Tungiasis - A Janus-faced parasitic skin disease

Present and future: infectious tropical travel rashes and the impact of climate change

In this article, we discuss pertinent cutaneous findings with which patients may present after travel to tropical destinations. We address arthropod-borne infectious diseases such as cutaneous leishmaniasis, Chagas disease, cutaneous larva migrans, and myiasis. We discuss other relevant diseases with cutaneous signs such as monkey pox and severe acute respiratory syndrome coronavirus 2. We provide clinicians with information regarding the background, diagnosis, treatment, and prevention of these tropical rashes. In addition, we address the impact that climate change will have on the temporal and geographic incidence of these rashes. Viral, fungal, and vector-borne diseases have seen a geographic expansion into more northern latitudes. Among these are tick-borne Lyme disease, aquatic snail-related seabather's eruption, and atopic dermatitis. As these diseases spread, we believe that the updated information within this article is significant to the practicing physician in today's warming world.

Cost-Effective PCR-Based Identification of Tunga penetrans (Siphonaptera) Larvae Extracted from Soil Samples Containing PCR Inhibitor-Rich Material

Tungiasis is a neglected tropical disease caused by skin-penetrating female Tunga penetrans fleas. Although tungiasis causes severe health problems, its ecology is poorly understood and morphological descriptions of the larvae are unavailable. To identify T. penetrans immature stages and sites where they develop, diagnostic PCRs are required. However, flea larvae feed on soil organic matter rich in PCR inhibitors. Here, three DNA preparation methods, including a soil DNA kit that removes inhibitors, a simple ammonium acetate precipitation approach (AmAcet) and a crude lysate of larvae (CL), were combined with amplification by the highly processive FIREPol^® Taq or the inhibitor-resistant Phusion^® polymerase. Independent of the polymerase used, the frequency of successful amplification, C_q values and PCR efficacies for the low-cost CL and AmAcet methods were superior to the commercial kit for amplification of a 278 bp partial internal transcribed spacer-2 (ITS-2) and a 730 bp pan-Siphonaptera cytochrome oxidase II PCR. For the CL method combined with Phusion^® polymerase, the costs were approximately 20-fold lower than for the methods based on the soil DNA kit, which is a considerable advantage in resource-poor settings. The ITS-2 PCR did not amplify Ctenocephalides felis genomic or Tunga trimammilata ITS-2 plasmid DNA, meaning it can be used to specifically identify T. penetrans.

Clinical and epidemiological survey of tungiasis in Madagascar

BACKGROUND

Tungiasis is a dermal parasitic infection, classified as a neglected tropical disease. Madagascar is one of endemic countries which have been committed for decades to control the tungiasis as a public health issue. Despite this medical importance, little is known about the prevalence and epidemiology of the disease in this country.

METHODS

A descriptive cross-sectional survey was performed in two endemic foci of Antananarivo and Toamasina.

RESULTS

In total, 2971 suspected individuals were surveyed. Of them, 643 individuals were excluded due to absence or refusing clinical examinations. Therefore, 2328 individuals with aforementioned criteria were clinically examined, 320 cases (13.7%) were found infected by Tunga penetrans. Of these 320 infected cases, 241 individuals came from rural regions against 79 from urban areas. The sex ratio of infected cases was 1.15 with an age average of 34.7 years old. Most of them were illiterate (185/320, 57.8%) with no habit of feet washing (210/320, 65.6%). The majority (198/320, 61.9%) inhabited in the houses constructed by falafa providing a suitable breeding location for Tunga ectoparasites. Based on clinical examination, most of the patients (298/320, 93.1%) had the lesions on their toes followed by those possessed the lesions on the plantar (140/320, 43.7%). The lesion stages of IV and V were observed in 49.1% (157/320) of visited patients which were more common in rural regions (86%) than in urban areas (14%). For treatment, removing the fleas using needle (122/320, 38.1%), followed by the application of petroleum (100/320, 31.2%) were among the most traditional remedies used by our patients.

CONCLUSION

This investigation highlights a high burden of tungiasis in studied endemic foci in particular in rural regions. These results can be helpful in control management strategies against this parasitosis in Madagascar.

