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PubMed1995

Chronic lyme disease in the rhesus monkey.

BACKGROUND: We have previously reported the clinical, pathologic, and immunologic features of "early" Borrelia burgdorferi infection in rhesus monkeys (3). We have now evaluated these features during the chronic phase of Lyme disease in this animal model. EXPERIMENTAL DESIGN: Clinical signs, and pathologic changes at the gross and microscopic levels, were investigated 6 months post-infection in several organ systems of five rhesus macaques (Macaca mulatta), which were infected with Borrelia burgdorferi by allowing infected Ixodes scapularis nymphal ticks to feed on them. A sixth animal was used as an uninfected control. Borrelia antigens recognized by serum antibody were identified longitudinally by Western blot analysis, and C1q-binding immune complexes were quantified. Localization of the spirochete in the tissues was achieved by immunohistochemistry and in vitro culture. The species of spirocheta cultured was confirmed by the polymerase chain reaction. RESULTS: Chronic arthritis was observed in five out of five animals. The knee and elbow joints were the most consistently affected. Articular cartilage necrosis and/or degenerative arthropathy were the most severe joint structural changes. Synovial cell hyperplasia and a mononuclear/lymphocyte infiltrate were commonly seen. Nerve lesions were also observed, including nerve sheath fibrosis and focal demyelinization of the spinal cord. Peripheral neuropathy was observed in five out of five animals and could be correlated in the most severely affected monkey with the presence of higher levels of circulating immune complexes. Differences in disease severity did not correlate with differences in the antigens recognized on Western blot analysis. CONCLUSIONS: B. burgdorferi infection in rhesus macaques mirrors several aspects of both the early and chronic phases of the disease in humans. This animal model will facilitate the study of the pathogenesis of Lyme arthritis and neuroborreliosis.

Animals↗
PubMed1997

[Unauthorized vaccines put on the market are useful for certain travelers].

Certain vaccines such as the amaril vaccine are highly recommended and even required from the traveller. Other vaccinations concern persons travelling in regions where they might be infected by pathogens not present in their countries of origin. There exist vaccines which are available in certain countries but which are not (or not yet) allowed on the French market. This is the case for the Japanese encephalitis (JE) and for the tick encephalitis (TE) of Central Europe. Details should be given about how the traveller can benefit from these vaccines, and about practical procedures to obtain them. The agents responsible are viruses transmitted by arthropods (the mosquito and the tick, respectively). The variability of the risk and the seasons of transmission, variable from one region to another (especially as far as JE is concerned), have to be taken into account. Also, the small risk of infection presently encountered and the small percentage of persons developing clinical syndromes after an infectious bite should be taken into consideration. Practically speaking, vaccination against the Japanese encephalitis is recommended to those persons who plan to stay in an endemic or epidemic region for several weeks during the season of transmission, especially if a trip into rural areas is entailed. As far as tick encephalitis is concerned, infection can take place in all rural areas (meadows, clearings, underwoods ...) of the Vosges and the zones east of them, especially in Central Europe, Russia and Siberia. While the decision is still justifiably pending as to whether to allow these vaccines on the market, it is possible to obtain from the public health administration a temporary authorization for their administration. Travellers should in any case be strongly advised to protect themselves against the bites of arthropods.

Drug and Narcotic Control↗
PubMed1988

A climate-based model for the development of the ixodid tick, Rhipicephalus appendiculatus in East Coast fever zones.

East Coast fever (Theileria parva infection) is an important parasitic disease of cattle in East and Central Africa. Past experimental studies have provided a great deal of information on the dynamics of the life cycle of the tick vector, Rhipicephalus appendiculatus. This paper describes a mathematical model based on field observations to explain the close relationship between the tick life cycle and climate. The model provides a basis for the future study of different ECF control programmes using computer experiments.

Africa, Eastern↗
PubMed2005

Cellular infiltration at skin lesions and draining lymph nodes of sheep infested with adult Hyalomma anatolicum anatolicum ticks.

