THRIPS. They suck the sap. The infested leaves develop crinkles and curl upwards.

VIRUS: Susceptible to Mosaic Virus which can occur in land previously planted with either potatoes or tomatoes.

RED SPIDER MITE: First mottling on the upper leaves, which eventually turn bronze and fall off.

Organic soloution is to use unperfumed soapy water liberally onto your chilli plants every 14 to 20 days ( life cycle of thrips and mites.

I'd take no chances if you think its Virus because you are going to infect other plants such as strawberries, tomatoes and capsicums. Get fresh seeds or plants and dig in plenty of manure and some Neem before planting.

I've found this site quite interesting and they will answer questions online if non of the above seem to apply.