1949-53 Adelaide outbreak

From 1949 to 1953 in Adelaide, Australia, there was an outbreak of a disease resembling poliomyelitis, during and after a poliomyelitis epidemic. In August of 1949, cases of myalgic encephalomyelitis began to appear and continued to be seen until 1951, by which time 800 patients had been admitted to Northfield Infectious Diseases Hospital. Patients has slight, diffuse muscle weakness mainly affecting the legs, In some, weakness appeared for the first time up to three months after the onset of the initial symptoms.

The male : female ratio was 1: 1.

1951
30th June 1951

"The author describes a disease which has been epidemic in Adelaide since August 1949, and which closely resembles poliomyelitis. Its most characteristic feature is the absence of abnormal findings in the cerebrospinal fluid. Thus, out of 1,350 consecutive cases of " poliomyelitis ", 800 had less than 10 cells per cubic millimetre in the cerebrospinal fluid (the majority had less than 5 cells); and the protein values were normal in all but 2 of these cases.

The onset of this illness was either gradual or sudden and, if sudden, headache was a constant feature and often of marked intensity. Muscle weakness - generally slight and diffuse in distribution - occurred more commonly in the legs than in the arms. Where paralysis was severe, rapid recovery generally ensued. Two noteworthy features of the muscle involvement in this disease were as follows: the pain frequently persisted in various muscles for periods up to six months after the acute illness; in some cases the onset of muscle weakness was delayed for several months. The ultimate prognosis was always good, but frequent recurrences were not uncommon. The greatest disabling feature of the disease lay in the psychological sequelae which were fairly constant and comprised one or more of the following - lack of concentration, depression, irritability, emotional instability and hyperacuity of hearing. These manifestations, however, eventually resolved completely".

1952
1st February 1952

"Dr. R.A. Pellew, of Adelaide, who will also address the conference, believes that most of SA's 3,130 polio cases during the past two years and nine months have suffered a mild form of the disease."

1955
The Adelaide outbreak of atypical polio was associated with a reduction in typical polio cases. "There was ... a marked regression of [typical] poliomyelitis in South Australia (413 notifications as compared with 721)." (from page 645 of 1955 WHO report )