A 25-year-old man, said by a government source to be a British national, has been arrested on suspicion of murder.
A lab in Wolverhampton is suspended as 43,000 people in England and Wales are potentially affected.
Personnel will be sent to NHS Lanarkshire and NHS Borders to relieve "significant pressure" ahead of the winter period.
The senior huntsman gave the hunting advice in private webinars that were leaked online.
Stephen Port was jailed after he raped and murdered four men using fatal overdoses of the drug GHB.