Female Fleas Research Articles

Sex ratio in flea infrapopulations: number of fleas, host gender and host age do not have an effect

This study set out to determine whether the sex ratio of fleas collected from host bodies is a reliable indicator of sex ratio in the entire flea population. To answer this question, previously published data on 18 flea species was used and it was tested to see whether a correlation exists between the sex ratio of fleas collected from host bodies and the sex ratio of fleas collected from host burrows. Across species, the female:male ratio of fleas on hosts correlated strongly with the female:male ratio of fleas in their burrows, with the slope of the regression overlapping 1. Controlling for flea phylogeny by independent contrasts produced similar results. It was also ascertained whether a host individual is a proportional random sampler of male and female fleas and whether the sex ratio in flea infrapopulations depends on the size of infrapopulations and on the gender and age of a host. Using field data, the sex ratio in infrapopulations of 7 flea species parasitic on 4 rodent species was analysed. Populations of 3 species (Nosopsyllus iranus, Parapulex chephrenis and Xenopsylla conformis) were significantly female-biased, whereas male bias was found in 1 species (Synosternus cleopatrae). In general, the sex ratio of fleas collected from an individual rodent did not differ significantly from the sex ratio in the entire flea population. Neither host gender, and age nor number of fleas co-occurring on a host affected (a) the sex ratio in flea infrapopulations and (b) the probability of an infrapopulation to be either female- or male-biased.

Imported case of human tungiasis in Hungary

Tungiasis is a parasitic skin disease due to the permanent penetration of the female sand flea T. penetrans (Linnaeus, 1758) into the skin of its host. A 39-year-old male patient was observed in May 2005 at the Outpatient Department of Dermato-Venerology Szent Rókus Hospital in Budapest because he felt the sensation of a foreign body growing under the skin of his left big toe. When the lesion occurred he was at Brazilian seaside, where he often walked barefooted. 6-7 days after, at the left big toe he saw on the margin oedematous, at the centre brownish punctuated lesion, 6-7 mm in diameter. Dermatological examination showed at the medial surface of the left big toe 6 mm in diameter, prominent, pustule-like lesion with approximately 2 mm rim of hyperemia. Surgically 4 mm in diameter whitish softish sheath was extracted. At the Department of Parasitology National Center for Epidemiology, Budapest, the parasite-like form was identified as Tunga penetrans. With this case report the authors would like to call Hungarian physicians attention to this exotic disease imported into Hungary. To the best of the authors' knowledge, this is the first imported human case of tungiasis in Hungary.

Investigations on the life cycle and morphology of Tunga penetrans in Brazil

In the present study, the life cycle of Tunga penetrans was established in Wistar rats in the laboratory, and the morphology of the resulting developmental stages was studied by means of light and scanning electron microscopy. It was seen that the females enter at a nonfertilized stage through the skin of their hosts. Only there the copulation occurs, while females and males brought together in a Petri dish showed no interest in each other. In any way -- fertilized or not -- the females start about 6 days after penetration and hypertrophy with the ejection of eggs. While fertilized eggs proceed to development, the unfertilized ones remain arrested. The eggs are ovoid and measure about 600 x 320 mum. The larvae hatch from the eggs 1-6 days (mean 3-4) after ejection. Formation of larvae 2 took at least another day, while 4 up to 10 days more were needed until this larva starts pupation (mean 5-7 days). The formation of the adult fleas inside the puparium occurred within 9-15 days (with a maximum hatch at day 12). Adult female fleas having reached the skin of a host start blood sucking within 5 min and prepare to enter the skin. After 24 h, the flea stacked already with two thirds of its body inside the skin. After 40 h, the penetration was completed, and feeding and hypertrophical enlargement started, which was completed on day 6, when eggs became ejected. When studying the morphology of the fleas obtained from different hosts, slight variations were seen, which, however, are not significant for a species separation but may be an indication of the presence of different strains/races or the beginning of such a formation.

