List of parasites of the marsh rice rat

A variety of parasites have been recorded from the marsh rice rat (Oryzomys palustris), a semiaquatic rodent found in the eastern and southern United States, north to New Jersey and Kansas and south to Florida and Texas, and in Tamaulipas, far northeastern Mexico.Musser and Carleton, 2005, p. 1152; Wolfe, 1982, p. 1; Schmidt and Engstrom, 1994, p. 914 Some of these parasites are endoparasites, internal parasites, while others are ectoparasites, external parasites.Wolfe, 1982, p. 3; Whitaker and Hamilton, 1998, p. 281

Parasitologist John Kinsella compared the endoparasites of marsh rice rats in a saltwater marsh at Cedar Key and a freshwater marsh at Paynes Prairie, both in Florida, in a 1988 study. He found a total of 45 species, a number unequaled in rodents. This may be related to the diverse habitats the rice rat uses and to its omnivorous diet; it eats a variety of animals which may serve as intermediate hosts of various parasites. The endoparasites in the saltwater marsh were dominated by trematodes (flukes), and those of the freshwater marsh by nematodes (roundworms). Endoparasites were found in the gastric mucosa (which lines the stomach), the cavity of the stomach, the small intestine, the cecum, the large intestine, the pancreatic duct, the bile ducts, the mucus of the liver, the pulmonary arteries, the abdominal cavity, and the pleural cavity.Kinsella, 1988, table 1 While the marsh rice rat harbors a number of host-specific species,Kinsella, 1988, p. 275 such as the nematode Aonchotheca forresteri, other parasite species, such as the lone star tick (pictured), are shared with other mammals.Kinsella, 1988, p. 279 Compared to the hispid cotton rat (Sigmodon hispidus), Florida marsh rice rats usually harbor fewer individual ectoparasites of each species.Worth, 1950, p. 334 Borrelia, the bacterium that causes Lyme disease, has been identified in some ticks that infect the marsh rice rat and it has been identified as a possible natural reservoir for Borrelia.Sonenshine et al., 1993, p. 10; Levin et al., 1993, p. 12

Key NameThe scientific name of the parasite species. A note is given where a species has been recorded on the marsh rice rat under different scientific names. Unnamed species are indicated with "sp." and parasites that could not be identified to species level are indicated with "unidentified".Geographic occurrenceU.S. states where the parasite has been recorded on the marsh rice rat (no parasite records are available from the Mexican distribution of the marsh rice rat). This information is unavailable for some parasites.PrevalencePrevalence of infection with the parasite in a studied marsh rice rat population. The prevalence is given either as a percentage (e.g., 10%) or as a fraction (e.g., 5/50, meaning that 5 out of 50 examined animals were infected with the parasite), together with the site of study. Prevalence figures are unavailable for some parasites.Present on other species?"Yes" indicates that the parasite has also been recorded on other host species, "no" that it is (as far as known) specific to the marsh rice rat. For some unnamed species, the sources do not indicate whether or not the species is specific to the marsh rice rat.

