Chigger Research Articles

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.

Imported tungiasis: a report of 19 cases and review of the literature

Tungiasis is an infestation caused by penetration in the skin of the gravid female of the flea Tunga penetrans. In the period 1991-2006, 19 patients with imported tungiasis were observed at our Institute. All patients were subjected to general and dermatological examination, laboratory tests (including bacteriological examinations) and surgical excision of the lesions with histopathological examination. In all patients tetanus prophylaxis was made. All patients were followed up for at least six weeks. Thirteen patients were males (68.4%) and 6 females (31.6%). The age ranged from 3 to 71 years (average age: 37.8 years). Eleven patients (57.9%) contracted the infestation in Central and South America and 8 (42.1%) in Africa. In 17 patients (89.5%) tungiasis was localized to the feet, in one to the hands and in one to a thigh. In 13 patients (68.4%) the infestation was characterized by a single lesion; in the other 6 patients (31.6%) the lesions were two. In 15 patients (78.9%) tungiasis was characterized by a papular or nodular lesion. Crusted (2 patients), pustular (2 patients) and bullous (1 patient) lesions were also observed; furthermore, one patient presented with a plantar wart-like lesion. In only one patient bacteriological examinations showed the growth of Staphylococcus aureus and Escherichia coli. All patients healed without complications.

Investigations on the biology, epidemiology, pathology and control of Tunga penetrans in Brazil. VI. Natural history of the infestation in laboratory-raised Wistar rats

Tungiasis is endemic in many countries in Latin America, the Caribbean and sub-Saharan Africa, and it is associated with severe morbidity. The pathophysiological and immunological characteristics of the ectoparasitosis are not well understood, and no effective therapy is currently available. The aim of this study was to describe the natural history of tungiasis in laboratory-raised Wistar rats. The rats were exposed in the laboratory to the parasite or were kept in a natural environment with an intense transmission of Tunga penetrans. The time course of the infestation was determined, and lesions were photographed, described clinically in detail and biopsied. Biopsies were examined histopathologically and by light and scanning electron microscopy. Based on these findings, the natural history of tungiasis in Wistar rats was described and divided in five stages. Our data show that the natural history of tungiasis in Wistar rats and humans is almost identical, except that in the animals, the basement membrane disrupts 5 days after penetration and provokes an intense infiltration of the dermis, while in humans, the basement membrane remains intact. The study indicates that the Wistar rat is an appropriate model for the study of clinical and pathological aspects of tungiasis. Using this model should enable a better understanding of the pathophysiology and immunology of the ectoparasitosis.

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.

Tungiasis: high prevalence, parasite load, and morbidity in a rural community in Lagos State, Nigeria

Tungiasis is common in resource-poor populations throughout Latin America, the Caribbean, and sub-Saharan Africa, but epidemiologic data from Africa on this ectoparasitosis are scarce. A cross-sectional study was carried out in a representative sample of a rural community in Lagos State, 54 km west of Lagos (Nigeria). In the dry season, 142 households of the community were randomly selected and visited. Family members were examined for the presence of tungiasis. The localization, number, and stage of penetrated fleas, as well as the associated morbidity, were documented. Five hundred and fifty-seven individuals were examined, 299 (53.7%) males and 258 (46.3%) females. In total, 252 (45.2%; 95% confidence interval, 41.1-49.5) were infested with Tunga penetrans. The prevalence was highest between the ages of 5 and 14 years, decreased in adults, and increased again in the elderly. There was no statistically significant difference between the prevalence in males and females (47.2% vs. 43.0%; P = 0.3). Almost 95% of lesions were localized on the feet. Ten per cent of individuals presented with sand fleas on the hands and elbows. The median parasite load was six (interquartile range, 3-16). Individuals aged 60 years or over had significantly more lesions (median of 41 lesions; P < 0.01). About one-third of the study participants found it difficult to walk; in 10% of cases, fissures were present. Superinfection was common. The prevalence of tungiasis and the parasite load were high, and the severity of the disease was considerable. The prevalence and parasite burden showed a characteristic distribution. In western Nigeria, tungiasis needs to be regarded as an important public health problem.

