Background infectious diseases: a world even more teeming with helminths

Imagine that you are a worm watching this great human drama. You, like everyone else, just want to live and procreate. This means that you need to gain a foothold in the body of a host, Mature, lay fertilized eggs and, as far as possible, increase the likelihood that these eggs will find their way to a new host. As a parasite adapted to humans, about 70,000 years ago you would have cursed yourself for choosing this hominid as your host. During this period, for some mysterious reason (maybe it was a major volcanic eruption in Indonesia or climate change) Homo sapiens almost completely extinct. Judging by the loss of genetic diversity that occurred around that time, the human population had dwindled to only two thousand individuals. The humans seemed doomed, as were the parasites. However, after the threat of complete disappearance of our dependants almost certainly had something to rejoice.

At the end of the Paleolithic era, we spread all over the world and spread our parasites to every continent except Antarctica. And then, in the Neolithic era, we went into farming and ranching. For organisms dependent on their hosts, which, as expected, faced with the problem of recycling their own waste, this change in lifestyle was the greatest boon.

All data point to the intensification of helminth infestation in the Neolithic era. First, farming and irrigation in the tropics and subtropics created a new habitat not only for mosquitoes but also for skin-penetrating schistosomes. In fact, paleoparasitology appeared in the early twentieth century with the discovery and rehydration of schistosome eggs extracted from the preserved bladders of Egyptian mummies, whose age was 3200 years. Chinese mummies of the same period also became a refuge for these parasites.

The main symptom of schistosomiasis (urine with blood) greatly disturbed the inhabitants of Ancient Egypt [58]. The more temperate climate provided a brief respite. In 1991, a mummified Neolithic human body was found in a glacier located in the Alpine region along the border between Italy and Austria. Scientists named him ötzi named the nearby valley of Oetz. The man was 5,300 years old; along with an arrow lodged in ezie’s shoulder, a whipcord was found in his body.

Six thousand years ago, members of the lake communities of Switzerland and Germany had such a parasite as a fish tapeworm (“broad tapeworm”) [59]. And then after changing their diet, they got a cow tapeworm. In the Gallo-Romanesque and medieval period, tapeworms began to draw class distinctions [60]. Rich people, who clearly preferred undercooked fish and beef, had tapeworms more often than poor people. (In the twentieth century, the fish tapeworm earned a reputation as a helminth that prefers Jewish grandmothers. They were infected with this parasite when they tasted a delicacy-raw stuffed carp.)

By the early middle Ages, the combination of “Ascaris-trichuris” was ubiquitous in Europe, appearing in latrines across the continent. “It seems that the European historical period is inscribed on the parchment of Ascaris and trichuris,” notes parasitologist françoise Boucher.

In the Americas worms are also widespread, and long before the birth of agriculture. Chileans had tapeworms 6,100 years ago. The wide spread of hookworm in the pre-Columbian period was the reason that some have suggested an alternative migration path for the settlement of America. Why? Hookworm needs to spend some time in warm soil-that’s where fertilized embryos turn into larvae. According to this view, these parasites would not have survived the cold Beringian isthmus about 15,000 years ago. In all likelihood, some of the pioneers took a warmer route, or perhaps took a sea voyage that was shorter than the life span of these parasites. There is also a third possibility. Paleofarsalos from the University of Nebraska Karl Reinhard draws attention to the fact that people recreate the tropics by fire, dwellings, and clothing, wherever they settled. The macroclimate can be cold, but the microclimate we create is usually perfectly moist and warm.

Arriving in America, Europeans also brought their parasites there. The “whipworm — roundworm” Duo is present in colonial-era sediments in Williamsburg, Virginia, and Philadelphia. Norwegian immigrants (fish lovers) brought the fish tapeworm to Minneapolis. Residents of the five Points neighborhood in new York city (a notorious slum neighborhood in Lower Manhattan, around a pond that is now paved) had many whipcord and Ascaris. And Chinese workers brought in California such a exotic parasite, as liver Fluke, in the early nineteenth century.

The sediments accumulated in colonial Albany tell the story of an increase in parasitic load as the population grows. The Dutch West India company established the town as an Outpost for the fur trade in 1614, but by the mid-18th century it had become an important British military Outpost. The construction of barracks and Palisades began. The population increased. And judging by the amount of helminth eggs left in the sediments, the Albanians were sweltering in their own filth.

Cows and pigs roamed everywhere. Residents of the city poured the contents of chamber pots directly into the gutters or used it to fertilize the soil in the gardens. Scientists find clusters of parasite eggs located around houses and garden beds. In all likelihood, the inhabitants of the city constantly devoured invasive eggs along with vegetables. A teaspoon of soil from the cesspools of the time contained more than 150,000 parasite eggs. Prosperity did not help: parasites infected both rich and poor. And after the war of independence, the situation deteriorated further. The city’s population increased from 3,500 in 1790 to 50,000 in 1850, and then to 90,000 in 1880.

Hygiene improved for a while. At the beginning of the XIX century, the city was banned on the open discharge of sewage and there was such an innovation as cesspools, lined with stone. Both of these measures have reduced the spread of parasites. Then in the 1880s, the city’s sewer system was put in place (seemingly a real boon), but it discharged sewage directly into the Hudson river, which provided the city with drinking water. Now the people of Albany drank water from their own sewers.

The life of the city reflected other changes that were taking place at the time: the production of energy from fossil fuels, the abundance of consumer products, which led to the emergence of previously unimaginable amounts of waste, as well as the feverish growth of cities. The industrial revolution, which changed human life forever, was in full swing.

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