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

Prevalence and Infection Intensity of Human and Animal Tungiasis in Napak District, Karamoja, Northeastern Uganda

Tungiasis is an important but highly neglected cause of morbidity in resource-poor communities in Latin America and sub-Saharan Africa. Data upon which implementation of control measures can be based are scarce. Before piloting an integrated tungiasis control program in three parishes of Napak district, Uganda, a cross-sectional survey involving the systematic examination of humans and domestic mammals was implemented to establish the occurrence patterns of tungiasis. The study population was 5482 residents, of which 4035 (73.6%) participated in the study. The prevalence of tungiasis in humans was 62.8% (95% CI: 61.3-64.3%), with slightly more males than females affected (p = 0.01). Age-specific prevalence and intensity of human tungiasis followed an S-curve pattern, with children of 5-14 years and the elderly (≥60 years) being the most affected. Half of all lesions (50%) had been manipulated by sharp objects. The prevalence of tungiasis in animals was lower (14.2%, 95% CI: 10.9-18.0) than that of humans (p < 0.001). Animal tungiasis occurred in decreasing order of frequency in pigs (80%), dogs (24%), goats (16.3%), cats (8.1%) and sheep (4.9%). In conclusion, human tungiasis was highly prevalent but animal infections were comparatively few in the study area. Nevertheless, effective control measures should be based on One Health principles.

Current status of the knowledge on the epidemiology of tungiasis in the Americas

Objectives.

To present the state-of-the-knowledge on the epidemiology of tungiasis in the Region of the Americas.

Methods.

A search of publications on the epidemiology of tungiasis in the Americas was performed in PubMed and LILACS databases from January 2007 to June 2021. In addition, a manual literature search on articles on the epidemiology of tungiasis was performed.

Results.

A total of 83 articles were analyzed which contained relevant information on tungiasis cases and their geographical distribution, prevalence and risk factors, life cycle, sites where transmission takes place, and zoonotic aspects. The on-host and off-host life cycles have been researched in detail. In certain contexts, the whole life cycle is completed indoors enabling transmission around the whole year. Cases were reported from 10 countries; 71% of them were from Brazil. In the general population, the prevalence varied between 1.0% and 82.6% according to the settings. Age-specific prevalence indicated that children and the elderly bear the highest disease burden. Risk factor studies indicate that tungiasis is associated with severe poverty.

Conclusions.

In the Americas, there are important gaps in information and knowledge of tungiasis. Understanding the burden, epidemiology, distribution, magnitude, related risk factors, and reservoirs, among others, is needed to develop and implement integrated control measures tailored to the context and patterns of transmission in the affected communities.

Efficacy and safety of dimeticones in the treatment of epidermal parasitic skin diseases with special emphasis on tungiasis: an evidence-based critical review

Epidermal parasitic skin diseases encompass scabies, pediculosis, cutaneous larva migrans, myiasis, and tungiasis. Tungiasis is probably the most neglected of all Neglected Tropical Diseases (NTD). It occurs in South America, the Caribbean and Sub-Saharan Africa and affects marginalized populations where people live in extreme poverty. In endemic communities the prevalence can be up to 30% in general population and 85% in children. Over time, chronic pathology develops characterized by hyperkeratosis, edema around the nail rim, fissures, ulcers, deformation and loss of nails. This leads to a pattern of disabilities, eventually resulting in impairment of mobility.

Dimeticones are a family of silicon oils with a potential to kill parasites located on top or inside the epidermis by a physical mode of action. They are considered the treatment of choice for pediculosis capitis and pediculosis pubis. With regard to tungiasis, the so called rear abdominal cone of the parasites has been identified as a target for treatment with dimeticones. NYDA®, a mixture of two dimeticones with different viscosity, is the only dimeticone product for which data on the mode of action, efficacy and safety with regard to tungiasis exists. The product has been shown highly effective against embedded sand fleas, even in very intense infection with more than 500 parasites situated on top of each other. A randomized controlled trial showed that seven days after a targeted application of NYDA® 97% (95% CI 94–99%) of the embedded sand fleas had lost all signs of viability.

Comprehensive toxicological investigations on the dimeticones contained in NYDA® showed that there is practically no risk of embryotoxicity, fetotoxicity, teratogenicity, and other toxicity. The safety of dimeticones was also demonstrated in clinical trials with a total of 106 participants with tungiasis, in which not a single adverse event was observed.

