Nexus - 0303 - New Times Magazine-pages

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reported in persons who had a history of swimming in lakes and _ mentioned that amoebas were isolated originally from the monkey swimming pools. However, a number of cases were also reported _ kidney tissue but did not consider a very likely administration of im persons with no history of swimming prior to the onset of the the polio vaccines as a possible source of amoebas in children disease. Also, many strains of Acanthamoeba, including some _ below the age of four, one or even below the age of six months. with proven animal pathology, have been recovered from the Apley et al. (1970) diagnosed meningoencephalitis due to an noses and throats of human volunteers without clinical disease. amoeba (Naegleria) in a little boy aged two years and nine Wang and Fieldman (1967) isolated altogether 54 strains of months. He had one week's history of anorexia, mild irritability free-living amoebas of the genus Hartmanella (= Acanthamoeba) and slight sore throat. On the day of the admission, the baby com- in tissue cultures inoculated from pharyngeal swabs obtained for _ plained of headache and more severe sore throat and was pre- the study of viral respiratory diseases from 1958 to 1962 in fami- scribed oral penicillin. He became progressively ill and vomited lies residing in two city-operated, low-cost apartment complexes. all food and liquids taken. Attacks of intermittent pallor and hot All cultures were examined microscopically for three to four flushes were noticed by the parents. Lumbar puncture yielded a weeks. Amoebas of the genus Hartmanella were demonstrated in fluid, and amoebas were identified in it. The child progressively 40 culture swabs from 38 subjects (two of them had positive cul- deteriorated and dicd on the sixteenth day of illness. tures on two occasions). Most isolations (82%) were made from However, two other patients (Case 2 and Case 3) recovered. those four years of age and younger. Within this age range, chil- | Case 2 was a six-year-old brother of Case 1. He suffered symp- dren one and two years old contributed the majority of identified toms of meningoencephalitis and recovered 12 days after hospital amoebas. admission. Amoebas were cultured from his CSF. Ten days after The relation between age and the occurrence of amoebas was __ recovery, a further lumbar puncture yielded a normal CSF without analysed further by comparison of the ratios between actual and —_ any amoebas isolated. expected isolations within age groups. Again, children under five Case 3 was a four years and five-months-old boy, a neighbour years of age were more apt to be of cases 1 and 2. Two days before affected, those under one year being admission he had had a booster most involved. ‘ ; ¥ dose of DPT vaccines. Initially, For some undetermined reason, It is also quite well established that amocbas were reported in his CSF; isolation rates fell sharply during amoebas are important however, samples taken on the 1963-1966. However, some alter- ee it eighth, fourteenth and twenty- ations in the swabbing and testing contaminants of tissue cultures used fourth days were all normal and no procedures and incubation tempera- | in preparation of live biologicals, amoebas were isolated. ture were made during this time . . * because of changes in cell lines, con- | VACCINES being the most important J optic xeratosis CAUSED tamination catastrophes and moving of them because they are widely BY AMOEBAS in a new building. Also, the study Cee . * With the introduction of soft population during this period con- injected into small babies and optic lenses, reports of eye kerato- tained about eight per cent fewer children. sis started filling pages in medical youngsters in the group of one to four years old compared with the previous years. However, an alternative explanation is possible. In the above SUMMARY time interval, the US switched from the injectable Salk vaccine to Amoebas are quite obviously widely spread protozoans and the oral Sabin vaccine. It stands to reason that since amoebic some of them have been established as causing serious disease in forms are dissolved by bile, fewer specimens would pass into the animals and humans. It is also quite well-established that amoc- body of the oral vaccine recipients compared with the recipients of bas are important contaminants of tissue cultures used in prepara- journals. Amoebas were identified as the causative agent. the injectable polio vaccine. tion of live biologicals, vaccines being the most important of them The authors summarised that free-living amoebas are primarily because they are widely injected into small babies and children. found in soil and water, and it is reasonable to assume that they Even the above short review of some of the existing literature are acquired by man through oral contact with soil. This concept indicates that a great number of cases of meningoencephalitis and was supported by the large proportion of isolations from children _ serious respiratory infections in small babies and children can be in the crawling age group. But the explanation of two isolations __ linked to administration of vaccines which have a high potential to from infants less than six months of age posed a problem. So, be contaminated by amocbas, cither directly from the culture tis- they concluded that they have not been successful in relating the sues or from culture tissues contaminated by amoebas from the air presence of amoebas in the throat to the respiratory disease. and surrounding laboratory surfaces. Again, at the time of this study, polio vaccination in the US was It is also clear that although a number of victims recover, the accepted by a great majority of parents and it is very likely that all majority succumb. Vaccine-producing drug companies should babies in the age group below six months were vaccinated on add warnings about this possibility on the product inserts of their time. This would plausibly as well as unequivocally explain the — vaccines and inform parents of the possibility of invasive amoebic occurrence of amoebas in the throat swabs from the young babies. | meningoencephalitis. About one third of the subjects had symptoms of respiratory dis- This further highlights the need for prudence on the part of ease at the time of positive cultures, but so did many others with- _ health authorities in Australia and elsewhere who, for yet another out amocbic isolations. Several attempts to measure antibody imperative reason, should drop their national immunisation pro- response to each of the species of amoeba ended in indecision. grammes. eo The authors were unable to conclude that infection rather than Continued e 85 infestation occurred or that immunity was acquired. The authors APRIL-MAY 1996 46 ¢ NEXUS Continued on page 85