it probably may be distribited by people who have these snails in their aquariums. Also it may be expansion caused by climatic changes or by human activities in the region.

Could you give more information about?

David,

I dont know if anyone is maintaining a look out for the species. Funding for research surveys is scarce if anywhere, but the matter is important, as the species you refer to also exista on Puerto Rico, and there is much traffic to the US from there. This is why "snails" are included in the warning on the entry to the US forms when travellling here from elsewhere.

Oned needs to be alert to this, and the best candidates will be the mosquito control personnel in the State, or else the State Parks system. Living in Maryland, I have no idea of their priorities.

The most common ways of spreading acidental Biomphalaria species relate to projects intended for breeding fish.

May be a lab strain. A similar story happened in Egypt few decades ago. It is possible to use molecular techniques to check the DNA figure-print. I think the best person in USA can help you is Eric Sam Loker in University of New Mexico. You can check my work also: http://www.ajtmh.org/content/73/1/131.long

this snail flourish in water containing vegetation. The snail uses it as shelter and place for its eggs. removal of such plants reduces the number of snails.

direct contact with water harbouring these snails should be avoided.

the changes in earth temperature, water projects like dams for example could be reasons for its appearance in such place.

I think trade in ornamental plants would be a risk for the snails But xisto would be unlikely to establish due to the good sanitation in Florida,

I agree. Because the good quality sanitation, hardly the presence of snail transmitted species of shistosomiasis result in the spread of disease on Florida.

There was a recent report of Biomphalaria glabrata in Mississippi at a sewage treatment plant. Check out this link at the USGA Aquatic Invasive Species website to get more information.

http://nas.er.usgs.gov/queries/SpeciesList.aspx?group=&genus=&species=&comname=planorb&Sortby=1

There are probably established populations in other states in the South as well. Florida has had previous introductions, but does not have established populations on record as yet.

Although the possibility of accidental introduction of B. glabrata in other tropical regions is not feasible for various reasons, because of ecological barriers hardly the species will be able to proliferation.

Schistosomiasis is found in Puerto Rico. Is that because there is poor sanitation there? What is different about Puerto Rico that allows the infection cycle to continue?

There are Biomphalaria-type snails permissive for a variety of helminth infections already in South Florida, although I don't know whether Biomphalaria spp. (e.g. glabrata and/or pfeifferi) are here, although I suspect they are. Large African snails were originally imported to be used in Voodoo and Santeria rituals; these have escaped and are invasive spp. here. They're permissive intermediate hosts for Angiostrongylus cantonensis and quite likely Schistosoma mansoni and S. intercalatum, as well. Also, the Miami Zoo has had Angiostrongylus transmission from infected animals into local rodent populations. JPCaruso, PhD, Veterinary Parasitology, University of Georgia, 1983

We have also conducted a study whereby Bulinus joussseaumei which is native of Central Africa were sampled from Nigerian freshwater bodies. We came into the conclusion that the snail species could have been introduced to the new environment from water current from bordering countries. The influence of dispersal agents of aquatic snails such as long distance migratory birds cannot be overemphasized. Small and young planorbids have been reported to be good colonizers because they are able to disperse on the feet and feathers of birds.Once in a new environment, their ability to self-fertilize, in addition to their wide tolerance of alkalinity, salinity and pollution, facilitates propagation and spread.

Dear All, especially Joseph Caruso: You need a malacologist to look at your snails. While B. glabrata is endemic in Puerto Rico, there are no records of it becoming established in Florida that I am aware of. Certainly there are pockets of Helisoma spp (the red spiral snail that is frequently kept in freshwater aquaria) but it is not a vector of schistosomes nor other trematodes. The African snail you mention is likely to be Achatina sp which is a vector of Angiostrongylus, but it has no role in schistosomes transmission, it is NOT aquatic! It is purely terrestrial. Also remember to complete the cycle there is a need for an influx of infected humans who urinate or defaecate in the water to produce miracidia. In the US people don't normally do that!

