Rhodococcus equi infection in foals: a report of an outbreak on a thoroughbred stud in Zimbabwe.

The study describes an outbreak of Rhodococcus equi infection in foals on a private stud in Zimbabwe which took place over two years, affecting twenty-four foals in total. Despite various preventive measures, the occurrence of infection rose the second year and its detection largely relied on clinical symptoms including fever, increased heartbeat and breathing rate, and nasal discharge.

Detailed Explanation

• This research is a detailed investigation into an outbreak of Rhodococcus equi infection, a type of bacteria that can lead to serious lung infections in foals. The situation was observed on a private stud in Zimbabwe over a two-year period.
• Over this period, the infection was clinically diagnosed in twenty-four foals from six different mares. Noteworthy is that each mare had foals infected in both years of tracking the outbreak. All affected foals displayed a fever, which served as an early symptom of the infection.
• The incidence of Rhodococcus equi infection increased in the second year in spite of rigorous hygiene measures relating to the housing and grassland of the animals. This increase suggests that these measures were not entirely successful in preventing the spread of the disease.
• Bronchopneumonic symptoms were only observed in the foals whose cases had advanced, reflecting the severity of the disease progression.
• The researchers used various diagnostic procedures to confirm the presence of Rhodococcus equi infection. These methods included clinical examination, culture of the organism from tracheal aspirates (sampling mucus from the windpipe), and imaging of the thoracic cavity. Blood tests revealed an increase in plasma fibrinogen (a protein involved in blood clotting) and counts of certain blood cells (platelets and neutrophils).
• Only one foal experienced diarrhea, which the researchers suggest was due to an infection of R. equi in the gut. None of the foals exhibited notable levels of anemia, a condition associated with lack of oxygen-carrying red blood cells.
• Treatment for the affected foals included oral administration of the antibiotics rifampicin and erythromycin, with dosage proportions matched to the weight of the animals. The treatment cycles continued until blood parameters normalized and remained stable for at least two weeks.