Infectious Disease: Bedbugs, Lice, and Mites

Bedbugs, mites, and scabies are ectoparasites that commonly affect humans. Bedbugs (Cimex species) were once rare in the United States but are now common. They cause intensely pruritic lesions on areas of exposed skin. The bites are highly allergenic and can cause asthma exacerbations or anaphylaxis. Management of bedbug bites involves symptomatic relief of itching and dealing with patient anxiety. Identification and elimination of infestation are most important. Another ectoparasite of concern is lice (Pediculus and Pthirus species), which causes head, body, and pubic infestations. Patients can experience hypersensitivity to the saliva of lice, but such symptoms often do not develop until several weeks after infestation. Diagnosis involves identification of nits (ie, eggs) or lice on the skin or hair. Several pediculicides are used for management but wet combing without use of pediculicides may be more effective. A third common ectoparasitic infestation, scabies (ie, infestation with the mite Sarcoptes scabiei), affects 5% of the world's population. Patients present with pruritic lesions in skin folds, finger webs, and areas in which clothing is tight. The diagnosis can be confirmed with dermatoscopy or microscopy. Management involves use of permethrin cream, oral ivermectin, or benzyl benzoate.

Parasite spread at the domestic animal - wildlife interface: anthropogenic habitat use, phylogeny and body mass drive risk of cat and dog flea (Ctenocephalides spp.) infestation in wild mammals

BACKGROUND

Spillover of parasites at the domestic animal - wildlife interface is a pervasive threat to animal health. Cat and dog fleas (Ctenocephalides felis and C. canis) are among the world's most invasive and economically important ectoparasites. Although both species are presumed to infest a diversity of host species across the globe, knowledge on their distributions in wildlife is poor. We built a global dataset of wild mammal host associations for cat and dog fleas, and used Bayesian hierarchical models to identify traits that predict wildlife infestation probability. We complemented this by calculating functional-phylogenetic host specificity to assess whether fleas are restricted to hosts with similar evolutionary histories, diet or habitat niches.

RESULTS

Over 130 wildlife species have been found to harbour cat fleas, representing nearly 20% of all mammal species sampled for fleas. Phylogenetic models indicate cat fleas are capable of infesting a broad diversity of wild mammal species through ecological fitting. Those that use anthropogenic habitats are at highest risk. Dog fleas, by contrast, have been recorded in 31 mammal species that are primarily restricted to certain phylogenetic clades, including canids, felids and murids. Both flea species are commonly reported infesting mammals that are feral (free-roaming cats and dogs) or introduced (red foxes, black rats and brown rats), suggesting the breakdown of barriers between wildlife and invasive reservoir species will increase spillover at the domestic animal - wildlife interface.

CONCLUSIONS

Our empirical evidence shows that cat fleas are incredibly host-generalist, likely exhibiting a host range that is among the broadest of all ectoparasites. Reducing wild species' contact rates with domestic animals across natural and anthropogenic habitats, together with mitigating impacts of invasive reservoir hosts, will be crucial for reducing invasive flea infestations in wild mammals.

Simulated environmental transport distances of Lepeophtheirus salmonis in Loch Linnhe, Scotland, for informing aquaculture area management structures

In the majority of salmon farming countries, production occurs in zones where practices are coordinated to manage disease agents such as Lepeophtheirus salmonis. To inform the structure of zones in specific systems, models have been developed accounting for parasite biology and system hydrodynamics. These models provide individual system farm relationships, and as such, it may be beneficial to produce more generalized principles for informing structures. Here, we use six different forcing scenarios to provide simulations from a previously described model of the Loch Linnhe system, Scotland, to assess the maximum dispersal distance of lice particles released from 12 sites transported over 19 day. Results indicate that the median distance travelled is 6.1 km from release site with <2.5% transported beyond 15 km, which occurs from particles originating from half of the release sites, with an absolute simulated distance of 36 km observed. This provides information suggesting that the disease management areas developed for infectious salmon anaemia control may also have properties appropriate for salmon lice management in Scottish coastal waters. Additionally, general numerical descriptors of the simulated relative lice abundance reduction with increased distance from release location are proposed.

New Introductions, Spread of Existing Matrilines, and High Rates of Pyrethroid Resistance Result in Chronic Infestations of Bed Bugs (Cimex lectularius L.) in Lower-Income Housing

Infestations of the common bed bug (Cimex lectularius L.) have increased substantially in the United States in the past 10–15 years. The housing authority in Harrisonburg, Virginia, conducts heat-treatments after bed bugs are detected in a lower-income housing complex, by treating each infested unit at 60°C for 4–6 hours. However, a high frequency of recurrent infestations called into question the efficacy of this strategy. Genetic analysis using Bayesian clustering of polymorphic microsatellite loci from 123 bed bugs collected from 23 units from May 2012 to April 2013 in one building indicated that (a) 16/21 (73%) infestations were genetically similar, suggesting ineffective heat-treatments or reintroductions from within the building or from a common external source, followed by local spread of existing populations; and (b) up to 5 of the infestations represented new genotypes, indicating that 5 new populations were introduced into this building in one year, assuming they were not missed in earlier screens. There was little to no gene flow among the 8 genetic clusters identified in the building. Bed bugs in the U.S. often possess one or both point mutations in the voltage-gated sodium channel, termed knockdown resistance (kdr), from valine to leucine (V419L) and leucine to isoleucine (L925I) that confer target-site resistance against pyrethroid insecticides. We found that 48/121 (40%) bed bugs were homozygous for both kdr mutations (L419/I925), and a further 59% possessed at least one of the kdr mutations. We conclude that ineffective heat treatments, new introductions, reintroductions and local spread, and an exceptionally high frequency of pyrethroid resistance are responsible for chronic infestations in lower-income housing. Because heat treatments fail to protect from reintroductions, and pesticide use has not decreased the frequency of infestations, preventing new introductions and early detection are the most effective strategies to avoid bed bug infestations in multistory apartment buildings.

