Host finding of the pigeon tick Argas reflexus

The medically and veterinary important feral pigeon tick Argas reflexus (Ixodida: Argasidae) Fabricius usually feeds on pigeons, but if its natural hosts are not available, it also enters dwellings to bite humans that can possibly react with severe allergic reactions. Argas reflexus is ecologically extremely successful as a result of some outstanding morphological, physiological, and ethological features. Yet, it is still unknown how the pigeon tick finds its hosts. Here, different host stimuli such as living nestlings as well as begging calls, body heat, smell, host breath and tick faeces, were tested under controlled laboratory conditions. Of all stimuli tested, only heat played a role in host‐finding. The heat stimulus was then tested under natural conditions within a pigeon loft. The results showed that A. reflexus is able to find a host over short distances of only a few centimetres. Furthermore, it finds its host by random movements and recognizes a host only right before direct contact is made. The findings are useful for the control of A. reflexus in infested apartments, both to diagnose an infestation and to perform a success monitoring after disinfestation.     

Protecting buildings against feral pigeons

Feral pigeons (Columba livia, Gmelin 1789) cause different problems for building owners when using structures for daytime perching, sleeping, and breeding. Problems include fouling of building facades and pavements, transmission of allergens and pathogenic microorganisms, and infestations with ectoparasites emanating from breeding sites. Owners are primarily interested in keeping away unwanted pigeons from their property. Pest control companies offer different deterrent systems, of widely varying efficacy, for proofing buildings against feral pigeons. A better solution is avoiding attractive structures during building design or subsequent alterations of existing structures used by feral pigeons. With our study, we elaborate the relevant structural data to help to maintain a building free of pigeons. We performed experiments with free ranging feral pigeons in a feral pigeon loft in the City of Basel, Switzerland. The maximum outlet width a pigeon is not able to pass through is 4 cm; the respective outlet height is 5 cm and a pigeon-safe square opening is not larger than 6 × 6 cm. The maximum ledge width a pigeon is not able to sit on is 4 cm. The pigeon-safe angle of inclination for smooth construction materials (tinplate, glass, plastics) is 25°, for medium rough materials (wood, plane concrete) 35°, and for rough materials (sandstone, rough concrete) at least 50°. Additionally, we studied the behavioral strategies used by feral pigeons to surmount our experimental constructional restrictions, ledge width, and ledge inclinations. Our data provide the essential data to prevent feral pigeons from using building structures.     

Ixodid ticks associated with feral swine in Texas

Ixodid ticks were collected from feral swine in eight Texas ecoregions from 2008–2011. Sixty‐two percent of 806 feral swine were infested with one or more of the following species: Amblyomma americanum, A. cajennense, A. maculatum, Dermacentor albipictus, D. halli, D. variabilis, and Ixodes scapularis. Juvenile and adult feral swine of both sexes were found to serve as host to ixodid ticks. Longitudinal surveys of feral swine at four geographic locations show persistent year‐round tick infestations of all gender‐age classes for tick species common to their respective geographic locations and ecoregions. Amblyomma americanum, A. cajennense, A. maculatum and D. variabilis were collected from 66% of feral swine harvested through an abatement program in seven ecoregions from March to October in 2009. These results indicate westward geographic expansion of D. variabilis. Summary results show feral swine are competent hosts for ixodid species responsible for the transmission of pathogens and diminished well‐being in livestock, wildlife, and humans.     

Trap perches to assess the activity of pyrethrins against the poultry red miteDermanyssus gallinae in cage birds

Trap perches were utilised to quantify mite recoveries during efficacy tests of pyrethrin formulations against experimental infestations ofDermanyssus gallinae (De Geer, 1778) in budgerigars and pigeons, and to monitor mite recoveries from untreated canaries. Pyrethrins applied topically before infestation significantly reduced the mean numbers of poultry red mites found in both budgerigar and pigeon trap perches, over those in untreated controls (P=<0.01). In untreated control budgerigars and pigeons, and in untreated canaries, the percentage recoveries after 48 h were 12.6±1.6, 4.1±1.9, and 32.6±1.6%, respectively (geometric mean±sd), and the blood engorgements rates were 71.5±1.7, 11.9±5.1, and 90.1±1.0% respectively. The recovery in trap perches of mites from canaries declined exponentially; 85% of the cumulative total recovered was collected 24 h after infestation, but small numbers were recovered daily up to 96 h (limit of observation). The use of the trap perches is discussed as a way of assessing the efficacy of acaricides, and as a laboratory tool in studies on mite aggregation behaviour or immune responses to mite infestation.     