INFESTATION OF WISTAR RATS WITH TUNGA PENETRANS IN DIFFERENT MICROENVIRONMENTS

Tungiasis is a zoonotic ectoparasitosis that causes considerable morbidity in affected populations. The type of microenvironment that facilitates infestation of hosts by Tunga penetrans has not been investigated. In this study, we exposed 30 laboratory-raised Wistar rats, a suitable model for the infestation, at six different places characterized by different microenvironments in a hyperendemic fishing village in northeastern Brazil. During a period of two weeks, the animals were monitored and the number of embedded fleas was documented. The number of lesions varied considerably according to the microenvironment and was highest in a cage placed at the far end of a compound of a household affected by tungiasis. No penetration was observed inside houses. Results indicate that in this endemic area transmission of T. penetrans seems to occur mainly outdoors.

Synonymy of the sand-mite genus Straelensia with the genus Liuella (Acariformes: Trombiculoidea)

The sand-mite genus Liuella Wang & Bai, 1992 was erected in the tribe Trombiculini, subfamily Trombiculinae, family Trombiculidae. It was characterized by the rounded shield-shaped peniscutum (PSc) without an anteromedian projection (A=-), with 1AM and 2ALs; 2PLs off the scutum (Fig. 1); fSP=7.7.7; fcx=1.2.1; sternal setae numerous, arranged in three rows; with as many as 10 ventral humeral setae on either side, and SIF=4Bs-N-3-1000.0000. The genus was defined according to a single specimen, the holotype of Liuella virtus Wang & Bai, 1992. The slide was deposited in the Entomological Museum of the Institute of Zoology at the Chinese Academy of Sciences. The validity of this genus is in question because the generic diagnosis is identical to that of Straelensia Vercammen-Grandjean & Kolebinova, 1968 of the subfamily Apoloniinae (Leeuwenhoekiidae), except that an anteromedian projection or “nasus” is present in Straelensia.

Infestação de Tunga penetrans siphonaptera: Tungidae em cascos de vacas leiteiras F1 Holandês-Zebu

Tunga penetrans rate of infestation in hooves of confined F1 Holstein-Zebu cows during the dry season was recorded. First parturition cows showed an infestation rate of 90.5% in the thorax and 96.9 in the pelvic members, second parturition cows showed an infestation rate of 95.3% in the thorax and 100% in the pelvic members while third parturition cows showed rate of infestation of 100% for both members.

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.

Tungíase: doença negligenciada causando patologia grave em uma favela de Fortaleza, Ceará

The parasitic skin disease tungiasis, caused by the jigger flea Tunga penetrans, is endemic in low-income communities in Brazil. In this study, inhabitants of a shantytown in Fortaleza, northeastern Brazil, who had an elevated parasite load, were identified. The number of lesions, localization, staging and associated diseases were recorded. The 142 individuals identified were living in extremely precarious housing conditions. A total of 3,445 lesions located on the feet were counted (median = 17 lesions; maximum = 98 lesions). Almost without exception, the individuals had nail deformation and edema, and more than 70% presented with pain and fissures. There was nail loss in 46%; deformation of the digits in 25%; abscesses in 42%; and complaints of walking difficulty in 59%. Our data show that tungiasis in this low-income urban community typical of northeastern Brazil was associated with severe morbidity. Tungiasis needs to be recognized as a public health problem in this study area and other similar endemic areas.

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.

Genetic variability of Tunga penetrans (Siphonaptera, Tungidae) sand fleas across South America and Africa

Tunga penetrans is a widely distributed sand flea, infecting men and domestic animals. It originated in South America, but it is now also endemic of Sub-Saharan Africa due to a recent accidental introduction. Previous genetic analyses indicated a very limited variability in the Ecuadorian populations; on the other hand, samples from Madagascar resulted to be genetically isolated. To better examine the genetic variability of T. penetrans, a wider sampling was analysed for mitochondrial (cytochrome oxidase II) and nuclear (ribosomal internal transcribed spacer [ITS] 2) DNA sequences. The mitochondrial marker confirms the low genetic variability, with few haplotypes characterizing the majority of individuals from different populations. Haplotype distribution is in agreement with a recent colonization of Africa and with a rapid spreading across this continent. Moreover, a consistent gene flow between the Pacific and Atlantic South American populations emerges, possibly due to human and/or animal cross-Andean dispersal. On the other hand, the ITS2 marker depicts a sharply diverging pattern with samples collected in Ecuador unequivocally distinguished from the Brazilian and African ones. On the whole, taking into account also the molecular features of the marker used, data here presented are better interpreted in the light of a high dispersal ability of T. penetrans, probably reducing the phylogeographic signal.