Reproductive success in two species of desert fleas: density dependence and host effect

We tested the hypothesis that a negative fitness-density relationship exists in haematophagous ectoparasites. We studied the effect of flea density on the number of blood meals necessary for starting oviposition and egg production in Xenopsylla conformis and Xenopsylla ramesis when exploiting two rodent hosts, Meriones crassus and Gerbillus dasyurus. The number of blood meals taken by a flea prior to first oviposition was similar in both flea species but was dependent on flea density and differed significantly between hosts. When parasitizing G. dasyurus, females of both flea species required a similar number of blood meals to start oviposition, independent of density. By contrast, fleas on M. crassus at higher densities needed less blood meals than at lower densities. Egg production of female fleas differed significantly between flea and host species and was affected by flea density. X. ramesis produced more eggs than X. conformis. When parasitizing G. dasyurus, density did not affect the number of eggs produced by X. conformis, however, when on M. crassus, this flea produced significantly less eggs at the highest density. The number of eggs produced by X. ramesis at high densities was significantly lower than at low densities when it parasitized either host species. Results of this study demonstrated that reproductive success of fleas was density dependent and, in general, decreased with an increase in density. However, the effect of density on reproductive performance was manifested differently on different host species.

Tungiasis and myiasis

Tungiasis and myiasis are common ectoparasitic infestations that occur in developing countries in the tropics, particularly where poverty and poor standards of basic hygiene exist. The growth in international travel to and from these regions has led to an increase in the presentation of these conditions in nonendemic countries. Despite recent progress in the treatment and prevention of tungiasis and myiasis, diagnosis can present a challenge to those unfamiliar with these conditions, especially when they present in nonendemic countries. Tungiasis is caused by the penetration of the female sand flea, Tunga penetrans, into the epidermis of the host. Myiasis is a parasitic infection of the skin and mucous membranes in which the larvae of Diptera insects penetrate healthy or altered skin depending on the species. Infestations are usually self-limited and present few complications. Social neglect and inadequate health behavior in economically depressed urban neighborhoods, however, may lead to secondary infections and complications.

Host condition and host immunity affect parasite fitness in a bird–ectoparasite system

SummaryParasites might preferentially feed on hosts in good nutritional condition as such hosts provide better resources for the parasites’ own growth, survival and reproduction. However, hosts in prime condition are also better able to develop costly immunological or physiological defence mechanisms, which in turn reduce the parasites’ reproductive success. The interplay between host condition, host defence and parasite fitness will thus play an important part in the dynamics of host–parasite systems.In a 2 × 2 design, we manipulated both the access to food in great titParus majorbroods and the exposure of the nestlings to hen fleasCeratophyllus gallinae, a common ectoparasite of hole‐breeding birds. We subsequently investigated the role of manipulated host condition, host immunocompetence, and experimentally induced host defence in nestlings on the reproductive success of individual hen flea females.The food supplementation of the nestlings significantly influenced the parasites’ reproductive success. Female fleas laid significantly more eggs when feeding on food‐supplemented hosts.Previous parasite exposure of the birds affected the reproductive success of fleas. However, the impact of this induced host response on flea reproduction depended on the birds’ natural level of immunocompetence, assessed by the phytohaemagglutinin (PHA) skin test. Flea fecundity significantly decreased with increasing PHA response of the nestlings in previously parasite‐exposed broods. No relationship between flea fitness and host immunocompetence was, however, found in previously unexposed broods. The PHA response thus correlates with the nestlings’ ability to mount immunological or physiological defence mechanisms against hen fleas. No significant interaction effect between early flea exposure and food supplementation on the parasites’ reproductive success was found.Our study shows that the reproductive success of hen fleas is linked to the hosts’ food supply early in life and their ability to mount induced immunological or physiological defence mechanisms. These interactions between host quality and parasite fitness are likely to influence host preference, host choice and parasite virulence and thus the evolutionary dynamics in host–parasite systems.

