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Feature Polio

Polio eradication: a complex end game

BMJ 2012; 344 doi: (Published 02 April 2012) Cite this as: BMJ 2012;344:e2398

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Re: Polio eradication: a complex end game

Eradication of polio by vaccination - Part 4

Contamination of monkey kidney tissue cultures (used in the production of polio vaccines) by live amoebas.

In 1996, while watching a TV news report on the death of two 5-year olds in Australia from brain-eating amoebae, I remembered a note in Hull et al.'s paper (1958. New viral agents recovered from tissue culture of monkey kidney cell. Am J. Hyg; 68: 31-44): “Recently, an amoeba was isolated from monkey kidney tissue cultures and was identified as belonging to the genus Acanthamoeba. It grew readily in tissue cultures…It appeared to have the ability to infect and kill monkeys and mice following intracerebral and intraspinal inoculation.”

Amoebas are unicellular protozoan microorganisms. According to Ma et al. (1990. Naegleria and Acanthamoeba infections: Review. Rev Infec Dis; 12 (3): 490-513), they are classified in the phyllum Sarcomastigophora and belong to Rhizopoda, equipped by propulsive pseudopodia and/or protoplasmic flow without production of pseudopodia. Acanthopodina, a suborder of Amoebida, form two families, Vahlkampfiidae and Acanthoamoebididae, with two genera Naegleria and Acanthamoeba respectively, with a number of species. Naegleria species form three life-stages, trophozoites, flagellates and cysts and Acanthamoeba species only two, trophozoites and cysts.

Jahnes et al. (1957. Free-living amoebae as contaminants in monkey kidney tissue cultures. Proc Soc Exp Biol. Med; 96: 484-488) isolated two strains of apparently the same amoeba which looked like round bodies, similar in appearance to cells manifesting changes induced by certain simian (monkey) viruses. On closer examination, they proved to be amoebic cysts. They varied in size, from 10 to 21 microns in diameter. In one experiment, the cysts were treated with 10% formalin, washed and inoculated into monkey kidney tissue culture tubes. The monkey kidney cells fagocytised the cysts. The trophozooites turned into cysts under refrigeration down to 4 degrees C. These were resistant even under –50 degrees C for months and survived in the pH range 5.0-9.0. Their tissue cultures were not affected by streptomycin and penicillin.

Culbertson et al. (1958. Acanthamoeba: observations on animal pathogenicity. Science 1958; 127: 1506) and Culbertson et al. (1959. Experimental infection of mice and monkeys by Acanthamoeba. Am J Pathology; 35: 185-197) confirmed that amoebas caused brain disease and death within days in monkeys and mice.

Following inoculations “extensive choriomeningitis and destructive encephalomyelitis occurred” and killed monkeys in four to seven days and mice in three to four days. Intravenous injections of the amoebas resulted in perivascular granulomatous lesions. Intranasal inoculation in mice resulted in fatal infections in about four days. These mice exhibited ulceration of the frontal lobes of the brain. There were amoebas in the lungs, and they caused severe pneumonic amoeba reaction. Haemorrhage was a common feature. Sections of the kidney showed amoebas present in the glomerular capillaries.

Amoebas showed the ability to migrate through the tissues. The size of the inoculum did not matter: both small and large inoculums produced amoebic invasions. Intragastric inoculations were unsuccessful most probably because amoebic cysts were dissolved by bile.

Researchers, as a rule failed to address the seriousness of the introduction into children of Acanthamoeba via the polio vaccines, even though they were aware of their origin from monkey kidney tissue cultures used in the production of polio vaccines. However they noted that the most contaminated age group were babies below the age of crawling – between 2 and ten months.

Live amoeabas were isolated from the air (Kingston and Warhurst 1969. Isolation of amoebae from the air. J Med Microbiol; 2: 27-36) in the UK, together with respiratory syncytial virus, and from the surfaces in hospital cubicles in which infants with acute bronchiolitis were being nursed,

The amoebas were isolated at Booth Hall Children’s Hospital in the cubicle occupied by a ten-week-old infant with acute bronchiolitis. First, only RSV was isolated and the child sent home, but later an unidentified cytopathic effect was noticed in the tissue cultures and was provisionally called “Ryan virus1” (Pereira et al. 1966, Ryan virus: a possible new human pathogen. BMJ 1Jan 15: 130-132), and later also in post-mortem bronchial swab of another seven-months old baby boy with RSV bronchiolitis.

Six days before admission, the baby developed a sore throat and ulcers in the mouth which later spread over the face; he was unwell, could not suck and developed loose stools. The day before admission, he developed a cough and started vomiting. He was drowsy and dyspnoeic, made jerky movements and died soon after admission. Necropsy showed some emphysema, petechiae and small areas of congestion and alveolar haemorrhaging in the lungs, a fatty liver, prominent mesenteric nodes, and mucopus in the ears. Escherichia coli bacteria were cultures from his ears. Death was diagnosed as due to a respiratory infection associated with encephalomyelitis and hepatitis. Vaccination status was not disclosed, although considering the age, the baby could have received up to three doses of DPT and OPV vaccines.

Armstrong and Pereira (1967. Identification of “Ryan virus” as an Amoeba of the genus Hartmanella. BMJ; 28 Jan: 212-214) identified the Ryan virus as Hartmanella castellanii. They had no doubt that these amoebas came from the human respiratory tract.

In Australia, Fowler and Carter (1965. Acute pyogenic meningitis probably due to Acathanoeba sp.: a preliminary report. BMJ; September 25: 740-742), Carter (1968. Primary amoebic meningoencephalitis: clinical, pathological and epidemiological features of six fatal cases. J Pathol, Bacteriol; 96 (1): 1-25) and Carter et al. (1981. A fatal case of meningoencephalitis due to a free living amoeba of uncertain identity, probably Acanthamoeba sp. Pathology; 13: 31-48) described a number of cases in children and adults.

Many cases all over the world occurred in children and adults, with, or without the history of swimming in lakes and public swimming pools. (Scheibner 1999. Brain-eating bugs: the vaccine connection. Nexus Magazine; (

Even if polio vaccines were effective in preventing polio paralysis, their potentially continued contamination by undesirable microorganisms (monkey viruses and amoebas) should encourage the abandonment of their use.

Well-meaning Rotarians should study the relevant medical research first, before engaging in global polio vaccination.

Competing interests: No competing interests

27 August 2012
Dr Viera Scheibner (PhD)
Scientist/author retired
Blackheath, Australia