The life cycle of spirochetes of the genus Borrelia includes complex networks of vertebrates and ticks. The tripartite association of Borrelia-vertebrate-tick has proved ecologically successful for these bacteria, which have become some of the most prominent tick-borne pathogens in the northern hemisphere. To keep evolutionary pace with its double-host life history, Borrelia must adapt to the evolutionary pressures exerted by both sets of hosts. In this review, we attempt to reconcile functional, phylogenetic, and ecological perspectives to propose a coherent scenario of Borrelia evolution. Available empirical information supports that the association of Borrelia with ticks is very old. The major split between the tick families Argasidae-Ixodidae (dated some 230-290 Mya) resulted in most relapsing fever (Rf) species being restricted to Argasidae and few associated with Ixodidae. A further key event produced the diversification of the Lyme borreliosis (Lb) species: the radiation of ticks of the genus Ixodes from the primitive stock of Ixodidae (around 217 Mya). The ecological interactions of Borrelia demonstrate that Argasidae-transmitted Rf species remain restricted to small niches of one tick species and few vertebrates. The evolutionary pressures on this group are consequently low, and speciation processes seem to be driven by geographical isolation. In contrast to Rf, Lb species circulate in nested networks of dozens of tick species and hundreds of vertebrate species. This greater variety confers a remarkably variable pool of evolutionary pressures, resulting in large speciation of the Lb group, where different species adapt to circulate through different groups of vertebrates. Available data, based on ospA and multilocus sequence typing (including eight concatenated in-house genes) phylogenetic trees, suggest that ticks could constitute a secondary bottleneck that contributes to Lb specialization. Both sets of adaptive pressures contribute to the resilience of highly adaptable meta-populations of bacteria.
- MeSH
- Adaptation, Biological MeSH
- Biological Evolution * MeSH
- Borrelia classification physiology MeSH
- Disease Vectors * MeSH
- Host-Pathogen Interactions MeSH
- Ticks microbiology MeSH
- Humans MeSH
- Lyme Disease microbiology transmission MeSH
- Selection, Genetic MeSH
- Disease Reservoirs * microbiology MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
Lymnaeid snails of the genus Radix serve as intermediate hosts of some schistosomes and fasciolids. In Europe, delineation of species within the genus Radix is unresolved and, therefore, spectrum of snail hosts susceptible to trematode infections is under discussion. We used and compared three criteria for species delineation using snails collected at 43 localities. (a) Sequence analysis of ITS-2 rDNA disclosed that the collected snails belong to four species - R. auricularia (Linnaeus, 1758), R. peregra (Müller, 1774), R. lagotis (Schrank, 1803) and R. labiata (Rossmaessler, 1835) (criteria and names are based on the work of Bargues et al. 2001). Occurrence of R. peregra in the Czech Republic was confirmed by molecular data for the first time. (b) Characterization of reproductive system disclosed differences in location, size and shape of bursa copulatrix and its ductus. Unfortunately, some R. labiata specimens shared morphological features of reproductive organs with R. lagotis. (c) Statistical analysis of shell morphology proved that significant differences exist among particular species. One prediction model showed that correct classification of species may be achieved in 82-84% of cases. However, identification of individual snails in the field (without knowledge of respective snail population and use of statistical tools) still remains a complicated issue due to overlaps of shell characteristics. Concerning the role in trematode transmission, R. lagotis, R. labiata and R. peregra are susceptible to Trichobilharzia regenti. Also, successful experimental infections of R. lagotis and R. labiata by Fascioloides magna were accomplished.