Evaluating the potentials of randomised integrated control trial on tungiasis in a South-western Nigerian community

Considering the fact that new, safe and incorporable treatment alternatives to therapeutic prophylaxis for tungiasis are lacking and sometimes proving difficult, this present study evaluated the potentials of integrating control approach involving focal premise treatment using 5% emulsifiable concentrate of cypermethrin, and topical application of Piper guineense oil with personal protection. Of the 90 houses selected, their floors were classified into paved rooms & unpaved verandas, paved verandas & unpaved rooms, paved rooms & verandas, and unpaved rooms & verandas, and tested for the presence of sand fleas using the sweeping and beating as well as soil collection and extraction by tullgren funnel method before fumigation. A total of 100 individuals partitioned into four groups of 25 individuals each were assigned 3%, 5%, 10% and 15% of P. guineense oil irrespective of stages of embedded fleas. The mean of sand fleas decreased from 1.14, 0.07, 0.21, and 1.66 to 0.37, 0.02, 0.09 and 1.08 after two weeks of single spray compared to the untreated location (p <  0.001). Furthermore, the mean lesions of stage I reduced to 0 after 2 to 6 days of 3%, 5%, 10% and 15% ointment application, and stage II and III after 10 to 12 days of 10% and 15% application respectively. The difference between tungiasis stages and exposure time for P. guineense ointment was highly significant p = 0.007 and p = 0.0002. Notable reduction in severity score of acute and chronic tungiasis was observed thus indicating effectiveness of the topical ointment. Hexanolic oil extracts of P. guineense in 10% and 15% concentration would kill embedded sand flea and ameliorate the sufferings in endemic settings.

Therapeutic Potential of Tea Tree Oil for Tungiasis

Tungiasis (sand flea disease) is a neglected tropical disease caused by penetration of female sand fleas, Tunga penetrans, into a person's skin usually in their feet. The disease inflicts immense pain and suffering on millions of people, particularly children. The condition is most prevalent in Latin America, the Caribbean, and sub-Saharan Africa. Currently, there is no standard drug treatment for tungiasis. The available treatment options are fairly limited and unrealistic to use in endemic areas; as a result, in desperation, the affected people do more harm to themselves by extracting the fleas with non-sterile instruments, further exposing themselves to secondary bacterial infections and/or transmission of diseases such as hepatitis B virus, hepatitis C virus, or HIV. This highlights the urgent need for simpler, safer, and effective treatment options for tungiasis. Tea tree oil (TTO) has long been used as an antiseptic with extensive safety and efficacy data. The evidence on parasiticidal properties of TTO against ectoparasites such as head lice, mites, and fleas is also compelling. The purpose of this review is to discuss the current tungiasis treatment challenges in endemic settings and highlight the potential role of TTO in the treatment of tungiasis.

Presence of dogs and proximity to a wildlife reserve increase household level risk of tungiasis in Kwale, Kenya

Introduction

Tungiasis is a ectopic skin disease caused by some species of fleas in the Tunga genus, most notably T. penetrans. The disease afflicts poor and marginalized communities in developing countries. Transmission of tungiasis comprises a complex web of factors including domesticated animals and wildlife. This research explores animal and environmental risk factors for tungiasis in an area adjacent to a wildlife reserve in Kwale, Kenya.

Methods

A two-stage complex sampling strategy was used. Households were selected from three areas in and around Kwale Town, Kenya, an area close to the Kenyan Coast. Households were listed as positive if at least one member had tungiasis. Each household was administered a questionnaire regarding tungiasis behaviors, domesticated animal assets, and wild animal species that frequent the peridomiciliary area. Associations of household tungiasis were tests with household and environmental variables using regression methods.

Results

The study included 319 households. Of these, 41 (12.85%) were found to have at least one person who had signs of tungiasis. There were 295 (92.48%) households that possessed at least one species of domesticated animal. It was reported that wildlife regularly come into the vicinity of the home 90.59% of households. Presence of dogs around the home (OR 3.85; 95% CI 1.84; 8.11) and proximity to the park were associated with increased risk for tungiasis infestation in humans in a multivariate regression model.

