What is black nose disease, a new chikungunya symptom?

Even though it is not a recognized medical term, Black Nose Disease refers to a noticeable skin pigmentation on the nose, also called Chik sign, which occurs rarely in a few patients infected with Chikungunya. It causes a dark discolouration on the nose. Experts say, it is considered a cutaneous manifestation of the condition and not a separate disease itself.