Posts Tagged With: Diagnosis

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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