viroLOGICAL

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.

This time it's a herpes virus that almost all of us carry: human cytomegalovirus (CMV). Florian Krammer explains why this large DNA virus with over 200 proteins is so hard to pin down, how it deposits its genome as an episome inside immune cells and stays hidden there for decades.

This time it's a virus that has circulated in humans for millennia: mumps virus. Florian Krammer explains why this paramyxovirus is related to measles and the dangerous Nipah virus, how the infection unfolds, and why it's usually mild but can cause serious complications including inflammation of the testicles, brain, or pancreas.

A summer update with four current stories from the world of virology. First stop is Switzerland, where thousands of cows fell ill from a newly discovered orthobunyavirus of the Simbu group, closely related to Schmallenberg virus but with little risk to humans.

The final part of the summer series on vacation viruses is one you can catch without going anywhere: West Nile virus. Florian Krammer explains why this flavivirus is closely related to Japanese and St. Louis encephalitis virus, how it mysteriously showed up in New York in 1999 - most likely via mosquitoes on a container ship and spread across the entire US within a few years.

Part three of the summer series on viruses you can pick up on vacation. After Italy and Scandinavia, it's off to the tropics. Oropouche virus causes Oropouche fever and is spread not by mosquitoes but mainly by tiny midges — the same bloodsuckers that transmit bluetongue disease.

Part two of the summer series on viruses you might pick up on vacation — this time heading north. Sindbis virus is transmitted by ordinary Culex mosquitoes and causes a disease known variously as Pogosta disease, Ockelbo disease, or Karelian fever. Florian Krammer explains why it's closely related to chikungunya (you could call it the chikungunya of the north), how migratory birds spread it across Eurasia and Africa, and why most infections go unnoticed — there are 20 to 40 asymptomatic cases for every symptomatic one.

The first of a short series on viruses you might encounter while travelling: Pappataci fever is transmitted by sandflies and caused by viruses like Toscana virus, Naples virus, and Sicilian sandfly fever virus. Florian Krammer explains where the Italian name comes from, why these tiny 3-millimetre flies are poor fliers and therefore stay close to the ground, and why up to 25% of people in affected regions carry antibodies without ever having felt sick. Most infections are mild, but Toscana virus is neurotropic and can, in rare cases, cause meningitis or encephalitis. There's no vaccine and no treatment — insect repellent and long trousers are your only defence.

In this episode of viroLOGICAL, Florian Krammer explains the Marburg virus, a filovirus closely related to Ebola that causes severe hemorrhagic fever. He discusses how the virus is structured, how it enters cells, how it is transmitted from animals and between humans, and why infection is associated with very high mortality.

This time it's not about a virus, but about one of the most exciting developments in modern medicine: therapeutic cancer vaccines based on mRNA. Florian Krammer explains the basic principle — how a patient's tumor is sequenced, how the mutated genes (so-called neoantigens) are turned into a personalized vaccine, and how that vaccine trains the immune system to recognize and destroy cancer cells.

A new tick-borne virus has just been detected in Austria for the first time and antibodies found in two people suggest it can infect humans here too. Florian Krammer explains what makes the Alongshan virus so unusual: it belongs to the Jingmen viruses, a group of segmented flaviviruses that are built almost like a hybrid between a flavivirus and an influenza virus.

The second part of the HIV series covers everything that happened after the virus was discovered: the intense stigma of the early years, the US government's years of inaction under Reagan and the activism that drove the development of treatments and public awareness. Florian Krammer explains how a near-certain death sentence became a manageable chronic condition, what PrEP is and how it works, and how a handful of people (the "Berlin patients") were actually cured of HIV. The episode closes with the current situation: why UNAIDS estimates that the withdrawal of US funding could lead to millions of additional infections and deaths worldwide.

The first of a two-part series on HIV starts with the virus itself and its history. Florian Krammer explains why HIV is one of the most cunning viruses we know: it infects the very cells of the immune system, permanently writes itself into our DNA, and hides from immune detection.

To wrap up the hepatitis series, this episode covers the final letter: hepatitis E. A virus that's harmless for most people, often going completely unnoticed, but can be life-threatening for pregnant women and those with weakened immune systems.

An Ebola outbreak is currently unfolding in the Democratic Republic of Congo — caused not by the well-known Ebola Zaire, but by Bundibugyo Ebola virus, a species for which no licensed vaccines or proven treatments exist. This episode covers the basics of Ebola viruses, how they spread, why they cause such severe disease, and what makes this particular outbreak so difficult to contain: it was detected late, it's happening in an active conflict zone, US support has largely been withdrawn, and the medical countermeasures simply aren't there yet. A global pandemic is unlikely given the transmission routes, but for the local population, this is already a serious tragedy.

We all inhale mold spores every day — for most people, that's not a problem. But for those with a weakened immune system or pre-existing lung conditions, it can become life-threatening. In this episode, Florian talks with Prof. Helmut Salzer, Head of Infectious Diseases and Tropical Medicine at Kepler University Hospital in Linz, about Aspergillus and the three forms of aspergillosis: invasive, chronic, and allergic. Around four million people are affected worldwide every year, with more deaths than influenza causes annually. Yet the disease remains largely under the radar.

Andes virus is the only known hantavirus that can spread from person to person and that's exactly what makes the current outbreak on the cruise ship MV Hondius so unprecedented.

Before SARS-CoV-2, there was SARS-CoV-1 - a closely related coronavirus that caused a serious outbreak in 2002–2003 with a case fatality rate of around 10%. Unlike its successor, SARS-CoV-1 only became transmissible after symptoms appeared, which made it possible to identify and isolate infected people even without PCR tests. The virus spread from China to Hong Kong, Canada, Singapore, and Vietnam via superspreader events before a global effort managed to contain it by June 2003. The likely origin: horseshoe bats at wet markets in Guangdong, with palm civets and raccoon dogs as intermediate hosts.