HEALTH EVALUATION OF A RADIOCOLLARED POPULATION OF FREE-RANGING BAIRD'S TAPIRS (TAPIRUS BAIRDII) IN COSTA RICA

The health of a population of free-ranging tapirs (Tapirus bairdii) inhabiting Corcovado National Park, Costa Rica, was assessed as part of an ongoing ecologic study. Nineteen tapirs were immobilized between March 1997 and February 2000, and samples of blood, skin biopsies, and ectoparasites were collected. Ticks were identified as Amblyomma oblongoguttatum or A. coelebs. Hematology and serum biochemistry results suggest statistically significant differences between free-ranging and captive populations that should be interpreted with caution in view of inherent environmental differences between the two populations. Five of 17 animals tested positive for Leptospira bratislava, and 12 individuals tested positive for Venezuelan equine encephalitis. One of nine skin biopsies examined was abnormal and diagnosed as leukoderma. This report represents the first health assessment of a free-ranging population of tapirs.

Between-group transmission dynamics of the swallow bug, Oeciacus vicarius

The parasitic cimicid swallow bug, Oeciacus vicarius, is the principal invertebrate vector for Buggy Creek virus (BCRV) and has also been associated with Venezuelan equine encephalitis virus. To help understand the spread of this vector, we experimentally measured the transmission of O. vicarius between groups (colonies) of its main host, the cliff swallow (Petrochelidonpyrrhonota), in the field. Transmission of bugs between colonies varied significantly with year, size of the colony, and week within the season. Bug immigration into sites tended to peak in mid-summer. Swallow nests in larger colonies had more consistent rates of bug introduction than did nests in small colonies, but within a colony a given nest's weekly immigrant-bug count varied widely across the season. Transmission of O. vicarius between host social groups follows broadly predictable seasonal patterns, but there is nevertheless temporal and spatial heterogeneity in bug transmission. By understanding how long-distance movement by this vector varies in time and space, we can better predict where and when BCRV epizootics may occur.

Fleas parasitizing domestic dogs in Georgia, USA: Species composition and seasonal abundance

Monthly flea collections were made from domestic dogs in Bulloch County, Georgia, USA from September 1996 to August 2004. A total of 2518 fleas belonging to 8 species were collected. The most common flea was the cat flea, Ctenocephalides felis (389 males and 1148 females), followed by the dog flea, Ctenocephalides canis (250 males and 285 females), a generalist/carnivore flea, Pulex simulans (106 males and 213 females), and a sticktight flea, Echidnophaga gallinacea (3 males and 89 females). Small numbers of rabbit-associated fleas (25 Cediopsylla simplex and 6 Odontopsyllus multispinosus) and rodent-associated fleas (3 Orchopeas howardi and 1 Polygenis gwyni), suggested that certain dogs had acquired these particular ectoparasites through hunting activities. Sex ratios of each of the five most frequently collected flea species were female-biased. Seasonally, C. felis, C. canis, and P. simulans, all showed distinct abundance peaks in late summer or autumn.

Spatial and temporal variations in sea lice (Copepoda: Caligidae) infestations of three salmonid species farmed in net pens in southern Chile

Sea lice infestations have become a major health problem for farmed salmonids throughout the world including Chile. In southern Chile, 6 geographical areas, divided into 22 geographical zones with a total of 127 salmon farming centers and 1519 sea pens, were regularly sampled from December 1999 to April 2002. A linear mixed-effects model (LME) approach was used to describe the infestations of adult forms of sea lice on 3 salmonid species farmed in southern Chile. The variables fish species, water temperature, water salinity, fish weight, juvenile parasite count, pen shape, treatment status in previous month and the interaction of previous and current month treatments were found to be statistically significant fixed effects for the population sampled. The most susceptible species to sea lice infestation was rainbow trout Oncorhynchus mykiss, while the least susceptible species was coho salmon O. kisutch. Fishes in pens treated in the previous month with avermectins were associated with the smallest sea lice count compared to fishes in pens not treated or treated with other products. The variability in sea lice infestations in areas and zones within areas was not statistically significant when controlling for the previously mentioned fixed variables. The variability between centers, the within-pen variability, and the interaction between within-pen effect and the date of measurement were statistically significant and not explained by the fixed effects. Potential sources for this variability are discussed. We conclude that the epidemiology of sea lice infestations in farmed salmonids in southern Chile is complex and in need of further study.

