Ectoparasites (sucking lice, fleas and ticks) of small mammals in southeastern Kenya

Data release: targeted systematic literature search for tick and tick-borne pathogen distributions in six countries in sub-Saharan Africa from 1901 to 2020

BACKGROUND

Surveillance data documenting tick and tick-borne disease (TBD) prevalence is needed to develop risk assessments and implement control strategies. Despite extensive research in Africa, there is no standardized, comprehensive review.

METHODS

Here we tackle this knowledge gap, by producing a comprehensive review of research articles on ticks and TBD between 1901 and 2020 in Chad, Djibouti, Ethiopia, Kenya, Tanzania, and Uganda. Over 8356 English language articles were recovered. Our search strategy included 19 related MeSH terms. Articles were reviewed, and 331 met inclusion criteria. Articles containing mappable data were compiled into a standardized data schema, georeferenced, and uploaded to VectorMap.

RESULTS

Tick and pathogen matrixes were created, providing information on vector distributions and tick-pathogen associations within the six selected African countries.

CONCLUSIONS

These results provide a digital, mappable database of current and historical tick and TBD distributions across six countries in Africa, which can inform specific risk modeling, determine surveillance gaps, and guide future surveillance priorities.

Ecological interactions, local people awareness and practices on rodent-borne diseases in Africa: A review

Several anthropogenic activities exposure humans to the risk of rodent-borne diseases. These activities are but not limited to logging, clearing land for crop cultivation, and consuming rodents. Rodents are a highly diverse mammalian group and harbor many zoonotic diseases. This review focuses on dominant rodent-flea species, rodent-borne zoonotic diseases and awareness and management practices against rodent-borne diseases in Africa. Relevant academic literature spanning from 1974 to 2021 was analysed. Dominant rodent species reported in Africa included:- Mastomys natalensis and Rattus rattus, while dominant flea species included Xenopsylla brasiliensis and Xenopsylla cheopis. Rodents were reported as hosts to a wide range of parasites which can be passed to humans. Rodents were also reported as hosts to some protozoans, trematodes, cestodes, nematodes, bacteria and viruses which are transmissible to humans. Some studies conducted in West Africa revealed good knowledge and practices on plague and Lassa fever diseases among respondents, whereas other studies reported poor practices on Lassa fever management. In part of Southern Africa, some studies reported poor knowledge and practices on plague disease. Further research on rodent-borne disease awareness and management strategies in African countries is desirable.

Ectoparasite load of small mammals in the Serengeti Ecosystem: effects of land use, season, host species, age, sex and breeding status

Ectoparasite load in small mammals can be influenced by both environmental conditions and host species characteristics. However, the nature of these influences is poorly understood in many ecosystems. We used zero-inflated negative binomial (ZINB) regression models with a log link function to assess variation in ectoparasite load among 19 small mammal host species across different land uses (protection in a park, pastoralism and agriculture), habitat types, seasons, age classes, sexes and breeding statuses. We collected 4258 ectoparasites from 612 individual belonging to 19 different species of small mammals. The average ectoparasite load per individual was higher in the pastoral and agricultural lands than in the National Park. Ectoparasite load varied among species and was the highest for the four common and generalist small mammal species (Aethomys sp., Arvicanthis niloticus, Mastomys natalensis, and Gerbilliscus vicinus), most notably in the disturbed pastoral and agricultural lands. It was also higher in the dry than the wet season and for adult males than adult females. These patterns partly reflect the greater mobility of small mammals in the drier conditions; in addition the large body size and home range of males increase the likelihood of encountering parasites. Human disturbance was associated with elevated ectoparasitic load among the small mammals and hence elevated risk of transmission of ectoparasites to humans. As a result, understanding the effect of habitat disturbance on ectoparasite load and its link to zoonotic disease risk should be an important conservation goal and public health priority. Moreover, effective pest control strategies should consider variation in ectoparasite load with land use, habitat type, season and species characteristics.