Tunga penetrans: a stowaway from around the world

Tungiasis is a cutaneous ectoparasitic infestation by the female sand flea Tunga penetrans. It is predominantly a health problem in sub-Saharan Africa, the Caribbean, Latin America and South America. However, increasing numbers of returning travellers, immigrants, and adopted children are also affected in non-tropical countries. It is a cause of substantial morbidity, with prevalence rates as high as 76% in certain endemic areas. To date, the early extraction of the flea is still the first line therapy.

Effect of herbivory by Teleonemia scrupulosa on the performance of Longitarsus bethae on their shared host, Lantana camara

Abstract Herbivory by insects may change the characteristics of nutrients and secondary plant chemicals of the foliage, thereby altering the acceptability and suitability of the plant for oviposition, feeding and development for subsequent herbivores. In the current study, the effect of herbivory by the sap-sucking lace bug, Teleonemia scrupulosa Stal (Heteroptera: Tingidae), on the suitability of Lantana camara L. (Verbenaceae) for the root-feeding flea beetle, Longitarsus bethae Savini & Escalona (Chrysomelidae: Alticinae), was investigated under laboratory conditions. Preference of adult L. bethae was not influenced by the intensity of feeding damage caused by T. scrupulosa adults. However, high densities of T. scrupulosa nymphs and their feeding damage caused L. bethae adults to emigrate and colonize less infested or uninfested plants. Oviposition by L. bethae was significantly reduced at high densities of T. scrupulosa nymphs. While low infestation of T. scrupulosa had no effect the survival of L. bethae, moderate and high infestations caused significant reduction in percentage survival of L. bethae. The number of T. scrupulosa nymphs was negatively correlated with the percentage survival of L. bethae. Neither the duration of development nor the body size of L. bethae was influenced by the intensity of T. scrupulosa infestation. Overall, undamaged or slightly damaged plants that allowed better survival of L. bethae were often chosen as oviposition sites in preference to those that were highly infested, and on which survival was poor. Although the present study indicates the likelihood of inter-specific competition between L. bethae larvae and T. scrupulosa, this is likely to be mitigated by female flea beetles choosing to oviposit on less infested or uninfested plants in the field.

Tungiasis in rural Haiti: a community-based response

Tungiasis is a disease endemic to poor communities in Latin America, the Caribbean and Africa. It is caused by the female flea, Tunga penetrans, which burrows into the skin of its host to feed while producing and extruding eggs. Consequent lesions may be painful and even crippling with damage ranging from mild erythema and swelling to necrosis. Superinfection of lesions can be serious and may result in auto-amputation or death from tetanus. We describe an outbreak of tungiasis in rural Haiti and a community-based intervention used to address it. Of 177 patients assessed, 132 (47 female, 85 male, 23 children) had tungiasis lesions. Forty-four patients had clinical signs of superinfection; 15 had ectopic lesions. Community health workers cleaned and disinfected patients' feet and any parts of the body with ectopic lesions, and then extracted fleas from existing lesions. Patients with superinfections were treated with appropriate antibiotics. Over 1000 pairs of shoes were distributed in the villages. Over 400 adults were given tetanus vaccinations during follow-up visits. Patients who had been treated reported feeling better and those who had received shoes indicated they had not developed new lesions. All superinfections were resolved. We concluded that community-based care can treat tungiasis effectively.

Tungiasis

Tungiasis is a neglected parasitic skin disease caused by the permanent penetration of the female sand flea (also called jigger flea) Tunga penetrans into the skin of its host. After penetration, most commonly on the feet, the flea undergoes an impressing hypertrophy, and some days later the abdominal segments of the flea have enlarged up to the size of about 1 cm. The flea infestation is associated with poverty and occurs in many resource-poor communities in the Caribbean, South America and Africa. In this review, a historical overview on tungiasis is given. The natural history, pathology, epidemiology, diagnosis, therapy and control of the parasitic skin disease are discussed. It is concluded that tungiasis is an important parasitosis causing considerable morbidity in affected populations. Future studies are needed to increase the knowledge on the biology, pathophysiology, epidemiology, therapy and control of the ectoparasite.

