Another Week, Another Virus – Hantavirus in Yosemite

Another virus made the news this week, but it seems isolated enough, more so than the West Nile Virus featured last week that covered most of the country.  This one is isolated in one campground at the Yosemite National Forest in East-Central California.

It’s made news because it fits the standard of an isolated outbreak: 2 confirmed deaths, 1 more confirmed case, and 1 probable case as of earlier this week. = 4 cases this year. This compares to just 1 case in 2000 and 1 more in 2010.

What is it?

Hantavirus Pulmonary Syndrome (HPS) is caused by a spherical virus spread through mice and rodent urine and droppings. You breathe the virus in. Hantavirus is actually a genus of viruses which have such specific common names as “Sin Nombre virus” and “Hantaan virus.”

These viruses are spherical and have 3 strands of single-stranded RNA – not DNA.

The rats and mice are carriers, but they don’t seem to get the disease. And the virus spreads through their droppings.

What happens in the body?

They say the diagnosis is difficult, because it’s vague and often confused with the flu. The early symptoms are fever, muscle aches and fatigue. Don’t tell me you’ve never had these symptoms.

The main effect is in the blood vessels: increased permeability and decreased blood pressure. The capillary opens up between the squamous epithelial cells and allows more fluid to drain out of the blood. That floods areas like the lungs’ alveoli. And because liquid is leaving the tubes we call blood vessels, and spreading out, the blood pressure drops. Imagine trying to blow bubbles through a straw with holes in it. It’s harder than normal to push through to the water to blow the bubbles.

Symptoms show up around 2-3 weeks after exposure – the “Incubation time” of the virus is 2-4 weeks.

Late symptoms have to do with the lungs: shortness of breath, difficulty breathing and coughing. By this time, you’d want to go to the hospital. There is no treatment specific to the virus that I’ve seen, but the patients will be given oxygen to start, to help increase oxygen in the blood (what the medical people call O-2 Saturation). Looks like they treat the patients signs and symptoms and let the virus run its course and leave the body? Almost sounds like treating the common cold virus.

The illness can cause death from lung failure. Lung fills with fluid from this increased vessel permeability, and you lose the ability to exchange gases in the alveoli because you have fluid on both sides of the endothelium lining.

Prevention of Spread!

Three words: Keep Mice Away. Keep clean! No food scraps or crumbs that will attract mice! The National Park Service cleaned the campground thoroughly earlier this month, and they are no longer warning people who are staying there after that cleaning.

The virus does NOT spread from person to person.



Like last week, if you’re interested in this field, be sure you take microbiology and look for careers in the Public Health Sector: local and state governments’ public health departments, Vector Control Districts, the Centers for Disease Control (CDC) in Atlanta, and the U.S. Public Health Service (did you know this last one has a “Commissioned Corps” that is a U.S. Uniformed Service, just like the Army, Air Force, Navy, and Marines?)


If there’s nothing new this coming week in health news, I’ll highlight some of the most deadly viruses they’re studying at the CDC in Atlanta next week.





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