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List of parasites of the marsh rice rat

A photograph of a red, eight-legged, oval-shaped organism with a white spot on its back standing on a green strip with a blue background
The lone star tick is one of the parasites that the marsh rice rat shares with other mammals.

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.[1] Some of these parasites are endoparasites, internal parasites, while others are ectoparasites, external parasites.[2]

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.[3] 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).[3] 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.[4] While the marsh rice rat harbors a number of host-specific species,[5] such as the nematode Aonchotheca forresteri, other parasite species, such as the lone star tick (pictured), are shared with other mammals.[6] Compared to the hispid cotton rat (Sigmodon hispidus), Florida marsh rice rats usually harbor fewer individual ectoparasites of each species.[7] 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.[8]


Name The 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 occurrence U.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.
Prevalence Prevalence 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.



The Acari include the mites and ticks. Many are parasites of other animals.[9] One study in South Carolina failed to find ticks on marsh rice rats living in marshes, which are an unsuitable habitat for the parasites.[10]

Name Geographic occurrence Prevalence Present on other species?
Amblyomma americanum Georgia[11] Yes[11]
Amblyomma maculatum South Carolina[12] Yes[12]
Androlaelaps casalis[13] Yes[13]
Androlaelaps fahrenholzi[Note 1] Florida;[14] Georgia[15] 50% (Everglades, Florida); 60% (Hillsborough Co., Florida);[14] 3/29 (southwestern Georgia)[16] Yes[17]
Dermacentor variabilis Florida;[18] Georgia;[16] Missouri;[19] South Carolina;[20] Tennessee[21] 47% (Everglades); 65% (Hillsborough Co.);[18] 12/29 (southwestern Georgia);[16] 21% (Chester Co., South Carolina)[12] Yes,[11] but marsh rice rat is among most important hosts[19]
Euschoengastia peromysci Georgia[22] Yes[22]
Euschoengastia setosa Georgia[22] No[22]
Euschoengastia sp. Georgia[23] No[23]
Eutrombicula batatas Florida[24] No[24]
Eutrombicula splendens Florida;[24] Georgia[16] 95% (Hillsborough Co.);[24] 1/29 (southwestern Georgia)[16] Yes[24]
Gigantolaelaps mattogrossensis[Note 2] Florida;[24] Georgia;[16] Texas[25] 35% (Everglades);[24] 14/29 (southwestern Georgia)[16] Yes, but in the United States occurs mainly in rice rats[16]
Haemogamasus, unidentified species Georgia[11]
Ixodes affinis Georgia[11] Yes[11]
Ixodes brunneus Georgia[23] Yes[23]
Ixodes cookei Virginia[26] Yes[26]
Ixodes minor South Carolina[12] Yes[12]
Ixodes scapularis Georgia;[11] North Carolina;[27] South Carolina;[28] Virginia[29] 30% (Outer Banks, North Carolina)[27] Yes[11]
Ixodes texanus Georgia[11] Yes[11]
Ixodes, unidentified species Florida[30]
Laelaps manguinhosi[Note 3] Florida; South Carolina; Texas[31] None north of Mexico[31]
Laelaps sp. Florida;[24] Georgia[16] 50% (Everglades); 10% (Hillsborough Co.);[24] 4/29 (southwestern Georgia)[16] Yes, but occurs mainly in rice rats[24]
Listrophoridae, unidentified species Florida;[18] Georgia[11]
Listrophorus, unidentified species Georgia[16] 8/29 (southwestern Georgia)[16]
Ornithonyssus bacoti[Note 4] Florida;[14] Georgia[16] 20% (Everglades); 50% (Hillsborough Co.);[14] 11/29 (southwestern Georgia)[16] Yes[14]
Ornithonyssus sp.[Note 5] Georgia[16] 1/29 (southwestern Georgia)[16] Yes[16]
Oryzomysia oryzomys[Note 6] Georgia[34] No[34]
Prolistrophorus bakeri[Note 7] Yes[36]
Prolistrophorus grassii[Note 8] Georgia[34] Yes[36]
Radfordia palustris[37] Florida; Georgia; South Carolina[37] No[37]


Sucking lice (Anoplura) are a diverse group infecting placental mammals.[38] Species found on marsh rice rats include three of the common genus Hoplopleura[39] and Polyplax spinulosa, which more usually infects black and brown rats.[40]

