A large-scale field randomized trial demonstrates safety and efficacy of the vaccine LetiFend® against canine leishmaniosis.

Canine leishmaniosis is a zoonotic disease caused by Leishmania infantum. Extensive research is currently ongoing to develop safe and effective vaccines to protect from disease development. The European Commission has granted a marketing authorization for LetiFend®, a new vaccine containing recombinant Protein Q. The efficacy of LetiFend® vaccination in a large-scale dog population of both sexes, different breeds and ages in endemic areas is reported in this multicenter, randomized, double-blind, placebo-controlled field trial. Dogs (n = 549) living in France and Spain were randomly selected to receive a single subcutaneous dose of LetiFend® or placebo per year, and were naturally exposed to two L. infantum transmission seasons. Clinical examinations, blood and lymphoid organ sampling to evaluate serological, parasitological and disease status of the dogs were performed at different time points during the study. LetiFend® was very well tolerated and clearly reduced the incidence of clinical signs related to leishmaniosis. The number of confirmed cases of leishmaniosis was statistically significantly lower in the vaccine group. The number of dogs with parasites was close to be significantly reduced in the vaccine group (p = 0.0564). Re-vaccination of seropositive dogs demonstrated to be safe and not to worsen the course of the disease. The likelihood that a dog vaccinated with LetiFend® develops a confirmed case or clinical signs of leishmaniosis in areas with high pressure is, respectively, 5 and 9.8 time less than that for an unvaccinated dog. Thus, the overall efficacy of the LetiFend® vaccine in the prevention of confirmed cases of leishmaniosis in endemic areas with high disease pressure was shown to be 72%. In conclusion, this field trial demonstrates that LetiFend® is a novel, safe and effective vaccine for the active immunization of non-infected dogs from 6 months of age in reducing the risk of developing clinical leishmaniosis after natural infection with Leishmania infantum.

In vivo and in vitro sensitization to domestic mites in German urban and rural allergic patients.

Sensitization to domestic mites is common in Germany. The main objectives of this study were (1) to establish the rate of skin test sensitivity to Dermatophagoides pteronyssinus, Acarus siro, Lepidoglyphus destructor, and Tyrophagus putrescentiae in 512 consecutive patients evaluated for upper and/or lower respiratory complaints; (2) to verify how many of the patients with a positive skin test to at least one of the three storage mites were also skin test positive to D. pteronyssinus; and (3) to verify how many of the patients with at least one positive skin test to one of the storage mites previously mentioned were also sensitized, in vitro, to other mite species. A total of 512 consecutive patients with rhinitis and/or asthma, living in urban or rural areas of central Germany were skin tested with extracts of D. pteronyssinus, A. siro, L. destructor, and T. putrescentiae. In addition, specific IgE determinations to Euroglyphus maynei, Blomia tropicalis, Blomia tjibodas, Blomia kulagini, and Gohieria fusca were conducted in those individuals with a positive skin test to at least one of the storage mites used in skin testing. Of the 512 patients, 103 (20.1%; 77 urban dwellers and 26 farmers) reacted to at least one of the storage mites. From this latter group, 88 individuals (85.4%) also skin tested positive to D. pteronyssinus. In vitro specific IgE determinations revealed a high rate of sensitization to the other mite species studied. We conclude that sensitization to storage mites in Germany is frequently associated with sensitivity to D. pteronyssinus. Overall, skin test sensitivity to storage mites was greater in rural than in city dwellers. In vitro sensitization to B. tjibodas was also significantly greater in rural than in city dwellers.

Conjunctival provocation tests in the diagnosis of Anisakis simplex hypersensitivity.

INTRODUCTION: The prevalence of positive skin tests to Anisakis simplex is high compared with the low incidence of true gastroallergic Anisakiasis. There is little information about the prevalence of positive conjunctival tests in A. simplex-sensitized individuals. This study assesses the predictive value of conjunctival provocation test in two groups of A. simplex-sensitized subjects and negative controls. METHODS: Group A consisted of 28 individuals with a clinical history strongly suggestive of gastroallergic anisakiasis and group B, of 32 individuals without such history. The 60 individuals had positive skin tests and in vitro specific IgE determinations to A. simplex. Skin and conjunctival provocation tests were performed with an extract of A. simplex at a concentration of 1 mg of lyophilized material per ml. RESULTS: Conjunctival provocation tests were positive in 21/28 (75%) of group A patients and in 10/32 (31%) of group B patients. This difference was statistically significant (p < 0.015); the odds ratio was 6.6 (2.11-20.5; p < 0.05). The diagnostic value of the conjunctival provocation test was expressed by the following statistical indicators: sensitivity 75% (55.8%-88.6%), false positive 25% (11.4%-45.2%), specificity 68.7% (49.9%-83.2%), false negative 31.2% (16.7%-50%), positive predictive value 67.7% (48.5%-82.7%), negative predictive value 75.9% (56.1%-89%), Yuden index 1.43. There were no statistical differences related to age, sex, or atopic status in patients with a positive or negative conjunctival challenge. Total and specific IgE levels to A. simplex were significantly greater (p < 0.05 and p < 0.001, respectively) in the group of patients with a positive challenge. CONCLUSIONS: The results demonstrate that positive conjunctival provocation tests and high specific and total IgE levels are more prevalent in patients with a clinical history strongly suggestive of gastroallergic anisakiasis. Despite the significant differences obtained in both groups, this test has a limited diagnostic value to clinically discriminate patients with a history consistent with gastroallergic anisakiasis.