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Matharu AK, Ouma P, Njoroge MM, Amugune BL, Hyuga A, Mutebi F, Krücken J, Feldmeier H, Elson L, Fillinger U. Identification of tungiasis infection hotspots with a low-cost, high-throughput method for extracting Tunga penetrans (Siphonaptera) off-host stages from soil samples-An observational study. PLoS Negl Trop Dis 2024; 18:e0011601. [PMID: 38377105 PMCID: PMC10906885 DOI: 10.1371/journal.pntd.0011601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 03/01/2024] [Accepted: 02/02/2024] [Indexed: 02/22/2024] Open
Abstract
BACKGROUND The sand flea, Tunga penetrans, is the cause of a severely neglected parasitic skin disease (tungiasis) in the tropics and has received little attention from entomologists to understand its transmission ecology. Like all fleas, T. penetrans has environmental off-host stages presenting a constant source of reinfection. We adapted the Berlese-Tullgren funnel method using heat from light bulbs to extract off-host stages from soil samples to identify the major development sites within rural households in Kenya and Uganda. METHODS AND FINDINGS Simple, low-cost units of multiple funnels were designed to allow the extraction of >60 soil samples in parallel. We calibrated the method by investigating the impact of different bulb wattage and extraction time on resulting abundance and quality of off-host stages. A cross-sectional field survey was conducted in 49 tungiasis affected households. A total of 238 soil samples from indoor and outdoor living spaces were collected and extracted. Associations between environmental factors, household member infection status and the presence and abundance of off-host stages in the soil samples were explored using generalized models. The impact of heat (bulb wattage) and time (hours) on the efficiency of extraction was demonstrated and, through a stepwise approach, standard operating conditions defined that consistently resulted in the recovery of 75% (95% CI 63-85%) of all present off-host stages from any given soil sample. To extract off-host stages alive, potentially for consecutive laboratory bioassays, a low wattage (15-25 W) and short extraction time (4 h) will be required. The odds of finding off-host stages in indoor samples were 3.7-fold higher than in outdoor samples (95% CI 1.8-7.7). For every one larva outdoors, four (95% CI 1.3-12.7) larvae were found indoors. We collected 67% of all off-host specimen from indoor sleeping locations and the presence of off-host stages in these locations was strongly associated with an infected person sleeping in the room (OR 10.5 95% CI 3.6-28.4). CONCLUSION The indoor sleeping areas are the transmission hotspots for tungiasis in rural homes in Kenya and Uganda and can be targeted for disease control and prevention measures. The soil extraction methods can be used as a simple tool for monitoring direct impact of such interventions.
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Affiliation(s)
- Abneel K. Matharu
- Freie Universität Berlin, Institute for Parasitology and Tropical Veterinary Medicine, Berlin, Germany
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi, Kenya
| | - Paul Ouma
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi, Kenya
| | - Margaret M. Njoroge
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi, Kenya
| | - Billy L. Amugune
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi, Kenya
| | - Ayako Hyuga
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi, Kenya
| | - Francis Mutebi
- Makerere University, College of Veterinary Medicine, Animal Resources and Biosecurity, Kampala, Uganda
| | - Jürgen Krücken
- Freie Universität Berlin, Institute for Parasitology and Tropical Veterinary Medicine, Berlin, Germany
| | - Hermann Feldmeier
- Charité–Universitätsmedizin Berlin, Institute of Microbiology, Infectious Diseases and Immunology, Berlin, Germany
| | - Lynne Elson
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research (Coast), Kilifi, Kenya
- University of Oxford, Centre for Tropical Medicine and Global Health, Oxford, United Kingdom
| | - Ulrike Fillinger
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi, Kenya
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Hyuga A, Ouma P, Matharu AK, Krücken J, Kaneko S, Goto K, Fillinger U. Myth or truth: investigation of the jumping ability of Tunga penetrans (Siphonaptera: Tungidae). J Med Entomol 2024; 61:261-265. [PMID: 37861430 PMCID: PMC10784774 DOI: 10.1093/jme/tjad143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 09/26/2023] [Accepted: 10/09/2023] [Indexed: 10/21/2023]
Abstract
Female sand fleas (Tunga penetrans Linnaeus, 1758, Siphonaptera: Tungidae) cause a severe parasitic skin disease known as tungiasis. T. penetrans is a small flea, measuring less than 1 mm in length. The females of this species burrow into the skin of human and animal hosts and mostly affect the feet. This has led to the anecdotal assumption that T. penetrans, unlike its relatives in the Siphonaptera family, would have a limited jumping ability potentially not reaching higher body parts. However, there is no data supporting this. This study evaluated the jumping capabilities of T. penetrans for height and distance using sticky tapes. The vertical jump of the female T. penetrans ranged from 4.5 to 100 mm with a mean of 40 mm whereas the vertical jump of the male T. penetrans ranged from 1.2 to 138 mm with a mean of 46 mm. The horizontal jump of the female T. penetrans ranged from 18 to 138 mm with a mean of 64 mm and that of the male ranged from 9 to 251 mm with a mean of 80 mm. Based on the literature, fleas of various species have been described as jumping vertically 50-100 times their size and horizontally 5-100 times their size. In this respect, sand fleas appear to have equal expert jumping abilities to their relatives. Their aggregation on people's feet is not likely a result of their poor jumping ability but might be an adaptation to the host's behavior which would require further investigations.
