Infectious Diseases

Between 1.8 million and 5.7 million Americans caught pandemic H1N1 influenza this spring, as many as 21,000 were hospitalized, and perhaps 800 died, according to new estimates by researchers at the Centers for Disease Control and Prevention. The revised numbers suggest that even larger numbers will become infected during this flu season. Estimates, as opposed to specific numbers, are the best data available. Many cases are not reported to public health authorities, and the CDC stopped requiring laboratory confirmation of new cases when labs were becoming overwhelmed.

Nearly 2 million Americans could be hospitalized during this winter's novel H1N1 influenza pandemic, with as many as 300,000 clogging intensive care units in heavily affected regions, according to a report released Monday by the President's Council of Advisors on Science and Technology. Overall, 20% to 40% of the population could develop symptoms of the strain commonly known as swine flu, and 30,000 to 90,000 could die, according to the report. During a normal flu season, the virus kills about 35,000 Americans.

Anna Manzanarez was a picture of good health. But about a week after catching what she thought was a bad case of the flu, the 28-year-old waitress from the central California coastal community of Seaside collapsed getting out of the shower. The next day, despite intensive care at a hospital, she died.

Responding to concerns about antibiotic-resistant "superbug" staph infections, California will now require local health departments to report all severe infections originating outside healthcare facilities, but not cases contracted in hospitals or nursing homes.

A dangerous form of drug-resistant tuberculosis has reached its highest levels ever, accounting for at least 5% of all new TB cases worldwide and 15% to 22% of new cases in parts of the former Soviet Union and China, the World Health Organization said Tuesday. The WHO report, the first new survey of TB incidence in four years, estimates that there are nearly 500,000 new cases of multidrug-resistant TB, commonly known as MDR TB -- about 5% of the 9 million total new cases of TB each year.

A preschool-age child in Los Angeles County has been hospitalized with measles, and public health officials Monday urged parents and physicians to be on alert for the highly contagious disease. It is the first case reported in the county since 2006. The child had not been vaccinated against measles, said Dr. Jonathan Fielding, the county's public health director. The virus is spread by sneezing and coughing. Symptoms include a rash, coughing, a runny nose and red, watery eyes.

Brazil is booming. The currency is soaring, people are buying houses and cars at a record pace, and global financiers are keen to invest. The country seems poised to acquire official First World status. But residents of this self-proclaimed city of wonders are worried and angry about a Third World affliction -- dengue fever, the tropical disease spreading in epidemic fashion here.

Chinese authorities have ordered local health officials to swiftly report all new cases of a fast-moving virus blamed for killing 28 children across the nation and infecting more than 15,000, most younger than 5. Cases of Enterovirus-71, a strain of what is often called hand, foot and mouth disease, must be reported to the Health Ministry within 24 hours of detection, officials announced Wednesday.

Despite plummeting mortality rates for most infectious diseases over the last century, a group of largely overlooked bacterial, viral and parasitic infections is still plaguing the nation's poor, according to a report released this week. Many of the diseases are typically associated with tropical developing countries but are surprisingly common in poor regions of the United States, according to the analysis, published in the Public Library of Science journal PLoS Neglected Tropical Diseases.

The flu may be getting a late start this year, but we haven't escaped virus-induced misery. Noroviruses, which cause gastrointestinal illness, appear to be more widespread and severe than usual this winter, federal health officials say. For those who've succumbed, no explanation is necessary. Those who haven't are lucky. Noroviruses -- actually a group of about 40 strains of virus -- cause intense vomiting, diarrhea, abdominal cramps, headache and fever.