Antibiotic resistance in faecal bacteria (Escherichia coli,Enterococcus spp.) in feral pigeons

Aims: To determine the presence of antibiotic‐resistant faecal Escherichia coli and Enterococcus spp. in feral pigeons (Columba livia forma domestica) in the Czech Republic. Methods and Results: Cloacal swabs of feral pigeons collected in the city of Brno in 2006 were cultivated for antibiotic‐resistant E. coli. Resistance genes, class 1 and 2 integrons, and gene cassettes were detected in resistant isolates by polymerase chain reaction (PCR). The samples were also cultivated for enterococci. Species status of enterococci isolates was determined using repetitive extragenic palindromic‐PCR. Resistance genes were detected in resistant enterococci by PCR. E. coli isolates were found in 203 of 247 pigeon samples. Antibiotic resistance was recorded in three (1·5%, n_E. coli = 203) isolates. Using agar containing ciprofloxacin, 12 (5%, n_samples = 247) E. coli strains resistant to ciprofloxacin were isolated. No ESBL‐producing E. coli isolates were detected. A total of 143 enterococci were isolated: Ent. faecalis (36 isolates), Ent. faecium (27), Ent. durans (19), Ent. hirae (17), Ent. mundtii (17), Ent. gallinarum (12), Ent. casseliflavus (12) and Ent. columbae (3). Resistance to one to four antibiotics was detected in 45 (31%) isolates. Resistances were determined by tetK, tetL, tetM, tetO, aac(6′)aph(2′′), ant(4′)‐Ia, aph(3′)‐IIIa, ermB, pbp5, vanA and vanC1 genes. Conclusions: Antibiotic‐resistant E. coli and Enterococcus spp. occurred in feral pigeons in various prevalences. Significance and Impact of the Study: Feral pigeon should be considered a risk species for spreading in the environment antimicrobial resistant E. coli and enterococci.     

Prevalence of yeast-like fungi and evaluation of several virulence factors from feral pigeons in Seoul, Korea

Aims: Studies of pigeon‐borne yeasts have tended to focus on species, such as Cryptococcus neoformans and Candida albicans, with scant attention to feral pigeons in Korea. We studied the prevalence of yeasts from faecal samples of feral pigeons obtained in various public places in Seoul, Korea, and assessed their potential capacity as human pathogens. Methods and Results: Three hundred and six pigeon faeces samples were collected at city squares and parks in 21 localities in Seoul and Seoul Grand Park and analysed for yeast with conventional methods. Of the 306 samples, 126 (41·2%) were positive for yeast. Seventeen species of yeast were identified. The most frequent species were Candida glabrata (34·1%), Candida famata (12·7%), Cryptococcus albidus (14·3%) and Cryptococcus laurentii (7·9%). The yeast isolates were tested for virulence. Of the 116 isolates (ten isolates missing), 70·7% (n = 82) grew at 37°C. All the Cryptococcus spp. isolates possessed a capsule, 16·4% (n = 19) produced melanin, and 33·6% (n = 39) produced proteinase. Two Ca. glabrata, a Ca. famata and Ca. albicans as well as three C. neoformans, a C. laurentii and Ca. albicans isolates had three virulence factors. Accordingly, 29·3% (n = 34) isolates possessed more than two virulence factors except capsule formation. Conclusions: These results of this study indicate that feral pigeons harbour a variety of yeasts and are a reservoir of human pathogenic fungi. Significance and Impact of the Study: This study is the first time about the microflora (fungi) presents in faecal samples collected from a variety of public areas throughout Seoul, Korea.     

