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Biomedical subjects

Y Rechav

Publications and source records attributed to Y Rechav.

At least 55 records · Page 3Linked to original sources
PubMed1987

Development of resistance in rabbits to immature stages of the Ixodid tick Rhipicephalus appendiculatus.

A study of acquired resistance in rabbits to larvae and nymphs of Rhipicephalus appendiculatus Neumann showed a positive correlation between the levels of gamma globulin in the serum and the resistance developed by the host. A negative correlation between the weight of engorged ticks and gamma globulin levels was also demonstrated during this study. Repeated infestations with ticks evoked a typical antibody response to antigenic challenge. The levels of gamma globulin stabilized after three infestations and no further decrease in the weight of ticks was observed. The mechanism of the acquisition of resistance by the rabbits, the production of antibodies and the involvement of complement are discussed.

Animals↗
PubMed1987

The ecology of the African vectors of heartwater, with particular reference to Amblyomma hebraeum and Amblyomma variegatum.

The hosts, sites of attachment, life cycle, habitat requirements and seasonal abundance of Amblyomma astrion, Amblyomma cohaerens, Amblyomma gemma, Amblyomma hebraeum, Amblyomma lepidum, Amblyomma marmoreum, Amblyomma pomposum, Amblyomma sparsum, Amblyomma tholloni and Amblyomma variegatum, the 10 potential vectors of heartwater in Africa, are listed. Factors influencing the distribution and abundance of the ticks as well as interactions with other species and the role of predators and pathogens are discussed.

Animals↗
PubMed1986

Seasonal activity and hosts of the vectors of Crimean-Congo haemorrhagic fever in South Africa.

The seasonal activity and hosts of two species of Hyalomma, H. marginatum rufipes and H. truncatum, were studied in a Crimean-Congo haemorrhagic fever (CCHF) zone near Bloemhof in the western Transvaal. The study was conducted at the S.A. Lombard Nature Reserve, where a child had died from this disease. It was found that adults of the two species are very common during summer while the immature stages were active during winter and also demonstrated a second peak of activity in November. H. marginatum rufipes adults fed mainly on eland and zebra, while H. truncatum preferred black wildebeest, springbok and blesbok as hosts. Immature specimens of H. truncatum fed on hares and rodents and those of H. marginatum rufipes on hares, rodents and guinea-fowl. It appears that the immature stages pick up the virus from hares and other small mammals, but it is the adult ticks who transfer the virus to man. The epidemiology of tick-borne CCHF is discussed.

Animals↗
PubMed1983

A bioassay technique for the pheromone emitted by Amblyomma hebraeum males.

Attachment of Amblyomma hebraeum females, either around feeding males or in areas in which extracts of fed males had previously been placed, was studied. The percentage attachment of female ticks around feeding males was significantly higher than that inside extract-treated areas. It was also found that the percentage attachment around the males increases with time, but there is little or no increase in attachment with time inside the treated areas. The amount of pheromone released by 1 feeding male was enough to stimulate attachment of females, although the rate of attachment accelerated as the number of males increased.

Animals↗
PubMed1981

Life cycle in the laboratory and seasonal activity of the tick Rhipicephalus glabroscutatum (Acarina: Ixodidae).

The life cycle of Rhipicephalus glabroscutatum Du Toit was studied under laboratory conditions at 26 C +/- 1C. The preoviposition period was 6.0 +/- 0.12 days. The mean number of eggs was 2,044 +/- 186 (maximum 3,053, minimum 748), and the greatest production was recorded on day 3 (234 eggs/female). The incubation period was 37.4 +/- 0.32 days (maximum 41, minimum 35). The feeding time of larvae and nymphs of this two-host tick was 20.2 +/- 0.33 days (16-28). Nymphs producing males weighed less (4.09 +/- 0.07 mg) than those producing females (6.62 +/- 0.08 mg). The combined larval-nymphal feeding time of the former was shorter (19.3 +/- 0.90 days) than that of the latter (20.4 +/- 0.90 days). The molting period of nymphs to adults of both sexes was similar. Engorged females weighed (mean +/- SE) 204.0 +/- 10.75 mg and the feeding time was 7.9 +/- 0.34 days. Spermatogenesis was completed on day 5 after the commencement of feeding, and pairing between males and females and mating occurred subsequently. The adult ticks were active during early summer and were much more prevalent on kudu than on angora goats and cattle. Immature stages were not found during this study.

Animals↗
PubMed1978

The life cycle of the tick Hyalomma marginatum rufipes Koch (Acarina: Ixodidae) under laboratory conditions.

The life cycle of Hyalomma marginatum rufipes Koch was studied under laboratory conditions at 26 +/- 1 C. The preoviposition period was 7.1 +/- 0.23 days. The mean (+/- SE) number of eggs was 6,867 +/- 2,609 (max. 13,180, min. 3,184). The greatest egg production was recorded on day 3 (avg 1,170 egg/female). The incubation period was 29.3 +/- 2.96 days. The feeding time of larvae and nymphs of this 2-host tick was 22.8 +/- 0.13 days. Nymphs producing males weighed less (23.1 +/- 0.748 mg) than those producing females (26.8 +/- 1.19 mg); the combined larval-nymphal feeding time of the former was shorter (21.9 +/- 0.1 days) than that of the latter (22.9 +/- 1.12 days). The premolting period of nymphs to adults of both sexes was similar.

Animals↗