Immunohistochemical analysis of skin and draining lymph nodes of sheep repeatedly infested with the ixodid tick Hyalomma anatolicum anatolicum were studied for different antigen-presenting cells and lymphocyte subpopulations. Infiltration of neutrophils, macrophages and lymphocytes adjacent to the tick bite site were observed. Skin biopsies showed significant increases in dermal infiltration of CD8+ and gammadelta+ T cells at 72 h and 8 days after both primary and secondary infestation. Infiltrations of MHC-II DR/DQ decreased at 72 h after tick infestation, whereas significant increases were recorded for 8-day skin biopsies. CD1+ cellular infiltrations were observed during secondary infestations at the dermis. Decreased ratios of CD4:CD8 T cells and MHC-II:CD1 antigen-presenting cells were observed in both infestations compared to healthy skin biopsies. Ratios of alphabeta:gammadelta T cells increased gradually during infestation compared to uninfested skin. The regional lymph nodes from tick-infested sheep showed an increased CD8+, gammadelta+ T and CD1+ cellular infiltration compared to control lymph nodes. CD4+ T cells were decreased. There were no significant changes in CD45R+ cellular infiltration either at skin lesions or regional lymph nodes.

Animals↗
PubMed1975

Cryopreservation of infective larvae of Dipetalonema viteae.

infective larvae of Dipetalonema viteae produced infections in Mongolian jirds (Meriones unguiculatus) after storage of infected ticks (Ornithodoros tartakovskyi) in the presence of dimethyl sulfoxide (DMSO, 5%) for 7 or 595 days in liquid nitrogen (-196 C). Infectivity of these larvae was only partially impaired. Microfilaremias of test jirds were generally lower than those of control jirds given nonfrozen larvae; however, the majority of test jirds developed microfilarial counts suitable for use in infecting ticks. In contradistinction, larvae frozen free of the tick failed to retain infectivity. Apparently the tick, in conjunction with DMSO, protects the larvae during freezing and thawing.

Animals↗
PubMed1989

[Dermatophilus congolensis bovine dermatophilosis in the French West Indies. III. A comparison between infected and non-infected cattle].

The determination of the distinctive features between infected and uninfected cattle by Dermatophilus has been performed among 93 bovine stock in La Martinique, and 120 in La Guadeloupe and Saint-Martin Islands. Nearly half of the herds had been or were infected. Morbidity rates reach 33 per cent in La Martinique and 29 per cent in La Guadeloupe with a mortality ratio of 15 per cent and 5 per cent respectively. No frequency difference could be observed with respect to the season or the geographical area. Similarly, differences are little or nil as regards animal exposure toward aggressive factors such as sun, soil moisture, thorns, etc. On the other hand, the presence of Amblyomma variegatum is a determining factor considering the prevailing situation in La Martinique, where all breeds of cattle are sensitive to the disease. In this case, 63 per cent of the tick infested cattle develops dermatophilosis versus 2.5 per cent for the still uninfected animals. Conversely, in La Guadeloupe were Creole zebus are highly resistant (as a consequence of their natural selection), only 27 per cent of the infected stock suffers from this illness. In these two islands, regular dipping measures have proved to be beneficial in that it reduces the disease frequency. The study also reveals an underlying typology of the various rearing systems, thus allowing their classification as for their behaviour and response when meeting illness. In La Martinique, whatever they may be, quite none of them is infected in the tick free area. In the tick infested zones, the traditional small breeders rearing a sensitive cattle and who do not care with prophylactic rules, are mostly stricken, while more structured ones have succeeded in controlling the disease, owning to some appropriate measures together with a fair animal management. On the other hand, in La Guadeloupe where this tick is cosmopolitan, the small breeders who run a resistant Creole cattle, are not concerned, despite a rudimentary prophylactic behaviour. Conversely, the intensive rearing system, based upon improved imported breeds, meets great difficulties to master the infection.

Actinomycetales Infections↗
PubMed1987

Arthropod parasites of some wild animals in South Africa and Namibia.

Earlier research on the parasites of wild animals in South Africa is reviewed and the findings of more recent research discussed. The life cycles of various gasterophilid and oestrid fly species are described and the seasonal abundance of their larvae in their zebra and antelope hosts is considered. The seasonal abundance of fleas, lice and ixodid ticks on their hosts is given and the role played by both small and large mammals and some birds in the maintenance of tick populations is described. Factors contributing to severe parasitism of wild animals are listed and the chemical and biological control of ectoparasites of wild animals are discussed.

