Measuring aggregation of parasites at different host population levels

Parasitology ◽  
1996 ◽  
Vol 112 (6) ◽  
pp. 581-587 ◽  
Author(s):  
T. Boulinier ◽  
A. R. Ives ◽  
E. Danchin
Keyword(s):  
Epidemiological Studies ◽  
Host Population ◽  
Rissa Tridactyla ◽  
Ixodes Uriae ◽  
Parasite Aggregation

SUMMARYParasites are generally found aggregated among hosts. In this paper we propose a method for measuring aggregation at different scales in the host population. We use the method to characterize the pattern of aggregation of the tick Ixodes uriae on chicks of its seabird host, the Kittiwake Rissa tridactyla. We found evidence of aggregation at the among-nest scale, but not among chicks within nests. This shows that the processes leading to aggregation occur at a higher scale than the nest. The methods we develop provide a way to compare parasite aggregation at different scales in a quantitative fashion and can be applied in a large number of epidemiological studies.

A synthetic review of notoedres species mites and mange

Parasitology ◽  
2016 ◽  
Vol 143 (14) ◽  
pp. 1847-1861 ◽  
Author(s):  
J. FOLEY ◽  
L. E. K. SERIEYS ◽  
N. STEPHENSON ◽  
S. RILEY ◽  
C. FOLEY ◽  
...  
Keyword(s):  
Close Contact ◽  
Systemic Disease ◽  
Severe Disease ◽  
Epidemiological Studies ◽  
Host Population ◽  
Disease Treatment ◽  
Notoedres Cati ◽  
Immunological Factors ◽  
Population Treatment ◽  
Notoedric Mange

SUMMARYNotoedric mange, caused by obligately parasitic sarcoptiform Notoedres mites, is associated with potentially fatal dermatitis with secondary systemic disease in small mammals, felids and procyonids among others, as well as an occasional zoonosis. We describe clinical spectra in non-chiropteran hosts, review risk factors and summarize ecological and epidemiological studies. The genus is disproportionately represented on rodents. Disease in felids and procyonids ranges from very mild to death. Knowledge of the geographical distribution of the mites is highly inadequate, with focal hot spots known for Notoedres cati in domestic cats and bobcats. Predisposing genetic and immunological factors are not known, except that co-infection with other parasites and anticoagulant rodenticide toxicoses may contribute to severe disease. Treatment of individual animals is typically successful with macrocytic lactones such as selamectin, but herd or wildlife population treatment has not been undertaken. Transmission requires close contact and typically is within a host species. Notoedric mange can kill half all individuals in a population and regulate host population below non-diseased density for decades, consistent with frequency-dependent transmission or spillover from other hosts. Epidemics are increasingly identified in various hosts, suggesting global change in suitable environmental conditions or increased reporting bias.

scholarly journals Heterogeneity in transmission parameters of hookworm infection within the baseline data from the TUMIKIA study in Kenya

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
James E. Truscott ◽  
Alison K. Ower ◽  
Marleen Werkman ◽  
Katherine Halliday ◽  
William E. Oswald ◽  
...  
Keyword(s):  
Negative Binomial ◽  
Positive Association ◽  
Monitoring And Evaluation ◽  
Host Population ◽  
Transmission Model ◽  
High Coverage ◽  
Study Region ◽  
Transmission Parameters ◽  
Parasite Aggregation ◽  
The Impact

Abstract Background As many countries with endemic soil-transmitted helminth (STH) burdens achieve high coverage levels of mass drug administration (MDA) to treat school-aged and pre-school-aged children, understanding the detailed effects of MDA on the epidemiology of STH infections is desirable in formulating future policies for morbidity and/or transmission control. Prevalence and mean intensity of infection are characterized by heterogeneity across a region, leading to uncertainty in the impact of MDA strategies. In this paper, we analyze this heterogeneity in terms of factors that govern the transmission dynamics of the parasite in the host population. Results Using data from the TUMIKIA study in Kenya (cluster STH prevalence range at baseline: 0–63%), we estimated these parameters and their variability across 120 population clusters in the study region, using a simple parasite transmission model and Gibbs-sampling Monte Carlo Markov chain techniques. We observed great heterogeneity in R0 values, with estimates ranging from 1.23 to 3.27, while k-values (which vary inversely with the degree of parasite aggregation within the human host population) range from 0.007 to 0.29 in a positive association with increasing prevalence. The main finding of this study is the increasing trend for greater parasite aggregation as prevalence declines to low levels, reflected in the low values of the negative binomial parameter k in clusters with low hookworm prevalence. Localized climatic and socioeconomic factors are investigated as potential drivers of these observed epidemiological patterns. Conclusions Our results show that lower prevalence is associated with higher degrees of aggregation and hence prevalence alone is not a good indicator of transmission intensity. As a consequence, approaches to MDA and monitoring and evaluation of community infection status may need to be adapted as transmission elimination is aimed for by targeted treatment approaches.

