Posts Tagged With: Rabies

Could Bats be the Pharmacopoeia of the Future?

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This is some of the research that contributed to the recently released Darwin’s Paradox: An international science mysteryhttp://amzn.to/2k8qJgi. Bats have a major role in this books, also the people who try to protect them when they become a target of fearful people during the pandemic.

Could Bats be the Pharmacopoeia of the Future?

Bats have long been considered a threat to humans, but it might be time for that to change.

Of the almost 5,000 mammal species, about 20% are bats, chiroptera (KIE-ROP-TER-A) to be scientific. There are more bats species than any other order except rodents, and they inhabit every continent except Antarctica. Bats are everywhere, and they’re nocturnal, and they fly. What could be scarier than 1,000 species of bats flying into your nightmares?

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How about over 3,000 species of viruses? The International Committee of Taxonomy of Viruses has identified over 3,000 virus species. Unfortunately, a large number of the viruses that are dangerous to people spend their vacations with bats. The list of viruses that are hosted by bats is both long and scary: hepaciviruses, pegiviruses, influenza A virus, hantavirus, paramyxoviruses, and of course lyssaviruses which include rabies.

Besides the viral threat, bats are vampires, as every school child can tell you. NOT! Only 3% of the bat species are vampires, and those are isolated to south and central America.

Recall the major pandemics (Black Plague, Spanish Flu, HIV/AIDS)? All caused by viruses. People die from viruses. Bats host viruses. Bats and Rats … maybe we’d be better off if we killed them all?

This has been the myth, legend, and superstition for millennia. With modern science, it’s time to reconsider.

Science is now asking the question, “Why do viruses that infect and kill humans and other mammals exist benignly in bats?”

If scientists can answer this question, find what protects the bats, we might be able to prevent future pandemics and even cure the common cold.

Chiroptera differ from other mammals in several ways. First, bats reached their current evolutionary point over 33.5 million years ago, while other mammals continued to evolve. Felines didn’t even appear until about 25 million years ago, and people, homo sapiens sapiens, didn’t show up until a few hundred thousand years ago.

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This might explain why bats are better at dealing with viruses. Some scientists suggest that given 30 million years bats had time to evolve better defenses than we could in a few hundred thousand. Bats also had strong evolutionary pressures since they live in large, dense colonies – ideal for spreading viral infections. This is very different from primates which evolved in small isolated groups.

Others suggest that it’s just a numbers game. Given a thousand species of bats, to our one, they had a better chance to get lucky. This is supported by the rodents which have even more species and also host lots of viruses.

The third line of investigation is the high metabolism required for flight. This, combined with the observation that bats don’t seem to get cancer, leads to the hypothesis that their DNA repair mechanisms work faster and better.

This third hypothesis brings up another bat anomaly: not only are they more resistant to viral diseases, but they also live longer than expected. Are these two related? Maybe?

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Regardless, the denizens of Chiroptera have antiviral secrets that we need and science is working to find them. Today more scientists study the biology of bats, and more bats are getting their DNA sequenced. Perhaps soon we will live longer and healthier because of those scary, night flying, echolocating bats.

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Categories: Bats, Viruses | Tags: , , , , , , , , | 1 Comment

Thinking of Zebras #Rabies #Bats #Chiroptera #Medical

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This is some of the research that contributed to the recently released Darwin’s Paradox: An international science mysteryhttp://amzn.to/2k8qJgi. When the pandemic strikes, the medical doctors are forced to look for more and more unlikely causes.

New medical students are regularly warned that when they hear hoof beats, they should think of horses, not zebras. Before they get their clinical experiences, new doctors treat all diseases as equally probable. After they become experienced, they naturally think of horses (the common causes) when they hear hoof beats (common symptoms).

This leads to an opposite problem. Experienced doctors have a blind spot when the hoof beats actually foretell zebras (a rare disease).

Consider this case from Canadian Journal of Infectious Disease, Volume 13, Number 2, March/April 2002.

A nine-year-old boy had upper arm pain and a slight fever. In a few days the pain extended down to his wrist and up to his shoulder and neck. The area was tender to touch and prevented him from sleeping. The next day he had tremors and was hospitalized.

This was followed by sore throat, difficulty swallowing, and intense itching. The doctors considered allergies and treated his with diphenhydramine (an antihistamine) which had little effect.

The tremors and spasms got worse, and the patient had difficulty speaking. Knee-jerk reflexes were normal, but the doctor considered epilepsy and ordered an electroencephalogram. This showed a slowing of brain activity, but not epilepsy.

The patient next developed aerophobia (fear of air blown on them) and hydrophobia (inability to drink water). This was accompanied by a rash, transient hallucinations, and intense itching.

The following day brought severe tremors of the face and all limbs, drooling, priapism, and the feeling of suffocation. At this point the doctors presumed that the patient had rabies.

Nine days later, “14 days after the onset of his initial symptoms, the patient presented a clinical picture compatible with brain death, was extubated and died.”

This is an example of how difficult it is to diagnose rabies, absent a reported bite.

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Here is another case from CDC Morbidity and Mortality Weekly Report, Volume 60, Number 14, April 15, 2011.

