Think twice before using a conclusion
Direk Limmathurotsakul
Dear everyone,
I have come across this article at PMC. As it’s open-access, it is attached here. The article used a modelling approach, quantified a population of asymptomatic melioidosis patients, and, then, quantified the level of potential melioidosis spread caused by asymptomatic melioidosis patients (i.e. latent infection); and, finally, recommended that “treatment of asymptomatic patients needs to be scaled up to minimize the spread of melioidosis.” ??? It is quite mind boggling that I want to ask how we should think about it.
The model seems complex and difficult to crack. I dug into the article a bit and my simple questions are
[1] Do anyone really have any tangible evidence that patients with latent infection can spread melioidosis significantly? (For “tangible”, I mean, Do any one see and publish any case reports of transmission from latent infection to a new human melioidosis cases)
[2] Human-to-human transmission is already so rare. How come the model assumed that patients can get infected from direct contact with ‘asymptomatic’ melioidosis patients?
This is shown on page 2: assumptions used in the model:
The modelers may state that the models are to estimate things that we have never observed. For this one, I personally think that the model should not model a phenomenon that has never been observed -> then assumed that both asymptomatic and symptomatic patients spread diseases to other new cases at the same rate (𝛽2) then assumed the value of such rate (𝛽2= 0.00077, Table 3 [assumed]) and then quantified that that this rare-to-never-observed phenomenon is big and crucial.
Nonetheless, if in the future, we have more evidence that people can (a) diagnose latent infection accurately and (b) prove that a proportion of patients/animals with latent infection can spread disease to new human cases, new animal cases and/or new environment; then, we will definitely need to model whether we need to intensively diagnose and treat latent infection to prevent spread.
In conclusion, I would like everyone to think twice before using the conclusion of the article at this point.
Kind regards,
Direk
PS.
1. I could be wrong, and happy to hear your thought.
2. Please note that discussing together via melio...@googlegroups.com will be open-access.
3. Separately, I think that any in-vivo or in-vitro studies to evaluate when and how patients with latent infections would develop exacerbation of melioidosis, so that we can treat latent infections when they are at risk of developing exacerbation of melioidosis (e.g. a surgery, etc.) is more crucial at this point.
David Dance
Thank you Direk. I can’t comment on the modelling itself, which goes way over my head, but models are based on assumptions and if those assumptions are wrong then the model will be meaningless.
As George Box said, “All models are wrong, but some are useful”. Personally I don’t think this is one of them.
BW
David
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Lek
Dear Dr. Direk and Dr. David,
I agree with your comments and I think that their hypothesis without strong evidence may cause a big misunderstanding in the community. So far, we have never heard that the melioidosis patients in the wards spread their disease to the close patients or healthcare workers who look after them.
Should we send the comments to the authors or the journal?
Thank you very much,
Lek
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Robert Norton
Thank you Direk for bringing this to our attention. Agree, it is misleading and has the potential to cause anxiety. Can this be brought to the attention of the journal? Perhaps a joint letter?
Regards
Robert
Dr Robert Norton
Director of Microbiology and Pathology
Townsville University Hospital
100, Angus Smith Drive, Douglas,
Townsville, Queensland 4814
Australia
Tel:(+61) 0744333446
Mobile: 0419672617
Fax: 07 4433 2415
Email: Robert...@health.qld.gov.au
From: melio...@googlegroups.com <melio...@googlegroups.com>
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Subject: [Melioidosis] Think twice before using a conclusion
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Fazle Rabbi Chowdhury
Sent: Tuesday, November 29, 2022 1:23:06 PM
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Subject: [Melioidosis] RE: Think twice before using a conclusion