Investigation of a gamasid mite infestation in a UK textile mill caused by Dermanyssus gallinae (DeGeer, 1778) (Mesostigmata: Dermanyssidae) special lineage L1

A recurrent mite infestation affecting a room used to inspect fabric in a UK textile mill was investigated to allay concerns of any potential health risks to factory staff, and to inform the unknown risk of downgrading of the product. The approach integrated conventional morphological examination of adult female mites by referring to published identification keys, with molecular speciation based on amplification of a 16S ribosomal DNA fragment. The methods enabled the mites to be unambiguously identified as Dermanyssus gallinae ‘special lineage L1’. Subsequent investigations showed the source of infestation to be pigeons nesting in the air ducts, with the gamasid mites moving into the room once the young birds had fledged. This is the first report of D. gallinae ‘special lineage L1’ in northern Europe. Previous reports of nosocominal gamasoidosis caused by D. gallinae ‘special lineage L1’ originating from feral pigeon populations have been from southern Europe. Confirmation of the mite identity was important in allowing the mill to take remedial and preventive action. In this clinical communication, we provide images of the key morphological features used to identify D. gallinae and describe a molecular protocol to confirm ‘special lineage L1’.     

Age, sexual and seasonal differences of haematological values and antibody status to Chlamydophila sp. in feral and racing pigeons (Columba livia forma domestica) from an urban environment (Zagreb, Croatia)

The aim of this study was to determine the basic haematological parameters in feral and racing pigeons and to compare these parameters according to age, sex and season in healthy feral pigeons as well as between Chlamydophila-serologically positive and negative feral pigeons. Red blood cells (RBC), packed cell volume (PCV), haemoglobin (Hb), mean cell volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), white blood count (WBC), thrombocyte count and differential WBC, were determined in 366 pigeons (Columba livia forma domestica) captured in the City of Zagreb between 1999 and 2002. Of these, 232 feral (179 adult and 53 juvenile, 104 male and 75 female) and 57 racing pigeons (25 male and 32 female) were clinically healthy and bacteriologically and serologically negative, but 77 birds had antibody titres against Chlamydophila sp. Significantly lower values of RBC, PCV, Hb, MCH, WBC and thrombocyte (P<0.05) were observed in young compared to adult pigeons, while the differences in MCV and MCH were not significant between age classes. In differential WBC of young pigeons, a significantly higher percentage of heterophils, eosinophils, basophils and monocytes and a significantly smaller percentage of lymphocytes (P<0.01) was found than in adult pigeons. Significant sex-related differences were seen only in MCV values and in the percentage of lymphocytes (higher in females) and neutrophils (higher in males). PCV, Hb, MCV and MCH increased, while WBC decreased during wintertime (P<0.05). In differential WBC, percentage of heterophils was low in summer and autumn. At the same time, a higher percentage of basophils was found. Low numbers of monocytes were found in summer and low values of eosinophils in winter. In racing pigeons, values of eosinophils and basophils were significantly lower than in feral pigeons. Pigeons which had antibodies against Chlamydophila sp. possessed a higher percentage of monocytes and less lymphocytes than sero-negative animals, while WBC was significant lower than in sero-negative feral pigeons.     

Ticks (Acari: Ixodida) infesting humans in the provinces of Kelkit Valley, a Crimean-congo hemorrhagic fever endemic region in Turkey

Ticks are mandatory blood feeding ectoparasites leading transmission of various tick-borne pathogens to human and animals. Since 2002, thousands of human tick bites and numerous Crimean-Congo Hemorrhagic Fever cases have been reported in several provinces in the Kelkit Valley region in Turkey. Despite increased cases of tick bites and tick-borne diseases, no taxonomic information is available about the tick species infesting humans in the region. In the present study, a tick survey on humans was performed to determine the species composition of ticks infesting humans in several provinces of Kelkit Valley. In the survey, 1,460 ticks (721 males, 516 females and 223 nymphs) were collected from tick-infested humans. A total of 19 tick species have been found on humans in the region, including 7 Hyalomma, 2 Argas, 2 Haemaphysalis, 2 Ixodes, Dermacentor and 3 Rhipicephalus species. Infestation of Dermacentor reticulatus on humans was documented for the first time in Turkey.     

