Showing papers on "Babesia published in 1987"

Seasonal variation of transmission risk of lyme disease and human babesiosis

Abstract: The seasonal host-seeking pattern of nymphal Ixodes dammini infected with Babesia microti or Borrelia burgdorferi was determined on Nantucket Island, Massachusetts, during 1985. The peak period of host-seeking by infected nymphal I. dammini occurred in May and June. On a per person-hour basis, the number of infected ticks collected reached a maximum in May (Babesia = 17.3; Borrelia = 16.2). The number of infected ticks remained high in June, but decreased notably in July, August, and September. Transmission risk of the tick-borne etiologic agents of Lyme disease and human babesiosis in Massachusetts is greatest during the late spring-early summer months of May and June.

Absence of spirochaetes (Borrelia burgdorferi) and piroplasms (Babesia microti) in deer ticks (Ixodes dammini) parasitized by chalcid wasps (Hunterellus hookeri).

Abstract: An entomophagous wasp (Hunterellus hookeri Howard) parasitizes about a third of the host-seeking nymphal Ixodes dammini Spielman et al. ticks on Naushon Island in Massachusetts (U.S.A.) where the agents of Lyme disease (Borrelia burgdorferi Johnson et al.) and human babesiosis (Babesia microti Franca) are enzootic. Following blood-feeding, wasp-parasitized ticks are destroyed by the developing wasp. The prevalence of either human pathogen in host-seeking ticks collected in wasp-infested sites is nearly 40% lower than that found in other sites. Nymphal ticks, collected early in their season of activity, are more frequently parasitized by the wasp and less frequently by the Lyme disease spirochaete than those collected later in the summer. Spirochaetes never infected wasp-infected ticks, and few wasp-infected ticks were concurrently infected by the Babesia piroplasm. Taken together, these correlations indicate that the wasp may render the tick inhospitable to both pathogens. The presence of the wasp may have reduced risk of human infection on the island by either pathogen by as much as a third.

Simultaneous transmission of Borrelia burgdorferi and Babesia microti by individual nymphal Ixodes dammini ticks.

Abstract: Nymphal Ixodes dammini ticks, selected from a group of ticks in which 22 of 31 (71%) contained dual Borrelia burgdorferi and Babesia microti infections, simultaneously transmitted B. burgdorferi and B. microti to 4 of 7 (57%) hamsters exposed to individual ticks.

Protection of Babesia bigemina-immune animals against subsequent challenge with virulent Babesia bovis.

Abstract: Two groups of cattle, one previously exposed to Babesia bigemina and one not, were challenged with Babesia bovis. The group previously infected with Babesia bigemina was only mildly affected upon challenge with B. bovis, whereas four of five of the other group were severely affected. Immunoblotting studies performed in both homologous and heterologous systems showed that there were polypeptides of similar molecular weight in both species, but species-specific polypeptides were demonstrated only in B. bovis by the homologous B. bovis reaction. B. bovis antisera reacted avidly with B. bigemina-infected erythrocytes in fluorescent-antibody assays. In contrast, B. bigemina antisera did not cross-react with B. bovis-infected erythrocytes. Two groups of splenectomized calves were immunized with an enriched antigen fraction of B. bigemina. A third group was immunized by infection with B. bigemina and treatment with a drug. One of the groups of calves immunized with the antigenic fraction of B. bigemina, the group immunized by infection with B. bigemina, and a control group were challenged with B. bovis. All control calves died, whereas 50% of the calves immunized by infection with B. bigemina and 75% of the animals immunized with the B. bigemina antigen survived. The second group immunized with the B. bigemina antigen and a control group were challenged with B. bigemina. All control animals died by day 6, whereas 50% of the vaccinates survived, the deaths occurring on days 8 and 11. The nature of the probable protective mechanism is discussed.

Antigenic relationship between Plasmodium falciparum and Babesia bovis: reactivity with antibodies to culture-derived soluble exoantigens.

Abstract: Antigenic similarities between Plasmodium and Babesia parasites of the phylum Apicomplexa have been previously demonstrated primarily by the serological cross reactivity observed in the indirect fluorescent antibody (IFA) test. We have now studied the antigenic relationship between the human malaria parasite, Plasmodium falciparum, and the hemoparasitic agent of cattle, Babesia bovis, using rabbit monospecific antibodies produced against individual culture-derived P. falciparum polypeptides and bovine polyspecific antibodies to B. bovis exoantigens. These respective antibodies were found to be distinctly cross reactive in the IFA test using infected erythrocytes (squirrel monkey--P. falciparum; bovine--B. bovis) as antigen substrates. Immunofluorescence was shown to be highly specific for parasite surfaces. Additionally, the degree of reactivity with soluble exoantigens contained in Plasmodium and Babesia culture supernatants was monitored by a two-site enzyme immunoassay employing the cross-reactive antibodies. Further evidence for antigenic cross reactivity between P. falciparum and B. bovis parasites was shown with the in vitro inhibition assay. Antibodies to P. falciparum and B. bovis were found to be highly inhibitory for the in vitro growth of P. falciparum in human erythrocytes.

