Meaning:
The short form of “流行病学调查” (liúxíngbìngxué diàochá), this term has frequently popped up in Chinese news recently. Translated as “epidemiological survey,” this refers to a medical survey conducted in an epidemic focus to discover the source of an infection, how the causative agent was transmitted, and the circumstances that gave rise to the disease. The findings are used to devise ways of preventing the disease from spreading. Individuals stricken by the disease and those persons who have had contact with them are interviewed; the latter also undergo laboratory testing. The survey may also include tests on objects from the environment.
Example:
A: 我昨天接到一个流调电话，居然问我银行账号。
Wǒ zuótiān jiēdào yīge liúdiào diànhuà，jūrán wèn wǒ yínháng zhànghào。
I received a phone call yesterday from someone who claimed to be collecting information for an epidemiological survey, and the guy asked for my bank account.
B: 流调人员不会问这种财务信息，打电话的一定是个骗子。
Liúdiào rényuán búhuì wèn zhèzhǒng cáiwù xìnxī，dǎdiànhuà de yīdìng shìge piànzi。
People won’t ask for financial information in an epidemiological survey. The caller must be a con artist.