Tag Archives: Humans

Black death: Plague was spread by people, not rats, and controlled by basic sanitation

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Between 1340 and 1400, the Black Death spread throughout Europe, killing more than 20 million people. For hundreds of years, it was thought that fleas carried by black rats spread the deadly disease. But new research suggests that the “vermin” might not be to blame.

Kristin Hugo of Newsweek reports a study published in the Proceedings of the National Academy of Sciences on Monday illustrates how the plague might have spread. Researchers at the University of Oslo ran computerized mathematical simulations of disease spread by human-to-human fleas and lice, by human-to-rat-to-human fleas, and by airborne pathogens.

The researchers compared those computerized simulations to nine examples of the actual spread of the Black Death. They found that the simulations of human-to-human models most closely resembled the actual spread patterns in the nine real studies that they investigated, indicating that rats might not have been involved at all.

A study published in 2011 supports this conclusion. Authors say that the spread of the plague was too fast for rats to have been an intermediary, and furthermore, researchers should have found more dead rats that had succumbed if they were such important disease-carriers.

Another study in 2015 criticized the idea of rats as reservoirs of disease, claiming that the weather was too cold and rainy for rats to thrive and spread the disease widely. And an ecological review in 1986 cited a general lack of evidence for rats as the carriers of the disease.

However, exonerating the rats is likely to prove controversial among historians, who believe that the bacteria must have at least come from rats, or some other animal carrying fleas, at some point. The researchers at Oslo admit that their computer simulations could use more data, according to National Geographic. The more data a program has, the more accurate simulations it can run. 

Notably, the Black Death lost its grip when people started improving sanitation and cleaning themselves regularly, and covering sewers.

Can humans get Norovirus from their dogs?

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Human norovirus may infect our canine companions, according to research published online April 1 in the Journal of Clinical Microbiology, a publication of the American Society for Microbiology.

sadie.dog.powellThat raises the possibility of dog-to-human transmission, said first author Sarah Caddy, VetMB, PhD, MRCVS, a veterinarian and PhD student at the University of Cambridge, and Imperial College, London, UK. Norovirus is the leading cause of food-borne illness in the United States, according to the Centers for Disease Control and Prevention (CDC).

The research showed that some dogs can mount an immune response to human norovirus, said Caddy, who will be a junior research fellow at the University of Cambridge, beginning in August. “This strongly suggests that these dogs have been infected with the virus. We also confirmed that that human norovirus can bind to the cells of the canine gut, which is the first step required for infection of cells.”

Caddy and collaborators performed the latter research using non-infectious human norovirus particles, which consist solely of the virus’ outer protein, called the capsid. The capsid is the part of the virus that binds to host cells. By itself, it is non-infectious because it lacks genetic material. (The non-infectious capsid is the basis for a new norovirus vaccine which is being tested in clinical trials, said Caddy).

Nonetheless, it is not clear just how much of a problem canine infection and transmission may represent for humans, said Caddy. Despite dogs’ apparent susceptibility, the investigators failed to find norovirus in canine stool samples, including those from dogs with diarrhea. They found it in serum samples of only about one seventh of 325 dogs tested.

Additionally, it is not yet known whether human norovirus can cause clinical disease in dogs Assuming that dogs become infected with human norovirus as per this study, it also remains unknown whether they could shed the virus in quantities sufficient to infect humans—although clinical investigators have estimated that as few as 18 virus particles can cause human infection.

Moreover, it is yet to be determined whether dogs play a role in the epidemiology of some outbreaks of human norovirus. Some of the biggest outbreaks occur in places from which dogs are absent, such as on cruise ships and in hospitals.

Humanure: It’s extreme, like Mountain Dew, if it was derived from human poop

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For more than a decade, 57-year-old roofer and writer Joseph Jenkins has been advocating that we flush our toilets down the drain and put a bucket in the bathroom instead.

When a bucket in one of his five bathrooms is full, he empties it in the compost pile in his backyard in rural Pennsylvania. Eventually he takes the resulting soil and spreads it over his vegetable garden as fertilizer.

"It’s an alternative sanitation system," says Jenkins, "where there is no waste." His 255-page Humanure Handbook: A Guide to Composting Human Manure is in its third edition and has been translated into five languages, but it has only recently begun to catch on. His message? Human manure, when properly managed, is odorless. His audience? Ecologically committed city dwellers who are looking to do more for the earth than just sort their trash or ride a bike to work.

Night soil is rumored to be used in the production  of fresh veggies , especially for upscale restaurants, in many large cities.

I’ll stick with riding my bike to work, and thank engineers for sewage treatment.
 

Salmonella in people from dry dog food

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Health types have traced several Salmonella outbreaks to various pet treats like pig ears and other chewies over the years.

Now, dry dog food has been linked to a Salmonella outbreak in humans.

From January 1, 2006–December 31, 2007, the U.S. Centers for Disease Control and Prevention and others investigated a total of 70 cases of Salmonella enterica serotype Schwarzengrund infection in humans in 19 states, mostly in the northeastern United States.

The source of the infection was dry dog food produced at a manufacturing plant in Pennsylvania, the first time contaminated dry dog food has been identified as a source of human Salmonella infections. CDC recommends that after handling pet foods, pet owners should wash their hands immediately, and infants should be kept away from pet feeding areas.