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Parasites and Conservation Biology
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Monitoring the richness of ectoparasite species, particularly of host specific lice with simple direct life cycles, has been suggested as a valuable way to assess the impact of habitat fragmentation on bird species. The richness of the louse community on birds was shown to correlate with the size of forest habitats in southern China. Furthermore, in smaller patches of forests, some louse species were lost from some birds, suggesting that lice may go extinct even if their hosts can hang on. Loss of parasite species may provide a sensitive forewarning of impending population collapses of birds in small habitat patches, potentially an important indicator for wildlife managers to consider. Findings like these support the idea that smaller, isolated host populations support fewer parasite species, potentially increasing the risk of eventual coextinctions, namely the loss of both supporting host species and its dependent parasites, a topic we return to later.
Infestations and Bites
Published in Ayşe Serap Karadağ, Lawrence Charles Parish, Jordan V. Wang, Roxburgh's Common Skin Diseases, 2022
Overview: Human body louse due to Pediculosis corporis (Figure 9.5) is transmitted from person to person during conditions of overcrowding and poor hygiene. The adult louse is normally found in the seams of clothing and only transfer to the human body to take a blood meal, which it does several times a day. Body lice frequently lay eggs on clothing fibers on or near the seams.
Scabies and pediculosis
Published in Robert A. Norman, Geriatric Dermatology, 2020
Lice are arthropods belonging to the order Phthiraptera (wingless insects). They include the suborder Anoplura (sucking lice) and the families Pediculidae and Phthiriidae. Two species of lice infest humans, Pediculus humanus and Pthirus pubis (pubic louse). Pediculus humanus is divided into 2 subspecies, Pediculus humanus capitis (head louse) and Pediculus humanus corporis (body louse). These subspecies have identical morphology, although the body louse tends to be larger, and the subspecies are interfertile. Interestingly, their differences may represent a response to environment: head lice grown on the body acquire the characteristics of body lice and vice versa21. Pediculosis refers to infestation with any of these parasites. There are no free-living forms of these insects, and they cannot survive on other animals. Lice are host-specific, and dog lice cannot infest humans, nor will human lice survive on pets.
Larvicidal activity of Zinc oxide and titanium dioxide nanoparticles Synthesis using Cuscuta reflexa extract against malaria vector (Anopheles stephensi)
Published in Egyptian Journal of Basic and Applied Sciences, 2020
The larvae of An. stephensi were found highly susceptible to the TiO2 NPs. The first and fourth instar larvae have shown the 100% mortality after 48 h of exposure. Whereas, the second instar (LC50 10 ppm) and third instar (LC50 50 ppm) larvae were observed with their probit equations and 95% confidential limit, R2, chi-square, and p value after 48 h (Table 1). No mortality was observed in the control group. The larvicidal activity of titanium dioxide nanoparticles (TiO2 NPS) synthesized from the root aqueous extract of M. citrifolia against the larvae of An. stephensi, Ae. aegypti and Cx. quinquefasciatus has been assessed [17]. The biosynthesized TiO2 NPS showed maximum activity against the larvae of An. stephensi, Ae. aegypti and Cx. quinquefasciatus when compared to the aqueous extract of M. citrifolia. Similarly, the anti-parasitic activity of TiO2 NPs against the larvae of R. microplus, H. anatolicum anatolicum and H. bispinosa, fourth instar larvae of An. subpictus, and Cx. quinquefasciatus has been assessed by [16]. The maximum efficacy was observed in synthesized TiO2 NPs against the larvae of R. microplus, H. anatolicum anatolicum, H. bispinosa, An. subpictus, and Cx. quinquefasciatus with LC value of 28.56, 33.17, 23.81, 5.84, and 4.34 mg/L, respectively. Recently, the larvicidal and the pediculicidal activity of synthesized titanium dioxide nanoparticles (TiO2 NPs) using the leaf aqueous extract of V. negundo against the fourth instar larvae of the malaria vector, An. subpictus Grassi and filariasis vector, Cx. quinquefasciatus Say and the head louse, P. humanus capitis De Geer have been carried out by [18]. The maximum activity has been observed in the synthesized TiO2 NPs against An. subpictus, Cx. quinquefasciatus and lice, (LC50 = 7.52, 7.23, and 24.32 mg/L; χ2 = 0.161, 2.678, and 4.495; r2 = 0.663, 0.742, and 0.924), respectively.
How relevant are in vitro culture models for study of tick-pathogen interactions?
Published in Pathogens and Global Health, 2021
Cristiano Salata, Sara Moutailler, Houssam Attoui, Erich Zweygarth, Lygia Decker, Lesley Bell-Sakyi
Most pathogenic Rickettsia spp. must be handled at BSL3, posing particular problems for studies on tick-bacterial interactions. Thus, as with highly pathogenic viruses, such as CCHFV, tick cell cultures are a useful substitute for live, intact ticks enabling a range of studies at the cellular and molecular level. Growth of Rickettsia rickettsii, causative agent of Rocky Mountain spotted fever in humans, was compared in tick (DALBE3 and IDE2) and mammalian cell lines at temperatures between 28°C and 34°C; raising the incubation temperature induced expression of rickettsial proteins in infected tick cells possibly associated with pathogenicity for mammalian cells [152]. In the absence of a louse cell line, tick (ISE6) and insect (Sf9) cell lines were used as models to analyze the effect on the proteome of Rickettsia prowazekii, causative agent of louse-borne human epidemic typhus, of growth in arthropod and mammalian environments [153]. In this study, rickettsial stress response proteins were upregulated in both arthropod cell lines and in a murine cell line, compared to levels in bacteria grown in hen egg yolk sacs, indicating possible limitations of cell cultures to model the in vivo situation. Nevertheless, comparison of siRNA expression profiles and coding transcriptomes of R. prowazekii grown in tick (AAE2) and human cell lines revealed novel siRNAs unique to arthropod cells and evidence for alternative transcription start sites used by rickettsial genes depending on the host cell environment [154]. A review of tropism in a range of pathogenic Rickettsia spp. found that the arthropod host range in vivo was reflected in the susceptibility of tick and insect cell lines in vitro, with tick-borne spotted fever group Rickettsia generally growing better in tick cells and insect-borne typhus group Rickettsia growing better in insect cells [155]. A recent study using both tick cell lines and experimentally infected vector ticks found that while two Rickettsia parkeri proteins, RickA and Sca2, played a role in actin polymerization in tick cells in vitro and in vivo, their absence did not affect patterns of R. parkeri dissemination in live, intact ticks [156].