scholarly journals Past and future perspectives on mathematical models of tick-borne pathogens

Parasitology ◽  
2015 ◽  
Vol 143 (7) ◽  
pp. 850-859 ◽  
Author(s):  
R. A. NORMAN ◽  
A. J. WORTON ◽  
L. GILBERT
Keyword(s):  
Life Cycle ◽  
Mathematical Models ◽  
Environmental Conditions ◽  
Current Knowledge ◽  
Habitat Type ◽  
Spatial Models ◽  
Host Population ◽  
Complex Life Cycle ◽  
System Maps ◽  
Blood Meals

SUMMARYTicks are vectors of pathogens which are important both with respect to human health and economically. They have a complex life cycle requiring several blood meals throughout their life. These blood meals take place on different individual hosts and potentially on different host species. Their life cycle is also dependent on environmental conditions such as the temperature and habitat type. Mathematical models have been used for the more than 30 years to help us understand how tick dynamics are dependent on these environmental factors and host availability. In this paper, we review models of tick dynamics and summarize the main results. This summary is split into two parts, one which looks at tick dynamics and one which looks at tick-borne pathogens. In general, the models of tick dynamics are used to determine when the peak in tick densities is likely to occur in the year and how that changes with environmental conditions. The models of tick-borne pathogens focus more on the conditions under which the pathogen can persist and how host population densities might be manipulated to control these pathogens. In the final section of the paper, we identify gaps in the current knowledge and future modelling approaches. These include spatial models linked to environmental information and Geographic Information System maps, and development of new modelling techniques which model tick densities per host more explicitly.

scholarly journals Phenology of Promestosoma boggianii (Diplopoda: Polydesmida: Paradoxosomatidae) in a Neotropical floodplain

2018 ◽  
Vol 35 ◽  
pp. 1-8 ◽  
Author(s):  
Lorhaine Santos Silva ◽  
Tamaris Gimenez Pinheiro ◽  
Marinêz Isaac Marques ◽  
Leandro Dênis Battirola
Keyword(s):  
Life Cycle ◽  
Environmental Conditions ◽  
Habitat Type ◽  
High Water ◽  
Extreme Conditions ◽  
Pitfall Traps ◽  
Stages Of Development ◽  
Seasonal Flood ◽  
Neotropical Floodplain ◽  
Hydrological Cycles

Studies that address biodiversity and its supporting mechanisms in different ecosystems are fundamental to understanding the relationships between species and the prevailing environmental conditions within each habitat type. This study presents information on the phenology of Promestosomaboggianii (Silvestri, 1898) and its association with seasonal flood and dry events in a floodplain of Mato Grosso’s northern Pantanal region, Brazil. Sampling was carried out in three areas located between the Bento Gomes and Cuiabá rivers, on the Porto Cercado Road, Poconé-MT. Each sample area was composed of two treatments: (I) floodable habitats and (NI) non-floodable habitats. Three quadrats (10 x 10 m) were established within each treatment, with sampling carried out using pitfall traps and mini-Winkler extractors during the dry season, rising water, high water and receding water phases for the duration of two hydrological cycles within the Pantanal (2010/2011 and 2011/2012). A total of 295 P.boggianii individuals were sampled at different stages of development (except stages I and II), distributed between the rising water (209 ind., 70.8%), dry (76 ind., 25.8%) and receding water (10 ind., 3.4%) seasons. No specimens were sampled during the high water season. The higher abundances recorded between the dry and rising water seasons, primarily at early stages of development, indicate that P.boggianii is characterized as a univoltine species in these habitats. The data demonstrate that individuals of P.boggianii were more abundant in floodable habitats. In addition, the results show that the life cycle of this diplopod is sinchronized to the seasonal nature of this floodable environment, as a strategy to survive the extreme conditions of terrestrial and aquatic phases Brazil’s northern Pantanal region.

