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September 9 2007 Comments sent to from Ruth Watkins

I see that no virus has been recovered from the pipe or around FM1 manhole or the soil and that it is surmise that it leaked out into the soil. I am still surprised that no aliquot is kept of the large vessel cultures before they are inactivated. Also that no validation or accurate estimate can be made at all of the amount of virus not inactivated by citric acid from the vaccine tissue culture debris. Though the temperature of the holding vessel is said to reach 60 no time is recorded for this or monitoring in a verifiable way mentioned.

Also in the statements about FMD the amount of virus required to infect animals by various routes, inhalation and oral consumption is not mentioned at all. I think more detail could be given of the 1960 outbreak when one farm was infected 1.5Km from the animal house when aerosol release is thought to have been the cause. Was it cattle then? Were there other possible farms nearby not infected? Is there any resemblance to 2007 in the epidemiological pattern on the farms? I see there were 14 hours on July the 23rd when both farms could in fact have been simultaneously infected by the aerosol route.

It might be interesting to sequence viruses obtained from the cattle with reference to the order in which they were deemed to have been infected based on the stage of the lesions especially to look at the earliest infections. The virus in the group of four (B) is from a specifed bovine from the first farm but no other information is given which must be available. It might help clarify whether infection was from the same source or from farm1 to farm2. If from the same source this could have been by fomite transmission or by aerosol. However the dynamics of virus adaptation from a tissue culture strain to the animal strain, the heparan sulphate binding site amino acid change, could occur so quickly in the individual animal infected with the tissue culture strain that there could be no merit in analysing virus from different animals in the chain of infection. (within 24 hours humans given oral live polio vaccine shed virus in stool which has a reversion of a point mutation in the vaccine strain back to virus wildtype. Other point mutations of the vaccine virus have not reverted.)

Though they found no evidence of possible aerosol release they do not absoutely rule it out but think it unlikely whereas the transmission on work vehicle tyres from a leaking pipe or transported soil is considered more likely.

I have thought further about the aerosol route ie escape from the Merial facility for example. If everything was in working order etc it would be very disturbing to think this could have occurred, it would mean that none of the containment level 4 facilities could be deemed safe and also fly in the face of documentation and 'evidence'. (In 1960 a filter was missing from the animal house from which the virus is thought to have escaped in aerosol form.) I think it is difficult to get beyond circumstantial evidence of fomite contamination from the leaking drains. Perhaps a lot of molecular virology over a further period of time, investigating lab viruses, the farm viruses and even perhaps the animal experimental infection viruses using the IAH-M and even soil might make the molecular evidence firmer in a forensic way. Sometimes retrospect will help as in the case of the Hungary/Holton virus. Anyway the molecular biology doesn't contradict the hypothesis.




























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