“The patient reportedly had awakened with a bat on his arm 9 months earlier, but had not sought medical evaluation. He went to a local emergency department (ED) on October 30 and soon after was hospitalized; he died 12 days later.”

Initially he was treated by a chiropractor for pain and numbness of his left hand and arm, lower neck and upper back. The chiropractic treatment relieved the back pain, but the arm numbness and tingling got worst.

At the hospital, the patient did not have a fever, blood pressure was normal, blood count and routine chemistries were normal. Strength and sensation were normal. The only symptoms were weakness of the left arm, elevated white blood cell counts, and elevated glucose. A CT scan also revealed some anomalies.

Most concerning, the patient had such difficulty breathing that he was put on ventilation.

AIDP and Guillain-Barre syndrome were the chief diagnoses considered at this point. MRI and entectromyography pointed to AIDP and treatment began.

A few days later, with the patient not improving, CSF (cerebrospinal fluid) analysis lead the staff to switch the diagnosis to meningoencephalitis. This treatment was also not effective.

At that point, “on November 4, the infectious disease physician asked the patient’s wife about any animal exposure history. … The wife had no knowledge of any recent animal bites. …
On November 8, another relative recounted an incident that had occurred approximately 9 months before onset of illness. The patient had told the relative about waking one night to a bat crawling on his arm. …
On November 11, the patient’s family elected to withdraw life support, and the patient died shortly afterward.”

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Here is a third case from CDC Morbidity and Mortality Weekly Report, Volume 59, Number 13, April 9, 2010.

When an apparently healthy man visited a clinic with fever and a cough, the clinician diagnosed bronchitis and prescribed antibiotics.

By the follow-up, the patient now had fever, chills, chest pains and left arm numbness. An electrocardiogram did not indicate a heart attack. The diagnosis was musculoskeletal pain and the patient was prescribed pain killers and muscle relaxants at this time.

Next visit the patient was agitated and restless, which was presumed to be a side-effect of the muscle relaxants. Hospital observation was recommended, but the patient went home.

The next day, the patient presented with twitches, high heart rate, low blood pressure, and fever. The doctor now considered sepsis and the patient was hospitalized.

The patient was intubated and tested extensively. The patient continued to deteriorate with low heart rate, low blood pressure, muscle wasting, and kidney failure requiring dialysis.

Two weeks after the initial clinic visit, rabies were considered. The patient died the next day.

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Sometimes those hoof beats are zebras.

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Live Long and Prosper #science #health

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In the last two centuries, life expectancy has more than doubled from under 40 to over 70. This is the difference between parents burying their children and children not knowing both parents to today where grandchildren and grandparents are commonplace.

What has caused this dramatic extension in life expectancy? What has made living beyond 100 more common and childhood death more rare?

One suggestion might be antibiotics.

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20th century medicine was about antibiotics. Starting in 1911, over 100 different antibiotics were released. Some of the big ones were penicillin, tetracycline, doxycycline, amoxicillin, ciprofloxacin. Anitbiotics treat a wide range of diseases including: anthrax, whooping cough, pneumonia, botulism, and STDs. If you plan an international vacation, your doctor will give you ciprofloxacin for “traveler’s diarrhea.”

None of this would have been possible were it not for the 19th century discovery: GERMS! For 1000s of years prior to the 1800s, western medical theory was about humors. Health was controlled by the four humors: black bile, yellow bile, phlegm, and blood. When the humors were in balance you were healthy.

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When they were out of balance, you’d get sick, and you might be told to exercise more, eat healthier, be positive, pray, or if you could afford it, a doctor might try to balance the humors with medicines and procedures. These included bleeding, laxatives, and expectorants.

Before we laugh at two millenia of western medical science, reread that previous paragraph. Much of that advice, with the exception of bleeding, is still offered today. Thus, if we are honest, we can see the attraction of this commonsense medicine that let so many die.

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The 19th century changed all this (or did it?) with the discovery of specific germs for “anthrax, cholera, tuberculosis, leprosy, diphtheria, gangrene … plague, scarlet fever, tetanus, typhoid fever, pneumonia, gonorrhea and meningitis.”

This was all good, but germ theory and antibiotics only sometimes helped when people got sick. Penicillin was given credit for saving many lives in World War II, but the real gains came from preventions more than cures.

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The reasons that so many children and grandparents are alive is the long list of diseases that people growing up today have never seen — all thanks to vaccines.

Children are routinely protected from: chickenpox, diphtheria, influenza b, hepatitis A and B, measles, mumps, whooping cough, polio, pneumoccal, rotavirus, rubella, and tetanus. If you don’t recognize some of these diseases, it is not because they aren’t terrible or contagious, but because of vaccinations.

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Beyond these vaccines, if you are going to travel you might also get shots for meningitis, typhoid, and yellow fever.

The extension in life expectancy is not about cures, but about prevention.

The history of vaccination peaked during the period of 1880s (rabies) to 1950s (polio). However smallpox vaccination started much earlier in Asia with clear documentation in China during the 16th century, and vaccination development continues today, especially with the efforts to prevent Malaria.

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