Tungiasis-related life quality impairment in children living in rural Kenya

BACKGROUND

Tungiasis (sand flea disease) is a neglected tropical skin disease caused by female sand fleas (Tunga spp.) embedded in the skin of the host. The disease is common in sub-Saharan Africa and predominantly affects children living in impoverished rural communities. In these settings tungiasis is associated with important morbidity. Whether tungiasis impairs life quality has never been studied.

METHODS

The study was performed in 50 children with tungiasis, living in resource-poor communities in coastal Kenya. Based on the Dermatology Life Quality Index (DLQI) a tool was developed to determine life quality impairment associated with tungiasis in children, the tungiasis-related Dermatology of Life Quality Index (tungiasis-related-DLQI). Pain and itching were assessed using visual scales ranging from 0-3 points. The intensity of infection and the acute and chronic severity of tungiasis were determined using standard methods.

RESULTS

Seventy eight percent of the patients reported a moderate to very large effect of tungiasis on life quality at the time of the diagnosis. The degree of impairment correlated with the number of viable sand fleas present in the skin (rho = 0.64, p < 0.001), the severity score of acute clinical pathology (rho = 0.74, p < 0.001), and the intensity of pain (rho = 0.82, p < 0.001). Disturbance of sleep and concentration difficulties were the most frequent restriction categories (86% and 84%, respectively). Four weeks after curative treatment, life quality had improved significantly. On the individual level the amelioration of life quality correlated closely with the regression of clinical pathology (rho = 0.61, p < 0.001).

CONCLUSION

The parasitic skin disease tungiasis considerably impairs life quality in children in rural Kenya. After effective treatment, life quality improves rapidly.

Prevalence, intensity and risk factors of tungiasis in Kilifi County, Kenya: I. Results from a community-based study

BACKGROUND

Tungiasis is a neglected tropical disease caused by female sand fleas (Tunga penetrans) embedded in the skin. The disease is associated with important morbidity. Tungiasis is endemic along the Coast of Kenya with a prevalence ranging from 11% to 50% in school-age children. Hitherto, studies on epidemiological characteristics of tungiasis in Africa are scanty.

METHODS

In a cross-sectional study 1,086 individuals from 233 households in eight villages located in Kakuyuni and Malanga Sub-locations, Kilifi County, on the Kenyan Coast, were investigated. Study participants were examined systematically and the presence and severity of tungiasis were determined using standard methods. Demographic, socio-economic, environmental and behavioral risk factors of tungiasis were assessed using a structured questionnaire. Data were analyzed using bivariate and multivariate regression analysis.

RESULTS

The overall prevalence of tungiasis was 25.0% (95% CI 22.4-27.5%). Age-specific prevalence followed an S-shaped curve, peaking in the under-15 year old group. In 42.5% of the households at least one individual had tungiasis. 15.1% of patients were severely infected (≥ 30 lesions). In the bivariate analysis no specific animal species was identified as a risk factor for tungiasis. Multivariate analysis showed that the occurrence of tungiasis was related to living in a house with poor construction characteristics, such as mud walls (OR 3.35; 95% CI 1.71-6.58), sleeping directly on the floor (OR 1.68; 95% CI 1.03-2.74), the number of people per sleeping room (OR = 1.77; 95% CI 1.07-2.93) and washing the body without soap (OR = 7.36; 95% CI 3.08-17.62). The odds of having severe tungiasis were high in males (OR 2.29; 95% CI 1.18-44.6) and were very high when only mud puddles were available as a water source and lack of water permitted washing only once a day (OR 25.48 (95% CI 3.50-185.67) and OR 2.23 (95% CI 1.11-4.51), respectively).

CONCLUSIONS

The results of this study show that in rural Kenya characteristics of poverty determine the occurrence and the severity of tungiasis. Intra-domiciliary transmission seems to occur regularly.