Conclusions

Human tungiasis is a complex disease associated with domesticated and wild animals. Canines in particular appear to be important determinants of household level risk.

Intensity and clinical morbidities of tungiasis in an impoverished south-west Nigerian community

Sand fleas infestation, Tunga penetrans, remains a neglected tropical disease of public-health concern in many countries. Tungiasis can lead to destruction of the feet causing serious discomfort and deformities. This study aim was to determine the intensity rate and clinical morbidities of tungiasis among the people living in Igbokoda, Ondo State, Nigeria. A community-based cross-sectional survey was conducted among households in three villages in Igbokoda. Hands and feet of selected household members were examined, while fleas on different floor types of houses were sampled by soil collection and extraction by tullgren funnel method. Sand fleas were equally sampled from legs of infested individuals by hand picking. Intensity was determined in terms of number of lesions and fleas in different floor-types. Tungiasis-associated morbidities was assessed using acute and chronic lesions severity scores. The study revealed that moderate infestation was observed in 173 infested individuals and severe infestation in 16 infested individuals. A total of 5293 lesions was observed out of which 3098 were viable. The flea burdens on sampled floors and legs were 127 and 146 fleas respectively occurring mostly in unpaved veranda and rooms (65 and 62 fleas respectively). Tungiasis lesions observed in males were more intense compared to females. Flea lesions and burdens with respect to age stratification and location were significant P < 0.0001. Difficulty in walking, pain upon pressure and deformation of the feet were the most common tungiasis-associated morbidity recorded. Also, tungiasis-associated morbidities, and flea number sampled on legs and on floor of environment were reportedly intense. Therefore, scaling up an appropriate and affordable intervention approach targeted at the fleas would serve as a relief to the scourge of tungiasis in Igbokoda community.

Parasite-bacteria interrelationship

Parasites and bacteria have co-evolved with humankind, and they interact all the time in a myriad of ways. For example, some bacterial infections result from parasite-dwelling bacteria as in the case of Salmonella infection during schistosomiasis. Other bacteria synergize with parasites in the evolution of human disease as in the case of the interplay between Wolbachia endosymbiont bacteria and filarial nematodes as well as the interaction between Gram-negative bacteria and Schistosoma haematobium in the pathogenesis of urinary bladder cancer. Moreover, secondary bacterial infections may complicate several parasitic diseases such as visceral leishmaniasis and malaria, due to immunosuppression of the host during parasitic infections. Also, bacteria may colonize the parasitic lesions; for example, hydatid cysts and skin lesions of ectoparasites. Remarkably, some parasitic helminths and arthropods exhibit antibacterial activity usually by the release of specific antimicrobial products. Lastly, some parasite-bacteria interactions are induced as when using probiotic bacteria to modulate the outcome of a variety of parasitic infections. In sum, parasite-bacteria interactions involve intricate processes that never cease to intrigue the researchers. However, understanding and exploiting these interactions could have prophylactic and curative potential for infections by both types of pathogens.

A chromosome-level assembly of the cat flea genome uncovers rampant gene duplication and genome size plasticity

BACKGROUND

Fleas (Insecta: Siphonaptera) are small flightless parasites of birds and mammals; their blood-feeding can transmit many serious pathogens (i.e., the etiological agents of bubonic plague, endemic and murine typhus). The lack of flea genome assemblies has hindered research, especially comparisons to other disease vectors. Accordingly, we sequenced the genome of the cat flea, Ctenocephalides felis, an insect with substantial human health and veterinary importance across the globe.

RESULTS

By combining Illumina and PacBio sequencing of DNA derived from multiple inbred female fleas with Hi-C scaffolding techniques, we generated a chromosome-level genome assembly for C. felis. Unexpectedly, our assembly revealed extensive gene duplication across the entire genome, exemplified by ~ 38% of protein-coding genes with two or more copies and over 4000 tRNA genes. A broad range of genome size determinations (433-551 Mb) for individual fleas sampled across different populations supports the widespread presence of fluctuating copy number variation (CNV) in C. felis. Similarly, broad genome sizes were also calculated for individuals of Xenopsylla cheopis (Oriental rat flea), indicating that this remarkable "genome-in-flux" phenomenon could be a siphonapteran-wide trait. Finally, from the C. felis sequence reads, we also generated closed genomes for two novel strains of Wolbachia, one parasitic and one symbiotic, found to co-infect individual fleas.

