A nodular granulomatous posthitis caused byHalicephalobussp. in a horse

Abstract

This report describes a case of nodular posthitis caused by Halicephalobus gingivalis in a 24-year-old warmblood horse. Macroscopic examination revealed a multinodular, partially ulcerated mass on the external lamina of the prepuce. Nematode migration from unfixed biopsy material in phosphate-buffered saline revealed adult nematodes with the typical morphological features of H. gingivalis: distinctive rhabditiform oesophagus with corpus, isthmus and bulb and the dorsoflexed ovary. The main histopathological features consisted of submucosal confluent granulomatous foci containing cross- and tangential sections of larval and adult nematodes surrounded by cellular debris, epitheloid macrophages, multinucleated giant cells, lymphocytes and plasma cells. Therapy including oral administration of moxidectin and local application of an ointment containing prednisolone and moxidectin was initiated but clinical response was poor. Five months later, the nodular mass was still present and histologically, the same lesions with numerous intact nematodes were identified. In the present case, a localized infection with granuloma formation in the area of the prepuce was observed. Clinically, it cannot be distinguished from other nematode infections or even from a squamous cell carcinoma. An accurate clinical examination followed by histopathological and parasitological examinations was necessary to establish the final diagnosis. This case is unusual in that the lesions were locally very extensive (10 cm), but they remained confined to the preputium and the nematodes did not spread haematogenously to other internal organs.

Anthelmintic tolerance in free-living and facultative parasitic isolates ofHalicephalobus(Panagrolaimidae)

“…A few cases have been described in which the infection was recognized in time and the horse was successfully treated (Dunn et al 1993;Pearce et al 2001;Müller et al 2008). Still, most infections were only recognized post-mortem after a thorough autopsy.…”

First Human Case of Fatal Halicephalobus gingivalis Meningoencephalitis in Australia

“…To date, 27 other cases of infection in animals have been described, mainly in horses, with 4 survivors (18,25,26,29). Micronema deletrix was used as a synonym for this species in the 20th century.…”

“…In the present case, histopathological examinations of other organs did not indicate any dissemination of the nematode beyond the central nervous system (CNS). In animals, H. gingivalis had been linked to oromaxillary Case Report infections and posthitis, suggestive of initial mucosal exposure to the invasive larvae, followed by dissemination (17,18,20,29,30). Exposure through the oromaxillary route may explain the common neurological involvement.…”

Intestine ultrastructure of the facultative parasite Halicephalobus gingivalis (Nematoda: Panagrolaimidae)

“…Most infections in horses are only recognised postmortem after a thorough autopsy in which the extremely small nematode is found. The clinical symptoms are very variable depending on which organs are infected (Blunden et al, 1987;Spalding et al, 1990;Rames et al, 1995;Johnson et al, 2001;Grosche et al, 2002;Mandrioli et al, 2002;Müller et al, 2008). In only a few cases does the infected animal survive (Dunn et al, 1993;Pearce et al, 2001;Müller et al, 2008).…”

“…The clinical symptoms are very variable depending on which organs are infected (Blunden et al, 1987;Spalding et al, 1990;Rames et al, 1995;Johnson et al, 2001;Grosche et al, 2002;Mandrioli et al, 2002;Müller et al, 2008). In only a few cases does the infected animal survive (Dunn et al, 1993;Pearce et al, 2001;Müller et al, 2008). Infection in three human * Corresponding author, e-mail: Pamela.Fonderie@ugent.be cases has also been described, all with a fatal outcome (Hoogstraten & Young, 1975;Shadduck et al, 1979;Gardiner et al, 1981).…”