Analyses of Bloodmeal Hosts and Prevalence of Rickettsia parkeri in the Gulf Coast Tick Amblyomma maculatum (Acari: Ixodidae) From a Reconstructed Piedmont Prairie Ecosystem, North Carolina.

Host feeding patterns and the prevalence of infection with Rickettsia parkeri were determined for the primary vector, Amblyomma maculatum Koch as well as sympatric tick species A. americanum (Linnaeus) and Dermacentor variabilis (Say) collected from a reconstructed prairie in the Piedmont region of North Carolina during 2011 and 2012. The occurrence of R. parkeri among A. maculatum adults and nymphs was 36.9% (45/122) and 33.3% (2/6), respectively. Rickettsia parkeri was detected in a single male A. americanum 2.3% (1/43). A PCR-reverse line blot hybridization assay of a 12S rDNA fragment amplified from remnant larval and nymphal bloodmeals of host-seeking ticks was used to identify bloodmeal hosts. Of the tick samples tested, bloodmeal host identification was successful for 29.3% (12/41) of adult A. americanum and 39.2% (20/51) of adult D. variabilis. For A. maculatum, bloodmeal host identification was successful for 50% (61/122) of adults collected from vegetation and 100% (4/4) of nymphs removed from cotton rats (Sigmodon hispidus Say and Ord). The cotton rat was the most common bloodmeal host with 59.0% (36/61) identified for adult A. maculatum. No statistically significant association was observed, however, between bloodmeal host and pathogen prevalence for any tick species. While the cotton rat was an important bloodmeal host for A. maculatum nymphs, this vertebrate did not appear to be the primary source of R. parkeri infection for A. maculatum.

Emerging hantaviruses in Central Argentina: First case of Hantavirus Pulmonary Syndrome caused by Alto Paraguay virus, and a novel orthohantavirus in Scapteromys aquaticus rodent.

Orthohantaviruses are emerging rodent-borne pathogens that cause Hantavirus Pulmonary Syndrome in humans. They have a wide range of rodent reservoir hosts and are transmitted to humans through aerosolized viral particles generated by the excretions of infected individuals. Since the first description of HPS in Argentina, new hantaviruses have been reported throughout the country, most of which are pathogenic to humans. We present here the first HPS case infected with Alto Paraguay virus reported in Argentina. Until now, Alto Paraguay virus was considered a non-pathogenic orthohantavirus since it was identified in a rodent, Holochilus chacarius. In addition to this, with the goal of identifying potential hantavirus host species in the province of Santa Fe, we finally describe a novel orthohantavirus found in the native rodent Scapteromys aquaticus, which differed from other hantaviruses described in the country so far. Our findings implicate an epidemiological warning regarding these new orthohantaviruses circulating in Central Argentina as well as new rodent species that must be considered as hosts from now on.

Molecular bloodmeal analyses reveal that Trypanosoma cruzi-infected, native triatomine bugs often feed on humans in houses in central Brazil.

The identification of bloodmeal sources in triatomine bugs (Hemiptera: Reduviidae) is important in understanding vector-host associations and in measuring the risk for Chagas' disease transmission. The bloodmeal sources of triatomines infected with Trypanosoma cruzi (Trypanosomatida: Trypanosomatidae) caught in houses in central Brazil (Goiás State and the Federal District) were investigated during 2012-2014. Mitochondrial cytochrome b amplicons were used to identify bloodmeals through high-resolution melting and DNA sequencing. Most bugs were found to have fed on either humans (45.7%) or chickens (43.1%). Human blood was detected in Triatoma sordida (n = 22/50 bugs), Triatoma pseudomaculata (n = 7/11 bugs), Panstrongylus megistus (n = 10/24 bugs), Panstrongylus geniculatus (n = 1/3 bugs) and Rhodnius neglectus (n = 18/28 bugs) (all: Hemiptera: Reduviidae). Sequencing identified Necromys (Rodentia: Cricetidae) mouse blood in P. geniculatus and Tropidurus (Squamata: Tropiduridae) lizard blood in T. pseudomaculata and T. sordida. These findings reveal new vector-host associations. The present results suggest frequent contact between humans and T. cruzi-infected triatomines in central Brazil and indicate that Chagas' disease transmission by native vectors is an ongoing threat.

Mammal decline, linked to invasive Burmese python, shifts host use of vector mosquito towards reservoir hosts of a zoonotic disease.

