Differential diagnosis between Tunga penetrans (L., 1758) and T. trimamillata Pampiglione et al., 2002 (Insecta, Siphonaptera), the two species of the genus Tunga parasitic in man

Of the ten currently known species of sand fleas, only two, Tunga penetrans and Tunga trimamillata, are known to be parasites of man, besides other warm blooded animals, most of which are peridomestic. The hosts of the other eight are limited to a few genera of wild mammals. T. trimamillata was only recently identified and differentiated from T. penetrans by features of the gravid female phase. In the present paper the different morphological characters of both for non-gravid females and males of the two species are described. In the non-gravid-females the distinguishing characters are: a) differences in the length of the first two segments of the maxillary palps (the first is the longest in T. trimamillata, whereas the second is the longest in T. penetrans), this feature is associated with another character i.e. the presence of short, thick spines in addition to the bristles on the surface of the segments only in T. trimamillata; b) the presence, only in T. trimamillata, of a row of spines on the antero-medial surface of the libia of the 3rd pair of legs; c) the last abdominal spiracle protrudes in T. trimamillata but not in T. penetrans; d) the hood of the hilla in spermatheca is surrounded by a papilla only in T. penetrans. The following morphological characters differentiate males of T. trimamillata and T. penetrans: a) T. trimamillata has a row of spines on the antero-medial surface of the tibia of the 3rd pair of legs; b) the diameter of the abdominal spiracles of T. trimamillata is smaller than that of T. penetrans and the edges of the spiracles are more regular; c) the claspers and aedeagus of T. trimamillata are shorter than those of T. penetrans; d) the profile of the oedeagal apodeme differs between the two species.     

Blood-feeding of Tunga penetrans males

The jigger Tunga penetrans (Linnaeus, 1758: type-species of the family Tungidae) is the smallest known species of flea (Siphonaptera), causing serious ectoparasitosis of humans and domestic animals. The adult female Tunga lodges in the epidermis of the mammalian host, grows by neosomy, becomes gravid and expels eggs. Relatively little is known about the free-living male Tunga adults. Among impoverished communities of Fortaleza in north-east Brazil, we observed T. penetrans males as well as females penetrating the skin of human hosts. After penetrating the epidermis for a few hours, evidently for capillary feeding from the dermis, males withdrew their mouthparts and crawled away, whereas the females remained completely embedded, hypertrophying to become gravid, eventually dying in situ after oviposition. Caged rats were placed on the sandy soil and examined periodically for Tunga infestation. On five rats we obtained 140 females embedded and we detected 75 males biting, with rat erythrocytes observed in the proventriculus and midgut of all five males dissected and examined microscopically. This confirms that T. penetrans males are hamatophagous ectoparasites of mammals.     

The animal reservoir of Tunga penetrans in severely affected communities of north-east Brazil

Tungiasis is a zoonotic ectoparasitosis caused by the sand flea Tunga penetrans L. (Siphonaptera: Tungidae). This disease is hyperendemic in poor communities of north-east Brazil, causing considerable morbidity in affected human populations, but the animal reservoirs have not been investigated previously in Brazil. To assess the prevalence and intensity of T. penetrans infection in domestic and peri-domestic animals, as well as in the human population, we surveyed two typical communities of north-east Brazil: an urban slum and a traditional fishing village. In the slum we examined 849 humans, 121 cats, 82 dogs, 2 pigs, 2 rabbits, 1 monkey and 56 rodents, comprising 34 rats (Rattus rattus L.) and 22 mice (Mus domesticus L). In the fishing village we examined 505 humans, 68 dogs, 37 cats, 7 donkeys, 4 cattle, 3 pigs and 1 monkey. Tungiasis was common among dogs and cats of both communities, with respective prevalence rates of 67.1% (95% CI: 55.8-77.1) and 30.9% (95% CI: 20.2-43.3) in dogs, 49.6% (95% CI: 40.4-58.8) and 32.4% (95% CI: 18.0-49.8) in cats. Slum rats were 41.2% (95% CI: 24.6-59.3) infested, but the other animals were not. Human prevalence rates were 54.4% (95% CI: 51.0-57.8) in the slum and 52.1% (95% CI: 47.6-56.5) in the fishing village. High prevalence rates (range 31-67%) of tungiasis in humans, pets and rats (but apparently not other animals) indicate the need for an eco-epidemiological approach to control of this anthropo-zoonotic problem.     

