Vector-borne disease notifications

This section provides the latest statistics on dengue fever, malaria and other vector-borne disease notifications in New Zealand.

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320 cases of vector-borne diseases were notified in 2014
Overseas travel accounted for most vector-borne disease cases
Increase in number of dengue fever notifications
33 cases of malaria were notified in 2014

320 cases of vector-borne diseases were notified in 2014

In 2014, there were 320 cases of vector-borne diseases notified in New Zealand [1]. These included:

  • 178 cases of dengue fever
  • 57 cases of Zika fever
  • 44 case of Chikungunya fever
  • 33 cases of malaria
  • 6 cases of Rickettsial disease
  • 1 cases of Ross River fever
  • 1 case of cysticercosis.

Annual notifications of total vector-borne diseases ranged from 103 to 320 cases from 2010 to 2014. Vector-borne diseases have showed an increasing trend since 2011 (Figure 1).

Dengue fever and malaria accounted for 81 percent of the total vector-borne disease notifications in New Zealand from 2010 to 2014.

Figure 1

Overseas travel accounted for most vector-borne disease cases

Monitoring travel-related factors helps determine whether the diseases are contracted within New Zealand or from elsewhere. 

Overseas travelers contributed to almost all of vector-borne disease notifications in 2010–2014.  Almost all of them had travelled during the disease incubation period (Figure 2).

However, overseas travel only accounted for a small proportion of Rickettsial disease notifications. This suggests that most people diagnosed with Rickettsial disease were infected in New Zealand.  This is consistent with other studies in New Zealand [2-4].

Figure 2

Source: ESR [1]

Increase in number of dengue fever notifications

In 2014, 178 cases of dengue fever were notified in New Zealand, an increase of two thirds compared to 106 cases in 2013.[1].

Dengue fever notifications annually fluctuated between 42 and 178 cases from 2010 to 2014 (Figure 3).  Almost all of these cases had a history of overseas travel, suggesting that they were infected outside New Zealand. 

Figure 3

Source: ESR [1]

33 cases of malaria were notified in 2014

In 2014, there were 33 notifications of malaria in New Zealand. Annual malaria notifications fluctuated between 33 and 52 from 2010 to 2014 (Figure 4).

Travel history data from 2010 to 2014 show that almost all of malaria cases had a history of overseas travel. Around 82 percent of the travel happened during the incubation period. This suggests that they were infected outside New Zealand. Some types of malaria can stay at a dormant stage and hide in the liver for weeks and even years. A relapse may then occur at a later date.

Figure 4

Source: ESR [1]

References

1. ESR. 2015. Notifiable and Other Diseases in New Zealand: Annual Report 2014. Porirua: The Institute of Environmental Science and Research Ltd. Available online: https://surv.esr.cri.nz/surveillance/annual_surveillance.php

2. Kelly P, Roberts S, Fournier P-E. 2005. A review of emerging flea-borne bacterial pathogens in New Zealand. New Zealand Medical Journal 118(1208).

3. Kelly P, Rolain J-M, Raoult D. 2005. Prevalence of human pathogens in cat and dog fleas in New Zealand. New Zealand Medical Journal 118(1226): U1754. 

4. Roberts S, Hill P, Croxson M, Austin P, McKay J, Ellis-Pegler R. 2001. The evidence for rickettsial disease arising in New Zealand. New Zealand Medical Journal 114(1138): 372-374.