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Biomedical subjects

R J Tatchell

Publications and source records attributed to R J Tatchell.

18 recordsLinked to original sources
PubMed1997

Sheep and goat tick management.

Tick and tick-borne disease (TBD) problems of sheep and goats are less well studied than those of cattle. Nevertheless, small ruminants are able to acquire worthwhile resistance to most tick species and the principles of enzootic stability and the need to preserve it are similar to those with cattle. In practice, sheep and goats are often grazed nomadically and initial TBD infections may be delayed. This may well account for losses from Nairobi sheep disease and heartwater. Sheep and goats are also affected by direct tick damage including tick bite abscesses, tick paralysis, tick-induced dermatophilosis, etc. Otherwise direct damage is believed to be only slight and stress from dipping causes reductions in liveweight gain greater than those caused by the ticks. Even "pour-on" preparations produce no economic benefit in studied situations despite the lack of stress. A pragmatic approach to tick management is needed for varying situations although the need to preserve enzootic stability is of paramount importance.

Animals↗
PubMed1987

Ticks (Acari:Ixodidae) of the Blue and White Nile ecosystems in the Sudan with particular reference to the Rhipicephalus sanguineus group.

Twenty-four adult ixodid tick species, infesting livestock and some wildlife hosts along the Blue and White Nile in the Sudan, were identified. Three species, Boophilus geigyi, Rhipicephalus camicasi and R. bergeoni, were recorded for the first time from the Sudan. Tick numbers on indigenous breeds of cattle (Bos indicus) were relatively low, ranging between 17.1 and 40.5 per animal. Young cattle grazing with the herd carried significantly fewer ticks than older animals. With the exception of B. annulatus and R. simus, which have extended their distribution further north into Blue Nile, Gezira and Khartoum Provinces, the distribution patterns of the most important cattle ticks have been relatively unchanged over the past 30 years. The Rhicicephalus sanguineus group was represented by six species. R. camicasi was the only species present on cattle, sheep and goats in the north in Kassala and Khartoum Provinces, whereas this species occurred sympatrically with R. guilhoni and R. turanicus further south in Gezira and Blue Nile Provinces. In the Southern Region of the Sudan only R. turanicus and R. guilhoni were present, the latter being by far the predominant species, with peak activity towards the end of the rains in the Jonglei Canal Area. R. bergeoni was collected once, from cattle near the Ethiopian border in Blue Nile Province, whereas R. sanguineus sensu stricto was collected throughout the study area, from domestic dogs only. Finally, R. sulcatus was found once on a hare. The distributions of the common tick species are correlated with the occurrence of tick-borne diseases of domestic animals and recommendations for the control of tick-borne diseases and their vectors in the Sudan are given.

Animals↗
PubMed1986

A study of the justification for intensive tick control in Kenyan rangelands.

Sixty male weaner cattle at the National Range Research Station, Kiboko, Kenya were placed in four groups of 15 animals under four different tick control regimens for 16 months. The treatment groups were: spraying with acaricide weekly, spraying every three weeks, spraying whenever group mean tick infestations reached more than 200 per animal (once only in the course of the study) and a control unsprayed group. The cattle were weighed monthly. There were no significant differences between the liveweight gains of the groups during a period of severe drought and during the following period of compensatory weight gain. The untreated group gained more weight than the other groups. Cattle died in all groups, but without significant differences between the groups; the long drought and associated malnutrition were the prime cause of death. Rhipicephalus pravus and R pulchellus were the dominant tick species with fewer Amblyomma gemma, Hyalomma truncatum and small numbers of Boophilus decoloratus and R evertsi. These ticks transmit anaplasmosis, babesiosis and cowdriosis in the study area. Total tick counts reached 750 on individual animals but group means rarely reached more than 200 because of high resistance to ticks in some animals. Host resistance ranking within groups was virtually constant throughout the experiment. The study showed that intensive tick control is not required in the semi-arid areas of Africa.

Animals↗
PubMed1977

Studies on Theileriidae (Sporozoa) in Tanzania. X. A large-scale field trial on immunization against cattle Theileriosis.

50 cattle immunized by an infection and treatment method with 3 strains of Theileria parva (Mugaga, Kiambu 5 and Serengeti transformed), together with 19 controls, were exposed to natural tick infestation in Tanzania, in a site where a continuous influx of infected ticks from different regions of the country may be expected to occur. Exposure lasted for 2 months, monitoring continued for 3 more weeks after exposure ended. All 19 controls contracted East Coast Fever and died. 40 of the 50 immunized animals survived the whole period of monitoring; the other 10 died of accidents (2), heartwater (3) and unidentified causes (5); none died of ECF. It is recommended that this method of immunization be routinely applied to protect valuable animals at risk. An attempt to immunize against pathogenic Theileria mutans, by injecting blood containing piroplasms of a strain of low pathogenicity, showed that this method may protect against high parasitaemias caused by natural tick-borne infections and may be useful in eliminating the confusing factor of T. mutans in future trials on East Coast Fever.

Animals↗
PubMed1970

Neutrophils: their role in the formation of a tick feeding lesion.

Dogs infested with adtult Rhipicephalus sanguineus were given nitrogen mustard to reduce leukocyte numbers. In the treated animals the tick lesions were insignificant, lacking the collagen destruiction found in untreated hosts, bitt the ticks engorged normally. Feeding results from tick secretions causing vascitlar trauima and is independent of tissute damage associated with inflammatory responses.

Animals↗