“染上疾病”常见的英文表达有 contract a disease、catch a disease 或 come down with a disease。
contract a disease：较为正式和专业，常用于医学、科研等语境。例如：He contracted a rare disease during his trip abroad.（他在国外旅行期间染上了一种罕见的疾病。）
catch a disease：使用频率较高，在日常交流、新闻报道等场景都很常见。例如：Many children in the area have caught a flu-like disease.（这个地区的许多孩子都染上了一种类似流感的疾病。 ）
come down with a disease：口语化色彩较浓，强调开始出现疾病症状。例如：She came down with a cold last week.（她上周感冒了 。 ）