Wolbachia infection in the newly described Ecuadorian sand flea, Tunga trimamillata

Wolbachia pipientis is an intracellular endosymbiont producing reproductive alterations in its hosts. This bacterium have been reported in many arthropods and nematodes. By PCR amplification and sequencing of the 16S rDNA and ftsZ genes we have identified a Wolbachia strain in the newly described sand-flea, Tunga trimamillata. Prevalence of this endosymbiont in the 26 individuals screened is equal to 35%. Sympatric and allopatric specimens of the related species Tunga penetrans were also analysed, but in contrast to literature data, Wolbachia appears absent in the presently analysed 24 specimens. Field studies evidence a female-biased sex-ratio in T. trimamillata, suggesting that Wolbachia may cause sex-ratio distortion in this species. By means of BLAST search and phylogenetic analysis we found that the Wolbachia strain from T. trimamillata pertains to the arthropod-infecting Wolbachia; this strain is highly differentiated from the Wolbachia strain of T. penetrans described in literature.     

Molecular characterization of Tunga trimamillata and T. penetrans (Insecta, Siphonaptera, Tungidae): taxonomy and genetic variability

A new species of the genus Tungo, T. trimamillata has recently been described on the basis of several morphological traits. To explore the taxonomic status of this flea with respect to T. penetrans, we undertook a molecular analysis of cytochrome oxydase II and 16S rDNA mitochondrial genes and of the internal transcribed spacer 2 nuclear marker on samples of both species. Maximum Parsimony evaluations of the three data set indicate a differentiation compatible with a specific rank between the two fleas with very high levels of divergence. Both mitochondrial and nuclear data are in line with a recent bottleneck in the Malagasy population of T. penetrans, possibly due to the recent colonisation of Africa via human transportation. Further, significantly lower mitochondrial variability in the Ecuadorian populations of T. penetrans with respect to the T. trimamillata ones is also evidenced.     

Description of Tunga bonneti n. sp. from Chile (Siphonaptera: Tungidae) with notes on specificity, chorology, dermecos and phenology

Smit (1968) misreported Tunga libis from Chile. Here we describe this flea as a new species. We analyzed free life females, male and embedded females. Moreover, we include data about its natural history and biology. These data will allow a better understanding about other Tunga fleas, and particularly for collecting males, which remain unknown to date.     

Tunga penetrans: molecular identification of Wolbachia endobacteria and their recognition by antibodies against proteins of endobacteria from filarial parasites

In search of Wolbachia in human parasites, Wolbachia were identified in the sand flea Tunga penetrans. PCR and DNA sequencing of the bacterial 16S rDNA, the ftsZ cell division protein, the Wolbachia surface protein (wsp) and the Wolbachia aspartate aminotransferase genes revealed a high similarity to the respective sequences of endosymbionts of filarial nematodes. Using these sequences a phylogenetic tree was generated, that indicates a close relationship between Wolbachia from T. penetrans and from filarial parasites, but possibly as a member of a new supergroup. Ultrastructural studies showed that Wolbachia are abundant in the ovaries of neosomic fleas, whereas other, smaller and morphologically distinct, bacteria were observed in the lumen of the intestine. Wolbachia were labeled by immunohistology and immunogold electron microscopy using polyclonal antibodies against wsp of Drosophila, of the filarial parasite Dirofilaria immitis, or against hsp 60 from Yersinia enterocolitica. These results show that as in filariasis, humans with tungiasis are exposed to Wolbachia. Furthermore, antisera raised against proteins of Wolbachia from arthropods or from filarial parasites can be immunologically cross-reactive.     

Bartonella and Rickettsia in fleas and lice from mammals in South Carolina, U.S.A.

Species in the genera Bartonella and Rickettsia are vector-borne pathogens of humans and domestic animals. The natural reservoirs and enzootic transmission cycles of these bacteria are poorly known in South Carolina. Thirteen species of lice and fleas were collected from urban animals and screened for the presence of Bartonella and Rickettsia by PCR amplification using genus-specific primers. Bartonella henselae was present in cat fleas (Ctenocephalides felis) from Virginia opossums (Didelphis virginiana) and a novel genotype of Bartonella was detected in Orchopeas howardi from an eastern gray squirrel (Sciurus carolinensis). We detected R. typhi and three novel genotypes Rickettsia in other species of fleas and lice. Rickettsia typhi, the causative agent of murine typhus, was detected in two pools of lice (Enderleinellus marmotae) from the woodchuck (Marmota monax). Cat fleas harbored one of two novel genotypes of Rickettsia. A third novel Rickettsia was detected in Orchopeas howardi from an eastern gray squirrel.     

