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D Jefferies

Publications and source records attributed to D Jefferies.

23 records · Page 2Linked to original sources
PubMed1987

Cibarial infections of Trypanosoma vivax and T. congolense in Glossina.

In a percentage of laboratory bred Glossina infected with Trypanosoma congolense or T. vivax, trypanosomes colonized the cibarium as well as the midgut and/or the proboscis. Field-caught tsetse flies also had T. congolense and T. vivax cibarial infections. T. congolense cibarial infections occurred in all species of Glossina examined: G. tachinoides, G. palpalis palpalis, G. morsitans morsitans and G. m. submorsitans. T. vivax was only found in the cibarium of G. tachinoides. Trypanosomes were firmly attached in the cibarium, as shown by scanning electron microscopy. Two field-caught G. tachinoides were also discovered to have only cibarial infections, presumably of T. vivax. More information is required on the occurrence of cibarial infections in Glossina, especially in the field. It is suggested that examination of the cibarium should be carried out as part of the routine dissection of tsetse flies in the field.

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PubMed1987

The effect of trypanocidal drugs on the transmission of Trypanosoma brucei brucei by Glossina morsitans centralis.

The effects of trypanocidal drugs on Trypanosoma b. brucei infections in Glossina m. centralis have been investigated. Pentamidine and suramin exhibited no significant effects but both berenil and samorin reduced the number of salivary gland infections in comparison with controls. Berenil at concentrations of 10, 1.0 and 0.1 microgram/ml significantly reduced the number of mature infections when fed to flies throughout the whole period of trypanosome development. A similar result was obtained with samorin at 0.1 microgram/ml. Subsequent experiments showed that administration of both drugs at an early stage was more effective in preventing the maturation of infection than a later but more prolonged administration. Reported drug levels in the blood of different experimental host animals are of the same magnitude as those used here. It is suggested that repeated feeding of T. b. brucei infected Glossina on drug-treated hosts may reduce transmission, although alternative bloodmeal sources would reduce this effect. These influences are worthy of investigation in the field.

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PubMed1986

Fluid mechanics of bloodmeal uptake by Leishmania-infected sandflies.

The fluid mechanics of blood flow in the pharynx and cibarium of Phlebotomus papatasi are described using a simple static model. The flow is characterized as viscous laminar. The Hagen-Poiseuille equation is used to assess the effects of attached parasites in the foregut of Leishmania-infected sandflies on blood flow. The reductions in flow rate imposed by parasite colonization of the pharynx and cibarium will reduce the ability of an infected fly to take a bloodmeal, thus encouraging further probing, enhancing transmission. Regurgitation of the contents of the foregut is also possible. This will aid the deposition of infective forms from the foregut. Transmission by means of regurgitation of parasites from the midgut is considered unlikely.

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