Nodular Granulomatous Posthitis Caused byHalicephalobus(syn.Micronema) sp. in a Horse

Abstract

Key Words: Hal icephalo bus; ho rses; Micron ern a; posth iti s.Halicephalobus in fectio n a pparen tly is a worldwi de ph enomeno n; it has been rep orted o n five co ntinents in seven diffe re nt co untries : the Un ited Sta tes , th e United Kingd om , Jap an , Egypt, Switzer land , Th e Neth er lands: and Co lo mbia.' Inflam mation o f the ce ntra l nervo us system is a co nsistent fea ture of Halicephaiobus infecti on in h uman bei ngs' an d is a lm ost a lwa ys in vol ved in eq uine in fecti on s." In a review of reported Halicephalobus infecti on in horses, the bra in was th e m ost co m monly in vo lved tissue, follow ed in descend ing order by th e kidne ys, o ra l a nd nasal ca vities, lym ph nod es, lu ngs, spina l co rd, a nd adrena l gla nd, with single rep orts o f hea rt , liver, sto mac h, ganglion, a nd bon e involvcm cnt. !" G ran ulom a tou s os teoa rt hr itis indu ced by II. deletrix has a lso been rep orted ."In Ja nu ar y 1990, a 5-year-o ld ma le Ara bia n showho rsc was exa mi ned by an Albuq uerq ue vete rinaria n becau se o f mu lti ple nod ules on th e exte rna l lam ina of th e prep uce. T he a nima l was nat ive to New Mexico. O ther horses in th e stable we re un affected . Antecedent tra uma had not bee n o bse rved by the ow ner. No d ule di a me ters were 0.5-1 cm , an d th e ski n was ulcera ted over the surfaces. No ot he r cli nica l signs were ev iden t. A bio psy was perfo rm ed , and th e spec ime n was exa mi ned by a patho logist with the New Mexico Depa rtment of Agricult ure . After a prelimina ry d iagnosis of cuta neo us hali cephalo biasis, th e ho rse was treated with ivermect in an d di eth ylcarbamazine. Th e rem a in ing nodules subse q ue ntly regressed. T he biop sy spec ime n was subm itte d to the Ar me d Fo rces In stitute of Pat hology for co nfir ma tio n of the d iagnosis.Hi st o logically, the dermi s was marked ly thi ckened by a d i ffuse gra n ulo ma to us in filt ra te th at di srupted dermal co llagen a nd exte nde d to the ulcerat ed surface. T he in filtra te co ns isted of a b unda nt mu lti n uclea ted gia nt cells, ma crophages, cos ino phils, nc utrop hi ls, and nodula r aggregates of lym ph ocytes a nd plasm a cells (F ig. I ). T hro ugh o ut the section , there were numerou s ad ults , la rvae, and developing eggs ofa nem at od e par asite. Ad ult fem a les, 20 Jlm at th eir grea tes t d iam et er, were ob ser ved . No ma les were seen. The parasite had a smoot h, th in cuticle ; a plat yrn yar ia n-rnerorn yar ian muscul at ure; a psc ud ococ lum ; a rh abditifo rm esophag us co mposed of a corpus , isthm us, a nd bul b (Fig . 2); a nd a n in testina l tract co m posed of single n uclea ted lo w cuboi da l ce lls. There was a single geni ta l tube con ta ini ng o nly one mat ure egg. T he ovary was do rso flcxcd, a nd the uterus was ve ntroflexed a t th e v ulva (Fig. 3). La rvae were up to 10 Jlm in d ia me ter and also had rha bd itifo rm eso phagi. Adults an d Fig. I. Prepuce; horse. A pleocellu lar gra n ulo ma to us reaction surro und...

Halicephalobus gingivalis: A Rare Cause of Fatal Meningoencephalomyelitis in Humans

“…4 There have been only two reports of successful treatment of extra-central nervous system-localized halicephalobus infections in horses with ivermectin alone or with diethylcarbamazine. 10,11 An approach similar to treatment of disseminated strongyloidiasis may be prudent, specifically use of ivermectin alone or in combination with albendazole, 12 but this approach would require antemortem clinical suspicion of halicephalobiasis.…”

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.…”

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.…”