Invasive apex predators have profound impacts on natural communities, yet the consequences of these impacts on the transmission of zoonotic pathogens are unexplored. Collapse of large- and medium-sized mammal populations in the Florida Everglades has been linked to the invasive Burmese python, Python bivittatus Kuhl. We used historic and current data to investigate potential impacts of these community effects on contact between the reservoir hosts (certain rodents) and vectors of Everglades virus, a zoonotic mosquito-borne pathogen that circulates in southern Florida. The percentage of blood meals taken from the primary reservoir host, the hispid cotton rat, Sigmodon hispidus Say and Ord, increased dramatically (422.2%) from 1979 (14.7%) to 2016 (76.8%), while blood meals from deer, raccoons and opossums decreased by 98.2%, reflecting precipitous declines in relative abundance of these larger mammals, attributed to python predation. Overall species diversity of hosts detected in Culex cedecei blood meals from the Everglades declined by 40.2% over the same period (H(1979) = 1.68, H(2016) = 1.01). Predictions based upon the dilution effect theory suggest that increased relative feedings upon reservoir hosts translate into increased abundance of infectious vectors, and a corresponding upsurge of Everglades virus occurrence and risk of human exposure, although this was not tested in the current study. This work constitutes the first indication that an invasive predator can increase contact between vectors and reservoirs of a human pathogen and highlights unrecognized indirect impacts of invasive predators.

Alterations triggered by steroid gonadal hormones in triglycerides and the cellular immune response of Calomys callosus infected with the Y strain of Trypanosoma cruzi.

Calomys callosus is a wild rodent found naturally infected with different Trypanosoma cruzi strains. In the work described here, groups of male and female C. callosus were subjected to orchiectomy, ovariectomy and sham operation. One month after surgery, animals were inoculated intraperitoneally (i.p.) with 4x10(4) blood trypomastigotes of the "Y" strain of T. cruzi. Parasitemia, triglycerides, nitric oxide (NO) and concanavalin A (ConA)-induced proliferation were evaluated. Parasitemia during the course of infection was significantly higher in infected and sham operated animals as compared to infected orchiectomized animals. The opposite was observed in the ovariectomized and infected group. Orchiectomized and infected animals displayed elevated triglyceride levels, as well as a more vigorous immune response, with higher splenocyte proliferation and elevated concentrations of NO. Ovariectomy resulted in an impaired immune response, as observed by a reduction of splenocyte proliferation and NO concentration. The results suggest a pivotal role for gonadal hormones in the modulation of triglyceride levels and the magnitude of the immune response during the acute phase of T. cruzi infection.

[Trypanosomatidae of public health importance occurring in wild and synanthropic animals of rural Venezuela]. / Trypanosomatidae de importancia en salud pública en animales silvestres y sinantrópicos en un area rural del municipio Tovar del estado Mérida, Venezuela.

INTRODUCTION: Chagas disease and leishmaniasis are important public health problems due to their high frequency and broad distribution in Latin America. Understanding of the roles of reservoir animals is crucial for a global assessment of the epidemiology of these diseases. OBJECTIVE: To identify parasites classed as Trypanosomatidae as they occurred in sylvatic animals, and to establish rates of coinfection. MATERIALS AND METHODS: Sylvatic animals were systematically captured in the rural area of El Carrizal, Merida State, Venezuela, betweenJuly, 1998 and February, 2000. The captures were made in Tomahawk type homemade traps, placed 15 nights per month throughout the study period. Blood was extracted from each captured and anesthetized animal by means of cardiac puncture. The search for trypanosomatids was undertaken by fresh blood examination, Giemsa stained blood smears and by means of blood-agar culture. Occasional xenodiagnoses were made to check diagnostic accuracy. The isolates obtained in culture media were identified by restriction fragment analysis and hybridization with specific probes. RESULTS: Three species of sylvatic animals (n = 215) were captured: Rattus spp. (135), Sigmodon hispidus (73) and Didelphis marsupialis (7). From them, three species of Trypanosomatidae were identified: Leishmania (Viannia) guyanensis, Trypanosoma cruzi and Trypanosoma lewisi. Trypanosoma. cruzi was identified in D. marsupialis (4/7), S. hispidus (1/73) and Rattus spp. (1/ 135), whereas L. (V.) guyanensis and T. lewisi were identified only in Rattus spp., 1/135 and 12/ 135, respectively. CONCLUSIONS: The coexistence of these genetically related hemoflagellates in sylvatic hosts was important for understanding the immunological interactions that may be established in reservoir animals, and the possible implications that this may have for the susceptible host. Finally, the identification of L. (V.) guyanensis in Rattus spp and T. cruzi in S. hispidus constituted the first reports of this relationship in Venezuela.

