Obesity impairs resistance to Leishmania major infection in C57BL/6 mice

An association between increased susceptibility to infectious diseases and obesity has been described as a result of impaired immunity in obese individuals. It is not clear whether a similar linkage can be drawn between obesity and parasitic diseases. To evaluate the effect of obesity in the immune response to cutaneous Leishmania major infection, we studied the ability of C57BL/6 mice fed a hypercaloric diet (HSB) to control leishmaniasis. Mice with diet-induced obesity presented thicker lesions with higher parasite burden and a more intense inflammatory infiltrate in the infected ear after infection with L. major. There was no difference between control and obese mice in IFN-gamma or IL-4 production by auricular draining lymph node cells, but obese mice produced higher levels of IgG1 and IL-17. Peritoneal macrophages from obese mice were less efficient to kill L. major when infected in vitro than macrophages from control mice. In vitro stimulation of macrophages with IL-17 decreased their capacity to kill the parasite. Moreover, macrophages from obese mice presented higher arginase activity. To confirm the role of IL-17 in the context of obesity and infection, we studied lesion development in obese IL-17R-/- mice infected with L. major and found no difference in skin lesions and the leukocyte accumulation in the draining lymph node is redcuced in knockout mice compared between obese and lean animals. Our results indicate that diet-induced obesity impairs resistance to L. major in C57BL/6 mice and that IL-17 is involved in lesion development.

Obesity is a serious and increasing public health problem, and also induces a spectrum of metabolic disorders. Some diseases are known to be more severe in the presence of obesity. However, the interactions of obesity with the immune response to infectious agents have not been fully explored. In this study, we investigated the response of obese mice to infection with Leishmania major. C57BL/6 mice were fed a hypercaloric diet (HSB) and infected afterward with L. major. In obese mice, lesions were ticker and more ulcerative, and cells from draining lymph nodes produced more IL-17 when compared with cells from lean mice fed a control diet. Macrophages from obese and lean mice were infected in vitro and stimulated with IL-17 to test the role of this cytokine in effect produced by obesity. Macrophages from obese mice were more infected by L. major than the macrophages from control mice and the number of parasites was increased by treatment with IL-17. IL-17R deficient mice treated with hypercaloric diet showed no difference in lesion size when compared to mice fed control diet. Our findings suggest that diet-induced obesity decrease the resistance to L. major infection of C57BL/6 mice and the IL-17 cytokine may be involved in the lesion formation.

Efficacy and safety of sarolaner in the treatment of canine ear mite infestation caused by Otodectes cynotis: a non-inferiority study

BACKGROUND

Various treatments are available for ear mite infestations in dogs.

OBJECTIVE

The efficacy of sarolaner was evaluated against ear mite infestation caused by Otodectes cynotis in dogs and compared with topical moxidectin/imidacloprid in a single-masked, multi-centre field study.

ANIMALS

Client-owned dogs with O. cynotis infestation were treated monthly with oral sarolaner (n = 163) or topical moxidectin/imidacloprid (n = 78).

METHODS

The presence of mites in the ear canals and the clinical signs associated with otoacariasis (including head shaking, pruritus/ear scratching, trauma or alopecia of the pinnae, and erythema, ulceration and debris in the ear canals) was evaluated on days 0, 14 and 30, and, if applicable, on day 60. Dogs were considered cured of mite infestation following one (on day 0) or two (on days 0 and 30) monthly treatments, if no live mites were found in either ear. Non-inferiority was evaluated at days 14 and 30.

RESULTS

Parasitological cure was achieved in 76.4%, 90.5% and 93.3% of the sarolaner-treated and in 53.9%, 63.5% and 66.7% of the moxidectin/imidacloprid-treated dogs on days 14, 30 and 60, respectively. At study completion, on day 60 at the latest, parasitological cure was achieved overall in 99.4% of sarolaner-treated and 87.8% of moxidectin/imidacloprid-treated cases. The parasitological cure rate for sarolaner was non-inferior to moxidectin/imidacloprid at days 14 and 30. The clinical signs of otoacariasis improved throughout the study in both groups. There were no treatment-related adverse events.

CONCLUSIONS

A single oral administration of sarolaner was safe and highly effective in the treatment of O. cynotis infestation in dogs.

First report of spinose ear tick, Otobius megnini (Acari, Argasidae), in Sweden

A dog that had travelled to Sweden was inspected by a veterinarian. In one ear canal a tick was found. It was later identified as a spinose ear tick, Otobius megnini. In this case report we also review the previously known reports of O. megnini in Europe and the recent introduction and spread in Turkey.

Rodent species as natural reservoirs of Borrelia burgdorferi sensu lato in different habitats of Ixodes ricinus in The Netherlands

Rodents are natural reservoirs for human pathogenic spirochaetes of the Borrelia burgdorferi complex [B. burgdorferi sensu lato (s.l.)], and the pathogens are transmitted by Ixodes ricinus ticks to humans in The Netherlands. B. burgdorferi s.l. infection prevalence in questing ticks, rodents, and ticks feeding on these rodents, all sampled within the same short time span of five days in three different areas in The Netherlands, were compared in order to establish the relationship between ticks, reservoir hosts, and B. burgdorferi s.l. Questing nymphs were found in all 3 areas and numbers differed per area and even per site within areas. Infection prevalence in questing nymphs ranged between 0 and 20%. Apodemus sylvaticus and Myodes glareolus were the dominant rodents captured, and their numbers differed per area. Infection prevalence, determined by ear biopsies, ranged between 0 and 33.3% for both rodent species. Larvae were most frequently found feeding on these rodents, and their Borrelia infection prevalence ranged between 0 and 6.3% (A. sylvaticus) and between 0 and 29.4% (M. glareolus). The burden of nymphs feeding on rodents was low and varied per area with only 2 of 42 nymphs infected. Comparisons made on the basis of infection prevalence indicated that there was no clear relationship between rodents and questing nymphs when sampled within the same short time span. However, a possible relationship was present when questing ticks were sampled over longer periods in time (months) within or near the same areas (range of infection prevalence between 3.7 and 39.4). Confounding factors thus play a role in the interaction between rodents, ticks, and B. burgdorferi s.l., and it is very likely that other reservoir host species are responsible for the observed fluctuations. It is concluded that the local variations in rodent-Borrelia-tick interactions only partially explain the Lyme borreliosis risk in the sites studied and that other ecological determinants, notably vertebrate hosts and vegetation structure, should be incorporated in future studies of Lyme borreliosis risk.