CONCLUSION

Rampant CNV in C. felis has dire implications for gene-targeting pest control measures and stands to complicate standard normalization procedures utilized in comparative transcriptomics analysis. Coupled with co-infection by novel Wolbachia endosymbionts-potential tools for blocking pathogen transmission-these oddities highlight a unique and underappreciated disease vector.

Factors associated with tungiasis among primary school children: a cross-sectional study in a rural district in Rwanda

BACKGROUND

Tungiasis is a relatively frequent ectoparasitosis in low-income settings, yet its morbidity and social impact are still not well understood due to the scarcity of information. In Rwanda, data on the magnitude and conditions leading to the tungiasis is rare. This study sought to determine the prevalence and factors associated with tungiasis among primary school children in Rwandan setting.

METHOD

A descriptive cross-sectional study utilising systematic random sampling method was adopted to select 384 children from three primary schools. From July to October 2018, data were collected on socio-demographic characteristics of children, parents, and households. Logistic regression was applied to analyse socio-demographic factors associated with tungiasis with a level of significance set at P-value< 0.05.

RESULTS

Prevalence of tungiasis among three primary schools was 23%. Factors associated with tungiasis included walking barefoot (AOR: 78.41; 95% CI: 17.91-343.10), irregular wearing of shoes (AOR: 24.73; 95% CI: 6.27-97.41), having dirty feet (AOR: 12.69; 95% CI: 4.93-32.64), wearing dirty clothes (AOR: 12.69; 95% CI: 4.18-38.50), and living in a house with earthen plastered floor (AOR: 28.79; 95% CI: 7.11-116.57). Children infected with tungiasis attended class less frequently (AOR: 19.16, 95%CI: 7.20-50.97) and scored lower (AOR: 110.85, 95%CI: 43.08-285.20) than those non-infected. The low school attendance and poor performance could be partly explained by difficulty of walking, lack of concentration during school activities, and isolation or discrimination from classmates.

CONCLUSION

Tungiasis was a public health challenge among school going children in a rural Rwandan setting. This study revealed that children affected with tungiasis had poor hygiene, inadequate housing environments and consequently poor school attendance and performance. Improving socio-economic conditions of households with special emphasis on hygiene of family members and housing conditions, would contribute to preventing tungiasis.

Tungiasis: a poorly-known diagnosis in Europe. Two paradigmatic cases from Portugal

Tungiasis is a cutaneous parasitosis caused by infestation of the skin by gravid fleas of the genus Tunga, mainly Tunga penetrans. This flea is very common in tropical and subtropical regions of the globe, but not in Europe. The infestation is acquired by walking barefoot or lying in places where the flea is present, usually beaches or sandy soils. We report two unrelated cases of imported tungiasis in Portugal that presented to our clinic in the same week. We draw attention to one of the most common dermatological diseases in travelers returning from tropical countries, the diagnosis of which is primarily clinical but nonetheless is largely unfamiliar to clinicians attending those patients.

Treatment of tungiasis with a two-component dimeticone: a comparison between moistening the whole foot and directly targeting the embedded sand fleas

BACKGROUND

Tungiasis (sand flea disease) is caused by the penetration of female sand fleas (Tunga penetrans, Siphonaptera) into the skin. It belongs to the neglected tropical diseases and is prevalent in South America, the Caribbean and sub-Saharan Africa. Tungiasis predominantly affects marginalized populations and resource-poor communities in both urban and rural areas. In the endemic areas, patients do not have access to an effective and safe treatment. A proof-of-principle study in rural Kenya has shown that the application of a two-component dimeticone (NYDA®) which is a mixture of two low viscosity silicone oils caused almost 80% of the embedded sand fleas to lose their viability within 7 days.

METHODS

In this study we compared the efficacy of two distinct modes of application of NYDA®; one targeted application to the area where the parasite protrudes through the skin and one comprehensive application to the whole foot.