Secondary bacterial infections and antibiotic resistance among tungiasis patients in Western, Kenya

Tungiasis or jigger infestation is a parasitic disease caused by the female sand flea Tunga penetrans. Secondary infection of the lesions caused by this flea is common in endemic communities. This study sought to shed light on the bacterial pathogens causing secondary infections in tungiasis lesions and their susceptibility profiles to commonly prescribed antibiotics. Participants were recruited with the help of Community Health Workers. Swabs were taken from lesions which showed signs of secondary infection. Identification of suspected bacteria colonies was done by colony morphology, Gram staining, and biochemical tests. The Kirby Bauer disc diffusion test was used to determine the drug susceptibility profiles. Out of 37 participants, from whom swabs were collected, specimen were positive in 29 and 8 had no growth. From these, 10 different strains of bacteria were isolated. Two were Gram positive bacteria and they were, Staphylococcus epidermidis (38.3%) and Staphylococcus aureus (21.3%). Eight were Gram negative namely Enterobacter cloacae (8.5%), Proteus species (8.5%), Klebsiellla species (6.4%), Aeromonas sobria (4.3%), Citrobacter species (4.3%), Proteus mirabillis(4.3%), Enterobacter amnigenus (2.1%) and Klebsiella pneumoniae (2.1%). The methicillin resistant S. aureus (MRSA) isolated were also resistant to clindamycin, kanamycin, erythromycin, nalidixic acid, trimethorprim sulfamethoxazole and tetracycline. All the Gram negative and Gram positive bacteria isolates were sensitive to gentamicin and norfloxacin drugs. Results from this study confirms the presence of resistant bacteria in tungiasis lesions hence highlighting the significance of secondary infection of the lesions in endemic communties. This therefore suggests that antimicrobial susceptibility testing may be considered to guide in identification of appropriate antibiotics and treatment therapy among tungiasis patients.

Animal Reservoirs of Zoonotic Tungiasis in Endemic Rural Villages of Uganda

BACKGROUND

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

METHODS AND FINDINGS

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

CONCLUSION

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

Prevention of tungiasis and tungiasis-associated morbidity using the plant-based repellent Zanzarin: a randomized, controlled field study in rural Madagascar

Background

Tungiasis, a parasitic skin disease caused by the female sand flea Tunga penetrans, is a prevalent condition in impoverished communities in the tropics. In this setting, the ectoparasitosis is associated with important morbidity. It causes disfigurement and mutilation of the feet. Feasible and effective treatment is not available. So far prevention is the only means to control tungiasis-associated morbidity.

Methodology

In two villages in Central Madagascar, we assessed the efficacy of the availability of closed shoes and the twice-daily application of a plant-based repellent active against sand fleas (Zanzarin) in comparison to a control group without intervention. The study population was randomized into three groups: shoe group, repellent group and control group and monitored for ten weeks. The intensity of infestation, the attack rate and the severity of tungiasis-associated morbidity were assessed every two weeks.

Findings

In the repellent group, the median attack rate became zero already after two weeks. The intensity of the infestation decreased constantly during the observation period and tungiasis-associated morbidity was lowered to an insignificant level. In the shoe group, only a marginal decrease in the intensity of infestation and in the attack rate was observed. At week 10, the intensity of infestation, the attack rate and the severity score for acute tungiasis remained significantly higher in the shoe group than in the repellent group. Per protocol analysis showed that the protective effect of shoes was closely related to the regularity with which shoes were worn.

Conclusions

Although shoes were requested by the villagers and wearing shoes was encouraged by the investigators at the beginning of the study, the availability of shoes only marginally influenced the attack rate of female sand fleas. The twice-daily application of a plant-based repellent active against sand fleas reduced the attack to zero and lowered tungiasis-associated morbidity to an insignificant level.

Tungiasis (sand flea disease) is a parasitic skin disease present in many resource-poor communities in South America, the Caribbean and sub-Saharan Africa. In this setting tungiasis is associated with important morbidity. Hitherto, the only effective treatment is the surgical extraction of embedded sand fleas. In the endemic areas this is done using inappropriate sharp instruments and causes more harm than good. The prevention of the infestation is the only option to control morbidity. In this study we show that the twice daily application of a herbal repellent based on coconut-oil (Zanzarin), is highly effective in preventing sand flea disease in a heavily affected community in Madagascar. The attack rate became zero immediately after starting the application of the repellent. The degree of tungiasis associated morbidity approached zero within 10 weeks. In contrast, the availability of closed solid shoes had only a marginal protective effect; although shoes were requested by the villagers and wearing shoes was encouraged by the investigators at the beginning of the study. In a control group from the same village the attack rate, the intensity of infestation and of tungiasis-associated morbidity remained unchanged. Our study in rural Madagascar shows that effective und sustainable morbidity control is possible using a repellent derived from coconut oil.