scholarly journals Malaria parasite egress at a glance

2021 ◽  
Vol 134 (5) ◽  
pp. jcs257345
Author(s):  
Michele S. Y Tan ◽  
Michael J. Blackman
Keyword(s):  
Life Cycle ◽  
Malaria Control ◽  
Cyst Wall ◽  
Malaria Parasite ◽  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Complex Life Cycle ◽  
Intracellular Pathogens ◽  
Parasite Egress ◽  
Intracellular Vacuole

ABSTRACTAll intracellular pathogens must escape (egress) from the confines of their host cell to disseminate and proliferate. The malaria parasite only replicates in an intracellular vacuole or in a cyst, and must undergo egress at four distinct phases during its complex life cycle, each time disrupting, in a highly regulated manner, the membranes or cyst wall that entrap the parasites. This Cell Science at a Glance article and accompanying poster summarises our current knowledge of the morphological features of egress across the Plasmodium life cycle, the molecular mechanisms that govern the process, and how researchers are working to exploit this knowledge to develop much-needed new approaches to malaria control.

Ultrastructural analysis of “Sensory” surface nerve endings and “putative” neurotransmitter sites in Schistosoma mansoni Miracidia

1989 ◽  
Vol 47 ◽  
pp. 962-963
Author(s):  
Betty Ruth Jones ◽  
Steve Chi-Tang Pan
Keyword(s):  
Nervous System ◽  
Life Cycle ◽  
Schistosoma Mansoni ◽  
Snail Host ◽  
Complex Life Cycle ◽  
Rational Approach ◽  
Effective Control ◽  
The Social ◽  
Social And Economic Development ◽  
Basic Biology

INTRODUCTION: Schistosomiasis has been described as “one of the most devastating diseases of mankind, second only to malaria in its deleterious effects on the social and economic development of populations in many warm areas of the world.” The disease is worldwide and is probably spreading faster and becoming more intense than the overall research efforts designed to provide the basis for countering it. Moreover, there are indications that the development of water resources and the demands for increasing cultivation and food in developing countries may prevent adequate control of the disease and thus the number of infections are increasing.Our knowledge of the basic biology of the parasites causing the disease is far from adequate. Such knowledge is essential if we are to develop a rational approach to the effective control of human schistosomiasis. The miracidium is the first infective stage in the complex life cycle of schistosomes. The future of the entire life cycle depends on the capacity and ability of this organism to locate and enter a suitable snail host for further development, Little is known about the nervous system of the miracidium of Schistosoma mansoni and of other trematodes. Studies indicate that miracidia contain a well developed and complex nervous system that may aid the larvae in locating and entering a susceptible snail host (Wilson, 1970; Brooker, 1972; Chernin, 1974; Pan, 1980; Mehlhorn, 1988; and Jones, 1987-1988).

scholarly journals Foamy Viruses, Bet, and APOBEC3 Restriction

Viruses ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 504
Author(s):  
Ananda Ayyappan Jaguva Vasudevan ◽  
Daniel Becker ◽  
Tom Luedde ◽  
Holger Gohlke ◽  
Carsten Münk
Keyword(s):  
Current Knowledge ◽  
Regulatory Protein ◽  
Host Population ◽  
Life Cycles ◽  
Restriction Factors ◽  
Host Restriction ◽  
Open Questions ◽  
Foamy Viruses ◽  
Natural Hosts ◽  
Hiv 1

Non-human primates (NHP) are an important source of viruses that can spillover to humans and, after adaptation, spread through the host population. Whereas HIV-1 and HTLV-1 emerged as retroviral pathogens in humans, a unique class of retroviruses called foamy viruses (FV) with zoonotic potential are occasionally detected in bushmeat hunters or zookeepers. Various FVs are endemic in numerous mammalian natural hosts, such as primates, felines, bovines, and equines, and other animals, but not in humans. They are apathogenic, and significant differences exist between the viral life cycles of FV and other retroviruses. Importantly, FVs replicate in the presence of many well-defined retroviral restriction factors such as TRIM5α, BST2 (Tetherin), MX2, and APOBEC3 (A3). While the interaction of A3s with HIV-1 is well studied, the escape mechanisms of FVs from restriction by A3 is much less explored. Here we review the current knowledge of FV biology, host restriction factors, and FV–host interactions with an emphasis on the consequences of FV regulatory protein Bet binding to A3s and outline crucial open questions for future studies.

