Human flea

Abstract: We detected Rickettsia felis DNA in Ctenocephalides felis and Bartonella quintana DNA in 3 Pulex irritans fleas taken from a pet Cercopithecus cephus monkey in Gabon, sub-Saharan Africa. This is the first report of B. quintana in the human flea.

Abstract: The human flea, Pulex irritans L., has been recovered from archaeological sediments in Viking York (England), Dublin (Ireland) and abandoned farm sites in Norse Greenland. In contrast with the other human ectoparasites, however, the origins of the flea appear to be Central to South American, where several congeners are known. The probable routes by which the species reached Western Europe are discussed and resolved in favour of a Beringian and Asiatic one, at any time during the Postglacial. Although this flea is presently relatively promiscuous,

Abstract: To the Editor: Yersinia pestis (family Enterobacteriaceae) is a bacterium that can cause high rates of death in susceptible mammals and can provoke septicemic, pneumonic, and bubonic plague in humans (1). This zoonotic pathogen can be transmitted directly by infectious droplets or by contact with contaminated fluid or tissue or indirectly through flea bites (1). Plague was introduced into Madagascar in 1898 from rat-infested steamships that had sailed from affected areas (2). Now, Madagascar is 1 of 2 countries in Africa that have reported cases of human plague every year since 1991 (3). During January 2008–January 2013, the number of human plague cases reported in Madagascar ranged from 312 to 648 per year. Of these, 61.8%–75.5% were laboratory confirmed (National Plague Laboratory of the Ministry of Health, pers. comm.). Most (>83%) confirmed cases were bubonic plague, which most commonly results from flea bites, suggesting that these bites were the most common mode of Y. pestis transmission. In Madagascar, Xenopsylla cheopis fleas have been known as the primary plague vector in urban areas, whereas Synopsyllus fonquerniei fleas have been usually involved in plague transmission in rural areas (2). In January 2013, a total of 9 suspected bubonic plague cases, 3 confirmed, were reported in Soavina, a rural area in the district of Ambatofinandrana, Madagascar. Domestic fleas were collected with candle traps inside 5 houses during 3 nights (Table). Fleas were also caught on small mammals trapped inside houses and outside in the sisal fences and rice fields (Table). A total of 319 fleas belonging to 5 species in 5 genera were collected inside and outside the houses, an average of 44 per house (maximum 71): Pulex irritans, Echidnophaga gallinacea, and Ctenocephalides canis fleas were collected inside the houses (244, 76.5%), and S. fonquerniei and X. cheopis fleas were collected outside (75, 23.5%). The human flea, P. irritans, was the most collected flea species (233, 73.3%), followed by S. fonquerniei (62, 19.4%), X. cheopis (13, 4.1%), E. gallinacea (10, 3.1%), and C. canis (1, 0.3%). Table Fleas collected inside and outside houses in Soavina, Madagascar, January 2013 Bacterial DNA was extracted from 277 fleas of 5 species: 233 P. irritans, 24 S. fonquerniei, 9 X. cheopis, 10 E. gallinacea, and 1 C. canis. PCR to detect Y. pestis was performed by using primers YP1 (5′-ATC TTA CTT TCC GTG AGA AG-3′) and YP2 (5′-CTT GGA TGT TGA GCT TCC TA-3′) to amplify a 478-bp fragment (4). Y. pestis DNA was then amplified and genotyped by Beckman Coulter Genomics Inc. (Takeley, United Kingdom). The positive control was Y. pestis reference strain (strain 6/69, 3 × 108 bacteria/mL; Institut Pasteur de Madagascar). Detection of Y. pestis was carried out on 274 fleas belonging to 5 flea species: 230 P. irritans (181 unfed and 49 engorged), 24 S. fonquerniei (15 unfed and 9 engorged), 9 X. cheopis (8 unfed and 1 engorged), 10 E. gallinacea (blood-feeding status not identified), and 1 unfed C. canis. Y. pestis was detected in 9 P. irritans fleas (7 male [6 unfed and 1 engorged] and 2 [engorged] female) from 3 houses, including the house where a confirmed human case of plague had occurred (Technical Appendix). Eight sequences (GenBank accession nos. {"type":"entrez-nucleotide-range","attrs":{"text":"KJ361938-KJ361945","start_term":"KJ361938","end_term":"KJ361945","start_term_id":"608789158","end_term_id":"608789172"}}KJ361938-KJ361945) were obtained and share 99% nucleotide homology with plasminogen activator genes of Y. pestis published in GenBank (accession nos. {"type":"entrez-nucleotide","attrs":{"text":"AF528537","term_id":"22212811","term_text":"AF528537"}}AF528537, {"type":"entrez-nucleotide","attrs":{"text":"AY305870","term_id":"32250732","term_text":"AY305870"}}AY305870). No Y. pestis was detected in the 24 S. fonquerniei, 9 X. cheopis, 10 E. gallinacea, or 1 C. canis fleas collected. Although only X. cheopis and S. fonqueniei fleas had previously been described as plague vectors in Madagascar, P. irritans fleas were most commonly collected during this field study; engorged and unfed male and female P. irritans fleas carried Y. pestis. Other studies have found P. irritans fleas in the plague risk area in other countries in Africa (5,6); one study found that P. irritans fleas may play a role in plague epidemiology in Tanzania (5). Data on P. irritans fleas in rats make it unlikely that these fleas are involved in rat-to-human transmission of Y. pestis in Madagascar. During 1922–1995, a total of 118,608 rats were caught and examined in Madagascar, but only 148 P. irritans fleas were identified, and none have been found on rats since 1996 (http://www.pasteur.mg/spip.php?rubrique124). The high density of P. irritans fleas we observed in villages where plague outbreaks occurred in late 2012 and early 2013 (http://www.pasteur.mg/spip.php?rubrique124) supports the possibility that P. irritans fleas played a role in domestic human-to-human transmission of Y. pestis during these outbreaks. Technical Appendix: Agarose gel electrophoresis showing positive PCR results for Yersinia pestis in DNA of 9 Pulex irritans fleas collected from 3 houses in an area of Madagascar where plague outbreaks occurred in late 2012 and early 2013. Click here to view.(47K, pdf)

