viroLOGICAL

For Halloween, this episode is about one of the scariest viruses around, at least if you’re an insect: the baculovirus. Florian Krammer explains how these large DNA viruses infect the caterpillars of moths and butterflies, change their behavior so they climb to the top of the plant, and then liquefy them so the virus spreads as widely as possible.

Shamonda virus is a bunyavirus of the Simbu serogroup, closely related to Schmallenberg, Akabane and Oropouche virus. It was first identified in 1965 in Ibadan, Nigeria, and is known to infect cattle, sheep and goats, transmitted by biting midges.

With the respiratory virus season starting, Florian Krammer gives an overview of what’s circulating and how to protect yourself. He explains why respiratory viruses spread more easily in the cold and how influenza plays ping pong between the northern and southern hemispheres.

Lymphocytic choriomeningitis virus (LCMV) is an arenavirus closely related to Lassa virus, but unlike Junin virus it isn’t limited to South America: it’s found worldwide in house mice. Florian Krammer explains how people get infected, mostly by inhaling dust from dried mouse urine, droppings or saliva, and less often through bites, contaminated food or infected pets like hamsters.

Since the 1970s, cats in Sweden, and later in and around Vienna, have been falling ill with a mysterious brain inflammation known as staggering disease. Affected cats develop fever, behavioral changes, a staggering gait and often paralysis of the hind legs, and most have to be euthanized. For decades Borna disease virus was the main suspect, but metagenomics finally solved the case: in 2023, rustrela virus, a close relative of rubella virus, was detected in 27 out of 29 affected cats from Sweden, Germany and Austria.

Junin virus causes Argentine hemorrhagic fever, a disease with a case fatality rate of 20 to 30 percent. Florian Krammer explains why these New World arenaviruses are named after sand (they package host cell ribosomes that look like grains of sand under the electron microscope) and what makes their spike protein unusual: the signal peptide stays part of the glycoprotein complex, something found nowhere else in biology. The virus is carried by field mice, mainly the dryland vesper mouse, and people usually get infected by inhaling dust from dried urine and feces. That's why it mostly affects men working in agriculture, with over 90 percent of the 300 to 500 annual cases occurring in rural areas.

Human metapneumovirus (HMPV) is one of the most common respiratory viruses there is, yet few people have heard of it. Florian Krammer explains why this relative of RSV is the second most common cause of respiratory illness in children under five and is behind 8 to 15 percent of pneumonia cases in that age group.

The 1918 Spanish flu was the deadliest influenza pandemic on record: between 20 and 100 million people died, from a world population of just 1.8 billion at the time. Florian Krammer explains why this H1N1 virus, with a case fatality rate of two to three percent, was so dangerous, where the misleading name comes from (Spain was neutral and had a free press when warring countries did not) and why mortality peaked among 20 to 40 year olds in a distinctive W-shaped curve.

Canine distemper virus is a paramyxovirus and a close relative of measles virus. Florian Krammer explains why the disease is so dangerous for unvaccinated dogs: in puppies between three and six months the case fatality rate is around 80 percent, and roughly 50 percent in adult dogs with no immunity.

Recorded in Sapporo, this episode is about a virus causing severe disease across Asia: SFTS virus, officially named Dabie bandavirus. It spreads mainly through the Asian longhorned tick, and in rare cases directly between people via blood and bodily fluids.