How to identify and treat common bites and stings.

A thorough history and physical are key to proper diagnosis and treatment following a patient's encounter with an insect, arachnid, or other arthropod.

Acanthocytosis and brain damage in area postrema and choroid plexus: Description of novel signs of Loxosceles apachea envenomation in rats.

Loxocelism is a neglected medical problem that depends on its severity, can cause a cutaneous or viscero-cutaneous syndrome. This syndrome is characterized by hemostatic effects and necrosis, and the severity of the loxoscelism depends on the amount of venom injected, the zone of inoculation, and the species. In the Chihuahuan desert, the most abundant species is L. apachea. Its venom and biological effects are understudied, including neurological effects. Thus, our aim is to explore the effect of this regional species of medical interest in the United States-Mexico border community, using rat blood and central nervous system (CNS), particularly, two brain structures involved in brain homeostasis, Area postrema (AP) and Choroid plexus (PC). L. apachea specimens were collected and venom was obtained. Different venom concentrations (0, 0.178 and 0.87 µg/g) were inoculated into Sprague-Dawley rats (intraperitoneal injection). Subsequently, blood was extracted and stained with Wright staining; coronal sections of AP were obtained and stained with Hematoxylin-Eosin (HE) staining and laminin γ immunolabelling, the same was done with CP sections. Blood, AP and CP were observed under the microscope and abnormalities in erythrocytes and fluctuation in leukocyte types were described and quantified in blood. Capillaries were also quantified in AP and damage was described in CP. L. apachea venom produced a segmented neutrophil increment (neutrophilia), lymphocyte diminishment (leukopenia) and erythrocytes presented membrane abnormalities (acanthocytosis). Extravasated erythrocytes were observed in HE stained sections from both, AP and CP, which suggest that near to this section a hemorrhage is present; through immunohistofluorescence, a diminishment of laminin γ was observed in AP endothelial cells and in CP ependymal cells when these structures were exposed to L. apachea venom. In conclusion, L. apachea venom produced leukopenia, netrophilia and acanthocytosis in rat peripheral blood, and also generated hemorrhages on AP and CP through degradation of laminin γ.

A rare finding of mites (Arachnida: Acari: Leeuwenhoekiidae) parasitising a whip spider (Arachnida: Amblypygi: Charinidae).

Twelve larvae of unidentified species of Odontacarus Ewing, 1929 (Acari: Leeuwenhoekiidae) were found parasitising an adult male whip spider Charinus brasilianus Weygoldt (Charinidae) in Santa Teresa, mountainous region of Espirito Santo state, southeastern Brazil. These larvae occurred in the intersegmental membrane of prosoma and legs. This is the first report of ectoparasitic mites infecting a charinid whip spider and the first record of leeuwenhoekiid mites parasitising an invertebrate host. We suggest that future studies are essential to understand the reasons why these events of parasitism are so rare in the order Amblypygi.

Wolbachia, sex ratio bias and apparent male killing in the harlequin beetle riding pseudoscorpion.

Bacterial endosymbionts that manipulate host reproduction are now known to be widespread in insects and other arthropods. Since they inhabit the cytoplasm and are maternally inherited, these microorganisms can enhance their fitness by biasing host sex ratio in favour of females. At its most extreme, sex ratio manipulation may be achieved by killing male embryos, as occurs in a number of insect species. Here, we provide evidence for the first case of male killing by a tetracycline-sensitive microbe in pseudoscorpions. Using a combination of inheritance studies, antibiotic treatment and molecular assays, we show that a new strain of Wolbachia is associated with extreme female bias in the pseudoscorpion, Cordylochernes scorpioides. In a highly female-biased line, sex ratio distortion was maternally inherited, and occurred in conjunction with a high rate of spontaneous abortion and low reproductive success. Antibiotic treatment cured females of the Wolbachia infection, restored offspring sex ratio to 1:1, and significantly enhanced female reproductive success. The discovery of apparent male-killing in C. scorpioides is of interest because pseudoscorpions are viviparous. Theory predicts that male killing should be favoured, if male death enhances the fitness of infected female siblings. In a live-bearing host, reallocation of maternal resources from dead male embryos to their sisters provides a direct, physiological mechanism through which fitness compensation could favour male killing by cellular endosymbionts. Our results suggest, however, that fitness compensation and the spread of male-killing endosymbionts may be undermined by a high rate of spontaneous abortion in infected females of this viviparous arthropod.

Analysis of the phenotypic effects of B chromosomes in a natural population of Metagagrella tenuipes (Arachnida: Opiliones).

Phenotypic effects of B chromosomes in a natural population of Metagagrella tenuipes (Arachnida: Opiliones) were studied. Mean number of Bs per individual in the population studied was 6.0, and remained stable during two successive summers of 1997 and 1998. In contrast to the number of B chromosomes, ratios between individuals possessing odd and those possessing even numbers of Bs changed during both collection seasons: the proportion of harvestmen with an even number of Bs decreased from June-July to October-November. A possible reason for this may be a difference in susceptibility to parasites between B-odd and B-even harvestmen. In the group of B-even individuals the percentage of infected harvestmen in the June-July samples was much higher compared to the B-odd group. In addition, the infection rate in the B-even group decreased more sharply than among B-odd harvestmen. In the group of B-even harvestmen infection was associated with reduced body size, whereas no such association was found among B-odd harvestmen. In the group of B-even individuals there was a U-shaped relationship between number of Bs and the probability of being infected by parasites, and an inverted-U-shaped relationship between body size and number of Bs. No such associations were found in the group of B-odd harvestmen. Seasonal selection is suggested to be a main factor contributing to the B-chromosome polymorphism in M. tenuipes.

Attachment sites and frequency distribution of erythraeid mites, Leptus indianensis (Acari: Prostigmata), ectoparasitic on harvestmen, Leiobunum formosum (Opiliones).

Host attachment sites and frequency distribution of parasitism were investigated for the larval erythraeid mite Leptus indianensis parasitising a sample of 500 harvestmen. Leiobunum formosum in Tennessee, USA. A significant difference was found in the number of mites attached to different body segments of the harvestmen with the greatest number of mites attached to femurs I-IV. Scanning electron microscopy revealed that the mites attached to smooth areas of the host integument between rows of stout setae. The frequency distribution of mites parasitising the harvestman population was highly clumped (Coefficient of Dispersion = 3.34) with a relatively small number of hosts being parasitised by most of the mites.