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| Journal of the New Zealand Medical Association,
25-November-2005, Vol 118 No 1226
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Prevalence of human pathogens in cat and dog fleas in
New Zealand
Patrick Kelly, Jean-Marc Rolain, Didier Raoult
To date, murine typhus is the only rickettsial disease known
to occur in New Zealand.1 The disease is caused by
Rickettsia typhi which is transmitted
by the oriental rat flea, Xenopsylla
cheopis. Recently, the cat flea,
Ctenocephalides felis, has been
recognised as a vector of emerging human pathogens including
R. felis,
Bartonella henselae and
B. clarridgeiae.1 In a preliminary
study, DNA of R.
felis, B. henselae and
B. clarridgeiae were detected in cat
fleas from the town of Palmerston North in New Zealand.2 To provide further
information on the prevalence of these pathogens in New Zealand, we studied
fleas from a further three sites in the North Island.
Materials and MethodsFleas—Fleas
were collected from cats and dogs presenting to private veterinary practices in
Matamata, Lower Hutt, and New Plymouth townships. The fleas were preserved in
95% ethanol and identified using morphological criteria.3
Polymerase chain
reaction (PCR)—Fleas were placed individually in sterile Eppendorf
tubes and washed in sterile distilled water for 5 minutes before being macerated
with a sterile pipette. DNA was extracted with the QIAamp Tissue Kit (QIAGEN,
Hilden, Germany) according to the manufacturer’s instructions. This kit
was also used to extract DNA from a human body louse reared in our laboratory
(Unité des Rickettsies, France) under standard conditions and used as a
negative control.
The flea DNA extracts were assayed as described
previously4 with genus-specific primers for
Bartonella derived from the
its (intergenic spacer region) and the
pap 31 (31-kDa major protein) gene, and
for Rickettsia spp. with primers
derived from the gltA (citrate
synthase) and rOmpB (rickettsial outer
membrane protein B) genes. Positive controls consisted of DNA extracted from
laboratory cultures of B. elizabethae
(for Bartonella) and
R. montanensis (for
Rickettsia).
Positive PCR products were sequenced using the
dRhodamine Terminator cycle-sequencing ready reaction kit (PE Applied
Biosystems, Les Ulis, France) according to the manufacturer’s
instructions. Sequences obtained were compared with those in the GenBank DNA
database using the BLAST program (version 2.0, National Center for Biotechnology
Information, http://www.ncbi.nlm.nih.gov).
ResultsBetween 1 and 13 fleas were collected from individual cats
and dogs presenting to the veterinary practices in the study. DNA of
R. felis,
B. henselae and
B. clarridgeiae was detected in 19%,
11%, and 7% of the 114 C. felis
collected, respectively. No products were obtained from the negative
control DNA from a human body louse and positive controls revealed appropriate
amplicons.
Rickettsia felis
was identified in fleas from all practices, while
B. henselae was found in fleas from two
practices (Lower Hutt and Matamata) and B.
clarridgeiae in fleas from one practice (Matamata). The DNA of both
B. henselae
and B. clarridgeiae was found in
three fleas (from two animals); B.
clarridgeiae and R. felis in one
flea; B. henselae and
R. felis in five fleas (from three
animals); and R. felis,
B. henselae and
B. clarridgeiae in two fleas (from one
animal). No PCR products were obtained from the three
C. canis.
DiscussionFlea-borne spotted fever caused by
R. felis is an emerging infectious
disease that has been reviewed recently in this journal.1 Infections are
transmitted by the cat flea, which is also the reservoir host of
R. felis. In a preliminary study in
2004, 10% of C. felis collected from
dogs and cats in Palmerston North contained DNA of
R. felis.2 We have now found DNA of
R. felis in cat fleas from each of
three other sites sampled, and the overall prevalence is 15% (32/213). While
flea-borne spotted fever has yet to be reported in New Zealand, our study shows
the aetiological agent is widely
distributed and common in cat fleas in the country.
Bartonella henselae
and B. clarridgeiae are also
emerging human pathogens transmitted by C.
felis.4,5 Infections can result in a wide variety of clinical syndromes
which have been reviewed recently.1 In New Zealand, cat scratch disease,1
neuroretinitis and encephalopathy6,7 occur; and a preliminary study in
Palmerston North revealed DNA of B. henselae
and B. clarridgeiae in 3% and 1%
of the C. felis studied, respectively.2
We have now found DNA of
B. henselae in 11% of the fleas from
two of the three additional sites we surveyed. Similarly, we found
B. clarridgeiae in cat fleas (7%) from
one of the three new sites we sampled, thus indicating both organisms probably
occur widely in New Zealand.
Most New Zealand households have cats and dogs as companion
animals, and fleas are very common ectoparasites on these animals. Although cat
fleas prefer to feed on pets, they have a wide host range and will readily feed
on people.8 With the high prevalences of R.
felis, B. henselae and
B. clarridgeiae in cat fleas and their
wide distribution in New Zealand, it would seem likely that people are not
uncommonly infected.
Of note is our finding that DNA of more than one organism
occurred in 10 out of 22 PCR-positive fleas, thus indicating that multiple
infections may be acquired from a single flea. Diagnosing single and multiple
infections is often not easy as symptoms are generally non-specific. Our study
also shows that health workers should have a high index of suspicion of
infections in patients with a history of ‘flea-bites.’
Author information:
Patrick Kelly, Professor, Ross University School of Veterinary Medicine,
Basseterre, St Kitts, West Indies; Jean-Marc Rolain, Professor, Unité des
Rickettsies, CNRS UMR 6020, Faculté de Médecine, Marseille,
France; Didier Raoult, Professor, Unité des Rickettsies, CNRS UMR 6020,
Faculté de Médecine, Marseille, France
Correspondence:
Patrick Kelly, Ross University School of Veterinary Medicine, PO Box
334, Basseterre, St Kitts, West Indies. Fax: (869) 465 1203; email: pkelly@rossvet.edu.kn
Acknowledgements: We
thank Steve De Grey, Christine Mander, and Julian Shorten for providing flea
specimens for our study.
References:
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