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] |
Oryzomys is a genus of semiaquatic rodents in the tribe Oryzomyini living in southern North America and far northern South America. It includes eight species, two of which—the marsh rice rat (O. palustris) of the United States and O. couesi of Mexico and Central America—are widespread; the six others have more restricted distributions. The species have had eventful taxonomic histories, and most species were at one time included in the marsh rice rat; additional species may be recognized in the future. The name Oryzomys was established in 1857 by Spencer Fullerton Baird for the marsh rice rat and was soon applied to over a hundred species of American rodents. Subsequently, the genus gradually became more narrowly defined until its current contents were established in 2006, when ten new genera were established for species previously placed in Oryzomys.
The marsh rice rat is a semiaquatic North American rodent in the family Cricetidae. It usually occurs in wetland habitats, such as swamps and salt marshes. It is found mostly in the eastern and southern United States, from New Jersey and Kansas south to Florida and northeasternmost Tamaulipas, Mexico; its range previously extended further west and north, where it may have been a commensal in corn-cultivating communities. Weighing about 40 to 80 g, the marsh rice rat is a medium-sized rodent that resembles the common black and brown rat. The upperparts are generally gray-brown, but are reddish in many Florida populations. The feet show several specializations for life in the water. The skull is large and flattened, and is short at the front.
Maritrema heardi is a parasitic fluke that infects the marsh rice rat in a salt marsh at Cedar Key, Florida. It was first listed as Maritrema sp. II in 1988, then described as the only species of a new genus, Floridatrema heardi, in 1994, and eventually reassigned in 2003 to Maritrema as Maritrema heardi. Its intermediate host is the fiddler crab Uca pugilator and it lives in the intestine of the marsh rice rat, its definitive host. Together with two other species of Maritrema, it is very common in affected marsh rice rats; it infects 19% of studied rats at Cedar Key. According to Tkach and colleagues, M. heardi is probably primarily a parasite of birds that has secondarily infected the marsh rice rat. Floridatrema was distinguished from Maritrema on the basis of its possession of loops of the uterus that extend forward to the place where the intestine is forked or even to the pharynx. Genetically, M. heardi may be closest to the morphologically similar M. neomi, which infects Neomys water shrews in the Carpathians.
Gigantolaelaps mattogrossensis is a mite from the Americas. It has been found on the marsh rice rat, hispid cotton rat, black rat, brown rat, and white-footed mouse in the United States. In Venezuela, it has been recorded from Holochilus brasiliensis, Sigmodon hirsutus, and Marmosa robinsoni. In Argentina, it has been found on Scapteromys aquaticus, Oligoryzomys flavescens, and Holochilus brasiliensis. The North American form was first described as a separate species, Gigantolaelaps cricetidarum, and is still occasionally considered as such.
Ascocotyle pindoramensis is a fluke in the genus Ascocotyle that occurs along the eastern coast of the Americas from Brazil to Nicaragua, Mexico, Louisiana, and Florida and doubtfully in Egypt. It occurs in the intestine of its definitive hosts. Hosts recorded in the wild include the least bittern, roseate spoonbill, great blue heron, striated heron, stripe-backed bittern, yellow-crowned night heron, black-crowned night heron, osprey, Neotropic cormorant, and marsh rice rat. In the marsh rice rat, it infected 9% of rats examined in a 1970–1972 study in the salt marsh at Cedar Key, Florida, but none in a freshwater marsh. A. pindoramensis has been experimentally introduced into the domestic duck, chicken, dog, house mouse, and golden hamster. It occurs in various body parts of its intermediate hosts—the poeciliid fish Phalloptychus januarius, Poecilia catemaconis, Poecilia mexicana, Poecilia mollienisicola, Poecilia vivipara, and a species of Xiphophorus and the cichlid Tilapia. It was first described as Pygidiopsis pindoramensis in 1928 and subsequently as Pseudoascocotyle mollienisicola in 1960. The latter species was moved to Ascocotyle in 1963, but only in 2006 it was recognized that the two represent the same species, which is now known as Ascocotyle pindoramensis. Other flukes from Argentina and Mexico that were identified as Pygidiopsis pindoramensis instead represent a different species of Pygidiopsis.
