The efficacy of a selamectin (Stronghold ®) spot on treatment in the prevention of Bartonella henselae transmission by Ctenocephalides felis in cats, using a new high-challenge model.

Bartonella henselae is the causative agent of cat scratch disease in humans, which is recognized as an emerging zoonotic disease. Ctenocephalides felis is the main vector, and transmission of B. henselae infection between cats and humans occurs mainly through infected flea feces. Control of feline infestation with this arthropod vector therefore provides an important strategy for the prevention of infection of both humans and cats. In the present study, a new challenge model is used to evaluate the efficacy of selamectin (Stronghold(®) spot on) in the prevention of B. henselae transmission by C. felis. In this new challenge model, domestic cats were infected by direct application of B. henselae-positive fleas. The fleas used for infestation were infected by feeding on blood that contained in vitro-cultured B. henselae. The direct application of the fleas to the animals and the use of different B. henselae strains ensured a high and consistent challenge. Two groups of six cats were randomly allocated on pre-treatment flea counts to either control (untreated cats) or the selamectin-treated group with one pipette per cat according to the label instruction. Stronghold (selamectin 6 % spot on solution) was administered on days 0 and 32. On days 3, 10, 19, 25, and 31, each cat was infested by direct application of 20 fleas that fed on blood inoculated with B. henselae. Polymerase chain reaction (PCR) on pooled fleas confirmed that the fleas were infected. Blood samples were collected from each cat on days -3 (prior to flea infestation and treatment), 9, 17, 24, 30, 37, and 44 and assayed for B. henselae antibodies using an indirect immunofluorescence (IFA), for the presence of bacteria by bacterial culture and for B. henselae DNA presence by PCR. Cats were also assessed on a daily basis for general health. There were no abnormal health observations during the study and none of the animals required concomitant treatment. None of the cats displayed any clinical signs of bartonellosis during the study. In the untreated group, all cats became bacteremic within 17 to 44 days. None of the selamectin-treated cats became positive during the study. It was concluded that Stronghold(®) spot on administered to cats was efficacious in the prevention of the transmission of B. henselae by fleas to cats in a high-challenge model.

A flea and tick collar containing 10% imidacloprid and 4.5% flumethrin prevents flea transmission of Bartonella henselae in cats.

BACKGROUND: Bartonella henselae is transmitted amongst cats by Ctenocephalides felis and is associated with multiple clinical syndromes in cats and people. In a previous study, monthly spot-on administration of 10% imidacloprid/1% moxidectin was shown to block transmission of B. henselae amongst cats experimentally exposed to infected C. felis. The purpose of this study was to determine whether application of a flea and tick collar containing 10% imidacloprid and 4.5% flumethrin would lessen C. felis transmission of B. henselae amongst cats for 8 months. METHODS: Specific pathogen free cats (n = 19) were housed in three adjoining enclosures that were separated by mesh to allow C. felis to pass among groups but prevent cats in different enclosures from contacting one another. One group of 4 cats was inoculated intravenously with B. henselae and after infection was confirmed in all cats based on positive PCR assay results, the cats were housed in the middle enclosure. The B. henselae infected cat group was flanked by a group of 8 cats that had the collar placed and maintained for the duration of the study and a group of 7 cats that were not treated. Ctenocephalides felis (50 males and 50 females) raised in an insectary were placed on each of the 4 cats in the B. henselae infected group monthly for 7 applications and then every 2 weeks for 4 applications starting the day the collar was applied. Blood was collected from all cats weekly for Bartonella spp. PCR, serology and culture. RESULTS: While side-effects associated with the collars were not noted, persistent fever necessitating enrofloxacin therapy occurred in two of the untreated cats. While B. henselae infection was ultimately confirmed in 4 of 7 of the untreated cats, none of the cats with collars became infected (P = 0.026). CONCLUSIONS: In this study design, use of a collar containing 10% imidacloprid and 4.5% flumethrin was well tolerated and prevented C. felis transmission of B. henselae amongst cats for 8 months.

Evaluation of topical application of 10% imidacloprid-1% moxidectin to prevent Bartonella henselae transmission from cat fleas.