Animals↗
PubMed1994

Immunization of mice by recombinant OspA preparations and protection against Borrelia burgdorferi infection induced by Ixodes ricinus tick bites.

The wide distribution of Borrelia burgdorferi, the spirochete causing Lyme borreliosis, represents a human health hazard in many areas of the world. Vaccination has been proposed as an effective prevention strategy. Vaccination experiments were conducted with preparations of recombinant outer surface protein A (OspA) derived from Borrelia burgdorferi strain ZS7. Mice received three doses (1 microgram each) of the antigens adsorbed to aluminum hydroxide. A strong immune response to the vaccine antigen was observed. Mice were challenged after immunization, using Ixodes ricinus nymphal ticks infected with Borrelia burgdorferi strain ZS7. Infection was investigated by ear biopsy culture, xenodiagnosis with uninfected larvae and serological response to Borrelia burgdorferi antigens. All unimmunized control animals were found to be infected, while all immunized animals were found to be protected against infection by Borrelia burgdorferi. In addition, most adult ticks derived from nymphs that fed on immunized mice were found to be free of spirochetes.

Animals↗
PubMed1999

The pigeon tick (Argas reflexus): its biology, ecology, and epidemiological aspects.

The European pigeon tick, Argas reflexus (F.), is in central Europe predominantly an urban pest parasitizing wild and domesticated pigeons, Columba livia. Under certain circumstances, however, it also bites humans, occasionally causing an IgE-mediated type-I allergy. Control of A. reflexus is very difficult because of a number of remarkable morphological, physiological, and behavioural features of the tick. The present study aimed at elucidating the distribution and the frequency of occurrence of A. reflexus in Berlin and its possible vector role for Borrelia burgdorferi sensu lato (s. l.). Buildings reported by occupiers to be infested with A. reflexus were personally examined. In addition, the carrier status of this soft tick for B. burgdorferi (s. l.) was investigated in three German towns by an indirect immunofluorescence assay. A total of 188 Berlin buildings was found to be infested with A. reflexus between 1989 and 1998. Infestations were found in 17 out of the 21 districts, clustering in the inner city. There was only a single Borrelia-positive tick out of 800 sampled in Berlin, Leipzig, and Hannover using the genus specific antibody H9724. The same tick was PCR-negative for B. burgdorferi outer surface protein A. Neither these results nor those of other studies on the occurrence of antibodies against B. burgdorferi in pigeons suggest that field populations of A. reflexus and/or pigeons in central Europe harbour the causative agent of Lyme borreliosis.

Animals↗
PubMed1994

The interactions of the flavivirus envelope proteins: implications for virus entry and release.

Viral membrane proteins play an important role in the assembly and disassembly of enveloped viruses. Oligomerization and proteolytic cleavage events are involved in controlling the functions of these proteins during virus entry and release. Using tick-borne encephalitis virus as a model we have studied the role of the flavivirus envelope proteins E and prM/M in these processes. Experiments with acidotropic agents provide evidence that the virus is taken up by receptor-mediated endocytosis and that the acidic pH in endosomes plays an important role for virus entry. The envelope glycoprotein E undergoes irreversible conformational changes at acidic pH, as indicated by the loss of several monoclonal antibody-defined epitopes, which coincide with the viral fusion activity in vitro. Sedimentation analysis reveals that these conformational changes lead to aggregation of virus particles, apparently by the exposure of hydrophobic sequence elements. None of these features are exhibited by immature virions containing E and prM rather than E and M. Detergent solubilization, sedimentation, and crosslinking experiments provide evidence that prM forms a complex with protein E which prevents the conformational changes necessary for fusion activity. The functional role of prM before its endoproteolytic cleavage by a cellular protease thus seems to be the protection of protein E from acid-inactivation during its passage through acidic trans Golgi vesicles in the course of virus release.

Acids↗
PubMed1986

Development and mortality of Ornithodoros moubata after feeding through an artificial membrane.

High mortality rates have often been observed when artificial feeding techniques are used for colony maintenance of Ornithodoros moubata. Such fatalities can be readily controlled by addition of antibiotics to the feeding medium without apparent toxicity to ticks. Comparative results show that for maintaining colonies of O. moubata artificial feeding techniques can be as efficient as direct feeding on swine--the primary hosts of these argasids.

