Trichostrongyle infections in domestic ruminants from Egypt: A systematic review and meta-analysis

Abstract

Trichostrongylid nematodes can cause serious loss in the livestock economy; nevertheless, infections with these ubiquitous nematodes in animals from developing countries are largely neglected. The present paper provides a systematic review and meta-analysis to evaluate the status of trichostrongyle infections in domestic ruminants from Egypt. Out of 626 collected publications, 118 were defined suitable for inclusion in this review and represented trichostrongyle infections in 5 ruminant species (sheep, goats, cattle, buffaloes and camels) from Egypt. Published surveys have mostly focused on sheep, which had the highest (44.8%) pooled prevalence of trichostrongyle infections based on 95% confidence interval (35.9-53.6%) with no significant variations among sheep in different Egyptian regions. Goats had lower infection prevalence (31.2%, 21.5-40.8%) in comparison to sheep, and no significant regional differences were also found. The management and marketing practices likely account for the wide distribution of infection among small ruminants across Egypt. Variable trichostrongyle infection rates were estimated for camels (38.8%, 28.9-48.7%), cattle (27.4%, 14.4-40.3%) and buffaloes (12.2%, 8.0-16.4%). The prevalence of infection was significantly high during winter (52.1%, 32.2-72.1%), which provide favorable conditions for development and survival of larvae on pastures. The most common trichostrongyle identified in infected animals was Haemonchus contortus. The parasite was detected in 38.8% (29.9-47.6%) of infected sheep, 35.3% (24.8-45.7%) of infected goats and in 40.6% (18.6-62.5%) of infected camels. Clinical infections have been reported in a limited number of studies. Analysis of fecal egg counts (FECs) revealed that more than half (52.7%, 30.4-75.0%) of the tested sheep had low counts (<500 eggs per gram EPG), whereas only a few sheep (6.1%, 3.5-8.7%) had high counts >2000 EPG, implying that subclinical infections are common; however, the clinical infections cannot be completely ruled out. Anthelmintic resistance does not appear to be serious in trichostrongyle populations infecting ruminants from Egypt; nonetheless there have been a few cases of albendazole resistance in trichostrongyles infecting sheep. This paper contributes to a better understanding of the epidemiology and economic implications of trichostrongyle infections in ruminants from Egypt, which is crucial for establishing effective control strategies against these ubiquitous nematodes.

Keywords: Anthelmintic resistance; Egypt; Epidemiology; Haemonchus contortus; Ruminants; Trichostrongyles.