Epidemiology of equine grass sickness: a literature review (1909-1999).

The research paper is a comprehensive review of the studies conducted on the spread of equine grass sickness from 1909 to 1999 with a particular focus on England and Wales.

Geographical Spread of Grass Sickness

The paper traces the geographical spread of grass sickness, a disease affecting horses, across a span of 90 years, focusing particularly on England and Wales.

• The researchers have explored the timeline of the disease’s prevalence and how it spread across different regions. This could help in understanding the virulence and survivability of the disease, or perhaps to identify patterns or trends in the areas most affected.

Experimental Investigations

The study also endeavors to sum up the various experimental investigations conducted in the past to identify the causal agent for this illness.

• These researches include experiments with the aim to isolate and identify the organism or factor responsible for causing the disease.

Epidemiological Techniques

The paper catalogues a host of epidemiological techniques which were used to further study grass sickness in horses.

• The techniques range from basic clinical observations, typically including monitoring and documenting the signs and symptoms of the horses, to more advanced processes such as case-control studies. The latter involves comparing horses which have the disease (cases) to those that don’t (controls) to identify possible causes or risk factors.
• Logistic regression analyses have also been utilized. This aids in identifying the relationship between several independent risk factors (like age or breed) and the probability of the horse becoming sick.

Risk Factors

There are several risk factors for the onset of grass sickness in horses, some of which are reported more consistently than others.

• Firmly identified risk factors include the age of the horse, the time of year, and whether the horse has recently moved to a new pasture or premises. The research discusses these factors as they have been consistently identified in various studies.
• The paper brings to light some risk factors that have not been definitively linked to the sickness, due to inconsistent findings in studies. These factors include the weather, type of pasture, horse breed, supplementary feeding practices, and use of anthelmintics (anti-parasitic drugs). The research acknowledges the controversy around these factors and their roles in causing disease.