Polio and improved hygiene

[MamaMunchkin]

Recently, from another thread:

“If the drop in disease were due to hygiene and sanitation, you would expect all diseases to start going away at about the same time. But if you were to look at the graph for polio, for example, you would see the number of cases start to drop around 1955 – the year the first polio vaccine was licensed. If you look at the graph for Hib, the number drops around 1990, for pneumococcal disease around 2000 — corresponding to the introduction of vaccines for those diseases.”

Unless ... what if the incidence of polio - increased - due to improved hygiene ... unlike many other infectious diseases ...

I recently came across the idea and would like to learn more about it.

This idea is mentioned here:

Salk Vaccine Trial

http://wps.aw.com/wps/media/objects/14/15269/projects/ch12_salk/index.html

From the same source above:

Strangely enough, severe polio tends to be rare in communities with poor hygiene. The reason is that the virus is abundant in such communities, so babies are likely to be exposed to the virus early, while still protected with antibodies from their mothers. Later (assuming that they survive other diseases associated with poor hygiene), these children develop their own antibodies to the virus. The net effect is that in communities with poor hygiene, most people have a natural immunity.

Can anyone pls share some sources etc that might support/refute this claim? 

[MamaMunchkin]

I found this ... but love other sources as well ...

Immunological Basis for Immunization - Module 6: Poliomyelitis
http://www.who.int/immunization/documents/WHO_EPI_GEN_93.16/en/index.htm

... "sero-epidemiology in the prevaccine era" ... looks promising ...

[Rrrrrachel]

Yeah I've read about this before. I think the theory is that low levels of virus and exposure to open sewage kind of worked to inoculate people? So improved hygiene left them more exposed.

[MamaMunchkin]

So, polio has been a problem in some underdeveloped countries, e.g. some in West Africa ... I wonder how the sanitation condition where recent outbreaks occured compared to the sanitation in the US, say, between 1900-1950 when polio was a problem ... 

[Bokonon]

Originally Posted by Rrrrrachel 

Yeah I've read about this before. I think the theory is that low levels of virus and exposure to open sewage kind of worked to inoculate people? So improved hygiene left them more exposed.

Source?

[WildKingdom]

Edited for double post

[WildKingdom]

Originally Posted by Bokonon 

Source?

http://www.who.int/vaccines-documents/DocsPDF-IBI-e/mod6_e.pdf

[Suvroc]

This is from CDC pinkbook.

"Before the 18th century, polioviruses probably circulated widely. Initial infections with at least one type probably occurred in early infancy, when transplacentally acquired maternal antibodies were high. Exposure throughout life probably provided continual boosting of immunity, and paralytic infections were probably rare. (This view has been recently challenged based on data from lameness studies in developing countries).

In the immediate prevaccine era, improved sanitation allowed less frequent exposure and increased the age of primary infection. Boosting of immunity from natural exposure became more infrequent and the number of susceptible persons accumulated, ultimately resulting in the occurrence of epidemics, with 13,000 to 20,000 para-lytic cases reported annually."

It's interesting to me that they note the challenge (text in bold) but don't give you any reference so that you can look into that data.

[Bokonon]

Thanks!