scholarly journals Biological, Epidemiological, and Clinical Aspects of Echinococcosis, a Zoonosis of Increasing Concern

2004 ◽  
Vol 17 (1) ◽  
pp. 107-135 ◽  
Author(s):  
Johannes Eckert ◽  
Peter Deplazes
Keyword(s):  
Alveolar Echinococcosis ◽  
Treatment Options ◽  
Epidemiological Studies ◽  
Host Population ◽  
Molecular Techniques ◽  
Clinical Aspects ◽  
Red Foxes ◽  
Larval Stages ◽  
Northern And Southern Hemispheres ◽  
Human Echinococcosis

SUMMARY Echinococcosis in humans is a zoonotic infection caused by larval stages (metacestodes) of cestode species of the genus Echinococcus. Cystic echinococcosis (CE) is caused by Echinococcus granulosus, alveolar echinococcosis (AE) is caused by E. multilocularis, and polycystic forms are caused by either E. vogeli or E. oligarthrus. In untreated cases, AE has a high mortality rate. Although control is essentially feasible, CE remains a considerable health problem in many regions of the northern and southern hemispheres. AE is restricted to the northern hemisphere regions of North America and Eurasia. Recent studies have shown that E. multilocularis, the causative agent of AE, is more widely distributed than previously thought. There are also some hints of an increasing significance of polycystic forms of the disease, which are restricted to Central and South America. Various aspects of human echinococcosis are discussed in this review, including data on the infectivity of genetic variants of E. granulosus to humans, the increasing invasion of cities in Europe and Japan by red foxes, the main definitive hosts of E. multilocularis, and the first demonstration of urban cycles of the parasite. Examples of emergence or reemergence of CE are presented, and the question of potential spreading of E. multilocularis is critically assessed. Furthermore, information is presented on new and improved tools for diagnosing the infection in final hosts (dogs, foxes, and cats) by coproantigen or DNA detection and the application of molecular techniques to epidemiological studies. In the clinical field, the available methods for diagnosing human CE and AE are described and the treatment options are summarized. The development of new chemotherapeutic options for all forms of human echinococcosis remains an urgent requirement. A new option for the control of E. granulosus in the intermediate host population (mainly sheep and cattle) is vaccination. Attempts are made to reduce the prevalence of E. multilocualaris in fox populations by regular baiting with an anthelmintic (praziquantel). Recent data have shown that this control option may be used in restricted areas, for example in cities, with the aim of reducing the infection risk for humans.

scholarly journals Isolation of an English uukuvirus (family Bunyaviridae)

1984 ◽  
Vol 93 (2) ◽  
pp. 313-316 ◽  
Author(s):  
S. M. Eley ◽  
P. A. Nuttall
Keyword(s):  
Virus Family ◽  
Rissa Tridactyla ◽  
Ixodes Uriae ◽  
North East ◽  
The Family ◽  
Louping Ill

SummaryA virus of the Uukuniemi serogroup was isolated from various organs of a moribund kittiwake (Rissa tridactyla) and from ticks (Ixodes uriae) that were feeding on the bird. The kittiwake was found on Marsden beach, north-east England. This is the first virus in the family Bunyaviridae to have been isolated in England and only the second English arthropodborne virus after louping ill virus, family Togaviridae (Smith & Varma, 1981). The possibility of infection of humans by uukuviruses is discussed.

Microhabitat preference and coexistence of ectoparasitic arthropods on Alaskan seabirds

1988 ◽  
Vol 66 (4) ◽  
pp. 987-997 ◽  
Author(s):  
Jae C. Choe ◽  
Ke Chung Kim
Keyword(s):  
Interspecific Interactions ◽  
Distribution Patterns ◽  
Dominant Group ◽  
Feather Mites ◽  
New Host ◽  
High Fecundity ◽  
Rissa Tridactyla ◽  
Ixodes Uriae ◽  
Common Murre ◽  
Body Regions