Name Geographic occurrence Prevalence Present in other species?
Hoplopleura hirsuta Georgia[16] 1/29 (southwestern Georgia)[16] Yes; usually occurs in cotton rats[41]
Hoplopleura oryzomydis[Note 9] Delaware; Florida;[42] Georgia;[22] Louisiana;[43] South Carolina;[42] Tennessee; Texas[43] 18% (Everglades); 35% (Hillsborough Co.);[30] 1/21 (Shelby County, Tennessee)[43] Yes[44]
Polyplax spinulosa Georgia;[16] Tennessee[40] 2/29 (southwestern Georgia)[16] Yes; normally infects Rattus[40]


Fleas (Siphonaptera) are common parasites of vertebrates, mainly mammals.[45] Several species of fleas have been found on the marsh rice rat.[46]

Name Geographic occurrence Prevalence Present in other species?
Ctenocephalides felis Georgia[22] Yes[22]
Ctenophthalmus pseudagyrtes Missouri;[47] Tennessee[48] 2/21 (Shelby Co., Tennessee)[48] Yes[47]
Epitedia wenmanni Missouri[47] Yes[47]
Polygenis gwyni Florida;[49] Georgia;[16] Mississippi;[50] South Carolina[51] 4/29 (southwestern Georgia);[16] 33% (Marion Co., Mississippi)[50] Yes; mainly found on the hispid cotton rat[51]
Stenoponia americana South Carolina;[52] Tennessee[53] 1/39 (Shelby Co.)[53] Yes[53]


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


Nematodes are among the largest animal phyla and include at least 12,000 known species that are parasites of vertebrates.[54] 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[55] and made up the bulk of the parasites found in rice rats there.[3]

Name Geographic occurrence Prevalence Present in other species?
Aonchotheca forresteri[Note 10] Florida 46% (Paynes Prairie, Florida); 1% (Cedar Key, Florida) No[58]
Capillaria gastrica Florida 4% (Paynes Prairie, Florida); 6% (Cedar Key, Florida) Yes[59]
Capillaria hepatica Florida 8% (Paynes Prairie, Florida); 6% (Cedar Key, Florida) Yes[60]
Hassalstrongylus forresteri Florida 92% (Paynes Prairie, Florida); 9% (Cedar Key, Florida)[Note 11] No[61]
Hassalstrongylus lichtenfelsi Florida No[61]
Hassalstrongylus musculi Florida Yes[61]
Litomosoides scotti Florida 57% (Cedar Key, Florida) No[62]
Mastophorus muris Georgia;[63] Florida[64] 36% (Paynes Prairie, Florida); 1% (Cedar Key, Florida) Yes[63]
Monodontus sp. Florida 1% (Cedar Key, Florida)
Parastrongylus schmidti[Note 12] Florida 7% (Paynes Prairie, Florida); 3% (Cedar Key, Florida) Not in the wild, but is able to infect other rodents in experiments[67]
Pterygodermatites ondatrae Florida 20% (Paynes Prairie, Florida); 5% (Cedar Key, Florida)[Note 13] Yes[64]
Pterygodermatites sp. Florida
Physaloptera hispida Florida 35% (Paynes Prairie, Florida) Yes[64]
Physaloptera sp. Florida 4% (Cedar Key, Florida)
Skrjabinoclava kinsellai[Note 14] Florida 28% (Cedar Key, Florida) No[68]
Spiruridae, unidentified larvae Florida 5% (Cedar Key, Florida)
Strongyloides sp. Florida 30% (Paynes Prairie, Florida)
Syphacia oryzomyos Florida 42% (Paynes Prairie, Florida) No[69]
Trichostrongylus affinis Florida 14% (Paynes Prairie, Florida); 6% (Cedar Key, Florida) Yes[64]
Trichostrongylus sigmodontis Florida 8% (Paynes Prairie, Florida); 3% (Cedar Key, Florida) Yes[64]


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.[55]

Name Geographic occurrence Prevalence Present in other species?
Hymenolepis diminuta Florida 19% (Paynes Prairie, Florida); 1% (Cedar Key, Florida) Yes[55]
Taenia rileyi Florida 1% (Cedar Key, Florida) Yes; usually infects bobcats[55]
Taenia mustelae Florida 0.5% (Paynes Prairie, Florida) Yes; usually infects skunks and mustelids[55]
Cladotaenia circi Florida 0.5% (Paynes Prairie, Florida); 1% (Cedar Key, Florida) Yes; usually infects hawks[55]