Bed bugs

The term bed bug is applied to 2 species of genus Cimex: lectularius describes the common or temperate bed bug, and hemipterus its tropical cousin. Cimex lectularius is aptly named; its genus and species derive from the Latin words for bug and bed, respectively. Though the tiny pest is receiving increased public attention and scrutiny, the bed bug is hardly a new problem.

Canine and feline parasitic zoonoses in China

Canine and feline parasitic zoonoses have not been given high priority in China, although the role of companion animals as reservoirs for zoonotic parasitic diseases has been recognized worldwide. With an increasing number of dogs and cats under unregulated conditions in China, the canine and feline parasitic zoonoses are showing a trend towards being gradually uncontrolled. Currently, canine and feline parasitic zoonoses threaten human health, and cause death and serious diseases in China. This article comprehensively reviews the current status of major canine and feline parasitic zoonoses in mainland China, discusses the risks dogs and cats pose with regard to zoonotic transmission of canine and feline parasites, and proposes control strategies and measures.

[Flea and tick control in dogs and cats]

Fleas and ticks may cause skin problems in dogs and cats and transmit (zoonotic) diseases. This is an overview about the present situation of the ectoparasites control.

Sea louse infection of juvenile sockeye salmon in relation to marine salmon farms on Canada's west coast

BACKGROUND

Pathogens are growing threats to wildlife. The rapid growth of marine salmon farms over the past two decades has increased host abundance for pathogenic sea lice in coastal waters, and wild juvenile salmon swimming past farms are frequently infected with lice. Here we report the first investigation of the potential role of salmon farms in transmitting sea lice to juvenile sockeye salmon (Oncorhynchus nerka).

METHODOLOGY/PRINCIPAL FINDINGS

We used genetic analyses to determine the origin of sockeye from Canada's two most important salmon rivers, the Fraser and Skeena; Fraser sockeye migrate through a region with salmon farms, and Skeena sockeye do not. We compared lice levels between Fraser and Skeena juvenile sockeye, and within the salmon farm region we compared lice levels on wild fish either before or after migration past farms. We matched the latter data on wild juveniles with sea lice data concurrently gathered on farms. Fraser River sockeye migrating through a region with salmon farms hosted an order of magnitude more sea lice than Skeena River populations, where there are no farms. Lice abundances on juvenile sockeye in the salmon farm region were substantially higher downstream of farms than upstream of farms for the two common species of lice: Caligus clemensi and Lepeophtheirus salmonis, and changes in their proportions between two years matched changes on the fish farms. Mixed-effects models show that position relative to salmon farms best explained C. clemensi abundance on sockeye, while migration year combined with position relative to salmon farms and temperature was one of two top models to explain L. salmonis abundance.

CONCLUSIONS/SIGNIFICANCE

This is the first study to demonstrate a potential role of salmon farms in sea lice transmission to juvenile sockeye salmon during their critical early marine migration. Moreover, it demonstrates a major migration corridor past farms for sockeye that originated in the Fraser River, a complex of populations that are the subject of conservation concern.

Sea lice, Lepeophtheirus salmonis, transfer between wild sympatric adult and juvenile salmon on the north coast of British Columbia, Canada

We examine sea lice, Lepeophtheirus salmonis, on juvenile and adult salmon from the north coast of British Columbia between 2004 and 2006 in an area that does not at present contain salmon farms. There is a pronounced zonation in the abundance of L. salmonis on juvenile pink salmon, Oncorhynchus gorbuscha, in the Skeena and Nass estuaries. Abundances in the proximal and distal zones of these estuaries are 0.01 and 0.05 respectively. The outer zones serve as feeding and staging areas for the pink salmon smolts. Returning Chinook, Oncorhynchus tshawytscha, and coho salmon, Oncorhynchus kisutch, concentrate in these areas. We collected data in 2006 to examine whether L. salmonis on returning adult salmon are an important source of the sea lice that appear on juvenile pink salmon. Nearly all (99%) of the sea lice on returning Chinook and over 80% on coho salmon were L. salmonis. Most of the L. salmonis were motile stages including many ovigerous females. There was a sharp increase in the abundance of sea lice on juvenile pink salmon smolts between May and July 2006 near the sites of adult captures. As there are no salmon farms on the north coast, few sticklebacks, Gasterosteus aculeatus, and very few resident salmonids until later in the summer, it seems that the most important reservoir of L. salmonis under natural conditions is returning adult salmon. This natural source of sea lice results in levels of abundance that are one or two orders of magnitude lower than those observed on juvenile pink salmon in areas with salmon farms such as the Broughton Archipelago.

