Effects of Host and Vector Diversity on Disease Dynamics

Abstract

Disease dynamics are influenced by a number of factors including weather change, density of the population, and the relationships of different species with one another. It was also found however that number and vector variety can also have a major impact on disease dynamics. Research on both of these variables has not been as considerable as it ought to be considering the result they have. The research done on coordinator and vector variety is provided here concerning gather the info and show the gaps of knowledge present. Most of all this review shows the issues surrounding this subject matter with conflicting evidence from different studies and it illustrates the actual fact that what pertains to one varieties of variety, vector, or pathogen might not automatically be generally suitable generally.

Introduction

An infectious disease event contains at least two varieties interacting which will be the pathogen and the variety; however in cases of vector sent diseases a 3rd types, the vector, also participates the infection (Keesing et al. , 2006). Vectors are usually arthropods but can also include rodents or even areas which may be contaminated by the pathogen (Lemon & Institute of Medication. Forum on Microbial Dangers, 2008). Species diversity in all of the different periods of the infection make a difference disease dynamics and in this review the evaluation of this impact is shown.

Host Diversity

Different pathogens were found to be influenced differently as varieties richness rises (Miller & Huppert, 2013). A number of studies have showed that when kinds variety is increased in an ecosystem the pathogen large quantity lessens (Schmidt & Ostfeld, 2001; Ezenwa et al. , 2006). That is due to dilution impact hypothesis, which claims that by increasing the number of species there is a lower likelihood that the vector will infect a susceptible host in addition to a lower likelihood that the vector will uptake the pathogen producing a lower disease risk for the ecosystem. This is adapted from the concept of zooprophylaxis where it was argued that livestock could be positioned around human being settlements in order to divert the vectors from humans (Keesing et al. , 2006). The hypothesis also suggests that even in the case of multi-host pathogens an increase in diversity will still result in lowered disease risk. This is based on host competence where different hosts have different uptake success of the pathogen and therefore the pathogen will not be in a position to infect as many people due to its lower succesfull (Ostfeld et al. , 2008).

However on the other side you can find research exhibiting that occasionally pathogen abundance increased with number diversity. For example regarding Lyme disease (Ostfeld & Keesing, 2000) proved that as bird species richness escalates the large quantity of the pathogen boosts as well. This was further investigated by (Reduction et al. , 2009) where they disproved the hypothesis that varieties richness has a negative correlation with the plethora of the western Nile computer virus (WNV). While studying the consequences of zooprophylaxis (Saul, 2003) revealed that the increase of people supplies the mosquitoes with a lower search time when foraging thus increasing their survival rate, essentially negating the positive effects of the dilution impact.

When a new species is introduced to an ecosystem spillover of an illness may occur. This is because the new species brings in a fresh pathogen and therefore increases the visibility of native kinds compared to that pathogen. The new species can also become a site for creation of new strains of the pathogen which may result in the successful changeover of the pathogen in one host to some other (Parrish et al. , 2008). However even if a fresh species will not present a pathogen it could become a tank for the pathogen already present in the ecosystem thus again increasing the overall disease risk (Poulin et al. , 2011).

Inter-species host diversity is not the one factor in relation to diversity principles. Intra-species variety which is the genetic diversity of the populace also influences disease dynamics. (Lively, 2010) produced a model that exhibited that the greater diverse the genetic composition of a human population is the less result a pathogen will have. The model was run under the assumption that each sponsor genotype is susceptible to only one pathogen strain while immune to the others. A similar model was done with livestock populations by (Springbett et al. , 2003) that got similar results thus reinforcing the hypothesis.

This hypothesis comes from research done in crops where empirical evidence was collected that as genetic diversity increases in a population then your susceptibility of the population to a specific pathogen decreases (Mundt et al. , 2011). Research was also done in bacteria again displaying that as the hereditary variety of the sponsor bacteria Pseudomonas phaseolicola rises then the great quantity of the bacteriophage О6 boosts. The experiment revealed that with only 50% of the population vunerable to this phage then your great quantity of the phage lessens almost tenfold (Dennehy et al. , 2007).