Leishmania majorinfection in the fat sand ratPsammomys obesusin Tunisia: interaction of host and parasite populations

The causative agent of cutaneous leishmaniasis, Leishmania major, was studied in a Tunisian population of the fat sand rat, Psammomys obesus. Seasonal changes in the abundances of parasite and host were monitored in a longitudinal field survey lasting 21 months. Overall, 566 P. obesus, collected during 10 trapping sessions between May 1995 and January 1997, were examined. Analysis of prevalence, using logistic regression, revealed that extrinsic factors, such as season and climatic conditions, and intrinsic factors, such as host age, have a combined effect. Leishmania major showed a seasonal pattern, with most transmission occurring in late summer and in autumn, when prevalences were 7.5- and 6.6-fold higher, respectively, than in spring. Prevalence peaked, at 70%, in September 1995 and then decreased to 0% in June 1996. The same temporal fluctuation was observed during the second study year, albeit among prevalences that were relatively low because of unusually dry conditions. Prevalence was highly dependent on the age of the P. obesus, and season and age acted in synergy so that the rodents were highly infected in late summer and in autumn. Prevalence was not correlated with the relative density of the P. obesus and also appeared independent of gender. Although the ear lesions observed on 378 sand rats during a 1-year survey were closely associated with Leishmania infection, such lesions were not good predictors of infection, as 35% of the rodents found to be infected had no visible lesions on their ears. The prevalences of Leishmania infection observed in this study, among P. obesus living in monospecific colonies, were generally lower than those observed in other studies of P. obesus. It seems possible that P. obesus living in monospecific colonies could have a lesser role in propagating the parasite than those living in plurispecific colonies of rodents, and act as an 'epidemiological sink'.

Antibody responses to Sarcoptes scabiei apolipoprotein in a porcine model: relevance to immunodiagnosis of recent infection

No commercial immunodiagnostic tests for human scabies are currently available, and existing animal tests are not sufficiently sensitive. The recombinant Sarcoptes scabiei apolipoprotein antigen Sar s 14.3 is a promising immunodiagnostic, eliciting high levels of IgE and IgG in infected people. Limited data are available regarding the temporal development of antibodies to Sar s 14.3, an issue of relevance in terms of immunodiagnosis. We utilised a porcine model to prospectively compare specific antibody responses to a primary infestation by ELISA, to Sar s 14.3 and to S. scabiei whole mite antigen extract (WMA). Differences in the antibody profile between antigens were apparent, with Sar s 14.3 responses detected earlier, and declining significantly after peak infestation compared to WMA. Both antigens resulted in >90% diagnostic sensitivity from weeks 8-16 post infestation. These data provide important information on the temporal development of humoral immune responses in scabies and further supports the development of recombinant antigen based immunodiagnostic tests for recent scabies infestations.

Nasal, oral and ear swabs for canine visceral leishmaniasis diagnosis: new practical approaches for detection of Leishmania infantum DNA

Background

The aim of this study was to evaluate the potential use of nasal, oral, and ear swabs for molecular diagnosis of canine visceral leishmaniasis (CVL) in an endemic urban area in Brazil.

Methodology/Principal Findings

Sixty-two naturally infected and ten healthy dogs were enrolled in this study. Bone marrow aspirates, peripheral blood, skin biopsy, and conjunctival, nasal, oral, and ear swabs were collected. All samples, except blood, were submitted to conventional PCR (cPCR) and quantitative real time PCR (qPCR) to detect and quantify Leishmania infantum DNA, respectively. All dogs were submitted to thorough clinical analysis and were included based on a combination of serological (ELISA immunoassay and immunofluorescent antibody test) and parasitological methods. The cPCR positivity obtained from nasal swab samples was 87% (54/62), equivalent to those from other samples (P>0.05). Positive results were obtained for 79% (22/28) in oral swabs and 43% (12/28) in ear swab samples. A significant difference was observed between these data (P = 0.013), and the frequency of positive results from oral swab was equivalent to those from other samples (P>0.05). The use of ear swab samples for cPCR assays is promising because its result was equivalent to skin biopsy data (P>0.05). The qPCR data revealed that parasite loads in mucosal tissues were similar (P>0.05), but significantly lower than the parasite burden observed in bone marrow and skin samples (P<0.05).

Conclusions

Nasal and oral swab samples showed a high potential for the qualitative molecular diagnosis of CVL because their results were equivalent to those observed in samples collected invasively. Considering that mucosae swab collections are painless, noninvasive, fast and practical, the combination of these samples would be useful in massive screening of dogs. This work highlights the potential of practical approaches for molecular diagnosis of CVL and human leishmaniasis infections.

Visceral leishmaniasis (VL) is an important public health problem in different regions of the world. It presents high lethality in human cases without suitable treatment and is considered one of the most important disorders in dogs, the main domestic reservoir of the etiological agent of VL (Leishmania infantum). Most cases of VL in Latin America occur in Brazil, and control campaigns have not shown satisfactory results. The diagnosis of human and canine infection is critical for making decisions regarding surveillance and control policies. In this work, we propose a non-invasive collection method of mucosal and epithelial cells for the molecular diagnosis of canine VL by conventional polymerase chain reaction (cPCR) and for the estimation of parasite load by quantitative real time PCR (qPCR). We used nasal, oral, and ear swabs as practical, simple, painless and fast alternatives for collecting samples. These procedures are according to the need of more simplified methods for detecting L. infantum infection by using robust diagnostic techniques such as cPCR and qPCR. Additionally, potential applications for diagnosing human VL are highlighted.

Ixodes ricinus infestation in free-ranging cervids in Norway--a study based upon ear examinations of hunted animals

Prevalence, abundance and instar composition of Ixodes ricinus as found on one ear collected from 1019 moose (Alces alces), red deer (Cervus elaphus) and roe deer (Capreolus capreolus), shot during hunting (August-December) 2001-2003, are reported. The animals originated from 15 coastal municipalities (CM), seven municipalities bordering to coastal municipalities (BCM) and four inland municipalities (IM), in Norway, between latitudes 58-66° N. I. ricinus occurred endemically in all CM and BCM up to 63°30' N, whereas it was non-endemic further north and in the IM. This geographical distribution of the tick along the coast of southern Norway was largely in accordance with that reported as far back as the 1940s. Our results therefore did not indicate any large scale northwards expansion of I. ricinus in Norway during the 60 year-period between the two studies. However, the prevalence of infestation and tick abundance were significantly higher in CM as compared to BCM. The prevalence and abundance by month were highest during August and September, gradually decreasing towards December. The considerable prevalence of ticks in November, as well as findings in December, would seem to indicate a prolonged tick season as compared with the studies carried out 60 years ago. A total of 8920 ticks were isolated from 439 of the 603 animals examined in endemic municipalities, and the maximum number of ticks found on one single ear was 204. Attached adult ticks were primarily found among the long hairs at base of the ear, whereas nymphs and larvae were seen all over the outer surface of the pinna, for larvae especially at the edge and tip of the ear. Nymphs were the dominant instar, constituting 74% of the total tick count. The proportion of larvae and adult ticks was 13% and 12%. A significantly higher proportion of adult ticks and lower proportion of immature stages were found in moose, as compared to red deer and roe deer. The same apparently size-associated preference of adult ticks was also found for adult animals (all species) as compared to calves. Other grossly detected ectoparasites included the lice Solenopotes burmeisteri in red deer and Damalinia meyeri in roe deer, and the deer ked fly, Lipoptena cervi, in moose and roe deer. This is believed to be the first systematic study on the instar composition by I. ricinus infestation in free-ranging cervids. The examination of ears from hunted cervids should be recognized as a rational way of obtaining data on the geographical distribution and abundance of this tick in nature.

The human aural myiasis caused by Lucilia sericata

Myiasis is a rare, worldwide, human disease with seasonal variation, caused by developing larvae of a variety of fly species. It can be dangerous when infestations penetrate into the brain. In the available literature, we have found only a few papers concerning ear myiasis caused by Lucilia sericata. Here, we report 2 cases of aural myiasis. Early intervention (surgical removal, occlusion) in these cases should prevent complications. Larvae, for further examination, should be killed by immersion in very hot water, then preserved in an ethanol.