Ectoparasites of commensal rodents in Talkha Center, Dakahlia Governorate, Egypt

The ecto-parasites infesting commensally rodents were collected from the different localities in Talkha Center (Dakahlia Governorate) from April 2006 to March 2007. The seasonal abundance of rodent number and rat index was 52 (0.58) in spring, 27 (0.3) in summer, 39 (0.22) in autumn and 17 (0.05) in winter. From 135 rodent species and rat index was Rattus norvegicus N=33 (0.24), R. r. frugivorous N=39 (0.29); R. r. alexandrinus N=48 (0.36) and Mus musculus N=15 (0.11). From 388 ecto-parasite infested rodent collected number and ecto index was fleas N= 114 (0.84 flea/rat), Lice N=93 (0.69 lice/rat), Mites N = 165 (1.2 mite/rat) and larva of ticks N=16 (0.12 tick/rat). No doubt, rodents and their ectoparasites played a serious role in spreading and transmission of zoonotic diseases to human and animal.

Parasitology and urban livestock farming in nigeria: prevalence of ova in faecal and soil samples and animal ectoparasites in Makurdi

Domestic environmental pollution resulting from urban livestock farming was investigated in Makurdi using parasitological techniques. The test tube flotation technique was used for the parasitological analysis of animal faecal matter and soil samples collected from residential premises. Ectoparasitic fauna of dogs, goats, sheep and cattle cohabiting with humans within the same residential compound were also collected and identified. The hand-picking and body brushing methods were employed to search for ticks, fleas, lice and mites. Of the 150 soil samples examined, 55 (36.7 %) were positive for 1 or more eggs of helminth parasites. There was no significant difference in the distribution of eggs in the soil samples from the 3 areas sampled (Chi2 = 0.046, df = 2, P > 0.05). Ascaris species were the dominant parasite eggs found. Of the 180 faecal samples examined, 107 (59.4 %) were positive for 1 or more eggs of helminth parasites. Chi-square analysis showed no significant difference in the level of infection of different animal faeces sampled (Chi2 = 5.74, df = 4, P > 0.05). Ascaris species were again the dominating helminth parasite eggs found. There was also no significant difference in the prevalence of helminth eggs in the animal faecal samples from the 3 areas sampled (Chi2 = 5.99, df = 4, P > 0.05). A total of 1908 ectoparasites was recovered (ticks: 32.80 %; lice: 22.43 %; fleas: 22.06 % and mite: 22.69 %). There was no significant difference in infestation animals between sexes (Chi2 = 0.10, df = 4, P > 0.05). The predominant genus encountered for ticks were Amblyomma, while Linognathus (43.90 %), Ctenocephalides (97.38 %) and Sarcoptes (58.89 %) were most predominant for lice, fleas and mites respectively. The public health implications of the findings, especially as these relate to the increasing incidence and prevalence of zoonotic infections, are discussed.

Cercarial dermatitis in Austria: questionnaires as useful tools to estimate risk factors?

Cercarial dermatitis is a worldwide occurring skin disease characterized by itching and skin papulation. It is caused by cercariae of the fluke family Schistosomatidae. In the tropics and subtropics species of the genus Schistosoma can cause severe diseases of man. However, several genera (e.g. Trichobilharzia, Bilharziella) of medical significance are prevalent in Europe as well; they are also known as "bird schistosomes", because waterfowl is the final host. Pulmonate snails act as intermediate hosts. Humans are accidental hosts; they get infested by penetration of the cercariae into the skin of swimmers/bathers in ponds and lakes. They can not mature in humans, but die shortly after penetration. Cercarial dermatitis is known in Austria since 1969, with regularly occurrences nearly every summer. In early 2003 we created a homepage to provide information about the causative agents for the public/patients, to document the occurrences and to get data about the distribution of this parasitic disease. We therefore created a questionnaire and asked people for the following parameters: personal data, information about the waters, activity in the water and details about the dermatitis itself. A total of 34 questionnaires were returned. The results will be discussed according to their relevance as risk factors. The way how people interact with the water seems to be essential, but not demographic features. In addition, this approach revealed a new segment of the public that is at risk - owners/users of swimming ponds.

Infestation of Wistar rats with Tunga penetrans in different microenvironments

Tungiasis is a zoonotic ectoparasitosis that causes considerable morbidity in affected populations. The type of microenvironment that facilitates infestation of hosts by Tunga penetrans has not been investigated. In this study, we exposed 30 laboratory-raised Wistar rats, a suitable model for the infestation, at six different places characterized by different microenvironments in a hyperendemic fishing village in northeastern Brazil. During a period of two weeks, the animals were monitored and the number of embedded fleas was documented. The number of lesions varied considerably according to the microenvironment and was highest in a cage placed at the far end of a compound of a household affected by tungiasis. No penetration was observed inside houses. Results indicate that in this endemic area transmission of T. penetrans seems to occur mainly outdoors.

DENSITY-DEPENDENT TOPOGRAPHICAL SPECIALIZATION IN GYRODACTYLUS ANISOPHARYNX (MONOGENOIDEA, GYRODACTYLIDAE): BOOSTING TRANSMISSION OR EVADING COMPETITION?

