Molecular Evidence for Persistence of Anaplasma phagocytophilum in the Absence of Clinical Abnormalities in Horses after Recovery from Acute Experimental Infection

Background: Anaplasma phagocytophilum infects several mammalian species, and can persist in sheep, dogs, and calves. However, whether this organism persists in horses or induces long-term clinical abnormalities is not known.
Objectives: To evaluate whether A. phagocytophilum can persist in horses and to document clinical findings for 3 months after complete recovery from acute disease.
Animals: Five clinically normal adult horses that had recovered spontaneously from experimentally induced acute disease caused by a Swedish equine isolate of A. phagocytophilum .
Methods: Horses were monitored for up to 129 days post inoculation (PI) by daily clinical examination and at least alternate day blood sampling for evidence of A. phagocytophilum on polymerase chain reaction (PCR) and blood smears. All horses were euthanized and underwent postmortem examination.
Results: All horses were periodically PCR positive after recovery from acute infection. Before day 66 PI 2 horses were persistently PCR negative whereas 3 horses were intermittently PCR positive. Subsequently, 4 of 5 horses were intermittently PCR positive, particularly after stress mimicking interventions. One animal was positive immediately before postmortem examination. Clinical abnormalities related to persistence of anaplasma were not observed. No specific changes were found at postmortem examination, and all sampled tissues from all horses were negative on PCR for A. phagocytophilum .
Conclusions and Clinical Importance: Infection with A. phagocytophilum can persist in the horse for at least 129 days. However, the continued presence of the organism is not associated with detectable clinical or pathological abnormalities.     

Death of a horse infected experimentally with Anaplasma phagocytophilum

A 19-year-old horse that was one of a group of six horses infected experimentally with Anaplasma phagocytophilum for a study of the pathogenesis of equine granulocytic ehrlichiosis died suddenly two days after first showing clinical signs of disease. The clinical signs and laboratory findings observed before its death were similar to all those of the other infected horses, and to previous reports of this disease. A postmortem examination revealed widespread haemorrhaging in its internal organs, and vasculitis and thrombosis in the kidneys. These changes are consistent with disseminated intravascular coagulation, which has previously been reported in human beings infected with the presumably identical agent of human granulocytic ehrlichiosis.     

Landscape improvement, or ongoing degradation – reconciling apparent contradictions from the arid rangelands of Western Australia

Recent quantitative site-based monitoring and qualitative aerial and ground traverses provide contrasting assessments of the health of much of the arid shrublands of Western Australia extensively grazed by livestock (‘rangelands’). Although these results seem incompatible, we explain the apparent contradictions based on landscape succession processes operating at multiple levels of ecological organisation. Specifically, we suggest that the intact areas in which site-based monitoring is conducted are contracting as catchment canalisation and desiccation increase. However, the impacts of these processes have not yet become manifest at the site scale. The site-based system addresses important regional questions. These relate to the large, relatively intact areas away from most active surface flows, which should be a focus for resource conservation, given practical limits to repairing widespread degradation with low management inputs. We provide a complementary set of questions to provide a more comprehensive audit of rangeland dynamics in the context of underlying hierarchical landscape patterns and processes that might threaten intact areas. We recognise the need to match questions and levels of ecological organisation and the implications these have for sampling. We also recognise the difficulty in producing concise statements of change for clients when reporting on complex ecological issues and processes. Without a clearly articulated, and well understood, hierarchical model of pattern and process within which apparently contradictory findings can be reported meaningfully, policy makers may be confused by the results, with the consequent risk of policy inaction.     

Prehistoric rock avalanches in the olympic mountains, washington

Rock avalanches blocked streams in the Olympic Mountains southwest of Puget Sound during the past few thousand years. Limiting radiocarbon ages indicated that three or four of six avalanches occurred from 1000 to 1300 years ago or shortly thereafter. Most of the dates were from the outer preserved rings of trees drowned behind avalanche dams. These three or four avalanches may be coeval not only with one another but also with abrupt tectonic deformation in western Washington. No rock avalanches in the Olympic Mountains are known to have resulted from storms or earthquakes during the past century. The avalanches strengthen the case that a large prehistoric earthquake occurred in the Puget Sound region.     

Ectopic ureter in the horse: Three cases and a review of the literature

Ureterovesicular anastomosis resulted in resolution of the clinical signs of urinary incontinence in three horses with unilateral ectopic ureter. Follow-up of two of the horses ten months and three years later indicated no further urinary tract problems; the third horse died four days after surgery from intestinal infarction.

Diagnosis can be readily confirmed by antegrade or retrograde ureterography, or endoscopic visualization of the ectopic ureteral openings. Nephrectomy appears indicated in cases of unilateral ectopic ureter with associated ipsilateral urinary tract infection or hydronephrosis, providing the contralateral kidney has normal function. Ureterovesicular anastomosis appears to be indicated in the management of unilateral ectopic ureters in the absence of ascending urinary tract infection or hydronephrosis, and in cases of bilateral ectopic ureters.

     

Birds as agents of seed dispersal in a human-dominated landscape in southern Costa Rica

Birds play vital roles as seed dispersers helping to maintain and restore plant communities. With restoration increasingly key to global conservation, it is important to understand the landscape attributes and bird community characteristics that most influence avian seed dispersal in human-altered landscapes. We examined bird community structure and seed-dispersal patterns in agricultural countryside in Costa Rica that is typical of much of the Neotropics. Contrary to expectations, bird abundance, not richness, best predicted the richness of bird-dispersed seeds. Neither forest patch size or proximity, nor total tree cover, influenced seed dispersal. The richness and abundance of dispersed seeds, however, was strongly correlated with “wetness,” a remotely-sensed metric of vegetation, at several scales. These results suggest that in this human-dominated tropical region: (1) bird abundance, not species richness or size, may drive seed dispersal, and (2) remote-sensing combined with field verification can detect landscape elements that are helpful for maintaining the option of bird-mediated reforestation.