Abstract: Adult fleas are haematophagous ectoparasites of warm-blooded vertebrates, particularly mammals. Among them, the cat flea (Ctenocephalides felis) and the human flea (Pulex irritans) have high veterinary-medical significance, owing to their cosmopolitan distribution and role in the transmission of important vector-borne pathogens. While the taxonomy of Ct. felis has been investigated on a morphological basis during the past decades, its molecular-phylogenetic analyses have been only recently conducted. This study expands the knowledge on Ct. felis from hitherto less studied geographical regions, and includes representatives from additional flea families, less investigated with molecular approaches. Fleas were collected in four countries of the Mediterranean Basin (Croatia, Italy, Malta and Israel), as well as in Hungary, from domestic and wild carnivores, rodents and humans. The DNA extracts of representative fleas (n = 148), belonging to ten species of eight genera, were used for PCR amplification of part of their cytochrome c oxidase subunits 1, 2 (cox1, cox2) and 18S rRNA genes, followed by sequencing and phylogenetic analyses. The majority (65.6%) of Ct. felis felis cox2 sequences showed 99.4–100% similarity to each other (haplogroup A), whereas those from Malta and Israel had 98.1–98.7% sequence similarity (haplogroup B), and a third sequence from Israel (haplotype C) had as low as 96.3% sequence similarity in comparison with a reference sequence from group “A”. Except for the shape of the head, no consistent morphological differences (e.g. in chaetotaxy) were found between haplogroups “A” and “C”. Haplotypes of Ct. canis were genetically more homogenous, with 99.6–100% sequence similarity to each other. However, when P. irritans collected from humans was compared to those from three species of wild carnivores, these only had 96.6% cox2 similarity. The mouse flea, Leptopsylla segnis and the northern rat flea, Nosopsyllus fasciatus were both shown to have haplotypes with low intraspecific cox2 similarities (96.2 and 94.4%, respectively). Taken together, differences between mitochondrial lineages within four flea species exceeded that observed between two Chaetopsylla spp. (which had 97.3% cox2 similarity). The topologies of cox1 and cox2 phylogenetic trees were in line with relevant sequence comparisons. Conversely, 18S rRNA gene analyses only resolved differences above the species level. Ctenocephalides felis felis, P. irritans, L. segnis and N. fasciatus were shown to have such a high level of mitochondrial gene heterogeneity, that the uniformity of these flea taxa should be reconsidered. Although the present results are limited (especially in the case of L. segnis and N. fasciatus), there appears to be no geographical or host restriction, which could explain the divergence of these genetic lineages.