Florida couple David and Sharyn Linton have sought help after a snake bite on their honeymoon led to stage 4 lung disease. David Linton was bitten by a cottonmouth snake and diagnosed with stage 4 pulmonary fibrosis, a serious lung disease that makes it difficult for the lungs to function properly. The couple are seeking help raising the money needed for a life-saving double-lung transplant. Joseph Finley, a licensed venomous snake keeper, said snake bites like this are rare, with only about 6% of reported cases being caused by cottonmouth snakes.