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The Parasite's Way of Life
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
As discussed in Chapter 1 and the historical overview, many parasites rely on vectors to achieve transmission. Parasites typically move between vector and host as the vector takes a blood meal. Most vectors are arthropods and the roster of parasites (eukaryotic, prokaryotic or viral) that rely on arthropod vector transmission is long. The Anopheles mosquitoes that transmit Plasmodium may be the best known example. Mosquitoes also serve as vectors for the transmission of those nematodes in the genera Wuchereria and Brugia that cause filariasis. Other well-known examples include tsetse flies (genus Glossina), which transmit sleeping sickness (caused by kinetoplast protozoa in the Trypanosoma brucei species complex), cone-nosed or kissing bugs, which transmit Chagas disease (caused by Trypanosoma cruzi), and sand flies, which transmit leishmaniasis. Other parasites such as apicomplexans in the genus Babesia rely on non-insect arthropods, specifically ticks in the genera Ixodes or Rhipicephalus. As we already noted in Chapter 1 (see Box 1.1) the importance of ticks as vectors is increasing due to climate change, habitat alteration and other human-induced changes in the environment. Relapsing fever, caused by the spirochete bacterium Borrelia miyamotoi, is just one example of a newly emerging disease, resulting in part from the range expansion and increasing density of its ixodid tick vectors.
The Parasitic Protozoa and Helminth Worms
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Human filariasis is caused by infections with several species of nematode worms, the females of which produce larvae that are released in the body of the host, often in the blood, until taken up by an arthropod vector. The most important manifestations are lymphatic filariasis and onchocerciasis. In lymphatic filariasis, caused by Wuchereria bancrofti, Brugia malayi, and Brugia timori and transmitted by mosquitoes, the adults live in the lymphatics, and the disease is characterized by lymphatic blockage resulting in swelling of the limbs, scrotum and other parts of the body causing the condition known as elephantiasis. In onchocerciasis, caused by Onchocerca volvulus and transmitted by blackflies belonging to the genus Simulium, the adults live in skin nodules, and the disease is characterized by blindness.
Infectious disease
Published in Kaji Sritharan, Jonathan Rohrer, Alexandra C Rankin, Sachi Sivananthan, Essential Notes for Medical and Surgical Finals, 2021
Kaji Sritharan, Jonathan Rohrer, Alexandra C Rankin, Sachi Sivananthan
Lymphatic filaria (Brugia malayi, Wuchereria bancrofti) are spread via mosquitoes and cause episodic fever and lymphangitis. Recurrent infections may cause fibrosis of the lymphatics (elephantiasis). Skin filaria include Onchocerca volvulus which is transmitted by the black fly and invades the skin and eyes (River blindness).
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
High infection rate of B. pahangi ranging from 95–100% in the laboratory strains of Mansonia crassipes Wulp, Ma. annulata and Anopheles barbirostris Wulp were observed in an earlier study [13]. However, Ae. albopictus showed no evidence of infection, whereas Ae. aegypti showed a small number of infective larvae. The results are comparable with our study in which none of the Ae. albopictus and Ae. aegypti were found positive. On the other hand, there were few experimental studies performed on other Brugia spp. against Ae. togoi. These studies found that Ae. togoi was a good experimental vector for both B. malayi and Brugia patei Buckley [16, 45; 17, 18, 46]. In addition, a study in Thailand [47] showed that Ae. togoi was a suitable laboratory vector for B. pahangi. Likewise, this finding parallels with our observation. Furthermore, Cx. quinquefasciatus was known to be resistant to B. pahangi in a study conducted in Kenya [48]. However, in our study, a L3 larva of B. pahangi was found in the head region of Cx. quinquefasciatus suggesting its potential as a vector for B. pahangi. It would be worthwhile to repeat these experiments by expanding the number of the mosquitoes in order to get a clearer picture on the infection rate and vector competency for B. pahangi in Cx. quinquefasciatus.
Helminths, hosts, and their microbiota: new avenues for managing gastrointestinal helminthiases in ruminants
Published in Expert Review of Anti-infective Therapy, 2020
Alba Cortés, James Rooney, Dave J. Bartley, Alasdair J. Nisbet, Cinzia Cantacessi
Together with increasing evidence of a fundamental role of the host gut flora in mechanisms of worm infection and establishment [9,10], several studies are beginning to elucidate the relative contribution of a ‘parasite microbiome’ to several physiological and reproductive processes of worms [60]. Indeed, endosymbionts have long been known to exert key functions in the biology of nematodes causing lymphatic filariasis in humans, i.e. Wuchereria bancrofti, Brugia malayi, and Brugia timori. These parasites harbor an obligate alpha-proteobacterial endosymbiont (Wolbachia) that is essential for worm development and survival, likely via the provision of pyrimidines [61]. The discovery that removal of Wolbachia using antibiotics led to effective control of filarial nematodes triggered a number of drug discovery programmes to develop novel, safe, and specific antiwolbachial drugs [62], as well as vaccines targeting Wolbachia antigens (e.g. [63]). One of these molecules, a Recombinase A of Wolbachia from B. malayi (wBmRecA), has shown some promise as a protective antigen against filarial infections; indeed, mice immunized with a recombinant version of wBmRecA and subsequently challenged with B. malayi microfilariae harbored 64.5% fewer infective third-stage (L3) larvae at postmortem examination than mice immunized with adjuvant only [63].
Lymphatic filariasis vaccine development: neglected for how long?
Published in Expert Review of Vaccines, 2021
Vivek P Chavda, Anjali Pandya, Sreeranjini Pulakkat, Moinuddin Soniwala, Vandana Patravale
The WHO estimated 36 million patients of hydrocoele and lymphedema as of May 2021, with 57% living in the South-East Asia Region (9 nations) and 37% living in the African Region (35 countries) [3]. The parasite is entirely missing from Europe, North America, and the Polar Regions. It vanished in the United States in the early 1900s, and only four nations are presently known to be endemic: Brazil, Haiti, Guyana, and the Dominican Republic. Almost 90% of infections are caused by W. bancrofti and the remainder by Brugia spp. It is spread by mosquitoes, including Anopheles, Aedes, Mansonia, and Culex [6]. Currently, 90% of LF is prevalent in Sub-Saharan Africa.