Is Zika here in Singapore for good?

Sep 13, 2016 06.13PM |

by Wan Ting Koh

IS ZIKA here to stay, and is it even possible to eradicate it fully? What about fogging – is it useful in the long term?

These were questions asked in Parliament yesterday (Sept 13) after two ministerial statements concerning the mosquito-borne disease were read out.

The first statement was by Health Minister Gan Kim Yong, who spoke about the current local situation of Zika and outlined strategies concerning the disease moving forward. He was followed by Minister for Environment and Water Resources Masagos Zulkifli who spoke about efforts to control the disease in terms of eradicating mosquito breeding grounds.

Both ministers responded to questions from eight Members of Parliament (MP), including the MP for MacPherson SMC Tin Pei Ling. MacPherson SMC is currently one of the seven Zika clusters in Singapore.

And it was Ms Tin who asked if Zika could be considered endemic and if it was possible to rid Singapore of the disease. The answer? In short, don’t know.

Mr Gan replied that it was “too early to tell” if it was endemic. He said that to focus on the terminology at this point in time is “not productive” and that the focus should be on the “immediate task”, which is vector control. Basically, to eradicate the source of the mosquitoes to prevent the transmission of the disease.

(Endemic diseases regularly occur among a certain region or place. The term is different from “epidemic” which describes an infectious disease that spreads rapidly to many people. Think SARS.)Why delay in detection?

Speaking of endemic, non-constituency MP Daniel Goh brought the house back to when Zika first started and asked why the 36 foreign workers, whose Zika infections the Ministry of Health (MOH) announced on Aug 28, were not detected earlier. Mr Gan said the symptoms were mild and that the infection is difficult to identify; the workers had also tested negative for dengue and chikungunya.

On Aug 23, a general practitioner at Sims Drive Medical Clinic, informed the MOH of an unusual increase in cases with fever, rash and joint pains. The cases were classified as mild as the initial hypothesis was a cluster of mild viral illness transmitted from person to person. MOH then made arrangements for the clinic to refer new cases to the Communicable Diseases Centre (CDC) for further testing and to start tracing past cases for review and testing if appropriate.

The ministry also communicated with nearby clinics and construction sites to be more vigilant and report cases to the ministry. Patient A, a 47-year-old Malaysian woman whose case was reported on Saturday (Aug 27), is considered the first case of locally transmitted Zika infection here. Patient A visited the same clinic as the construction workers on Aug 25 as she had developed fever, rash, and conjunctivitis. She was referred to the CDC at Tan Tock Seng Hospital, where she was tested positive for Zika.

The infections of the 36 foreign workers were identified via back-tracing.

As for its current Zika control measures, the G is now extending Zika testing beyond the clusters and providing a subsidy to all Singaporeans with Zika-like symptoms at public healthcare institutions, Mr Gan said. In addition, it is keeping doctors, especially GPs, which Mr Gan describes as the “key gatekeeper”, up to date with Zika developments. Zika was made a notifiable disease under the Infectious Diseases Act from January 5 this year, which means that MOH would immediately be alerted if any doctor or laboratory in Singapore detected a case of Zika.

Fog more often?

As for the Ministry of Environment and Water Resources, Mr Masagos said that the ministry will continue to employ more “boots on the ground” in terms of inspectors who check both household and construction sites for mosquito breeding grounds.

What about fogging? He said that routine and indiscriminate fogging was “not wise”. It is not a sustainable measure or effective against the local mosquito population, he added.

Fogging is only effective if the chemical has direct contact with the Aedes aegypti mosquito and it will have to be applied frequently as there would always be new batches of mosquitoes from breeding grounds that are not removed, said Mr Masagos.

Said Mr Masagos: “Fogging should only be used when there are Zika or dengue clusters or when the adult population [of Aedes mosquitoes] is observed to be high.”

In fact, fogging may cause a “build up of resistance in mosquitoes” which may then become immune to the insecticide. A more effective solution would be the “detection and removal of mosquito larvae”, he said.

Featured image from TMG file. 

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