Hesperoctenes fumarius (Hemiptera: Polyctenidae) Infesting Molossus rufus (Chiroptera: Molossidae) in Southeastern Brazil

We analyzed the prevalence, intensity, and medium density of parasitism of Hesperoctenes fumarius infesting Molossus rufus in natural (hollow trees) and anthropogenic roosts (attics) in southeastern Brazil. The prevalence and intensity of infestations were higher in the hollow trees than in the attic roosts. We also noted a relationship between the amount of space available within the roost and the infestation levels of H. fumarius. One advantage of roosting in larger, often man-made, refuges may be the reduction in ectoparasite infestations.

Ectoparasites of the swift fox in northwestern Texas

Ectoparasites were collected from chemically immobilized swift foxes (Vulpes velox) in the Texas Panhandle (USA). Three species of fleas (Pulex irritans, Dactylopsylla percernis, and Euhoplopsyllus affinis) and one species of tick (Ixodes sculptus) were found. Pulex irritans was the only abundant ectoparasite; it occurred on all 23 foxes brushed in 1999-2000 and all but one of 34 hosts examined in 2000-01. Otherwise, this swift fox population had a depauperate ectoparasite fauna; the remainder of the ectoparasites only occurred on a few (< or =5%) of the hosts. Because of previous taxonomic confusion between P. irritans and the closely related P. simulans, the zoogeographic distribution of these two species in many areas of western North America needs to be verified. Apparently, only the human flea P. irritans occurs on wild canids in the Texas Panhandle. However, there are previous records of P. simulans on other carnivores in western and central Texas. Some of these specimens were reexamined, and their identifications were reconfirmed. Also, the recent literature on the controversial taxonomic status of these two flea species is reviewed. The male terminal aedeagal sexual apparatus is the only means currently available to separate P. irritans and P. simulans.

Ectoparasite and hemoparasite infection in a diverse temperate lizard assemblage at Macraes Flat, South Island, New Zealand

A lizard assemblage at Macraes Flat, New Zealand, comprising the common skinks Oligosoma maccanni and Oligosoma nigriplantare polychroma, the endangered species Oligosoma grande and Oligosoma otagense, and the common gecko Hoplodactylus maculatus, was studied to determine the prevalence of ectoparasites and hemoparasites. The mites Odontacarus lygosomae and Ophionyssus scincorum infected all Oligosoma spp. only, and the mite Neotrombicula naultini infected only H. maculatus. The hemoparasite Hepatozoon lygosomarum infected all Oligosoma skinks, except O. n. polychroma. Oligosoma otagense had the highest infection levels of all parasites by several orders of magnitude. For all lizard species, there was no difference in mite prevalence between adult males and adult females, but juveniles were less often infected. For all skink species, there was a significant relationship between presence of the hemoparasite He. lygosomarum and infection intensity of the supposed vector, O. scincorum. It is unclear if patterns of parasite infection reflect species-specific susceptibility, host-parasite species-specific spatial ecology, or environmentally induced host physiological impairment. Considering the threatened nature of O. otagense, evidence of high parasitemia should stimulate further investigation.

Seasonal variation of tungiasis in an endemic community

Tungiasis (caused by the sand flea Tunga penetrans) is hyperendemic in many resource-poor communities in Brazil. To understand transmission dynamics of this parasitic skin disease in a typical endemic area, a longitudinal study was carried out in a slum in Fortaleza in northeastern Brazil. In a door-to-door survey, the population of a randomly selected area (n = 1,460) was examined on four occasions for the presence of embedded sand fleas. Prevalence rates were 33.6% in March (rainy season), 23.8% in June (end of the rainy season), 54.4% in September (peak of the dry season), and 16.8% in January (begin of the rainy season). Tungiasis was more common in males than in females. The intensity of infestation was correlated with the prevalence. The study shows that prevalence of tungiasis and parasite burden vary significantly during the year with a peak in the dry season. These findings have important consequences for the design of control measures.