Morbidity assessment in sand flea disease (tungiasis)

Tungiasis, caused by the sand flea Tunga penetrans, is a health problem in many impoverished communities in Latin America, the Caribbean, and sub-Saharan Africa. Sand flea disease is associated with a broad spectrum of clinical and histological pathology. The factors determining the disease burden in endemic communities are not well understood, and severity of clinical pathology has never been assessed quantitatively. Thus, two severity scores were developed: one for acute disease and one for chronic sequels. These scores were evaluated in a cohort of 70 severely infested patients living in a shantytown in Fortaleza, a capital city in Northeast Brazil. Patients were examined during a period of 25 days and followed-up after a twice daily application of a plant-based repellent to prevent reinfestation. The severity score for acute disease symptoms significantly correlated with the infestation rate and the number of embedded fleas. It turned zero when reinfestation was prevented. The score for chronic disease also significantly correlated with the infestation rate. Tungiasis is associated with considerable acute and chronic morbidity. The degree of acute morbidity is directly related to the number of embedded sand fleas. When transmission is interrupted, the chronic morbidity reflects the infestation rates individuals have experienced in the past.

Observations on the endemicity of plague in Karatu and Ngorongoro, northern Tanzania

Commensal and field rodents and wild small carnivores were live-trapped in five villages of Karatu district and one settlement in the Ngorongoro Conservation Area in Ngorongoro district in Tanzania. Blood samples were taken and serologically tested for plague, using the Blocking ELISA technique. Some domestic dogs and cats in the Karatu villages were aseptically bled and similarly tested for plague. Fleas were collected from the examined animals and from randomly selected residential houses. A total of 241 rodents, 1 Crocidura spp, 43 dogs, 12 cats and 4 slender mongooses were involved in the survey. Of the rodents, 14.5% were infested with fleas, which comprised of Xenopsylla brasiliensis (45.8%) and Dinopsyllus lypusus (54.2%), with an overall population density of 0.2 fleas/animal. Thirty one (72.1%) of the dogs were infested with fleas, all of which were Ctenocephalides spp. Thirty five (63.3%) houses were infested with fleas whose population was composed of Ctenocephalides spp, Pulex irritans, Tunga penetrans and Echinophaga gallinacea. Infected rodents were found in all the villages while the infected dog was found at Rhotia-Kati. Nineteen (11%) of the rodents and one (2%) dog harboured specific plague antibodies. It was broadly concluded that sylvatic plague was endemic in Karatu district and Ngorongoro Conservation Area and that outbreaks of the disease can occur in the area any time if and when relevant conditions become favourable. Prompt application of appropriate preventive and control measures and survey for substantiating the status in the Lake Manyara National Park, which is adjacent to some of the infected villages, are recommended.

A plant-based repellent protects against Tunga penetrans infestation and sand flea disease

Tungiasis is a parasitic skin disease prevalent in impoverished populations in the tropics and associated with considerable morbidity. Treatment options are limited and prophylaxis has never been attempted. We assessed the effectiveness of a plant-based repellent to prevent infestation with Tunga penetrans and sand flea disease in an urban squatter settlement in Fortaleza, Northeast Brazil. Two cohorts were formed. One cohort started with the intervention while another served as control. The plant-based repellent Zanzarin ® was applied twice daily on the skin of the feet. After 4 weeks and a wash-out-phase of another 2 weeks, cross-over was performed. Study members were examined twice per week for the presence of newly embedded sand fleas. The number of viable and dead sand fleas and the total number of sand flea lesions were determined. Sentinel rats were used to assess local transmission dynamics. Outcome measures were the number of newly embedded sand fleas per individual per day, number of sand flea lesions per individual according to the stage, as well as type and degree of clinical pathology. Zanzarin ® applied twice daily on the feet reduced the number of newly embedded fleas by 92% (interquartile range 81–100%), the total number of lesions by 87% (81–98%) and reversed tungiasis-associated clinical pathology almost completely. In conclusion, in a setting in which tungiasis is an important health threat, the daily application of a plant-based repellent prevented the infestation with T. penetrans and sand flea disease.