Rodents as potential hosts and reservoirs of parasites along the edge of a Central African forest: Bwindi impenetrable national park, South Western Uganda

BACKGROUND

Rodents which constitute 42% of the world's mammalian population are major reservoirs of pathogens that cause zoonoses. Currently we know little about rodents' potential zoonotic transfer from human settlements into protected areas and how any such threats might be reduced.

OBJECTIVE

To investigate the role of rodents as reservoirs of zoonotic pathogens along the boundary of Bwindi.

METHODS

A rodent inventory in three villages along the edge of Bwindi, was carried using live trapping techniques and the local rodents' ecto and endoparasite fauna investigated.

RESULTS

Two hundred eighty eight rodents captured belonged to 24 species, 17 genera and 4 families with Lophuromys aquilus being most abundant (30.2%). 240 ectoparasites which included mites, fleas and ticks were collected from 88 rodents out of 249. Proamys jacksoni rodents were most infested. Although the mites represented the largest proportion (84.6%), the highest species diversity was shown among the fleas (9 species). Some 36.9% of the rodents were infected with endoparasites of which L. aquilus haboured most. Endoparasitic genera identified included Nippostrongylus, Ascaris, Strongyloides, Trichuris, Hymenolepis, Taenia and Cryptosporidium.

CONCLUSION

Rodents have a zoonotic potentiality. There is need for developing effective integrated rodent management programs against rodent to reduce chances of parasite transmission within the protected areas.

Molecular detection of tick-borne pathogens harbored by ticks collected from livestock in the Xinjiang Uygur Autonomous Region, China

Ticks carry and transmit a wide range of pathogens (bacteria, viruses, and protozoa) that are of importance to humans and animals globally. However, information about the tick-borne pathogens harbored by ticks in the Xinjiang Uygur Autonomous Region (XUAR), northwestern China, is scarce. This study investigated the occurrence of tick species of domestic animals and tick-borne pathogens by using morphological molecular identification and sequence analysis in Turpan, Qitai, Altay, Hejing, Nileke, and Zhaosu counties (XUAR). A total of 5822 adult ticks (females and males) from 12 tick species were identified from 5 animal species (cattle, goats, sheep, camels, and horses) in 6 counties in the XUAR. Collected tick species included Dermacentor marginatus (24.7 %), Dermacentor nuttalli (20.8 %), Hyalomma anatolicum (13.7 %), Dermacentor niveus (13.1 %), Haemaphysalis punctata (10.7 %), Dermacentor silvarum (7.1 %), Dermacentor pavlovskyi (3.9 %), Hyalomma asiaticum (2.2 %), Rhipicephalus pumilio (1.9 %), Rhipicephalus sanguineus sensu lato (0.7 %), Rhipicephalus turanicus (0.6 %), and Hyalomma asiaticum kozlovi (0.6 %). Furthermore, 750 partially engorged adult ticks (females and males), including H. anatolicum (250), D. nuttalli (250), and D. marginatus (250), were individually separated according to species and sampling site, used for DNA extraction, and then screened for tick-borne pathogens. The most common pathogen was Rickettsia raoultii (36.80 %), followed by Brucella sp. (26.2 %), Anaplasma ovis (22.4 %), Babesia caballi (14.8 %), Theileria equi (8.7 %), and Theileria ovis (8.5 %). The sequencing of 6 genes showed a 96-100 % nucleotide identity between the sequences in this study and those deposited in GenBank. This study provides a scientific reference for the prevention and control of tick-borne diseases in the XUAR.

