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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: bloodfluke planorb

Synonyms and Other Names: Planorbis glabratus Say 1818

Taxonomy: available through www.itis.gov

Identification: Snails in the family Planorbidae have a discoidal shape with a concave, flattened spire, and oblique aperture; adults have 5 to 6 whorls (Burch and Tottenham, 1980).

Size: Adult shells generally range from 15-30 mm in diameter, but can reach 40 mm (Barbosa et al., 1968).

Native Range: Neotropical species: West Indies (including Puerto Rico), Venezuela, Suriname, French Guiana, and Brazil (Barbosa et al., 1968).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Inhabits most any type of freshwater system of lakes, rivers and creeks, in addition to marshes, temporary ponds, and irrigation and drainage ditches (Barbosa et al., 1968).

Means of Introduction: It is not known how B. glabrata was introduced in the United States.

Status: Single collections have been reported from Florida (Burch and Tottenham 1980) and Idaho (Bowler and Frest 1991), but it is not known to be established in these states.  However, in North Carolina, collections of live specimens have been made at a single location over a three year period.  Museum specimens have yet to be located for collections mentioned in the Burch and Tottenham (1980) and Bowler and Frest (1991) publications.

Impact of Introduction: This snail is an obligatory host for the larval stage of the blood fluke trematode parasite Schistosoma mansoni which causes the disease Schistosomiasis in humans (Morgan et al., 2001). The parasite is found throughout Africa, Venezuela, parts of Brazil, and to a lesser degree in the Caribbean region (Centers for Disease Control and Prevention, 2014).  The parasite's endemic range is thought to be the Great Lakes region of central Africa (Schmidt and Rogers, 1981). The disease has not been found in the United States.

Remarks: These snails are hermaphroditic; they can either self- or cross-fertilize. In a laboratory setting, they become sexually mature as small as 7 mm in diameter in about 10 weeks and produce as many as six egg masses containing approximately 20 eggs (Pimentel, 1957). Larger, older snails produced up to 12 egg masses containing as many as 51 eggs, while averaging 28 eggs per mass (~10,000 eggs per year) (Pimentel, 1957). They can live two to three years in the laboratory, but probably one year in the wild (Pimentel, 1957).

References: (click for full references)

Barbosa, F.S., E.G. Berry, H.W. Harry, B. Hubendick, E.A. Malek, W.L. Paraense, E.C. Chamberlayne, and L.J. Olivier. 1968. A guide for identification of the snail intermmediate hosts of schistosomiasis in the Americas. Pan American Health Organization, Pan American Sanit. Bur., Washington, D.C., Sci. Publ. No. 168, pp. i-ix, 1-122.

Bowler, P.A., and T.J. Frest. 1991. The non-native snail fauna of the middle Snake River, southern Idaho. Proceedings of the Desert Fishes Council 23:28-44.

Burch, J.B., and J.L. Tottenham. 1980. North American freshwater snails: species list, ranges and illustrations. Walkerana - Transactions of the POETS Society 1(3):81-215.

Centers for Disease Control and Prevention. 2014. Parasites - Schistosomiasis, Epidemiology and Risk Factors. Online at http://www.cdc.gov/parasites/schistosomiasis/epi.html. Accessed 1/29/2014

Morgan, J.A., R.J. Dejong, S.D. Snyder, G.M. Mkoji, and E.S. Loker. 2001. Schistosoma mansoni and Biomphalaria: past history and future trends. Parasitology 123 Suppl.:S211-28.

Pimentel, D. 1957. Life history of Australorbis glabratus, the intermediate snail host of Schistosoma mansoni in Puerto Rico. Ecology 38(4):576-580.

Schmidt, G.D. and L.S. Roberts. 1981. Foundations of Parasitology. 2nd edition. The C.V. Mosby Company, St. Louis, MO.

Author: Benson, A.J.

Peer Review Date: 8/9/2019

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.