Parasites of Columba livia (Aves: Columbiformes) in Tenerife (Canary Islands) and their role in the conservation biology of the laurel pigeons

The prevalence and intensity of the parasites from 50 wild doves (Columba livia) from the city of Santa Cruz de Tenerife, in the island of Tenerife (Canary Archipelago), were studied. The following ectoparasites were found in apparently healthy pigeons (prevalences are shown in percentage (%) and mean intensities with their standard deviations): the acari Dermanyssus gallinae (De Geer, 1778) (6, 241.0 +/- 138.9) and Tinaminyssus melloi Fain, 1962 (10%, 218.3 +/- 117.3); the louses, Columbicola columbae Linnaeus, 1758 (100%, 111.4 +/- 76.8) and Campanulotes bidentatus Scopoli, 1763 (94%, 48.4 +/- 26.6); and the pigeon fly, Pseudolynchia canariensis Macquart, 1839 (36%, 6.2 +/- 1.6). The endoparasites we found were: a haemoprotozoan species, Haemoproteus columbae Kruze, 1890 (82%, 14.8 +/- 10.3 per 1000); coccidian oocysts, Eimeria sp. (50%, 0.2 x 10(3) +/- 1.7 x 10(3) per gr); a cestode species Raillietina micracantha (Fuhrmann, 1909) López Neyra, 1947 (44%, 12.3 +/- 9.4); and four nematode species, Tetrameres (Tetrameres) fissispina (Diesing, 1861) Travassos, 1915 (4%, 99.5 +/- 34.1), Synhimantus (Dispharynx) spiralis (Molin, 1858) (8%, 46.8 +/- 11.6), Ascaridia columbae (Gmelin, 1790) Travassos, 1913 (40%, 8.4 +/- 8.8) and Aonchotheca sp. (18%, 6.0 +/- 3.1). Several species detected in our study can be pathogens for C. bollii and C. junoniae, which are endemic pigeons of the Canary Islands, considered endangered species. Parasites (ectoparasites, protozoa and helminths) of C. livia found in Tenerife and others from wild and farm birds in the island were considered as healthy controls.

North Spain (Burgos) wild mammals ectoparasites

Twenty-seven species of arthropods were collected from 105 wild mammals, six wolves Canis lupus (Linnaeus, 1758) included. A total of 87 animals (82.8%) harboured some ectoparasites. Ticks were found in 60% of the samples, fleas in 51.4%, chewing-lice in 3.8%, and others (Mesostigmata and hippoboscids) in 3.8%. Moreover, 42.5% were single infestation and 57.5% mixed. Some of the species were new records for a host in spanish country such as Trichodectes canis (De Géer, 1778), Ixodes trianguliceps (Birula, 1895), Ceratophyllus (Monopsyllus) S. sciurorum (Schrank, 1803) and Paraceras melis melis (Walker, 1856) on several mammals. Two species were new records for Spain: Chaetopsylla matina (Jordan, 1925) and Archaeopsylla erinacei erinacei (Bouché, 1835).

A study of ectoparasites of Canis lupus familiaris in Mueang district, Khon Kaen, Thailand

We studied ectoparasites found on Canis lupus familiaris sampled in five areas in Mueang district, Khon Kaen Province, Thailand. The prevalence of fleas and ticks as well as their density were determined in 100 dogs that did not receive treatments. A total number of 458 ectoparasites was found corresponding to two species: 25.8% Ctenocephalides canis and 74.2% Rhipicephalus sanguineus. R. sanguineus was the most abundant species, and Ct. canis was the only flea species found. The stages of R. sanguineus were larvae (5.3%), nymphs (29.1%) and adults (39.1% in male and 26.5% in female). The stages of Ct. canis were larvae (41.5%) and adults (58.5%). Both species were commonly found on domestic dogs in all areas of the study. Ct. canis was not present on domestic dogs in one sub-district. The prevalence rates of tick-harboring domestic dogs was 80% (R. sanguineus), and flea-haboring domestic dogs was 26% (Ct. canis).

