LOS ANGELES — Much of the San Fernando Valley’s multibillion-dollar adult-movie business stopped production Thursday as it banned nearly four dozen actors and actresses from working after two tested positive for the AIDS virus, industry officials said.

Companies that churn out movies in what is estimated to be a $9 billion to $13 billion industry took a cautionary approach to the scare, which was revealed by the health agency that the industry created several years ago as part of its self-policing of sexually transmitted diseases. “At this point we have delayed production. We’re not sure when we will start again because it’s too soon to tell what the impact will be. Our main concern is the health and safety and welfare of our talent,” said Micsha Allen, marketing manager at VCA Pictures in Chatsworth.

The production halt — which includes most of the adult-film companies, but not all — will remain for at least 60 days while testing continues, but could extend beyond June.

“We have suspended production. We have no idea how long the information-gathering process will take,” said Wicked Pictures spokesman Daniel Metcalf.

The first performer to test positive, a male who performs under the name Darren James, worked with 12 women after being exposed to the virus while making a movie in Brazil during early March, said the Sherman Oaks-based nonprofit Adult Industry Medical Healthcare Foundation.

He was tested about every three weeks and eventually a test came up positive. Industry performers are tested for sexually transmitted diseases on a regular basis.

By late Thursday the foundation had identified 45 actors and actresses who subsequently either worked with James or the women he had sex with, said Sharon Mitchell, the foundation’s leader. The other positive test was from one women in the initial group of 12, known as the “first generation,” Mitchell said. Her name [Lara Roxx] was not released. All will be kept from working in the industry for about 60 days while undergoing testing, under its self-imposed quarantine policy.

“We’re in really good shape as far as containment. This is early detection,” said Mitchell, who worked in the industry for 25 years before earning a Ph.D. in human sexuality and helping establish the health center.

But that was little comfort to Randi Wright, an 18-year-old woman of suburban North Hills who began appearing in adult films a month ago to pay college tuition. On Monday she filmed a scene with an actor who is on the second-generation list.

“I’m really upset. I’m angry at the person who brought it into the industry.” Wright said she has tested negative so far. She did not want to use her real name because her family does not know what she has been doing.

One industry producer said some companies have a year’s worth of movies ready [Jill Kelly was quoted in other newspaper accounts as having said this], so that could soften the economic hit for the owners.

But the actors, actresses and others won’t be paid while production is shut down. Actors can make anywhere from $200 to $5,000 for a day’s work. The industry plays a stealth role in the San Fernando Valley’s economy. Jack Kyser, chief economist at the Los Angeles County Economic Development Corp., said it could be a $9 billion- to $10 billion-a-year business.

Mitchell said about 1,200 actors work in the business regularly and that an additional 300 pass through each year on a transitory basis.

There have been about a dozen AIDS-related incidents since 1989. The industry then began various forms of testing and the health center was established about five years ago.