RESULTS

Independent of the two modes of application, the dimeticone caused more than 95% of embedded sand fleas to lose all signs of viability within 7 days. The targeted application killed embedded sand fleas more rapidly compared to when the whole foot was covered. The proportion of viable lesions at day two were 7.0 versus 23.4% (p < 0.01) and at day five 3.9 versus 12.5% (p < 0.02).

CONCLUSIONS

Our findings suggest that the dimeticone could provide a safe and effective treatment for tungiasis in areas with difficult access to health care.

TRIAL REGISTRATION

ISRCTN ISRCTN74306878.

Got the Travel Bug? A Review of Common Infections, Infestations, Bites, and Stings Among Returning Travelers

The popularity of international travel continues to increase among Americans, even though they often experience subsequent illness on return from their journey. The pathogens responsible are not necessarily endemic to the destination itself but are often the result of poor sanitary conditions or activities engaged in while away. Skin disease ranks third among all medical concerns in returning travelers. This review addresses the pathogenesis, epidemiology, clinical presentation, and treatment of the most common skin diseases in returning travelers: insect bites and bedbugs, cutaneous larva migrans, scabies, tungiasis, myiasis, leishmaniasis, viral exanthems, and marine envenomation. Primary care physicians and dermatologists should be familiar with these illnesses and a general approach to their evaluation and management.

Treatment of Tungiasis with dimeticone: a proof-of-principle study in rural Kenya

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

Tungiasis (sand flea disease), a parasitic skin disease, causes important morbidity, and eventually leads to mutilation of the feet. 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. We identified the three last abdominal segments of Tunga penetrans which protrude through the skin and through which the parasite breathes, defecates, and expels eggs - as an Achilles heel of embedded sand fleas. In a proof-of-principle study we investigated whether this Achilles heel is vulnerable to dimeticone with a low viscosity and a high creeping property. We randomized the left and the right feet to either receive a topical application of KMnO4 (the standard treatment in Kenya) or of dimeticone. The major outcome measure was the absence of viability signs of the treated sand fleas. The study shows that the topical application of a mixture of two dimeticones (NYDA) effectively kills embedded sand fleas within seven days. Since dimeticones are considered to be wholly non-toxic and are not expensive the new treatment could become a means to control tungiasis-associated morbidity on the population level.

The 2014 FIFA World Cup: communicable disease risks and advice for visitors to Brazil--a review from the Latin American Society for Travel Medicine (SLAMVI)

The next FIFA World Cup will be held in Brazil in June-July 2014. Around 600,000 international visitors and participants (as well over 3 million domestic travelers) are expected. This event will take place in twelve cities. This event poses specific challenges, given its size and the diversity of attendees, including the potential for the transmission of imported or endemic communicable diseases, especially those that have an increased transmission rate as a result of close human proximity, eg, seasonal influenza, measles but also tropical endemic diseases. In anticipation of increased travel, a panel of experts from the Latin American Society for Travel Medicine (SLAMVI) developed the current recommendations regarding the epidemiology and risks of the main communicable diseases in the major potential destinations, recommended immunizations and other preventives measures to be used as a basis for advice for travelers and travel medicine practitioners. Mosquito-borne infections also pose a challenge. Dengue poses a significant risk in all states, including the host cities. Vaccination against yellow fever is recommended except for travelers who will only visit coastal areas. Travelers visiting high-risk areas for malaria (Amazon) should be assessed regarding the need for chemoprophylaxis. Chikunguya fever may be a threat for Brazil, given the presence of Aedes aegypti, vector of dengue, and the possibility of travelers bringing the virus with them when attending the event. Advice on the correct timing and use of repellents and other personal protection measures is key to preventing these vector-borne infections. Other important recommendations for travelers should focus on preventing water and food-borne diseases such as hepatitis A, typhoid fever, giardiasis and traveler's diarrhea. Sexually transmitted diseases (STD) should be also mentioned and the use of condoms advocated. This review addresses pre-travel, preventive strategies to reduce the risk of acquiring communicable diseases during a mass gathering such as the World Cup and also reviews the spectrum of endemic infections in Brazil to facilitate the recognition and management of infectious diseases in travelers returning to their countries of origin.