mechanical transmission of the spirochaetes by eye flies

From: JWissmille (jwissmille_at_aol.com)
Date: 09/02/04 

Date: 02 Sep 2004 01:29:48 GMT

Yaws(frambesia) is a spirochetal disease indistinguishable from syphilis with
blood tests. It is caused by Treponema pertenue.
Treponemataceae is the name of the family of spiral organisms belonging to the
order Spirochaetales; includes the genera Borrelia, Leptospira, and
Treponema.(Taber's)

".... In the case of Yaws, mechanical transmission of the spirochaetes by eye
flies (Hippelates pallipes) in the West Indies is thought to be most likely.
..."

TITLE: Pathogen transmission in relation to feeding and digestion by
haematophagous Arthropods.
AUTHORS: Langley PA
SOURCE: Acta Trop 1975;32(2):116-24
CITATION IDS: PMID: 240257 UI: 76016115

ABSTRACT: The blood feeding habit, especially among opportunist feeders such as
tabanids and Stomoxys is known to result in transmission of diseases for which
the vectors are not the obligate or alternate hosts. Thus, mechanical
transmission of trypanosomes such as T. vivax can occur in cattle herds outside
tsetse fly areas where tabanids are actively feeding. In the case of Yaws,
mechanical transmission of the spirochaetes by eye flies (Hippelates pallipes)
in the West Indies is thought to be most likely. The spirochaetes remain motile
in the pharynx and oesophageal diverticula for several hours but are apparently
immobilised in the midgut (Kumm & Turner, 1936). There is apparently no
development ofspirochaetes in the fly. They have been shown to pass through
houseflies, but in mechanical transmission, biochemical transformation or
adaptation of the pathogen is not implied. Virus transmission is common among
arthropods and transovarial transmission to succeeding generations is frequent
in mites and ticks. Although Yellow Fever virus is not transovarially
transmitted by its vector Aedes aegypti, the mosquito only becomes infective
some time after ingesting an infected blood meal (Chandler, 1955). Thus,
metabolic or biochemical changes or adaptations in the virus or in the vector
are in some way implicated, as they must also be in transovarially transmitted
viruses. However, the causal relationships between virus infectivity and vector
physiology are poorly understood. As with virus infections, those disease
organisms possessing a cyclical host/vector relationship will possess a
variable infectivity potential which is not necessarily related to the
abundance of any of the organisms in the cycle. Clearly, feeding behavior and
host preferences of the vector are important in determining the rate and extent
of disease transmission, and such parameters can be quantified in
epidemiological studies. However, a complete understanding of the factors
concerned in cyclical disease transmission also depends on a knowledge of the
physiology of the organisms involved, and particularly of the interdependence
of their physiologies. The subject is vast, and it is proposed to illustrate
the problems involved and the progress made, by reference largely to
trypanosome transmission by tsetse flies (Glossina spp.).MAIN MESH HEADINGS:
*Arthropod Vectors
Arthropods/*physiology
*Digestion
*Feeding Behavior
Trypanosoma/*physiology ADDITIONAL MESH HEADINGS: Adaptation, Physiological
Animal
Arthropods/metabolism
Arthropods/parasitology
Blood
Cattle
Comparative Study
Female
Human
Male
Species Specificity
Support, U.S. Gov't, Non-P.H.S.
Trypanosoma/isolation & purification
Trypanosoma/pathogenicity PUBLICATION TYPES: JOURNAL ARTICLE LANGUAGES: Eng

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