Fleas from domestic dogs and rodents in Rwanda carry Rickettsia asembonensis and Bartonella tribocorum

Fleas (Siphonaptera) are ubiquitous blood-sucking parasites that transmit a range of vector-borne pathogens. The present study examined rodents (n = 29) and domestic dogs (n = 7) living in the vicinity of the Volcanoes National Park, Rwanda, for fleas, identified flea species from these hosts, and detected Bartonella (Rhizobiales: Bartonellaceae) and Rickettsia (Rickettsiales: Rickettsiaceae) DNA. The most frequently encountered flea on rodents was Xenopsylla brasiliensis (Siphonaptera: Pulicidae). In addition, Ctenophthalmus (Ethioctenophthalmus) calceatus cabirus (Siphonaptera: Hystrichopsyllidae) and Ctenocephalides felis strongylus (Siphonaptera: Pulicidae) were determined using morphology and sequencing of the cytochrome c oxidase subunit I and cytochrome c oxidase subunit II genes (cox1 and cox2, respectively). Bartonella tribocorum DNA was detected in X. brasiliensis and Rickettsia asembonensis DNA (a Rickettsia felis-like organism) was detected in C. felis strongylus. The present work complements studies that clarify the distributions of flea-borne pathogens and potential role of fleas in disease transmission in sub-Saharan Africa. In the context of high-density housing in central sub-Saharan Africa, the detection of B. tribocorum and R. asembonensis highlights the need for surveillance in both rural and urban areas to identify likely reservoirs.

Landscapes with different biodiversity influence distribution of small mammals and their ectoparasitic chigger mites: A comparative study from southwest China

From a previous field investigation in Yunnan, southwest China between 2001 and 2015, we selected two types of landscapes to make a retrospectively comparative study on the distribution of small mammals and their ectoparasitic chigger mites. One landscape is "mountainous uncultivated land (MUL)" with higher biodiversity, which is located in a famous "World Nature Heritage Site", the Three-Parallel-Rivers Region in the northwest of Yunnan. The other is "cultivated flatland landscape (CFL)" with lower biodiversity, which is located in the south of Yunnan. The landscapes with different biodiversity apparently influenced the distribution of small mammals and their ectoparasitic chigger mites. Much more species of small mammals and mites were found in MUL than in CFL. A total of 3,177 small mammals captured from MUL were identified as 55 species, 30 genera and 10 families in five orders. From these small mammal hosts, 5,882 chigger mites were collected and identified as 127 species, 15 genera and 3 subfamilies in two families. A total of 1,112 small mammals captured from CFL were identified as 19 species, 12 genera and 5 families in three orders. From these hosts, 17,742 chiggers were collected and identified as 86 species, 12 genera and 3 subfamilies in two families. Both the species diversity (S = 55) and community diversity (H = 2.673) of small mammals in MUL were much higher than those in CFL (S = 19; H = 0.926). There were also higher values of β diversity in MUL than in CFL. Different main reservoir rodent hosts of zoonoses (including tsutsugamushi disease) were found in two types of landscapes. Rattus tanezumi (one main reservoir host) was most abundant in CFL, which accounted for 80.22% of all the small mammals. Another two main reservoir hosts, Eothenomys miletus and Apodemus chevrieri were the dominant species in MUL, but they were not as abundant as R. tanezumi in CFL. Different vector species of chigger mites also existed in MUL and CFL. Leptotrombidium deliense (a main and powerful vector of tsutsugamushi disease in China) and Ascoschoengastia indica (a potential vector of tsutsugamushi disease) were the dominant species of chigger mites in CFL (Cr = 25.81% for A. indica; Cr = 23.47% for L. deliense). Leptotrombidium scutellare (also a main vector of tsutsugamushi disease in China) was the dominant chigger species in MUL (Cr = 26.09%). Higher infestation of vector mites on small mammals was found in the simple landscape with lower biodiversity (CFL) than in the complex landscape with higher biodiversity (MUL). The overall prevalence (P), mean abundance (MA) and mean intensity (MI) of chigger mites on small mammals were much higher in CFL than in MUL. The main vector mite species on their main rodent hosts also showed a higher P, MA and MI in CFL than in MUL.

Comparison of Zoonotic Bacterial Agents in Fleas Collected from Small Mammals or Host-Seeking Fleas from a Ugandan Region Where Plague Is Endemic

Fleas play critical roles in transmitting some infections among animals and from animals to humans. Detection of pathogens in fleas is important to determine human risks for flea-borne diseases and can help guide diagnosis and treatment. Our findings of high prevalence rates of B. elizabethae and R. felis in fleas in the Arua and Zombo districts of Uganda implicate these agents as potential causative agents of undiagnosed febrile illnesses in this area.