Digestion in the tsetse fly Glossina morsitans Westw.: the effect of feeding field-caught flies on guineapigs in the laboratory

1967 ◽  
Vol 57 (3) ◽  
pp. 447-450 ◽  
Author(s):  
P. A. Langley
Keyword(s):  
Natural Environment ◽  
Environmental Conditions ◽  
Tsetse Fly ◽  
Rapid Loss ◽  
Glossina Morsitans ◽  
The Third ◽  
Laboratory Conditions ◽  
Effect Of Feeding ◽  
Blood Meals

It has been shown that adults of Glossina morsitans Westw. that have fed from a bait ox in their natural environment digest their blood meals more rapidly than others that have emerged and been fed in the laboratory, even when both are maintained under identical environmental conditions after feeding.In further experiments with G. morsitans in Rhodesia, flies caught in the field and fed in the laboratory were found to lose their ability to digest their meals rapidly. Measurements, made throughout three hunger cycles, of the rate of digestion, as reflected in the rate of excretion, of blood meals by field-caught flies fed on guineapigs in the laboratory showed that this was not significantly different from that of the normal, flied-fed flies during the first two hunger cycles but that during the third it fell to a level comparable to that of flise that emerged and were fed in the laboratory.It is concluded that whatever may be the events that condition the field flies to digest their meals rapidly in the natural environment, these are repeated with the ingestion of each meal, and that laboratory conditions cause a rapid loss of this greater digestive capability.

The Output of First Stage Larvae by Cats Infested with Aelurostrongylus abstrusus

1968 ◽  
Vol 42 (3-4) ◽  
pp. 295-298 ◽  
Author(s):  
J. M. Hamilton ◽  
A. W. McCaw
Keyword(s):  
Life Cycle ◽  
Great Britain ◽  
Intermediate Host ◽  
World Wide ◽  
Wide Distribution ◽  
Clinical Disease ◽  
Complex Life Cycle ◽  
Patent Period ◽  
Aelurostrongylus Abstrusus

Aelurostrongylus abstrusus, the lungworm of the cat, has a world wide distribution and has been reported from countries as far apart as America, Great Britain and Palestine. It has a complex life cycle insofar as a molluscan intermediate host is essential and it is possible that auxiliary hosts also play an important part. In Britain, the incidence of active infestation of cats with the parasite has been recorded as 19·4% (Lewis, 1927) and 6·6% (Hamilton, 1966) but the latter author found that, generally, the clinical disease produced by the parasite was of a mild nature. It is known that the average patent period of the infestation in the cat is 8–13 weeks and it seems likely that, in that time, a considerable number of first stage larvae would be evacuated. Information on that point is not available and the object of the following experiment was to ascertain the number of larvae produced by cats during the course of a typical infestation.

Autonomy and integration in complex parasite life cycles

Parasitology ◽  
2016 ◽  
Vol 143 (14) ◽  
pp. 1824-1846 ◽  
Author(s):  
DANIEL P. BENESH
Keyword(s):  
Life Cycle ◽  
Holistic Approach ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Functional Specialization ◽  
Life Stages ◽  
Free Living ◽  
New Host ◽  
Complex Life Cycles ◽  
Life Cycle Stages