Flukes (Trematoda) from the subclass Digenea are common parasites of small mammals with complex life cycles.[70] 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.[3] Trematodes were generally more common at the Cedar Key saltwater marsh than at the freshwater marsh in Paynes Prairie.[55]

Name Geographic occurrence Prevalence Present in other species?
Acanthotrema cursitans[Note 15] Florida 52% (Cedar Key, Florida) Yes[72]
Ascocotyle angrense Florida 25% (Cedar Key, Florida) Yes; occurs mainly in birds[73]
Ascocotyle pindoramensis[Note 16] Florida 9% (Cedar Key, Florida) Yes; occurs mainly in birds[75]
Brachylaima virginianum[Note 17] Florida 15% (Paynes Prairie, Florida) Yes; occurs mainly in the Virginia opossum[76]
Catatropis johnstoni Florida 30% (Cedar Key, Florida) No other natural definitive host known, but occurs outside the range of the marsh rice rat and the normal host may be a bird[77]
Echinochasmus schwartzi Florida 19% (Cedar Key, Florida) Yes[78]
Fibricola lucida Florida 67% (Paynes Prairie, Florida); 11% (Cedar Key, Florida) Yes[79]
Gymnophalloides heardi[Note 18] Florida[80] 26% (Cedar Key, Florida) No[80]
Gynaecotyla adunca Florida 15% (Cedar Key, Florida) Yes; normally infects birds[81]
Levinseniella deblocki[Note 19] Florida[82] 49% (Cedar Key, Florida) Yes[82]
Lyperosomum intermedium Florida 45% (Cedar Key, Florida) No[83]
Maritrema heardi[Note 20] Florida[84] 19% (Cedar Key, Florida) No[86]
Maritrema prosthometra[Note 21] Florida 5% (Cedar Key, Florida) Yes[87]
Maritrema sp. I Florida 69% (Cedar Key, Florida) Yes[55]
Microphallus basodactylophallus Florida 94% (Cedar Key, Florida) Yes[88]
Microphallus nicolli Florida 9% (Cedar Key, Florida) Yes[89]
Microphallus sp. Florida 10% (Cedar Key, Florida) Yes[55]
Notocotylus fosteri Florida[90] 3/4 (Cedar Key, Florida)[90] No[90]
Odhneria odhneri Florida 6% (Cedar Key, Florida) Yes[91]
Probolocoryphe glandulosa Florida 56% (Cedar Key, Florida) Yes[88]
Urotrema scabridum Florida 23% (Cedar Key, Florida) Yes[92]
Zonorchis komareki Florida 1% (Cedar Key, Florida) Yes[93]


Pentastomida is an enigmatic group of parasites that may be related to maxillopod crustaceans.[94] One species, Porocephalus crotali, is known from the marsh rice rat.[95] It infects various mammals in the southeastern United States, which serve as intermediate hosts; snakes which eat those mammals are the definitive hosts.[96]

Name Geographic occurrence Prevalence Present in other species?
Porocephalus crotali Florida;[97] South Carolina[98] 12/105 (Levy County, Florida);[97] 3/17 (Bear Island, South Carolina)[98] Yes[97]


Apicomplexa is a major group of unicellular eukaryotes that encompasses several important parasites, including the malaria parasite Plasmodium.[99] Three species are known from the marsh rice rat,[95] all of which belong to the Eimerina clade.[100] Two are in the genus Eimeria, members of which cause the economically significant disease coccidiosis in poultry.[101] The third is a member of Isospora, which includes species that are pathogenic in humans and pigs.[102]

Name Geographic occurrence Prevalence Present in other species?
Eimeria kinsellai Florida[103] No[103]
Eimeria palustris Alabama[104] 7/19 (Tuskegee National Forest, Alabama)[105] No[105]
Isospora hammondi Alabama[104] 3/19 (Tuskegee National Forest, Alabama)[106] No[106]