- MeSH
- Species Specificity MeSH
- Snails parasitology MeSH
- Host-Parasite Interactions MeSH
- Trematoda physiology MeSH
- Disease Reservoirs * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Czech Republic MeSH
Zoonotic cutaneous leishmaniasis (ZCL) is an expanding disease and a public health issue in Iran. In the present study, rate of natural infection of rodent populations with Leishmania was investigated in six endemic foci including 28 villages in Golestan, Esfahan, Yazd, Fars, Khuzestan and Ilam provinces. A total of 593 rodents were captured and identified as Rhombomys opimus (n = 325), Meriones libycus (n = 171), Meriones persicus (n = 27), Tatera indica (n = 37), Nesokia indica (n = 12), Rattus rattus (n = 13) and Mus musculus (n = 8). Microscopic examinations of Giemsa-stained smears showed that 108 out of 593 (18.2%) rodents were infected with Leishmania spp., whereas infection of 186 out of 593 (31.4%) rodents with Leishmania was then confirmed by ITS1-PCR. The highest rate of infection was found in R. opimus (prevalence of 35%) and M. libycus (31%). Based on Restriction Fragment Length Polymorphism (RFLP), 145 (78%) of 186 samples detected as Leishmania DNA were identified as L. major, 8 (4%) samples as L. turanica and 33 (18%) as mixed infection (L. major and L. turanica). Samples from infected rodents were inoculated subcutaneously at tail base of BALB/c mice. In 35 of them, nodules and ulcers containing amastigotes appeared at the inoculation site. The samples prepared from infected rodents were cultured in NNN medium and only two samples werepositive. Rhombomys opimus, M. libycus, M. persicus, T. indica and N. indica were confirmed as reservoir hosts of ZCL in the studied regions. Leishmania major infection was usually accompanied L. turanica in naturally infected gerbils (R. opimus and M. libycus) in Golestan, Esfahan and Fars provinces.
- MeSH
- Animals, Wild MeSH
- Species Specificity MeSH
- Endemic Diseases MeSH
- Rodentia microbiology MeSH
- Leishmania classification genetics MeSH
- Leishmaniasis, Cutaneous veterinary MeSH
- Humans MeSH
- Mice, Inbred BALB C MeSH
- Mice MeSH
- Polymorphism, Restriction Fragment Length MeSH
- DNA, Protozoan classification genetics MeSH
- Disease Reservoirs veterinary MeSH
- Zoonoses MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Iran MeSH
Reaction of vertebrate serum complement with different Borrelia burgdorferi sensu lato species is used as a basis in determining reservoir hosts among domesticated and wild animals. Borrelia burgdorferi sensu stricto, Borrelia garinii, and Borrelia afzelii were tested for their sensitivity to sera of exotic vertebrate species housed in five zoos located in the Czech Republic. We confirmed that different Borrelia species have different sensitivity to host serum. We found that tolerance to Borrelia infection possessed by hosts might differ among individuals of the same genera or species and is not affected by host age or sex. Of all zoo animals included in our study, carnivores demonstrated the highest apparent reservoir competency for Lyme borreliosis spirochetes. We showed that selected exotic ungulate species are tolerant to Borrelia infection. For the first time we showed the high tolerance of Siamese crocodile to Borrelia as compared to the other studied reptile species. While exotic vertebrates present a limited risk to the European human population as reservoirs for the causative agents of Lyme borreliosis, cases of incidental spillover infection could lead to successful replication of the pathogens in a new host, changing the status of selected exotic species and their role in pathogen emergence or maintenance. The question if being tolerant to pathogen means to be a competent reservoir host still needs an answer, simply because the majority of exotic animals might never be exposed to spirochetes in their natural environment.
- MeSH
- Borrelia burgdorferi physiology MeSH
- Complement System Proteins pharmacology MeSH
- Lyme Disease immunology microbiology veterinary MeSH
- Vertebrates immunology MeSH
- Disease Reservoirs MeSH
- Animals, Zoo MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
BACKGROUND: Fascioloides magna is a pathogenic fluke introduced to Europe ca 140 years ago. As it is spreading over the continent, new intermediate and definitive hosts might be involved in transmission of the parasite. In Europe, several studies reported potential new intermediate snail hosts (Radix spp.) for F. magna, and also several cases of fascioloidosis of wild and domestic animals were published. However, the data based on molecular and histological analyses confirming these findings remained unreported. This study aims to refer to unique findings of F. magna in European snails and domestic animals (the first observation in the Czech Republic in the last 30 years) and demonstrate the use of molecular techniques in determination of F. magna. RESULTS: Two snails of R. labiata naturally infected with F. magna were found; mature cercariae and daughter rediae were observed. Maturity of cercariae was checked by histological methods, however, their ability to encyst was not confirmed. Co-infection of F. magna and Fasciola hepatica in the liver of two highland cattle bulls was proved. Adult fasciolid flukes producing eggs were found in the liver pseudocysts (F. magna) and the bile ducts (F. hepatica). Identification of intermediate hosts, intramolluscan stages, adult flukes and eggs was performed by sequencing the ITS2 region. Connection of F. magna pseudocysts with the gut (via the bile ducts) was not confirmed by means of histological and coprological examinations. CONCLUSIONS: For the first time, Radix labiata was confirmed as the snail host for F. magna under natural conditions and, together with the finding of F. magna infection in cattle, we can expect further transmission of F. magna from wildlife to livestock in localities shared by these hosts.
