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The Challenge of Parasite Control
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Similarly, the transmission of filarial worms has been controlled by mass use of ivermectin. Adult worms in the definitive mammalian host are usually not killed. Both the infective L3 larvae, transmitted to humans through the bite of an arthropod vector, and the microfilariae produced by the adult worms are vulnerable. Consequently, if used prophylactically, ivermectin can render humans and other mammalian hosts refractory to infection. Because microfilariae are killed, arthropods in search of a blood meal on an infected mammalian host are unlikely to become infected if their host is taking ivermectin. In many cases of filariasis, of course, such as the elephantiasis caused by Wuchereria bancrofti, ivermectin will not assist the infected person, as pathology is the result of trauma caused by adult worms. A patient infected with Onchocerca volvulus, on the other hand, may benefit from ivermectin because circulating microfilariae cause the most serious symptoms of infection, including blindness. Box 9.2 describes a combination therapy that may include ivermectin, which improves treatment of canine heart-worm caused by the filarial parasite Dirofilaria immitis.
Inflammatory, Hypersensitivity and Immune Lung Diseases, including Parasitic Diseases.
Published in Fred W Wright, Radiology of the Chest and Related Conditions, 2022
Dirofilaria immitis (the dog heart worm) is a nematode conveyed by mosquito type vectors, the parasite being found in Canada, the USA (especially the Eastern states and on the Pacific coast), Australia, etc., its distribution presumably being related to the presence of wild foxes, dogs, etc. A subcutaneous infection precedes microfilaraemia. In man the worms die and produce small ischaemic lung infarcts, which may have calcified centres. A serological diagnostic test is available. The first human case was reported by Dashiell (1961). Leonardi et al. (1977) noted 61 cases, Levinson et al. (1979) four cases, Larrieu et al. (1979) 48 cases and Chesney et al. (1983) one case. Cholankeril et al, (1983) showed by CT that the nodules lie subpleurally in the lung. Kido et al. (1991) reported a case in Japan causing a small peripheral left lower lobe mass (which was resected) and a small pleural effusion.
Pulmonary Dogworm (Dirofilaria immitis) Infection Presenting as a Solitary Pulmonary Nodule
Published in Wickii T. Vigneswaran, Thoracic Surgery, 2019
The genus Dirofilaria consists of over 40 species of filarioid nematodes, but only two species, D. repens and D. immitis, have been known to affect humans. Canines are the primary hosts for Dirofilaria. D. immitis is commonly called dog heartworm, or dogworm, and has been reported more often in humans than D. repens on the American continent, but the reverse is true in other parts of the world [1]. The term heartworm is related to the residence of the adult worm in the right ventricle and pulmonary artery in dogs. D. immitis infection in the United States is more prevalent in the Eastern and Southeastern states [2].
Identification of potential vectors of Dirofilaria immitis and Brugia pahangi (Spirurida: Filariidae): First observation of infective third-stage larva of B. pahangi in Culex quinquefasciatus (Diptera: Culicidae)
Published in Pathogens and Global Health, 2022
Wei Yin Vinnie-Siow, Van Lun Low, Tiong Kai Tan, Meng Li Wong, Cherng Shii Leong, Nazni Wasi Ahmad, Yvonne Ai Lian Lim
Mosquito-borne filarioid nematodes such as Dirofilaria immitis and Brugia pahangi cause diseases to mammals, especially in domestic dogs and cats [1,2]. Dirofilaria immitis has a wide geographical distribution whereas B. pahangi is endemic in Southeast Asia (i.e. Malaysia, Thailand and Indonesia) [3,4]. Both parasites principally infect canine host, but the increasing reports of human filariosis highlight their potential as emerging zoonosis globally [2,5]. Transmission of filarioid parasites depends on the availability of microfilaraemic hosts, vectors, and favorable temperatures for the growth of the infectious stages in mosquitoes [6]. Mosquitoes of the genera Aedes, Culex, and Anopheles are the main vectors of filarioid parasites and they transmit L3 infective larvae of these parasites to potential hosts through their bites [7].
Human subcutaneous dirofilariasis: the ‘migrating’ skin tumor
Published in Case Reports in Plastic Surgery and Hand Surgery, 2021
Michelle Alexandra Mistry, Jens Hoejvig, Marie Helleberg, Christen Rune Stensvold, Pikka Jokelainen, Anders Noehr, Christian Bonde
Dirofilaria spp. are vector-borne parasitic nematodes, some of which are zoonotic [1]. From the Nordic countries, a small number of apparently imported human dirofilariasis cases [2,3] and one autochthonous human dirofilariasis case [4] have been reported. In Europe, especially D. repens has been spreading towards the north [5–8]. Dogs serve as the main reservoir of D. repens and can remain microfilaremic for months to years [2,9]. In the mosquitoes, microfilariae mature into infective larval stages, which can be transmitted to a new host when a mosquito takes a blood meal. In humans, dirofilariasis caused by D. repens can cause intermittent, painful erythema and itching as well as migrating subcutaneous lesions [3].
Extensive Chorio-retinal Damage Due to Dirofilaria Repens- Report of a Case
Published in Ocular Immunology and Inflammation, 2021
Prasad Gupta, Suchitra Pradeep, Jyotirmay Biswas, Pukhraj Rishi, Raman Muthusamy
Ocular Dirofilariasis is a zoonotic disease caused by D. repens and D. imitis. The natural reservoirs of these parasites include canines, felines, foxes and racoons. The intermediate hosts are arthropods like Aedes, Culex and Anopheles. It is believed that these parasites enter the eye through the ciliary circulation or through the optic nerve head. Humans can get infected by eating raw meat, raw uncooked fish, or from contaminated water. Dirofilaria can enter through mosquito bites also. The nematode parasite can cause pulmonary, subcutaneous or ocular lesions. Ocular complaints of redness, swelling, increased lacrimation and floaters are common. It is important to remove the parasite in toto as it can lead to structural damage to the eye, the retina in particular. It can lead to intense inflammation leading to panophthalmitis. DUSN is a multifocal chorio-retinitis caused by nematodes like Toxocara canis, Baylisacaris procyonis, Ancylostoma, Gnathostoma spinigerum, Strongyloides stercoralis and Brugia malayi. It is characterized by the presence of gray-white lesions in the deep retina, optic disc edema, vitreous inflammation, narrowing of the retinal optic vessels, optic nerve atrophy, and development of focal, linear crisscrossing or diffuse atrophic changes in the retinal pigment epithelium.4 DUSN results in unilateral loss of peripheral and central vision due to retinal inflammation and degeneration.5 Our patient also showed DUSN-like retinal picture. We have earlier reported a case of panuveitis cause due to Wuchereria Bancrofti which also concludes that a dead worm in the vitreous cavity can often incite a lot of inflammation and vitritis.6