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Multicentric study of seroprevalence of Borrelia burgdorferi and Anaplasma phagocytophila in high-risk groups in regions of central and southern Italy.

The aim of this study was to evaluate the seroprevalence of B. burgdorferi and A. phagocytophila in populations of workers from 4 Italian regions, known to be exposed to tick bites. A total of 712 serum samples collected were divided as follows: 387 samples were obtained from workers at risk for tick bites and 325 from individuals that were not considered to be at risk of ticks bites and served as the control group. Antibodies against B. burgdorferi were found in 29 (7.5%) of the 387 risk workers and in 4 (1.2%) of the 325 control group. Antibodies reactive with the HGE agent were found in 22 (5.7%) of the 387 risk workers and in 3 (0.9%) of the 325 control group. Antibodies to both B. burgdorferi and A. phagocytophila were found in 1.6% of the forestry workers confirming the possibility of coinfection or concurrent infection. The present finding show significant differences between seroprevalence of the risk workers and that of the people with no risk for tick exposure.

Anaplasma phagocytophilum↗

[Plant smells---important determinants in the behavior and rate of development of ixodid disease vectors].

Experiments with nymphs of Ixodes persulcatus and Dermacentor marginatus have shown that the rate and degree of engorgement, dropping off from the mouse, metamorphosis longevity and weight of emerging imagoes change under plant odour influence. The influence of acetone extract vapours of pepper, poplar buds, linden and aspen was tested. Under the influence of the vapour, acting as an attractant for the adults, engorgement weight of their nymphs and the weight of imagoes emerging from them increased; attractants change the nymph-imago metamorphosis duration as well. Repellent acting odours, as a rule, produce an opposite reaction. The phenomenon of the inversion of the infected D. marginatus reaction to the odour is proved in nymphs. Attractant for naive adult ticks (poplar buds) increased the time of feeding and weight of nymphs in comparison with the control. Just the opposite: nymphs infected with tick-borne encephalitis (TBE) virus produce an opposite reaction--weight decrease under influence of poplar buds as the repellent. Importance of the above phenomena for the ticks distribution and TBE epizootiology is discussed.

Animals↗

[Prevalence of antibodies against Anaplasma phagocytophilum, Babesia microti i Borrelia burgdorferi in adults in North-Eastern Poland].

THE AIM: of the study was to evaluate the seroprevalance of antibodies against Anaplasma phagocytophilum and Babesia Microti in healthy north-eastern Poland, adult population. MATERIAL AND METHODS: The study was conducted in a group of 142 healthy adults (mean age 19-22), bitten by ticks within last 2 years. The control group consisted of 50 adults from central Poland (nonendemic area). The antibody levels for A. phagocytophilum (IgG/Ap-Ab) and B. microti (IgM/Bm-Ab) were evaluated in two series of samples from the same persons (interval 5-6 months) by immunoenzymatic tests (Borrelia Biomedica, Austria), immunofluorescence test (Human Granulotic Ehrlichiosis IFA IgG and Babesia microti IFA IgG from MRL Diagnostics). RESULTS: Positive results for A. phagocytophilum were defined as titres > or =1:256 and for B. microti > or =1:64 and B. burgdorferi > or = 11 BBU/ml. Positive results for IgG B. burgdorferi during the first collection were revealed in 16% (n=24/142) of individuals from endemic area and in 4% (n=2/50) of the control group, which was statistically relevant (p<0,05). IgG A. phagocytophilum antibodies were present in 3,5% (n=5/142) of individuals from the endemic area, but for IgG B. microti antibodies (IgG/Bm-Ab) no positive results were found. No IgG antibodies against A. phagocytophilum and B.microti, were found in individuals from non-endemic area. During the second collection, in individuals from the endemic area, the antibodies against B. burgdorferi were found in 9,8% (n=14/142), IgG A. phagocytophilum antibodies (IgG/Ap-Ab) in 4,9% (n=7/142) and against B. microti (IgG/ Bm-Ab) in 1,4% (n=2/142). The antibodies against B. Burgdorferi were found in 2% (n=1/150) of the control group during the second collection, and no IgG against A. phagocytophilum and B. microti were found. CONCLUSION: [corrected] Evaluating the seroprevalance of the studied antibodies in both collections, a conclusion was drawn that there was no significant increase of antibodies levels directly after the highest exposition to tick bites. None of individuals showed 4-fold antibody level increase between the first and second collection. The seroconversion for IgG/Bm-Ab antibodies was present in 1,4% (n=2/142) of individuals, in those 2 cases a 2-fold antibodies level increase was observed. As far as IgG/Ap-Ab antibodies are concerned the seroconversion was observed in 2,1% (n-3/142), but only one case shown a 3-fold antibodies level increase. No seroconversion of B. burgdorferi antibodies were found in the second collection.

Adult↗

Effect of deer exclusion by fencing on abundance of Amblyomma americanum (Acari: Ixodidae) on Fire Island, New York, USA.

The effects of deer exclusion on northern populations of lone star ticks, Amblyomma americanum, were tested at the Lighthouse Tract, Fire Island, NY, USA, where densities of this species have increased recently. Game fencing was erected to exclude deer from two sites of roughly one ha each, and populations of nymphal and adult A. americanum within were compared with those at control sites outside the exclosures. Percent control of nymphs within vs. outside the exclosures averaged 48.4% in the four years post-treatment, compared to pretreatment values. Percent control varied markedly in different years, suggesting that factors in addition to deer densities had strong effects on population densities of A. americanum. Exclosures of this size did not control adult A. americanum. Effects of deer exclusion in this recently expanded northern population of A. americanum were similar to those that have been reported for southern populations of this species.

Animals↗

Transmission of Borrelia burgdorferi s.l. from mammal reservoirs to the primary vector of Lyme borreliosis, Ixodes ricinus (Acari: Ixodidae), in Sweden.

Factors regulating prevalence of Borrelia burgdorferi s.l. Johnson, Schmid, Hyde, Steigerwalt & Brenner in Ixodes ricinus (L.) were examined during 1991-1992 at Bogesund, near Stockholm in south-central Sweden. Nine species of small and medium-sized mammals (Sorex araneus L., S. minutus L., Neomys fodiens Pennant, Clethrionomys glareolus [Schreber], Microtus agrestis [L.], Apodemus sylvaticus [L.], A. flavicollis [Melchior], Lepus europaeus Pallas, L. timidus L.) were found to infect feeding tick larvae with B. burgdorferi s.l., whereas two species of large mammals (Capreolus capreolus L., Alces alces L.) failed to infect feeding tick larvae with this spirochete. The most important mammalian reservoirs at the study locality were S. araneus and rodents, accounting for 91% of all I. ricinus larvae infected. In view of the great number of potentially effective reservoirs for B. burgdorferi s.l. in Sweden, control of Lyme disease by reduction of abundance of reservoir hosts will be difficult to achieve. We also found that infectivity of a rodent species is related to the number of infesting, potentially infective nymphal I. ricinus. Insectivores and rodents were the most important hosts of larval I. ricinus, whereas most nymphal ticks fed on hares and cervids. Adult I. ricinus were frequently found on all species of hares and cervids examined but never on insectivores and rodents. No single species seemed to be of paramount importance as a source of blood for female ticks. Therefore, control of Lyme disease by reduction of abundance of mammal hosts available for female tick engorgement will probably require massive reductions of numbers of both C. capreolus and L. timidus.

Animals↗

[The relationship of the therapeutic efficacy of immunoglobulin against tick-borne encephalitis to the specific activity of the preparation and the times of its administration].

A controlled clinical trial included 115 patients with meningeal and focal tick-borne encephalitis, 38 of them received nonspecific treatment alone, 77 were given adjuvant intramuscular immunoglobulin against tick-borne encephalitis. The latter are shown to improve much more rapidly than patients treated only symptomatically. When calculating adequate immunoglobulin doses, it is necessary to take in consideration not only the amount of the compound, but also the concentration of the specific antibodies. The authors propose treatment schemes for patients with meningeal and focal tick-borne encephalitis.

Acute Disease↗

Protection against lyme disease spirochete transmission provided by prompt removal of nymphal Ixodes scapularis (Acari: Ixodidae).

Public health recommendations for Lyme disease prevention generally include daily tick checks and prompt removal of attached ticks as a means of decreasing the risk of acquiring Lyme disease in highly endemic regions. In the current study, we determined whether crushing nymphal ticks during removal with forceps increased the risk of B. burgdorferi transmission, what degree of protection from transmission of B. burgdorferi was provided by removal of nymphal Ixodes scapularis Say at specific intervals, and whether commercial devices marketed for tick removal worked when tested against nymphal I. scapularis. Both removal via gentle pressure (26% transmission) or crushing the tick (30% transmission) caused a significant decrease in transmission as compared with the sham control (70% transmission). The degree of protection provided via tick removal decreased steadily up to 60 h of attachment; between 60 and 66 h, a dramatic falloff in protection occurred to the point where no protection was observed at 66 h. Finally, commercial tick removal devices varied widely in their efficacy for the removal of attached nymphal I. scapudaris.

Animals↗

Acaricidal efficacy of cypermethrine (a new synthetic pyrethroid) against Boophilus annulatus ticks in cattle.

Resistance of ticks to acaricides had spread dramatically in recent years, so changing of acaricides periodically is needed to avoid resistant strains. Cypermethrine is a new pyrethroid acaricide recently introduced in the skin parasites control programs in Egypt. Fourteen crossbred cows (Friesian X Egyptian native) were used to assess the acaricidal efficacy of cypermethrine against Boophilus annulatus ticks. Cows were allocated into treated and control groups, each consists of 7 animals. At day 0 before treatment, ticks of more than 4.5 mm in length attached to both treated and control animals were counted and every week thereafter. The average tick number on vaccinated and control animals were counted and the efficacy percentage of cypermethrine was then determined. The number of ticks which laid eggs were counted in treated and control animals and hatching percentage of eggs were then calculated. Spraying of animals with cypermethrine showed that complete elimination of ticks occurred early on the 7th day post-treatment. The average number of ticks was 1673 and that of controls was 1578 at day 0 before treatment. The maximum efficacy (100%) was sustained for up to 7 weeks post-treatment after which the efficacy was slightly dropped and reached 98%. The results of cypermethrine on oviposition and egg hatchability of the ticks which survived treatment were surprising. The percentage of ticks collected from treated cows that succeeded to lay eggs was 22%, the average number of eggs laid per tick was 259 and hatching rate was 8.6%.

Animals↗

Physiological and nutritional responses of steers infested with varying densities of Amblyomma americanum (Acari: Ixodidae).

The effects of varying densities of lone star tick, Amblyomma americanum (L.), on measured physiological parameters of beef cattle in a controlled environment was determined. Steers were infested with either 0, 20, 60, or 120 pairs of adult ticks. Heart rate, respiration, rectal temperature, fecal and urine excretions, and water and feed consumption were monitored daily. Blood samples were taken every 3rd d to measure cortisol, total proteins, urea nitrogen, and glucose levels. Hematocrits were also taken at each blood sampling. Results showed that A. americanum evoked elevated heart rates. The other measured physiological and nutritional responses of parasitized steers were similar to the control steers. These results suggest that tick densities were too low to cause physiological stress under the conditions used in this study. The methodology precluded detection of the parameters measured. A. americanum does not affect the parameters measured, or that fluctuating environmental parameters and varying host nutritional states may play major roles in modulating the effect of A. americanum infestations on cattle in nature.

Animal Nutritional Physiological Phenomena↗

Early and early disseminated phases of Lyme disease in the rhesus monkey: a model for infection in humans.

We demonstrate that Borrelia burgdorferi infection in the rhesus monkey mimics the early and early disseminated phases of human Lyme disease. Clinical, bacteriological, immunological, and pathological signs of infection were investigated during 13 weeks after inoculation of the spirochete. Three animals were given B. burgdorferi (strain JD1) by needle inoculations, six animals were exposed to the bite of B. burgdorferi-infected Ixodes dammini ticks, and three animals were uninfected controls. B. burgdorferi could be recovered from all animals that were given the spirochete. Bacteria were detectable until week 6 postinoculation (p.i.) in blood, until week 8 p.i. in skin biopsies, and at 10 weeks p.i. in the conjunctiva of one of two animals which developed conjunctivitis. Erythema migrans (EM) appeared in one of the three animals infected by needle inoculation and in five of the six animals infected by ticks. Deep dermal perivascular lymphocytic infiltrations (characteristic of human EM) were observed in all animals showing EM clinically. Both EM and conjunctivitis were documented concomitantly with the presence of the spirochete. Lethargy, splenomegaly, and cerebrospinal fluid pleocytosis were also noted in some animals, but the direct connection of these signs with the infection was not shown. The appearance rate of immunoglobulin M and immunoglobulin G antibodies to B. burgdorferi, as well as the antigen spectra recognized, were remarkably similar to those seen in humans. Serum antibodies from infected animals were able to kill B. burgdorferi in vitro in the presence of rhesus complement. The rhesus monkey model appears to be useful for the investigation of the immunology and pathogenesis of Lyme disease and for the development of immunoprophylactic, diagnostic, and chemotherapeutic protocols.

Animals↗

P55, an immunogenic but nonprotective 55-kilodalton Borrelia burgdorferi protein in murine Lyme disease.

Immunization of C3H mice with P55 (previously called S1), a 55-kDa Borrelia burgdorferi antigen that is immunogenic after infection, elicited a strong antibody response but did not protect mice against B. burgdorferi challenge. Mice immunized with a P55 fusion protein in complete Freund's adjuvant developed anti-P55 antibodies, detectable at a titer of 1:10,000 by immunoblotting. To determine, if a protective response had been elicited, P55-vaccinated mice were fed upon by ticks infected with B. burgdorferi. The frequency of B. burgdorferi infection was similar in P55-immunized and control mice, and spirochetes were not destroyed within ticks that fed on P55-vaccinated mice. P55 is an immunogenic antigen that does not induce a protective response in the vertebrate or invertebrate host.

Animals↗

[Active immunization against tick-borne encephalitis virus infection in residents of North-Eastern Poland].

Group consisted of 78 persons was selected among 1587 persons vaccinated against tick-borne encephalitis. Efficiency of vaccination, controlled by measurement of specific IgM and IgG antibodies presence, was evaluated as 70.2% (47.4%-90%). The highest efficiency was observed in urban residents occasionally stayed in forest areas, that showed trace, of antibody level at the begining of study.

Adult↗

Experimental infection of ponies with Borrelia burgdorferi by exposure to Ixodid ticks.

Seven specific-pathogen-free (SPF) ponies, 1-5 years old, were exposed to Borrelia burgdorferi-infected adult ticks while being treated with dexamethasone over 5 consecutive days. One SPF pony (pony No. 178) was first exposed to laboratory-reared nymphs without B. burgdorferi infection and 3 weeks later was exposed to B. burgdorferi-infected adult ticks with concurrent dexamethasone treatment for 5 consecutive days. Four uninfected ponies treated with dexamethasone, exposed to laboratory-reared ticks without B. burgdorferi infection served as uninfected controls. Clinical signs, bacteriologic culture, polymerase chain reaction (PCR) for bacterial DNA, immunologic responses, and gross lesions and histopathologic changes were investigated during the experiment or at necropsy 9 months after tick exposure. In all of the seven challenged ponies, infection with B. burgdorferi was detected from monthly skin biopsies and various tissues at postmortem examination by culture and by PCR. However, pony No. 178 exposed to laboratory-reared nymphs (without B. burgdorferi infection) and challenged with B. burgdorferi-infected adult ticks 2 months later did not develop a B. burgdorferi infection. All of the infected ponies seroconverted. Control ponies and pony No. 178 were negative by culture, PCR, and serology. Except for skin lesions, we failed to induce any significant histopathologic changes in this study. This is the first report of successful tick-induced experimental infection in ponies by exposure to B. burgdorferi-infected ticks. This Lyme disease model will be very useful to evaluate efficacy of vaccines against the Lyme agent and the effect of antibiotic therapy on horses infected with B. burgdorferi.

Animals↗

Protection against Boophilus annulatus infestations in cattle vaccinated with the B. microplus Bm86-containing vaccine Gavac. off.

Tick infestations by Boophilus spp. constitute a major problem for the cattle industry in tropical and subtropical areas of the world. The use of traditional control methods has been only partially successful and tick infestations remain a serious problem. Recently, the gut antigen Bm86 was isolated from B. microplus. Recombinant preparations of this antigen have been used in vaccines for the control of B. microplus infestations. However, in several regions of the world, B. microplus coexists with other Boophilus species, mainly B. annulatus and B. decoloratus. Therefore, there is a need for the simultaneous control of infestations by different Boophilus species. To test the capacity of the P. pastoris-derived Bm86 antigen preparation (Gavac, Heber Biotec S.A., Havana) to control B. annulatus infestations, controlled experiments were conducted in Mexico and Iran. Cattle were vaccinated with Gavac or not vaccinated and then artificially infested with B. annulatus larvae. The results showed for the first time a high protection efficacy (> 99.9%) of Gavac in the control of B. annulatus infestations. These results support the application of Bm86-containing vaccines for the control of Boophilus spp. infestations.

Animals↗