Diversity of the infracommunities of strongylid nematodes in the ventral colon of Equus caballus from Rio de Janeiro state, Brazil.

The study investigates the diversity of nematodes, particularly strongylid nematodes, in the ventral colons of adult horses from Brazil’s Rio de Janeiro region, revealing instances of multi-species infections with high dispersion and prevalence of certain species.

Research Method: Nematode Analysis

• The research involved examining nematodes found in the lower stomach (ventral colon) of 31 adult horses. Among these, 24 were males and 9 were females. The horses were all from the metropolitan region of the state of Rio de Janeiro.
• The total number of strongylid nematodes (a type of worm that affects mammals) recovered was 53,444. This constituted 86.4% of the adult nematodes recovered from the horses’ ventral colons.

Discovered Nematode Species

• The strongylid nematodes belonged to 28 different species, within two main families – 21 species falling under the Cyathostominae, and seven species falling under the Strongylinae.
• In addition to adult nematodes, the study also identified larval forms, which made up 13.6% (8407) of the strongylids recovered.
• Interestingly, it was observed that 49% of the strongylid nematodes were located in the ventral colon of the horses.

Key Findings: Nematode Prevalence and Dispersion

• Among the species found, Cyathostomum tetracanthum, Cylicocyclus nassatus, Cylicostephanus minutus, Cylicostephanus longibursatus, Cylicostephanus leptostomus, Cylicostephanus calicatus, and Cylicostephanus goldi were the most prevalent, making up 93.2% of the adult population.
• Because of their prevalence, these species were classified as “central” species, except for C. goldi. Other species were categorized as “secondary” (8 species) and “satellite” (14 species).
• Researchers utilized Green’s aggregation index to gauge species distribution; a low index revealed high dispersion among the identified “central” species, meaning they were present in a large number of individual host communities, thus confirming high prevalence.
• The study determined that only 12.1% of horses were either free of infection or infected by a singular species.
• The majority of infections were multiple, with horses hosting anywhere between 3 to 23 different species of nematodes. This underscores the complexity of these parasitic ecosystems and their potential impact on equine health.