Trail Pheromone Disruption of Argentine Ant Trail Formation and Foraging

Trail pheromone disruption of invasive ants is a novel tactic that builds on the development of pheromonebased pest management in other insects. Argentine ant trail pheromone, (Z)-9-hexadecenal, was formulated as a microencapsulated sprayable particle and applied against Argentine ant populations in 400 m2 field plots in Hawai‘i Volcanoes National Park. A widely dispersed point source strategy for trail pheromone disruption was used. Traffic rates of ants in bioassays of treated filter paper, protected from rainfall and sunlight, indicated the presence of behaviorally significant quantities of pheromone being released from the formulation for up to 59 days. The proportion of plots, under trade wind conditions (2–3 m s−1), with visible trails was reduced for up to 14 days following treatment, and the number of foraging ants at randomly placed tuna-bait cards was similarly reduced. The success of these trail pheromone disruption trials in a natural ecosystem highlights the potential of this method for control of invasive ant species in this and other environments

Validation of a death assay for Angiostrongylus cantonensis larvae (L3) using propidium iodide in a rat model (Rattus norvegicus)

Angiostrongylus cantonensis is a pathogenic nematode and the cause of neuroangiostrongyliasis, an eosinophilic meningitis more commonly known as rat lungworm disease. Transmission is thought to be primarily due to ingestion of infective third stage larvae (L3) in gastropods, on produce, or in contaminated water. The gold standard to determine the effects of physical and chemical treatments on the infectivity of A. cantonensis L3 larvae is to infect rodents with treated L3 larvae and monitor for infection, but animal studies are laborious and expensive and also raise ethical concerns. This study demonstrates propidium iodide (PI) to be a reliable marker of parasite death and loss of infective potential without adversely affecting the development and future reproduction of live A. cantonensis larvae. PI staining allows evaluation of the efficacy of test substances in vitro, an improvement upon the use of lack of motility as an indicator of death. Some potential applications of this assay include determining the effectiveness of various anthelmintics, vegetable washes, electromagnetic radiation and other treatments intended to kill larvae in the prevention and treatment of neuroangiostrongyliasis

Altered Immune Responses in Rhesus Macaques Co-Infected with SIV and Plasmodium cynomolgi: An Animal Model for Coincident AIDS and Relapsing Malaria

BACKGROUND:Dual epidemics of the malaria parasite Plasmodium and HIV-1 in sub-Saharan Africa and Asia present a significant risk for co-infection in these overlapping endemic regions. Recent studies of HIV/Plasmodium falciparum co-infection have reported significant interactions of these pathogens, including more rapid CD4+ T cell loss, increased viral load, increased immunosuppression, and increased episodes of clinical malaria. Here, we describe a novel rhesus macaque model for co-infection that supports and expands upon findings in human co-infection studies and can be used to identify interactions between these two pathogens. METHODOLOGY/PRINCIPAL FINDINGS:Five rhesus macaques were infected with P. cynomolgi and, following three parasite relapses, with SIV. Compared to macaques infected with SIV alone, co-infected animals had, as a group, decreased survival time and more rapid declines in markers for SIV progression, including peripheral CD4+ T cells and CD4+/CD8+ T cell ratios. The naïve CD4+ T cell pool of the co-infected animals was depleted more rapidly than animals infected with SIV alone. The co-infected animals also failed to generate proliferative responses to parasitemia by CD4+ and CD8+ T cells as well as B cells while also having a less robust anti-parasite and altered anti-SIV antibody response. CONCLUSIONS/SIGNIFICANCE:These data suggest that infection with both SIV and Plasmodium enhances SIV-induced disease progression and impairs the anti-Plasmodium immune response. These data support findings in HIV/Plasmodium co-infection studies. This animal model can be used to further define impacts of lentivirus and Plasmodium co-infection and guide public health and therapeutic interventions

High prevalence of \u3ci\u3eAngiostrongylus cantonensis\u3c/i\u3e (rat lungworm) on eastern Hawai`i Island: A closer look at life cycle traits and patterns of infection in wild rats (\u3ci\u3eRattus\u3c/i\u3e spp.)