Fleas (n = 407) were collected from small mammals trapped inside huts and surroundings of homesteads in five villages within the Arua and Zombo districts of Uganda. The most common flea species were Dinopsyllus lypusus (26%) and Xenopsylla cheopis (50%). Off-host fleas (n = 225) were collected inside huts by using Kilonzo flea traps. The majority of the off-host fleas were Ctenocephalides felis (80%). All fleas were examined for the presence of Bartonella spp., Rickettsia spp., and Yersinia spp. Bartonella DNA was detected in 91 fleas, with an overall prevalence of 14%. Bartonella prevalence was significantly higher in rodent or shrew fleas than in off-host fleas (22% versus 1%). The majority of Bartonella-positive fleas were of the species D. lypusus (61%), X. cheopis (20%), and Ctenophthalmus calceatus (14%). Sequencing analysis identified 12 Bartonella genetic variants, 9 of which belonged to the zoonotic pathogen B. elizabethae species complex. Rickettsia DNA was detected in 143 fleas, giving an overall prevalence of 23%, with a significantly higher prevalence in off-host fleas than in rodent or shrew fleas (56% versus 4%). The majority (88%) of Rickettsia-positive fleas were C. felis and were collected from Kilonzo traps, while a small portion (10%) were X. cheopis collected from rodents. Sequencing analysis identified six Rickettsia genogroups that belonged either to zoonotic R. felis or to the closely related “Candidatus Ricksettia asemboensis” and “Candidatus Ricksettia sengalensis.” Yersinia DNA was not detected in the fleas tested. These observations suggested that fleas in northwestern Uganda commonly carry the zoonotic agents B. elizabethae and R. felis and potentially play an important role in transmitting these infections to humans.

IMPORTANCE Fleas play critical roles in transmitting some infections among animals and from animals to humans. Detection of pathogens in fleas is important to determine human risks for flea-borne diseases and can help guide diagnosis and treatment. Our findings of high prevalence rates of B. elizabethae and R. felis in fleas in the Arua and Zombo districts of Uganda implicate these agents as potential causative agents of undiagnosed febrile illnesses in this area.

Host-Parasite Associations in Small Mammal Communities in Semiarid Savanna Ecosystems of East Africa

Despite the established importance of rodents as reservoirs of vector-borne zoonoses in East Africa, there is relatively limited information regarding the infestation parameters and host associations of ectoparasites that vector many such pathogens among small mammals in this region. Between 2009 and 2013, small mammals were live-trapped in the semiarid savanna of Kenya. A subset of these individual hosts, including 20 distinct host taxa, was examined for ectoparasites, which were identified to species. Species of fleas, ticks, mites, and sucking lice were recorded. Based on these data, we calculated host-specific infestation parameters, documented host preferences among ectoparasites, conducted a rarefaction analysis and extrapolation to determine if ectoparasites were adequately sampled, and assessed nestedness for fleas to understand how pathogens might spread in this system. We found that the flea community structure was significantly nested. Understanding the ectoparasite network structure may have significant human relevance, as at least seven of the ectoparasite species collected are known vectors of pathogens of medical importance in the region, including Yersinia pestis, Rickettsia spp., and Theileria parva, the causative agents of plague, spotted fevers and other rickettsial illnesses in humans, and theileriosis, respectively.

