Habronematidosis in Equids: Current Status, Advances, Future Challenges

Abstract

Over the past few decades, among equine parasitoses caused by gastrointestinal nematodes, habronematidosis has been discontinuously studied worldwide. Habronematidosis is a parasitic disease distributed all over the world. It is caused by Habronema microstoma, Habronema muscae, and Draschia megastoma (Spirurida, Habronematidae), and it is maintained in the environment by muscid flies which act as intermediate hosts. At larval and adult stages these species live in the stomach of domestic and wild equids. However, the larvae can also be found on the skin, causing lesions known as "summer sores", and occasionally on other body areas, such as ocular and genital mucosa (muco-cutaneous habronematidosis) and lung, liver, brain parenchyma. Depending on the parasite's developmental stage and localization site, clinical signs vary from mild to severe. Habronematidosis is responsible for significant economic losses, mostly when sport horses are affected, because their performances are impaired and the infection can be unaesthetic. We used three on-line databases for searching the articles on habronematidosis according to the selected inclusion criteria; a total of 250 contributions, published between 1911 and 2020 were analyzed. This review summarizes the key features of pathogenesis, epizootiology, diagnosis, treatment, and control of habronematidosis, and highlights the current knownledge about its geographical distribution and spread. Anthelmintic drugs are the most widely-used tools against habronematidosis; given the known risk of anthelmintic resistance in some nematodes affecting horses, this aspect should also be explored for habronematidosis. Dedicated research is essential to fill gaps of knowledge and increase the understanding of habronematidosis to maximize equine health, reduce economic losses and sanitary impact associated with this parasitic infection.

Summer Sores Secondary to a Hoof Crack in an Andalusian Stallion

“…The positivity of the horse at the molecular examination of feces (i.e., at present the most reliable approach to diagnose gastric habronemosis) further supports the primary role of Habronema in causing the hoof lesions and confirm previous data which showed the correlation between animals suffering from summer sores and concomitant gastric habronemosis [1,2].…”

“…Habronematidosis is a parasitic infection caused by adult and larval stages of Habronema microstoma , Habronema muscae and Draschia megastoma (Nematoda, Spirurida, Habronematoidea). These nematodes are transmitted by biting and secretophagous flies, e.g., Stomoxys calcitrans and Musca domestica [ 1 ]. When infective third larval stages (L3) are deposited on the nostrils and lips and swallowed by the equid, the parasites reach adulthood in the stomach and cause a gastric disease.…”

“…In Europe Habronema spp. is much more distributed than D. megastoma , thus gastric and (muco-)cutaneous habronemoses are the most important diseases caused by these parasites [ 1 ].…”

Parasitic diseases of equids in Iran (1931–2020): a literature review

“…In Iran, eggs and adults of O. equi have been reported (mostly in fecal egg count) in horses [ 35 , 37 , 115 , 116 , 118 , 122 , 124 , 136 , 148 ] and donkeys [ 36 , 131 , 148 ]. Probstmayria vivipara , however, has only been reported in necropsied donkeys with > 500,000 worms collected from a single animal [ 131 , 149 ].…”

Co‐occurrence of papillomas related to Equus caballus papillomavirus type 2 and cutaneous habronemiasis

“…Habronematidae nematodes have a worldwide distribution. However, there are few data on the prevalence of equine cutaneous or mucocutaneous habronemiasis because the description of these cases is often limited to case reports, for instance, in the UK, Belgium and Italy (Barlaam et al 2020). An increase in (peri)ocular habronemiasis has been recently suspected in the Netherlands (Verhaar et al 2018).…”