Die Taube – eine Erfolgsgeschichte. Vom Liebling der Götter zur Eroberung der Städte

The pigeon – a success story The pigeon is one of the first animals that man domesticated and it holds a special place in man's affections. The pigeon is far more than an ordinary bird since it is a symbol of different gods and human virtues. In the beginning, the pigeon used to be an ordinary biological creature until it found it's way into man's spiritual world. These associations contribute to man's love and admiration of pigeons. The feral pigeon is a wild descendant of dovecote pigeons and domestic breeds. All experiences up to now lead to the conclusion that reduction of pigeon populations can only be achieved by reducing their food supply. Because of the enormous reproduction rate of the pigeons, killing attempts without any simultaneous food reduction do not have any influence on the number of birds in the population.     

A New Shiga Toxin 2 Variant (Stx2f) from Escherichia coli Isolated from Pigeons

We have isolated Shiga toxin (Stx)-producing Escherichia coli (STEC) strains from the feces of feral pigeons which contained a new Stx2 variant gene designated stx_2f. This gene is most similar to sltIIva of patient E. coli O128:B12 isolate H.I.8. Stx2f reacted only weakly with commercial immunoassays. The prevalence of STEC organisms carrying the stx_2f gene in pigeon droppings was 12.5%. The occurrence of a new Stx2 variant in STEC from pigeons enlarges the pool of Stx2 variants and raises the question whether horizontal gene transfer to E. coli pathogenic to humans may occur.     

Prevalence of <Emphasis Type="Italic">Chlamydophila psittaci</Emphasis> in wild birds—potential risk for domestic poultry,pet birds,and public health?

To determine the prevalence of Chlamydophila psittaci in wild birds, cloacal swabs from 527 songbirds, 442 waterfowl, 84 feral pigeons, and 38 cormorants were examined by Chlamydiaceae-specific real-time polymerase chain reaction (PCR) and ArrayTube microarray assays for chlamydial species determination and genotyping of C. psittaci. Inconclusive cases were further characterized by conventional PCR methods targeting the chlamydial outer membrane protein A, 16S, 23S, and intergenic spacer genes followed by sequencing of the PCR product. Swabs of 19 water birds (tufted ducks and pochards), 12 pigeons, and one songbird were tested positive by the Chlamydiaceae-specific real-time PCR. While C. psittaci genotypes B (n = 5) and E (n = 1) were identified in feral pigeons (n = 9), the genotype could not be identified in the remaining three cases. Sequence data of Chlamydiaceae-positive cases (n = 23; 19 waterfowl, three pigeons, one songbird) indicated the presence of nonclassified chlamydial agents (n = 20) and C. psittaci (n = 3) by 16S rRNA PCR and sequencing. In conclusion, C. psittaci was not detected in waterfowl and songbirds, but C. psittaci proved prevalent in urban feral pigeons, where it poses a significant risk for humans.     

Phoretic dispersal influences parasite population genetic structure

Dispersal is a fundamental component of the life history of most species. Dispersal influences fitness, population dynamics, gene flow, genetic drift and population genetic structure. Even small differences in dispersal can alter ecological interactions and trigger an evolutionary cascade. Linking such ecological processes with evolutionary patterns is difficult, but can be carried out in the proper comparative context. Here, we investigate how differences in phoretic dispersal influence the population genetic structure of two different parasites of the same host species. We focus on two species of host‐specific feather lice (Phthiraptera: Ischnocera) that co‐occur on feral rock pigeons (Columba livia). Although these lice are ecologically very similar, “wing lice” (Columbicola columbae) disperse phoretically by “hitchhiking” on pigeon flies (Diptera: Hippoboscidae), while “body lice” (Campanulotes compar) do not. Differences in the phoretic dispersal of these species are thought to underlie observed differences in host specificity, as well as the degree of host–parasite cospeciation. These ecological and macroevolutionary patterns suggest that body lice should exhibit more genetic differentiation than wing lice. We tested this prediction among lice on individual birds and among lice on birds from three pigeon flocks. We found higher levels of genetic differentiation in body lice compared to wing lice at two spatial scales. Our results indicate that differences in phoretic dispersal can explain microevolutionary differences in population genetic structure and are consistent with macroevolutionary differences in the degree of host–parasite cospeciation.     

