Polio in Argentina

[njolene]

http://www.medicalnewstoday.com/articles/152565.php

"The Buenos Aires Herald reported that this is the first case of polio in the country in 15 years (Buenos Aires Herald, 6/2) while Prensa Latina reported that it was the first case in 25 years (Prensa Latina, 6/2)."

[carriebft]

I am assuming this is wild polio or we would be hearing it; I also am told by Argentinian relatives that their kids have been given the IPV, so that would also suggest wild polio.

If it is confirmed to be wild polio, that would mean the first case in the Western Hemisphere in a long time and we will no longer be hearing how polio-free our hemisphere is...

[njolene]

I hope more details come out to clarify.

[ema-adama]

Argentina : On Tuesday, Argentina's Public Health Ministry issued a warning and highlighted polio prevention recommendations after an infant was diagnosed with polio in San Luis province, Prensa Latina reports. The child had a "rare pathology that altered his immune system and allowed the onset of polio," according to Prensa Latina. The WHO recommends that 95 percent of infants and school-age children receive vaccinations in order to effectively prevent the spread of the disease. A health worker said vaccination efforts in Argentina need to be scaled up because some areas only have 85 percent coverage (Prensa Latina, 6/2). The Buenos Aires Herald reported that this is the first case of polio in the country in 15 years (Buenos Aires Herald, 6/2) while Prensa Latina reported that it was the first case in 25 years (Prensa Latina, 6/2).

Underlining mine. From the vaccine? or is this wild polio? Are they implying that a child with a healthy immune system would not have developed polio?

[carriebft]

Well, an unhealthy immune system is a risk factor for developing paralytic polio. That was how I read that.

Still waiting for information concerning the type of polio.

[carriebft]

It looks like many areas of Argentina still use OPV:

http://www.who.int/vaccines/globalsu...%3FC=%27arg%27

So I think this may very well be a vaccine related case since what little googling I did about the area it was seen seems like it is not a very developed area and probably is not an IPV use area.


Yup, vaccine derived according to this:

La Sociedad Argentina de Pediatría (SAP) aconsejó que la vacunación en los niños complete al menos el 95% de cobertura y al referirse al caso del bebé que enfermó en San Luis de poliomielitis recordó que lo importante es que no se trata de "polio salvaje", sino de un virus Sabín derivado.

If my translation prowess is correct...

[njolene]

Thanks for finding that Carrie. I have no idea about the translation.

[carriebft]

I'm married to a man who speaks fluent spanish and I spend a lot of time in central america, but I am not fluent myself. But I believe it says it is not wild polio but polio derived from the Sabin vaccine.

[carriebft]

again translating here with my somewhat limited skills...another article:

"El nene se contagió porque el virus estuvo mutando por varios departamentos del país donde la cobertura de la vacuna Sabin es menor al 95 por ciento. Así, durante los últimos tres a cuatro años el virus estuvo mutando a través de las heces y aguas contaminadas de chicos y adultos sin protección de la vacuna. Eso indujo una mutación en el virus y la reversión de su virulencia. El bebé de San Luis se contagió un derivado de la vacuna Sabin. En el se comporta como polio salvaje y le produjo parálisis en una de sus piernas", indicó a Clarín el director nacional de epidemiología del Ministerio de Salud de la Nación, Juan Carlos Bossio.

http://www.clarin.com/diario/2009/06...m-01930773.htm

So they are saying this was vaccine derived and that it mutated in the environment and can be caught once polio vaccination falls below 95%.

anyone tell me more about this, specifically the mutation part...the child didn't catch it from the vaccine itself but from the environment, but the virus in the environment was vaccine derrived originally?

[ema-adama]

Originally Posted by carriebft

So they are saying this was vaccine derived and that it mutated in the environment and can be caught once polio vaccination falls below 95%.

anyone tell me more about this, specifically the mutation part...the child didn't catch it from the vaccine itself but from the environment, but the virus in the environment was vaccine derrived originally?

I wonder if we will ever know if this child had been vaccinated or not, and if so which vaccine was used?

I did find this:

I don't understand how children who have been vaccinated for polio several times can not be immune to polio. I was under the impression that the vaccine is very effective at conferring immunity.

[ema-adama]

http://indianpediatrics.net/may2003/may-455-462.htm

The vaccine genotypes are unstable and vaccine viruses may, and usually do, back-mutate quite often to increasing neuro-virulence during multiplication in the human host(11). In Japan, where wild viruses were eliminated many years ago, river and sewage waters carry vaccine-derived viruses shed by vaccinated children(12). Among the strains of polioviruses in the environment, 69% of type 1, 92% of type 2 and 55% of type 3 viruses were found to be neurovirulent revertants (12). This is clearly a signal for the hidden risk inherent in the continued use of OPV. As long as immunity levels are maintained high with early vaccination of all children, the risk of infection by vaccine-derived neurovirulent mutants will remain low. However, if vaccination slackens, then the risk of infection from environmental source may increase.

Not that reassuring.....

The second problem is chronic infection and prolonged shedding of vaccine-derived revertant viruses by a small number of individuals with primary immuno-deficiency(16,17). So far 19 cases have been described, each person shedding virus for a few to several years (Wood D Personal communication, 2002). They were detected in England (8 cases), USA (7 cases), and in Japan, Argentina, Taiwan and Iran (one case each). The longest recorded duration of chronic infection and virus shedding in one individual is 15 years(17).