Identifying risk factors for tungiasis and heavy infestation in a resource-poor community in northeast Brazil

Tungiasis is a neglected parasitic skin disease caused by penetration of female sand fleas into the epidermis. The ectoparasitosis is widespread in resource-poor communities in South America, the Caribbean and sub-Saharan Africa. To identify risk factors for the presence of sand fleas and severe infestation in an endemic community, we examined the entire population of a traditional fishing village for the presence of embedded sand fleas and determined the number and type of lesions. Demographic, behavioural and environmental characteristics of the population were assessed using a structured questionnaire. Multivariable analysis showed that both occurrence of tungiasis and heavy infestation were significantly related to poor housing conditions (odds ratio [OR]=4.7, 95% CI 1.4-15.8), lack of health education (OR=4.1, 95% CI 2.0-8.6) and presence of animals on the compound (OR=1.9, 95% CI 1.1-3.4). Contrary to common belief, a protective effect of frequent use of closed footwear could not be demonstrated. Based on the population attributable fractions calculated for the major risk factors identified, we conclude that several low-cost interventions would have a considerable impact on the occurrence of tungiasis and heavy infestation.

Energy costs of blood digestion in a host-specific haematophagous parasite

Fleas consume and digest blood from their hosts. We hypothesized that the energy costs of digestion of blood by fleas is dependent on the host species. To test this hypothesis, we studied CO2 emission, a measure of energy expenditure, during digestion of a blood meal taken by Parapulex chephrenis from a preferred (Acomys cahirinus) and a non-preferred (Gerbillus dasyurus) host. We predicted that the energy cost of digestion would be lower for A. cahirinus blood than that for G. dasyurus. Male and female fleas consumed similar amounts of blood per unit body mass, independent of host species. Our prediction was supported in that fleas expended significantly more energy digesting blood of G. dasyurus than blood of A. cahirinus. We also found CO2 emission rates of fed fleas were higher than those of unfed fleas and differed significantly among stages of blood digestion when a flea fed on G. dasyurus but not when it fed on A. cahirinus. When fed on G. dasyurus, fleas spent less energy during earlier than later stages of digestion.

An unusual case of ectopic tungiasis with pseudoepitheliomatous hyperplasia

Tungiasis is caused by the penetration of the female sand flea Tunga penetrans into the epidermis, and subsequent hypertrophy of the parasite. In most cases lesions are confined to the feet. During a cross-sectional study, an unusual case of ectopic tungiasis in the inguinal area was detected. Histological examination of tissue samples showed a remarkable pseudoepitheliomatous aspect of the epidermis. Clinical features and differential diagnoses are discussed.

Investigations on the biology, epidemiology, pathology and control of Tunga penetrans in Brazil. V. Cytokine concentrations in experimentally infected Wistar rats

Tungiasis is caused by the penetration of the female sand flea Tunga penetrans into the skin of its host. This parasitic skin disease is almost invariably associated with an intense inflammation around embedded fleas, the underlying mechanisms being unknown. A study was undertaken to determine whether Wistar rats can be used as an animal model to assess cytokine kinetics during the natural course of the infection. Laboratory-raised Wistar rats were exposed in cages put on the soil in an area with high human attack rates. Rats were examined daily and blood samples were taken before exposure and at 2, 6, 10, 13, 16 and 20 days after flea penetration. TNF-alpha, IL-1 beta, IFN-gamma, IL-4, IL-10 and CINC (a rat cytokine- induced neutrophil chemoattractant and member of the IL-8 family) were determined by enzyme immunoassay. The results showed an increasing serum concentration of TNF-alpha and IL-1 beta 10-13 days after penetration and a rapid increase in IL-4 2 days after fleas became embedded. During the natural course of the infection, the ratio of the serum concentration of TNF-alpha to that of IL-10 decreased, indicating a relative increase in the secretion of the anti-inflammatory cytokine. The treatment of lesions with silicone oil abrogated the natural disease course and changed the pattern of cytokine secretion. We conclude that the Wistar rat is an appropriate model to study immune responses in tungiasis.