The nematode Angiostrongylus cantonensis is a zoonotic pathogen and the etiological agent of human angiostrongyliasis or rat lungworm disease. Hawai`i, particularly east Hawai`i Island, is the epicenter for angiostrongyliasis in the USA. Rats (Rattus spp.) are the definitive hosts while gastropods are intermediate hosts. The main objective of this study was to collect adult A. cantonensis from wild rats to isolate protein for the development of a blood-based diagnostic, in the process we evaluated the prevalence of infection in wild rats. A total of 545 wild rats were sampled from multiple sites in the South Hilo District of east Hawai`i Island. Adult male and female A. cantonensis (3,148) were collected from the hearts and lungs of humanely euthanized Rattus rattus, and R. exulans. Photomicrography and documentation of multiple stages of this parasitic nematode in situ were recorded. A total of 45.5% (197/433) of rats inspected had lung lobe(s) (mostly upper right) which appeared granular indicating this lobe may serve as a filter for worm passage to the rest of the lung. Across Rattus spp., 72.7% (396/545) were infected with adult worms, but 93.9% (512/545) of the rats were positive for A. cantonensis infection based on presence of live adult worms, encysted adult worms, L3 larvae and/or by PCR analysis of brain tissue. In R. rattus we observed an inverse correlation with increased body mass and infection level of adult worms, and a direct correlation between body mass and encysted adult worms in the lung tissue, indicating that larger (older) rats may have developed a means of clearing infections or regulating the worm burden upon reinfection. The exceptionally high prevalence of A. cantonensis infection in Rattus spp. in east Hawai`i Island is cause for concern and indicates the potential for human infection with this emerging zoonosis is greater than previously thought

High prevalence of Angiostrongylus cantonensis (rat lungworm) on eastern Hawai'i Island: A closer look at life cycle traits and patterns of infection in wild rats (Rattus spp.).

The nematode Angiostrongylus cantonensis is a zoonotic pathogen and the etiological agent of human angiostrongyliasis or rat lungworm disease. Hawai'i, particularly east Hawai'i Island, is the epicenter for angiostrongyliasis in the USA. Rats (Rattus spp.) are the definitive hosts while gastropods are intermediate hosts. The main objective of this study was to collect adult A. cantonensis from wild rats to isolate protein for the development of a blood-based diagnostic, in the process we evaluated the prevalence of infection in wild rats. A total of 545 wild rats were sampled from multiple sites in the South Hilo District of east Hawai'i Island. Adult male and female A. cantonensis (3,148) were collected from the hearts and lungs of humanely euthanized Rattus rattus, and R. exulans. Photomicrography and documentation of multiple stages of this parasitic nematode in situ were recorded. A total of 45.5% (197/433) of rats inspected had lung lobe(s) (mostly upper right) which appeared granular indicating this lobe may serve as a filter for worm passage to the rest of the lung. Across Rattus spp., 72.7% (396/545) were infected with adult worms, but 93.9% (512/545) of the rats were positive for A. cantonensis infection based on presence of live adult worms, encysted adult worms, L3 larvae and/or by PCR analysis of brain tissue. In R. rattus we observed an inverse correlation with increased body mass and infection level of adult worms, and a direct correlation between body mass and encysted adult worms in the lung tissue, indicating that larger (older) rats may have developed a means of clearing infections or regulating the worm burden upon reinfection. The exceptionally high prevalence of A. cantonensis infection in Rattus spp. in east Hawai'i Island is cause for concern and indicates the potential for human infection with this emerging zoonosis is greater than previously thought

Observed prevalence of adult rat lungworms (<i>Angiostrongylus cantonensis</i>) for multiple body mass categories in two species of wild rats (<i>Rattus exulans</i> and <i>R</i>. <i>rattus</i>) on east Hawai‘i Island.

<p>Results displayed are from rat individuals used in the GLM analysis only (n = 405; see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189458#pone.0189458.t002" target="_blank">Table 2</a>). Columns with different letters differ (P < 0.05). The star indicates significance could not be determined due to low sample size.</p

Map of trapping sites in east Hawai‘i Island.

<p>Refer to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189458#pone.0189458.t001" target="_blank">Table 1</a> for details of all site locations.</p

Images of multiple stages of <i>Angiostrongylus cantonensis</i> in situ.

<p><i>a</i>. Embryonated <i>A</i>. <i>cantonensis</i> eggs in the lung tissue of a rat (40X). <i>b</i>. <i>A</i>. <i>cantonensis</i> eggs that were located in the uterus of a female worm (40X). <i>c</i>. <i>A</i>. <i>cantonensis</i> L1 larvae in lung visualized by tissue squash (10X). <i>d</i>. <i>A</i>. <i>cantonensis</i> L1 larvae observed in rat feces (10x). <i>e</i>. Small black worms, later determined to be L3 <i>A</i>. <i>cantonensis</i> larvae observed in the rat’s lungs. <i>f</i>. The transition between the esophagus and intestine are clearly defined in <i>A</i>. <i>cantonensis</i> L3 larvae.</p

Summary of AICc (Akaike’s Information Criterion corrected for small sample size) model selection of rat lungworm (<i>Angiostrongylus cantonensis</i>) infection in rats (<i>Rattus</i> spp.) sampled on east Hawai‘i Island for five independent generalized linear model (GLM) analyses (A-E).

<p>(A) Prevalence of adult worms, (B) intensity of adult worms, (C) prevalence of encysted worms, (D) prevalence of third stage larvae in the lungs, (E) prevalence of granular lung lobes. Model factors include host characteristics (body mass, species, and sex) and sampling location (site); numbers preceding models indicate model rank within each analysis; k = number of parameters in the models.</p