Evans Travel Health

Whilst the world is focussed on the covid 19 virus and the impact on society; little has been discussed regarding other virus infections which we already know more about. Last year we were all aware of the issue of dengue infection, the poor performance of the Denvaxia vaccine and the increasing number of areas reporting raised levels of infection despite increasing public health responses.

Coming forward 12 months from the traditional rainy season in SE Asia we have reports of Aedes infections bringing with them the traditional infections of dengue, chikungunya and zika. Even countries such as Singapore with high healthcare standards are reporting high levels of dengue with 9000 cases so far this year and a weekly reporting of over 700 cases. Other countries such as Thailand are reporting infections from all 77 provinces with a country total so far of +14000 cases.

So why are we seeing the continued rise. One of the possible answers comes from scientists in India who have identified that the Aedes mosquito has adapted its egg laying to the sides of water containers.

Originally mosquito eggs were considered to be laid in a raft on the water surface before maturing and some such as Anopheles and Culex continue to do so. The Indian discovery was that Aedes now lays its eggs on the side of the water containers so they can mature in wet or dry conditions as the water levels adjust up and down, surviving for up to 9 months in dry conditions.

The virus itself enters the eggs and develops inside these cells during the lean period so they are available to be released at day 1 of the maturation.

If this research is confirmed then it may require new guidance to be issued, this will include the wiping and cleaning out of water containers every 2-3 days and not just emptying them.