Species diversity of ectoparasitic chigger mites (Acari: Prostigmata) on small mammals in Yunnan Province, China

Chigger mites are a large group of arthropods and the larvae of mites are ectoparasites. Some species of ectoparasitic mites (larvae) can be the transmitting vectors of tsutsugamushi disease (scrub typhus). Yunnan Province is located in the southwest of China with complicated topographic landform and high biodiversity, where there are five zoogeographical subregions. Rodents and some other small mammals were trapped and examined for ectoparasitic chigger mites in 29 investigation sites in Yunnan during 2001-2013. From 13,760 individuals and 76 species of small mammal hosts, we collected 274 species of mites, which were identified as comprising 26 genera in two families. The species diversity of chigger mites (274 species) in the present study were not only much higher than that from other provinces of China but also largely exceeded that recorded from other regions and countries in the world. Of the five zoogeographical subregions, both the species diversity and Shannon-Weiner's diversity of mites were the highest in subregion II (southern subregion of Hengduan Mountains) with middle altitudes and middle latitude. Both the species diversity of mites and Shannon-Wiener diversity index showed a parabolic tendency from the low altitude (<500 m) to the high altitude (>3500 m) along the vertical gradients with the peak occurring in the middle-altitude regions (2000-2500 m). Of four dominant hosts, the species richness of mites was highest on Eothenomys miletus (S = 165) and Shannon-Wiener diversity index was highest on Rattus norvegicus (H = 3.13). Along latitude gradients, species richness of chigger mites increased first and then decreased, peaking at 25° to 26° N with 193 mite species. The geographical location, complex topography, and landscape with diverse small mammal hosts in Yunnan Province have contributed to the extremely high species diversity of mites in the province. The large sampling size of small mammal hosts in a wide geographical scope within a long time span also made it possible to have collected so many species of chigger mites.

Species Abundance Distribution of Ectoparasites on Norway Rats (Rattus norvegicus) from a Localized Area in Southwest China

BACKGROUND

The species of ectoparasites that live on a specific host in a geographical region form an ectoparasite community. Species abundance distributions describe the number of individuals observed for each different species that is encountered within a community. Based on properties of the species abundance distribution, the expected total number of species present in the community can be estimated.

METHODS

Preston's lognormal distribution model was used to fit the expected species abundance distribution curve. Using the expected species abundance distribution curve, we estimated the total number of expected parasite species present and the amount of species that were likely missed by our sampling in the field.

RESULTS

In total, 8040 ectoparasites (fleas, sucking lice, gamasid mites and chigger mites) were collected from 431 Norway rats (Rattus norvegicus) from a localized area in southwest China. These ectoparasites were identified to be 47 species from 26 genera in 10 families. The majority of ectoparasite species were chigger mites (family Trombiculidae) while the majority of individuals were sucking lice in the family Polyplacidae. The expected species abundance distribution curve demonstrated the classic pattern that the majority of ectoparasite species were rare and that there were a few common species. The total expected number of ectoparasite species on R. norvegicus was estimated to be 85 species, and 38 species were likely missed by our sampling in the field.

CONCLUSIONS

Norway rats harbor a large suite of ectoparasites. Future field investigations should sample large numbers of host individuals to assess ectoparasite populations.

Analysis of ectoparasites (chigger mites, gamasid mites, fleas and sucking lice) of the Yunnan red-backed vole (Eothenomys miletus) sampled throughout its range in southwest China

The Yunnan red-backed vole Eothenomys miletus (Rodentia: Cricetidae) is an endemic rodent species and reservoir host of zoonoses in southwest China. Based on a large host sample (2463 voles collected from 39 localities between 2001 and 2013), a general analysis of four categories of ectoparasite (fleas, sucking lice, chigger mites and gamasid mites) on E. miletus across its entire range of distribution was made. This analysis identified a total of 71 895 ectoparasites belonging to 320 species (30 species of flea, 9 of sucking louse, 106 of gamasid mite and 175 of chigger mite) with a high prevalence (87%), mean abundance (29.19) and mean intensity (33.69). Of the 18 vector species of zoonoses found on E. miletus, the flea Ctenophthalmus quadratus (Siphonaptera: Hystrichopsyllidae) and chigger mite Leptotrombidium scutellare (Trombidiformes: Trombiculidae) were the dominant species; these are the main vectors of zoonoses in China. All of the dominant parasite species showed an aggregated distribution pattern. Male voles harboured more species of parasite than females. Chigger mites represented the most abundant species group on voles and their prevalence was positively correlated with mean abundance (r = 0.73; P < 0.05). As a single rodent species, E. miletus has a high potential to harbour abundant ectoparasites with high species diversity and high rates of infestation. The sex of the vole affects ectoparasite infestation.