Bartonella henselae in eastern Poland: the relationship between tick infection rates and the serological response of individuals occupationally exposed to tick bites

To explore the potential role of Ixodes ricinus as the presumed vector of Bartonella henselae in eastern Poland, ticks collected in various geographic locations were examined for the presence of B. henselae, and the results were matched against the prevalence of anti‐B. henselae antibodies in individuals occupationally exposed to tick bites. The presence of Bartonella DNA was investigated by PCR in a total of 1,603 unfed Ixodes ricinus ticks. The presence of IgG antibodies against B. henselae was investigated in serum samples from 332 people occupationally exposed to tick bites (94 farmers and 238 forestry workers). The total prevalence of B. henselae in ticks was 1.7%; the infection rates in males (3.1%) and females (2.7%) were nearly ten times greater than in nymphs (0.3%). The prevalence of seropositive results in the risk group (30.4%), farmers (27.7%) and forestry workers (31.5%), was significantly greater compared to the control group (8.9%). The results showed a weak positive correlation between the degree of infection of ticks and humans living in the same geographic region. The lack of a direct relationship indicates that exposure to tick bites is only one of the factors contributing to the significant preponderance of a seropositive response to B. henselae in the forestry workers and farmers over the control group. Other factors must be considered, such as contact with cats, which are popular domestic animals in Polish villages, and exposure to cat fleas.     

Screening for several potential pathogens in feral pigeons (<Emphasis Type="Italic">Columba livia</Emphasis>) in Madrid

Background  

Pathogens with the zoonotic potential to infect humans, such as Campylobacter jejuni, Campylobacter coli and Chlamydophila psittaci, can be found in feral pigeons (Columba livia). Given the high density of these birds in the public parks and gardens of most cities, they may pose a direct threat to public health.     

Blood treatment of Lyme borreliae demonstrates the mechanism of CspZ‐mediated complement evasion to promote systemic infection in vertebrate hosts

Lyme disease, caused by the spirochete Borrelia burgdorferi, is the most common vector‐borne disease in the United States and Europe. The spirochetes are transmitted from mammalian and avian reservoir hosts to humans via ticks. Following tick bites, spirochetes colonize the host skin and then disseminate haematogenously to various organs, a process that requires this pathogen to evade host complement, an innate immune defence system. CspZ, a spirochete surface protein, facilitates resistance to complement‐mediated killing in vitro by binding to the complement regulator, factor H (FH). Low expression levels of CspZ in spirochetes cultivated in vitro or during initiation of infection in vivo have been a major hurdle in delineating the role of this protein in pathogenesis. Here, we show that treatment of B. burgdorferi with human blood induces CspZ production and enhances resistance to complement. By contrast, a cspZ‐deficient mutant and a strain that expressed an FH‐nonbinding CspZ variant were impaired in their ability to cause bacteraemia and colonize tissues of mice or quail; virulence of these mutants was however restored in complement C3‐deficient mice. These novel findings suggest that FH binding to CspZ facilitates B. burgdorferi complement evasion in vivo and promotes systemic infection in vertebrate hosts.     

