Published large-scale vector-borne organism (VBO) PCR prevalence studies in domestic cats are limited. The prevalence of VBOs in feline blood samples submitted for PCR testing by a veterinary diagnostic laboratory between January 2, 2019, and December 23, 2025 (n = 7581) was determined. Feline blood samples were tested for Anaplasma, Apicomplexa, Babesia, Bartonella, Cytauxzoon, Ehrlichia, hemotropic Mycoplasma, and Rickettsia. VBOs were detected in 1373/7581 (18.1%) blood samples, with Mycoplasma haemominutum (8.87%) and Bartonella henselae (5.99%) being the most prevalent. Hepatozoon spp. were identified in 40 (0.58%) cats, prompting further genetic and epidemiologic characterization. Sequence analysis of a 182-bp fragment of the Hepatozoon 18S rRNA gene from 40 PCR-positive cats identified seven haplotypes with the highest sequence similarities to Hepatozoon silvestris, Hepatozoon felis, and bobcat-associated Hepatozoon spp. Phylogenetic analysis resolved the variants into major groups clustering with H. silvestris, H. felis, and nondomestic felid-associated Hepatozoon spp. Most Hepatozoon-positive cats originated from the Northeast and Mid-Atlantic regions of the United States (34/40; 85.0%), of which seven infections (7/40; 17.5%) involved cats undergoing blood donor screening. Overall, PCR testing confirmed infection with a VBO in approximately one in five cats tested in the U.S and Canada. Hepatozoon infections were more common than previously recognized, underscoring the value of Hepatozoon-specific PCR in feline VBO diagnostic testing.
The infectivity of Ascaridia galli eggs is central to experimental parasitology and understanding parasite transmission in poultry. While embryonation and larval motility are commonly used indicators of egg viability, their relationship with actual infectivity is poorly defined, particularly as eggs age during laboratory storage. This study evaluated temporal changes in the viability and infectivity of A. galli eggs aerobically stored at 25 °C for 3, 6, 12, 18, 24, 30 and 36 weeks from time of collection. Viability was assessed using morphological integrity, in ovo larval motility, and hatch-staining assays, while infectivity was determined through experimental infections in day-old chickens (n = 24 per egg storage period (SP)). For all SP groups, infective doses were based on the number of morphologically viable eggs or motile larvae administered (300 eggs/bird). Across all in vitro measures, eggs maintained high viability for up to 12 weeks (78–91%), then progressively declined to 19% by 36 weeks, with an average loss of about 2% per week. Infection outcomes closely mirrored in vitro viability: total worm counts per bird decreased from 9 to 10 worms for 3–12-week-old eggs to 2 worms for 36-week-old eggs. Correspondingly, infectivity fell from 3.04 to 3.35% in younger eggs (3–12 week) to 0.68% in the oldest eggs. By 8 weeks post-infection, adult worms accounted for 90–95% of populations from young-egg infections, compared with only 48–52% in infections from older eggs, which contained up to 51% immature worms. Adult worm size and reproductive potential also declined with egg age, and sex ratios became slightly male-biased in older cultures. Empirically derived conversion factors (CFv) provided a quantitative link between in vitro viability and infectivity within the viable egg subpopulation, while adjusted CFₜ extended this estimate to the total egg population, with linear interpolation enabling estimation for SP-specific infectivity. These findings underscore that not all viable-looking eggs are infective and highlight a defined period of optimal infectivity for experimental use. Overall, the study informs best practices for aerobic storage of A. galli eggs in the laboratory and provides a framework for applying in vitro viability data to experimental infections and modelling transmission risk in poultry systems.
Under European Union (EU) regulations, organic pigs must have access to outdoor areas, where gastrointestinal nematodes (GIN) represent health concerns; however, management, including stocking rate, may influence infections. We investigated infections with Ascaris suum and behaviour in finisher pigs kept at different stocking rates, with groups having access to willow paddocks. The two-year study included indoor control (I-Ctrl), low stocking rate (L-SR), and high stocking rate (H-SR) treatments. In Year 1, 44 pigs were allocated to seven replicates (one I-Ctrl, three L-SR, and three H-SR); in Year 2, 60 pigs were allocated to nine replicates (three per treatment). In Year 1, more than two-thirds of L-SR and H-SR pigs remained negative for faecal egg count (FEC), while a few pigs had consistently high FEC. The FEC differed among treatments (p = 0.004), with higher FEC in I-Ctrl than L-SR and H-SR, although I-Ctrl comprised only one replicate. In Year 2, egg-excreting pigs increased from 6/59 at arrival to 37/59 at study end, while incidence risks in replicates ranged from 13% to 71% in H-SR, 25–100% in L-SR, and 75–100% in I-Ctrl. No effect of treatment was detected. Stocking rate was not associated with soil egg counts or behavioural outcomes. Soil egg count correlated with replicate mean FEC (rho = 0.94, n = 6, p = 0.017). Overall, no consistent difference in A. suum infection was detected between stocking rates. Infection patterns varied among individuals and replicates, and pigs without paddock access showed similar or higher infection levels than outdoor groups.
