Disease Outbreaks - New Zealand

Measures to curb the spread of pertussis disease in an outbreak are as follows: 

· Timely immunisations of infants - Infants are the most vulnerable to pertussis infection. There is little or no protective immunity transferred maternally via placenta or through breast milk. Young babies not fully immune to pertussis are potentially at serious risk of the disease. Adults and older children in the household can pose a particular threat to babies if they spread pertussis. When a baby has had the scheduled immunisations on time, their level of protection puts them at a strong advantage to fight off the disease should they come into contact with it. Infants are at highest risk for effects of disease such as apnoea, pneumonia, seizures, and encephalopathy. Mortality rates are higher in the first year of life than any other age group. Complications in adults include bacterial pneumonia and rib fracture. Young age, lack of timely immunisation, low socio-economic status, unhealthy lifestyle habits in the home and premature delivery are all associated with an increased risk of fatal pertussis disease. A common trend to delay infant immunisation in the mistaken belief that they are too young to receive vaccines is leaving significant numbers of infants at higher risk of contracting pertussis.  
 
· Recommend a booster dose to adults - This will increase community immunity and reduce transmission. Immunity levels are short lived from both vaccination and natural infection. As immunity wanes people become firstly susceptible to colonisation by the pertussis bacteria, then experience symptoms from mild clinical disease through to more severe disease. Even though symptoms may be mild the disease can still be transmitted to those vulnerable. Remember to mention though that a Boostrix® will not be funded for adults.   

· Passive Immunisation - International recommendations for a pertussis outbreak situation, include offering vaccine to women who are pregnant (in some situations) [2] or during the postnatal period. This allows protection for the mother but more importantly protection for the newborn baby against the disease until 6 months of age when they have received all the scheduled doses of vaccine themselves.

· Community Immunity –

1. Adults planning pregnancy, both parents and other adults living in the household of families with young children are recommended to have a pertussis containing vaccine. Evidence shows family members, particularly parents, were identified as the source of infection in more than 50% of cases and presumed so at a higher percentage.[3]

2. Adults working with children specifically teachers or childcare employees are recommended to have a pertussis containing vaccine.

3. Health care workers, particularly those working with neonates and vulnerable children. E.g. Nurses working in paediatric wards, oncology, NICU or SCBU are strongly encouraged to be vaccinated prior to commencing work.   

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[1] NZ Immunisation Handbook 2006 pg 168

[2] General Recommendations on Immunization Chapter (Pink Book)2006

[3] The Australian Handbook 9th ed. 2008

June 2009- Pertussis: 115 cases of pertussis were notified in June 2009, compared to 108 notifications in the preceding month and 25 notifications in same month of the previous year (Figure 2). There were 34 (29.6%) laboratory-confirmed cases. The highest numbers of cases were reported from Canterbury (14 cases), Waikato (13 cases) and Auckland (12 cases) DHBs. For the 12 month period ending 30 June 2009, the highest incidence rates were reported from West Coast (74.1 per 100 000 population, 24 cases) and Nelson Marlborough (71.5 per 100 000, 97 cases) DHBs compared to a national rate of 21.9 per 100 000 population. The current 12 month rate by age group was highest amongst infants aged less than one year (128.0 per 100 000 population, 82 cases), followed by children in the 1-4 years age group (37.3 per 100 000, 88 cases).

Non-seasonal influenza: In New Zealand, non seasonal influenza A (H1N1) became notifiable on 29 April 2009 and 1,191 cases of influenza A (H1N1) were notified in June 2009 (758 confirmed, 39 probable, 363 suspect and 31 under investigation).The preceding month reported 21 cases. There were 86 hospitalised cases. The highest number of cases was recorded from Capital and Coast DHB (264 cases) followed by Canterbury (179 cases) and Hutt Valley (137 cases) DHBs. For the latest information on the non seasonal influenza A (H1N1) situation in New Zealand see http://www.moh.govt.nz/influenza-a-h1n1.

May 2009- Pertussis: 109 cases of pertussis were notified in May 2009, compared to 98 notifications in the preceding month and 26 notifications in same month of the previous year (Figure 2). There were 23 (21.1%) laboratory-confirmed cases. The highest numbers of cases were reported from Canterbury (27 cases), Waitemata (15) and Waikato (11) DHBs. For the 12 month period ending 31 May2009, the highest incidence rates were reported from West Coast (74.1 per 100 000 population, 24 cases) and Nelson Marlborough (68.5 per 100 000, 93 cases) DHBs compared to a national rate of 19.9 per 100 000 population. The current 12 month rate by age group was highest amongst infants aged less than one year (117.1 per 100 000 population, 75 cases), followed by children in the 1-4 years age group (32.6 per 100 000, 77 cases). - Taken from the Monthly Notifiable Disease Surveillance report- May 2009

Pertussis epidemics occur about every 4-5 years. In the last epidemic (1999-2001), there were nearly 7,000 cases notified. Since 2001, four infants have died aged 3, 4 & 5 weeks and <12 weeks.

Regional differences are marked. Very high monthly rates (notifications per 100,000) are reported from Southland (304), Nelson Marlborough (214), Otago (125) and South Canterbury (102). In the North Island, the highest rates are from Waikato (94) with Northland, Lakes, Bay of Plenty and Tairawhiti all reporting rates around (40).

Meningococcal B invasive disease and the new MeNZB™ vaccine
New Zealand is facing an epidemic of our own home grown strain of Meningitis disease. A new vaccine has been developed to combat this disease and the first regions have started immunising.

Click here to read more. http://www.moh.govt.nz/meningococcal (NZ Ministry of Health provides regular updates on Meningococcal disease)