Observations on surveillance

by Professor David Penman and Professor Stephen Goldson
Aerial view of a typical suburb

Professor David R Penman
Director, David Penman & Associates

Professor Stephen L Goldson FRSNZ
Affiliate member, Koi Tū
Principal Scientist, AgResearch and Professor, Bio-Protection Research Centre, Lincoln University

Between us, having spent 100 years on pest management and biosecurity, we and all New Zealanders are now confronting the invisible new scourge of the COVID-19 virus pandemic.  The severe implications of this pestilence for all of humankind have now become appallingly obvious.  To many, what was once seen as some kind theoretical threat has suddenly been realised. Neither, contrary to expectation, has there been any cheerful off-the-shelf solutions.

Based on wide-ranging and brilliant new technologies, science has made very fast progress in identifying the qualities of this new disease which has threatening traits.  In particular this includes its egregious ability to spread.  This of course has led to extensive commentary and, sadly in some places, disinformation and misunderstanding.  Irrespective, the world waits almost by the hour for news of the arrival of therapies and vaccines.

Thus, the threat to New Zealand from COVID-19 is obvious. But now, almost incredibly, by controlling its establishment and spread, we seem to be taking advantage of our remote geographical location and thereby side-stepping its worst impacts. This country has had time to react and it has. Also, due to its ‘late-arrival’ in New Zealand, we have been able to see what COVID-19 is doing elsewhere.  And there is another upside. Dealing with invasive pests and diseases is familiar to New Zealanders who have spent decades confronting the threat of foot and mouth disease, fruit flies, Mycoplasma bovis and numerous other species that we have intercepted and stopped.  Of course, COVID-19 is in its own horrible league. Yet the familiarity of New Zealanders with such exigencies is extensive.

The current invasion of COVID-19 is outside of the biosecurity system but the implementation of an effective surveillance programme could benefit from lessons learned. These have included the development of sampling strategies and associated models for the detection of risk organisms at low levels of occurrence (primarily animal diseases, plant pests and pathogens).  Irrespective, surveillance is a key component. Hence with regard to the virus, the ‘testing, testing, testing’ mantra is about sampling and not census and this requires design and tactics.

Stratified sampling of target groups or areas is essential but can only do so much. However, it is a vital start and must be carried out before we exit Alert Level 4. But we must recognise that such approaches do not necessarily reflect a population at large and if there is ongoing occurrence during winter, then we will need to go further. For that, sampling must be greatly extended to get an estimate of what is going on in an entire population, not just its apparent hot spots.

Anyway, we have done it before – surveillance of incursions have been effective in developing containment and eradication programmes for insect pests such as fruit flies, lymantrid moths and a parade of others.  A more immediate comparison might be with the current efforts to eradicate Mycoplasma bovis.

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