Ectoparasites Acari The Acari include the mites and ticks. Many are parasites of other animals.Borror and White, 1970, p. 52 One study in South Carolina failed to find ticks on marsh rice rats living in marshes, which are an unsuitable habitat for the parasites.Clark et al., 2001, p. 1382 Name Geographic occurrence Prevalence Present on other species? Amblyomma americanum GeorgiaWilson and Durden, 2003, table 1 – Yes Amblyomma maculatum South Carolina – Yes Androlaelaps casalisWhitaker and Wilson, 1974, p. 4 – – Yes Androlaelaps fahrenholzi Florida; GeorgiaWilson and Durden, 2003, table 3 50% (Everglades, Florida); 60% (Hillsborough Co., Florida); 3/29 (southwestern Georgia) YesWhitaker and Wilson, 1974, p. 5 Dermacentor variabilis Florida; Georgia; Missouri; South Carolina;Williams et al., 1999, p. 28 TennesseeKollars, 1996, p. 707 47% (Everglades); 65% (Hillsborough Co.); 12/29 (southwestern Georgia); 21% (Chester Co., South Carolina) Yes, but marsh rice rat is among most important hostsKollars et al., 2000, p. 640 Euschoengastia peromysci Georgia – Yes Euschoengastia setosa Georgia – No Euschoengastia sp. Georgia – No Eutrombicula batatas Florida – No Eutrombicula splendens Florida; Georgia 95% (Hillsborough Co.); 1/29 (southwestern Georgia) Yes Gigantolaelaps mattogrossensis Florida; Georgia; Texas 35% (Everglades); 14/29 (southwestern Georgia) Yes, but in the United States occurs mainly in rice rats Haemogamasus, unidentified species Georgia – – Ixodes affinis Georgia – Yes Ixodes brunneus GeorgiaWilson and Durden, 2003, table 2 – Yes Ixodes cookei VirginiaLevine et al., 1991, p. 668 – Yes Ixodes minor South CarolinaClark et al., 2001, p. 1381 – Yes Ixodes scapularis Georgia; North Carolina;Levine et al., 1993, p. 8 South Carolina;Williams et al., 1999, p. 129 VirginiaSonenshine et al., 1993, p. 9 30% (Outer Banks, North Carolina) Yes Ixodes texanus Georgia – Yes Ixodes, unidentified species FloridaWorth, 1950, p. 332 – – Laelaps manguinhosi Florida; South Carolina; Texas – None north of Mexico Laelaps sp. Florida;Worth, 1950, p. 330 Georgia 50% (Everglades); 10% (Hillsborough Co.); 4/29 (southwestern Georgia) Yes, but occurs mainly in rice rats Listrophoridae, unidentified species Florida;Worth, 1950, p. 331 Georgia – – Listrophorus, unidentified species Georgia 8/29 (southwestern Georgia) – Ornithonyssus bacoti Florida;Worth, 1950, p. 329 Georgia 20% (Everglades); 50% (Hillsborough Co.); 11/29 (southwestern Georgia) Yes Ornithonyssus sp. Georgia 1/29 (southwestern Georgia) Yes Oryzomysia oryzomys Georgia – No Prolistrophorus bakeri – – Yes Prolistrophorus grassii Georgia – Yes Radfordia palustrisWhitaker et al., 2007, p. 31 Florida; Georgia; South Carolina – No

Anoplura Sucking lice (Anoplura) are a diverse group infecting placental mammals.Durden and Musser, 1994, p. 1 Species found on marsh rice rats include three of the common genus HoplopleuraWolfe, 1982, p. 3; Pratt and Lane, 1951, p. 141 and Polyplax spinulosa, which more usually infects black and brown rats. Name Geographic occurrence Prevalence Present in other species? Hoplopleura hirsuta GeorgiaMorlan, 1952, table 2 1/29 (southwestern Georgia) Yes; usually occurs in cotton ratsDurden and Musser, 1994, p. 27 Hoplopleura oryzomydis Delaware; Florida;Pratt and Lane, 1951, p. 142 Georgia;Wilson and Durden, 2003, table 4 Louisiana; South Carolina; Tennessee; Texas 18% (Everglades); 35% (Hillsborough Co.); 1/21 (Shelby County, Tennessee)Durden et al., 1997, p. 73 YesDurden and Musser, 1994, p. 31 Polyplax spinulosa Georgia; Tennessee 2/29 (southwestern Georgia) Yes; normally infects RattusDurden, 1988, p. 900

Siphonaptera Fleas (Siphonaptera) are common parasites of vertebrates, mainly mammals.Medvedev and Krasnov, 2006, p. 163 Several species of fleas have been found on the marsh rice rat.Wilson and Durden, 2003, table 4; Layne, 1971, p. 41 Name Geographic occurrence Prevalence Present in other species? Ctenocephalides felis Georgia – Yes Ctenophthalmus pseudagyrtes Missouri;Kollars et al., 1997, table 1 TennesseeDurden and Kollars, 1997, p. 15 2/21 (Shelby Co., Tennessee) Yes Epitedia wenmanni Missouri – Yes Polygenis gwyni Florida;Layne, 1971, p. 41 Georgia; Mississippi; South CarolinaDurden et al., 1999, p. 176 4/29 (southwestern Georgia); 33% (Marion Co., Mississippi)Clark and Durden, 2002, table 3 Yes; mainly found on the hispid cotton rat Stenoponia americana South Carolina;Durden et al., 1999, p. 177 TennesseeDurden and Kollars, 1997, p. 17 1/39 (Shelby Co.) Yes

Endoparasites Unless otherwise specified, all information in this section is from Kinsella (1988, table 1).