Viviparous gyrodactylids are remarkable monogenoid ectoparasites, not only because of their speciousness, but also due to their unusually wide range of hosts. Although many factors have been proposed to determine the location where gyrodactylids attach to their hosts, little is known about how their preference for specific host body regions changes over the course of infection. In this study, we investigate the dynamics of topographical specialization of the parasite Gyrodactylus anisopharynx on 2 of its natural freshwater fish hosts (Corydoras paleatus and C. ehrhardti), as well as a naïve host (C. schwartzi). We recorded the spatial location of this parasite from the foundation of the infrapopulation to its extinction to assess how topographical specialization is affected by host species, the size and the age of the infrapopulation, and the possibility of transmission among hosts. Our results indicate that topographical specialization is negatively correlated with infrapopulation size and only marginally affected by infrapopulation age. Also, the degree of specialization was different among host species, but seemed unaffected by the possibility of transmission among hosts. Therefore, observed changes in spatial specialization of G. anisopharynx do not appear to represent adaptive responses to maximize their transmission. Rather, mechanisms such as increased competition and/ or local immune responses might cause parasites to occupy less favorable regions of the body of their hosts with increasing density.

[The effects of global climatic changes on bloodsucking ectoparasites and pathogens they transmit]

The present global climatic changes, regardless of their causes and duration, are of paramount importance from the ecological perspective. The influence of these changes on Russian population health attracts the attention of experts. The most important changes have already taken place in the high and middle latitudes, occupied by Russia. The article covers a probable impact of global changes on the distribution of bloodsucking arthropods as the vectors of inoculable disease agents, their abundance and vector capacity, and the role of migratory birds in their spreading. For Russia, the most important is to forecast the condition of the population of gnats, malaria vectors in particular, as well as ticks, the latter group being the vectors of tickborne infections ranging from the Baltic Sea to the Pacific Ocean. Analysis of the changes in mean annual temperatures during the past century by the example of Minsk, an East European city, demonstrates its nearly 1.5-fold increase. Minsk in Belarus, as well as many big cities in Russia, such as St. Petersburg, Yekaterinburg etc., present the so called "warm islands". Global increase in temperatures, winter ones first of all, especially in megapolises, leads to outbreaks of inoculable diseases transmitted by bloodsucking vectors in urbanized territories, with a noticeable north shift of their natural ranges. Recent epidemics of West Nile fever in New York City, USA, as well as in Krasnodar and Volgograd, Russia, can serve as examples. Increased mean summer temperatures, as well as prolonged warm and humid periods, facilitate malaria transmissions. The periods of possible successful transmission of tick-borne infections is prolonged likewise, with a north-west shift of their ranges. Thus, Japanese encephalitis outbreaks are expected in Russian Primorye and in the south of Sakhalin Island. Among known and still revealed tick-borne diseases, an increased role is going to be played by mixed viral as well as bacterial infections.

[Diagnosis of major sexually transmitted infections in the doctor's office: ectoparasites and yeasts]

Ectoparasites, such as lice and itch mites (scabies) as well as yeasts, may be transmitted not only by sexual contact, but also by less intimate skin contact. The nits of the louse are visible to the naked eye, while Candida albicans is detected under the microscope or by culture.

ECTOPARASITES AND OTHER EPIFAUNISTIC ARTHROPODS OF SYMPATRIC COTTON MICE AND GOLDEN MICE: COMPARISONS AND IMPLICATIONS FOR VECTOR-BORNE ZOONOTIC DISEASES

Ectoparasite and epifaunistic arthropod biodiversity and infestation parameters were compared between 2 sympatric small rodent species, the cotton mouse (Peromyscus gossypinus (Le Conte)) and golden mouse (Ochrotomys nuttalli (Harlan)), in southern Georgia from 1992 to 2003. Because the cotton mouse is known to be a reservoir of more vector-borne zoonotic pathogens than the golden mouse, we hypothesized that it would be parasitized by more ectoparasites that are known to be vectors of these pathogens. Cotton mice (n = 202) were parasitized by 19 species of arthropods, whereas golden mice (n = 46) were parasitized by 12 species. Eleven species of arthropods were recovered from both host species, whereas 7 were recorded only from cotton mice, and 1 species only from golden mice. Infestation prevalences (percent of mice parasitized) were significantly higher for 1 species of arthropod (the tropical rat mite Ornithonyssus bacoti (Hirst)) infesting cotton mice and for 4 species (the flea Peromyscopsylla scotti Fox and the mites Glycyphagus hypudaei Koch, Androlaelaps casalis (Berlese), and Androlaelaps fahrenholzi (Berlese)) infesting golden mice. Mean intensities (mean per infested mouse) were significantly higher for 2 species (the flea Orchopeas leucopus (Baker) and the blacklegged tick Ixodes scapularis Say) infesting cotton mice and for 2 species (G. hypudaei and A. fahrenholzi) infesting golden mice. Ectoparasites that are known to be vectors of zoonotic pathogens were significantly more common on cotton mice than on golden mice. These ectoparasites included the rhopalopsyllid flea Polygenis gwyni (Fox), a vector of the agent of murine typhus; I. scapularis, the principal vector of the agents of Lyme borreliosis, human granulocytic ehrlichiosis, and human babesiosis; and O. bacoti, a laboratory vector of several zoonotic pathogens. However, 2 species of ixodid ticks that can transmit zoonotic pathogens were recovered from both host species. These were the American dog tick Dermacentor variabilis (Say), the principal vector of the agent of Rocky Mountain spotted fever in eastern North America, and Ixodes minor Neumann, an enzootic vector of the agent of Lyme borreliosis. Overall, the cotton mouse was parasitized by significantly more ectoparasites that are known to be vectors of zoonotic pathogens than was the golden mouse. These data support the hypothesis that the cotton mouse has greater epidemiological importance for zoonotic vector-borne pathogen transmission than does the golden mouse.

