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Parasites and Conservation Biology
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Another member of the same nematode genus, Baylisascaris procyonis, is also worth mentioning here. It is a common parasite of the widespread North American raccoon, Procyon lotor. The nematode is dangerous to people and other animals because if eggs are ingested, the larvae that hatch from the eggs begin to wander (visceral larval migrans), causing problems ranging from mild discomfort to respiratory problems to ocular damage and severe neurological problems including seizures and coma. Eggs of this parasite are plentiful around the characteristic communal defecation spots for raccoons called latrines. Care should be taken to prevent raccoons from getting close to or into homes and to safely destroy their latrines to avoid contact with eggs and to prevent infections in dogs, also capable of serving as a definitive host for this parasite.
Toxocara
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Ocular toxocariasis (OT) (also known as OLM, or toxocaral retinitis) is a compartmentalized toxocariasis resulting mainly from T. canis and T. cati larval migration to the eye. Occasionally, roundworm (Baylisascaris procyonis) from raccoon (Procyon lotor) may be implicated in a similar disease. Apart from unspecific symptoms (e.g., fever, anorexia, nausea, headache, abdominal pain, vomiting, sleep and behavior disorders, pharyngitis, pneumonia, cough, wheeze, limb pains, and cervical lymphadenitis), OT is associated clinically with unilateral visual loss (due to granuloma-related retinal damage, retinal comorbidities, and intraocular inflammation; >50% of cases), leukocoria, intermittent strabismus, uveitis, conjunctivitis, keratitis, iridocyclitis, optic papillitis, optic neuritis, diffuse chorioretinitis, endophthalmitis (a type of panuveitis manifesting as a red, painful eye with diffuse intraocular inflammation accompanied by marked vitreitis, secondary cataract, and mild anterior chamber reaction; <25% of cases), retinal granulomatous lesion (or posterior pole granuloma; 25%–36% of cases), and peripheral vitreous mass (or peripheral granuloma; 50%–64% of cases) in young children (of 5–10 years of age) and young adults. In addition to ocular inflammation and granuloma, other vitreoretinal comorbidities in OT include epiretinal membrane, vitreous opacity, tractional/rhegmatogenous retinal detachment, macular edema, and macular hole. In addition, some OT patients may be subclinical and only diagnosed during a routine eye examination [19].
Parasites and Conservation Biology
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2015
Eric S. Loker, Bruce V. Hofkin
One of the very symbols of the conservation movement, the giant panda (Ailuropoda melanoleuca), serves to conclude this section because it points out many of our concerns and uncertainties regarding parasites and endangered species. Giant pandas have in recent years been threatened increasingly by infection with an ascarid nematode, Baylisascaris schroederi (Figure 8.10), the larvae of which undergo extensive migrations (called visceral larval migrans) through sensitive panda tissue and can cause death. The adult worms living in the panda’s intestine can also cause obstructions. Even in a high profile case like this, we are not sure why B. schroederi is now more of a problem for pandas than in the past. Are new ecological circumstances, perhaps reduced or fragmented habitats, involved? Are there other hosts— perhaps introduced hosts—that facilitate maintenance of the parasite? Also, as there are cases of other hosts, such as the North American Allegheny wood rat Neotoma magister, being imperiled by related Baylisascaris parasites, it serves to remind us that the parasites of relevance to conservation biology are diverse. We have highlighted roles of viruses, fungi, or Plasmodium parasites in threatening host species, but even macroscopic helminths can get into the act as well.
Multifocal Chorioretinitis with Serous Macular Detachment in Diffuse Unilateral Subacute Neuroretinitis (DUSN): Unique Presentation and a Diagnostic Dilemma
Published in Ocular Immunology and Inflammation, 2023
Amit Kumar Deb, Jawahar Satya Babu, Priyanka Ramanathan, Sandip Sarkar, Goutham Raja, Charita Abburu
Diffuse unilateral subacute neuroretinitis (DUSN) is an infectious, progressive retinal disorder resulting in severe visual disturbances.1 The parasitic organisms most commonly implicated are Baylisascaris procyonis, Ancylostoma caninum, and Toxocara canis.2 DUSN commonly presents as a unilateral condition in children and young adults, but bilaterality has also been observed.3 Clinical manifestations in the acute phase includes mild vitreous inflammation, optic disc edema, gray-white retinal lesions, and pigmentary changes in retinal epithelium. Late-stage DUSN is characterized multifocal choroiditis, progressive retinal pigmentary epithelial (RPE) changes, narrowing of retinal arteriole, and optic disc atrophy.1,4 Serous macular detachment in DUSN has not been reported before in the literature. Serous detachment with multifocal choroiditis is commonly seen in conditions like Vogt–Koyanagi–Harada (VKH) syndrome, sympathetic ophthalmia, tuberculosis (TB), sarcoidosis etc.5 We, hereby, describe a case of DUSN who presented with unique features of serous macular detachment with multifocal choroiditis and no visible worm initially, thereby, posing a diagnostic dilemma.
Diffuse Unilateral Subacute Neuroretinitis Evolving With Submacular Granuloma
Published in Ocular Immunology and Inflammation, 2021
Thiago José Muniz Machado Mazzeo, Nelson Batista Sena, Mario Martins Motta, André Luiz Land Curi
Parasites of different sizes and species have been proposed as the etiologic agent of DUSN, including Ancylostoma caninum, Toxocara canis, and Baylisascaris procyonis. Thus, it is hypothesized that different infectious worms may be considered as the likely cause of a both autommune and toxic form of nematode retinopathy. Because serologic testing is variable, the definitive diagnosis is made when typical clinical characteristics of DUSN are found in conjunction with an intraocular worm. Ancillary tests can assist in the differential diagnosis when the nematode cannot be visualized, such as Optical Coherence Tomography (OCT), Fluorescein angiography and others.3–5