly pertussis rate (cases per population) by district health board, since January 212 Note: Includes confirmed, probable and suspect cases only. Figure 9: Monthly pertussis cases by district health board, since January 212 Note: Includes confirmed, probable and suspect cases only. ESR Pertussis Report Page 9
Case classification for pertussis notification in New Zealand up to 3 May 212 Confirmed A clinically compatible illness that is laboratory confirmed by isolation of Bordetella pertussis from a pernasal swab, or epidemiologically linked to a confirmed case. Probable Cough lasting longer than two weeks and one or more of the following: Paroxysmal cough Cough ending in vomiting or apnoea Inspiratory whoop for which there is no other known cause. Suspect In children under five years of age, any paroxysmal cough with whoop, vomiting or apnoea for which there is no other known cause. Other Status recorded as under investigation or suspect case. Notifications Include confirmed cases, probable, and other as specified above. Case classification for pertussis notification in New Zealand from 31 May 212 Confirmed A clinically compatible illness that is laboratory confirmed by isolation of B. pertussis or detection of B. pertussis nucleic acid, preferably from a nasopharyngeal swab, or is epidemiologically linked to a confirmed case. Probable A clinically compatible illness with a high B. pertussis IgA test or a significant increase in antibody levels between paired sera at the same laboratory OR A cough lasting longer than two weeks and with one or more of the following, for which there is no other known cause: Paroxysmal cough Cough ending in vomiting or apnoea Inspiratory whoop Suspect In children under five years of age any paroxysmal cough with whoop, vomiting or apnoea for which there is no other known cause. Under A case that has been notified, but information is not yet available to classify it as suspect, investigation probable or confirmed. Notifications Include confirmed cases, probable, suspect and under investigation as specified above. This report is available at: http://www.surv.esr.cri.nz/surveillance/pertussisrpt.php ESR Pertussis Report Page 1