SUMMARYComplex life cycles are common in free-living and parasitic organisms alike. The adaptive decoupling hypothesis postulates that separate life cycle stages have a degree of developmental and genetic autonomy, allowing them to be independently optimized for dissimilar, competing tasks. That is, complex life cycles evolved to facilitate functional specialization. Here, I review the connections between the different stages in parasite life cycles. I first examine evolutionary connections between life stages, such as the genetic coupling of parasite performance in consecutive hosts, the interspecific correlations between traits expressed in different hosts, and the developmental and functional obstacles to stage loss. Then, I evaluate how environmental factors link life stages through carryover effects, where stressful larval conditions impact parasites even after transmission to a new host. There is evidence for both autonomy and integration across stages, so the relevant question becomes how integrated are parasite life cycles and through what mechanisms? By highlighting how genetics, development, selection and the environment can lead to interdependencies among successive life stages, I wish to promote a holistic approach to studying complex life cycle parasites and emphasize that what happens in one stage is potentially highly relevant for later stages.

scholarly journals Dietary Choline Intake: Current State of Knowledge Across the Life Cycle

Nutrients ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1513 ◽  
Author(s):  
Alejandra Wiedeman ◽  
Susan Barr ◽  
Timothy Green ◽  
Zhaoming Xu ◽  
Sheila Innis ◽  
...  
Keyword(s):  
Life Cycle ◽  
Current Knowledge ◽  
Water Soluble ◽  
Food Sources ◽  
Soluble Form ◽  
Dietary Recommendations ◽  
Current State ◽  
Dietary Nutrient ◽  
Choline Intake ◽  
Dietary Choline

Choline, an essential dietary nutrient for humans, is required for the synthesis of the neurotransmitter, acetylcholine, the methyl group donor, betaine, and phospholipids; and therefore, choline is involved in a broad range of critical physiological functions across all stages of the life cycle. The current dietary recommendations for choline have been established as Adequate Intakes (AIs) for total choline; however, dietary choline is present in multiple different forms that are both water-soluble (e.g., free choline, phosphocholine, and glycerophosphocholine) and lipid-soluble (e.g., phosphatidylcholine and sphingomyelin). Interestingly, the different dietary choline forms consumed during infancy differ from those in adulthood. This can be explained by the primary food source, where the majority of choline present in human milk is in the water-soluble form, versus lipid-soluble forms for foods consumed later on. This review summarizes the current knowledge on dietary recommendations and assessment methods, and dietary choline intake from food sources across the life cycle.

scholarly journals 3 Tackling Demolition Waste – An en route to Sustainable Development

2018 ◽  
Vol 8 (1) ◽  
pp. 8
Author(s):  
Nadia Qamar ◽  
Ayesha Alam Khurram
Keyword(s):  
Sustainable Development ◽  
Life Cycle Assessment ◽  
Life Cycle ◽  
Environmental Conditions ◽  
Material Flow ◽  
Flow Analysis ◽  
Material Flow Analysis ◽  
Construction And Demolition Waste ◽  
Water Tank ◽  
Demolition Waste

In Pakistan, construction and demolition waste(CDW) is generated in voluminous amount each year. CDW iswidely ill-handled and ultimately fed to landfills causing harm tothe already alarming environmental conditions. In order tosearch for the solution of this drastic matter, a study was done,which is explained in this paper. This paper presents the studydone at a demolition site near Karachi, in Sindh while thedemolition works were being carried out. At the site there wereold barracks which were being demolished. Before the demolitionworks were commenced, the site was surveyed and structuralcomponents of the barracks were counted and their dimensionswere measured. When the demolition was over, the demolishedwaste was calculated which comprised of concrete and masonryrubble, steel round bars, steel doors, steel windows, steel ceiling,steel girders, steel main gate, and plastic water tank. This studyinterpreted that construction and demolition (C&D) works wereprogressing considering the works’ deadline and the clients’requirements but the ecosystem’s ecology and the environmentalhealth were not taken into account. Recommendations are madeto handle CDW properly throughout its lifecycle. Theserecommendations aim to provide technological and logicalsolutions to grip CDW. The recommendations include wastereduction and reusing waste, life cycle assessment and costing,environmental and economic impact, material flow analysis, andadvanced computerized-tools.

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