- MeSH
- Fasciolidae classification MeSH
- Snails parasitology MeSH
- Trematode Infections epidemiology parasitology veterinary MeSH
- Cattle Diseases epidemiology parasitology MeSH
- Cattle MeSH
- Disease Reservoirs MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Cattle MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Czech Republic MeSH
Vector-borne pathogens establish systemic infections in host tissues to maximize transmission to arthropod vectors. Co-feeding transmission occurs when the pathogen is transferred between infected and naive vectors that feed in close spatiotemporal proximity on a host that has not yet developed a systemic infection. Borrelia afzelii is a tick-borne spirochete bacterium that causes Lyme borreliosis (LB) and is capable of co-feeding transmission. Whether ticks that acquire LB pathogens via co-feeding are actually infectious to vertebrate hosts has never been tested. We created nymphs that had been experimentally infected as larvae with B. afzelii via co-feeding or systemic transmission, and compared their performance over one complete LB life cycle. Co-feeding nymphs had a spirochete load that was 26 times lower than systemic nymphs but both nymphs were highly infectious to mice (i.e., probability of nymph-to-host transmission of B. afzelii was ~100%). The mode of transmission had no effect on the other infection phenotypes of the LB life cycle. Ticks that acquire B. afzelii via co-feeding transmission are highly infectious to rodents, and the resulting rodent infection is highly infectious to larval ticks. This is the first study to show that B. afzelii can use co-feeding transmission to complete its life cycle.
- MeSH
- Arachnid Vectors microbiology physiology MeSH
- Ticks microbiology physiology MeSH
- Animal Feed microbiology MeSH
- Lyme Disease microbiology transmission MeSH
- Mice MeSH
- Nymph microbiology physiology MeSH
- Life Cycle Stages MeSH
- Disease Reservoirs microbiology MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Comparative Study MeSH
Anaplasma phagocytophilum is a worldwide distributed bacterium with a significant medical and veterinary importance. It grows within the phagosome of infected neutrophils and is responsible for human granulocytic anaplasmosis (HGA), tick-borne fever (TBF) of small ruminants and cattle, canine and equine granulocytic anaplasmosis, but infects also a great variety of wildlife species. Wild ungulates and rodents are considered reservoirs of infection in natural foci. The objective of this study was to determine the spectrum of animal species involved in the circulation of A. phagocytophilum in Slovakia and to analyze the variability of obtained nucleotide sequences, in order to determine whether genotypes from Slovakia cluster according to host-species or geographical location. Several animal species and vector ticks were screened for the presence of members of the family Anaplasmataceae using PCR based methods. Additional data on the molecular evidence of Anaplasma ovis and Candidatus Neoehrlichia mikurensis are presented. These pathogens were detected in tested sheep flocks and rodents with the mean infection rates of 8.16% and 10.75%, respectively. A. phagocytophilum was genotyped by 16S rRNA and groEL gene sequencing. Bacterial DNA was confirmed in questing ixodid ticks, in domesticated canine, wild rodents and several species of wild ungulates. In European isolates, 16S rRNA gene does not seem to be an appropriate locus for the analyses of heterogeneity as it is too conservative. Similarly, 16S rRNA isolates from our study did not reveal any polymorphisms. All isolates were identical in overlapped region and showed identity with sequences from ticks, horses or ruminants previously isolated elsewhere in the world. On the other hand, the groESL heat shock operon is widely used for determination of diversity and the analyses have already revealed considerable degree of heterogeneity. Tested ungulates were infected with A. phagocytophilum to a considerable extent. High proportions of red and roe deer tested positive and the rates of infection reached over 60.0%. GroEL sequences from canine, wild ungulates and ticks from Slovakia clustered within a clade together with isolates from horses, humans, wild ungulates and ticks from Slovakia or elsewhere in the world. Sequences from rodents clustered apart from those obtained from wild ungulates, ticks and humans. These results suggest that European rodents do not harbour A. phagocytophilum strains with strong zoonotic potential such as those from United States.