A mixed-methods approach to understanding domestic dog health and disease transmission risk in an indigenous reserve in Guyana,South America

Domestic dogs (Canis lupus familiaris) can transmit a variety of pathogens due to their ubiquitousness in urban, rural and natural environments, and their close interactions with wildlife and humans. In this study, we used a mixed-methods approach to assess the role of domestic dogs as potential intermediaries of disease transmission from wildlife to humans among indigenous Waiwai in the Konashen Community Owned Conservation Area, Guyana. To address these objectives we 1) performed physical examinations and collected biological samples to assess Waiwai domestic dog health, and 2) administered questionnaires to characterize the role of dogs in the community and identify potential transmission pathways between wildlife, dogs, and humans. We observed ectoparasites on all dogs (n = 20), including: fleas (100%), ticks (15%), botflies (30%), and jigger flea lesions (Tunga penetrans) (80%). Ten percent of dogs were seropositive for Ehrlichia canis/ewingii, 10% were positive for Dirofilaria immitis, and one dog was seropositive for Leishmania infantum. All dogs (n = 20) were seronegative for: canine distemper virus, Brucella canis, Leptospira serovars, Trypanosoma cruzi, Anaplasma phagocytophilum/platys and Borrelia burgdorferi. Our questionnaire data revealed that the Waiwai remove ectoparasites from their dogs, clean up dog feces, and administer traditional and/or Western medicine to their dogs. White blood cell, strongyle-type ova, and eosinophil counts were lower in dogs that were not frequently used for hunting, dogs that did receive traditional and/or western medicine, and dogs that were frequently kept in elevated dog houses, although differences were not statistically significant. While our results suggest that the Waiwai have developed cultural practices that may promote dog health and/or prevent zoonotic disease transmission, more research is necessary to determine the efficacy of these practices. Our study provides important data on the health of dogs and the potential for disease transmission to humans in a zoonotic hotspot.     

Anatomy of Tunga trimamillata Pampiglione et al., 2002 (Insecta, Siphonaptera, Tungidae) and developmental phases of the gravid female

This paper deals with some internal anatomical features observed in histological sections and freshly dissected mounts of Tunga trimamillata, a Siphonaptera recently discovered in Andean regions of Ecuador from several mammals, including man. It was possible to study in males and also non-gravid and gravid females, the location and anatomy of several organs not previously described for this species: the testes, epididymis, ganglia, Malpighian tubules, eyes, rectal ampulla with one of its pads and structures which could be interpreted as midgut diverticula, whose presence has not been recorded in the Siphonaptera. The process of neosomy in the female during pregnancy is illustrated by photographs of the consecutive developmental phases, taken at the stereomicroscope. Furthermore, some details of the exoskeleton, spermatheca during different phases of pregnancy of the gravid female and the presence of a foreign body (parasite?) within the haemocoel have been displayed in specimens cleared with Hoyer's medium.     

Emergence/re-emergence of Echinococcus spp.--a global update

This review provides an update of the biological aspects of the genus Echinococcus and focuses on newly recognized endemic areas. Infection with the intermediate cystic stage of all species of Echinococcus causes disease and incapacity in animals and humans, and in the most serious cases, death of the host. Transmission of Echinococcus to new continents has occurred during European colonisation and the parasite has often taken advantage of Echinococcus-naive wildlife populations in these new environments, incorporating them into its transmission pattern. Echinococcus granulosus consists of a complex of 10 strains. Host specificities of these strains have important implications for transmission and control. As a result of human behaviour and/or political instability in a number of countries Echinococcus is re-emerging as an important public health issue. The importance of wildlife reservoirs in perpetuating transmission and as a source of infection for domestic animals and humans is addressed. The review also refers to the transmission pattern of a recently described new species, Echinococcus shiquicus, from China.     