Animals↗
PubMed1992

Lyme disease.

Lyme disease, a multisystem disorder, has now been reported to the Centers for Disease Control from 43 states of the United States. The disease is a tick-transmitted infectious disorder caused by the spirochete bacterium Borrelia burgdorferi. Lyme disease typically begins with the symptoms of flu associated with a characteristic skin rash, erythema chronicum migrans. The diagnosis of Lyme disease is best made by clinical examination and epidemiologic history, with serologic studies supporting the clinical diagnosis. Prompt diagnosis and early treatment with antibiotics will often lead to the resolution of symptoms and the prevention of late complications, Lyme carditis, neurologic manifestations, and arthritis.

Anti-Bacterial Agents↗
PubMed1997

Pathogenicity of the entomopathogenic fungus Metarhizium anisopliae (Deuteromycetes) to Ixodes scapularis (Acari: Ixodidae).

The entomopathogenic fungus Metarhizium anisopliae is highly pathogenic to the black-legged tick, Ixodes scapularis. Spore concentrations of 10(8)/ml for engorged larvae and 10(7)/ml for engorged females resulted in 100% tick mortality, 2 wk postinfection. The LC50 value for engorged larvae (concentration to kill 50% of ticks) was 10(7) spores/ml. Metarhizium anisopliae shows considerable potential as a microbial control agent for the management of Ixodes scapularis.

Animals↗
PubMed1979

Some aspects of the epidemiology and control of bovine babesiosis in Australia.

A short account of the epidemiology and control of babesiosis in Australia is presented. Epidemiological topics discussed include differences in the transmission of Babesia bovis and B. bigemina by the cattle tick, Boophilus microplus and the relative prevalence, disease incidence and pathogenicity of B. bovis and B. bigemina. Circumstances under which babesiosis occurs in Australia are described. In the Section on control, only vaccination is discussed. Changes in the preparation of babesial vaccines, particularly those resulting in a highly infective vaccine containing relatively avirulent B. bovis are described. Fluctuations in demand, such as the increase from about 100,000 to over 1,000,000 doses in 4 years in the mid-1960s are shown. An unexpected increase in the use of A. centrale in 1973 is discussed, and the supply of B. bigemina for cattle exported from Australia reported.

Animals↗
PubMed1988

Efficacy of topically applied ivermectin against Boophilus microplus (Canestrini, 1887) in cattle.

Systemic efficacy of ivermectin applied topically was evaluated against the cattle tick, Boophilus microplus. Twenty cattle with induced infestations were randomly allocated to five groups of equal size based on the numbers of engorged female ticks which fell through the slatted floor of individual pens during the 3 days prior to treatments. Control cattle were non-medicated. Cattle in three groups were given ivermectin at 200, 500 or 1000 mcg kg-1 in a topical formulation applied along the backline from the withers to the rump; cattle in the fifth group were given ivermectin in an injectable formulation subcutaneously at 200 mcg kg-1. Individual 24-h tick collections were made three times weekly for 5 weeks after treatment. Engorged female B. microplus were incubated to determine effects on reproduction. Based on the numbers of engorged female B. microplus collected following treatments, overall efficacy of ivermectin applied topically at 200, 500 and 1000 mcg kg-1 was 50, 85 and 91%, respectively, whereas ivermectin given at 200 mcg kg-1 subcutaneously was 80% effective. The index of reproduction for ivermectin given topically was reduced by 84, 94 and 95%, respectively, and that for ivermectin subcutaneously was 94%. No significant differences (P greater than 0.05) were found for these variables between ivermectin given topically at 500 or 1000 mcg kg-1 versus 200 mcg kg-1 given subcutaneously.

Administration, Topical↗
PubMed1985

Treatment of Theileria annulata infection in calves with parvaquone.

Fifteen calves were infected by the injection of stabilate of a suspension of Hyalomma anatolicum anatolicum ticks infected with the Ankara strain of Theileria annulata. Three were kept untreated, as controls, and they all died of theileriosis. Three groups of four calves were treated intramuscularly with parvaquone (Clexon; Wellcome) when early signs of theileriosis were clinically apparent. One group received 20 mg (kg bodyweight)-1 of parvaquone 10 days after infection. Two of these calves were clinically cured and two died of theileriosis. The remaining two groups of four calves received two doses of parvaquone, each of 10 mg (kg bodyweight)-1, either on days 10 and 11 or days 10 and 12. Three calves in each group were clinically cured while one in each group died of theileriosis. Total parasitological cure was not achieved in any of the calves. No symptoms of toxicity due to parvaquone treatment were observed.

