Tairāwhiti data, 21 July 2025
More measles. Three weeks of notifications; Hydatid case; Pertussis national epidemic; and winter illness.
Here comes the sun. I wrote after another rainy start. Then it rained again. We seem to be getting one wave after another of heavy rains…
Not many Tairāwhiti notifications in the last three weeks, but two of interest: our first TB cases in over a year and one for an eliminated disease (Hydatid); and Covid on the rise in July. But first a measles update.
Measles outbreak update
I wrote about the measles imported to the Wairarapa by returning travelers, stating that there were four cases. I was out of date. There were five, but I only got news of the fifth case after writing. All data are provisional!
The fifth case was infected overseas, so did not change the picture. Now we have local spread: all four susceptible close contacts who had been under quarantine have now become cases. So, showing the substantial risk of spread. But also potentially marking the end of this outbreak, as there are no more contacts in quarantine.
The first case (index) was reported on 7 July. They are considered the source for the three new cases were reported on 17 July. (Note the 10-day ‘usual’ incubation for this reporting interval.) The next day, the fourth and last contact in quarantine was confirmed as having measles; again from the index case.
So we had a 100% attack rate of the exposed who were measles-susceptibles. They were just under 15% of identified contacts, the remainder being considered immune by age, vaccine status, or blood test.
One of the new cases may have been infectious a day before entering quarantine on 11 July. So some new locations of interest in Fielding. If there was any spread from these, we may be seeing some more cases over the next week. And each new case can spread to more, or not, depending on exposures and susceptibility.
A graphic reminder of measles from Health NZ:
Note that a feature of measles is that fever is already present at time of rash onset.
The excellent 2025 NEJM review article on measles includes this table on consequences of measles infection (see article for references):
Measles status and imports
Until there is any new evidence of spread, measles remains eliminated from Aotearoa (NZ). We were WHO-certified as such in 2017, after three years without local spread. Some spread is expected after an import of this highly infectious virus. WHO allows up to 12 months of local spread.
The 2019 measles epidemic in NZ ended in early 2020, so we only just kept out measles-free status. The first outbreak was in Christchurch in March 2019, followed by multiple imports to Auckland.
For me, the 2019 epidemic reaffirmed the critical role of primary schools in measles spread. In 2019, we had close to 95% coverage with two doses of measles-mumps-rubella vaccine (MMR) in the primary school population. So, the outbreak was largely limited to unvaccinated adults and young children. And did not sustain, despite the many imports
We no longer have that immunity barrier with closer to 85% coverage in primary schools. Still good, but not good enough. Against measles it makes a big difference to have 5% or 10% susceptible. In the former, the effective reproduction number (R) become less than 1 and measles will not spread. But each case will, on average, spread to nearly to two others if 10% are susceptible: epidemic spread.
Many NZ birth cohorts, especially from the mid 1990s to the late 2000s are at increased risk as can be seen by the case distribution (from PHCC Brief of 30/4/24) :
Notifications
For my last data update on 30 June, I wrote
In the four weeks since my last report, we have had even fewer notifications. And no pertussis notifications, while at national level it has been on a rise.
Today’s update covers three weeks up to Sunday 20 July. In those 3 weeks, we saw an increase in Covid cases and hospitalisations (see below). Over the last three weeks we have only had 2, 4, and 3 non-Covid notifications: two cases of invasive pneumococcal diseases (IPD), and one each of Campylobacter, Giardia, Salmonella, and invasive Group A Streptococcus (iGAS):
The other three were for Hepatitis B, Tuberculosis (TB), and Hydatid disease (see below). The Hepatitis B was ‘not a case’, as the person had a chronic and not a new infection. I wrote about the TB case last week, comparing local and national notifications.
Hydatid disease
I wrote about Hydatid elimination on 23/8/24, after out last notification. NZ has been Hydatid-free since 2002. Our recent notifications have been recurrences. The latest notification was in a person without that prior history. They were born overseas, which is the likely source of the infection. (No likely local sources were identified in our interview.) But I was surprised that the Ministry of Primary Industries did not decide to investigate further to make sure that it was not locally acquired. It would ne a major issue for NZ if we found the organism re-established.
Pertussis national epidemic
I can again report no pertussis notifications - the last was end of May. But nationally, the pertussis epidemic continues, but with a drop in cases reported to 11 July:
But an increase in hospitalisations:
Covid-19
I did not include the Covid cases in my chart of local notifications as it would have drowned out the others. We had 0, 11, and 8 cases notified over the last three weeks. I chart them here with # reports to indicate how many times that person has notified Covid:
Note the jump in hospitalisations to four for each for the last two weeks. Three of the four from two weeks ago were infections acquired in hospital.
Compare the above chart with the last one I produced, noting that for the chart I could use the same scale for hospitalised cases, compared to 20 to 1 below:
When Covid first came to Tairāwhiti in early 2022, there were about 1 in 200 cases hospitalised. The change in ratio reflects reduced case notification; as the likelihood of getting hospitalised from Covid has not increased.
The monthly number of Covid hospitalisations from January to June are : 11, 6, 3, 3,1, 4, respectively. And we already have 8 for July.
The wastewater dashboard was only updated to week ending 6 July, showing a small drop, but still at higher levels:
National winter illness surveillance
The respiratory illness dashboard shows that for the week ending 13 July, the influenza peak has passed, and hospitalisations have dropped for the previous two weeks from high to medium activity; and the influenza-positive admissions have also declined from their peak:
Of note, Covid-hospitalisations with severe acute respiratory infection (SARI) in the Auckland sentinel site remained low.
In Tairāwhiti, we may have had a peak last week with several infected patients in the intensive care unit. We often get a later peak, due to our location and low population.
FluTracking data on prevalence of ‘fever and cough’, show moderate levels for the time of year, with a drop for the last two weeks up to 13 July: :
The FluTracking map shows symptoms reported locally at two sites in our district:
The red dot is from 1 report of 13 in postcode 4071 (red as >5%); the yellow is for Gisborne central from 4 symptomatic of 97 (4%, or just under the 5% threshold for red).
Next week
The STI annual report has been published by PHF Science (the new name for ESR) and the STI annual dashboard updated to 2024. Plan to review that annual report next week.
As always, I look forward to your feedback and suggestions; and any questions on the data. Thank-you for making it to the end!
Keep the reports coming Dr Oz.
I am interested in air pollution levels? Is it being measured and is there any legal requirement to measure that? I doubt coal burning is the problem it was in the urban area last century when we had winter smog