Human infestation by pigeon fleas
28, 39], its relatives Argas polonicus [6, 35, 36] and Argas latus , and the red blood mite Dermanyssus gallinae [11, 16, 44, 47]. There are also reports on human invasions by the northern fowl mite Ornithonyssus sylviarum  and the bed bug Cimex lectularius .
Despite the pigeon flea (Ceratophyllus columbae) being a frequent ectoparasite of feral pigeons [18, 27, 37, 40, 48], we are aware of only 5 previous, partly anecdotal reports on human invasions. In 1961, pigeon fleas infested workers repairing the roof of a building populated by feral pigeons in Hamburg, Germany . Two further cases were observed in 1962 and 1964, in dwellings in Leipzig, Germany, with pigeon nests as putative sources of the infestations . In 1978, feral pigeons were repelled from the loft of the Natural History Museum of Basel, Switzerland. Some days after the closure of the loft, pigeon fleas attacked museum employees who worked in a neighbouring preparatory room . In a further, unpublished observation, a nest of feral pigeons was removed from the attic of a house. One year later, pigeon fleas invaded a woman living in the mansard apartment below (Marcus Schmidt, Zurich, personal communication). Unfortunately, all these reports lack information on the health effect of the invasions.
erythema starting 12-24 h after the bite). Appearance of both immediate and late skin reactions (overlap of both previous groups) was seen in 20% of the test persons . Repeated fleabites may lead to generalised allergic reactions. We have observed this in Mr X, who gradually developed generalised urticaria. Flea allergens may also cause respiratory allergy. Among persons with suspected cat allergy, 9% were in fact allergic to cat fleas, and a further 46% suffered from allergy both to cats and cat fleas .
Fleas are much feared as carriers of infectious diseases. In the past, rat and human fleas were vectors of bubonic plague and endemic typhus [4, 24]. Also nowadays, these insects may vector a wide range of infectious and parasitic diseases [1, 2, 4, 29, 46, 49]. Flea infestations remain a considerable health problem to both poor and rich alike, and may even occur in hospital . Summing up the unpleasant, itching skin reactions to fleabites with the well-deserved “bad name” of fleas, one should not be
surprised by severe psychological distress overwhelmed the couple described in this report.
Typically, animal fleas invade humans when devoid of their specific host . The couple described here, however, was attacked while the pigeons were still present on-site. It is possible that the favourable temperature provided by the heating tube had promoted propagation of the insects to such extent that the nesting pigeons became insufficient as the feed source, which had driven the fleas to seek a new host. In fact, the host specificity of fleas is not as strict as with many other arthropod ectoparasites . Cat flea (Ctenocephalides felis) is frequently found on dogs and other mammals [23, 30]. Dog fleas (C. canis) can, in turn, prey also on cats and foxes . Both cat and dog fleas frequently plague humans [5, 21, 31]. Other species that may also infest people include hen flea (Ceratophyllus gallinae), sparrow flea (Ceratophyllus fringillae), finch flea (Dasypsyllus gallinulae), hedgehog flea (Archaeopsylla erinacei), rabbit flea (Spilopsyllus cunniculi), and European rat flea (Nosopsyllus fasciatus) [5, 7, 21, 50]. On the other hand, human flea (Pulex irritans) frequently infests dogs, goats, and pigs, but also may be found on badgers, foxes and squirrels [9, 22, 25, 30]. Compared to the above species, pigeon flea seems restricted to birds. It is found almost exclusively in pigeons’ nests and henhouses . However, as this article demonstrates, the pigeon flea is also capable of attacking humans.
While feeding, fleas inject their saliva into the host’s body to prevent the blood from coagulating. The saliva has strong irritating and allergising properties [4, 13, 43]. In experimental conditions, controlled fleabites caused skin reaction in 62% of 269 test persons. An immediate reaction (itch, erythema, and eventually wheal within 20 min after the bite) was observed in 23%, whereas 59% had a late skin reaction (itching, indurated papulae with
We have documented a rare case of pigeon fleas (Ceratophyllus columbae) invading humans. This report demonstrates that even a single pigeon nest neighbouring human dwellings is sufficient to cause serious and long- lasting problems for the inhabitants.
The authors wish to thank Dr Peter Herger (Lucerne), Marcus Schmidt (Zurich), Gianni Morson (Basel), and Andreas Ochsenbein (Basel) for their kind assistance at various stages of preparing this paper.
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