感染性疾病是由病原体（如细菌、病毒、真菌或寄生虫）引起的疾病。这些病原体可以通过空气、食物、水源、接触等途径传播给宿主。感染性疾病的症状取决于病原体的种类，可能包括发热、咳嗽、头痛、腹泻等。预防感染性疾病的关键措施包括接种疫苗、保持个人卫生、避免接触患者体液等。及时的诊断和治疗对于控制感染的传播和预防疾病的严重后果至关重要。

Infectious diseases are diseases caused by pathogens such as bacteria, viruses, fungi, or parasites. These pathogens can be transmitted to hosts through air, food, water, contact, etc. Symptoms of infectious diseases depend on the type of pathogen and may include fever, cough, headache, diarrhea, etc. Key measures to prevent infectious diseases include vaccination, maintaining personal hygiene, and avoiding contact with patient body fluids. Prompt diagnosis and treatment are critical to controlling the spread of infection and preventing serious consequences of the disease.