High attack rate of Tunga penetrans (Linnaeus 1758) infestation in an impoverished Brazilian community

Tungiasis (jigger) is endemic in many impoverished communities in many parts of Brazil. Forty-seven individuals entering an endemic area were followed up for a period of six weeks and regularly examined for the presence of newly embedded sand fleas. At the end of the third week, the attack rate of Tunga penetrans infestation had already approached 100%.

Zoonotic skin diseases of dogs and cats

Although there are over 250 zoonotic diseases, only 30-40 of them involve dogs and cats. Transmission of zoonotic infections occurs via bites, scratches or touch; exposure to saliva, urine or feces; inhalation of particles or infectious aerosols; contact with a transport or intermediate host (e.g. ticks, fleas); or exposure to contaminated water, soil or vegetation. This paper summarizes the most important common zoonotic dermatological diseases of dogs and cats. The most common dermatological zoonoses are flea and tick infestations and the diseases they transmit; dermatophytosis; and mite infestations (Sarcoptes and Cheyletiella). Prevention of zoonotic infestations or infections can be accomplished easily by the use of routine flea and tick control, screening of new pets for dermatophytosis, and routine hand-washing.

[Humanopathogenic parasites--an unwelcome import]

Humanopathogenic parasites represent a health risk for travelers to tropical countries. They can be picked up by direct contact, via contaminated food and drink, the bites of blood-sucking insects and leeches, as also via direct penetration through the skin. Not only the bite and sting wounds themselves are unpleasant. The true danger to the victim is represented, in particular, by the bacteria, viruses or parasites that are transmitted in this way. They can give rise to protracted diseases such as hepatitis B, cutaneous or intestinal disorders. The most effective preventive measure is exposure prophylaxis.

Mitochondrial DNA variation of Gyrodactylus spp (Monogenea, Gyrodactylidae) populations infecting Atlantic salmon, grayling, and rainbow trout in Norway and Sweden

Approximately 800 bp of the mitochondrial cytochrome oxidase I (COI) gene were sequenced from 76 Gyrodactylus specimens of 32 salmonid host populations, i.e. from Salmo salar, Thymallus thymallus, and Oncorhynchus mykiss in Norway, Sweden and Latvia. The COI sequences indicated a substantial intraspecific differentiation of Gyrodactylus salaris and Gyrodactylus thymalli. In total, 12 haplotypes were identified which group into five well supported clades, three clades with parasites from Atlantic salmon and two clades with parasites from grayling. The basal nodes linking the five clades together are only weakly supported. Thus, there is no support for the monophyly of all G. salaris haplotypes and the monophyly of all G. thymalli haplotypes. The lack of monophyly of the mitochondrial haplotypes of G. salaris and G. thymalli may indicate that G. salaris and G. thymalli represent (i). two polytypic species or (ii). one polytypic species, or (iii). refer to a complex of more than two sibling species. The mtDNA data indicate multiple introductions of G. salaris and G. thymalli into Norway. A minimum of three independent introductions of G. salaris and two independent introductions of G. thymalli are supported. This is congruent with earlier hypotheses on the introduction of G. salaris and G. thymalli into Norway.

Human infestation by pigeon fleas (Ceratophyllus columbae) from feral pigeons

The report concerns a married couple who were repeatedly invaded by pigeon fleas (Ceratophyllus columbae) over a period of 2 months. The source of the fleas was a pair of breeding feral pigeons (Columba livia). The birds' nest was located in the attic immediately above the couple's apartment, and the fleas found their way along an unsealed heating pipe. The people encountered up to 40 bites per night. With invasions repeated almost every night, the man gradually developed an allergic urticarial reaction. The most traumatic experience for the couple, however, was to learn that they were invaded by fleas (initially, they had presumed they were bothered by mosquitoes). This information resulted in severe psychological distress with phobic reactions and insomnia. Despite the successful removal of the fleas and the pigeons that were source of the pest, parasitophobia of the man persisted over the following 4 months. This case is discussed from the broader aspect of health risks related to feral pigeons and animal fleas. Also summarised are previous observations on people invaded by pigeon fleas.

Interspecific parasite exchange in a mixed colony of birds

Studies of avian host-parasite interactions rarely include consequences of relationships among hosts for either the host or parasite species. In this study, we examine the ectoparasitic burden of adult and nestling European bee-eaters (Merops apiaster) and rock sparrows (Petronia petronia) in a mixed colony. We found that (1) each bird species had its own species of lice; (2) hematophagous mites parasitized both adults and nestlings of both bird species; (3) Carnus hemapterus, a common parasite of nestling bee-eaters, also infested rock sparrow nestlings, a species not previously described as a host for this dipteran; and (4) whereas C. hemapterus did not show high host specificity within the colony, the emergence of adult flies was synchronized with the start of hatching in bee-eater nests. We suggest that coexistence of these 2 bird species results in parasite exchange, bee-eaters obtaining mites from sparrows and sparrows becoming infested by C. hemapterus. Differences in the detrimental effects of parasite transfer for each host species may result in a process of apparent competition mediated by shared parasites. Interspecific parasite exchange is an important aspect of host-parasite relationships in mixed colonies, which requires further attention.