Multiple Environmental Factor Analysis in Habitats of the Harvest Mite Neotrombicula autumnalis (Acari: Trombiculidae) Suggests Extraordinarily High Euryoecious Biology

The harvest mite Neotrombicula autumnalis (Trombiculidae) has become a great nuisance in various vegetated areas in Germany over the last 15 years. According to reports of dermatologists, this species appears to have propagated and spread significantly. Moreover, cases of severe trombidiosis or trombidiosis-like skin reactions have been noticed at unusually early times of the year. Due to the lack of scientific studies, little is known about the ecology of N. autumnalis and its distribution, and preferred habitats cannot be predicted. A four-year study was conducted to identify trombiculid foci in different areas of Bonn in order (1) to determine the timing of larvae appearance in different years, (2) to identify the factors that lead to high larvae abundances at the mite foci ('multiple factor analysis'), and (3) to develop an ecological control strategy. By means of the 'tile catch method' (TCM) which turned out to be most appropriate to collect data on the distribution and abundances of trombiculid mites, larvae of N. autumnalis were caught from mid July until the end of October/beginning of November. The distribution of the mites was patchy, supporting the hypothesis that certain factors cause a concentration in foci. Most of the mite foci had a fixed location for at least three years. Efforts to isolate nymphs and adults in larger quantities to gain knowledge about their preferred soil areas and soil depths failed. Only some nymphs of N. autumnalis could be found living 10-40 cm deep in the soil. Due to the restriction that the nymphs and adults can only rarely be isolated in the ground, the analysis of environmental factors was executed based on abundances of questing larvae on the soil surface. The detailed analysis of soil-physical, soil-chemical and meso-faunistic factors could not finally explain the unequal distribution of the mites, although the porosity of the soil had a statistically significant slight influence on the abundance of larvae, and soil pH bordered significance, also suggesting a slight influence. Furthermore, soil temperatures during the winter seasons in three subsequent years appeared too high to affect the harvest mite. The field experiments suggest that N. autumnalis and particularly its larval stages are extremely euryoecious (meaning tolerating very different environmental conditions). Further studies are necessary: additional investigations on the influence of certain abiotic environmental factors on N. autumnalis, the search for factors underlying the rhythmicity of its life cycle ('zeitgeber'), and the reasons and mechanisms for heterogeneous distribution of soil fauna in general. Ecological control of the mite is, in principle, possible but only after identifying the foci and ascertaining their approximate dimensions with the TCM. This control strategy is the most promising one, albeit very laborious, emphasising the need of further research on the ecology of the harvest mite.

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.

Revision on tungiasis: treatment options and prevention

The parasitic skin disease tungiasis occurs in many resource-poor communities in Latin America, the Caribbean and sub-Saharan Africa. The sand flea, Tunga penetrans, most commonly penetrates into the skin of the feet. Many individuals harbor a large number of embedded parasites and show significant morbidity. Standard treatment consists of surgical extraction of the flea and application of a topical antibiotic. There are no drugs available with proven effectiveness. Clinical trials performed in the last few years did not show very promising results. Thus, surgical extraction still remains the treatment of choice in patients with a low parasite load, such as tourists returning from endemic areas. Probably the best approach to reduce tungiasis-associated morbidity in heavily affected individuals is the application of a repellent to prevent the penetration of sand fleas. In the future, we should see new exciting data on the biology, epidemiology, therapy and control of tungiasis.

High exposure to Tunga penetrans (Linnaeus, 1758) correlates with intensity of infestation

Tungiasis is a parasitic skin disease widespread in resource-poor urban and rural communities in Brazil. Inhabitants of an urban slum in Northeast Brazil were examined for the presence of tungiasis lesions and followed-up twice a week for a period of three weeks. Each time the number, stages, and topographic localization of lesions were recorded on a documentation sheet. The infestation rate (number of newly embedded sand fleas per individual and day) remained stable during the observation period. The infestation rate was significantly related to the intensity of infestation (total number of lesions present) (rho = 0.70, p < 0.0001) and the proportion of viable lesions (rho = 0.28, p < 0.0001). The results indicate that in an endemic area the infestation intensity and the proportion of viable lesions can be used as a proxy to assess the exposure of individuals at risk for tungiasis. Persistently high infestation rates during the transmission season favour the use of prevention measures against invading sand fleas (such as a repellent) rather than a drug to kill already embedded parasites.

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.