The population structure and distribution patterns of ectoparasitic arthropods on four species of Alaskan seabirds (common murre (Uria aalge), thick-billed murre (Uria lomvia), black-legged kittiwake (Rissa tridactyla), and red-legged kittiwake (Rissa brevirostris)) were studied and interspecific interactions were examined. In most ectoparasite populations on murres and kittiwakes, females predominated. This pattern may be attributable to differences in activity, behavior, and mortality between the sexes of the ectoparasites. Except for feather mites, adults of most ectoparasites were less abundant than immatures. The extremely high relative abundance of immature ticks was probably due to the high fecundity of these organisms and predation pressure. Distribution patterns of adults differed significantly from those of immatures in most louse and tick populations. Populations of lice (Quadraceps obliquus (Mjöberg), Quadraceps ornatus (Grube)) and ticks (Ixodes uriae White) on murres and kittiwakes were highly clumped. The degree of clumping was lower among ectoparasites on murres than among those on kittiwakes. Murres aggregate more and thus provide more opportunities for their ectoparasites to disperse to new host individuals. Ticks were the dominant group of ectoparasites in most body regions. On the wings, however, mites were much more abundant. The wings provided the largest surface area and supported the highest ectoparasite species diversity and population density. The louse and tick populations exhibited distinct patterns of spatial distribution on the host, largely as a result of their distinct preferences for certain microhabitats. However, close competition appears to occur between Q. obliquus and I. uriae on murres, and between the two feather mites, Alloptes (Alloptes) sp. and Laronyssus martini (Trouessart), on kittiwakes.

Parasite aggregations in host populations using a reformulated negative binomial model

2004 ◽  
Vol 78 (1) ◽  
pp. 57-61 ◽  
Author(s):  
P. Pal ◽  
J.W. Lewis
Keyword(s):  
Negative Binomial ◽  
Host Population ◽  
Distribution Model ◽  
Cumulative Probability ◽  
Heligmosomoides Polygyrus ◽  
Specific Level ◽  
Parasite Aggregation ◽  
High Degree ◽  
Binomial Function

AbstractThe negative binomial distribution model is reformulated and used to demarcate a host population at a specific level of infection by defining an attribute spanning a range of parasite aggregations. The upper limit of the range specifies the boundary for the classification of the host population and provides a technique to determine the cumulative probability at any level of parasite infection to a high degree of accuracy. This approach also leads to the evaluation of thekparameter, i.e. an inverse measure of dispersion of parasite aggregation, for each fraction of the host population with a discrete level of infection. The basic mathematical premise of the negative binomial function is unaltered in developing this reformulation which was applied to data on the distribution of the trichostrongylid nematodeHeligmosomoides polygyrusin populations of the field mouse,Apodemus sylvaticus.

The activity periods and life-cycle of the tick Ixodes uriae (Acari: Ixodidae) in relation to host breeding strategies

Parasitology ◽  
1996 ◽  
Vol 112 (6) ◽  
pp. 571-580 ◽  
Author(s):  
T. R. Barton ◽  
M. P. Harris ◽  
S. Wanless ◽  
D. A. Elston
Keyword(s):  
Life Cycle ◽  
Adult Female ◽  
Feeding Activity ◽  
Seasonal Activity ◽  
Tick Feeding ◽  
Rissa Tridactyla ◽  
Ixodes Uriae ◽  
Autumn And Winter ◽  
Temporal Overlap

SUMMARYWe investigated the timing of seasonal activity of the seabird tick Ixodes uriae by examining engorgement rates of off-host ticks and the prevalence of infested common guillemots (Uria aalge) and kittiwakes (Rissa tridactyla) on the Isle of May, Scotland. More than 99% of I. uriae fed during the period late April to early August which coincided with the seabird breeding season. No ticks fed in the autumn and winter, and none over-wintered in the engorged state. Peak tick feeding activity was during the hosts' incubation period in May and early June, when over 70% of birds were parasitized. Few ticks were active when guillemot chicks were being brooded, or during the early part of kittiwake chick-rearing. Adult female tick feeding peaked in the first week of June, while nymphal and larval activity peaked in the third week of May. Adult female ticks fed later than nymphs on guillemots and larvae on both guillemots and kittiwakes; however, there was considerable temporal overlap in the feeding periods of the 3 stages on both hosts. All larvae and nymphs fed in May and early June, but up to 18% of adult females remained unengorged at this time, and probably deferred feeding by 1 year. A small proportion of individuals which fed as larvae in May appeared to feed again as nymphs in July of the same season, thereby shortening their life-cycle by 1 year. The duration of the life-cycle of I. uriae on the Isle of May is typically 3 years but varies from 2 to 4 years. Ticks feeding on guillemots did so significantly earlier than those feeding on kittiwakes, possibly because guillemots start breeding earlier in the year. Breeding of both guillemots and kittiwakes was later in 1994 than in 1993. This delayed the activity of all tick stages on kittiwakes and adult female ticks on guillemots, but did not affect the timing of activity of nymphs or larvae feeding on guillemots.

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