Some old fuds think magic pills can keep their minds from ossifying. I take mini-courses my local university offers. The latest concerned communicable diseases and was taught by a microbiologist, Janne Cannon. She was excellent and the course alarming.

After a brisk canter thought plagues and epidemics including the Black Death, the 1918 Flu pandemic, polio, guinea worm, smallpox, malaria and their hundreds of millions of deaths, we concluded with a look at what the future holds. More of the same, of course.

If nothing else, such an exercise reminds us that man does not live by dread of Trump alone. Worse is awaiting in the wings. So, what can science suggest about the shape of the next pandemic to come? As is customary in cases like this, Prof. Cannon is responsible for the facts that follow. I take the blame for any errors or opinions.

First, it will likely be a zoonosis. That, we learned, is a disease of animals that becomes transmittable to humans. According to the CDC, six of ten known infectious diseases originated in this way and three out of every four emerging diseases are zoonoses.

It is also the case that pathogens that infect multiple animal species are more likely to make the leap to humans — a so-called spillover. And lest we think that such a thing is highly unlikely, researchers estimate the number of unidentified diseases already lurking in animals that have a spillover potential is somewhere between 634,000 and 827,000. It will only take one.

Second, the next pandemic is more likely to be caused by a virus than by a bacteria, fungi or parasite for the simple reason that it is far harder to develop successful treatments for viruses. This has to do with the structure of viruses and the fact that they make us their host, invading our cells and hijacking them to make more copies of themselves.

Attacks on them must, therefore, be oblique. A frontal assault to kill viruses that entails killing the cells that host them also risks killing the creature of which they are a part — that is, us.

Third, the outbreak of the next pandemic is likely to gain a foothold in disorderly regions where humans are vulnerable due to war, dislocations, poverty, malnutrition, chronic diseases, polluted water, unsafe food, and inadequate healthcare facilities and infrastructure making a disease surveillance regimen difficult. Once established in a human population in such a place, the spread can be rapid.

Fourth, experts worry about several animal species in particular as possible threats. Avian populations are often carriers of disease, notably influenza. In many cultures, fowl raised for food are a worry due to their close proximity to humans. Migratory birds have the capacity to spread a disease more widely.

Another worry is bats, known to harbor Ebola, Hendra, and Marburg viruses. A peculiarity of their immune systems apparently protects bats from such viruses while still allowing them to spread their deadly cargo to other species, like us.

Finally, the course a likely pandemic will take can be anticipated. A virus in bats, birds, or non-human primates will mutate, possibly by the mingling of several strains in a reservoir population, into something new and dangerous to humans.

Viruses that reside in the liver, central nervous system or respiratory tract are more likely to be transmitted to humans and a class of viruses without a lipid coating is more likely be the culprit because it can remain infectious for longer in air, water, or on surfaces.

In stage one, a virus from a reservoir species like bats or monkeys will be transmitted to farm animals like cows, sheep or fowl. In stage two, it will leap from animal to human but will remain localized. In stage three, the disease will spread widely to become a pandemic. Once this might have taken years. In our time, air travel makes the possibility of rapid spread to global proportions far more likely.

If all of that isn’t enough to keep you up at night, climate change will make the dangers worse. The range of mosquitos that carry tropical diseases like malaria, dengue, West Nile and Zika is now expanding as average temperatures rise.

The same mosquito species that carries Dengue is now found as far north in America as the Carolinas and Virginia. Malaria which causes several hundred million people to become ill annually in the tropics is now creeping farther north in the Caribbean, Central America, and beyond.

Recently, 11,000 cases of Dengue Fever, usually associated with sweltering places like India and Bangladesh, have been reported in Nepal. It is only a matter of time until billionaires, chatting about the loss of their beach houses to rising seas, contract a tropical disease at the annual alpine meeting in Davos.

What is to be done? Vigilance, of course, is essential, especially in places likely to be the source of an outbreak. These include Egypt and much of Asia where fowl are kept in close proximity to people. Scientists are trying to get better at estimating which viruses are most likely to mutate or leap to humans.

Unfortunately, America’s Isolationist-in-Chief has acted to reduce funding for medical research and has decreed that study and research in foreign countries be defunded. Yet that is where the pandemic danger will originate and with luck could be isolated before the spread.

How risky is this kind of xenophobic game? Several waves of plague, especially those beginning in 542 AD and 1346 AD originated in the East and moved to Europe. Each lasted several hundred years and killed between a third and half of the population.

Smallpox has been identified as early as 1,100 BC. Before a treatment was discovered, it killed a third of all those infected. As late as the eighteenth century it still killed, crippled, disfigured or blinded 10% of the population of Europe.

The so-called Spanish Flu of 1918 is believed to have sickened one billion people around the world and to have killed 50 million or more in a single year. An equally virulent virus today would infect five billion and kill 250 million.

Perhaps we should be doing more, not less, to detect, isolate, and stop the next pandemic before it can spread. But foresight is far less prevalent in humans that emerging diseases in nature.