High infection rate of Wolbachia endobacteria in the sand flea Tunga penetrans from Brazil

Tunga penetrans is an ectoparasite causing considerable morbidity in endemic communities. Recently, endobacteria of the genus Wolbachia were identified also in T. penetrans. Since Wolbachia were suggested as targets for intervention of insect pests and human filariasis, sand fleas were collected from infested humans, dogs and rats in a hyperendemic area in northeastern Brazil, and screened for Wolbachia infections. Twenty-one adult fleas and four batches of flea eggs were examined by PCR using primers targeting the 16S rDNA, the DNA coding for FtsZ cell-cycle protein or a Wolbachia surface protein (WSP-1). Wolbachia were detected in all examined samples from eggs, free-living male and female fleas and from neosomic female fleas. No Wolbachia DNA was detected in two samples containing flea faeces. In addition, Wolbachia were labelled by immunohistology in the ovaries of 37 female fleas using antisera raised against WSP-1 of Wolbachia the filarial parasite Dirofilaria immitis. In the vicinity of the embedded fleas containing the Wolbachia, infiltrations of neutrophils and macrophages were observed. This study showed that Wolbachia endobacteria are abundant in T. penetrans and that all examined fleas were infected by these endobacteria. Our findings may have important implications for the future development of control strategies for human tungiasis.

Metabolic rate and jump performance in seven species of desert fleas

We hypothesized that sexual and interspecific differences in jumping performance of fleas found in our previous study are correlated with differences in resting metabolic rate (RMR) between sexes and among species. To test this hypothesis, we measured RMR of seven flea species ( Xenopsylla conformis mycerini, Xenopsylla ramesis, Xenopsylla dipodilli, Parapulex chephrenis, Synosternus cleopatrae pyramidis, Nosopsyllus iranus theodori and Stenoponia tripectinata medialis). We compared RMR between sexes and among species and examined whether there is intra- and interspecific correlation between RMR and jumping ability. Both mass-specific and mass-independent RMR were the highest in female S. t. medialis, whereas mass-specific RMR was the lowest in male X. dipodilli and mass-independent RMR was the lowest in three Xenopsylla species and P. chephrenis. Mass-specific and mass-independent RMR were significantly higher in females than in males in all fleas except S. t. medialis. Differences in jumping ability between males and females were found to be correlated with sexual differences in mass-specific or mass-independent RMR. Interspecific comparison showed that the length of jump in both male and female fleas was strongly affected by their mass-specific and mass-independent RMR.

Action spectra of phototactic responses of the flea beetle, Phyllotreta striolata

Abstract. Adult flea beetles, Phyllotreta striolata, show a strong positive phototactic response. The action spectrum of phototaxis of dark‐adapted beetles was measured with minimal required light intensity between the wavelength range of 300 nm and 600 nm. Male and female flea beetles showed identical phototacitc behaviours. The beetles were most sensitive to light with peak wavelengths between 350 nm and 430 nm in the morning. In the afternoon and evening, the sensitivity to wavelengths shorter than 430 nm decreased, but they remained most sensitive to 430 nm. These results suggest that changes in sensitivity of the photoreceptors or nervous integration influence the phototactic responses, and that the blue wavelengths are more attractive than others.