Progress toward molecular characterization of ectoparasite modulation of host immunity

Ectoparasitic arthropods and vector-borne infectious agents are global medical and veterinary public health concerns. Economic impact due to direct effects of infestation and disease transmission are significant. These problems are increased by development of arthropod resistance to insecticides/acaricides; drug resistance of vector-borne pathogens; and, lack of effective vaccines to prevent many of these diseases. There is much to be gained from understanding the complex array of immunological interactions occurring at the arthropod-host-pathogen interface. One application of that knowledge is the development of novel vaccines for the control of both ectoparasitic arthropods and the diseases they transmit. We now realize that blood-feeding arthropods are not simply flying or crawling hypodermic needles and syringes. Ectoparasitic arthropods are not passive partners in their relationships with the immune systems of their hosts. These clever invertebrates produce numerous pharmacologically active molecules that help them migrate through tissues of their hosts or to successfully obtain blood meals. Arthropod parasites stimulate a spectrum of host immune responses that could potentially impair development, reduce feeding success, or kill the ectoparasite. Not unexpectedly, arthropods have developed sophisticated arsenals of countermeasures that modulate or deviate host immune responses. Not only does arthropod modulation of host immunity facilitate survival in tissues or increase the likelihood of obtaining a blood meal, but it is increasingly recognized as a critical factor in pathogen transmission. Those countermeasures to host immune defenses are the topics of this review. Emphasis is placed on our current understanding of the molecular bases of those changes; the molecules responsible for host immunomodulation; contemporary approaches for studying these complex relationships; and, the potential for using this information to develop innovative vaccine-based control strategies.

Health protocol for translocation of free-ranging elk

When considering an elk (Cervus elaphus) restoration program, wildlife managers must evaluate the positive and negative elements of translocation. We prepared this protocol to give an overview of health considerations associated with translocation of elk, with an emphasis on movement of free-ranging elk from western North America to the southeastern USA. We evaluated infectious agents and ectoparasites reported in elk from two perspectives. First, we made a qualitative estimate of the ability of the agent to be introduced and to become established. This was done using a selected set of epidemiologic factors. Second, if there was a good possibility that the organism could become established in the release area, the potential pathological consequences for elk and other wildlife, domestic animals, and humans were assessed via examination of the literature and consultation with other animal health specialists. The results of these evaluations were used to classify infectious agents and ectoparasites as low risk (n = 174), unknown risk (n = 10), and high risk (n = 9). We classified Anaplasma marginale, Anaplasma ovis, Mycobacterium paratuberculosis, Pasteurella multocida serotype 3, Elaphostrongylus cervi, Dicrocoelium dendriticum, Fascioloides magna, Echinococcus granulosus, Dermacentor albipictus, and Otobius megnini as unknown risks. High risk infectious agents and ectoparasites were the agent of chronic wasting disease, Brucella abortus, Mycobacterium bovis, Dermacentor andersoni, Ixodes pacificus, and Psoroptes sp. Parelaphostrongylus tennis, Elaeophora schneideri, and a Babesia sp. are parasites endemic in the southeastern USA that may present a "reverse risk" and adversely affect elk if released in some parts of the region. We developed a five-component protocol to reduce the risk of introduction of high risk infectious agents and ectoparasites that included: (1) evaluation of the health status of source populations, (2) quarantines, (3) physical examination and diagnostic testing, (4) restrictions on translocation of animals from certain geographic areas or populations, and (5) prophylactic treatment.

Association between nutritional indicators and infectivity of dogs seroreactive for Trypanosoma cruzi in a rural area of northwestern Argentina

The association between the nutritional state of mongrel dogs naturally infected with Trypanosoma cruzi and their infectivity to Triatoma infestans bugs and immune response to Trypanosoma cruzi were studied in the rural village of Amamá, northwestern Argentina. All of the 97 evaluated dogs were classified into one of three categories of external clinical aspect (ECA) based on the degree of muscle development, external evidence of bone structures, state of the hair of the coat, existence of fatty deposits, and facial expression. ECA was significantly associated with two nutritional indicators, hematocrit and skin-fold thickness, but not with total serum proteins. For all dogs, hematocrit was significantly correlated with skin-fold thickness. The 2-year survival probability decreased significantly from 60.7% for dogs with good ECA to 45.9% and 31.2% for those with regular and bad ECA, respectively. The age-adjusted relative odds of infection for Triatoma infestans xeno-diagnosis nymphs that fed once on a dog seroreactive for Trypanosoma cruzi decreased significantly as ECA improved, when tested by multiple logistic regression analysis. A delayed hypersensitivity reaction was observed in all of the seroreactive dogs with good ECA but only in 45-50% of those with regular or bad ECA. Dogs with bad ECA had a 2.6 and 6.3 times greater probability of infecting triatomines after a single full blood meal than dogs with regular or good ECA, respectively. Our study shows that the reservoir competence of dogs for Trypanosoma cruzi was associated with ECA, which is a surrogate and valid index of nutritional state.

