1937 Erstfeld outbreak

In July 1937, 130 of 930 soldiers stationed in the small town of Erstfeld, Switzerland became ill with what the time was thought to be "Abortive poliomyelitis."

Onset
Four days after training commenced the troops were all wet through on a field exercise. Two days later, a case of poliomyelitis occurred among them, this case was at once diagnosed and removed to hospital. This was followed within twelve days by six cases with meningeal and myelitic symptoms, 16 purely meningeal cases and 108 with symptoms involving inflammation of the upper respiratory tract. The incubation period was 4-7 days.

Symptoms
Of the 130 cases, 83 percent had systemic symptoms and were regarded as abortive poliomyelitis ; 12% had meningeal involvement (involvement of the lining of the brain and spinal cord); and 5% developed encephalomyelitis with paresis (muscle weakness caused by nerve damage or disease or partial paralysis).

Symptoms included:


 * Sweating
 * Sensitivity to touch, pain, or other sensory stimuli
 * Diminished muscle tone was noted in those who complained of sharp pain in their legs.

Findings
The cerebrospinal fluid was normal.

Epidemiology
This outbreak was notable for its high attack rate: 14% of soldiers were affected, as compared to 1.3% for a confirmed poliomyelitis outbreak in 1936. (This was a common feature of epidemic myalgic encephalomyelitis that distinguished it from polio outbreaks.)

The troops had been recruited in Zurich, where a case of the disease was reported on July 11th. The epidemic did not spread to any citizens of the town. A similar epidemic was recorded in September, 1937, less than three months later, in the women's section of a St. Gallen hospital, Switzerland, less than 200 km or 125 miles away from Erstfeld.

Prognosis
The meningeal and upper respiratory forms cleared up in 2-5 days and all cases recovered within five weeks. There were no deaths and no residual paralysis.