Richard Knox

A lot of medicine's direst emergencies come down to one problem: lack of oxygen.

Cardiologist John Kheir started thinking about that when a little girl in his care, drowning from lung hemorrhages, died before she could be hooked up to a heart-lung machine that would have kept her blood oxygenated while the damage was repaired.

The Ebola virus continues to strike people in the Democratic Republic of Congo. Since May, the World Health Organization has counted 72 confirmed, probable or suspected cases and 32 deaths.

As usual, a disproportionate share of those cases are health care workers — 23 of them, almost a third.

The numbers for West Nile virus cases continue to rise, up 35 percent in the last week. But the Centers for Disease Control and Prevention is confident the nation has turned the corner on its worst-ever epidemic of West Nile virus disease.

Flu pandemics don't happen very often. So many people might feel the relative fizzle of a flu pandemic three years ago somehow immunizes the globe against another one for awhile.

But don't relax, say the authors of a report published online in the Proceedings of the National Academy of Sciences.

Cholera vaccine gives indirect protection to unvaccinated people in communities where a substantial fraction of the population gets the vaccine, a study in Africa shows.

The effect is called "herd immunity." It works because there are fewer bacteria circulating in communities where vaccination levels are relatively high.

Seventeen states offer tax incentives to people who donate a kidney, a portion of their liver or bone marrow for transplantation. But a study finds these sweeteners aren't working.

Researchers looked at what happened in the years before and after these tax incentives were passed and found no increase in organ donation rates.

Two Missouri farmers have been infected with a brand-new tick-borne virus that the Centers for Disease Control and Prevention is calling the Heartland virus.

The men recovered but suffered serious illness that required hospital care and weeks of convalescence. Symptoms included fever, severe fatigue, headache and nausea. Their platelet counts plummeted, but even though platelets are necessary for blood clotting, the men didn't suffer abnormal bleeding.

This year is on track to be the worst ever for West Nile virus in the United States. Here are the latest numbers from the Centers for Disease Control and Prevention:

• 1,590 reported cases, nearly 500 more than a week ago for a rise of 44 percent.
• 889 cases, or 56 percent, involve severe neurological disease.
• 66 deaths, compared to 41 last week.

Flu is most deadly for children with neurologic problems and disorders, an analysis of swine flu fatalities finds.

The results come from Centers for Disease Control and Prevention researchers who looked at childhood fatalities during the H1N1 flu pandemic of 2009, when there were five times the usual number of deaths.

In all, 43 percent of the deaths occurred in children who had neurologic diseases, such as cerebral palsy and epilepsy, or developmental disorders.