Traumatic myiasis in dogs caused by Wohlfahrtia magnifica and its importance in the epidemiology of wohlfahrtiosis of livestock

In the province of Al Hoceima, northern Morocco, and on two farms in Hungary, dogs were inspected for the presence of traumatic myiasis. Nine and four infested dogs were found in Morocco and Hungary, respectively. All the larvae and adults reared from them in the laboratory were identified as Wohlfahrtia magnifica (Schiner) (Diptera: Sarcophagidae). To our knowledge, these are the first cases of wohlfahrtiosis in dogs to be reported in these countries. All infested animals lived close to livestock, where wohlfahrtiosis was endemic. Infested body sites included limbs (six cases), external genitalia (two), ears (three), nose (one) and neck (one). Developing larvae caused severe welfare problems and tissue destruction in most cases. Although the number of cases reported here is small, wohlfahrtiosis in dogs may be very important from an epidemiological perspective because farm and stray dogs can act as both reservoirs and carriers of this parasitic fly species. Therefore, education of dog owners concerning the risk factors in endemic regions is recommended in order to reduce the prevalence of wohlfahrtiosis in dogs and thereby in livestock. Both owners and veterinarians should pay regular attention to any wounds and to the natural orifices of dogs, especially during the fly seasons.

Difficulties to control natural infestation with Otobius megnini (Acari: Argasidae) nymphs in cattle with systemic biocides

A study was carried out to determine the efficacy of topical eprinomectin against nymphal infestation of Otobius megnini in cattle, where a group of 14 individuals were treated with a dose of 0.5mg/per kg of body weight applied on the dorsal midline, and a group of 14 individuals remained as control. Tick burdens between treated and control groups showed no statistically significant differences (P>0.05), and the mortality of the nymphs was similar in both groups (P: 0.828). All females obtained from nymphs of both groups were able to copulate with males from the corresponding group and laid eggs that produced visually normal larvae. The failure of eprinomectin and other biocides applied per os or by injection to control nymphs of O. megnini in cattle indicate that sanitary measures and applications of biocides into the ears would represent the most reasonable approach to control of this tick on cattle.

Immunity to distinct sand fly salivary proteins primes the anti-Leishmania immune response towards protection or exacerbation of disease

Background

Leishmania parasites are transmitted in the presence of sand fly saliva. Together with the parasite, the sand fly injects biologically active salivary components that favorably change the environment at the feeding site. Exposure to bites or to salivary proteins results in immunity specific to these components. Mice immunized with Phlebotomus papatasi salivary gland homogenate (SGH) or pre-exposed to uninfected bites were protected against Leishmania major infection delivered by needle inoculation with SGH or by infected sand fly bites. Immunization with individual salivary proteins of two sand fly species protected mice from L. major infection. Here, we analyze the immune response to distinct salivary proteins from P. papatasi that produced contrasting outcomes of L. major infection.

Methodology/Principal Findings

DNA immunization with distinct DTH-inducing salivary proteins from P. papatasi modulates L. major infection. PpSP15-immunized mice (PpSP15-mice) show lasting protection while PpSP44-immunized mice (PpSP44-mice) aggravate the infection, suggesting that immunization with these distinct molecules alters the course of anti-Leishmania immunity. Two weeks post-infection, 31.5% of CD4⁺ T cells produced IFN-γ in PpSP15-mice compared to 7.1% in PpSP44-mice. Moreover, IL-4-producing cells were 3-fold higher in PpSP44-mice. At an earlier time point of two hours after challenge with SGH and L. major, the expression profile of PpSP15-mice showed over 3-fold higher IFN-γ and IL-12-Rβ2 and 20-fold lower IL-4 expression relative to PpSP44-mice, suggesting that salivary proteins differentially prime anti-Leishmania immunity. This immune response is inducible by sand fly bites where PpSP15-mice showed a 3-fold higher IFN-γ and a 5-fold lower IL-4 expression compared with PpSP44-mice.

Conclusions/Significance

Immunization with two salivary proteins from P. papatasi, PpSP15 and PpSP44, produced distinct immune profiles that correlated with resistance or susceptibility to Leishmania infection. The demonstration for the first time that immunity to a defined salivary protein (PpSP44) results in disease enhancement stresses the importance of the proper selection of vector-based vaccine candidates.

In vector-borne diseases, the role of vectors has been overlooked in the search for vaccines. Nonetheless, there is a body of evidence showing the importance of salivary proteins of vectors in pathogen transmission. Leishmaniasis is a neglected vector-borne disease transmitted by sand flies. Pre-exposure to sand fly saliva or immunization with a salivary protein protected mice against cutaneous leishmaniasis. Using DNA immunization we investigated the immune response induced by abundant proteins within the saliva of the sand fly Phlebotomus papatasi. We found that one salivary protein protected while another exacerbated L. major infection, suggesting that the type of immune response induced by specific salivary proteins can prime and direct anti-Leishmania immunity. This stresses the importance of the proper selection of vector-based vaccine candidates. This work validates the powerful protection that can be acquired through vaccination with the appropriate salivary molecule and more importantly, shows that this protective immune response is efficiently recalled by sand fly bites, the natural route of transmission.

Optimization of topical therapy for Leishmania major localized cutaneous leishmaniasis using a reliable C57BL/6 Model

Background

Because topical therapy is easy and usually painless, it is an attractive first-line option for the treatment of localized cutaneous leishmaniasis (LCL). Promising ointments are in the final stages of development. One main objective was to help optimize the treatment modalities of human LCL with WR279396, a topical formulation of aminoglycosides that was recently proven to be efficient and safe for use in humans.

Methodology/Principal Findings

C57BL/6 mice were inoculated in the ear with luciferase transgenic L. major and then treated with WR279396. The treatment period spanned lesion onset, and the evolution of clinical signs and bioluminescent parasite loads could be followed for several months without killing the mice. As judged by clinical healing and a 1.5-3 log parasite load decrease in less than 2 weeks, the 94% efficacy of 10 daily applications of WR279396 in mice was very similar to what had been previously observed in clinical trials. When WR279396 was applied with an occlusive dressing, parasitological and clinical efficacy was significantly increased and no rebound of parasite load was observed. In addition, 5 applications under occlusion were more efficient when done every other day for 10 days than daily for 5 days, showing that length of therapy is a more important determinant of treatment efficacy than the total dose topically applied.

Conclusions/Significance

Occlusion has a significant adjuvant effect on aminoglycoside ointment therapy of experimental cutaneaous leishmaniasis (CL), a concept that might apply to other antileishmanial or antimicrobial ointments. Generated in a laboratory mouse-based model that closely mimics the course of LCL in humans, our results support a schedule based on discontinuous applications for a few weeks rather than several daily applications for a few days.

