When I attended the University of Arizona I took an excellent course taught by Albert Mead called Parasitology. We used a text book called "Manual of Tropical Medicine" by Hunter, Frye, and Swartzwelder, and were fortunate in that Dr. Mead had an excellent collection of microscope slides from his work in Africa. We got to see all four then known species of Plasmodium (malarial parasites) known to infect humans, plus a host of parasitic amoebae, flagellates, and worms. It was so fascinating that I followed it up with courses on Medical Entomology and Mosquitoes at the University of Florida. However I was warned against altering my career by a researcher at a laboratory in south Florida. He said that there was just too many epidemiologists for the job opportunities. However, I really got to appreciate the need to understand tropical parasites and diseases in this age of rapid transport from distant lands, and to believe that every hospital and clinic should have at least a few doctors with training in these fields. This was driven home recently by the appearance of ebola at a Dallas ER and the bungling of the disease identification and treatment of the patient.
I grew up when mumps, measles, chicken pox, diphtheria, scarlet fever and whooping cough periodically swept through the community, as well as polio. We also had several years when rabies went through the dog, coyote, fox and skunk populations and every stray dog was suspect. I contracted measles and chicken pox in childhood, followed by mumps as an adult, as well as flu periodically. I later had shingles as a result of the latent chicken pox virus. My father's first wife died of tuberculosis and my grandmother's first husband died of rabies after he refused the Pasteur treatments. Our Methodist minister's wife died of polio. My wife had at least three and probably more uncles and aunts die of childhood diseases. Both my wife and I were vaccinated for small pox. My wife's father had hepatitis (probably type A) and may have had malaria, and one of my associates at the university had dengue. Thus I have both first and second hand experience with the period pre-vaccination (except for small pox and later polio) and with other diseases that lack vaccinations to the present day. It was not so wonderful in the 1950s, when epidemics swept through communities regularly.
Epidemic disease has always been with us and at one point that we know of, the Black Death of the mid-1300s, such a disease actually lowered the earth's population for a while. The 1918 flu may have killed more people, but the human species was breeding so fast at that point that it did not significantly alter the steady and ever steeper rise in human numbers. However, despite all our medical technology about a million or so people die each year from malaria alone and tropical epidemic diseases like ebola are certain to emerge and spread. We are just lucky that at this point ebola is not air-borne!
When I visited the American tropics 15 years ago I had no doubts - I was vaccinated for everything recommended by the CDC. It was worth it! One of our daughters added a rabies vaccination to that when she went to Africa to study the vectors of two arboviruses, dengue and chikungunya, before they hit the U.S. ChikV (as they call it) is now in Florida and dengue is probably not far behind. We have the vectors in place in the southern tier of states. Tonight when I leave my front door I know that I will be followed by a small cloud of one of these, Aedes aegypti, the yellow fever mosquito.
Aedes aegypti on my blue jeans in 2002.
Fortunately these mosquitoes do not transmit West Nile virus, which is established in the populations of several species of Culex, and we have so far avoided dengue, yellow-fever and ChikV. It helps to know your vectors - not all mosquitoes are equal. The yellow fever mosquito (only one individual) was first collected in traps in 2000 in Mesilla Park, New Mexico. Prior to that we did not have it! The Asian tiger mosquito, Aedes albopictus another vector of dengue and ChikV, is expected shortly. I have the odd distinction of being the first person recorded to have been attacked by yellow fever mosquitoes in southern New Mexico!
For a short time I was involved in a study on the vectors of West Nile virus, mainly in the writing of a grant proposal. However, my career had already diverged into biocontrol of pest insects and weeds, so I did not continue (we did get the grant!). While a threat, West Nile is not a major cause of death (although it can devastate some bird populations, especially corvids). It is one of many emergent and potentially emergent diseases with which we will have to deal as environments change and global warming continues. The huge population of humans is certainly a factor, though by no means the only one. Concentrations of populations in slums and barrios around the world are time bombs, waiting to go off, just as the slums in medieval cities proved to be wonderful incubators for the Black Death. If they do, like has already happened with ebola in West Africa, they will eventually swamp our health care system as it now stands. Cutting money from the CDC, the WHO, and the NIH, is not a good idea (see: http://www.motherjones.com/....) I well know that there is waste and sometimes corruption in these organizations, however the majority of people involved in health care and research are honest and hard working. We have been fools not to give them the resources that they need.
In essence the increase of humans to over 10 billion, as recently predicted, will present disease organisms, both well-known like pertussis and emergent like ebola, with great opportunities for expansion. Global warming will also expand the range of vectors. Multiply medieval slums by a factor of 30 or more in a warming world and you can see the problem. Unless we alter this, humans will find their civilization overwhelmed by famine, war, pestilence and death, as it was for a time in the 14th Century. We may already be seeing the future in ISIL and ebola.
On this note I am thinking of ending my diaries with this, my 101st diary. People who have read them have probably gathered whatever wisdom or knowledge, if any, that I can impart. The Buddha is said to have remarked that “But those who grasped after marks and philosophical views, they wander about in the world annoying people.” I would avoid this by ceasing further commentary, and by not repeating myself, as I most certainly may do. If I have annoyed anyone, I hope not too seriously. I have, however, enjoyed this opportunity to clarify my own thoughts and to learn from others comments, which I assuredly have done. Thank you all!!