POLIO RESEARCH IN STH. AFRICA SHOWS MARKED ADVANCES

Gisborne Herald, Volume LXXVI, Issue 22890, 9 March 1949, Page 4

POLIO RESEARCH IN STH. AFRICA SHOWS MARKED ADVANCES

(From Reuter’s Correspondent in Cape Town)

Research work into the nature and means of combating poliomyelitis—infantile paralysis—is more advanced than is commonly believed, according to two prominent South African doctors engaged in medical research.

Dr. E. H. Cluver, director of the South African Institute for Medical Research, in a speech at the first meeting of the poliomyelitis research foundation recently, stated that from knowledge already available it can be said that the cause and vaccine for this disease can be discovered just as the causes and vaccines of other epidemic diseases have been discovered.

He added that South Africa is ar* ideal country in which to carry out research into the causes of poliomyelitis. Not only has the research workers of international reputation for similar work on virus diseases and a good supply of monkeys—the only organisms, except man, attacked by the disease — but also a multi-racial society of which one section, the Bantu, is not susceptible to the disease. v A sum of £500,000 is needed to undertake the necessary research. Some £27,000 has already been contributed towards it. Highly Resistant Virus

Dr. James Gear, also of the South African Institute of Medical Research, in a paper read at the recent South African health congress, reported on the results of the latest research into the nature of the disease. The reasons for the seasonal incidence of poliomyelitis, he said, are still not known, but it has been established that the disease is due to one of the smallest known viruses and one of the most resistant viruses.

At room temperature, the virus survives for many weeks and in a refrigerator for many months but it is readily destroyed by heat —in half an hour at 60 degrees centigrade (140 degrees Fahrenheit)—and also by direct sunlight and ultra-violet light. Earlier observations suggested that it survives treatment with one part of chlorine to one million parts of water, but more recent studies indicate that this concentration of chlorine in purified water renders the virus inactive. This, Dr. Gear stated, is reassuring to know because of the possibility of the spread of infection by water or through swimming baths. The way in which poliomyelitis spreads remains a vexed question, but certain facts have been ascertained by research workers. In patients dying of the disease, for example, the virus has been found to have a selective affinity for the motor cells of the grey matter of the spinal chord and brain stem. Family Contacts Infected

The destruction of these cells is responsible for the paralysis characteristic of the paralytic form of the disease. In patients suffering from the disease, the virus has been found in the throats and repeatedy from the faeces of apparently healthy contacts of cases. Intimate family contacts are especially liable to be infected.

“In our investigations,” said Dr. Gear, “twelve families, in each of which a paralytic case had occurred, were investigated. In each instance, it was found that other members of the family were also infected, although most of them had no symptons of illness. Intimate association appears to be an important factor. There is much lower incidence of infection among extra household contacts and a still lower incidence among non-contacts in the same neighbourhood. “The majority of oe<'ol« affected with the virus of poliomyelitis. have no symptoms. Laboratory studies indicate that for every person with recognisable svmntons, there are 10 infected individuals with no obvious illness.” Possible Contamination

It may be concluded, Dr. Gear continued, that the human tank effluent from a septic tank might contaminate streams and, if used for irrigation, might contaminate vegetables and fruit. Unless cooked, such vegetables and fruit would be possible sources of infection.

The records of the 1944 and 1948 epidemics in Johannesburg did not show any correlation between the distribution of cases and their water supply. Nor did the analysis reveal any common source of milk or fruit supply in the outbreaks. On a number of occasions, vegetables and fruits from plants and trees irrigated with the human tank effluent, were tested, with negative results.

Flies have for long been suspected of being concerned in transmitting the disease, and further investigation is needed to elucidate this matter, Dr. Gear declared. Against the hypotheses that flies often are concerned in the spread of disease, he explained, is the fact that the thorough application of D.D.T. to affected areas had little effect on either preventing or cutting short epidemics. Nor, Dr. Gear added, can any conclusion at present be drawn concluding the effect of the weather upon the incidence of infection, although regular examinations of sewerage in Johannesburg had clearly demonstrated that widespread infection did not persist during the winter months or non-epidemic summers- There is no evidence, either, to incriminate migratory birds in t'ne spread of the disease. A larger proportion of Bantus than Europeans are immune from the disease. In the case of adults, nearly 100 per cent of Bantus are immune and approximately 80 per cent, of Europeans. “It has long been suspected that fatigue and shocks may precipitate a paralytic attack of poliomyelitis.” said Dr. Gear. "It has been clearly demonstrated that severe or prolonged exercise during the early stage of the illness pre-disnoses an individual to severe paralysis. Long, tiring journeys by train, motor car. bicycle or on foot have a similar effect."