Ectoparasites of dogs belonging to people in resource-poor communities in North West Province, South Africa

A total of 344 dogs belonging to people in resource-poor communities in North West Province, South Africa, was examined for ectoparasites, and all visible arthropods were collected from the left side of each dog. By doubling these numbers it was estimated that the dogs harboured 14,724 ixodid ticks, belonging to 6 species, 1,028 fleas, belonging to 2 species, and 26 lice. Haemaphysalis leachi accounted for 420 and Rhipicephalus sanguineus for 14,226 of the ticks. Pure infestations of H. leachi were present on 14 dogs and of R. sanguineus on 172 dogs. Small numbers of Amblyomma hebraeum, R. appendiciulatus, R. evertsi evertsi and R. simus were also collected. The predominance of R. sanguitneus accounts for the high prevalence of canine ehrlichiosis (Ehrlichia canis) within the survey region, compared to canine babesiosis (Babesia canis), which is transmitted by H. leachi, and is a much rarer disease.

Infection and seroconversion of cats exposed to cat fleas (Ctenocephalides felis Bouché) infected with Rickettsia felis

Cats with no prior exposure to cat fleas were exposed to fleas infected with Rickettsia felis and monitored monthly for seroconversion via an indirect fluorescent assay (IFA). Each of 12 cats continually infested with fleas, seroconverted by four months post-exposure. Three of six cats fed on by 50 fleas for 15 minutes once per week also seroconverted by month four. Rickettsia felis DNA was detected by PCR in the blood of five of the 16 cats.

Dionchus postoncomiracidia (Monogenea: Dionchidae) from the skin of blacktip sharks, Carcharhinus limbatus (Carcharhinidae)

Postoncomiracidia of Dionchus sp. are described from specimens collected from the skin of 2 blacktip sharks Carcharhinus limbatus, captured in the northern Gulf of Mexico. The parasites resemble nonciliated oncomiracidia hatched from eggs laid by Dionchus sp. on gills of a cobia Rachycentron canadum and adults of Dionchus remorae that were collected from gills of a common sharksucker Echeneis naucrates, captured in association with a third blacktip shark. The hamuli of the postoncomiracidia were morphologically similar to those of adult D. remorae. This is the first report of dionchids from an elasmobranch and from a location other than the gills. These findings support the idea that some dionchid oncomiracidia colonize the skin of sharks or other aquatic vertebrates that sponsor remoras, prior to transferring to other remoras and maturing.

[Farm animals as disease vectors of parasitic epizoonoses and zoophilic dermatophytes and their importance in dermatology]

Different pest arthropods and dermatophytes occurring primarily in farm animals may be transmissible to man and produce human dermatoses. The movement and cutaneous penetration habits of external parasites often cause crusted papules, severe itching and dermatitis or may damage their hosts by blood-sucking or by sensitizing them to their saliva. Furthermore different dermatophytes should be considered a possible cause of human skin lesions. Farm animals (cattle, pig, poultry, and rabbit) can transmit external parasites (ticks: Ixodes ricinus, Argas reflexus; fleas: Ceratophyllus gallinae, Spilopsyllus cuniculi, and mites: Sarcoptes scabiei var. bovis, Sarcoptes scabiei var. suis, Dermanyssus gallinae, Cheyletiella parasitovorax), and dermatophytes (Trichophyton sp., and Microsporum sp.). People who have close contact to infested farm animals are more often exposed to epizoonotic infections. Certain professions, such as farmers, and veterinarians, are especially vulnerable.

[The possible consequences of the probable global warming of the climate for the spread of blood-sucking ectoparasites and the pathogens they transmit]

The paper reviews the causes and possible consequences of the warming-up of global climate. Probable changes in the areas of vectors and blood-suckers, which are most important for Russia, are analyzed. The vectors of malaria and tick-borne pathogens were used as special subjects of prognostic survey. The paper shows it necessary to computer-aided simulate possible consequences of climatic warming-up for changes in the parasitological situation in the Russian Federation.

[Cutaneous zoonoses transmitted by dogs and cats]

Pets like dogs and cats are responsible for a series of zoonotic disorders. Some of these diseases are inflicted by bites, scratches or licking. Others result from a close contact with fur, or are transmitted by ectoparasites or by the contaminated environment. Some systemic infectious and parasitic diseases are transmitted from animals to humans and vice versa. Such situation may lead to endemic problems in some communities.

High host specificity of Crataerina melbae (Diptera: Hippoboscidae) in a mixed colony of birds

We looked for louse flies (Diptera, Hippoboscidae) in a mixed colony of 9 species of birds from 1991 to 1997. Alpine swifts (Apus melba) exhibited an unusually high prevalence (85.9%) by Crataerina melbae (Rondani, 1879). No birds from the other 8 breeding bird species were parasitized by this louse fly. We suggest that the number of potential swiftlike hosts as well as the size of hosts may account for the differential prevalence of the louse flies within the colony.

