Name the causative agent and the main symptom of each of the following diseases.
(i) Filariasis
(ii) Rabies
(iii) Chicken pox

(i) Filariasis is caused by an infection of a nematode parasite, filariae of the order Filariidae. Most commonly it is caused by the Wuchereria bancrofti. The most common symptom is edema with thickening of the skin and underlying tissues i.e. elephantiasis.

(ii) Rabies is a viral disease caused by the Rabies virus. These viruses are spread by biting another animal or a person. The most common symptom of rabies is flu-like symptoms, which include fever, muscle weakness, and tingling, headache. Other symptoms include anxiety, insomnia, agitation, hallucinations etc.

(iii) Chickenpox is caused by the Varicella virus, which is spread through contact. The main symptom includes blister-like rash which first appears on the face and trunk and then spreads throughout the body.