Age distribution of naturally occurring acute babesiosis in cattle in Sweden.

Abstract: The age distribution of clinical cases of babesiosis reported by local veterinary practitioners was investigated in 1976 and 1981. The first study was based on material collected primarily for identifying the Babesia species, the second on computerized reports from a part of one county in Sweden. The results were similar. Most diseased animals, 135/165 (82%) and 145/161 (90%) respectively, were more than 2.5 years old (cows), while 27/165 (169b) and 12/161 (8%) respectively, were 1–2.5 years old and only 3–4 (2–3%) animals were calves less than 1 year old. This age group, however, probably did not meet the same infection risk as did older animals. Among cows (>2.5 years old) there seemed to be no influence of age on the distribution of clinical babesiosis. Calculation based upon the entire animal population of the county investigated in 1981 revealed that clinical babesiosis was reported about 11 times more often among cows than among heifers and steers. The comparatively high resistance among 1–2.5 year–old cattle may be a function of an inverse age resistance, and/or may be influenced by vaccination against babesiosis on »high risk« farms in Sweden and a lower risk of infection on other farms such that animals tend to escape infection prior to adultness. Babesia organisms were found in 156 of 165 cases (95%) reported as clinical babesiosis.

Detection of culture-derived Babesia bovis exoantigen using a two-site enzyme immunoassay.

Abstract: Soluble exoantigens in the supernatants of Babesia bovis cultures have been shown to be efficient immunogens against bovine babesiosis. We used a two-site enzyme immunoassay to monitor the release of these antigens during in vitro cultivation. Bovine immunoglobulin G was isolated from serum of an adult cow previously immunized with culture-derived B. bovis exoantigens and challenged via needle with virulent parasites. The specific immunoglobulin G was used as a capture antibody and as an enzyme-conjugated recognizing antibody. The optimal protein concentration of capture antibody was 10 micrograms/ml. The 24-h cultures showed the greatest antigen concentration. The test was sensitive for detection of differences in species-specific antigenic activity among B. bovis isolates, for determining loss of antigenicity during storage and formalinization, and for monitoring the kinetics of exoantigen release during in vitro cultivation. Antigens cross-reactive with the other major Babesia species of cattle, Babesia bigemina, were also detected with this assay. The high specificity, sensitivity, and reproducibility of this technique should facilitate detection and quantitation of Babesia antigens during purification and in standardization of candidate immunogens.

An outbreak of babesiosis (B. divergens) in a dairy herd comprising different age groups of cattle.

Abstract: Outbreaks of acute bovine babesiosis affecting several individuals within a herd are well known among veterinary practitioners and farmers within different parts of Sweden. Although outbreaks may not occur every year, they are feared by the farmers due to the unpredictability of the disease, its suddeness of onset, its rapid course, and the high mortality unless treated. Sporadic outbreaks of acute bovine babesiosis comprising several animals within a limited time period have been previously reported in Sweden (Linnaeus 1747, Bergman & Waxberg 1915, Heijbel 1928), in Finland (Hinderson 1928), in Norway as cited by Tambs-Lyche (1943), in the United Kingdom (Donnelly et al. 1970) and elsewhere within the area where B. divergens is distributed (Tambs-Lyche 1943, Purnell 1980). In all of these cases groups of animals had been transferred onto pastures where clinical cases of bovine babesiosis were known to occur from areas where the disease was rare or had never occurred; i.e. unexposed animals were transferred onto pastures with Babesia infected ticks. The farmers first became aware of this situation after the outbreak had occurred.

Protozoan parasites of British small rodents

Abstract: Thirty-five species of protozoan parasites belonging to thirteen genera have now been recorded for British small rodents. These include species of Entamoeba, Giardia, Spironucleus, Trichomonas, Chilomastix, Eimeria and Cryptosporidium in the gut; Trypanosoma, Hepatozoon and Babesia in the blood; and Toxoplasma, Frenkelia and Sarcocystis in the tissues. Recent advances have progressed along two lines, the elucidation of the life-cycles of the species ofFrenkelia and Sarcocystis, which are now known to involve a carnivore as the final host, and laboratory studies on those parasites that can be maintained in laboratory animals. It is now possible to draw up a definitive list of hosts and parasites and this should serve as a basis for studies on the epidemiology of these parasites and their possible effects on their hosts.