In the present study, the life cycle of Tunga penetrans was established in Wistar rats in the laboratory, and the morphology of the resulting developmental stages was studied by means of light and scanning electron microscopy. It was seen that the females enter at a nonfertilized stage through the skin of their hosts. Only there the copulation occurs, while females and males brought together in a Petri dish showed no interest in each other. In any way -- fertilized or not -- the females start about 6 days after penetration and hypertrophy with the ejection of eggs. While fertilized eggs proceed to development, the unfertilized ones remain arrested. The eggs are ovoid and measure about 600 x 320 mum. The larvae hatch from the eggs 1-6 days (mean 3-4) after ejection. Formation of larvae 2 took at least another day, while 4 up to 10 days more were needed until this larva starts pupation (mean 5-7 days). The formation of the adult fleas inside the puparium occurred within 9-15 days (with a maximum hatch at day 12). Adult female fleas having reached the skin of a host start blood sucking within 5 min and prepare to enter the skin. After 24 h, the flea stacked already with two thirds of its body inside the skin. After 40 h, the penetration was completed, and feeding and hypertrophical enlargement started, which was completed on day 6, when eggs became ejected. When studying the morphology of the fleas obtained from different hosts, slight variations were seen, which, however, are not significant for a species separation but may be an indication of the presence of different strains/races or the beginning of such a formation.

No abstract

The phylogenetic relationships among 31 different flea isolates representing seven different species were studied by nucleotide sequence comparison of the internal transcribed spacer 1 (ITS1), internal transcribed spacer 2 (ITS2) and/or mitochondrial 16S ribosomal RNA gene (mt16S-rDNA) to examine the patterns of variation. Results show that all regions are useful in discriminating among flea species. In Ctenocephalides felis and Tunga penetrans, some differences in these gene regions occurred among different isolates within the same species. In the latter case, the differences are in the mt16S-rDNA region, with one isolate showing 48% divergence in nucleotide sequence. The taxonomic implications of this result are unclear at present. The gene regions revealed differences between C. felis isolates only after DNA sequencing the PCR products. Further differentiation among C. felis isolates was obtained using four different random binding primers (decamers) and primers for mammalian aldolase to amplify narrow differences in the genome. Using these primers we were able to discriminate between different C. felis isolates and determine that some of the genetic variation coincided with minor differences in response to the control agent imidacloprid. However, overall findings do not support the existence of subspecies of C. felis.

The feline leukemia virus (FeLV) is a naturally occurring and widespread retrovirus among domestic cats. The virus is mainly transmitted horizontally through saliva, blood and other body fluids by close contact between cats. Vectors other than cats, e.g. blood-sucking parasites, have not been reported. This study tested the vector potential of the cat flea ( Ctenocephalides felis) for FeLV. In a first feeding, fleas were fed for 24 h with blood from a FeLV-infected cat with persistent viremia. FeLV could be detected in the fleas, as well as in their feces. Fleas were then divided in two populations and fed in a second feeding for 5 h or 24 h with non-infected non-viremic blood. FeLV was again detected in the fleas and their feces. In addition, the two resulting blood samples of the second feeding were subsequently tested for FeLV and both samples were positive for FeLV RNA. The cat flea transmitted the FeLV from one blood sample to another. In a third feeding, the same populations of fleas were fed again with non-infected blood for 5 h or 24 h. This time FeLV was not detected in the fleas, or in the feces or blood samples. Results show that cat fleas are potential vectors for FeLV RNA in vitro and probably also in vivo.

To