These tests are being put on animals nonetheless it is proving more difficult because you can't manipulate hereditary variety so easily in animals with regards to plants and bacterias. An test out water fleas, Dapnia magna showed that populations that had a higher hereditary diversity acquired lower infection degrees of the parasite Octosporea bayeri (Altermatt & Ebert, 2008).

This hypothesis is also predicated on the concepts brought up earlier which are the dilution effect brought on by increased variety of hosts and also on the competence of hosts with specific genotypes. Which means that again for some diseases the hypothesis may be suitable however other types of pathogens may well not have the same mechanisms thus the hypothesis can be rejected (Ostfeld & Keesing 2012).

Vector Diversity

Even though it is known that vector diversity plays an important role in disease dynamics it has not been researched all the and it is poorly understood. Almost all research done on vector variety is performed for plant pathogen taking vectors. It is because plants allow for large controlled tests where different hosts, vector or pathogen strains can be examined (Lemon 2008). A lot of the research done on vectors having dog diseases are in hereditary sequencing so that the genes that permit the pathogen to complete its life cycle in the vector are found and taken out (Sinkins 2007). However by firmly taking into consideration the factors that influence disease dynamics in plant life we can try to apply them to pet animal pathogens.

One of the ways in which vector diversity affects the condition dynamics is just how that transmitting actually occurs. For bugs, pathogens can be sent by the pathogen going through the foregut or other organs of the vectors body, thus enabling a larger pathogen persistence in the vector or they can be mechanically transmitted where the pathogen is not actually adopted by the vector but is on its mouthparts thus enabling transmission for a restricted timeframe. So a pathogen has its persistence in the vector human population dependent on the varieties of the vector (Grey & Banerjee 1999). The life span history of the types also takes on an important role in disease dynamics. Univoltine vectors just have one era per season while multivoltine types have more than two years per year. This means that the condition dynamics are firmly correlated to vector life record since multivoltine varieties can generate a larger population that can more easily spread a disease in an ecosystem. The WNV for example can be transmitted by univoltine but also by multivoltine species allowing for different disease dynamics depending on structure of vector populations (Crans 2004).

Disease dynamics may also be influenced by intra-species diversity in the manner that vectors with different genotypes or developmental stages can uptake the trojan differently. This means that a lot of people may be more susceptible to the disease, which is the same concept as web host competence. For example young individuals may not be as productive in transmitting the pathogen as individuals are. So in a society of vector types the disease transmission may change over time as the genotype of the population as a whole changes or as the populace changes demographics i. e. the population possessed more young individuals that are now parents hence changing the condition transmission rates(Ostfeld, keesing publication 2008).

Diversity can also happen in conditions of behaviour. Different kinds have different variety preferences meaning that the range of hosts is only tied to the feeding range of the vector. So launch of new vector species that can transmit a pathogen can result in a rise in the condition prevalence because the new vector may feed on different hosts thus allowing the pathogen to infect other varieties not previously afflicted. It was discovered that feeding preferences play an essential role in the case of WNV where in fact the authors discovered that it was the most important factor regarding disease transmitting (Simpson et al 2012).

As discussed earlier we can use these instances from plants to study vector diversity effect on animal diseases. Nonetheless it is important to understand that even though there are a great number of similarities between vector-borne animal and seed disease the populace there are factors that impact the diseases in a different way including host populace activity and the distinctions between pet animal and plant immune system systems (Ostfeld keesing reserve 2008).

Conclusion

It is obvious that host and vector diversity play an important role in disease dynamics so that as shown in this review higher variety can mean either an increase or a loss of disease transmission. Also diversity is present in different aspects of an ecosystem including inter-species, intra-species and behavioural diversity. It is required to research the effects of variety in disease dynamics especially in vector diversity for dog pathogens since they are extremely inadequately examined. As more info is found on wildlife disease dynamics and the factors that have an effect on them, we can prepare strategies for managing the get spread around of an illness and use them in instances of an epidemic. This allows us to effectively cope with disease outbreaks both in the wild but also we can use these approaches for captive pets where disease is released thus enabling the population to recuperate.

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