[Seasonal variation of Haematobia irritans in the Santa Catarina State plateau and eficiency of the "Directed Control"]

This experiment had the aims of collecting information about seasonal variation; to evaluate the efficacy of the directed control method, in which only the most susceptible animals to Haematobia irritans infestations are treated and to reduce treatment costs. From February 2001 to April 2003, in two farms situated in Lages, Santa Catarina State, Brazil, two groups of 17 adult animals each (one group per farm) were used to count fly infestation every 14 days. In farm I, 29.4% of the animals were treated with pour-on cypermethrin, at 5 mg/kg live weight, when infestations reached an average above 200 flies (Directed Control). In farm II, treatments were used according to the farmer's decision. Evaluations of the efficacy of treatments were performed 1 to 7 days after treatment. The heaviest infestations occurred from November to April, and the number of flies did not surpassed 115.25 in average. Animals in farm I were treated only once, in December 2001, and a reduction of the infestation of H. irritans of 89.35% was showed. The 29.4% of most susceptible animals, in the time of heaviest infestations, sustained 65.97% of the total population of H. irritans. In farm II, animals were treated 9 times, and the efficacy of the treatments reached 98.25%. It was found that in this farm an excessive number of treatments have been used for the control of H. irritans.

Ectoparasitism and vector-borne diseases in 930 homeless people from Marseilles

Homeless people are particularly exposed to ectoparasites, but their exposure to arthropod-borne diseases has not been evaluated systematically. A medical team of 27 persons (7 nurses, 6 infectious disease residents or fellows, 2 dermatologists, and 12 infectious disease specialists) visited the 2 shelters in Marseilles, France, for 4 consecutive years. Homeless volunteers were interviewed, examined, and received care; and blood was sampled for cell counts and detection of bacteremia, antibodies to louse-borne (Rickettsia prowazekii, Bartonella quintana, and Borrelia recurrentis), flea-borne (R. typhi, R. felis), mite-borne (R. akari), and tick-borne (R. conorii) bacterial agents. We selected sex- and age-adjusted controls among healthy blood donors. Over 4 years, 930 homeless people were enrolled. Lice were found in 22% and were associated with hypereosinophilia (odds ratio, 5.7; 95% confidence intervals, 1.46-22.15). Twenty-seven patients (3%) with scabies were treated with ivermectin. Bartonella quintana was isolated from blood culture in 50 patients (5.3%), 36 of whom were treated effectively. The number of bacteremic patient increased from 3.4% to 8.4% (p = 0.02) over the 4 years of the study. We detected a higher seroprevalence to Borrelia recurrentis, R. conorii, and R. prowazekii antibodies in the homeless. Our study shows a high prevalence of louse-borne infections in the homeless and a high degree of exposure to tick-borne diseases and scabies. Despite effective treatment for Bartonella quintana bacteremia and the efforts made to delouse this population, Bartonella quintana remains endemic, and we found hallmarks of epidemic typhus and relapsing fever. The uncontrolled louse infestation of this population should alert the community to the possibility of severe re-emerging louse-borne infections.

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.

Gill histopathology of wild marine fish in Tasmania: potential interactions with gill health of cultured Atlantic salmon, Salmo salar L

This study surveyed conditions in the gills of wild marine fish in Tasmania to determine potential interactions between wild and cultured fish. Wild marine fish of 12 species were captured from three Atlantic salmon farm sites and three reference sites around Tasmania. The survey concentrated on three species, red cod, Pseudophycis bachus, sand flathead, Platycephalus bassensis, and jack mackerel, Trachurus declivus. Seventy-six per cent of salmon pens contained wild fish species. The number of species found in a pen ranged from one to nine and the number of individuals ranged from one to 23. Trichodinids were prevalent and occurred on seven of the 13 species examined. Trichodina occurred on the gills of all but one specimen of red cod. Monogenean gill flukes were observed on all three major species sampled and were abundant on sand flathead. Other parasites and conditions observed in the survey included metacercariae of digenean trematodes, epitheliocystis and cysts of unknown origin. Infestations of trichodinids on red cod and monogenean gill flukes on sand flathead were significantly more intense at farm sites than at reference sites. Atlantic salmon sampled at the same time from the farms were only affected by amoebic gill disease and isopods.

