Fleas and Flea Management - Urban Insect Pests: Sustainable Management Strategies - page 88

Fig. 6.1. Typical row of cat fl ea bites on human arm.

rattus , Rattus norvegicus and Mastomys
spp.) and a number of other species such as
gerbils ( Meriones spp.) and ground squirrels
( Spermophilus spp.). The main natural
reservoirs of the disease are in the steppes
and deserts of central Asia and Africa. Fleas
acquire the disease by feeding on the
infected rodents, and the bacteria then
develop within the fl ea's gut and eventually
cause a blockage. Subsequent feeding
attempts by the fl ea then result in
regurgitation of infective blood and infec-
tion of the new host. Infected fl eas therefore
pass the infection between rodents, and
from rodents to humans. In addition, fl eas
with blocked guts attempt to feed more
frequently, resulting in more contacts with
potential hosts.
The rat fl eas Xenopsylla cheopis and
Xenopsylla brasiliensis are the most
important vectors of Y. pestis worldwide
(Table 6.1) . In the laboratory, other fl ea
species, such as the northern rat fl ea
( Nosopsyllus fasciatus ), cat and dog fl eas
( C. felis and Ctenocephalides canis ) and the
human fl ea ( P. irritans ), have also been
shown to be capable of transmitting the
plague bacilli (Hinkle, 2008; Goddard,
2008) but are considered to be poor vectors.
Historically, plague transmission has been
characterized by a series of global pan-
demics: the fi rst in around AD 500, while the

second in mediaeval times was known as
the Black Death and resulted in the death of
around one third of the human population
of Europe. The third pandemic started in
the late 19th century and is continuing to
the present. Currently, the main centres of
plague transmission are in Central and East
Africa, East Asia, South America and the
western part of the USA. The number of
cases varies considerably but typically from
1000 to 2000 cases are reported annually to
the World Health Organization.
Cat Scratch Disease (CSD) of humans is
caused by the bacterium Bartonella henselae
and, although occurring worldwide, was
not fully described and understood until
the late 20th century. Cats are the major
reservoir of this disease and transmission of
B. henselae between cats is via bites of the
cat fl ea C. felis . Transmission from cats to
people occurs primarily through contamin-
ation of cat scratches with fl ea excrement
containing B. henselae , or possibly through
cat bites if blood or fl ea excrement
contaminates the bite wound. Cat fl eas can
support B. henselae and excrete viable
organisms in their faeces for up to 9 days
after taking an infective blood meal (Higgins
et al ., 1996). CSD is a self-limiting illness
characterized by development of papules,
vesicles and pustules at the primary
inoculation site, followed by fever and