Animals↗
PubMed1999

Diagnostic value of dengue virus-specific IgA and IgM serum antibody detection.

The diagnostic value of dengue virus (DV)-specific immunoglobulin A (IgA) serum antibody detection, by an indirect immunofluorescence assay (IFA) was evaluated. For this study, the kinetics of DV-specific IgA serum antibodies was analysed in two experimentally immunised macaques, paired samples from 35 patients suspected of a primary or secondary DV infection, paired sera from patients with high levels of IgA specific antibodies against influenza virus (n = 15), sera from patients with other viral infections (n = 40) and healthy blood donors (n = 10), which served as controls. The presence of DV-specific IgA serum antibodies in humans and in monkeys was compared with that of DV-specific IgM demonstrated in a capture enzyme-linked immunosorbent assay (ELISA). The development of DV-specific IgA and IgM antibodies in macaques proved to be similar to that observed in humans with a DV infection. In sera obtained from suspected primary DV patients during the acute phase and convalescent phase, DV-specific IgA was detected in 1/6 (17%) and 6/6 (100%), whereas IgM was detected in 4/6 (67%) and 5/6 (83%), respectively. In sera from suspected secondary DV patients during the acute phase and convalescent phase, DV-specific IgA was detected in 18/29 (62%) and 28/29 (97%), whereas IgM was detected in 20/29 (69%) and 28/29 (97%), respectively. The control group consisted of five paired serum samples from yellow fever vaccinated individuals and a patient with acute tick-borne encephalitis, 15 paired serum samples from patients with high levels of IgA antibodies specific for influenza virus and 40 serum samples from patients with specific IgM antibodies against other viruses. Ten serum samples from healthy blood donors were included. Among the control serum samples, in one patient, both DV-specific IgA and IgM antibodies were present, and in three sera DV-specific IgM antibodies could be demonstrated. These data suggest that detection of DV-specific IgA serum antibodies by IFA may have additional value for the diagnosis of DV infection.

Animals↗
PubMed2001

Influence of acaricide resistance on cattle-fever tick (Boophilus spp.) infestations in semi-arid thornshrublands: a simulation approach.

Cattle-fever tick (Boophilus microplus and B. annulatus) populations that develop acaricide resistance become more difficult to control or eradicate. We used a simulation model to assess the direct and indirect effects of interactions among season, habitat type, grazing strategy, and acaricide resistance on the ability to eradicate Boophilus infestations in semi-arid thornshrublands of Texas, USA. Season of infestation appeared to have the strongest effect, with infestations begun on 27 September (autumn) tending to die out sooner than those begun on 1 March (spring) and to remain undetected. Habitat type had the next strongest effect, with infestations surviving much longer as canopy cover increased from uncanopied buffelgrass (Cenchrus ciliaris) habitats to mesquite (Prosopis glandulosa)-canopied grass habitats. Acaricide resistance had a moderate effect; as expected, highly resistant tick populations survived longer than those with no acaricide resistance. The importance of grazing strategy varied with changes in habitat type: as canopy cover increased, infestation duration increased faster under continuous grazing than under rotational grazing strategies. Importance of grazing strategy also varied with acaricide resistance: detected tick populations with no and slight acaricide resistance subjected to acaricide treatments tended to survive longer under rotational grazing than continuous grazing, due to reduced contact with a treated host. Populations with moderate and high resistance behaved more like untreated populations, tending to survive longer under continuous, rather than rotational, grazing, because they experienced less mortality on a treated host. Assuming acaricide treatments at 2-week intervals and maintenance of cattle in infested pastures, results indicate that, for each habitat type, infesting ticks have a threshold of acaricide resistance below which one can eradicate them faster with continuous grazing than with rotational grazing. As canopy cover increases, this threshold appears to shift from high resistance (in grass) to slight resistance (in mesquite).

Animals↗