  1. ^ Previously reported as Haemolaelaps glasgowi,[14] but that name is a synonym of Androlaelaps fahrenholzi.[13]
  2. ^ The Gigantolaelaps mite from the marsh rice rat was first described as Gigantolaelaps cricetidarum, a separate species, but later considered identical with G. mattogrossensis; some still consider the two to be different species.[25]
  3. ^ Laelaps oryzomydis is a synonym.[31]
  4. ^ Previously known as Bdellonyssus bacoti,[14] but since reassigned to Ornithonyssus.[32]
  5. ^ Originally assigned to Bdellonyssus (spelled Bdelonyssus),[16] but that name is a synonym of Ornithonyssus.[33]
  6. ^ Previously reported as Chilodiscoides oryzomys,[34] but now assigned to Oryzomysia.[35]
  7. ^ Previously known as Listrophorus bakeri,[34] but since assigned to the genus Prolistrophorus.[36]
  8. ^ Previously known as Listrophorus bakeri,[34] but since assigned to the genus Prolistrophorus.[36]
  9. ^ Listed as Hoplopleura quadridentata by Worth (1950),[30] but later described as a separate species, Hoplopleura oryzomydis.[42]
  10. ^ Originally placed in the genus Capillaria,[56] but later reassigned to Aonchotheca.[57]
  11. ^ Because females of these three species cannot be distinguished, data were combined.
  12. ^ Originally named Angiostrongylus schmidti by Kinsella (1971),[65] but moved to Parastrongylus by Ubelaker (1986).[66]
  13. ^ Females of these two species cannot be distinguished, so data were combined.
  14. ^ Listed as Skrjabinoclava thapari by Kinsella (1988),[4] but later described as a separate species.[68]
  15. ^ Listed as Stictodora cursitans by Kinsella (1988),[4] but moved to Acantothrema in 2003.[71]
  16. ^ Listed as Ascocotyle mollienisicola by Kinsella (1988), but that name is a synonym of A. pindoramensis.[74]
  17. ^ Spelled Brachylaeme by Kinsella (1988).
  18. ^ Reported as Parvatrema sp. by Kinsella (1988), but later described as Gymnophalloides heardi.[80]
  19. ^ Reported as Levinseniella sp. by Kinsella (1988), and described as L. deblocki in 1995.[82]
  20. ^ Reported as Maritrema sp. II by Kinsella (1988),[4] then described as the only member of its own genus, Floridatrema heardi,[84] and later again assigned to the genus Maritrema.[85]
  21. ^ This species was called prosthrometra by Kinsella (1988);[4] the correct spelling is prosthometra.[87]


