第一期也称“急性期”，通常的特征是发热、肌肉疼痛（尤其是背痛）、头痛、寒战、食欲不振、恶心和呕吐。

The first, "acute", phase usually causes fever, muscle pain with prominent backache, headache, shivers, loss of appetite, and nausea or vomiting.

youdao

临床可表现为恶心、呕吐、腹痛、消化道出血、食欲不振、消瘦、头痛、头昏等。

The clinical manifestations included nausea, vomiting, abdominal pain, abdominal distention, gastrointestinal bleeding, poor appetite, marasmus, headache, dizziness and etc.

youdao

临床可表现为恶心、呕吐、腹痛、消化道出血、食欲不振、消瘦、头痛、头昏等。

The clinical manifestations included nausea, vomiting, abdominal pain, abdominal distention, gastrointestinal bleeding, poor appetite, marasmus, headache, dizziness and etc.

youdao