Investigations on the biology, epidemiology, pathology and control of Tunga penetrans in Brazil. II. Prevalence, parasite load and topographic distribution of lesions in the population of a traditional fishing village

Tunga penetrans as a traveler's disease

Tunga penetrans are ectoparasites distributed widely. The infestations are endemic in some areas. People both from and visiting this region are susceptible to these infestations.

Tungiasis in schoolchildren in Criciúma, Santa Catarina State, South Brazil

Tungiasis is a common parasitic skin disease in Brazil, caused by the flea Tunga penetrans. We conducted a cross-sectional study to evaluate the occurrence of infestation with T. penetrans in primary schoolchildren in Criciúma, Santa Catarina State (South Brazil). In total, 917 children (6-10 years) of 68 schools were included in the study (11% of target population). Physical examination was followed by residential visits of those infested, to assess housing conditions and to interview the children's guardians. Of the 917, 15 (1.6%) children were infested with the parasite. The prevalence was twice as high in females (10 children--2.2%) as compared to males (five children--1.1%), but due to the low number of infested individuals, the difference was statistically not significant (p = 0.18). The mean number of lesions found was 1.4 per child. One child presented bacterial superinfection. Of the 15 children infested, 10 (66.7%) studied in schools built on pyritiferous soil. The families of 12 children (79.9%) had been living in the area in which the study was conducted for less than eight years and were considered underprivileged families with the head of the household having a low education status. We conclude that in Criciúma tungiasis occurs in primary school children, but prevalence and parasite load are low.

[Tungiasis and myiasis]

Tungiasis (sand flea disease) and myiasis are ectoparasitoses, in which the infectious agent resides temporarily in the skin (myiasis) or dies and is eventually eliminated (tungiasis). Both diseases are zoonoses. Whereas in myiasis humans are only an accidental host, in tungiasis the prevalence in humans is similar to that of their domestic animals. In travellers returning from the tropics tungiasis and myiasis are not rare, however they are frequently misdiagnosed. The diagnosis of both infestations is made clinically, and laboratory investigations are not helpful. In tungiasis the clinical picture depends on the stage of the disease. A heavy local inflammation and bacterial superinfection are frequent. Therapy consists in the complete elimination of the parasite. The repellent Zanzarin effectively protects against sand fleas.

Controlling tungiasis in an impoverished community: an intervention study

Background

In Brazil, tungiasis is endemic in some resource-poor communities where various domestic and sylvatic animals act as reservoirs for this zoonosis. To determine the effect of control measures on the prevalence and intensity of infestation of human and animal tungiasis, a repeated cross-sectional survey with intervention was carried out.

Methodology/Principal Findings

In a traditional fishing community in Northeast Brazil, humans and reservoir animals were treated, and premise-spraying using an insecticide was done, while a second fishing community served as a control. Both communities were followed up 10 times during a 12-month period. At baseline, prevalence of tungiasis was 43% (95% confidence interval [CI]: 35%–51%) and 37% (95% CI: 31%–43%) in control and intervention villages, respectively. During the study, prevalence of tungiasis dropped to 10% (95% CI: 8%–13%; p<0.001) in the intervention village, while the prevalence remained at a high level in the control village. However, after one year, at the end of the study, in both communities the prevalence of the infestation had reached pre-intervention levels. Whereas the intensity of infestation was significantly reduced in the intervention community (p<0.001), and remained low at the end of the study (p<0.001), it did not change in the control village.

Conclusion/Significance

Our study shows that a reduction of prevalence and intensity of infestation is possible, but in impoverished communities a long-lasting reduction of disease occurrence can only be achieved by the regular treatment of infested humans, the elimination of animal reservoirs, and, likely, through environmental changes.

Trial Registration

Controlled-Trials.com ISRCTN27670575

Tungiasis is a disease caused by the sand flea Tunga penetrans, a parasite prevalent in many impoverished communities in developing countries. The female sand flea penetrates into the skin of animals and humans where it grows rapidly in size, feeds on the host's blood, produces eggs which are expelled into the environment, and eventually dies in situ. The lesions become frequently superinfected and the infestation is associated with considerable morbidity. Clearly, tungiasis is a neglected disease of neglected populations. We investigated the impact of a package of intervention measures targeted against on-host and off-host stages of T. penetrans in a fishing community in Northeast Brazil. These measures decreased disease occurrence only temporarily, but had a sustained effect on the intensity of the infestation. Since infestation intensity and morbidity are correlated, presumably the intervention also lowered tungiasis-associated morbidity. Control measures similar to the ones used in this study may help to effectively control tungiasis in impoverished communities.

