Saturday, September 03, 2016

Singapore MOH: 26 New Zika Cases & Preliminary Genetic Analysis


Today's update from Singapore's MOH/NEA adds 26 new cases along with an interesting data point; genetic analysis indicates the virus spreading there was probably imported from Asia, not from the outbreak in the Americas.

While both stem from the Asian lineage of the virus, last July in Emerging Microbes & Infect: Growing Genetic Diversity Of Zika Viruses In Latin America, researchers reported:

 . . . phylogenetic analysis revealed that the Asian lineage has evolved into two major lineages with high statistical support (Figures 1A and 1B), which we term the Oceanian and Latin American lineages.

Although the outbreak in the America's has been getting all of the attention, Zika has been spreading - often mistaken for Dengue or Chikungunya - in Southeast Asia and the Pacific Islands for years.

 A*STAR’s Bioinformatics Institute will be releasing more information on this finding in the near future.

        As of 12pm, 3 September, MOH has confirmed 26 new cases of locally transmitted Zika virus infection in Singapore. Of these, 24 cases are linked to the Aljunied Crescent/ Sims Drive/ Kallang Way/ Paya Lebar Way cluster. Two cases have no known links to any existing cluster. 

2.     The National Public Health Laboratory has worked with A*STAR’s Bioinformatics Institute to complete the sequencing analysis of the Zika virus found in two patients from the Aljunied Crescent/ Sims Drive cluster. The analysis found that the virus belongs to the Asian lineage and likely evolved from the strain that was already circulating in Southeast Asia. The virus from these two patients was not imported from South America. The research team will release more details shortly. 

Vector Control Update

3.    NEA has been continuing with vector control operations to control the Aedes mosquito population in Aljunied Crescent / Sims Drive / Paya Lebar Way / Kallang Way. As of 2 September, 57 breeding habitats – comprising 32 in homes and 25 in common areas/other premises – have been detected and destroyed. NEA officers and grassroots volunteers are also continuing with outreach in Paya Lebar Way and Kallang Way.

4.    NEA has also conducted vector control operations and outreach efforts in Bedok North Avenue. As of 2 September, 26 breeding habitats – comprising 17 in homes and 9 in common areas/other premises – have been detected and destroyed. Mosquito control measures are ongoing. NEA officers are continuing with outreach in this cluster as well.

5.    In these two cluster areas, indoor spraying of insecticides, outdoor fogging, and oiling and flushing of drains are continuing. In such areas with active transmission, outdoor fogging and indoor spraying and misting are both necessary because there may be infected adult mosquitoes in both outdoor and indoor areas that need to be destroyed before they bite and infect more people. These methods are, however, only effective if the insecticide has direct contact with the mosquitoes, and thus have to be repeated frequently as new batches of mosquitoes will continue to emerge until all breeding habitats are found and removed. Hence, routine fogging is not a sustainable vector control measure – source reduction is still a more effective and sustainable strategy.

6.    For non-cluster areas, the most effective mosquito control measure for keeping mosquito population low is still source reduction, through detecting and removing breeding habitats and killing larvae, as it eliminates the mosquitoes at the most vulnerable stage of their life cycle. This is in line with WHO’s recommendations for vector control.

7.    Community outreach activities over these two weekends across the island, including today, are ongoing to urge all residents to join in the collective efforts in the fight against Zika by doing the 5-step Mozzie Wipeout, removing stagnant water and not littering.

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