[First serological evidence of Hantavirus infection in rodents in Colombia]. / Primera evidencia serológica de infección por Hantavirus en roedores, en Colombia.

OBJECTIVE: Determining Hantavirus infection prevalence in rodents in the C6rdoba department, Colombia. METHODS: Rodents were captured using Sherman live-capture traps (8 x 9 x 23 cm; Sherman Traps, Inc., Tallahassee, FL) in peridomestic areas of Córdoba. Hantavirus IgG antibodies were detected by ELISA using Sin Nombre virus (SNV) recombinant nucleocapsid antigen (CDC, Atlanta, Georgia, USA). RESULTS: 336 rodents were captured in 11 townships in the Córdoba department (Murinae: 249; Sigmodontinae: 68; Heteromyidae: 17; Echimyidae: 2; 8.5% overall trap success) during 79 nights of trapping between January 2003 and November 2004. Hantavirus antibody seroprevalence was 2.1% (7 out of 336 captures). Prevalence by genus varied between 5.9% (1 out of 17 Heteromys) to 50% (1 out of 2 Proechimys). CONCLUSIONS: SNV-reactive antibody prevalence in rodents in Córdoba, Colombia, indicated that at least one hantavirus is endemic in rodents in northern Colombia and is frequently transmitted to rural residents.

Primera evidencia serológica de infección por Hantavirus en roedores, en Colombia / First serological evidence of Hantavirus infection in rodents in Colombia

OBJETIVO: Determinar la prevalencia de infección por hantavirus en roedores del Departamento de Córdoba, Colombia. METODOLOGIA: Captura de roedores con trampas tipo Sherman live-capture traps (8x9x23 cm; Sherman Traps, Inc., Tallahassee, FL) en áreas domésticas y peridomésticas en el departamento de Córdoba. Analisis de anticuerpos IgG por ELISA, empleando como antígeno una proteína recombinante de la nucleocapside del Sin Nombre Virus (SNV) (CDC, Atlanta, Georgia, USA). RESULTADOS: Durante los meses de enero de 2003 a noviembre de 2004, en 79 noches de trampeo fueron capturados 336 roedores en once municipios del departamento de Córdoba (Murinae: 249; Sigmodontinae: 68; Heteromyidae: 17; Echimyidae: 2) (éxito de captura del 8,5 por ciento). La seroprevalencia de anticuerpos contra hantavirus fue del 2,1 por ciento (7 de 336 capturas). Los porcentajes de seropositividad específicos por género oscilaron entre 5,9 por ciento (1 de 17, Heteromys) a 50 por ciento (1 de 2, Proechimys). CONCLUSIONES: La prevalencia de anticuerpos contra el SNV en roedores de Córdoba, Colombia; indica que al menos un hantavirus es endémico en roedores del norte colombiano y esta frecuentemente trasmitido a residentes rurales.

Immune function and hematology of male cotton rats (Sigmodon hispidus) in response to food supplementation and methionine.

We examined effects of supplementation of food quantity and quality (=enhanced methionine) on hematologic and immunologic parameters of wild, but enclosed, adult male cotton rats (Sigmodon hispidus) in north-central Oklahoma. Sheet metal enclosures were stocked with a high density of wild-caught cotton rats (160 animals/ha) and randomly assigned a treatment of no supplementation, mixed-ration supplementation or methionine-enhanced supplementation. Aside from small increases in counts of red blood cells and hematocrit levels, most indices of erythrocytic characteristics were not affected by supplementation with the mixed-ration or enhanced methionine. In contrast, platelet counts were highest in mixed-ration and methionine treatments and counts of total white blood cells were highest with methionine supplementation, albeit relative proportions of different leukocytes did not differ among treatments. Immunologically, neither delayed-type hypersensitivity response nor hemolytic-complement activity differed among treatments. Supplementation of food quantity and quality did not broadly affect hematologic parameters and immune function of male cotton rats, but enhanced platelet and leukocyte counts may confer advantages to overall health. Clarification of the role of such effects on population limitation or regulation requires additional research.

Elimination of plant toxins by herbivorous woodrats: revisiting an explanation for dietary specialization in mammalian herbivores.

