A potentially fatal dengue-fever like virus has emerged in the country, according to the Health Ministry.
The Chikungunya virus is thought to be transmitted by the Asian tiger or forest-day mosquito (Aedes albopictus), said Dr Vu Sinh Nam , the deputy head of the Department of Preventive Medicine.

What does the phrase "
forest-day" mean here?
Why we use "the" in "
The Chikungunya virus"? Does this mean that there are many kinds of Chikungunya virus?