Eumelanin‐based colouration reflects local survival of juvenile feral pigeons in an urban pigeon house

Urbanisation introduces deep changes in habitats, eventually creating new urban ecosystems where ecological functions are driven by human activities. The higher frequency of some phenotypes in urban vs rural/wild areas has led to the assumption that directional selection in urban habitats occurs, which may thereby favour some behavioural and physiological traits in urban animal populations compared to rural ones. However, empirical evidence of directional selection on phenotypic traits in urban areas remains scarce. In this study we tested whether eumelanin‐based colouration could be linked to survival in two urban populations of the feral pigeon Columba livia. A number of studies in different cities pointed out a higher frequency of darker individuals in more urbanised areas compared to rural ones. To investigate whether directional selection through survival on this highly heritable trait could explain such patterns, we conducted mark–recapture studies on two populations of feral pigeons in highly urbanized areas. We predicted that darker coloured individuals would exhibit higher survival and/or philopatry (integrated into ‘local survival’) than paler coloured ones. No difference in local survival was found between adults of different colouration intensities. However, on one site, we found that darker juveniles had a higher local survival probability than light ones. Juvenile local survival on that site was also negatively correlated with the number of chicks born. This suggests the existence of colour‐ and/or density‐dependent selection processes acting on juvenile feral pigeons in urban environments, acting through differential mortality and/or dispersal.     

Impact of urban environment and host phenotype on the epidemiology of Chlamydiaceae in feral pigeons (Columba livia)

Chlamydiaceae are obligate intracellular Gram-negative bacteria found all over the world and known to cause various forms of disease in animals and humans. Urban pigeons are known to be an important reservoir of Chlamydia psittaci, the agent of human psittacosis. In this study, we examined the influence of pigeon houses used to regulate pigeon populations and of melanin-based coloration on several epidemiological parameters of Chlamydiaceae in 708 urban pigeons in Paris. We also identified species and genotypes of Chlamydiaceae present in Parisian populations. First, our results revealed that pigeons roosting and breeding in pigeon houses were equally infected by Chlamydiaceae as those that did not. Second, we found that dark melanic pigeons excreted more Chlamydiaceae than pale melanic ones. Finally, species and strain diversities were very low: all samples were of C. psittaci genotype B. Nevertheless, two atypical Chlamydiaceae were identified based on 16S rRNA and ompA sequences. Our study thus highlights the importance of considering environmental and host phenotype when investigating the epidemiology of infectious diseases.     

Carbonic anhydrase inhibitors: purification and inhibition studies of pigeon (Columba livia var. domestica) red blood cell carbonic anhydrase with sulfonamides

A carbonic anhydrase (CA, EC 4.2.1.1) from red blood cells of pigeons (Columba livia var. domestica), clCA, was purified to homogeneity. Its kinetic parameters for the CO₂ hydration reaction were measured. With a k_cat/K_m of 1.1?×?10⁸ M^?1 s^?1, and a k_cat of 1.3?×?10⁶ s^?1, clCA has a high activity, similar to that of the human isoform hCA II. A group of 25 aromatic/heterocyclic sulfonamides incorporating the sulfanilamide, homosulfanilamide, benzene-1,3-disulfonamide, and acetazolamide scaffolds showed variable inhibitory activity against the pigeon enzyme, with K_Is in the range of 1.9–3460?nM. Red blood cells of pigeons, like those of ostriches, contain thus just one CA isoform, unlike the blood of mammals, which normally contain two isoforms, one of low (CA I-like) and one of very high activity (CA II-like). However, from the sulfonamide inhibition viewpoint, the pigeon enzyme was more similar to hCA II than to the ostrich enzyme.     

Historical and recent evidence for close relationships among Rickettsia parkeri,R. conorii,R. africae,and R. sibirica: Implications for rickettsial taxonomy

Rickettsia parkeri, a member of the spotted fever group rickettsias, was first described in 1939 and was thought to be non‐pathogenic until recently, when it was found to cause a spotted fever‐like illness in humans and areas of necrosis (eschars) at the sites of tick bites. Accordingly, there is currently much interest in this emerging pathogen. In this study, all published articles concerning R. parkeri were reviewed and analyzed for evidence of relatedness among this agent and other spotted fever group (SFG) rickettsiae which also produce similar clinical syndromes and/or eschars, including R. conorii, R. africae, and R. sibirica. A synthesis of the historical (antigenic) and recent (molecular) data supporting a phylogenetic sub‐grouping of these SFG organisms is presented and comments are offered about the taxonomy of rickettsial organisms in general, and R. parkeri in particular.