Neospora hughesi: experimental infections in mice, gerbils, and dogs.

This research explores the effects of different strains of the disease-causing parasite Neospora hughesi on various types of rodents and dogs, highlighting that the ability of these species to spread the parasites could lead to potential public health risks.

Introduction

Neospora hughesi is a parasite related to a disease known as equine protozoal myeloencephalitis (EPM), which predominantly affects horses. This study undertakes experimental infections in different animals to understand more about the disease and its severity. The animals tested in this study included BALB/c gamma-interferon gene knockout (gamma-INFKO), BALB/c, CD-1, and C57BL/6 strains of mice and gerbils. This experiment also involved a strain of N. hughesi known as Nh-A1, which was isolated from a horse from AL, USA.

Findings

• The study found that only the gamma-INFKO mice developed a severe form of the disease following infection with N. hughesi. These mice died between 19 to 25 days post-infection, suffering severe cardiac lesions.
• Gerbils infected with N. hughesi did not develop any clinical illness or significant microscopic anomalies. However, a conversion to a seropositive state (indicative of infection) were observed.
• When dogs were fed the brains of infected mice, they did not excrete parasite eggs or oocysts over a 23-day observation period, indicating a lack of transmission via this route.

Comparing Neospora Species

Two different strains of Neospora, namely the NC-1 and NC-Liverpool strains of Neospora caninum, were also examined. Infections with these strains led to death in gamma-INFKO mice 8-10 days post-infection with the most severe lesions appearing in the livers, spleens, and lungs.

Conclusion

The significant difference in pathogenicity between N. hughesi and N. caninum, coupled with the absence of oocyst excretion in dogs fed with N. hughesi-infected mice, lend credibility to the distinction between the two Neospora species. It also provides new insights into potential development of therapies primarily for equines affected by EPM, and opens the potential for further research on other animal infections and public health impacts.