sudden onset

The onset is sudden with cough, rusty sputum, marked fever and rigors.

突然发病，咳嗽、咳铁锈痰，高热及寒颤。

a sudden occurrence (or recurrence) of a disease.

疾病的突然发作或复发。

sudden start of an illness,etc

（疾病等突然的）侵袭,发作

Suddenly he fell ill and ran a high fever [temperature].

他突然病倒，发起高烧来。

Apparently a heart attack.

显然是心脏病突发。”

Because of its sudden start and rapid spread,

由于发病突然、传播迅速，

His stomach trouble flared up again.

他的胃病又突然发作了。

He died of a heart seizure.

他死于心脏病突然发作。

A sudden attack, recurrence, or intensification of a disease.

发作突然的发作、复发或疾病的加剧

The sudden appearance of a symptom such as coughing or sneezing.

突发如咳嗽或打喷嚏等病症的突然出现

The patient is given to sudden and inexplicable paroxysms of anger.

病人突然且无法解释地愤怒发作起来。

Late at night, Uncle Wang's stomach trouble flared up again.

深夜，王大伯的胃病又突然发作了。

He was suddenly cut off by a heart attack.

他因心脏病发作而突然死去。

P: By" fit" I mean I lose consciousness and fall on the ground on sudden.

病人：我所说的"突然发作"是指我突然不醒人事，摔倒地上。

Occurring suddenly and severely.Used of a disease.

急性的，暴发的突然且很严重的发生。用于疾病

The patient suddenly took a turn for the worse.

病人的病情突然恶化了。

A sudden change in the course of a disease or fever, toward either improvement or deterioration.

病情急转在疾病或发烧过程中病情转好或恶化的一种突然性转变

The plague broke out in that small town last summer, and about a hundred people died

去年夏天，那个小镇突然发生黑死病，近百人死亡。