[The genus Tunga Jarocki, 1838 (Siphonaptera: Tungidae). I: taxonomy, phylogeny, ecology and pathogenicity]

Pour la première fois, les 12 espèces actuellement décrites dans le genre Tunga sont étudiées sur le plan de la taxonomie et de la répartition. Divers aspects de leur biologie et leur rôle pathogène sont également envisagés, et en particulier leur phylogénie, leur chorologie, leur phénologie, leur sexe-ratio et leurs dermecos.

Tungiasis (sand flea disease): a parasitic disease with particular challenges for public health

Tungiasis (sand flea disease) is caused by the penetration of females of Tunga penetrans into the skin of the feet. Within 2 weeks of penetration the burrowed flea increases its volume by a factor of 2,000. This is paralleled by intense inflammation of the surrounding tissue. Acute and chronic inflammation leads to the development of painful and debilitating clinical pathology. This results in impaired physical fitness and mobility. The social implications of tungiasis-associated morbidity are multifold. Children with tungiasis are teased and ridiculed, adults feel ashamed and stigmatized. There is anecdotal evidence that tungiasis negatively affects educational achievements. Impaired mobility and physical fitness will have a negative impact on household economics. Sand flea disease is common in resource-poor communities in South America and in sub-Saharan Africa with prevalence in the general population of up to 60%. In East Africa, it has re-emerged in epidemic dimensions in recent years. Hitherto, no effective drug treatment has been at hand. Traditional treatment, i.e., the manipulation of burrowed sand fleas with blunt and inappropriate instruments may facilitate the transmission of blood-derived pathogens. Prevention is feasible through regular application of a repellent based on coconut oil. Owing to its strong association with poverty, sand flea disease would be an excellent starting point for a community-based fight against rural poverty.

Tungiasis: a poorly documented tropical dermatosis

Tungiasis is the parasitic skin disease caused by the sand flea Tunga penetrans, also called the jigger flea, found in most intertropical countries. The contamination occurs when walking barefoot in the sand: adult females actively burrow the foot epidermis leading to self-limited lesions responsible for itching or pain. The diagnosis is made on clinical observation and history of travelling to an endemic country. The simple treatment is surgical extraction of the flea.

Control of tungiasis through intermittent application of a plant-based repellent: an intervention study in a resource-poor community in Brazil

BACKGROUND

Tungiasis, an ectoparasitosis caused by the female sand flea Tunga penetrans, is an important health problem in many impoverished communities in the tropics. Sand flea disease is associated with a broad spectrum of clinical pathology and severe sequels are frequent. Treatment options are limited.

METHODOLOGY/PRINCIPAL FINDINGS

We assessed the effectiveness of the intermittent application of the plant-based repellent Zanzarin to reduce infestation intensity and tungiasis-associated morbidity in a resource-poor community in Brazil, characterized by a very high attack rate. The study population was randomized into three cohorts. Initially, during a period of four weeks, the repellent was applied twice daily to the feet of all cohort members. This reduced the number of embedded sandfleas to 0 in 98% of the participants. Thereafter members of cohort A applied the repellent every second week twice daily for one week, members of cohort B every fourth week for one week, and members of cohort C served as controls. Infestation intensity and tungiasis-associated morbidity were monitored during five months. The intermittent application of Zanzarin for one week every second week significantly reduced infestation intensity from a median 4 lesions (IQR 1-9) during the whole transmission season. In contrast, in cohort B (application of the repellent every fourth week) the infestation intensity remained twice as high (median 8 lesions, IQR 9-16; p = 0.0035), and in the control cohort C 3.5 times as high (median 14 lesions; IQR 7-26; p = 0.004 during the transmission season). Tungiasis-related acute pathology remained very low in cohort A (median severity score 2; IQR 1-4) as compared to cohort B (median severity score 5; IQR 3-7; p<0.001), and control cohort C (median severity score 6.5; IQR 4-8; p<0.001).

CONCLUSIONS/SIGNIFICANCE

Our study shows that in a setting with intense transmission, tungiasis-associated morbidity can be minimized through the intermittent application of a plant-based repellent.

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.

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.

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.

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.

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.