Hepatozoon canis: the prevalence of antibodies and gametocytes in dogs in Israel

A survey for the prevalence of antibodies to Hepatozoon canis and for intraneutrophilic H. canis gametocytes in the peripheral blood neutrophils of dogs in Israel showed that 33.1% were seropositive, while only 1% of the dogs sampled had detectable parasites in their blood smears. Exposure to H. canis is widespread but it appears that most infected dogs undergo a subclinical infection and only a small proportion develop clinical disease.

A study of the vaccinal value of various extracts of concealed antigens and salivary gland extracts against Ornithodoros erraticus and Ornithodoros moubata

On pig farms, elimination of the argasid ticks acting as reservoirs and vectors for African swine fever greatly favours the eradication of this disease. The elimination of Ornithodoros erraticus involves many problems, most of which could be easily solved by the development of an anti-O. erraticus vaccine. With a view to developing this vaccine, we have tested the protective value of the immune response induced in swine by seven 'concealed' antigens and one soluble salivary gland extract. The latter extract was also prepared from Ornithodoros moubata specimens and tested against this tick. Our results indicate that the immune response elicited by the concealed antigens has no protective value against O. erraticus. The immune response induced by the salivary gland extracts against adults of O. erraticus and O. moubata was apparent in a reduced ingestion of blood (40-60%; P < 0.01) (except in males of O. erraticus) and in a significant decrease (40-60%; P < 0.01) in fecundity in 100% of the females of both species. The good results obtained with salivary antigens, which in situations of natural contact have no protective value, are attributed to the fact that when these antigens are injected with adjuvants, the immune system recognizes certain salivary components (probably those which enable the parasite to feed) which it does not recognize under natural conditions of exposure.

Risk of infections transmitted by arthropods and rodents in forestry workers

One hundred and fifty-one forestry workers and 151 matched office clerks were compared as to the presence of antibodies against Borelia burgdorferi, tick-borne encephalitis virus, Puumalavirus and lymphocytic choriomeningitis virus. Their occupational risks of being infected by Borrelia was fourfold and significant, by Puumalavirus and lymphocytic choriomeningitis virus was increased but not significant. No seropositivity has been established against tick-borne encephalitis virus.

The major histocompatibility complex-restricted response of recombinant inbred strains of mice to natural tick transmission of Borrelia burgdorferi

The causative agent of Lyme disease, Borrelia burgdorferi, is transmitted by ticks of the Ixodes ricinus complex. In this study, we report the antibody response of recombinant inbred strains of mice of the H-2, b, d, and k haplotypes, infected with B. burgdorferi as a result of exposure to infected I. dammini. The patterns of antibody response assayed by Western blot analysis indicate significant major histocompatibility complex (MHC) restriction to bacterial antigens within the first 2 mo of infection in mice. Other bacterial antigens induce a significant response across the MHC haplotypes tested when assayed on the same bacterial strain used to transmit the infection, but do not crossreact with the same proteins derived from heterologous strains of B. burgdorferi. No response to outer surface protein A was detected at any time during the 60-d period we analyzed this infection. A third group of bacterial antigens appear to generate a MHC-nonrestricted response, and this lack of restriction is maintained when assaying the crossreactivity of the response with other strains of B. burgdorferi. These proteins may provide more accurate diagnostic probes than those currently in use. Finally, there appears to be a significant difference in the expression of most bacterial antigens when the spirochete is cultured for many passages since the same strain of bacterium isolated from low-passage and high-passage preparations exhibit different banding patterns in Western blots when assayed with the same sera.