- MeSH
- Anaplasma classification genetics isolation & purification MeSH
- Anaplasmosis MeSH
- Arachnid Vectors microbiology MeSH
- Rodentia MeSH
- Ixodes microbiology MeSH
- Dogs MeSH
- Deer MeSH
- Disease Reservoirs microbiology MeSH
- Animals MeSH
- Check Tag
- Dogs MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Slovakia MeSH
Endemic regions for Puumala virus (PUUV) are located in the most affected federal state Baden-Wuerttemberg, South-West Germany, where high numbers of notified human hantavirus disease cases have been occurring for a long time. The distribution of human cases in Baden-Wuerttemberg is, however, heterogeneous, with a high number of cases recorded during 2012 in four districts (H districts) but a low number or even no cases recorded in four other districts (L districts). Bank vole monitoring during 2012, following a beech (Fagus sylvatica) mast year, resulted in the trapping of 499 bank voles, the host of PUUV. Analyses indicated PUUV prevalences of 7-50% (serological) and 1.8-27.5% (molecular) in seven of eight districts, but an absence of PUUV in one L district. The PUUV prevalence differed significantly between bank voles in H and L districts. In the following year 2013, 161 bank voles were trapped, with reduced bank vole abundance in almost all investigated districts except one. In 2013, no PUUV infections were detected in voles from seven of eight districts. In conclusion, the linear modelling approach indicated that the heterogeneous distribution of human PUUV cases in South-West Germany was caused by different factors including the abundance of PUUV RNA-positive bank voles, as well as by the interaction of beech mast and the proportional coverage of beech and oak (Quercus spec.) forest per district. These results can aid developing local public health risk management measures and early warning models.
- MeSH
- Arvicolinae blood virology MeSH
- Ecosystem MeSH
- Hemorrhagic Fever with Renal Syndrome epidemiology MeSH
- Humans MeSH
- Murinae MeSH
- Antibodies, Viral blood MeSH
- Risk Factors MeSH
- RNA, Viral isolation & purification MeSH
- Seasons MeSH
- Puumala virus * MeSH
- Disease Reservoirs virology MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Germany epidemiology MeSH
A key aim in wildlife disease ecology is to understand how host and parasite characteristics influence parasite transmission and persistence. Variation in host population density can have strong impacts on transmission and outbreaks, and theory predicts particular transmission-density patterns depending on how parasites are transmitted between individuals. Here, we present the results of a study on the dynamics of Morogoro arenavirus in a population of multimammate mice (Mastomys natalensis). This widespread African rodent, which is also the reservoir host of Lassa arenavirus in West Africa, is known for its strong seasonal density fluctuations driven by food availability. We investigated to what degree virus transmission changes with host population density and how the virus might be able to persist during periods of low host density. A seven-year capture-mark-recapture study was conducted in Tanzania where rodents were trapped monthly and screened for the presence of antibodies against Morogoro virus. Observed seasonal seroprevalence patterns were compared with those generated by mathematical transmission models to test different hypotheses regarding the degree of density dependence and the role of chronically infected individuals. We observed that Morogoro virus seroprevalence correlates positively with host density with a lag of 1-4 months. Model results suggest that the observed seasonal seroprevalence dynamics can be best explained by a combination of vertical and horizontal transmission and that a small number of animals need to be infected chronically to ensure viral persistence. Transmission dynamics and viral persistence were best explained by the existence of both acutely and chronically infected individuals and by seasonally changing transmission rates. Due to the presence of chronically infected rodents, rodent control is unlikely to be a feasible approach for eliminating arenaviruses such as Lassa virus from Mastomys populations.
- MeSH
- Arenavirus immunology MeSH
- Population Density MeSH
- Arenaviridae Infections epidemiology MeSH
- Mice MeSH
- Rodent Diseases epidemiology MeSH
- Antibodies, Viral MeSH
- Seroepidemiologic Studies MeSH
- Disease Reservoirs veterinary MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Tanzania MeSH