Faunal analysis of chigger mites (Acari: Prostigmata) on small mammals in Yunnan province, southwest China

This paper studied the species diversity and fauna distribution of chigger mites on small mammals in Yunnan province, southwest Yunnan. In total, 120,138 individuals of chigger mites were collected from 13,760 individual small mammals, and these mites were identified as comprising two families, 26 genera, and 274 species. Of the five zoogeographical subregions, the mite species diversity in subregions I and II was higher than that in subregions III, IV, and V. Four mite species (Leptotrombidium scutellare, Leptotrombidium sinicum, Leptotrombidium deliense, and Helenicula simena) were the most dominant species in the whole province. Several vector species of chigger mites co-existed in Yunnan, and L. deliense (a main vector of scrub typhus in China) was mainly distributed in subregions IV and V with lower latitude and average altitude whereas L. scutellare (also a main vector in China) was mainly distributed in subregions I, II, and III with higher latitude and average altitude. Some geographically widely distributed mite species were also the mites with wide host ranges and low host specificity. The dominant mite species and their clustering tendency in the dendrogram of hierarchical clustering analysis were highly in accordance with the zoogeographical divisions. The species diversity of chigger mites showed a parabolic tendency from the low altitude (<500 m) to the high altitude (>3,500 m) along the vertical gradients and reached the highest value in the middle altitude regions in 2,000-2,500 m. The highest species diversity of the mites and their small mammal hosts happened in the regions around the Hengduan Mountains, which is a hotspot of biodiversity in Asia continent. The host and its sample size, geographical scope, landscape, topography, and some other factors comprehensively influence the species diversity and faunal distribution of chigger mites. A systematic field investigation with a wide geographical scope and large host sample is strongly recommended in the fauna study of chigger mites and other ectoparasites.

Environment-related and host-related factors affecting the occurrence of lice on rodents in Central Europe

We studied the effects of environment- (habitat, season) and host-related (sex, body mass) factors on the occurrence of four species of lice (Insecta:Phthiraptera:Anoplura) on six rodent species (Rodentia:Muridae). We asked how these factors influence the occurrence of lice on an individual host and whether different rodent–louse associations demonstrate consistent trends in these effects. We found significant effects of at least one environment-related and at least one host-related factor on the louse occurrence in five of six host–louse associations. The effect of habitat was significant in two associations with the occurrence of lice being more frequent in lowland than in mountain habitats. The effect of season was significant in five associations with a higher occurrence of infestation during the warm season in four associations and the cold season in one association. Host sex affected significantly the infestation by lice in three associations with a higher frequency of infestation in males. Host body mass affected the occurrence of lice in all five associations, being negative in wood mice and positive in voles. In conclusion, lice were influenced not only by the host- but also by environment-related factors. The effects of the latter could be mediated via life history parameters of a host.

The Namaqua rock mouse (Micaelamys namaquensis) as a potential reservoir and host of arthropod vectors of diseases of medical and veterinary importance in South Africa

Background

The role of endemic murid rodents as hosts of arthropod vectors of diseases of medical and veterinary significance is well established in the northern hemisphere. In contrast, endemic murids are comparatively understudied as vector hosts in Africa, particularly in South Africa. Considering the great rodent diversity in South Africa, many of which may occur as human commensals, this is unwarranted.

Methods

In the current study we assessed the ectoparasite community of a widespread southern African endemic, the Namaqua rock mouse (Micaelamys namaquensis), that is known to carry Bartonella spp. and may attain pest status. We aimed to identify possible vectors of medical and/or veterinary importance which this species may harbour and explore the contributions of habitat type, season, host sex and body size on ectoparasite prevalence and abundance.