When initiating the cutaneous disease named cutaneous leishmaniasis (CL), Leishmania parasites develop within the parasitophorous vacuoles of phagocytes residing in and/or recruited to the dermis, a process leading to more or less chronic dermis and epidermis-damaging inflammatory processes. Topical treatment of CL could be a mainstay in its management. Any improvements of topicals, such as new vehicles and shorter optimal contact regimes, could facilitate their use as an ambulatory treatment. Recently, WR279396, a third-generation aminoglycoside ointment, was designed with the aim to provide stability and optimal bioavailability for the molecules expected to target intracellular Leishmania. Two endpoints were expected to be reached: i) accelerated clearance of the maximal number of parasites, and ii) accelerated and stable repair processes without scars. A mouse model of CL was designed: it relies on the intradermal inoculation of luciferase-expressing Leishmania, allowing for in vivo bioluminescence imaging of the parasite load fluctuation, which can then be quantified simultaneously with the onset and resolution of clinical signs. These quantitative readout assays, deployed in real time, provide robust methods to rapidly assess efficacy of drugs/compounds i) to screen treatment modalities and ii) allow standardized comparison of different therapeutic agents.

Despite increased CD4+Foxp3+ cells within the infection site, BALB/c IL-4 receptor-deficient mice reveal CD4+Foxp3-negative T cells as a source of IL-10 in Leishmania major susceptibility

BALB/c IL-4Ralpha(-/-) mice, despite the absence of IL-4/IL-13 signaling and potent Th2 responses, remain highly susceptible to Leishmania major substain LV39 due exclusively to residual levels of IL-10. To address the contribution of CD4(+)CD25(+) T regulatory (Treg) cells to IL-10-mediated susceptibility, we depleted CD4(+)CD25(+) cells in vivo and reconstituted IL-4Ralpha x RAG2 recipients with purified CD4(+)CD25(-) T cells. Although anti-CD25 mAb treatment significantly decreased parasite numbers in IL-4Ralpha(-/-) mice, treatment with anti-IL-10R mAb virtually eliminated L. major parasites in both footpad and dermal infection sites. In addition, IL-4Ralpha x RAG2 mice reconstituted with CD4(+) cells depleted of CD25(+) Treg cells remained highly susceptible to infection. Analysis of L. major-infected BALB/c and IL-4Ralpha(-/-) inflammatory sites revealed that the majority of IL-10 was secreted by the CD4(+)Foxp3(-) population, with a fraction of IL-10 coming from CD4(+)Foxp3(+) Treg cells. All T cell IFN-gamma production was also derived from the CD4(+)Foxp3(-) population. Nevertheless, the IL-4Ralpha(-/-)-infected ear dermis, but not draining lymph nodes, consistently displayed 1.5- to 2-fold greater percentages of CD4(+)CD25(+) and CD4(+)Foxp3(+) Treg cells compared with the BALB/c-infected dermis. Thus, CD4(+)Foxp3(-) T cells are a major source of IL-10 that disrupts IFN-gamma activity in L. major-susceptible BALB/c mice. However, the increase in CD4(+)Foxp3(+) T cells within the IL-4Ralpha(-/-) dermis implies a possible IL-10-independent role for Treg cells within the infection site, and may indicate a novel immune escape mechanism used by L. major parasites in the absence of IL-4/IL-13 signaling.

Plasmodium sporozoites trickle out of the injection site

Plasmodium sporozoites make a remarkable journey from the skin, where they are deposited by an infected Anopheline mosquito, to the liver, where they invade hepatocytes and develop into exoerythrocytic stages. Although much work has been done to elucidate the molecular mechanisms by which sporozoites invade hepatocytes, little is known about the interactions between host and parasite before the sporozoite enters the blood circulation. It has always been assumed that sporozoites rapidly exit the injection site, making their interactions with the host at this site, brief and difficult to study. Using quantitative PCR, we determined the kinetics with which sporozoites leave the injection site and arrive in the liver and found that the majority of infective sporozoites remain in the skin for hours. We then performed sub-inoculation experiments which confirmed these findings and showed that the pattern of sporozoite exit from the injection site resembles a slow trickle. Last, we found that drainage of approximately 20% of the sporozoite inoculum to the lymphatics is associated with a significant enlargement of the draining lymph node, a response not observed after intravenous inoculation. These findings indicate that there is ample time for host and parasite to interact at the inoculation site and are of relevance to the pre-erythrocytic stage malaria vaccine effort.

Leishmania-derived murine monocyte chemoattractant protein 1 enhances the recruitment of a restrictive population of CC chemokine receptor 2-positive macrophages

Transgenic Leishmania parasites that encode the murine chemokine monocyte chemoattractant protein 1 (MCP-1) were generated. These parasites transcribed MCP-1 mRNA and secreted MCP-1 protein. Infection of BALB/c, C57BL/6, or MCP-1 knockout (KO) mice with these parasites resulted in minimal lesion development with fewer parasites in the infected foot, lymph node, and spleen compared to wild-type-infected mice. In contrast, transgenic parasites caused substantial lesions with relatively high numbers of parasites in CC chemokine receptor 2 (CCR2) KO mice, indicating that the parasites are viable and healthy and that the lack of lesion development is CCR2 dependent. Prior infection of mice with transgenic parasites offered no protection to subsequent wild-type L. major challenge, suggesting that the transgenic parasites are controlled by an early innate immune response. Consistent with innate immunity, flow cytometry of cells from the ears of mice infected with transgenic parasites revealed an increase in the number of CCR2-positive macrophages by day 7 postinfection. The enumeration of transgenic parasites in ear lesions demonstrated a significant reduction in parasite numbers, which coincided with the increased CCR2-positive macrophage migration. CCR2-positive macrophages isolated from ears of mice infected with transgenic parasites contained virtually no parasites. In vitro studies revealed that optimal parasite killing required the recruitment of CCR2-positive macrophages, followed by stimulation with a combination of both MCP-1 and gamma interferon (IFN-gamma). This work suggests that the parasite-derived MCP-1 can recruit a restrictive population of CCR2-positive macrophages into lesions that can be optimally stimulated by MCP-1 and IFN-gamma to efficiently kill Leishmania parasites.

Relationship between Canine Visceral Leishmaniosis and the Leishmania (Leishmania) chagasi Burden in Dermal Inflammatory Foci

The skin is the first point of contact with organisms of the genus Leishmania from sand fly vectors, and apparently normal skin of sick dogs harbours amastigote forms of Leishmania chagasi. In relation to canine visceral leishmaniosis (CVL), the ear skin was examined in 10 uninfected dogs (UDs) and in 31 dogs dogs naturally infected with L. chagasi. The infected animals consisted of 10 symptomless dogs (SLDs), 12 mildly affected dogs (MADs) and nine affected dogs (ADs). A higher parasite burden was demonstrated in ADs than in SLDs by anti-Leishmania immunohistochemistry (P<0.01), and by Leishman Donivan Unit (LDU) indices (P=0.0024) obtained from Giemsa-stained impression smears. Sections stained with haematoxylin and eosin demonstrated a higher intensity of inflammatory changes in ADs than in SLDs (P<0.05), and in the latter group flow cytometry demonstrated a correlation (P=0.05/r=0.7454) between the percentage of CD14(+) monocytes in peripheral blood and chronic dermal inflammation. Extracellular matrix assessment for reticular fibres by staining of sections with Masson trichrome and Gomori ammoniacal silver demonstrated a decrease in collagen type I and an increase in collagen type III as the clinical signs increased. The data on correlation between cellular phenotypes and histological changes seemed to reflect cellular activation and migration from peripheral blood to the skin, mediated by antigenic stimulation. The results suggested that chronic dermal inflammation and cutaneous parasitism were directly related to the severity of clinical disease.

