For single-celled creatures to traverse the world at first seemed impossible. Having no legs, locomotion on more than a microscopic scale presented unimaginable obstacles. However, with the assistance of two faithful servants, humans and sand flies, we have been able to circumnavigate the globe. Here, your intrepid Leishmania reporters endeavor to recount the sights and sounds of our travels.

We began our travels under our own steam. Nimbly transforming to move between the warm blood stream of mammals and the cold bodies of sand flies. It has required some ingenuity on our part, but we found that the mammalian white blood cell made a fine and cosy carriage for the first part of our journey.

Who would have thought that those who at first seemed to be our enemies, intent on our absorption and destruction, could be persuaded to ignore our alien status and even to assist us in our travels throughout the body!

To travel by sand fly is to travel by a somewhat unreliable method. Following the example of the local inhabitants we merely wait for one to turn up in our vicinity. Thankfully, this occurs with a high frequency, but one never knows quite when to expect them, and so we must be constantly prepared to disembark with alacrity. Instead of a boarding bridge we use a rather narrow corridor to enter the first reception area of the sand fly. Quite incredible that we should pass through its head, and then to be sluiced through and into the opulent surroundings of the gut. Unfolding that most exquisite invention the ‘flagella’ to swim, we adapted to the new circumstances.

We have become quite nicely accustomed to our new environment. We hope it is not too indelicate to mention that we have spent our time here reproducing! Not in a conventional way but through a process of dividing, so that one of us becomes two, two become four, and so on. We simply find this more convenient, and are never surprised by wayward offspring, they’re always a chip off the old block!

Soon, however, we became a crowd, pushing and shoving at the entrance to get out again. In the crush we’re afraid the door became somewhat damaged, so when the sand fly stopped to pick up more passengers we slipped through and out into another warm mammalian body. Our friends the white blood cells were there to greet us, and soon we were able to put aside our flagella and settle back in.

For millions of years we enjoyed traveling incognito, known only through evidence made apparent in our hosts. We are somewhat at their mercy, and time and again we are left stranded by their incompetence. Imagine how we felt as the sand fly that was transporting us became carelessly stuck to some tree resin. All we could do was sit helplessly as we all became engulfed by that fragrant oozing yellow wave. Millennia later they have the effrontery to be the marvel of all inside their amber gemstone tombs, while we are sitting still, hidden inside and receiving none of the glory! You would think the sand fly would learn from their mistakes, but it happened in Burma, the Baltic, Jordan, Mexico, Peru and the Dominican Republic. If you are ever to travel to those regions, we bid you to beware!

Sand flies and reptiles have been convenient vehicles as they spread around the world. We remember when we all used to live in Pangea, in much simpler times before we found our mammalian hosts. The travel was, quite frankly, very limited in comparison to today. We like to pride ourselves that we were already seasoned travelers by sand fly, and when the continents drifted apart we were able to take advantage of the seismic shift in travel opportunities. Although I haven’t been able to take tea with my cousins on other continents for a lamentably long time, it is good to know that we survived such earth shattering times and have prospered in many disparate locations.

The group residing in the liver were the first to notice that something was amiss when it was violently wrenched from its place in the body and placed in a jar. Those of us still in the veins were left to slowly dry out, parched for more than 70 days! It was more than we could bear and we were unable to witness the ceremony of being wrapped in bandages and preserved. We were however thoroughly delighted to hear that this time we didn’t go un-noticed, and have since been discovered in mummies in Egypt and Peru, only 3,000 years later.

There are several sides to our family, most notable are those of us that seek out the internal organs, and those that inhabit the skin. In Ecuador and Peru we were most notorious for traveling in the latter from as early as 100 A.D.  We must remark on how delightful the Chicama Valley in Peru was as a destination, with its irrigation systems, monumental architecture, gold work and beautifully painted ceramics. The local Moche people were so hospitable that they fashioned a ‘whistling vessel’ to commemorate our presence.

So much for traveling incognito, our reputation is beginning to travel before us. We were delighted that news of our effects has received a royal mention! King Ashurbanipal of Assyria, Babylonia and Egypt wrote about the human symptoms of our presence on his famous tablets of 700 B.C.

Throughout the world we have benefited from the voyages of men and women over local and international boundaries. We are however particularly indebted to the Spanish and Portuguese conquistadores for their generous offer of transcontinental travel in the 16^th Century. Although we often travel in humans and sand flies we are also partial to voyages with other mammals, and dogs are one of our favourites. We got more than we bargained for when we boarded ‘Becerrillo’. Unbeknown to us, he was Poncé de Leon’s dog and took us to lands we had not previously explored.

Trained as a dog of war he had a taste for human flesh in a more savage way than we do. He was involved in some extremely unsavoury behaviour. Our deadly work is undertaken slowly and invisibly from the inside, Becerrillo and his friends were a vicious, obvious, and immediate threat. The conquistadores, their dogs, and ourselves made a deadly and unrelenting team, laying waste to native populations.

We call the dog our ‘reservoir’, a place to gather and socialise between humans and sand flies. We were rather worried about whether we would find onward travel options in a new continent, but we should not have been so troubled. The South American sand fly was a more than adequate flight service, and accommodated all our travel needs, delivering us safely to human hosts. While we were there we met some of our local relatives that had been commemorated in the whistling jugs. We must say that their preference for residing in the skin is most cordial, and leaves their hosts alive and active. In comparison they must find our way of inhabiting the internal organs quite brutal.

During our time in Syria in the mid 18^th century our skin-living cousins met with a physician named Alexander Russell, who called our effects the ‘Aleppo Boil’. We are of the opinion that encouraging this kind of publicity is dangerous, and can cause deleterious delays to our travel plans as it encourages those human scientists to find ways to prevent our forays into new territory. However this wasn’t to happen for a number of years.