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.

Investigations on the biology, epidemiology, pathology, and control of Tunga penetrans in Brazil: VII. The importance of animal reservoirs for human infestation

In Brazil tungiasis is endemic in many resource-poor communities, where various domestic and sylvatic animals act as reservoirs for this zoonosis. To determine the role of animal reservoirs in human tungiasis, a cross-sectional study was performed in a traditional fishing community in northeast Brazil. The human and the animal populations were examined for the presence of embedded sand fleas and the prevalence and the intensity of infestation were correlated. The overall prevalence of tungiasis in humans was 39% (95% CI 34-43%). Of six mammal species present in the village, only cats and dogs were found infested. The prevalence in these animals was 59% (95% CI 50-68%). In households, where infested pet animals were present, a higher percentage of household members had tungiasis (42% [95% CI 30-53%] versus 27% [20-33%], p=0.02), and the intensity of the infestation was higher (six lesions versus two lesions, p=0.01). The intensity of infestation in animals correlated with the intensity of infestation in humans (rho=0.3, p=0.02). Living in a household with an infested dog or cat led to a 1.6-fold (95% CI 1.1-2.3, p=0.015) increase in the odds for the presence of tungiasis in household members in the bivariate analysis and remained a significant risk factor in the multivariate regression analysis. The study shows that in this impoverished community tungiasis is highly prevalent in humans and domestic animals. In particular, it underlines the importance to include animals in control operation aiming at the reduction of disease occurrence in the human population.

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.

Risk factors for tungiasis in Nigeria: identification of targets for effective intervention

BACKGROUND

The parasitic skin disease tungiasis (caused by the flea Tunga penetrans) affects resource-poor communities in Latin America, the Caribbean and sub-Saharan Africa. Prevalences in endemic areas are high, and severe pathology occurs commonly. However, risk factors for infestation have never been assessed in Africa.

METHODS AND FINDINGS

A cross-sectional study was conducted in Erekiti, a rural community in Lagos State (Nigeria), where tungiasis is endemic. Individuals were examined clinically for the presence of tungiasis, and a questionnaire was applied. Data from 643 individuals (86.6% of the target population) were analyzed; 252 (42.5%) were infested with T. penetrans. In the multivariate logistic regression analysis, presence of pigs on the compounds (adjusted odds ratio = 17.98; 95% confidence interval: 5.55-58.23), sand or clay floor inside houses (9.33; 5.06-17.19), and having the common resting place outside the house (7.14; 4.0-14.29) were the most important risk factors identified. The regular use of closed footwear (0.34; 0.18-0.62) and the use of insecticides indoors (0.2; 0.05-0.83) were protective against infestation. The population attributable fractions associated with tungiasis were: sand or clay floor inside the house (73.7%), resting usually outside the house (65.5%), no regular use of closed footwear (51.1%), and pigs on the compound (37.9%).

CONCLUSION

The presence of tungiasis in Erekiti is determined to an important extent by a limited number of modifiable variables. Effective and sustainable intervention measures addressing these factors need to be implemented in this and other West African communities with high disease burden.

Upper eyelid localisation of Tunga penetrans

PURPOSE

This report describes two cases of palpebral localisation of Tunga penetrans.

METHODS

Two Congolese patients (a 17-year-old black man and a 12-year-old black girl) presented with a history of itching and oedema of the left upper eyelid.

RESULTS

On inspection and slit lamp examination, the patients manifested the characteristic lesion of a white translucent papule with a central black pit. Scraping of the lesion revealed a gravid adult female flea, allowing the diagnosis of infection with the flea T. penetrans. After removal of the parasite, a complete local recovery occurred over a 1-week period with local application of tetracycline.

CONCLUSION

With the increase in international travelling, it is useful to know that eyelid localisation of T. penetrans is possible.

Cutaneous larva migrans and tungiasis in international travelers exiting Brazil: an airport survey

BACKGROUND

Hookworm-related cutaneous larva migrans (CLM) and tungiasis are commonly diagnosed in travelers returning from endemic areas, but reliable data on disease occurrence do not exist. To describe the occurrence of CLM and tungiasis in international travelers, a cross-sectional study was done.

METHOD

We conducted an airport survey in European travelers exiting northeast Brazil. Questionnaires were distributed at the departure gate of the international airport of Fortaleza (Ceará State) while passengers were waiting to board their plane. The questionnaire included questions on personal characteristics, pretravel health advice, acquired parasitic skin diseases during their stay in Brazil, and clinical characteristics of the infestation. To help identify CLM and tungiasis, photographs of the typical appearances of the infestations were presented.

RESULTS

Data from 372 tourists (aged 16-76 y, median = 40 y) were available for analysis; 45% had obtained pretravel health advice, usually from travel clinics (46.2%) and Internet sites (39.6%). Only 14% of those who obtained advice had been informed about CLM as a travel health risk and 22% about tungiasis. During their stay in Brazil, 12 (3.2%) tourists had experienced tungiasis and 3 (0.8%) CLM. In all cases, lesions were confined to the feet. The three travelers with CLM complained of irritability; itching was present in two cases. Pain (58.3%) and itching (50%) were the most common symptoms in travelers with tungiasis. The length of stay was a clear predictor for tungiasis, with a 20 times higher occurrence in travelers who had stayed for more than 4 weeks in Brazil.

CONCLUSIONS

Tungiasis and CLM are not rare in international tourists departing from Brazil, and pretravel counseling is insufficient. Pretravel health advice should include information on the risk of acquiring tungiasis and CLM and how to prevent an infestation. Airport surveys using questionnaires can be used to obtain incidence data on both parasitic infestations.

[Imported case of human tungiasis in Hungary]

INTRODUCTION

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.

CASE REPORT

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.

CONCLUSION

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 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.

[Tungiasis: a neglected disease causing severe morbidity in a shantytown in Fortaleza, State of 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.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

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.

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.

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.

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.

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 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.

Leukocytosis and blood eosinophilia in a polyparasitised population in north-eastern Brazil

It has long been known that leukocytosis and blood eosinophilia are common in the tropical environment, but data derived from population-based studies are scarce. A study was undertaken in a fishing village in north-east Brazil where both intestinal helminthiases and parasitic skin diseases are common. Of 409 individuals studied, 128 (31.3%) were infected with one intestinal helminth or ectoparasite species, 93 (22.7%) with two, 61 (14.9%) with three, 25 (6.1%) with four and 11 (2.7%) with more than four species; no parasites were found in 91 (22.2%) individuals. Leukocyte counts ranged between 3,300 cells/microl and 16,100 cells/microl (median, 7,200 cells/microl) and eosinophil counts between 40 cells/microl and 5,460 cells/microl (median, 455 cells/microl). Eosinophilia (>500/microl) was detected in 44.7% of the individuals, and hypereosinophilia (>1,000/microl) in 12.9%. Thirty-six (8.8%) individuals showed leukocytosis. While 75% of individuals with normal eosinophil counts were considered parasite-free, only 14% with eosinophilia and 11% with hypereosinophilia did not have enteroparasites or ectoparasites. Multivariate regression showed that the probability of eosinophilia and hypereosinophilia, but not of leukocytosis, increased with the number of parasite species present. The data show that eosinophilia occurs in almost one-half of the individuals from a resource-poor setting and that it is significantly associated with the presence of intestinal helminths, but not with the presence of ectoparasites.

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.

Epidemiology and morbidity of scabies and pediculosis capitis in resource-poor communities in Brazil

BACKGROUND

Pediculosis capitis and scabies are common parasitic skin diseases, especially in resource-poor communities, but data on epidemiology and morbidity are scanty.

OBJECTIVES

To assess the prevalence, seasonal variation and morbidity of pediculosis capitis and scabies in poor neighbourhoods in north-east Brazil.

METHODS

The study comprised cross-sectional surveys of a representative population of an urban slum (n = 1460) in Fortaleza, the capital of Ceará State (Brazil) and a fishing community 60 km south of the city (n = 605). Study participants were examined for the presence of scabies and pediculosis capitis. In a longitudinal study in the slum, variation of prevalence in different seasons of the year was assessed.

RESULTS

Prevalence of pediculosis capitis was 43.4% in the slum and 28.1% in the fishing community. Children aged 10-14 years and females were most frequently affected. Scabies was present in 8.8% of the population in the slum and in 3.8% of the population in the fishing community. There was no consistent pattern of age distribution. Superinfection was common in patients with scabies, and cervical lymphadenopathy in patients with pediculosis capitis. Multivariate analysis showed that age < or = 15 years, being of female sex and living in the urban slum were independent factors contributing to the simultaneous coinfestation with pediculosis capitis and scabies. The longitudinal data from the urban slum showed a characteristic seasonal variation of pediculosis capitis, but no fluctuation of scabies.

CONCLUSIONS

Pediculosis capitis and scabies are hyperendemic in the study areas and are associated with considerable morbidity. There is an urgent need to develop control measures for these parasitic skin diseases in resource-poor communities. This is the first community-based study describing in detail the epidemiology and morbidity of scabies and head lice infestation in Brazil.

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.

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.

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.

High attack rate of Tunga penetrans (Linnaeus 1758) infestation in an impoverished Brazilian community

Tungiasis (jigger) is endemic in many impoverished communities in many parts of Brazil. Forty-seven individuals entering an endemic area were followed up for a period of six weeks and regularly examined for the presence of newly embedded sand fleas. At the end of the third week, the attack rate of Tunga penetrans infestation had already approached 100%.

Investigations on the biology, epidemiology, pathology and control of Tunga penetrans in Brazil: IV. Clinical and histopathology

Tungiasis is a parasitic skin disease caused by the sand flea Tunga penetrans. This ectoparasitosis is endemic in South America, the Caribbean and sub-Saharan Africa, where it is an important but neglected health problem in resource-poor communities. As part of a study of tungiasis-related morbidity in a typical slum in Fortaleza, Brazil, we identified 86 individuals with tungiasis. Lesions were counted, classified according to the stage of development, and clinical pathology was documented. One hundred and nine lesions were biopsied and examined by histological sectioning. The patients had between 1 and 145 lesions (median 14.5), the majority occurring in clusters. In all, 77% of patients reported severe pain at the site of the lesion, and 52% had one or more nails lost or severely deformed. Intense inflammation and/or fissures hindered 45% of the patients from walking normally. Signs of superinfection were observed in 29%, and signs of generalized inflammation in 2% of patients. Clinical pathology was significantly related to the number of lesions, and the total number of parasites present correlated with the number of fleas occurring in clusters. Clinical pathology was frequently accompanied by a pathological alteration of the epidermis (predominantly hyperplasia, parakeratosis, hyperkeratosis, and spongiosis) and the dermis. Tungiasis causes a broad spectrum of clinical histopathological alterations, and is a serious health threat in a typical, impoverished community in northeast Brazil. The clinical pathology is closely related to the parasite burden of an individual and the clustering of embedded fleas at certain predilection sites.

Ectoparasites--the underestimated realm

CONTEXT

Ectoparasitoses (infestations with parasites that live on or in the skin) can cause considerable morbidity. Whereas pediculosis and scabies are ubiquitous, cutaneous larva migrans and tungiasis (sand-flea disease) occur mainly in hot climates. The prevalence of ectoparasitoses in the general population is usually low, but can be high in vulnerable groups. Scientific knowledge on how to deal best with parasitic skin diseases in different settings is scanty, and evidence-based measures for control are not available. For head lice and scabies the situation is daunting, because resistance of Pediculus humanus capitis and Sarcoptes scabiei to insecticides is spreading and unpredictable.

STARTING POINT

J Hunter and S Barker reported different patterns of resistance in schoolchildren in Brisbane, Australia: full resistance to malathion, permethrin, and pyrethrum in two schools, whereas head lice were susceptible to malathion and, to a lesser extent, to pyrethrums in three other schools (Parasitol Res 2003; 90: 476-78). K Yoon and colleagues found different resistance patterns in the USA and Ecuador (Arch Dermatol 2003; 139: 994-1000). Head lice from Florida were less susceptible to permethrin than those from Texas, and parasites from Ecuador were susceptible to both insecticides tested. WHERE NEXT? The occurrence of resistant pediculosis and scabies is expected to increase numerically and geographically. Clinicoepidemiological studies are urgently needed to identify the factors which govern the emergence and spread of strains of P humanus capitis and S scabiei that are resistant to insecticide or acaricide. Oral treatment with ivermectin could substitute for topically applied compounds, particularly in resource-poor communities where polyparasitism is common. A better understanding of local epidemiology is required to develop control measures. This knowledge has to be applied in combination with environmental sanitation, health education, and culturally acceptable interventions that are affordable by the underprivileged.

Tungiasis: more than an exotic nuisance

Tungiasis is a parasitic and zoonotic skin disease caused by the sand flea Tunga penetrans-also called the jigger flea, which burrows into human skin, usually on the feet. The ectoparasitosis occurs in many economically depressed communities in the Caribbean, South America and Africa, and affects sporadically travellers to endemic areas. Usually, only one or two lesions are found in travellers, whereas the local populations commonly harbour dozens, sometimes even hundreds of lesions, associated with severe morbidity. We review case reports of tungiasis in returned travellers in terms of history, epidemiological and clinical aspects, and the importance of the ectoparasitosis for travel medicine is discussed. It is concluded that tungiasis is more than merely an exotic nuisance, since it is an important health problem in endemic areas. Untrained dermatologists can diagnose and treat tungiasis properly; fleas should be extracted as early as possible to avoid secondary infections.