Down-regulation of gp63 level in Leishmania amazonensis promastigotes reduces their infectivity in BALB/c mice

Episomal expression of the major surface glycoprotein (gp63) sense and antisense mRNAs in Leishmania amazonensis was found previously to modulate the expression of this molecule as well as its infection of macrophages in vitro. Here, we evaluated the in vivo infectivity of these transfectants in BALB/c mice. Antisense downregulation of gp63 renders this parasite sensitive to complement-mediated lysis and less infective to mice, as indicated by a delay in lesion development and a significant reduction in lesion size and parasite loads at the site of inoculation and in the draining lymph nodes (DLNs). CD4+ cells at the site of inoculation decreased in number more rapidly and were 2-fold less numerous than those in controls by week 4. The number of IFN-gamma-positive cells was higher, while IL-10 positive cells were undetectable. In DLNs, CD4+ cells were higher in number, and the profile of cytokine-positive cells followed essentially the same patterns--found at the site of inoculation. These results suggest that the downregulation of gp63 increases extracellular lysis of the mutants by complement, in the in vivo environment, and reduces their infection of macrophages, resulting in a type 1 immune response seen at the site of inoculation and DLNs.

Is the reactive oxygen species-dependent-NF-κB activation observed in iron-loaded BALB/c mice a key process preventing growth of Leishmania major progeny and tissue-damage?

Systemic iron delivery to BALB/c mice, at time points surrounding the inoculation of 1000 Leishmania major metacyclic promastigotes intradermally in the ear results in the complete absence of onset and further development of ear lesion. In these iron-protected mice, the L. major intracellular progeny remains very low in both the ear and the draining lymph node. The iron-induced protective status is associated with a diphenyleneiodonium-sensitive sustained increased oxidative burst. We showed that iron-loaded mice developed no lesions at the site of the primary inoculation and were also resistant to reinoculation at a distant site (intradermal re-inoculation of 1000 metacyclic promastigotes in the contra-lateral ear). Interestingly, in the lymph node cell population recovered from iron-loaded mice at weeks 8 and 12 after the second parasite inoculation, and whatever the protective status studied--primary or resistant to re-inoculation--three potentially related features were observed: (i) NF-kappaB activation, (ii) enhanced TCR-mediated T lymphocyte proliferation, and (iii) high number of IFN-gamma-positive CD4(+)T cells. These results show a putative role of an iron-induced reactive oxygen species-dependent activation of NF-kappaB in the development of protective immunity against L. major.

The prevention of the growth of Leishmania major progeny in BALB/c iron-loaded mice: a process coupled to increased oxidative burst, the amplitude and duration of which depend on initial parasite developmental stage and dose

BALB/c mice were given or not iron around the time of intradermal parasite inoculation, in their ears, of either 10(6) stationary-phase (designated "high-dose model") or 10(3)Leishmania major metacyclic promastigotes (designated "low-dose model"). Iron-loaded mice in the high-dose model displayed delayed and limited pathogenic processes, whereas in the low-dose model, the mice remained ear lesion-free over 12 months post-parasite inoculation. These phenotypes were coupled to an increased leukocyte oxidative burst displayed mainly by neutrophils: it was early and transient in the high-dose model, whereas it was sustained in the low-dose model. In the latter model, injection of an antioxidant (diphenyleneiodonium chloride) at week 2 post-L. major inoculation resulted in a significant decrease in oxidative burst and reversed the protective status. The increased and sustained oxidative burst displayed by the neutrophils, the sustained presence of IL-12 (p40/p70)-positive leukocytes in the ear dermis, the low number of inflammatory leukocytes in the ear dermis and their concomitant high number in the draining lymph node are three related features that likely contribute to the shaping of the protective status, the onset and dynamic maintenance of which are antioxidant sensitive.

Efficacy of an injectable formulation of eprinomectin against Psoroptes cuniculi, the ear mange mite in rabbits

Thirty rabbits naturally infected with ear mange mite, Psoroptes cuniculi, were subcutaneously administrated with a single dose of eprinomectin at 100, 200 and 300 microg/kg body weight or vehicle on day 0. The extent of lesions was scored on day -6 (prior to treatment), day 0 (treated), days 7, 14, 21, 28 and 35, the ear scabs were collected simultaneously; mites in scabs were examined and counted. The results showed that a single dose of eprinomectin at 200 or 300 microg/kg body weight following subcutaneous administration was able to eliminate P. cuniculi infection in rabbits, and a dose of eprinomectin at 100 microg/kg could significantly reduce mites but was unable to eliminate P. cuniculi.

Feline leishmaniasis due to Leishmania (Leishmania) amazonensis in Mato Grosso do Sul State, Brazil

A case of leishmaniasis in a domestic cat (Felis domesticus) is described. The animal showed a single, nodular lesion on the nose and many nodules of different size on the ears and digital regions of all the paws. Diagnosis was made by microscopic detection of amastigotes in Giemsa-stained smears from the lesions. By monoclonal antibodies the aetiological agent was identified as Leishmania (Leishmania) amazonensis, one of the seven species implicated in human leishmaniasis in Brazil. The clinical signs in feline leishmaniasis are unspecific and similar to those observed in other diseases such as cryptococcosis and in sporotrichosis, commonly found in cats. Leishmaniasis should therefore, be added to the differential diagnosis by feline veterinary practitioners and adequate investigations should carried out for dermal leishmaniasis in the area where the feline infection is detected.

Dendritic cell populations in Leishmania major-infected skin and draining lymph nodes

Using a metacyclic promastigote ear infection model of cutaneous leishmaniasis, we examined the phenotype, parasite load, and cytokine production of dendritic cells in the skin and draining lymph nodes of resistant C57BL/6J and susceptible BALB/c mice. Five dendritic cell populations were isolated from the skin and lymph nodes, and the main difference between the groups of mice was an increased number of plasmacytoid dendritic cells in the lymph nodes of the susceptible mice. Although similar cell types were present in the skin emigrants of both strains, there was a 10-fold larger number of cells in BALB/c mouse skin early in infection than in C57BL/6J mouse skin. None of the dendritic cells in the lymph nodes harbored parasites until 3 weeks after infection, with the Langerhans cells having the largest load and the plasmacytoid dendritic cells having the smallest load but the longest lasting infection. Although parasites could be detected in the lymph nodes a few hours after infection, none of the skin emigrants harbored parasites, indicating that they are not the vehicle that ferries the parasites from the skin to the lymph nodes. The presence of larger numbers of plasmacytoid cells in infected BALB/c mice, the more protracted infection of these cells, and their production of alpha interferon point to a complex and important role for the plasmacytoid cells in leishmaniasis.

The site of Leishmania major infection determines disease severity and immune responses

Inbred strains of mice infected with Leishmania major have been classified as genetically resistant or susceptible on the basis of their ability to cure their lesions, the parasite burden in the draining lymph nodes, and their type of T helper cell immune responses to the parasite. Using the intradermal infection at the base of the tail and the ear pinna, we compared for the first time the above-mentioned parameters in six strains of mice infected with metacyclic promastigotes, and we show that the severity of disease depends greatly on the site of infection. Although the well-documented pattern of disease susceptibility of BALB/c and C57BL/6 mice described for the footpad and base-of-the-tail models of leishmaniasis were confirmed, C3H/HeN and DBA/2 mice, which are intermediate and susceptible, respectively, in the tail and other models, were resistant to ear infection. Moreover, in the CBA/H, C3H/HeN, C57BL/6J, and DBA/2 mouse strains, there was little correlation between the pattern of cytokines produced and the disease phenotype observed at the ear and tail sites. We conclude that the definition of susceptibility and the immune mechanisms leading to susceptibility or resistance to infection may differ substantially depending on the route of infection.