Constraints on rates of detoxification and elimination of plant toxins are thought to be responsible for limiting dietary specialization in mammalian herbivores. This hypothesis, known as the detoxification limitations hypothesis, suggests that most mammalian herbivores are generalists to avoid overdosing on toxins from a single plant species. The hypothesis also predicts that the few mammalian specialists that exist should have adaptations for rapid detoxification and elimination of plant secondary compounds. We took a pharmacological approach to test whether specialists eliminate toxins from the bloodstream faster than generalists. We compared elimination rate and total exposure of alpha-pinene in closely related dietary specialist and generalist woodrats, Neotoma stephensi and N. albigula, respectively. Animals were orally gavaged with alpha-pinene, a plant secondary compound present in the natural diets of both woodrat species. We collected venous blood at 3, 6, 10, 15, and 20 min post-ingestion of alpha-pinene. Blood was analyzed for alpha-pinene concentration using gas chromatography. We found that specialist and generalist woodrats did not differ in elimination rates of alpha-pinene. However, specialists had lower exposure levels of alpha-pinene than generalists due to lower initial delivery of alpha-pinene to the general circulation. The levels of alpha-pinene detected in the bloodstream of specialists were 4.7-5.3x lower over all time intervals than generalists. Thus, specialists encounter a functionally lower dose of toxin than generalists. We suggest that the lower exposure level of specialist woodrats may be due to mechanisms in the gut that decrease toxin absorption. Regardless of mechanism, lower exposure to plant toxins may allow specialists to forage on diets with high toxin concentrations thereby facilitating dietary specialization.

Ecotoxicological risks associated with land treatment of petrochemical wastes. III. Immune function and hematology of cotton rats.

Landfarming is a widely used method of treating petrochemical waste through microbial bio-degradation. The effects of residual petrochemical contamination on wildlife, especially terrestrial mammals, are poorly understood. The effects of contaminants on the immune system and hematology of cotton rats (Sigmodon hispidus) living on five abandoned petrochemical landfarms (units 1-5) in Oklahoma were studied. Cotton rats were sampled seasonally (summer and winter) from each landfarm and from five ecologically matched reference sites for 2 yr (1998-2000) and returned to the laboratory for immunological and hematological assays. Overall analysis indicated that rats inhabiting landfarms exhibited decreased relative spleen size compared to rats collected from reference sites, with the landfarm at unit 1 showing the greatest reduction. Cotton rats collected from landfarms also had increased hemoglobin, hematocrit, and platelet levels and decreased blood leukocytes during summer. During winter, an increase in the number of popliteal node white blood cells was observed from rats collected on landfarms. No marked difference was detected for lymphocyte proliferation in response to concanavalin A, pokeweed, or interleukin-2. Lymphokine-activated killer cell lytic ability showed a seasonal pattern, but no treatment differences. No differences between landfarm and reference sites were detected in the hypersensitivity reaction of rats given an intradermal injection of phytohemagluttinin (PHA-P). Comparisons within individual sites indicated that two sites (units 1 and 3) had the greatest effects on immune function and hematology of cotton rats. The results of this study suggest that residual petrochemical waste affects the immune system and hematology of cotton rats living on abandoned landfarms during summer and is complicated by variation in the contaminants found on individual petroleum sites.

Hematology and serum biochemistry values of dusky-footed wood rat (Neotoma fuscipes).

Serum chemistry values and complete blood counts were determined for 36 wild dusky-footed wood rats (Neotoma fuscipes) from Sonoma and western Yolo County, California (USA) in summer 1999 and spring 2001. All wood rats had adequate body condition and were hydrated. Many hematologic and biochemical values were comparable to those for house rat (Rattus rattus). There were differences between wood rats tested immediately after capture (those from Yolo County) and after a week of habituation in the laboratory (Sonoma County). Significant differences were noted in red blood cell counts, hemoglobin, hematocrit, neutrophil:lymphocyte ratio, glucose, alanine transaminase, aspartate aminotransferase, and alkaline phosphatase values. The neutrophil:lymphocyte ratio may have been iatrogenically modified in the wood rats tested immediately after capture by stress-induced neutrophilia and lymphopenia. Eosinophilia may have been associated with parasites such as botflies in four individuals, and hyperglycemia in three individuals could have been associated with stress. The cause of elevated enzymes in the animals tested after laboratory habituation is unclear. The hematologic and biochemical values of these apparently healthy wood rats provide valuable baseline information for use in further medical studies performed with this species.

