It is generally asserted that all smallpox carriers are symptomatic. But what is the actual evidence for this? This is an absolutely crucial assumption, and, if wrong, makes the epidemiology of smallpox uninterpretable. Many experts were taken by surprise when asymptomatic COVID transmission was discovered.
Com a vigência da pandemia que estamos vivendo, esperamos que não tenhamos que lidar com o retorno de uma doença há mais de 40 anos erradicada, como a varíola. Embora seja uma doença que apresenta sintomas cutâneos bem específicos, alguns guias falam na possibilidade sim, de termos pacientes assintomáticos.
"some guides speak of the possibility of having asymptomatic patients."
The sources I have read say there were none. However, I have been having another think about it.
When there was a smallpox epidemic, there were local concentrations of virus. Those who inhaled large amounts got the disease. But what about the far larger number of persons who inhaled lesser amounts? I cannot see any reason why they could not reexpel the virus.
You cannot have evidence that something does not exist. All you can have is the absence of evidence that it does exist.
Hello prof sir
Smallpox exist only in war (bio terrorism). Many references said no asymptomatic carrier.
https://www.cdc.gov/smallpox/clinicians/clinical-disease.html
The vast majority of cases of Smallpox during the last outbreaks in Somalia and even before, in Ethiopia , India and Bangladesh were investigated and infeccious contacts(index cases in the outbreak)could be traced back, all syntomatic and unvaccinated. For more details refer to Smallpox and its eradication by Fenner, Henderson et al.
"all syntomatic and unvaccinated"
I thought smallpox was eliminated by ring vaccination, ie vaccinate everyone around an outbreak, irrespective of their status, which was therefore irrelevant.
Yes, by containment vaccination, isolation of patients and tracing contacts.
"Yes, by containment vaccination, isolation of patients and tracing contacts."
Since the team did not need to know if there were any asymptomatic spreaders, I don't see how any conclusion about their existence can be drawn from this trial.
Just like Jenner's study, I don't think this trial met modern ethical standards of informed consent. The villagers must have been strongly 'persuaded' to be vaccinated. In fact, side effects from the vaccine to the individual probably outweighed the small likelihood of the natural disease. (I am currently not intending to have a COVID vaccine since I suspect my risk of catching COVID in a Medical Centre outweighs the protection from the vaccine).
Nevertheless, I consider the elimination of smallpox to be the greatest medical accomplishment of all time, a case of the ends justifying the means.
According to available evidence, smallpox has been eradicated as population disease since 1979? One the criteria for its being eradicatable disease is the lack of reservoir other than humans. Regardless of the whether it has asymptomatic carriers or not , the infection has been eradicated and no evidence of transmission is reported. Therefor absence of any case during the last 40 years dismiss the view of the existence of asymptomatic carriers.
As a matter of fact the last case of Smallpox was in Somalia in October 1977. Two years of intensified search for suspect cases and poxmarks surveys prepared the ground for international comission of experts to declare smallpox eradicated globally in 1979. In 1980 the World Health Assembly declared the eradication of the Smallpox virus and the disease. The methodology of containment and surveillance applied were not "trials", but eradication strategies which proved effective.
"absence of any case during the last 40 years dismiss the view of the existence of asymptomatic carriers"
It is pretty certain that there have been no recent cases of symptomatic smallpox. So why on earth would anyone expect there to be asymptomatic cases nowadays? In the old days, asymptomatic cases are unlikely to have been very common, yet could have been important for spreading the disease.
To encapsulate my argument, the WHO strategy would work regardless of how many asymptomatic carriers there might be.
Assyntomatic cases were not found during Smallpox Eradication and that applies to Measles elimination as well.
- Badges
- Science topic
- Similar topics
- Medicine
- Epidemiology