New Delhi: The increase this year in cases of the dreaded vector-borne chikungunya disease across the country, including Delhi, is the highest since 2006 -- when around 1,800 were tested positive, officials said. According to the National Vector Borne Disease Control Programme (NVBDCP), the central nodal agency for the prevention and control of vector borne, India has witnessed 9,990 suspected cases of the disease till now, with Karnataka reporting the highest 7,591 cases till July, 2016. In Delhi, though the civic bodies have reported only 20 Chikungunya cases till August 20, the sources from various hospitals in the national capital place the total positive cases over 400, with AIIMS alone recording 391 cases. However, the cases witnessed by AIIMS also includes patients from outside Delhi. "In suspected Chikungunya cases, we do not test all samples but start medication. Chikungunya is also caused by the same mosquito which causes dengue. It's just the lifestyle and the lack of precautions which is triggering the new chikungunya cases. People do not need to worry and just start taking precautions," A.C. Dhariwal, Director NVBDCP, told IANS on Tuesday. A senior doctor in AIIMS, said: "The cases of Chikungunya in Delhi this season is high, much higher than what civic bodies are quoting. AIIMS alone has witnessed 391 positive cases till August 20. Over 700 blood samples were received." The states generally affected by chikungunya are Andhra Pradesh, Karnataka, Maharasthra, Madhya Pradesh, Tamil Nadu, Gujarat and Kerala, Contradicting the statistics by the Delhi municipal corporations, the NVBDCP too stated that the total number of chikungunya cases recorded in Delhi hospitals stands at 256 as of now. Health experts said the increase in humidity was the sole reason in the increase in the number of cases, which if quite high in the last couple of years. According to the Safdarjung Hospital authorities, over 600 suspected chikungunya and dengue patients were received in the last two weeks. Chikungunya is a viral disease transmitted to humans by infected mosquitoes. It causes fever and severe joint pain. Other symptoms include muscle pain, headache, nausea, fatigue and rash. Joint pain is often debilitating and can vary in duration. The disease shares some clinical signs with dengue, and can be misdiagnosed in areas where dengue is common. There is no cure for the disease. Treatment is focused on relieving the symptoms. The proximity of mosquito breeding sites to human habitation is a significant risk factor for chikungunya. The Delhi government has set up 355 centres for check up of dengue and chikungunya.