Clive Shiff, You point out that schistosomiasis transmission requires (in addition to the snail host) infected humans who urinate or defecate in the water to produce miracidia, and that US people don't normally do that. For this reason, schistosomiasis would not likely become established in the Southern US, even if Biomphalaria was present. The fact that schistosomiasis is endemic in Puerto Rico suggests that infected humans urinate or defecate in the water there (I don't normally think of Puerto Rico as having such poor sanitary conditions, but am I just wrong about that?). Could there be some other reason why schistosomiasis has persisted there, such as animals becoming infected which then urinate or defecate in the water to produce miracidia? I'm trying to assess the real risk that schistosomiasis could eventually become established in the US and I am wondering if there is really that much difference in human behavior between poor areas in the Southern US and Puerto Rico.

Dear John:

Schistosoma mansoni was prevalent in PR and the subject of study in the early 20th Cent. in the early 60- 70's there were programs to control the disease and in the 1980's with the advent of praziquantel to treat the infection and with improvements in sanitation, the parasites was eliminated. The snails may still be found there but the reservoir of infection has been eliminated, this doesn't mean that an infected persone cannot reintroduce the parasite, but it is unlikely. B. glabrata has not been recorded in the continental US (not Mexico as far as I know. There used to be an active team of researchers at Tulane, but by now they have all passed on or elsewhere, so we do not have active surveillance. However to address your final point, I think there is a huge difference in the sanitary conditions in both the South US and PR since the 1960's, so transmission of the parasite wont happen, but even so, there are no recorded species of Biomphalaria in the continental US, so no schistosomiasis can be transmitted here!

Clive, Thank you for your reply. This 2012 IAMAT document on shistosomiasis risk throughout the world (http://www.iamat.org/pdf/World_Schistosomiasis_Risk_Chart.pdf) makes it appear as though there are still infections taking place in Puerto Rico (apparently they haven't updated the status for Puerto Rico in a while). Thanks for the information.

There is at least one established B. glabrata population in Mississippi as I noted in an earlier post. It was only recently reported at a regional invasive species meeting (GSARP) . People had concerns that this new snail introduction could eventually lead to shistosomiasis disease in the area, so your comments help to put that risk into perspective.

Dear everyone:

My original post didn't state Biomphalaria was established in South FL.  I merely said Biomphalaria-type snails were present here and elsewhere in the southern US.  I didn't mean to imply members of the genus are here, but I think it likely they are.  Nearly everything else is here, from all over the world.  

The context of my original post was in reference to snails which are permissive intermediate hosts (not vectors!) for S. mansoni and Angiostrongylus spp.  The possibility isn't farfetched, either, since defecation or urination out of doors, difficult though it may be for some people to admit, is still fairly widespread in many places in the US.  

Moreover, the statement these parasites are or may be here isn't new information.  Angiostrongylus costaricensis was found in both southern Texas and Louisiana in the 1980s.  

Last, re: vectors, vectors are invertebrates that actively spread a disease,e such as a biting arthropod.  For both Schistosomes and Metastrongylids, however, the snail/slugs are Intermediate Hosts, not vectors, because the infectious stages of the parasites (cercariae in the former, L3 in the latter) are not actively being disseminated by these intermediate hosts activity but are passively shed as cercariae or L3 are in the organism that is consumed. JPCaruso PhD

Joseph, I read through all the comments and didn't notice a mention of "vector" so we are not at fault in nomenclature, however from all I have learned and know, I don't think any of the Planobidae have been incriminated in the Angiostrongylus cycle. This species uses terrestrial gastropods as intermediate hosts:

Dear Clive:

Copied from your original post of 4 June on this subject is the following phrase "Certainly there are pockets of Helisoma spp (the red spiral snail that is frequently kept in freshwater aquaria) but it is not a vector of schistosomes nor other trematodes."  I think this speaks for itself.  

Re: terrestrial gastropods as Angiostrongylus spp. intermediate hosts, this is certainly true these types of snails and slugs are the normal intermediate hosts for these infections.  However, it's also true we maintained both A. costaricensis and A. vasorum life cycles quite successfully in Biomphalaria glabrata and Biomphalaria pfeifferi at SMU and University of Georgia, respectively, when I worked with the two spp. in the 1970s and 1980s. 

Joe Caruso