Cook Islands dengue cases ‘declining’

Dengue cases in the Cook Islands are trending downward following the activation of Operation Namu26, and the health ministry remains open to exploring long-term natural control methods - such as dragonflies or Wolbachia bacteria - once the current outbreak is contained.

Since the official launch of Operation Namu26, Rarotonga has recorded 121 positive cases in the last 14 days - a fluctuating trend, according to Te Marae Ora (Ministry of Health).

Secretary of health Bob Williams said this indicates that dengue cases are declining.

Williams confirmed that as of Thursday (Cook Islands time) that Rarotonga has reported four positive cases and Aitutaki has reported six.

"Since activating Ops Namu26 on February 6 - Rarotonga recorded 121 positive cases across 14 of the last 15 days," Williams said.

He said the highest number recorded for Rarotonga was 19 positive cases on 9 February. Zero cases were recorded on Sunday, 15 February, and four new cases as of Thursday (Friday NZ time).

"The numbers have been fluctuating since the 6 February but it has been on a declining trend over the last 15 days," Williams said.

He said Aitutaki recorded 18 positive cases across seven of the last 15 days with six new cases recorded on Thursday.

Over the same period, Atiu recorded three positive cases across two days, Mauke recorded four positive cases across three days and Mangaia recorded nine positive cases across six days.

Williams said seven people were admitted in the last 15 days and all have been discharged.

Operation Namu26 was activated earlier this month due to the recent surge in dengue cases and the country's first dengue-related death on 2 February.

It is aimed to strengthen the national response with coordinated campaigns, which includes intensified spraying, surveillance and an island-wide clean up that was held on 13 February.

The key part of this operation is perifocal spraying - targeted insecticide application around homes of confirmed and suspected cases to suppress mosquito populations and limit further spread.

However, environmental group Te Ipukarea Society (TIS), in its weekly column published in this newspaper, encouraged the use of natural control methods -such as dragonflies - for destroying dengue mosquitoes.

"As aquatic nymphs, they live underwater for months or even years, consuming mosquito larvae before they ever have the chance to fly. Once they reach adulthood, they utilise specialised vision and high-speed manoeuvrability to catch adult mosquitoes mid-air. Supporting these predators can create a self-regulating ecosystem that does not require chemicals," TIS stated.

"While localised spraying may be necessary during a sudden, severe outbreak to provide a quick knockdown of the adult population, it is a short-term tactic rather than a long-term strategy."

Williams welcomed the suggestion as a long-term natural vector control measure.

Williams said this was the same reason the health ministry explored introducing Wolbachia-carrying mosquitoes. These insects infect the Aedes aegypti population with natural Wolbachia bacteria, which effectively blocks the transmission of the dengue, Zika and chikungunya viruses.

"Dragonflies is also a natural predator to mosquitos but are almost extinct due to many reasons."

He added that these are options to be explored, but not while we are "currently in an outbreak".