Sexual size dimorphism, morphological traits and jump performance in seven species of desert fleas (Siphonaptera)

AbstractJump performance was studied in seven flea species (Xenopsylla conformis mycerini, Xenopsylla ramesis, Xenopsylla dipodilli, Parapulex chephrenis, Synosternus cleopatrae pyramidis, Nosopsyllus iranus theodori and Stenoponia tripectinata medialis). Jump length was compared among individuals, between sexes and among species, and an examination made of whether: (1) there is a consistent difference in jump performance between male and female fleas; (2) sexual dimorphism in body size affects jump performance; (3) there is a size‐specific difference in jump performance among species; (4) there are morphological correlates of jumping ability among individuals, between sexes and among species. Males were smaller than females in all species and size dimorphism did not increase with increasing body size. In all species, except S. t. medialis, both absolute and size‐specific jumping abilities of the males were less than those of the females. Males and females of S. t. medialis demonstrated similar jumping ability despite their body size difference. The best jumpers were S. c. pyramidis, N. i. theodori and S. t. medialis, whereas X. dipodilli as well as female X. c. mycerini and X. ramesis demonstrated the poorest ability to jump. Female:male performance ratio differed among species, being the highest in X. c. mycerini and X. ramesis, and the lowest in S. t. medialis. The proportion of the overall dimorphism in jumping ability that was owing to size differences between males and females was low, ranging from 0.10 to 0.34. No correlation between jumping ability and pleural height or length of hind coxa, femur and tibia was found in any species, except in X. dipodilli. Interspecific comparisons using size‐corrected and phylogeny‐controlled values did not show any relationship between jumping ability and any morphological trait. Fleas occupying habitats with a soft sandy substrate were better jumpers than those living in habitats with a hard stony substrate.

RV014 Q-fever — Epidemiology and control

Four hundred and sixty seven Ctenocephalides felis fleas removed from 185 feral cats living in residential areas of Jerusalem, Israel, were screened for bacterial infections of public health importance. The fleas were screened for bartonellae, rickettsiae and Coxiella burnetii by PCR and sequencing. Bartonella DNA was detected in 156 individual fleas collected from 91 of the 185 (49.2%) cats. DNA of Bartonella clarridgeiae, Bartonella henselae and Bartonella koehlerae was detected in 112/467 (24%), 29/467 (6.2%) and 15/467 (3.2%), respectively, indicating a significantly different distribution (P < 0.00001) of these Bartonella spp. among the fleas. However, no differences were observed between female and male fleas in their Bartonella-infection status (P > 0.05). Ninety one individual cats carried fleas infected with 1 to 3 Bartonella species. No differences were found between fleas collected from male and female, pregnant and non-pregnant or young, juvenile and adult cats. Interestingly, a significant association was observed between the clinical status of the cat hosts (apparently healthy versus sick) and the carriage of Bartonella-positive fleas. One of the 467 (0.2%) fleas was positive for Rickettsia felis DNA and no other Rickettsia spp. or C. burnetii DNA were detected. Our findings indicate a relatively high prevalence of Bartonella spp. known to be human pathogens, and low prevalence of R. felis in fleas from the Jerusalem district cats, highlighting the abundance and importance of bartonellae for public health in this urban region.

Investigations on the biology, epidemiology, pathology and control of Tunga penetrans in Brazil: III. Cytokine levels in peripheral blood of infected humans.

Tungiasis is caused by penetration of the female jigger flea, Tunga penetrans, into the skin of its host. This parasitic skin disease is almost invariably associated with intense inflammation around embedded fleas, the underlying mechanisms being unknown. A study was undertaken to determine whether the inflammatory process can be attributed to immune activation induced by a biologically active foreign body. We determined the concentrations of Th1-mediated (IFN-gamma, TNF-alpha) and Th2-mediated (IL-4) cytokines in the sera of patients with tungiasis. The results were compared with those of controls infected with different helminths or exposed to soil-transmitted helminths. The results show that tungiasis causes a mixed Th1 and Th2 immune response, characterized by significantly increased concentrations of the pro-inflammatory cytokines IFN-gamma and TNF-alpha, with a slightly increased concentration of IL-4. The preponderance of the Th1 immune response was indicated by a significantly increased TNF-alpha/IL-4 ratio in patients with tungiasis, as compared with the control groups.