Results

Small mammal abundance was substantially lower in grasslands compared to rocky outcrops. Although the small mammal community comprised of different species in the two habitats, M. namaquensis was the most abundant species in both habitat types. From these 23 ectoparasite species from four taxa (fleas, ticks, mites and lice) were collected. However, only one flea (Xenopsylla brasiliensis) and one tick species (Haemaphysalis elliptica) have a high zoonotic potential and have been implicated as vectors for Yersinia pestis and Bartonella spp. and Rickettsia conorii, respectively. The disease status of the most commonly collected tick (Rhipicephalus distinctus) is currently unknown. Only flea burdens differed markedly between habitat types and increased with body size. With the exception of lice, all parasite taxa exhibited seasonal peaks in abundance during spring and summer.

Conclusion

M. namaquensis is the dominant small mammal species irrespective of habitat type. Despite the great ectoparasite diversity harboured by M. namaquensis, only a small number of these are known as vectors of diseases of medical and/or veterinary importance but occur at high prevalence and/or abundance. This raises concern regarding the potential of this host as an endemic reservoir for zoonotic diseases. Consequently, additional sampling throughout its distributional range and research addressing the role of M. namaquensis as a reservoir for zoonotic diseases in southern Africa is urgently needed.

Differentiation of flea communities infesting small mammals across selected habitats of the Baltic coast, central lowlands, and southern mountains of Poland

Only a few studies comparing flea composition on the coast and in the mountains have been conducted. We investigated differences in flea communities infesting small mammals in selected habitats in northern, central, and southern Poland. We predicted (1) a greater number of flea species in the southeastern Poland and a lower number in the north, (2) a greater number of flea species in fertile and wet habitats than in poor and arid habitats, and (3) a low similarity of flea species between flea communities in western and eastern Poland. We found a negative effect of increasing latitude on flea species richness. We suppose that the mountains providing a variety of environments and the limits of the geographic ranges of several flea subspecies in southeastern Poland result in a higher number of flea species. There was a positive effect of increasing wetness of habitat on flea species richness. We found a high diversity in flea species composition between western and eastern Poland (beta diversity = 11) and between central and eastern Poland (beta diversity = 12). Re-colonization of Poland by small mammals and their ectoparasites from different (western and eastern) refugees can affect on this high diversity of flea species.

Abundances and host relationships of chigger mites in Yunnan Province, China

This paper reports on ectoparasitic chigger mites found on small mammals in Yunnan Province, southwest China. Data were accumulated from 19 investigation sites (counties) between 2001 and 2009. A total of 10 222 small mammal hosts were captured and identified; these represented 62 species, 34 genera and 11 families in five orders. From the body surfaces of these 10 222 hosts, a total of 92 990 chigger mites were collected and identified microscopically. These represented 224 species, 22 genera and three subfamilies in the family Trombiculidae (Trombidiformes). Small mammals were commonly found to be infested by chigger mites and most host species harboured several species of mite. The species diversity of chigger mites in Yunnan was much higher than diversities reported previously in other provinces of China and in other countries. A single species of rodent, Eothenomys miletus (Rodentia: Cricetidae), carried 111 species of chigger mite, thus demonstrating the highest species diversity and heaviest mite infestation of all recorded hosts. This diversity is exceptional compared with that of other ectoparasites. Of the total 224 mite species, 21 species accounted for 82.2% of all mites counted. Two species acting as major vectors for scrub typhus (tsutsugamushi disease), Leptotrombidium scutellare and Leptotrombidium deliense, were identified as the dominant mite species in this sample. In addition to these two major vectors, 12 potential or suspected vector species were found. Most species of chigger mite had a wide range of hosts and low host specificity. For example, L. scutellare parasitized 30 species of host. The low host specificity of chigger mites may increase their probability of encountering humans, as well as their transmission of scrub typhus among different hosts. Hierarchical clustering analysis showed that similarities between different chigger mite communities on the 18 main species of small mammal host did not accord with the taxonomic affinity of the hosts. This suggests that the distribution of chigger mites may be strongly influenced by the environment in which hosts live.

