The number of AIDS cases reported in the United States and Puerto Rico jumped by 86 cases in the first week of August, the result of federal public health officers being sent to three cities to find cases, officials of the federal Centers for Disease Control said yesterday.

The new figures show 2,094 reported cases of Acquired Immune Deficiency Syndrome, with 805 deaths. An additional 123 cases were reported from 20 foreign countries.

The disease, which debilitates victims' immune systems, shows no sign of decreasing, authorities said.

"The incidence is apparently increasing," said Dr. Richard Selik, an epidemiologist in the centers' surveillance section. "It's difficult to distinguish how much of the increase is due to improved reporting and how much is due to more cases, but there is a true increase in incidence of some value."

"We're getting more reports, but we're also doing more surveillance work," said Betty Hooper, a spokeswoman for the centers. The number of cases in August showed a larger-than-average increase from prior months, but Hooper said improved reporting and new attention by state health departments may account for most of it. In July, there was an average of 53 cases of AIDS reported each week.

In the last six weeks, the federal centers have sent four public health officers to Miami, Los Angeles and San Francisco to comb through hospital records for possible AIDS victims, said Rick Altice, a member of the center's surveillance unit. The effort has increased the number of reported cases, he said.

Currently, 18 states have made Acquired Immune Deficiency Syndrome a reportable disease, which means that health officials can be penalized for not reporting cases to the federal government. Twenty other states have legislation pending on the issue and all but a handful of states are considering such action, according to a survey conducted by the CDC.

Health officials in the District of Columbia, Virginia and Maryland all are required to report AIDS cases.

The District of Columbia, which initially balked at providing even the initials of victims to the federal government for fear of loss of privacy, is reporting the cases now. Concern over confidentiality has prompted the CDC to begin substituting a letter and number code for names so researchers cannot reconstruct the patients' names, Altice said.

The disease primarily strikes homosexual men and intravenous drug abusers, but infants, hemophiliacs and others receiving blood transfusions suspected of having been contaminated with AIDS have been found to be victims of the illness.

Despite protests from the Haitian government and medical officials, the CDC still considers Haitians to be among the population groups at special risk of contracting AIDS. Although a meeting was held last week at the centers to develop a study regarding the link between Haitians and AIDS, the designation has not been dropped. "The fact is that 5.1 percent of the victims are Haitians who do not admit to homosexuality or intravenous drug use," said Hooper. "It's an unfortunate situation because the study could take a year to complete."