Authorities warned hikers and campers that two squirrels carrying bubonic plague had been found in a southern California wilderness area. Moise Mizrahi, a spokesman for the San Diego County Department of Environmental Health, said crews were posting signs and handing out fliers after routine tests on squirrels at William Heise County Park in southeastern California determined they were infected.

He said the plague, a bacterial infection, can be transmitted from rodent fleas to animals and then to humans and is potentially deadly if not treated.

French researchers have discovered a rare, new HIV strain that can avoid detection with standard screening tests. The strain was found in a 40-year-old Cameroonian women who died of AIDS complications in 1995.

The strain has only been found in three other cases, all in Cameroon. According to lead researchers Francois Simon and Francoise Brun-Vezinet of the Bichat Hospital, the strain is related to both common HIV and SIV strains. Following analysis of the woman's blood in Paris, researchers observed that the virus belonged to neither group M--the predominant group--or group O.

They also noticed that the new strain had hallmarks of SIV. The scientists, who report their findings in the September issue of Nature Medicine, then tested 700 other frozen blood samples from people in Cameroon, finding that three other HIV samples matched the woman's. The HIV variant does not appear to have any selective advantage that would cause it to spread at a different rate than the predominant strains. Anthony S. Fauci, director of the National Institutes of Allergy and Infectious Diseases, called the new strain an "interesting curiosity" and said it was unlikely that the new strain would pose a public health threat. [Washington Post, P. A2; Weiss, Rick]

According to the Ethiopian National HIV/AIDS Control Program, almost 2.5 million people in the nation have HIV or AIDS, out of a total population of 58 million. The program estimated that 60 percent of the country's male population aged 15 to 49 years could die by 2009.

The World Health Organization estimated that there were about 200,000 HIV infections in the country last year, although the national control program reported only 21,000 AIDS cases in 1996. (Source: Addis Tribune Online)

In certain areas of Africa, one in four adults is infected with the virus that causes AIDS, and around the world the disease now rivals the greatest epidemics of history, according to a UN report. In the first country-by-country analysis of the disease, the United Nations said that last year 30 million people worldwide were infected with HIV, the AIDS virus, and that 21 million were in Africa.

In 13 of those countries, HIV has infected at least 10 percent of adults, and in Botswana and Zimbabwe, a quarter of adults are infected, a rate that even an expert described as "shocking."

AIDS is hitting Africa so fiercely that it now rivals the great epidemics of history--the Black Death of the Middle Ages that killed 20 million people, or one-quarter of Europe's population, in four years and the influenza pandemic of 1918-1919 that killed 20 million people, including half a million Americans.

Infection rates exceed one in three adults in some major African cities and reach 70 percent of women tested in some prenatal clinics. Worldwide last year, 5.6 million people were newly infected while 2.3 million died from AIDS.

LONDON -- A potentially lethal micro-organism, dubbed the "cell from hell," has begun to invade the North Sea. The cells, called pfiesteria piscicida, were originally a harmless plant. But in North Carolina, pollution has caused pfiesteria to mutate into a highly toxic killer preying on fish.

When pfiesteria attacks, it uses its poison to stun the fish, who lose all orientation. Then the organism proceeds to eat the fish alive. American fishermen complain that pfiesteria kills millions of fish. Marine experts warn that the same could happen in the North Sea.

Humans became targets too. More and more people living and working along the U.S. coast began to suffer from open sores which would not heal, had headaches and memory loss. The culprit: pfiesteria. In one experiment, pfiesteria cells were put into human blood. They immediately attacked and swallowed all blood cells.

The organism is almost indestructible. When pfiesteria cysts are put into sulphuric acid they survive for 30 minutes. A human body thrown into sulphuric acid would quickly dissolve.

One of the greatest triumphs of human ingenuity has been our progress against infectious disease. Today, we have only the mute testimony of millions of gravestones to remind us of the lives tragically cut short by scarlet fever, polio, smallpox, or rampant infections of childbirth. But these mighty conquests are of small comfort to Christy and Chad Gimmestad of Evans, Colo. Their 16-month-old daughter, Anna Grace, died in late 1996 during a worrisome outbreak of E. coli, a vicious microbe unknown until 1980. E. coli's rampage continues: It sickened 16 people in Colorado last year.

Nor is the miracle of penicillin and other antibiotics much consolation to the families of the 33 people who have died of rampaging strep A infections since December in Texas. And our successes treating the terrible lung disease tuberculosis may not have much meaning for California teenager Debi French. In 1993, French came down with a TB infection potent enough to fight off even today's miracle drugs. Only after a two-year struggle--and the surgical removal of nearly half of her right lung--did the high-schooler come out on top in this battle of humanity vs. the microbes. On Mar. 18, the World Health Organization warned that TB could infect 1 billion more people in the next 20 years.

Scarcely a week goes by without a report of some dire and growing threat. Mysterious hantaviruses are causing gruesome deaths in the West. Potent new forms of TB are emerging in Tennessee and Kentucky. Staph germs that don't respond to the most commonly used antibiotics are spreading from Chicago hospitals to the surrounding community.

In fact, more than 30 dangerous new infectious agents have been discovered in the past two decades. The death rate in the U.S. from infections jumped nearly 58% between 1980 and 1992. Researchers estimate that hospital-acquired infections alone are responsible for a staggering $4.5 billion in annual U.S. health-care costs.

The situation is far grimmer elsewhere. With malaria, TB, and dengue fever on the rise, microbes are now causing one-third of the world's 50 million-plus deaths each year. "We are seeing a global resurgence of infectious diseases," U.S. Surgeon General David Satcher warned Congress on Mar. 3.

Experts say humanity is now at a crucial turning point in the millennia-old war against microbes. One reason is the explosion in world population. Another is air travel--the deadliest infectious diseases are only a plane ride away from New York, London, or Tokyo.

Most ominously, though, microbes have been hard at work in a deadly race, mutating to create potent new defenses far beyond the reach of many existing treatments. "We have never been more vulnerable," says microbiologist and Nobel laureate Joshua Lederberg. "When I go through all the adaptations [made by] the microbial world to make a living at our expense, I sometimes wonder how we're still here."