OBJECTIVE: To determine whether monthly topical administration of a combination of 10% imidacloprid and 1% moxidectin would lessen flea (Ctenocephalides felis) transmission of Bartonella henselae among cats. DESIGN: Controlled trial. ANIMALS: 18 specific pathogen-free cats housed in 3 groups of 6. PROCEDURES: 3 enclosures were separated by mesh to allow fleas to pass among groups yet prevent cats from contacting one another. One group was inoculated IV with B henselae, and after infection was confirmed, the cats were housed in the middle enclosure. This infected group was flanked by a group that was treated topically with 10% imidacloprid-1% moxidectin monthly for 3 months and by an untreated group. On days 0, 15, 28, and 42, 100 fleas/cat were placed on each of the 6 cats in the B henselae-infected group. Blood samples were collected from all cats weekly for detection of Bartonella spp via PCR assay, bacterial culture, and serologic assay. RESULTS: B henselae infection was confirmed in the cats infected IV and in all untreated cats after flea exposure; none of the cats treated with the imidacloprid-moxidectin combination became infected. CONCLUSIONS AND CLINICAL RELEVANCE: In this setting, monthly topical administration of 10% imidacloprid-1% moxidectin reduced flea infestation, compared with infestation in untreated cats, and thus prevented flea transmission of B henselae to treated cats. Regular monthly use of this flea control product in cats may lessen the likelihood of humans acquiring B henselae infection.

Bartonella henselae survives after the storage period of red blood cell units: is it transmissible by transfusion?

Bartonella henselae is the agent of cat scratch disease and bacillary angiomatosis. Blood donors can be asymptomatic carriers of B. henselae and the risk for transmission by transfusion should be considered. The objective of this study was to demonstrate that B. henselae remains viable in red blood cell (RBC) units at the end of the storage period. Two RBC units were split into two portions. One portion was inoculated with B. henselae and the other was used as a control. All units were stored at 4 degrees C for 35 days. Aliquots were collected on a weekly basis for culture in a dish with chocolate agar, ideal for the cultivation of this agent. Samples were collected on days 1 and 35 and taken for culture in Bact/Alert R blood culture bottles. Aliquots taken simultaneously were fixed in Karnovsky's medium for subsequent electron microscopy evaluation. Samples from infected bags successfully isolated B. henselae by chocolate agar culture, although Bact/Alert R blood culture bottles remained negative. Bartonella spp. structures within erythrocytes were confirmed by electron microscopy. The viability of B. henselae was demonstrated after a storage period of RBC units. These data reinforce the possibility of infection by transfusion of blood units collected from asymptomatic blood donors.

Bartonella henselae infection in cats: evaluation during primary infection, treatment, and rechallenge infection.

Bartonella henselae infection was established in eight cats of various ages by experimental inoculation. All cats remained persistently bacteremic until they were treated 4 to 7 weeks after primary inoculation. Antibody titers increased and peaked between 4 and 12 weeks for all cats. Treatment with doxycycline for 1 week was effective in suppressing bacteremia in all cats but was effective in clearing infection from only four cats. Amoxicillin, given subsequently, was effective in clearing the infection from three of the remaining cats. One kitten that remained bacteremic was treated unsuccessfully with enrofloxacin, and its bacteremia was finally cleared when it was treated with a clavulanate-amoxicillin combination. After the bacteremia was cleared, with a corresponding reduction in serum antibody titers, all eight cats were rechallenged with B. henselae. None of the cats became bacteremic after secondary challenge, and all had higher and more rapid increases in serum antibody titers than after primary inoculation. The cats became resistant to reinfection following recovery from infection, indicating that immunoprophylaxis in cats might be beneficial in helping to reduce their public health risk.

Bacillary angiomatosis and bacillary peliosis in patients infected with human immunodeficiency virus: clinical characteristics in a case-control study.

Clinical characteristics associated with bacillary angiomatosis and bacillary peliosis (BAP) in patients with human immunodeficiency virus (HIV) infection were evaluated in a case-control study; 42 case-patients and 84 controls were matched by clinical care institution. Case-patients presented with fever (temperature, > 37.8 degrees C; 93%), a median CD4 lymphocyte count of 21/mm3, cutaneous or subcutaneous vascular lesions (55%), lymphadenopathy (21%), and/or abdominal symptoms (24%). Many case-patients experienced long delays between medical evaluation and diagnosis of BAP (median, 4 weeks; range, 1 day to 24 months). Case-patients were more likely than controls to have fever, lymphadenopathy, hepatomegaly, splenomegaly, a low CD4 lymphocyte count, anemia, or an elevated serum level of alkaline phosphatase (AP) (P < .001). In multivariate analysis, a CD4 lymphocyte count of < 200/mm3 (matched odds ratio [OR], 9.9; P < .09), anemia reflected by a hematocrit value of < 0.36 (OR, 19.7; P < .04), and an elevated AP level of > or = 2.6 mukat/L (OR, 23.9; P < .05) remained associated with disease after therapy with zidovudine was controlled for. BAP should be considered an AIDS-defining opportunistic infection and should be included in the differential diagnosis for febrile, HIV-infected patients with cutaneous or osteolytic lesions, lymphadenopathy, abdominal symptoms, anemia, or an elevated serum level of AP.