First report of fatal systemic Halicephalobus gingivalis infection in two Lipizzaner horses from Romania: clinical, pathological, and molecular characterization

Abstract

Halicephalobus gingivalis (H. gingivalis) causes a rare and fatal infection in horses and humans. Despite the zoonotic potential and severity of the disease, the epidemiology and pathogenesis of halicephalobiasis are still poorly understood. Several European cases of equine halicephalobiasis have been documented; however, in South-Eastern European countries, including Romania, equine neurohelminthiasis caused by H. gingivalis has not been previously described. Two Lipizzaner horses with a clinical history of progressive neurological signs were referred to the Pathology Department of the Cluj-Napoca (Romania) for necropsy. Both horses died with severe neurological signs. Gross examination and cytological, histological, and molecular analyses were performed. The stallions came from two different breeding farms. No history of traveling outside Romania was recorded. At necropsy, granulomatous and necrotizing lesions were observed in the kidneys, lymph nodes, brain, retroperitoneal adipose tissue, and lungs, indicating a systemic infection. Parasitological and histopathological analyses evidenced larval and adult forms of rhabditiform nematodes consistent with Halicephalobus species. Parasites were observed in both lymph and blood vessels of different organs and were also identified in urine samples. A subunit of the large-subunit ribosomal RNA gene (LSU rDNA) of H. gingivalis (673 bp) was amplified from lesions in both horses.To the authors' knowledge, this is the first report of equine systemic H. gingivalis infection in Romania and in South-Eastern Europe. Our findings provide new insights into the geographic distribution of specific genetic lineages of H. gingivalis, while also raising public health awareness, as the parasite is zoonotic.

Isolation and molecular characterisation of Halicephalobus gingivalis in the brain of a horse in Piedmont, Italy

“…Many cases of horses infected by H. gingivalis have been reported in different countries [1, 4, 7–10, 12, 13, 15, 16, 24–33] suggesting a ubiquitous distribution of the nematode. On the other hand, only eight fatal cases of H. gingivalis infection have been reported in humans in Canada [34], Australia [35], and Germany [36] and five in the United States [5].…”

“…For this reason, the prognosis is poor and the infection is usually diagnosed during post-mortem examination. To date, there is no intra vitam laboratory test, but the examination of urine has been recommended when the infection is suspected [7]. …”

“…The pathogenesis is unknown; it is likely the nematode penetrates oral and nasal mucosa or skin lacerations and ulcers, although a possible prenatal, perinatal and transmammary transmission has been suggested in two foals [6]. Moreover, the presence of larvae was demonstrated in urine samples [7], and a fly ( Musca autumnalis ) has been proposed as carrier of larvae [8]. Only eggs, larvae and adult females are found in the tissues involved suggesting a reproduction by parthenogenesis [8].…”

“…Infection may be restricted to local lesions or involve multiple organs through the hematogenous and lymphatic spread of the parasite [7, 9]. The most affected organs are brain, kidney, oral and nasal cavities, spinal cord, eye and lymph nodes [1, 7, 9–16].…”

“…The most affected organs are brain, kidney, oral and nasal cavities, spinal cord, eye and lymph nodes [1, 7, 9–16]. Occasionally, also legs, adrenal gland, lung, stomach, genitals, mammary gland, pituitary gland and heart [1, 4, 6, 15, 16] can be affected.…”