Analysis of gamasid mites (Acari: Mesostigmata) associated with the Asian house rat, Rattus tanezumi (Rodentia: Muridae) in Yunnan Province, southwest China

During a survey lasting from 1990 to 2008, we captured 4,113 Asian house rats, Rattus tanezumi Temminck 1844 (Rodentia: Muridae) from 28 counties of Yunnan Province in southwestern China. From these rats, a total of 19,304 gamasid mites (Acari: Mesostigmata) were collected and identified as comprising 50 different species. The species diversity of gamasid mites from this single rat species is higher than that reported previously from multiple hosts within a given geographical region. Of the 50 mite species, 31 species belonged to ectoparasites and 19 species belonged to free-living mites. The species diversity of the mites from rats trapped outdoors was much higher than from rats trapped indoors. The parameter K from the negative binomial distribution was used to measure the spatial distribution patterns of the dominant mite species and revealed that all the mites had an aggregated distribution among the rat hosts. Most mite species showed a predominantly female-biased population structure with many more females than males.

Preliminary investigation on rodent-ectoparasite associations in the highlands of Tigray, Northern Ethiopia: implications for potential zoonoses

We studied associations between rodents and their arthropod ectoparasites in crop fields and household compounds in the highlands of Tigray, Northern Ethiopia. Ectoparasite infestation indices, such as percent infestation, mean abundance, prevalence and host preferences, were calculated for each taxon. In total, 172 rodents from crop fields and 97 from household compounds were trapped. Rodent species and numbers trapped from the crop fields and household compounds were Mastomys awashensis (Lavrenchenko, Likhnova & Baskevich, 1998) (88 and 44), Arvicanthis dembeensis (Ruppel, 1842) (63 and 37) and Acomys sp. (21 and 16), respectively. A total of 558 insects and acarids (belonging to 11 taxa) were recovered from the rodents trapped in the crop fields, and 296 insects and acarid (belonging to 6 taxa) from the rodents trapped in the household compounds. Approximately 66% of the rodents trapped from the crop fields and 47% of those trapped from the household compounds were infested with ectoparasites. Laelaps sp. (64.9%) and Xenopsylla sp. (20.6%) comprised the highest proportion of the ectoparasites recovered in the crop fields, and the same ectoparasites, but in reverse order, comprised the highest proportions in the household compounds (Xenopsylla [50.3%] and Laelaps sp. [29%]). Our study revealed that crop fields and household compounds in the highlands share similar rodents and several ectoparasites. Furthermore, at least 1 of the rodent species and some of the ectoparasites identified in this study were reported to have posed medical and veterinary threats in other parts of Ethiopia and neighboring countries.

Host selection and niche differentiation in sucking lice (Insecta: Anoplura) among small mammals in southwestern China

Understanding factors that shape host selection has been a classic issue in ecology, evolutionary biology, and epidemiological investigation. During the survey from 2000 to 2009, a total of 11,216 individuals of small mammals were captured from Yunnan Province in southwestern China. The captured small mammalian hosts belong to five orders, ten families, 35 genera, and 65 species and from their body surface, 38,885 individuals of ectoparasitic sucking lice were collected, which represent five families, seven genera, and 31 species. Based on niche overlap of dominant sucking lice on their primary hosts, we used hierarchical cluster analysis to sort different sucking louse species' resource utilizations of similar kind into respective categories. Given λ<5, there are only two groups clustered, however, sucking louse species' resource utilization was sorted into eight respective categories at λ=15. The results revealed that most species of sucking lice usually had high host specificity and a certain species of sucking louse usually restricted to one or few small mammalian species as their dominant hosts. Correspondence analysis was used to visualize associations between parasitic sucking lice and their small mammalian hosts, which suggested three different patterns of host resource utilization: species specialists, genera generalists, and multiple selections. For example, Sathrax durus (Johnson) only parasitized on species of Tupaia belangeri (Wagner), Hoplopleura edentula (Fahredholz) predominatly on genus of Eothenomys, and Polyplax reclinata (Nitzsch) on Family of Soricidae. Our results demonstrate that sucking lice have high host specificity and this might be due to coevolution between sucking lice and their hosts.