Human zoonotic infections transmitted by dogs and cats

Dogs and cats are the 2 most common household pets. However, they may be a direct or indirect source of human infections. This article aims to familiarize physicians with some common and uncommon bacterial, rickettsial, parasitic, and fungal zoonotic infections of dogs and cats. Animal bites with or without infection continue to be a common problem. Treatment of infected animal bites must include early debridement and concern for organisms from the mouth flora of the animal. The diagnosis and treatment of cat-scratch disease have become easier since Bartonella henselae has been established as the main causal agent. Less common bacterial and rickettsial zoonotic infections are included to increase the reader's awareness. Parasitic infections, such as creeping eruptions, visceral larva migrans, cryptosporidiosis, and toxoplasmosis, are diseases associated with contact with dogs and cats. Pets can also be the source of dermatophyte infections. An increase in awareness that some of these diseases may be associated with animals could provide a better plan for the prevention and treatment of common and uncommon zoonotic infections.

Cutaneous myiasis in a traveller returning from Africa

Cutaneous myiasis is seen in travellers returning from the tropics. The flies commonly involved are Cordylobia arthropophaga and Dermatobia hominis. Humans become infected by contact with eggs laid by the female fly on soil or contaminated clothing. The clinical presentation is boil-like skin lesions. Treatment involves asphyxiation of larvae forcing emergence, application of toxic agents or surgical removal.

Interhost movement of adult cat fleas (Siphonaptera: Pulicidae)

Adult cat fleas, Ctenocephalides felis (Bouché), marked with orange-red or green fluorescent dye were released on one cat to study movement to another cat over a 7-d period. When the cats were separated, 3-8% of the marked fleas moved to the other cat. When the cats were allowed to remain together, 2-15% of the fleas moved. The percentage of fleas unaccounted for ranged from 8-47%. When both cats lived together, 8-15% movement occurred no matter which cat was infested. The percentage of female and male fleas unaccounted for was 8-32 and 30-47%, respectively, highlighting the importance of host grooming. Significantly fewer female cat fleas moved from one host to another than did males. The likelihood of establishing new infestations by adult fleas transferring from one host to another exists. However, visitations to environments capable of supporting immature stages of fleas seem a more important source of flea infestations.

Arthropoda as zoonoses and their implications

Some aspects of changing patterns of arthropodal infections and arthropod-borne diseases in Mediterranean areas are briefly discussed. Selected examples are given, with particular emphasis on the phenomenon of the synanthropic flea Ctenocephalides felis felis and on health problems caused by human infections with Argas reflexus, the common tick of urban pigeons in Europe. Finally, the risk of the emergence of Lyme borreliosis (Borrelia burgdorferi) is considered in relation to the increasing spread of environmental infestation with ticks, mainly Ixodes ricinus, an efficacious vector for the spirochaete.

[The role of companion animals in the spread of zoonoses of parasitic origin]

This paper provides parasitological data necessary to the epidemiology of the major parasitic zoonoses transmitted by companion animals. Possible modes of contamination of humans are reviewed, along with various factors linked to parasites, host animals and human beings in the spread of zoonoses.

Nosocomial transmission and infection control aspects of parasitic and ectoparasitic diseases. Part III. Ectoparasites/summary and conclusions

As a rule, both the standard of hygiene and sanitation prevalent in hospitals in the United States and the rarity of parasitic diseases compared to viral, bacterial, and fungal infections, reduce the hazard of nosocomial acquisition of parasites to relatively trivial levels. However, abetted by the resultant low index of suspicion on the part of clinical staff, certain parasitic microorganisms may at times cause significant morbidity and even mortality in both normal and immunocompromised patients, as summarized in this review. Also, the nosocomial acquisition of parasites may be somewhat underappreciated because the incubation period for clinical illness may be days to weeks and thus a hospital-acquired infection may not be recognized as such, particularly if the parasite is endemic locally. Parasitic diseases have been a much more significant problem in certain special facilities, such as custodial institutions for the mentally ill or retarded, where crowding, poor environmental sanitation, and low levels of personal hygiene have in the past allowed the rapid dissemination and endemic occurrence of a large variety of parasitic infections. It is likely that nosocomial transmission of parasites may be an even greater problem in some hospitals in the tropics, where strict hygienic standards are costly or otherwise more difficult to maintain, and where often an increased proportion of the patient population harbors one or more parasites. However, the exact magnitude of the problem in tropical hospitals is also more difficult to determine because nosocomial acquisition of a parasitic infection may not be distinguished easily versus exogenous infection or reactivation of latent infection.(ABSTRACT TRUNCATED AT 250 WORDS)

[Population contacts in the Republic of Guinea with ectoparasites and rodents based on questionnaire data. 1. The tasks and the scope of the questionnaire]

Questionnaire is presented which was used in 1987 in 15 regions (28,400 inhabitants) of 3 landscape climatic areas in Guinea: savanna-forest, light and damp tropical forests. The questionnaire was aimed at obtaining quantitative characteristics on important items of population economic activity and number of potential hosts and carriers of natural focus infections in the buildings. Types of the population occupation were differentiated in conformity with various biotopes the people belong to, and according to their direct contacts with domestic, synanthropic and wild animals. The quantity of little mammals (multi-nipple, gray, black and hamster--like rats, mice, shrews, and bats) and ectoparasites (bloodsucking Ixodes, fleas and lice) and intensity of control thereof were estimated according to 4 grades in 6 types of residential and uninhabited constructions.

Zoonotic dermatoses of dogs and cats

Zoonotic dermatoses in dogs and cats are an important cause of skin disease in human beings. In addition, human dermatoses may occasionally be transmitted to dogs and cats. The veterinarian and the physician form a critical "health care team" in the proper management of these disorders.