Survey of Flea Infestation in Dogs in Different Geographical Regions of Iran

Medically important arthropods, including fleas, play an important role in causing clinical disorders and disease in man and domestic animals. This study was conducted to determine the seasonal flea infestations for domestic dogs from different geographic regions of Iran. A total of 407 fleas, belonging to 5 different species, were recovered from 83 domestic dogs from 3 regions. There was a distinctive pattern of species distribution and infestations with the highest infestation rates observed in a temperate climate and higher rainfall. Additionally, fleas were observed over all seasons, except February and March, with the highest infestation rate observed in August (24.7%) and the lowest rate in January (1.7%). They also parasitize dogs with a different spectrum of species. The cat flea, Ctenocephalides felis (67.5%), exhibited the highest prevalence among all flea species found on dogs. Thus, climatic conditions and seasonal patterns impact on flea infestation and must be considered in developing control programs.     

The patterns of tungiasis in Araruama township, state of Rio de Janeiro, Brazil

This paper describes patterns of infestation with Tunga penetrans (L., 1758) within the poor community of Araruama municipality, State of Rio de Janeiro, Brazil, assessed by the number of persons and domestic animals parasitized. The overall prevalence of infestation was 49.2% (211 parasitized hosts) of the 429 examined. Humans (p < 0.01) and dogs (p < 0.01) were the most important hosts with 62.6% and 35.6% respectively. Dogs were considered as the potential infestation source to humans. Considering sex and age groups, both measures showed a significant difference (p < 0.01): female (62.2% infested of 143 examined) and male (43.9% infested of 98 examined). All age classes were found infested with significant difference (G = 42.5; p < 0.01) and most of the infestation occurred in children in the 0-9-year old category (27.3%). In contrast and based on mean of chigoe burden per person, the parasitic intensity was significantly higher on male than on female in all age categories, except for the 50+ (H = 27.1; p < 0.01) and decreasing with the increase of age (chi2 = 69.7, A = -124.6, p < 0.01). Growing urbanization, improved housing and sewage systems, use of appropriate footwear, examination of the feet principally in young children, antitetanus prophylaxis and reduction of stray dogs population are the major prophylactic methods recommended.     

青海省寄生于有蹄类的蠕形蚤

目前,在青海省已发现寄生于有蹄类的蠕形蚤3属8种和亚种,其中有4新种和亚种,是我国蠕形蚤最多的省份。蠕形蚤是危害家畜和其它有蹄类动物的主要害虫之一,应采取有效措施予以预防。     

Animal Reservoirs of Zoonotic Tungiasis in Endemic Rural Villages of Uganda

Background

Animal tungiasis is believed to increase the prevalence and parasite burden in humans. Animal reservoirs of Tunga penetrans differ among endemic areas and their role in the epidemiology of tungiasis had never been investigated in Uganda.

Methods and Findings

To identify the major animal reservoirs of Tunga penetrans and their relative importance in the transmission of tungiasis in Uganda, a cross sectional study was conducted in animal rearing households in 10 endemic villages in Bugiri District. T. penetrans infections were detected in pigs, dogs, goats and a cat. The prevalences of households with tungiasis ranged from 0% to 71.4% (median 22.2) for animals and from 5 to 71.4% (median 27.8%) for humans. The prevalence of human tungiasis also varied among the population of the villages (median 7%, range 1.3–37.3%). Pig infections had the widest distribution (nine out of 10 villages) and highest prevalence (median 16.2%, range 0–64.1%). Pigs also had a higher number of embedded sand fleas than all other species combined (p<0.0001). Dog tungiasis occurred in five out of 10 villages with low prevalences (median of 2%, range 0–26.9%). Only two goats and a single cat had tungiasis. Prevalences of animal and human tungiasis correlated at both village (rho = 0.89, p = 0.0005) and household (rho = 0.4, p<0.0001) levels. The median number of lesions in household animals correlated with the median intensity of infection in children three to eight years of age (rho = 0.47, p<0.0001). Animal tungiasis increased the odds of occurrence of human cases in households six fold (OR = 6.1, 95% CI 3.3–11.4, p<0.0001).

Conclusion

Animal and human tungiasis were closely associated and pigs were identified as the most important animal hosts of T. penetrans. Effective tungiasis control should follow One Health principles and integrate ectoparasites control in animals.     

Pestiferous nature, resting sites, aggregation, and host-seeking behavior of the eye fly Siphunculina funicola (Diptera: Chloropidae) in Thailand.