Persistent infection in Neotoma fuscipes (Muridae: Sigmodontinae) with Ehrlichia phagocytophila sensu lato.

Dusky-footed wood rats (Neotoma fuscipes Baird) and two species of Peromyscus mice (P. maniculatus Wagner and P. truei Shufeldt) were collected over a 16-month period from three sites in Sonoma County, California. Blood was collected from 93 wood rats and 177 mice and serum or plasma was tested for seroreactivity with Ehrlichia phagocytophila sensu lato (also known as the human granulocytic ehrlichiosis agent). Thirty-five (37.6%) wood rats and 15 (8.5%) mice were seropositive. Positive Neotoma serology by site ranged from 9.4% to 62.1%. Polymerase chain reaction (PCR) testing for the Ehrlichia groESL heat shock operon was performed on all the seropositive and selected seronegative wood rats; 24 (68.6%) seropositive animals were PCR positive. Two seroconversions and no seroreversions were detected among 18 of the seropositive wood rats that were recaptured and tested multiple times (range = 2-6). Fourteen (77.8%) of the 18 were also PCR positive with six of these positive at every testing point (range = 2-6). One wood rat remained serologically and PCR positive in six specimens collected over a 14-month period. One male of 84 questing adult Ixodes pacificus Cooley & Kohls collected was PCR-positive for E. phagocytophila. Borrelia burgdorferi, the agent of Lyme disease, was cultured from ear punch biopsies from six of seven E. phagocytophila seropositive and one of four seronegative wood rats.

Recombinant bovine adenovirus type 3 expressing bovine viral diarrhea virus glycoprotein E2 induces an immune response in cotton rats.

Recombinant bovine adenovirus is being developed as a live vector for animal vaccination and for human gene therapy. In this study, two replication-competent bovine adenovirus 3 (BAV-3) recombinants (BAV331 and BAV338) expressing bovine viral diarrhea virus (BVDV) glycoprotein E2 in the early region 3 (E3) of BAV-3 were constructed. Recombinant BAV331 contains chemically synthesized E2 gene (nucleotides modified to remove internal cryptic splice sites) under the control of BAV-3 E3/major late promoter (MLP), while recombinant BAV338 contains original E2 gene under the control of human cytomegalovirus immediate early promoter. Since E2, a class I membrane glycoprotein, does not contain its own signal peptide sequence at the 5' end, the bovine herpesvirus 1 (BHV-1) glycoprotein D signal sequence was fused in frame to the E2 open reading frame (ORF) for proper processing of the E2 glycoprotein in both the recombinant viruses. Recombinant E2 protein expressed by BAV331 and BAV338 recombinant viruses was recognized by E2-specific monoclonal antibodies as a 53-kDa protein, which also formed dimer with an apparent molecular weight of 94 kDa. Insertion of an E2-expression cassette in the E3 region did not effect the replication of recombinant BAV-3s. Intranasal immunization of cotton rats with these recombinant viruses generated E2-specific IgA and IgG responses at the mucosal surfaces and in the serum. In summary, these results show that the pestivirus glycoprotein can be expressed efficiently by BAV-3. In addition, mucosal immunization with replication-competent recombinant bovine adenovirus 3 can induce a specific immune response against the expressed antigen.

Incidencia de la infección por virus pirital en roedores de la especie sigmodón alstoni: efectos de la infección sobre la especie / Incidence of the pirital virus infection in rodents of the sigmodon alstony species: effects of the infection on the specie

El virus Pirital es un nuevo arenavirus descubierto en Venezuela, sin embargo no existen evidencias de que pueda ser un virus patógeno para el humano. Sus efectos en el roedor que le sirve de reservorio natural: sigmodón alstoni se analiza en el presente estudio. Un total de 478 roedores: S. alstoni fueron capturados entre junio de 1994 a diciembre de 1995 en el Municipio Papelón, estado Portuguesa. Se recolectaron muestras de sangre y bazo para el aislamineto e identificación de virus en cultivo de células Vero E6. La densidad de la población de roedores S. alstoni mostró un patrón estacional con un máximo éxito de trampeo al final de la estación de sequía (Marzo-Abril). Esta variación temporal no estuvo correlacionada con variaciones en la prevalencia de infección por virus Pirital. El promedio de infección en la especie fue de 33,8 por ciento con un incremento no significativo en la prevalencia de infección entre animales juveniles y adultos. El efecto de la infección por el virus Pirital en el peso y tamaño del cuerpo de los roedores así como en la fertilidad, número de animales por camada, etc. no fue significativamente diferente cuando se compararon los animales infectados con los no infectados

Environmental, age, and sex effects on cotton rat (Sigmodon hispidus) hematology.

