forest-day mosquito and the Chikungunya virus

[anhnha]

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?

 

[5jj]

What does the phrase " forest-day" mean here?

The mosquito lives/breeds in forests and bites during the day. The words are not normally hyphenated.

 

[emsr2d2]

Why we use "the" in "The Chikungunya virus"? Does this mean that there are many kinds of Chikungunya virus?

No, it means the exact opposite. By specifying "the Ch... virus", it is stating that that is the name of just one individual virus. If there were many kinds of Ch... virus, it would have said "One of the Ch... viruses is spread by ..." or "One of the forms of the Ch... virus is spread by ..."