KATHMANDU: An unstable weather pattern in the Mt Everest region has started taking its toll on the world climbers as many of them on the Nepal side have been gripped by altitude sickness and some forced to abandon their expedition. According to health workers and expedition organisers, over 400 climbers and mountain workers complained of high altitude sickness after Khumbu region witnessed an unstable weather this spring season. Following the arrival of a lot of inexperienced support staff as well as foreigners in the region, the cases of high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE) were also increasing every day, they added. “At least ten climbers have already returned to Kathmandu while 17 climbers and 10 high altitude workers were evacuated from Khumbu region till date after they complained of HAPE and HACE.” Himalayan Guides Nepal treks informed that five climbers abandoned their bid to scale Mt Everest after they suffered from altitude sickness. A Malaysian climber flew back to Kathmandu after suffering from HAPE, Pemba Sherpa, manager at Seven Summit Treks said. He added that most of the high altitude workers also complained of sickness in the recent days. According to Snowy Horizon Treks, an Iranian mountaineer has also abandoned his bid on Mt Everest after he was evacuated from Camp I to the Base Camp. Lakpa Norbu Sherpa who works with a team of medical doctors at the Mt Everest base camp informed that his clinic had treated at least 140 patients in the last three weeks. “At least 17 patients including 12 foreign climbers were evacuated from Base Camp and higher camps,” he told The Himalayan Times over phone. Bhuwan Acharya, an official at Feriche-based aid-post run by Himalayan Rescue Association said that at least 320 patients received treatment at the Aid-post while more than 10 persons have been visiting the facility daily for treatment. “Seven foreigners and three high altitude Sherpa workers were also evacuated from Feriche,” he added. Doctors noted that altitude sickness was a major challenge to climbers in the Everest region. According to them, Symptoms of altitude sickness include nausea, vomiting, loss of appetite, insomnia, persistent headache, dizziness, light headache, disorientation and drunken gait, weakness, fatigue, lassitude, heavy legs, slight swelling of hands and face, breathlessness and breathing irregularly, as well as reduced urine output among others. The Department of Tourism issued climbing permits to over 400 climbers including 289 for Mt Everest. More than 500 high altitude workers and base camp staff also joined the teams attempting to climb Mt Everest, Mt Lhotse and Mt Nuptse this season.