Borrelia

The genus Borrelia comprises diverse species of spirochaetes that are associated with haematophagous arthropods (Paster et al., 1991 Paster & Dewhirst, 2000). Some Borrelia species are pathogenic for humans or for livestock. Other spirochaete groups with human pathogens are the treponemes, which include the human-restricted agent of syphilis, and the leptospires, which are mostly free-living spirochaetes that infect a wide variety of animals. The spirochaete phylum also contains a number of...

Perspective And Conclusions

Although more than 100 years have passed since the recognition of the importance of arthropod vectors in the transmission of many serious human pathogens, control of these diseases has not been achieved, and in recent years there has been a resurgence as a result of changes in public health policy, social factors, and the development of insecticide and drug resistance in the vectors and the pathogens they carry. In terms of public health policy, vector control programmes have frequently...

Gorelova N B Korenberg E I Kovaleskii Y V Shcherbakov S V 1995

Small mammals as reservoir hosts for Borrelia in Russia. Zentbl Bakteriol 282, 315-322. Gould, E. A., Zanotto, P. M. & Holmes, E. C. (1997). The genetic evolution of flaviviruses. In Factors in the Emergence of Arbovirus Diseases, pp. 51-63. Edited by B. Dodet. Paris Elsevier. Gould, E. A., de Lamballerie, X., Zanotto, P. M. & Holmes, E. C. (2001). Evolution, epidemiology, and dispersal of flaviviruses revealed by molecular phylogenies. Adv Virus Res 57, 71-103. Green, P. E. (1978)....

Introduction

Invertebrates, particularly insects, act as vectors of the most debilitating diseases in many already socially and economically compromised populations of the developing world. The diseases vectored include malaria, sleeping sickness, Chagas' disease, leishmaniasis, lymphatic filariases and river blindness, dengue and yellow fever, and schistosomiasis. Only the latter is transmitted by non-insectan invertebrates, i.e. snails of the genus Biomphalaria. Hurd (2003) recently pointed out that of...

Wildtype And Vaccine Strains Of Flaviviruses In Mosquitoes

It has long been known that whilst wild-type YFV can infect, disseminate and be transmitted by Ae. aegypti mosquitoes, the 17D strain, which is a live attenuated derivative used for human vaccination, can infect epithelial cells of the midgut but does not disseminate and is not transmitted (Roubaud et al., 1937 Whitman, 1937, 1939 Miller & Adkin, 1988 Jennings et al., 1994). Similarly, the YFV FNV vaccine strain is attenuated in mosquitoes (Davis et al., 1932 Roubaud & Stephanopoulo, 1933...

Infection of organs within the haemocoel

The haemocoel is the insect's body cavity and constitutes an open circulatory system containing the fluid haemolymph. In addition to the organs and muscles, the haemocoel contains cellular components of the insect immune system, for example haemocytes that are distributed in the haemo-lymph. Sriurairatna & Bhamarapravati (1977) reported replication of DEN-2V in haemocytes but this seems unusual. The biochemical and physiological make-up of the haemolymph can...

References

G. & Shope, R. E. (1977). Aedes aegypti strain fitness for yellow fever virus transmission. Am J Trop Med Hyg 26, 985-989. Allen, M. L., O'Brochta, D. A., Atkinson, P. W. & Levesque, C. S. (2001). Stable, germ-line transformation of Culex quinquefasciatus (Diptera Culicidae). J Med Entomol 38, 701-710. Armstrong, P. M. & Rico-Hesse, R. (2001). Differential susceptibility of Aedes aegypti to infection by the American and Southeast Asian genotypes of dengue type...

Models of vector competence

Tree Eukaryote Cavalier Smith

Mathematical modelling of vector-borne diseases began with Hamer (1906) and Ross (1911) modelling malaria transmission, followed by Reed and Frost (cited in Abbey, 1952), who developed a stochastic model of epidemics assuming a binomial distribution. The geographical extent, population at risk for infection and the levels of mortality of malaria make it a prime candidate for mathematical modelling and a vast literature exists on this topic (Bailey, 1982 Bruce-Chwatt, 1976 Dietz et al., 1974...

Tick Vectors And Reservoirs

With the exception of Borrelia recurrentis, which is transmitted from person-to-person by the human louse, Pediculus humanus, the vectors of Borrelia spp. are ticks. Ticks (Ixodidae) are a subgroup of the order of mites (Acari), which are, in turn, members of the larger group Arachnida. Ticks are a form of parasitic mite (Parasitiformes) that is entirely dependent on a periodic blood meal for all its biosynthetic activities and for reproduction. The two major monophyletic clades of ticks are...