The usual campaign signs are absent; the glass door is locked, and new visitors are scrutinized before being let in. This squat building on a commercial stretch of Los Feliz Boulevard off the Golden State Freeway is headquarters for Proposition 64, a multimillion-dollar test of America's attitude toward AIDS.

Acquired immune deficiency syndrome, a deadly disease that destroys the body's resistance to cancers, pneumonia and other illnesses, is an increasingly emotional issue as the number of its victims -- and its incidence outside the male homosexual community -- grows.

But in California, political extremist Lyndon H. LaRouche Jr. and his followers have sometimes obscured an already difficult problem.

LaRouche's signature-gatherers put Proposition 64 on the ballot. His headquarters on Los Feliz, staff members say, has been so besieged by death threats and vandalism that it has been forced to take unusual security measures.

The group's name, the Prevent AIDS NOW Initiative Committee, or PANIC, indicates the tenor of its campaign.

LaRouche's reputation has galvanized opinion among many people who know little about the initiative. People questioned at random in a busy Los Angeles business area recently identified Proposition 64 as "the LaRouche initiative."

"Anything LaRouche is for, I'm against," said retired business executive Jim Willson. Screenwriter Mike McDonald called LaRouche "a maniac and his initiative would create a public health disaster."

The state's large homosexual community is almost unanimous in opposition. "It is definitely going to drive the disease underground," said Ron Rose, a Hollywood office administrator and AIDS patient. "If people know their names will be reported, they will not go in for treatment."

The latest polls show a majority of likely voters opposed to the initiative, although much of the general electorate remains either undecided or uninformed about Proposition 64. Many may make up their minds based on the 83-word summary on their ballots.

Proposition 64's supporters, led by PANIC, say it would require any individual who carries the AIDS virus, even without the disease's symptoms, to be reported to state authorities and barred from schools or jobs in restaurants. State officials could quarantine such carriers.

Current medical tests can detect antibodies indicating that an individual has been exposed to the AIDS virus. Studies indicate that about 20 percent of those exposed develop the disease within five years; that percentage is expected to climb when tests are able to examine longer periods after exposure.

Although AIDS appears to be spreading to other groups -- about 300,000 Californians are now thought to carry the virus -- most of its victims are male homosexuals. In the last five years, 24,500 AIDS cases have been reported in the United States, and as of Aug. 31, 2,796 people have died of AIDS in California.

Gay activists argue that the initiative would lend an air of legitimacy to job discrimination against homosexuals, and public health authorities say it would deter victims from seeing doctors, who would be required to report them. This, they say, would further the spread of the disease undetected.

Proposition 64 is opposed by the 34,000-member California Medical Association and most statewide elected officials, Democrats or Republicans. The two contenders for the U.S. Senate, Sen. Alan Cranston (D) and Rep. Edwin V.W. Zschau (R), have signed the official voters-guide argument against it. Nearly every major newspaper has recommended a "no" vote.

The lastest Los Angeles Times Poll of 990 likely voters showed 60 percent opposed and 26 percent in favor, with 14 percent undecided. An ABC-Washington Post poll of 772 likely voters reported 52 percent opposed, 31 percent in favor and 17 percent undecided.

In 1978, a similar coalition of gay-rights groups and mainstream politicians helped win a 57 percent vote against the Briggs initiative, which would have barred avowed homosexuals or anyone who advocated gay rights from teaching in public schools.

Some leaders opposed to Proposition 64 think this campaign could again reinvigorate the gay-rights movement, which has flagged in recent years.

Torie Osborn, 35, a small business consultant who worked in the campaign against the Briggs initiative, said "a wide coalition is now developing that could be helpful in creating a political realignment."

But Osborn, now southern California coordinator of the No On 64/Stop LaRouche campaign, said she is worried by the large undecided vote and some fairground informal polls that show opinion evenly divided on the measure.

The opposition has raised $ 1.2 million and hopes to find $ 1.5 million more for a radio and television blitz emphasizing medical opinion against the initiative.

Campaign leaders had considered focusing on LaRouche's bizarre politics -- he has called former vice president Walter F. Mondale a "Soviet agent of influence" -- but polls revealed that to many voters, "it really doesn't matter who is behind the initiative," Osborn said.

Khushro Ghandhi, 35, a long-time West Coast activist in the LaRouche organization who is PANIC president, insists that if the initiative does not pass now, AIDS will have spread so widely in two years that voters will be demanding even tougher controls.

"Since I am fortunate to be influential in some scientific circles internationally, I have used that influence to organize support for AIDS research," said LaRouche in a 24-page pamphlet prepared by the campaign. "We have a simple choice: Spend money to stop AIDS, or die."

Larouche, whose political organization is based in Virginia, suggests that politicians are letting budget considerations stand in the way of measures such as Proposition 64. Ghandhi said the campaign plans to distribute more than 1 million copies of the pamphlet. He would not comment on other media strategies.

The initiative's opponents argue that AIDS should not be treated like typhoid or other contagious diseases because it can be transmitted, according to the federal Centers for Disease Control, only by intimate sexual contact or sharing of blood through contaminated needles, transfusions or pregnancy.

Proposition 64 supporters respond by pointing out the uncertainty that surrounds research involving any new disease.

Rep. William E. Dannemeyer (R-Calif.), one of the few elected officials supporting Proposition 64, accepts the general medical view that AIDS cannot be transmitted casually. That does not mean, he says, that the initiative's reporting requirements are unnecessary.

Dannemeyer's legislative counsel Missy Hancock said Colorado has required AIDS reporting for several months, with no sign that disease victims have gone underground.

George Ware, a Colorado state disease control specialist, said the state's new regulation does not include Proposition 64's employment restrictions, but it does require even private clinics to report the names and addresses of AIDS virus carriers.

"We've seen no drop in reporting," said Ware, whose state has recorded 168 AIDS-related deaths. "In some places, there seems to be an increase."

Tom Kennedy, a spokesman for the California Medical Association, said his organization considers the ban on virus carriers in teaching and restaurant jobs the most damaging part of Proposition 64, because research shows such people would not be a danger to customers and students they serve. Text of Proposition 64

Acquired Immune Deficiency Syndrome (AIDS) -- Declares AIDS virus carrier a contagious condition, subject to quarantine and reportable disease regulation. Fiscal impact: The measure's cost could vary greatly depending upon its interpretation by health officers and courts. If existing discretionary communicable disease controls were applied to AIDS, given the current state of medical knowledge, there would be no substantial change in state and local costs. If measure were interpreted to require added disease controls, cost could range to hundreds of millions of dollars per year depending on measures taken.