Amblyomma cajennense ticks induce immediate hypersensitivity in horses and donkeys

Since host immune reaction to ticks interferes with tick-borne pathogen transmission, it is important to recognize naturally occurring tick-host immune relationships to better understand the epidemiology of such infectious diseases. Amblyomma cajennense is an important tick-borne disease vector in the Neotropical region and horses maintain it in domestic environments. In the present work intradermal testing of A. cajennense tick exposed horses and donkeys using crude tick antigens was used to evaluate the type of hypersensitivity induced by infestations. Animals sensitized by A. cajennense infestation displayed an immediate hypersensitivity reaction at the antigen inoculation site. Foals sensitized with experimental infestations and field sensitized horses presented the most intense reactions (40% of ear thickness increase). Field sensitized donkeys presented less intense reaction reaching no more than 22% of mean thickness increase. Control horses (non-sensitized) had the least intense reaction, with a peak of no more than 12% of increase. The presence of a prominent immediate hypersensitivity in equids sensitized experimentally or by field infestations indicates that A. cajennense ticks induce in this host an immune response that is associated with IgE production and which is known to be inappropriate against intracellular pathogens. Differences observed between horses and donkeys are discussed.

Otodectes cynotis (Acari: Psoroptidae): examination of survival off-the-host under natural and laboratory conditions

The biological and environmental factors affecting survival off-the-host of Otodectes cynotis (Acari: Psoroptidae) ear mites were investigated under natural and laboratory conditions. From November 2000 to November 2002 mites were collected monthly from cats and divided into four groups according to sex and stage. In laboratory conditions, the mites were placed in an incubator with a steady 95% relative humidity (r.h.), a 10 degrees C. All the plates were examined by stereomicroscopy every 24 h until all the mites had died. The data were analysed statistically by multiple linear regression and survival analysis. At 10 degrees C, the maximum survival time of mites was between 15 and 17 days, while at 34 degrees C, it was between 5 and 6 days. The maximum survival time of adult females was significantly longer than that of other stages. No differences were observed in maximum survival times of mites that had been offered food and those that had not, or in the time (in days) to reach 50% mortality (LT50). When exposed to environmental conditions, the maximum survival time (12 days) was observed at temperatures ranging from 12.3 to 14.2 degrees C and r.h.s between 57.6 and 82.9%. Multiple regression analysis showed that temperature alone influenced the maximum survival time and LT50 of mites, and that the rate of survival declined linearly with increasing mean temperature. This basic understanding of off-host survival suggests that, places which have been inhabited by infected animals may need to be disinfected or remain vacated for at least 12 days before occupancy by clean cats or dogs.

Comparison of the A2 gene locus in Leishmania donovani and Leishmania major and its control over cutaneous infection

In Old World Leishmania infections, Leishmania donovani is responsible for fatal visceral leishmaniasis, and L. major is responsible for non-fatal cutaneous leishmaniasis in humans. The genetic differences between these species which govern the pathology or site of infection are not known. We have therefore carried out detailed analysis of the A2 loci in L. major and L. donovani because A2 is expressed in L. donovani but not L. major, and A2 is required for survival in visceral organs by L. donovani. We demonstrate that although L. major contains A2 gene regulatory sequences, the multiple repeats that exist in L. donovani A2 protein coding regions are absent in L. major, and the remaining corresponding A2 sequences appear to represent non-expressed pseudogenes. It was possible to restore amastigote-specific A2 expression to L. major, confirming that A2 regulatory sequences remain functional in L. major. Although L. major is a cutaneous parasite in rodents and humans, restoring A2 expression to L. major inhibited its ability to establish a cutaneous infection in susceptible BALB/c or resistant C57BL6 mice, a phenotype typical of L. donovani. There was no detectable cellular immune response against L. major after cutaneous infection with A2-expressing L. major, suggesting that the lack of growth was not attributable to acquired host resistance but to an A2-mediated suppression of parasite survival in skin macrophages. These observations argue that the lack of A2 expression in L. major contributed to its divergence from L. donovani with respect to the pathology of infection.

Efficacy of selamectin administered topically in the treatment of feline otoacariosis

The efficacy of a novel avermectin, selamectin (Stronghold, Pfizer), was evaluated against naturally acquired aural infestations of Otodectes cynotis. Selamectin was administered topically in a single spot to the skin of each animal's back at the base of the neck in front of the scapulae at a minimum dosage of 6mgkg(-1). Thirty cats of a cattery of 120 animals with an endemic infestation were treated on days 0 and 30. Including untreated control cats was therefore not possible because of animal welfare consideration. Clinical examination and visualization of mites by otoscopic examination of the external ear canal and microscopic examination of aural debris/exudate were performed twice weekly from days 0 to 30. On day 0 (and day 28 if the ears canals were erythematous), a swab was taken from each canal and sent to bacteriology and mycology units for detection and identification of bacteria (Staphylococcus mainly) and yeast (Malassezia pachydermatis only). Selamectin was safe, parasites were killed before day 3 and eliminated before day 17. Selamectin was 100% effective against natural aural infestations, even if erythema (26-33% of cats) and scratch reflex (23-40% of cats) persisted for 2 weeks after the cats tested negative for mites.

Preventing transmission of sarcoptic mange from sows to their offspring by injection of ivermectin. Effects on swine production

A blind and controlled field study was conducted on a pig farm in Australia to evaluate the activity of 1% ivermectin solution when injected into pregnant sows that were naturally infested with mites. The study was designed to appreciate the tolerance of the product on sows (litter size, litter birth weights, litter weaning weights, pre-weaning mortality) and to show the effects of sarcoptic mange on the growth performances of their offspring. Twenty sows were selected and ranked on Day-10, prior to the start of the study, on the basis of positive mite counts and parity. Sows were randomly allocated into two groups, A and B. On Day-7, they were injected once with product A (1 ml/33 kg; yielding 300 microg ivermectin/kg BW) or product B (placebo), respectively and then moved to the farrowing unit. Mite counts, ear and body lesions were scored and recorded. The average daily weight gain (ADG) was calculated on piglets from birth to Day-45 (ADG(45)) and birth to Day-70 (ADG(70)). Ivermectin was 100% efficient in preventing the transmission of scabies mites and did not have negative effect on the pregnant sows. Growth performances (ADG(45) and ADG(70)) of piglets from treated sows were significantly higher (452 and 541.5 g per day) than that from untreated sows (433.5 and 518.4 g per day) respectively, confirming that sarcoptic mange is detrimental to the production performances of growing pigs.