Catatropis johnstoni is a fluke from the United States. It was first described in 1956 by Martin, who had found cercariae released by the snail Cerithidea californica in southwestern California. When the cercaria were fed into chickens, they developed into mature worms; Martin speculated that the natural host was a waterbird. In 1970, a study of helminths of the marsh rice rat in a saltmarsh at Cedar Key, Florida, found flukes similar to C. johnstoni. The fluke was present in 30% of 110 examined rice rats, with the number of worms per rat varying from 1 to 500. Some Cerithidea scalariformis snails from this marsh also released cercariae similar to C. johnstoni from California. When introduced into chickens, marsh rice rats, Mongolian gerbils, golden hamsters, and house mice, these cercariae developed into infectious flukes. Bush and Kinsella, who reported on the result in 1972, regarded the Florida and California flukes as the same species, as there were only minor size differences between them. Because no marsh-inhabiting rodent occurs in both California and Florida, they agreed with Martin that the normal host of C. johnstoni was most likely a bird, perhaps a rail or shorebird. Nevertheless, the rate of infection in the rice rat is too high for it to be just an accidental host; perhaps C. johnstoni is restricted to saltmarshes but not host-specific.
Ctenophthalmus pseudagyrtes is a species of fleas in the family Hystrichopsyllidae. It is widespread in North America, east of the Rocky Mountains, and is found mainly on small mammals. In Missouri, it has been recorded on the Virginia opossum, northern short-tailed shrew, eastern mole, raccoon, eastern chipmunk, Florida woodrat, prairie vole, woodland vole, white-footed mouse, including nests, marsh rice rat, hispid cotton rat, house mouse, and brown rat. Hosts recorded in Tennessee include the Virginia opossum, northern short-tailed shrew, eastern mole, eastern chipmunk, southern red-backed vole, rock vole, woodland vole, white-footed mouse, golden mouse, hispid cotton rat, marsh rice rat, and house mouse.
Maritrema is a genus of trematodes (flukes) in the family Microphallidae, although some have suggested its placement in the separate family Maritrematidae. It was first described by Nikoll in 1907 from birds in Britain. Species of the genus usually infect birds, but several have switched hosts and are found in mammals, such as the marsh rice rat. Several species use the fiddler crab Uca pugilator as an intermediate host.
Odhneria odhneri is a digenean parasite in the genus Odhneria of family Microphallidae. It infects several species of shorebirds, including the willet, as well as the marsh rice rat.
Acanthotrema cursitans is a species of fluke in the genus Acanthotrema. It infects the marsh rice rat Oryzomys palustris, the raccoon Procyon lotor, the Virginia opossum Didelphis virginiana, the snail Cerithidea scalariformis, and killifishes of the genus Fundulus on the Gulf Coast of Florida. It was first described as Cercaria cursitans in 1961, then moved to Stictodora in 1974, and to Acanthotrema in 2003.
Monodontus is a genus of parasitic nematodes in the subfamily Bunostominae of family Ancylostomatidae. Most of its species occur in rodents and suids, but Monodontus louisianensis is from the white-tailed deer and Monodontus giraffae from the giraffe. An unspecified Monodontus has been recorded from the marsh rice rat in Florida.
Amblyomma maculatum is a species of tick in the genus Amblyomma. Immatures usually infest small mammals and birds that dwell on the ground; cotton rats may be particularly favored hosts. Some recorded hosts include:
Haemogamasus is a genus of mites in the family Haemogamasidae. In North America, they mostly infect rodents, in addition to other small mammals such as shrews, talpids, and Virginia opossums.
Listrophorus is a genus of parasitic mites in the family Listrophoridae. North American species with their hosts include:
Listrophoridae is a family of mites in the suborder Psoroptidia of the order Sarcoptiformes. The family contains small, long mites specialized for grasping the hairs of mammals. North American genera include:
Oryzomysia oryzomys is a parasitic mite in the genus Oryzomysia of the family Atopomelidae. It has been found on the marsh rice rat in Georgia. It was formerly known as Chirodiscoides oryzomys in the family Listrophoridae, but was later transferred to the atopomelid genus Oryzomysia.
Prolistrophorus bakeri is a parasitic mite in the genus Prolistrophorus. Together with the Argentine P. hirstianus, it forms the subgenus Beprolistrophorus. P. bakeri has been found on the hispid cotton rat, marsh rice rat, and cotton mouse in Georgia, South Carolina, Texas, and Florida and on Oryzomys couesi in Colima. It was formerly placed in the genus Listrophorus.
Radfordia palustris is a species of mite in the subgenus Hesperomyobia of the genus Radfordia. It has been recorded on the marsh rice rat in Florida, Georgia, and South Carolina.
Physaloptera is a genus of parasitic nematodes in the family Physalopteridae.
Laelaps is a genus of common parasitic mites in the family Laelapidae. Species, with their hosts, include: