Persistent Ehrlichia chaffeensis infection in white-tailed deer

Four white-tailed deer (Odocoileus virginianus) were inoculated intravenously with a deer-origin isolate (15B-WTD-GA) of Ehrlichia chaffeensis. The course of infection was monitored using indirect fluorescent antibody (IFA), polymerase chain reaction (PCR), and culture over a 9 m period. All deer became rickettsemic within 24 days post inoculation (DPI), and all developed antibody titers >1:64 to E. chaffeensis by 17 DPI. Titers in all deer fell below 1:64 during 87 to 143 DPI. One deer exhibited a second period of seropositivity (peak titer of 1:256) from 207 to 271 DPI but was culture and PCR negative during this period. Rickettsemia was confirmed by reisolation of E. chaffeensis as late as 73 to 108 DPI in three deer. Positive PCR results were obtained from femur bone marrow of one deer and from rumenal lymph node of another (leer at 278 DPI. None of the deer developed clinical signs, hematologic abnormalities, or gross or microscopic lesions attributable to E. chaffeensis. Two uninoculated control deer were negative on all tests through 90 DPI at which time they were removed from the study. Herein we confirm that white-tailed deer become persistently infected with E. chaffeensis, have initial rickettsemias of several weeks duration and may experience recrudescence of rickettsemia, which reaffirm the importance of deer in the epidemiology of E. chaffeensis.     

Attempted transmission of Ehrlichia chaffeensis among white-tailed deer by Amblyomma maculatum

A deer was needle-exposed intravenously to Ehrlichia chaffeensis (Rickettsiales: Ehrlichieae) in canine macrophage (DH82) cells and 7 days later was infested with laboratory-reared Amblyomma maculatum (Koch) (Acari:Ixodidae) nymphs for acquisition feeding. After molting, the adult ticks were allowed to feed on a naive deer. The organism was reisolated from the needle-exposed deer by cell culture and E. chaffeensis DNA was detected in the deer's blood by PCR. Similar isolation/recovery techniques were used for the tick-exposed deer and no evidence of infection was found. Although these findings must be considered as preliminary owing to inadequate controls, the data suggest that A. maculatum is probably not a suitable vector for E. chaffeensis.     

Experimental infection of white-tailed deer (Odocoileus virginianus) with Ehrlichia chaffeensis by different inoculation routes

The infection dynamics of the tick-transmitted organism Ehrlichia chaffeensis were investigated in white-tailed deer (Odocoileus virginianus) using different routes of inoculation. Six deer were each inoculated with 5.4 x 10(6) DH82 cells infected with E. chaffeensis (Arkansas strain) by three different routes: intravenous (n = 2), subcutaneous (n = 2), and intradermal (n = 2). Two control deer were inoculated with uninfected cells. Infections were monitored for 54 days and were continued in one deer from each E. chaffeensis inoculated group for an additional 31 days. All deer inoculated with E. chaffeensis seroconverted (> or = 1: 64) and became 16S rDNA polymerase chain reaction and/or cell culture positive by post-inoculation day 15. There was no apparent (difference in susceptibility to infection between deer inoculated by different routes for the first 50 days based on detection of E. chaffeensis infection by PCR assay of blood or culture isolation. These results demonstrate infection of (deer by intradermal and subcutaneous routes for the first time.     

Transmission of Ehrlichia chaffeensis from lone star ticks (Amblyomma americanum) to white-tailed deer (Odocoileus virginianus)

Amblyomma americanum is an aggressive ixodid tick that has been implicated as a vector for several bacterial agents. Among these is Ehrlichia chaffeensis, which causes human monocytic (or monocytotropic) ehrlichiosis. In this study, experimental tick transmission of E. chaffeensis from infected lone star ticks to deer was revisited, and the question of whether it would be possible to re-isolate the organism from deer was asked, because this had not been done previously. Here, we were able to transmit a wild strain of E. chaffeensis from acquisition-fed lone star ticks to white-tailed deer. Ehrlichia chaffeensis was re-isolated from one white-tailed deer on multiple days during the infection and from another deer on one day during the infection. Peak rickettsemias for E. chaffeensis-infected deer were 17 DPI with acquisition-fed ticks and 14 DPI with needle-inoculated deer. This study supports the role of the lone star tick and white-tailed deer as vector and reservoir host for E. chaffeensis, demonstrating culture re-isolation of E. chaffeensis in deer infected by experimental tick transmission for the first time.     

Presumptive paratuberculosis in a Virginia white-tailed deer.

Paratuberculosis (Johne's disease) is described in a 5-month-old white-tailed deer (Odocoileus virginianus). Diagnosis was based on clinical signs and pathology.     

Congenital anomalies in a neonatal white-tailed deer in Alberta.

In September, 1973, a live male 2-3 day old white-tailed deer (Odocoileur virginianus) with multiple anomalies of the head and forelimbs was found near Lethbridge, Alberta. Notable gross findings inculded brachygnathia inferior, atypical incisor tooth alignment, medially folded ears, humero-radial arthrogryposis and bowing of the radius and ulna. Hematologic determinations indicated increased erythrocyte, hemoglobin and hematocrit levels. Histopathologic examination revealed mineralized spherites in the cerebellum and midbrain.     

Occurrence of rumenitis in a supplementary fed white-tailed deer herd.

Rumenitis was observed with increased frequency in a herd of white-tailed deer (Odocoileus virginianus) maintained on a high carbohydrate supplemental ration. Healing rumen scars were found in 4.4% (n=225) of animals examined in 1973; 24.1% (n=278) in 1974; and 42.5% (n=308) in 1975. The lesions often involved nearly the entire ventral blind sac of the rumen. Histopathologic studies did not define the etiologic agent and invasion by either fungi or Fusiformis necrophorus was not a prominent feature in the cases examined. Recovery appeared to be complete and the disease was not considered to be an important herd mortality factor.     

Tick infestations of white-tailed deer in Alabama.

Four species of ticks were collected from 537 white-tailed deer (Odocoileus virginianus), examined during the hunting seasons (November to January) of 1988-89 and 1989-90 at selected locations in Alabama (USA). Ixodes scapularis was the most common tick recovered (2,060 specimens) and infested 54% of the deer. Dermacentor albipictus was the second most frequent tick (1,253 specimens) and infested 15% of the deer. Amblyomma americanum was the third most frequent tick (315 specimens) and infested 24% of the deer; this was the only species of tick collected from deer at all sampling locations. Amblyomma maculatum was an infrequent parasite (five specimens) and infested only 1% of the deer; this tick species was only recorded during the 1989-90 season. Year-to-year and geographical differences in tick infestation parameters were noted. The data are compared with those reported for previous surveys of ticks infesting white-tailed deer in Alabama and adjacent states.     

Anthrax epizootic in white-tailed deer

Bacillus anthracis caused high mortality among white-tailed deer (Odocoileus virginianus) on Beulah Island, Desha County, Arkansas. Sixty-seven carcasses were located and the total loss was estimated between 200 and 300 deer. Range conditions indicated that the deer herd had greatly exceeded carrying capacity. Lesions in deer were similar to those ascribed to anthrax in domestic cattle, sheep, and goats.     

Experimental haemonchosis in white-tailed deer

White-tailed deer (Odocoileus virginianus) were successfully infected with Haemonchus contortus of sheep origin. Individual deer in each of three groups were inoculated with 0, 25,000, and 100,000 larvae respectively. Severity of infection was related to dose and signs of infection were most obvious in the heavily inoculated animals. Infected deer were weak, emaciated, and anemic, similar to the clinical response in sheep. Hemoglobin, packed cell volume, and total serum protein values for both infected groups were significantly lower than for the controls. Inhibition of larval growth was noted in both infected groups, but was most pronounced in the group which received 100,000 larvae. Inhibition of egg production was also noted in this group. The potential importance of H. cortortus in deer populations was discussed.     

Salmonellosis in white-tailed deer fawns

Experimental infection of white-tailed deer fawns with Salmonella meleagridis was accomplished. The fawns suffered clinical illness, similar to spontaneous cases observed in the field. This disease may be an important factor in fawn survival in wild herds based on the frequency with which Salmonellae could be isolated in wild fawns. The clinical disease was acute, characterized by rapid depression and dehydration. Death ensued in three of eight experimental cases. The survivors suffered clinical illness.     

Spontaneous dermatophilosis in twin white-tailed deer fawns.

Twin white-tailed deer (Odocoileus virginianus) fawns captured in Morris County, New Jersey, displayed papular, darkly pigmented scabs principally on the skin overlying the nasal bones, dentary, commissure of the lips and ears. Histopathological and bacterial examinations revealed Dermatophilus congolensis. The epidermitis caused by this bacterium apparently had developed within the first 12 to 14 days after birth and had begun to regress by one month of age. The location of the lesions suggested transmission during nursing from an infected doe. This is believed to be the first confirmed report of this zoonotic disease in white-tailed deer, with isolation of the etiologic agent, outside the State of New York. Epizootiological considerations are discussed.     

Natural and experimental infection of white-tailed deer (Odocoileus virginianus) from the United States with an Ehrlichia sp. closely related to Ehrlichia ruminantium

An Ehrlichia sp. (Panola Mountain [PM] Ehrlichia sp.) closely related to Ehrlichia ruminantium was recently detected in a domestic goat experimentally infested with lone star ticks (LSTs, Amblyomma americanum) collected from Georgia, USA. The infected goat exhibited pyrexia and mild clinical pathologic abnormalities consistent with ehrlichiosis. At least two other Ehrlichia species (Ehrlichia chaffeensis and Ehrlichia ewingii) are maintained in nature by a cycle involving LSTs as the primary vector and white-tailed deer (Odocoileus virginanus) as a known or suspected reservoir. To investigate the possibility that white-tailed deer are potential hosts of the PM Ehrlichia sp., whole blood samples collected from 87 wild deer from 2000 to 2002 were screened with a species-specific nested PCR assay targeting the citrate synthase gene. In addition, two laboratory-raised white-tailed deer fawns were each infested with 120 wild-caught LST adults from Missouri, USA, and blood samples were periodically collected and tested for the PM Ehrlichia sp. Of 87 deer tested from 20 locations in the southeastern United States, three (3%) deer from Arkansas, North Carolina, and Virginia were positive for the PM Ehrlichia sp. Wild-caught ticks transmitted the PM Ehrlichia sp. to one of two deer fawns, and colony-reared nymphal LSTs acquired the organism from the deer, maintained it transstadially as they molted to adults, and transmitted the PM Ehrlichia sp. to two na?ve fawns. These findings indicate that white-tailed deer are naturally and experimentally susceptible to infection with an Ehrlichia sp. closely related to E. ruminantium and are able to serve as a source of infection to LSTs.