Leishmania pifanoi pathogenesis: selective lack of a local cutaneous response in the absence of circulating antibody

Recently, a role for B cells in the pathogenesis associated with infection by Leishmania (Leishmania mexicana complex and L. donovani) has been established. In the case of L. mexicana complex parasites (L. mexicana, L. pifanoi, and L. amazonensis), a critical role for immunoglobulin G-mediated mechanisms for the amastigote stage in the host is evident; however, the immunological mechanisms involved remain to be established. In vitro analysis of the kinetics of parasite uptake by macrophages failed to indicate a major effect of antibody opsonization. Given the importance of CD4(+) T cells in the development of disease caused by these parasites, the possibility that the lack of pathogenesis was due to the lack of development of an immune response at the local site (draining lymph node and/or cutaneous site) was explored. Interestingly, the level of CD4(+)-T-cell activation (proliferation and cytokine) in draining lymph nodes from mice lacking circulating antibody (resistant) was found to be comparable to that in nodes from wild-type mice (susceptible) at 2, 5, and 10 weeks postinfection. However, antibody-deficient animals had markedly reduced numbers of monocytes and lymphocytes recruited or retained at the site of cutaneous infection in comparison to wild-type mice, indicating a selective impairment in the local cutaneous immune response. In vitro antigen presentation studies employing tissue-derived (opsonized) amastigotes demonstrated that L. pifanoi-infected FcR(-/-) macrophages, in contrast to comparably infected wild-type cells, failed to activate Leishmania antigen-specific T lymphocytes. These data, taken together, suggest that one possible mechanism for the role of antibody in pathogenesis may be to mediate parasite uptake and regulate the immune response at the local cutaneous site of infection.

Real-time PCR for detection and quantitation of leishmania in mouse tissues

Leishmania spp. are intracellular protozoan parasites that cause a wide spectrum of diseases in humans and dogs worldwide. However, monitoring of the Leishmania burden in its different hosts is still based on cumbersome and poorly sensitive methods. Here we have developed a highly accurate real-time PCR assay with which to reproducibly detect and quantify the relative Leishmania major burden in mouse tissue samples. The assay is performed with the LightCycler system using SYBR Green I and primers amplifying a ca. 120-bp fragment from minicircles of the kinetoplast DNA (kDNA). The assay was able to detect as little as 100 fg of L. major DNA per reaction, which is equivalent to 0.1 parasite. The standard curve designed for quantitation of parasites showed linearity over an at least 6-log DNA concentration range, corresponding to 0.1 to 10(4) parasites per reaction, with a correlation coefficient of 0.979. The assay also proved to have a detection range of the same magnitude as that used for detection of L. donovani and L. amazonensis, but it was 100-fold less sensitive for L. mexicana. When applied to tissues from experimentally infected mice, the real-time PCR assay is not only as sensitive as a conventional PCR assay for detection of Leishmania kDNA but also more rapid. Results indicate that this assay is compatible with the clinical diagnosis of leishmaniasis and will be a great help to scientists who use animals to monitor the efficacy of antileishmanial drugs or vaccines or decipher the unique properties of the life cycle of Leishmania spp.

The ecology of cutaneous leishmaniasis in Nizzana, Israel: infection patterns in the reservoir host, and epidemiological implications

We conducted an extensive interdisciplinary study in an emerging focus of cutaneous leishmaniasis in the Western Negev Desert of Israel between July 1998 and February 2000. The aims of the this study were to determine (1) the reservoir hosts, (2) the distribution of the pathogen within the host range, (3) the associations of host, vector, and pathogen within defined habitats, (4) the demographic distribution of the pathogen within the host populations, and (5) to apply the newly acquired epizootiological data to explain morbidity patterns in humans. Fourteen square (60 m width) sampling plots were delimited in three types of habitats each with a different kind of substrate: loess, sand, and sand-loess ecotone. Rodents and sand flies were trapped and several environmental variables were measured. Leishmania infections in rodents were detected microscopically in stained smears of ear tissue and by a Leishmania-specific polymerase chain reaction. Results indicate that, contrary to previous reports, Psammomys obesus and not Meriones crassus is the main reservoir host in the region. Additional rodents (12 Gerbillus dasyurus and two M. crassus) were also found positive for Leishmania DNA. Prevalence of Leishmania infections amongst P. obesus was highest in loess habitats (65%), intermediate in the sandy-loess ecotone (20%), and 0% in the sandy habitats. Psammomys obesus individuals in the loess habitat of the Nizzana ruins were larger, on average (probably older), than those in the sandy habitat of the Mt. Keren junction. Sand fly density was positively correlated to soil moisture being higher in the relatively humid plots of Nizzana ruins and much lower in the drier sandy soil of Mt. Keren. Elucidation of fundamental ecological factors affecting this disease has helped explain an apparent discrepancy between the distribution of the disease in the zoonotic system and among humans.

Short report: study on the efficacy of a new long-acting formulation of N, N-diethyl-m-toluamide (DEET) for the prevention of tick attachment

The beneficial effects of N, N-diethyl-m-toluamide (DEET) against biting insects of human and animals appear to last <6 hr after a single application to the skin. To prolong the repellent effects of DEET, recently we developed a new long-acting formulation of DEET called LIPODEET. This preparation was retained in the skin for a longer duration of time with minimal systemic absorption. In this study, we have evaluated the protective effect of three compounds (DEET, LIPODEET, and Morpel 220) against attachment of two species of ticks (Amblyomma americanum and Dermacentor variabilis) to rabbit ears. Results show that LIPODEET and Morpel 220 were highly effective in preventing tick attachment to the skin for a longer duration of time (up to 72 hr) than DEET after a single application. Moreover, LIPODEET was found to be acaricidal to both the species of ticks.

Neonatal myiasis: a case report and a role of the Internet

Maggot infestation (myiasis) can occur in the newborn baby. However, neonatal myiasis is rare, and there is no published literature on this subject. Rapid useful information on such an esoteric clinical case can be obtained by searching the Internet. Effective medical management includes complete removal of the maggots and offering reassurance to the distraught parents.

Inter- and intra-specific variation within the genus Psoroptes (Acari: Psoroptidae)

In this paper the taxonomy and relative importance of various species within the genus Psoroptes are reviewed with respect to inter- and intra-specific variations in cross infestivity and host specificity, site of infestation and morphological characters. Intra-specific variation within populations of the sheep scab mite, Psoroptes ovis will then be discussed critically with respect to virulence (the relative growth of the scab lesion and mite burdens), epidemiology, susceptibility to the systemic acaricide, ivermectin, and resistance to synthetic pyrethroid and organophosphate acaricides. Finally, it is suggested that the ear mite, P. cuniculi, and the sheep scab mite, P. ovis are variants of the same species. Information was collected from published literature and from the results of unpublished studies carried out at the VLA, Weybridge over the last 10 years.

Development of a natural model of cutaneous leishmaniasis: powerful effects of vector saliva and saliva preexposure on the long-term outcome of Leishmania major infection in the mouse ear dermis

We have developed a model of cutaneous leishmaniasis due to Leishmania major that seeks to mimic the natural conditions of infection. 1,000 metacyclic promastigotes were coinoculated with a salivary gland sonicate (SGS) obtained from a natural vector, Phlebotomus papatasii, into the ear dermis of naive mice or of mice preexposed to SGS. The studies reveal a dramatic exacerbating effect of SGS on lesion development in the dermal site, and a complete abrogation of this effect in mice preexposed to salivary components. In both BALB/c and C57Bl/6 (B/6) mice, the dermal lesions appeared earlier, were more destructive, and contained greater numbers of parasites after infection in the presence of SGS. Furthermore, coinoculation of SGS converted B/6 mice into a nonhealing phenotype. No effect of SGS was seen in either IL-4- deficient or in SCID mice. Disease exacerbation in both BALB/c and B/6 mice was associated with an early (6 h) increase in the frequency of epidermal cells producing type 2 cytokines. SGS did not elicit type 2 cytokines in the epidermis of mice previously injected with SGS. These mice made antisaliva antibodies that were able to neutralize the ability of SGS to enhance infection and to elicit IL-4 and IL-5 responses in the epidermis. These results are the first to suggest that for individuals at risk of vector-borne infections, history of exposure to vector saliva might influence the outcome of exposure to transmitted parasites.

