How we're keeping New Zealand free of pests
Pests of public health significance are also known as medical vectors. They are a public health concern because of the role they play in the transmission of diseases. They can carry pathogens from one host to another (such as viruses, bacteria, or protozoan parasites).
Vectors are generally considered to be invertebrate animals – specifically arthropods. However, vertebrates can also act as vectors. Numerous medical vectors of potential public health significance include mosquitoes, rats, fleas, lice, bed bugs, cockroaches, ticks, and mites.
New Zealand has remained free from many exotic diseases and disease vectors. Effective biosecurity and public health quarantine frameworks must be in place (including exclusion, surveillance, and response activities) and complement each other because there is a clear overlap in their core objectives.
Unwanted pests can have detrimental implications for both public health and biosecurity. Natural barriers such as New Zealand’s geographical separation from other countries support our quarantine and biosecurity frameworks. Both help to prevent the entry and establishment of new diseases or disease vectors.
Government agencies undertake several exclusion, response, and control activities. Some are undertaken by Ministry of Primary Industries (MPI) officers on behalf of the Ministry of Health. Local public health service officers undertake others.
Key border health activities
Key border health activities include:
- pre-border clearance of risk goods at overseas sites (eg, used vehicles checked in the country of origin)
- residual spraying with insecticides of aircraft that fly international routes (disinsection)
- inspection of ships (including yachts) arriving at New Zealand ports
- disinsection of untreated aircraft arriving at New Zealand airports and inspection of their high-risk cargo
- use approved transitional facilities to clear high-risk imported goods (eg, animal and animal products, food products, plant and plant products, used machinery and vehicles, wood and wood products, etc.) Import health standards specify what is required for certain goods and the facilities used to meet MPI standards.
Surveillance activities include public health services undertaking (or overseeing) surveillance and monitoring for exotic mosquitoes in or around international ports and airports. This includes:
- checking for the arrival/establishment of exotic mosquitoes of public health significance (eg, using a mix of larval traps, larval surveys, and adult traps to target different types of mosquitoes and lifecycle stages)
- identifying mosquito breeding sites and eliminating them or applying ongoing control measures
- recording mosquito species' distribution and habitat preference in New Zealand to help inform predictive modelling and other controls.
Te Whatu Ora contracts Southern Monitoring Services Limited to provide entomology identification services and technical advice to Te Whatu Ora and local public health services to support surveillance and response work. Southern Monitoring Services Limited also maintains a national mosquito surveillance database. Check out the Southern Monitoring Services Limited website for more information, including:
- information about the types of New Zealand and exotic mosquitoes
- sampling and surveillance resources for health protection officers
- border health surveillance data in monthly summary format (see the newsletters)
- information about other public health pests (eg, ticks, fleas).
Despite our best efforts to keep unwanted pests out of New Zealand, there is still a need to be able to quickly and effectively respond to suspected or confirmed pests such as exotic mosquitoes.
A mosquito response is an action taken to prevent the establishment and spread of an exotic mosquito of public health significance in New Zealand. Responses will vary in scale depending on whether it is:
- a mosquito detection (ie, a suspected but not yet confirmed exotic species)
- a mosquito interception (ie, the confirmation that adult mosquitoes or larvae detected at or before the New Zealand border (or in association with recently arrived travellers or goods such as at a transitional facility) are exotic mosquitoes of public health significance
- a mosquito incursion (confirmation of post-border detection and breeding of exotic mosquitoes of public health significance not previously known to be established in New Zealand and not associated with recently arrived travellers or goods).
Notifications from the public
Some responses can originate from reports or notifications from the public.
Key control measures undertaken include:
- removal or elimination of mosquito habitats – particularly around ports and airports
- source reduction of larval habitats (ie, removal of standing water sources)
- treatment of habitats (eg, public health officer using S-methoprene).