Pests of public health significance

A range of border control activities are undertaken to keep pests of public health significance out of New Zealand, or to respond to interceptions or incursions of such pests (eg, exotic mosquitoes).

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. There are numerous medical vectors of potential public health significance including mosquitoes, rats, fleas, lice, bed bugs, cockroaches, ticks, and mites.

New Zealand has remained free from many exotic diseases and disease vectors. It is important that effective biosecurity and public health quarantine frameworks are 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 to both public health and biosecurity. Our quarantine and biosecurity frameworks are supported by natural barriers such as New Zealand’s geographical separation from other countries. Both help to prevent the entry and establishment of new diseases or disease vectors.

A number of exclusion, response, and control activities are undertaken by government agencies. Some are undertaken by Ministry of Primary Industries (MPI) officers on behalf of the Ministry of Health. Others are undertaken by local public health unit officers.   

Exclusion 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 of approved transitional facilities to clear high risk imported goods (eg, animals 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 units 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 the distribution and habitat preference of mosquito species in New Zealand to help inform predictive modelling and other controls.

The Ministry of Health contracts Southern Monitoring Services Limited to provide entomology identification services and technical advice to the Ministry and local public health units 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).

Response activities

Despite our best efforts to keep unwanted pests out of New Zealand, there is a still a need to be able to quickly and effectively respond to suspected or confirmed pests such as exotic mosquitoes.

A mosquito response is action taken to prevent the establishment and spread in New Zealand of an exotic mosquito of public health significance. 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 (ie, 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).

Some responses can originate from reports or notifications from the public.

  • Notifications of suspected exotic mosquitoes should be made to and followed up by local public health units.
  • Reports from the public about exotic organisms other than mosquitoes should be made to the MPI hotline 0800 809 966 or via the MPI website.

Controls

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).
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