Evaluation of the prevalence of sarcoptic mange in slaughtered fattening pigs in southeastern Spain

In this study the prevalence of sarcoptic mange in fattening pigs in Murcia, southeastern Spain was investigated. Results showed that 37% of the 1318 slaughtered pigs examined were positive for Sarcoptes scabiei var. suis. Skin lesions potentially attributable to this mite were present in 92.80% of animals, but the parasite could be detected in only 38.60% of them. The condition of the ear (clean/dirty) was not a defining characteristic for the diagnosis of this swine disease. A sucrose flotation-concentration technique was more effective than direct microscopy in finding the mite in ear scrapings.

Efficacy of some pyrethroids against a strain of the rabbit ear mite (Psoroptes cuniculi): an unusual cross-resistance pattern

An in vitro immersion bioassay was used to compare the efficacy of selected pyrethroids against a deltamethrin-resistant strain of rabbit ear mite (Psoroptes cuniculi). A lack of cross-resistance between bromo (deltamethrin) and chloro analogues (cypermethrin) of alpha-cyano-3-phenoxybenzyl-dihalovinyl-dimethylcyclopropane carboxylate was detected. Whereas deltamethrin proved to be inactive (48-h mortality 21.9% at 1000 mg/kg), each cypermethrin isomer mixture tested, including alpha-cypermethrin [IR(cis) alpha S + 1 S (cis) alpha R] and theta-cypermethrin [1R(trans) alpha S + 1 S (trans) alpha R] and their mixture at a ratio of 4/6, beta-cypermethrin, showed high efficiency (48-h mortality > or = 95% at 1000 mg/kg).

Psammomys obesus Cretzschmar, 1828 and zoonotic cutaneous leishmaniasis in Sinai Peninsula, Egypt

In the Middle East, the fat sand rat Psammomys obesus is the most important reservoir host of zoonotic cutaneous leishmamiasis (ZCL). It is the most incriminated host in outbreaks. Two P. obesus caught in Wadi El Gedeiret (Al Arish, North Sinai) were found naturally infected with Leishmania major as indicated by enzyme electrophoresis. In Egypt, the already known reservoir hosts are Gerbillus pyramidum I. Geoffroy St. Hilaire, 1825; Meriones crassus Sundevall, 1984 and Meriones sacramenti Thomas, 1922. The hostal role of P. obesus was discussed.

Epidemiology of subclinical ovine psoroptic otoacariasis in Great Britain

Seven sheep flocks with subclinical psoroptic otoacariasis were investigated. Psoroptes species mites were isolated from 3.1 per cent of the 2676 sheep examined and the prevalence in the flocks ranged between 1.3 and 23.9 per cent, with the highest infestations in pedigree flocks. Unilateral or bilateral infestations were found in sheep of all ages. Adult and shearling rams, with prevalences of 21.5 and 14.2 per cent, respectively, were the most affected and two lambs, two and eight days old, were the youngest to be infested. There was no evidence of vertical transmission. The infestation affected several breeds of sheep. No other known hosts for Psoroptes species present on the premises were shown to be infested. Non-parasitic for-age mites were also isolated from the ear canals of the sheep and may have contributed to the clinical signs which, in adult sheep, ranged from aural haematomas/fibrosis (cauliflower ears), and violent head shaking and ear rubbing leading to excoriation and wounding of the ear and base of the ear. The signs in lambs included plaques of scab (often bloody) on the external ear cleft, excoriation of the base of the ear, ear scratching with the hind feet and inflammation of the external aspects of the horizontal canal. In all cases the internal pinnae were clear of typical psoroptic scabs. Psoroptes mites were isolated from 28.6 per cent of the damaged ears and from 7.8 per cent of the undamaged ears. There was no evidence of classical sheep scab in any of the flocks. Plunge dipping in diazinon, propetamphos or flumethrin, or the use of synthetic pyrethroid pour-on preparations and an oral drench of ivermectin had little effect because ear mite infestations were detected in the flocks after these treatments. An injection of ivermectin at 200 micrograms/kg bodyweight effectively eradicated the infestations when it was administered to these infested flocks.

Effect of ivermectin on the ear mange mite, Psoroptes cuniculi, of rabbits

Rabbits, naturally infected with ear mange mite, Psoroptes cuniculi, were injected subcutaneously with a single dose of ivermectin at 200 micrograms or 400 micrograms/kg of body weight. The effect of the drug was evaluated clinically and parasitologically over 4 weeks. The animals in both groups became negative for mites 6 days after treatment and remained so until the end of trial. The ear lesions disappeared in both groups. However, the regression of lesions was faster in rabbits administered 400 micrograms/kg of ivermectin.

Further studies on the resistance to Onchocerca microfilariae in CBA mice

Various factors governing resistance to the microfilariae (mf) of Onchocerca lienalis in mice have been examined to provide baseline data for use of this model in immunological studies. The survival of mf during a primary infection followed a similar course in the skin from most anatomical regions of the body. Mice were highly resistant to secondary infections, manifested by parasite densities over the body that were reduced by 83-100% compared with controls. Recoveries of mf from the ears, used in later experiments, were a representative measure of parasite survival in other skin sites. The resistance to challenge induced by a primary infection was not dependent on the route of administration (intravenous, intraperitoneal, subcutaneous and intramuscular) of the latter and was apparently systemic. Primary infections of various durations that were chemically-abbreviated conferred maximum protection when of 15 days or longer (95-97%) and substantial resistance when of only 7 days (84%). Similar levels of protection were demonstrated in mice that were sensitized with single or multiply-divided mf doses, or challenged in a similar manner. Primary infections containing as few as 20 mf induced almost the same degree of protection (80%) as 50 to 10,000 mf (88-97%). Apparently, resistance to re-exposure with O. lienalis mf is mediated by a highly effective mechanism(s) in CBA mice.

Life span and distribution of Onchocerca volvulus microfilariae in mice

Microfilariae of Onchocerca volvulus obtained from onchocercomas were inoculated subcutaneously into the inguinal region of mice. Microfilariae disseminated rapidly, invading the tail and lungs within 1 hr and the ears within 3 hr postinoculation. During the early period of infection microfilariae appeared in the eyes, ears, viscera, pelt, carcass, and tail; later, the microfilariae tended to accumulate in the tail. Liver microfilariae were recovered up to 12 wk postinoculation. Intraperitoneal inoculation and subcutaneous inoculation into the inguinal region resulted in the concentration of microfilariae in the tail, whereas inoculation into the scalp caused microfilarial accumulation in the ears.

The german cockroach, Blatella germanica L, from the human ear

A case of invasion of the human ear by the German cockroach Blattella germanica (L) IN Mash'had, Khorassan, Iran is described. As far as the Author is aware this is the first such case recorded and published from Iran.