The animal reservoir of Tunga penetrans in severely affected communities of north-east Brazil

Tungiasis is a zoonotic ectoparasitosis caused by the sand flea Tunga penetrans L. (Siphonaptera: Tungidae). This disease is hyperendemic in poor communities of north-east Brazil, causing considerable morbidity in affected human populations, but the animal reservoirs have not been investigated previously in Brazil. To assess the prevalence and intensity of T. penetrans infection in domestic and peri-domestic animals, as well as in the human population, we surveyed two typical communities of north-east Brazil: an urban slum and a traditional fishing village. In the slum we examined 849 humans, 121 cats, 82 dogs, 2 pigs, 2 rabbits, 1 monkey and 56 rodents, comprising 34 rats (Rattus rattus L.) and 22 mice (Mus domesticus L). In the fishing village we examined 505 humans, 68 dogs, 37 cats, 7 donkeys, 4 cattle, 3 pigs and 1 monkey. Tungiasis was common among dogs and cats of both communities, with respective prevalence rates of 67.1% (95% CI: 55.8-77.1) and 30.9% (95% CI: 20.2-43.3) in dogs, 49.6% (95% CI: 40.4-58.8) and 32.4% (95% CI: 18.0-49.8) in cats. Slum rats were 41.2% (95% CI: 24.6-59.3) infested, but the other animals were not. Human prevalence rates were 54.4% (95% CI: 51.0-57.8) in the slum and 52.1% (95% CI: 47.6-56.5) in the fishing village. High prevalence rates (range 31-67%) of tungiasis in humans, pets and rats (but apparently not other animals) indicate the need for an eco-epidemiological approach to control of this anthropo-zoonotic problem.

Outbreak investigation of scrub Typhus in Himachal Pradesh (India)

Scrub Typhus outbreak investigation was undertaken during September 2003 in the three worst affected districts Shimla, Solan and Sirmaur in Himachal Pradesh (India). A total of 113 cases and 19 deaths (17.27 percent case fatality rate) were reported from the eight districts, which were reporting cases. Cases were prevalent in all age groups and in both the sexes among the persons frequenting forest for occupational work. 35.7 percent of the patients serum samples showed a titer of > 1: 80 against OX 19 and OXK antigen is suggestive of Scrub Typhus. Entomologically Rattus rattus (39.5 per cent) was the most prevalent species followed by Suncus murinus (22.91 percent), Bandicoota bengalensis (29.16 percent) and Bandicoota indica and Mus musculus (4.16 percent each). Vector species Leptotrombidium deliense and Gahrliepia (schoengastilla) sp. were recorded. The chigger index 23.0 was found to be highest in Vill. Baldian and 5.0 in Vill. Bhatakuffer (Shimla) and 1.0 in Vill. Rebon (Solan), which is above the critical limit of 0.69 per rodents. Other mite species, ixodid ticks, fleas and lice have been recorded.

Parasites of domestic and wild animals in South Africa. XLIV. Fleas (Insecta : Siphonaptera : Pulicidae) collected from 15 carnivore species

Fleas were collected from 61 wild carnivores belonging to 13 species in various nature reserves and on farms, two feral domestic cats in a nature reserve and a domestic dog in the city of Johannesburg. Eleven flea species, including two subspecies of one of these, belonging to six genera were recovered. Amongst these only Ctenocephalides felis felis and Ctenocephalides felis strongylus are considered specific parasites of carnivores. The remaining ten species normally infest the prey animals of the various carnivores.

Investigations on the biology, epidemiology, pathology and control of Tunga penetrans in Brazil. V. Cytokine concentrations in experimentally infected Wistar rats

