The reasoning: food poisoning by incubation period
| Incubation | Predominant symptoms | Agent | Typical vehicle |
|---|---|---|---|
| 1–6 h | Nausea, vomiting, cramps, no fever | *S. aureus (pre‑formed heat‑stable enterotoxin); B. cereus* emetic (cereulide) | Cream, milk products, cooked meat handled by carriers; fried rice (B. cereus) |
| 8–16 h | Watery diarrhoea, cramps | B. cereus diarrhoeal; *C. perfringens* | Meats, stews, gravies kept warm |
| 12–72 h | Fever, diarrhoea, vomiting | *Salmonella (non‑typhoidal), Campylobacter, Shigella* | Eggs, poultry, milk |
| 12–36 h (up to 72 h) | Descending flaccid paralysis, diplopia, ptosis, dysphagia, no fever, clear sensorium | *C. botulinum* (pre‑formed neurotoxin) | Home‑canned/preserved low‑acid foods; emergency: antitoxin, ventilation |
| 1–4 days | Watery diarrhoea | ETEC, norovirus | Water, salads |
| Minutes–1 h | Tingling, flushing | Chemical (scombroid, heavy metals) | Fish |