We determined the effects of sex, age, and environment (inbred, captive-wild, and wild animals) on selected blood parameters of the cotton rat (Sigmodon hispidus) in central Oklahoma (USA) from 1990 to 1994. Male and female cotton rats had similar blood profiles. Age-related differences were confined to differential white blood cell counts where adults possessed greater numbers of neutrophils and lower numbers of lymphocytes compared to juveniles. Environment had a strong influence on many hematological parameters. Hematocrit, hemoglobin concentration, RBC count, and eosinophil number were generally greater for wild stocks compared to inbred animals, and differences were more pronounced for adults than juveniles.

Fluorosis in a wild cotton rat (Sigmodon hispidus) population inhabiting a petrochemical waste site.

We have developed an in situ mammalian model for evaluating environmental contamination using wild cotton rats. In a series of experiments, 200 male cotton rats were captured during 4 collection periods (spring 1991 = 35; fall 1991 = 60; spring 1992 = 53; fall 1992 = 52). A total of 103 of these cotton rats were captured from control sites, and the remaining 97 were captured from an abandoned oil refinery. All sites were located in the vicinity of Cyril, Oklahoma. There were alterations in the incisors of cotton rats captured from the refinery site. Normal color of cotton rat incisors is deep yellow-orange, which is imparted by a pigment normally produced by ameloblasts. Grossly, the upper incisors of 37 of 97 rats and lower incisors of 54 of 97 rats were affected. The affected incisors were white, chalky, and thin with striations and erosions of the enamel. Microscopic examination revealed that there were dysplastic and necrotic changes in the ameloblasts. The bone fluoride levels were significantly higher in rats captured from the refinery as compared to the rats captured from the control sites.

Spontaneous lytic activity against heterologous erythrocytes in cotton rat (Sigmodon hispidus) serum.

Although innate immunity has been well studied in laboratory animal models, no such documentation exists for wild species possessing a diversity of physiological adaptations to their environment. We examined the blood sera of 188 hispid cotton rats (Sigmodon hispidus) for naturally occurring hemolytic activity against heterologous erythrocytes. Ninety-two percent of the blood sera samples from cotton rats lysed sheep erythrocytes. All sera tested against chicken erythrocytes showed hemolytic activity, while only 44% of the same sera could lyse bovine erythrocytes. No hemolytic activity was present in cotton rat sera against erythrocytes from other rodent species (Eastern woodrat, Neotoma floridana, and pine vole, Microtus pinetorum). Hemolytic activity was heat labile and appeared to be mediated through the classical complement pathway. The protective nature of this hemolytic factor is unclear but it is probably directed at a more relevant molecule. These data, along with other reports of naturally occurring target specific serum factors in the cotton rat, may reflect the importance of innate protective mechanisms to small mammal populations.

Modifications of a cholinesterase method for determination of erythrocyte cholinesterase activity in wild mammals.

A method to determine erythrocyte cholinesterase (ChE) activity was modified for use in wild mammals. Erythrocyte ChE of California voles (Microtus californicus) was primarily acetylcholinesterase (AChE), which was similar to the brain and unlike plasma which was primarily butyrylcholinesterase (BChE). Triplicate erythrocyte AChE analyses from individual animals of several species of wild rodents revealed a mean coefficient of variation of 8.7% (SD = 4.3%). Erythrocyte ChE activity of several wild mammals of California revealed that mule deer (Odocoileus hemionus) had the highest erythrocyte AChE activity (1,514.5 mU/ml) and dusky-footed woodrats (Neotoma fuscipes) had the lowest activity (524.3 mU/ml). No ChE activity was found in erythrocytes of several species of birds and fish.

Hematological standard values in the cotton rat (Sigmodon hispidus).

The purpose of this study is to establish reference data on several hematological parameters in the cotton rat. Eight hematological values were measured in 28 males and 29 females at 16 to 18 weeks of age. Females showed significantly lower RBC, Ht and MCV values than males. Female Hb and PLT values tended to be lower than male values, although differences did not reach a conventional level of significance. WBC and PLT values varied widely in both sexes.