Species of eye flies and eye gnats (Diptera: Chloropidae) are severe and persistent pests of man, domestic and wild animals, and potential vectors of pathogens. The species prevailing in the Oriental region belong to the genus Siphunculina, while those in the Neotropic and Nearctic regions belong to Liohippelates and Hippelates. These are small insects of 1-2 mm that feed on wounds, lacerations, scratches, and mucous membranes of man and higher animals. One species, Siphunculina funicola, commonly known as the Oriental eye fly, is considered the most anthropophilic in the genus, with potential involvement in the spread and mechanical transmission of infectious agents to humans and animals. Very little is known about the biology, prevalence, host-seeking, and aggregation behavior of this species in South and Southeast Asia. We initiated studies on biological aspects of this potential vector and human pest in central Thailand. The most significant findings of our study were the aggregation behaviors of S. funicola, that both sexes attack hosts, and that males outnumbered females attacking humans, dogs, and other domestic animals. They feed on wounds, scabs, lacerations, eyes, and mucous membranes. They hover around and feed on hosts during the daylight hours when host-seeking activities are more pronounced at temperatures above 25-27 degrees C under calm conditions. We noted that large masses of males and females aggregated on a variety of hanging objects such as strings, trailings, electrical lines, decorations, ropes, twines, abandoned cob webs, clothes hangers, and other hanging substrates in open shade of structures and dwellings. This behavior of eye flies brings them closer to human and animal hosts. In these aggregations, both males and females were present, with mating pairs frequently noted. In the aggregations, about 37% of the females had fully developed eggs in the rainy season, but only <1-3.6% were gravid in the hot and dry season. The average number of eggs per female was generally 42 to 44.     

Treatment of Tungiasis with Dimeticone: A Proof-of-Principle Study in Rural Kenya

Tungiasis (sand flea disease) is a neglected tropical disease, prevalent in resource-poor communities in South America and sub-Saharan Africa. It is caused by an inflammatory response against penetrated female sand fleas (Tunga penetrans) embedded in the skin of the host. Although associated with debilitating acute and chronic morbidity, there is no proven effective drug treatment. By consequence patients attempt to remove embedded sand fleas with non-sterile sharp instruments, such as safety pins, a procedure that represents a health threat by itself. In this proof-of-principle study we compared the topical application of a mixture of two dimeticones of low viscosity (NYDA) to the topical application of a 0.05% solution of KMnO4 in 47 school children in an endemic area in rural Kenya. The efficacy of the treatment was assessed during a follow up period of seven days using viability signs of the embedded parasites, alterations in the natural development of lesion morphology and the degree of local inflammation as outcome measures. Seven days after treatment, in the dimeticone group 78% (95% CI 67–86%) of the parasites had lost all signs of viability as compared to 39% (95% CI 28–52%) in the KMnO4 group (p<0.001). In the dimeticone group 90% (95% CI 80–95%) of the penetrated sand fleas showed an abnormal development already after 5 days, compared to 53% (95% CI 40–66%; p<0.001) in the KMnO4 group. Seven days after treatment, signs of local skin inflammation had significantly decreased in the dimeticone group (p<0.001). This study identified the topical application of dimeticones of low viscosity (NYDA) as an effective means to kill embedded sand fleas. In view of the efficacy and safety of the topical treatment with dimeticone, the mechanical extraction of embedded sand fleas using hazardous instruments is no longer warranted.     

Australian ecosystems, capricious food chains and parasitic consequences for people

Characteristic Australian ecosystems or environments contain numerous food chains some of which may become capriciously side-tracked or appropriated by humans, with parasitic consequences for people in Australia and overseas. Twelve of 13 arboviruses affecting humans are of wildlife origin and all are transmitted by mosquitoes. In this case, transmission is thus associated with aquatic environments, many artificial. Zoonotic trematode (brachylaimiasis) and cestode (rodentoleposis) infections have been reported from semi-arid environments. Scabies and angiostrongylosis are associated with work, recreational and home environments. Four species of Rickettsia endemic in wildlife are acquired by humans from fleas, mites and ticks in bush and semi-urban environments. The enigmatic and life-threatening muspiceoid nematode, Haycocknema perplexum, is known from people associated with the natural environment in Tasmania; whether it comes from vertebrates, invertebrates, plants, soil or water is unknown. Food chains occurring in a range of Australian ecosystems and environments, some associated with feeding arthropods, others with accidental ingestion of invertebrates, may result in human exposure and infection. A range of organisms normally occurring in wildlife, domestic animals or the environment may be involved in causing human disease.