Tungiasis is caused by the penetration of the female sand flea Tunga penetrans into the skin of its host. This parasitic skin disease is almost invariably associated with an intense inflammation around embedded fleas, the underlying mechanisms being unknown. A study was undertaken to determine whether Wistar rats can be used as an animal model to assess cytokine kinetics during the natural course of the infection. Laboratory-raised Wistar rats were exposed in cages put on the soil in an area with high human attack rates. Rats were examined daily and blood samples were taken before exposure and at 2, 6, 10, 13, 16 and 20 days after flea penetration. TNF-alpha, IL-1 beta, IFN-gamma, IL-4, IL-10 and CINC (a rat cytokine- induced neutrophil chemoattractant and member of the IL-8 family) were determined by enzyme immunoassay. The results showed an increasing serum concentration of TNF-alpha and IL-1 beta 10-13 days after penetration and a rapid increase in IL-4 2 days after fleas became embedded. During the natural course of the infection, the ratio of the serum concentration of TNF-alpha to that of IL-10 decreased, indicating a relative increase in the secretion of the anti-inflammatory cytokine. The treatment of lesions with silicone oil abrogated the natural disease course and changed the pattern of cytokine secretion. We conclude that the Wistar rat is an appropriate model to study immune responses in tungiasis.

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%.

Immune responses to fleas in two rodent species differing in natural prevalence of infestation and diversity of flea assemblages

We studied in vivo immune response to fleas in two gerbils, Gerbillus dasyurus and Gerbillus andersoni allenbyi, which differed in their natural species richness of flea assemblages and prevalence of infestation. G.dasyurus is parasitized naturally by several flea species, but the prevalence of infestation is low, whereas G. a. allenbyi is parasitized by a single flea species, with high prevalence of infestation. We hypothesized that immunological parameters and the cell-mediated specific immune response to an antigen from an unfamiliar flea species differ between the two gerbil species. Parasitized and control gerbils of both species demonstrated similar, relatively low levels of spontaneous glucose consumption. The same was true for the phytohemagglutinin treatment. Responses to antigen from unfamiliar flea species were higher than both spontaneous glucose consumption and response to phytohemagglutinin in parasitized and control G. a. allenbyi and parasitized G. dasyurus. However, no significant difference in the spontaneous blast transformation index and responses to both phytohemagglutinin and flea antigen was found in control G. dasyurus. The number of white blood cells was significantly lower in control than in parasitized G. dasyurus, whereas no difference in the number of white blood cells was found between control and parasitized G. a. allenbyi. The levels of circulating immune complexes and concentrations of immunoglobulins did not differ between parasitized and control individuals in both species. Phagocytic activity was significantly higher in males than in females of G. a. allenbyi but not of G. dasyurus. In addition, phagocytes of G. dasyurus appeared to be significantly more active than those of G. a. allenbyi.

Investigations on the biology, epidemiology, pathology and control of Tunga penetrans in Brazil: IV. Clinical and histopathology

Tungiasis is a parasitic skin disease caused by the sand flea Tunga penetrans. This ectoparasitosis is endemic in South America, the Caribbean and sub-Saharan Africa, where it is an important but neglected health problem in resource-poor communities. As part of a study of tungiasis-related morbidity in a typical slum in Fortaleza, Brazil, we identified 86 individuals with tungiasis. Lesions were counted, classified according to the stage of development, and clinical pathology was documented. One hundred and nine lesions were biopsied and examined by histological sectioning. The patients had between 1 and 145 lesions (median 14.5), the majority occurring in clusters. In all, 77% of patients reported severe pain at the site of the lesion, and 52% had one or more nails lost or severely deformed. Intense inflammation and/or fissures hindered 45% of the patients from walking normally. Signs of superinfection were observed in 29%, and signs of generalized inflammation in 2% of patients. Clinical pathology was significantly related to the number of lesions, and the total number of parasites present correlated with the number of fleas occurring in clusters. Clinical pathology was frequently accompanied by a pathological alteration of the epidermis (predominantly hyperplasia, parakeratosis, hyperkeratosis, and spongiosis) and the dermis. Tungiasis causes a broad spectrum of clinical histopathological alterations, and is a serious health threat in a typical, impoverished community in northeast Brazil. The clinical pathology is closely related to the parasite burden of an individual and the clustering of embedded fleas at certain predilection sites.

