Inflammatory, Hypersensitivity and Immune Lung Diseases, including Parasitic Diseases.
Fred W Wright in 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.
Host Defense and Parasite Evasion
Eric S. Loker, Bruce V. Hofkin in Parasitology, 2015
Other parasites take a less subtle approach; they simply degrade enzy-matically any antibodies that manage to adhere to them, using proteases incorporated into their tegument. Dirofilaria immitis, the filarial worm responsible for canine heartworm, Schistosoma mansoni, the liver fluke Fasciola hepatica, and the protozoa Giardia lamblia, Trichomonas vaginalis, and Entamoeba histolytica all avail themselves of this tactic. The case of E. histolytica is particularly interesting. We mentioned earlier that this invasive and pathogenic species is capable of avoiding complement-mediated lysis, whereas the noninvasive and nonpathogenic E. dispar is not. Likewise, although E. histolytica rapidly degrades secretory IgA, E. dispar lacks this capacity. These mechanisms of immune evasion may explain in part the differences in pathogenicity between these two amebas.
Filariasis
F. Y. Liew in Vaccination Strategies of Tropical Diseases, 2017
Filarial nematodes are obligate extracellular parasites of virtually all vertebrate species. Fortunately, most of these helminths are able to fully develop in only one or at most a small number of different hosts; this narrow host specificity limits the number of filarial species that are of major medical or veterinary importance. Wuchereria bancrofti, Brugia malayi and B. timori are the main causes of human lymphatic filariasis, an often debilitating infection that threathens the well-being of perhaps 300 million people living in tropical and subtropical areas around the world.1Onchocerca volvulus is the second leading cause of blindness worldwide, particularly in subsaharan Africa where “River Blindness” constitutes a major obstacle to economic development.2 Four other filarial species, Loa loa, Dipetalonema perstans, D. streptocerca, and Mansonella ozzardi, cause relatively benign infections in some parts of Africa and/or Central and South America.3 Filarial infections are also widespread among domestic animals. Several species of Onchocerca infect cattle and horses on all continents. Dirofilaria immitis is rare in Africa, but is a common parasite of dogs in warm climates elsewhere. B. pahangi infects cats throughout Southeast Asia. Setaria digitata is widespread among cattle, buffaloes and zebu in the Far East and northern Japan.4–6
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].
Development of a recombinant vaccine against human onchocerciasis
Published in Expert Review of Vaccines, 2021
David Abraham, John Graham-Brown, Darrick Carter, Sean A. Gray, Jessica A. Hess, Benjamin L. Makepeace, Sara Lustigman
Long the focus of efforts to alleviate morbidity and lost productivity, onchocerciasis has been identified by the World Health Organization as a potential candidate for global elimination through mass drug administration (MDA) of the donated drug ivermectin (IVM) (Mectizan®) [6–8]. This plan began in the 1990’s as the ‘Onchocerciasis Elimination in the Americas’ and later by the ‘African Programme for Onchocerciasis Control’ (APOC) in 1995 with a World Health Assembly goal to establish community-based sustainable treatments of 50 million people in 19 African countries having meso- and hyper-endemicity by 2010 [7,9]. In 2015, the mission of onchocerciasis elimination for Africa was passed from APOC to its successor, the Expanded Special Programme for the Elimination of Neglected Tropical Diseases [10]. Addition of vegetation ‘slash and clear’ for vector control, as a supplement to MDA, has been proposed as an adjunct to accelerate elimination of onchocerciasis [11]. However, numerous and formidable technical and logistical obstacles must still be overcome before the ambitious goal of elimination by 2030 can be achieved in Africa [9,12]. These include (1) MDA of IVM cannot be used in 11 Central African countries co-endemic with Loa loa infections due to the risk of severe adverse events [13–16]; (2) The few drugs active against the adult stage of the parasite are not used for MDA, and IVM, as well as the recently approved drug moxidectin, are only effective against microfilariae [17]; (3) The practical complication of treating people for 14 to 35 years compounds the difficulty of implementing the plan [7,8]; (4) Experimental studies indicate that susceptibility to reinfection may increase after treatment, further complicating the disruption of the transmission cycle [18–20]; and finally (5) The potential emergence of IVM-resistant O. volvulus, may limit the long-term effectiveness of MDA and, in time, undermine all of the gains achieved by onchocerciasis control programs [21–29]. Originally developed for veterinary use, IVM was re-purposed for use as a microfilaricidal drug in humans, initially to great effect [30,31]. While current evidence for IVM resistance in O. volvulus is far from definitive, it is quite clear that sub-optimal responses to IVM in the treatment of river blindness have been identified, in particular, as manifested by faster rates of microfilarial skin repopulation linked to decreased effects of IVM on female worm fecundity [32]. It should be noted that IVM was first used for many years to prevent heartworm disease caused by the filarial parasite Dirofilaria immitis in domestic dogs and cats, but it has been demonstrated that IVM-resistant D. immitis is already circulating in the United States [33]. Complicating the challenges with relying only on MDA with IVM is that IVM is not administered to children under 5 years old and a macrofilaricidal drug, doxycycline, cannot be given to children under 9 thus limiting the indications for these two drugs. In addition, doxycycline requires 6 weeks of treatment to be effective which further diminishes its utility [34]. Thus, children are not only vulnerable to infection but become reservoirs for transmission [35].
Related Knowledge Centers
- Anopheles
- Culex
- Dirofilariasis
- Parasitism
- Pulmonary Artery
- Lung
- Heart Failure
- Filarioidea
- Host
- Mosquito