  1. ^ Musser and Carleton, 2005, p. 1152; Wolfe, 1982, p. 1; Schmidt and Engstrom, 1994, p. 914
  2. ^ Wolfe, 1982, p. 3; Whitaker and Hamilton, 1998, p. 281
  3. ^ a b c d Kinsella, 1988, p. 278
  4. ^ a b c d e Kinsella, 1988, table 1
  5. ^ Kinsella, 1988, p. 275
  6. ^ Kinsella, 1988, p. 279
  7. ^ Worth, 1950, p. 334
  8. ^ Sonenshine et al., 1993, p. 10; Levin et al., 1993, p. 12
  9. ^ Borror and White, 1970, p. 52
  10. ^ Clark et al., 2001, p. 1382
  11. ^ a b c d e f g h i j k Wilson and Durden, 2003, table 1
  12. ^ a b c d e Clark et al., 2001, p. 1381
  13. ^ a b c Whitaker and Wilson, 1974, p. 4
  14. ^ a b c d e f g Worth, 1950, p. 329
  15. ^ Wilson and Durden, 2003, table 3
  16. ^ a b c d e f g h i j k l m n o p q r s t u v w x Morlan, 1952, table 2
  17. ^ Whitaker and Wilson, 1974, p. 5
  18. ^ a b c Worth, 1950, p. 331
  19. ^ a b Kollars et al., 2000, p. 640
  20. ^ Williams et al., 1999, p. 28
  21. ^ Kollars, 1996, p. 707
  22. ^ a b c d e f g Wilson and Durden, 2003, table 4
  23. ^ a b c d Wilson and Durden, 2003, table 2
  24. ^ a b c d e f g h i j Worth, 1950, p. 330
  25. ^ a b Carmichael et al., 2007, p. 80
  26. ^ a b Levine et al., 1991, p. 668
  27. ^ a b Levine et al., 1993, p. 8
  28. ^ Williams et al., 1999, p. 129
  29. ^ Sonenshine et al., 1993, p. 9
  30. ^ a b c Worth, 1950, p. 332
  31. ^ a b c Whitaker and Wilson, 1974, p. 10
  32. ^ Whitaker et al., 2007, pp. 27, 120; Radovsky, 2007, p. 223
  33. ^ Radovsky, 2007, p. 223
  34. ^ a b c d e f Whitaker and Wilson, 1974, p. 11
  35. ^ Whitaker et al., 2007, p. 5
  36. ^ a b c d Whitaker et al., 2007, p. 25
  37. ^ a b c Whitaker et al., 2007, p. 31
  38. ^ Durden and Musser, 1994, p. 1
  39. ^ Wolfe, 1982, p. 3; Pratt and Lane, 1951, p. 141
  40. ^ a b c Durden, 1988, p. 900
  41. ^ Durden and Musser, 1994, p. 27
  42. ^ a b c Pratt and Lane, 1951, p. 142
  43. ^ a b c Durden et al., 1997, p. 73
  44. ^ Durden and Musser, 1994, p. 31
  45. ^ Medvedev and Krasnov, 2006, p. 163
  46. ^ Wilson and Durden, 2003, table 4; Layne, 1971, p. 41
  47. ^ a b c d Kollars et al., 1997, table 1
  48. ^ a b Durden and Kollars, 1997, p. 15
  49. ^ Layne, 1971, p. 41
  50. ^ a b Clark and Durden, 2002, table 3
  51. ^ a b Durden et al., 1999, p. 176
  52. ^ Durden et al., 1999, p. 177
  53. ^ a b c Durden and Kollars, 1997, p. 17
  54. ^ Morand et al., 2006, p. 67
  55. ^ a b c d e f g h i Kinsella, 1988, p. 277
  56. ^ Kinsella and Pence, 1987, p. 1295
  57. ^ Pisanu and Bain, 1999, p. 21
  58. ^ Kinsella and Pence, 1987, p. 1297
  59. ^ Pulido-Flores et al., 2005, p. 191
  60. ^ Meagher, 1999, p. 1318
  61. ^ a b c Diaw, 1976, p. 1084
  62. ^ Forrester and Kinsella, 1973, p. 255
  63. ^ a b Doran, 1955, p. 164
  64. ^ a b c d e Kinsella, 1974, p. 7
  65. ^ Kinsella, 1971, p. 491
  66. ^ Ubelaker, 1986, p. 239
  67. ^ Robles et al., 2008, p. 517
  68. ^ a b Anderson and Wong, 1994, p. 1
  69. ^ Underwood et al., 1986, p. 411
  70. ^ Feliu et al., 2006, p. 13
  71. ^ Sohn et al., 2003, p. 157
  72. ^ Kinsella and Heard, 1974, p. 408
  73. ^ Núñez, 1993, p. 198
  74. ^ Simões et al., 2006, p. 501
  75. ^ Simões et al., 2006, p. 503
  76. ^ Foster et al., 2004, p. 174
  77. ^ Bush and Kinsella, 1972
  78. ^ Ditrich et al., 1996, p. 234
  79. ^ Kontrimavichus, 1985, p. 80
  80. ^ a b c Cheng, 1995, pp. 924, 926
  81. ^ Verberg and Hunter, 1961, p. 34
  82. ^ a b c Heard and Kinsella, 1995
  83. ^ Denton and Kinsella, 1972, p. 226
  84. ^ a b Kinsella and Deblock, 1995, p. 1
  85. ^ Tkach et al., 2005, p. 10
  86. ^ Kinsella and Deblock, 1994, p. 95; Kinsella, 1988, p. 277
  87. ^ a b Deblock and Heard, 1969, p. 416
  88. ^ a b Kinsella, 1974, pp. 5, 7
  89. ^ Mayer et al., 2003, p. 77
  90. ^ a b c Kinsella and Tkach, 2005, p. 195
  91. ^ Sinclair, 1971, p. 980
  92. ^ Goldberg et al., 1998, table 1
  93. ^ McKeever, 1971
  94. ^ Martin and Davis, 2001, p. 24
  95. ^ a b Wolfe, 1982, p. 3
  96. ^ Brookins et al., 2009, p. 460
  97. ^ a b c Forrester, 1992, p. 109
  98. ^ a b Forrester et al., 1970
  99. ^ Beck et al., 2009, p. 175
  100. ^ Beck et al., 2009, fig. 1
  101. ^ Beck et al., 2009, p. 177
  102. ^ Lindsay et al., 1997, p. 20
  103. ^ a b Barnard et al., 1971a, p. 546
  104. ^ a b Barnard et al., 1971b, p. 1293
  105. ^ a b Barnard et al., 1971b, p. 1294
  106. ^ a b Barnard et al., 1971b, p. 1295

Literature citedEdit