Variation in the load of the horn fly, Haematobia irritans, in cattle herds is determined by the presence or absence of individual heifers

The distribution of horn flies, Haematobia irritans (L.) (Diptera: Muscidae), in herds of Danish Holstein-Friesian cattle was investigated in two studies conducted during two field seasons. In the first study, highly significant differences in fly distribution between the most and the least fly-susceptible heifers were observed. In one herd, the mean difference between the most fly-susceptible and the most fly-resistant heifers was 268 Ha. irritans specimens. The highest ratio between upper and lower mean fly number was 64.1:1, whereas the lowest was 3.1:1. In the second year, it was demonstrated that the heifers kept their rank in fly attraction over time. The trial clearly demonstrated that some heifers were attracting flies, whereas others, even in the same herd, only carried a few. In the second study, heifers were moved in and out of herds in an attempt to manipulate fly loads in the herds. In year 1, one herd (herd A) received four fly-resistant heifers from another herd (herd B), resulting in a drop in the mean number of flies, whereas herd B received four fly-susceptible heifers from herd A, resulting in an elevation of the mean number of flies. In year 2, a similar pattern emerged using herds C and D, and when the cattle were later returned to their original herds, the fly loads returned to their original distribution. The data presented here show unequivocally that, for horn flies, there can be considerable differences in fly loads for individual heifers within the Holstein-Friesian breed. Furthermore, the overall fly load within herds can be manipulated, and can be reversed. Thus, the distribution in the number of flies within a herd appears to depend on the number of fly-resistant or fly-susceptible heifers. The possible role of chemical factors emitted by heifers, i.e. volatile semiochemicals, in determining differences in fly loads is discussed, whereby attractants are emitted by fly-susceptible heifers and enable flies to locate their host, and repellents are emitted by fly-resistant heifers such that the flies are actively repelled from the herd.

Pathogen carriage by the cat flea Ctenocephalides felis (Bouché) in the United Kingdom

The carriage of Bartonella, Rickettsia felis and haemoplasma species was investigated in cat fleas (Ctenocephalides felis) collected from 121 cats and dogs in the United Kingdom. DNA extracted from fleas was analysed using genus and species-specific PCR and amplicons were characterised using DNA sequencing. Fifty percent of flea samples were PCR positive for at least one pathogen. Twenty one percent were positive for R. felis, 17% for Bartonella henselae, 40% for haemoplasma species and 20% were infected with more than one of the pathogen species studied. It is clear from the results in this study that companion cats and dogs are commonly infested with Ct. felis carrying bacterial pathogens of significance to human and animal health. These findings raise the possibility that Ct. felis found on dogs and cats are a potential source of infection with such pathogens for humans.

Long-term epidemiology, effect on body condition and interspecific interactions of concomitant infection by nasopharyngeal bot fly larvae (Cephenemyia auribarbisandPharyngomyia picta, Oestridae) in a population of Iberian red deer (Cervus elaphus hispanicus)

We studied the pattern of infection and the inter-annual variation and individual factors affecting the infection of 2 species of nasopharyngeal bot flies,Cephenemyia auribarbisandPharyngomyia picta(Diptera: Oestridae), in a population of Iberian red deer (Cervus elaphus hispanicus) from south central Spain (10 annual periods between 1990 and 2003). Mean prevalence±S.E.95%CIof infection was 35·19±4·24% (n=486). The frequency distribution of the parasites was markedly aggregated (K: 0·213, mean abundance±S.D.: 5·49±12·12). Parasite load of Oestridae peaked at calf and subadult age groups and declined thereafter, which suggests that acquired immunity may be acting. In common with other host–parasite relationships, male hosts were found to have higher prevalence and abundance levels than females. The prevalence ofP. pictawas positively affected by the presence ofC. auribarbiswhereas the intensity of infection ofP. pictawas negatively affected by the presence ofC. auribarbis. Intensity ofP. pictain concomitant infections withC. auribarbiswas lower than in pureP. pictainfections, whilst the intensity ofC. auribarbisinfections did not change. This provides good evidence of interspecific competence, which could be dealt with by parasites by means of asynchronous life-cycles and different maturation periods. Weather also affects the dynamics and transmission rates of these parasites. Previous annual rainfalls positively affected the level of infection with oestrids. Yearly autumn rainfalls affected positivelyP. picta, possibly due to an effect on the pupal stage survival. Infection of Oestridae affected body condition in calves and subadults, suggesting that oestrids could have sublethal effects on Iberian red deer. Future research is needed to investigate the effect of parasites on the dynamics of the Iberian red deer.