Nematoda Nematodes are among the largest animal phyla and include at least 12,000 known species that are parasites of vertebrates.Morand et al., 2006, p. 67 In Kinsella's 1988 study in Florida, species diversity was higher in the saltwater marsh (Cedar Key) than the freshwater marsh (Paynes Prairie), but nematodes at Paynes Prairie occurred more commonly and made up the bulk of the parasites found in rice rats there. Name Geographic occurrence Prevalence Present in other species? Aonchotheca forresteri Florida 46% (Paynes Prairie, Florida); 1% (Cedar Key, Florida) NoKinsella and Pence, 1987, p. 1297 Capillaria gastrica Florida 4% (Paynes Prairie, Florida); 6% (Cedar Key, Florida) YesPulido-Flores et al., 2005, p. 191 Capillaria hepatica Florida 8% (Paynes Prairie, Florida); 6% (Cedar Key, Florida) YesMeagher, 1999, p. 1318 Hassalstrongylus forresteri Florida 92% (Paynes Prairie, Florida); 9% (Cedar Key, Florida) NoDiaw, 1976, p. 1084 Hassalstrongylus lichtenfelsi Florida No Hassalstrongylus musculi Florida Yes Litomosoides scotti Florida 57% (Cedar Key, Florida) NoForrester and Kinsella, 1973, p. 255 Mastophorus muris Georgia;Doran, 1955, p. 164 FloridaKinsella, 1974, p. 7 36% (Paynes Prairie, Florida); 1% (Cedar Key, Florida) Yes Monodontus sp. Florida 1% (Cedar Key, Florida) – Parastrongylus schmidti Florida 7% (Paynes Prairie, Florida); 3% (Cedar Key, Florida) Not in the wild, but is able to infect other rodents in experimentsRobles et al., 2008, p. 517 Pterygodermatites ondatrae Florida 20% (Paynes Prairie, Florida); 5% (Cedar Key, Florida) Yes Pterygodermatites sp. Florida – Physaloptera hispida Florida 35% (Paynes Prairie, Florida) Yes Physaloptera sp. Florida 4% (Cedar Key, Florida) – Skrjabinoclava kinsellai Florida 28% (Cedar Key, Florida) No Spiruridae, unidentified larvae Florida 5% (Cedar Key, Florida) – Strongyloides sp. Florida 30% (Paynes Prairie, Florida) – Syphacia oryzomyos Florida 42% (Paynes Prairie, Florida) NoUnderwood et al., 1986, p. 411 Trichostrongylus affinis Florida 14% (Paynes Prairie, Florida); 6% (Cedar Key, Florida) Yes Trichostrongylus sigmodontis Florida 8% (Paynes Prairie, Florida); 3% (Cedar Key, Florida) Yes

Cestoda Four tapeworms are known from the marsh rice rat, all in Florida, but three of those are usually found in other species and only rarely in the rice rat.Kinsella, 1988, p. 277 Name Geographic occurrence Prevalence Present in other species? Hymenolepis diminuta Florida 19% (Paynes Prairie, Florida); 1% (Cedar Key, Florida) Yes Taenia rileyi Florida 1% (Cedar Key, Florida) Yes; usually infects bobcats Taenia mustelae Florida 0.5% (Paynes Prairie, Florida) Yes; usually infects skunks and mustelids Cladotaenia circi Florida 0.5% (Paynes Prairie, Florida); 1% (Cedar Key, Florida) Yes; usually infects hawks

Digenea Flukes (Trematoda) from the subclass Digenea are common parasites of small mammals with complex life cycles.Feliu et al., 2006, p. 13 In his 1988 study, Kinsella found an unprecedented 21 species of trematodes in Florida marsh rice rats. The intermediate hosts of these trematodes include a variety of invertebrates, fish, and amphibians, which are eaten by the marsh rice rat.Kinsella, 1988, p. 278 Trematodes were generally more common at the Cedar Key saltwater marsh than at the freshwater marsh in Paynes Prairie.