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Affiliation(s)
- Ayako Hyuga
- Human Health Theme, International Centre of Insect Physiology and Ecology, Nairobi 00100, Kenya
| | - Paul Ouma
- Human Health Theme, International Centre of Insect Physiology and Ecology, Nairobi 00100, Kenya
| | - Abneel K Matharu
- Human Health Theme, International Centre of Insect Physiology and Ecology, Nairobi 00100, Kenya
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Robert-von-Ostertag-Str. 7, 14163 Berlin, Germany
| | - Jürgen Krücken
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Robert-von-Ostertag-Str. 7, 14163 Berlin, Germany
| | - Satoshi Kaneko
- Department of Eco-Epidemiology, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki-shi 852-8523, Nagasaki, Japan
| | - Kensuke Goto
- Division of Health and Safety Sciences Education, Department of Educational Collaboration, Osaka Kyoiku University, 4-698-1 Asahigaoka, Kashiwara-shi 582-8582, Osaka, Japan
| | - Ulrike Fillinger
- Human Health Theme, International Centre of Insect Physiology and Ecology, Nairobi 00100, Kenya
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Otieno B, Elson L, Matharu AK, Riithi N, Chongwo E, Katana K, Nasambu C, Mutebi F, Feldmeier H, Krücken J, Fillinger U, Abubakar A. Neurocognitive and mental health outcomes in children with tungiasis: a cross-sectional study in rural Kenya and Uganda. Infect Dis Poverty 2023; 12:100. [PMID: 37964353 PMCID: PMC10644620 DOI: 10.1186/s40249-023-01154-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 11/06/2023] [Indexed: 11/16/2023] Open
Abstract
BACKGROUND Tungiasis, a neglected tropical parasitosis, disproportionately affects children. Few empirical studies have reported neurocognitive and mental health outcomes of children with ectoparasitic skin diseases like tungiasis. Pathophysiology of tungiasis suggests it could detrimentally affect cognition and behaviour. This study pioneered the investigation of neurocognitive and mental health outcomes in children with tungiasis. METHODS This was a multi-site cross-sectional study including 454 quasi-randomly sampled school-children aged 8-14 from 48 randomly selected schools in two counties in Kenya and a district in Uganda. The participants were stratified into infected and uninfected based on the presence of tungiasis. The infected were further classified into mild and severe infection groups based on the intensity of the infection. Adapted, validated, and standardized measures of cognition and mental health such as Raven Matrices and Child Behaviour Checklist were used to collect data. Statistical tests including a multilevel, generalized mixed-effects linear models with family link set to identity were used to compare the scores of uninfected and infected children and to identify other potential risk factors for neurocognitive and behavioural outcomes. RESULTS When adjusted for covariates, mild infection was associated with lower scores in literacy [adjusted β(aβ) = - 8.9; 95% confidence interval (CI) - 17.2, - 0.6], language (aβ = - 1.7; 95% CI - 3.2, - 0.3), cognitive flexibility (aβ = - 6.1; 95% CI - 10.4, - 1.7) and working memory (aβ = - 0.3; 95% CI - 0.6, - 0.1). Severe infection was associated with lower scores in literacy (aβ = - 11.0; 95% CI - 19.3, - 2.8), response inhibition, (aβ = - 2.2; 95% CI - 4.2, - 0.2), fine motor control (aβ = - 0.7; 95% CI - 1.1, - 0.4) and numeracy (aβ = - 3; 95% CI - 5.5, - 0.4). CONCLUSIONS This study provides first evidence that tungiasis is associated with poor neurocognitive functioning in children. Since tungiasis is a chronic disease with frequent reinfections, such negative effects may potentially impair their development and life achievements.
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Affiliation(s)
- Berrick Otieno
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Hospital Road, Kilifi, Kenya.
| | - Lynne Elson
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Hospital Road, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Abneel K Matharu
- International Centre of Insect Physiology and Ecology (ICIE), Human Health Theme, Nairobi, Kenya
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Naomi Riithi
- International Centre of Insect Physiology and Ecology (ICIE), Human Health Theme, Nairobi, Kenya
| | - Esther Chongwo
- Institute for Human Development, Aga Khan University, Nairobi, Kenya
| | - Khamis Katana
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Hospital Road, Kilifi, Kenya
| | - Carophine Nasambu
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Hospital Road, Kilifi, Kenya
| | - Francis Mutebi
- School of Veterinary Medicine and Animal Resources, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala , Uganda
| | | | - Jürgen Krücken
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Ulrike Fillinger
- International Centre of Insect Physiology and Ecology (ICIE), Human Health Theme, Nairobi, Kenya
| | - Amina Abubakar
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Hospital Road, Kilifi, Kenya
- Institute for Human Development, Aga Khan University, Nairobi, Kenya
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Elson L, Matharu AK, Riithi N, Ouma P, Mutebi F, Feldmeier H, Krücken J, Fillinger U. Characterization of tungiasis infection and morbidity using thermography in Kenya revealed higher disease burden during COVID-19 school closures. Infect Dis Poverty 2023; 12:24. [PMID: 36941724 PMCID: PMC10027580 DOI: 10.1186/s40249-023-01080-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 03/09/2023] [Indexed: 03/23/2023] Open
Abstract
BACKGROUND Tungiasis is a neglected tropical skin disease caused by the sand flea Tunga penetrans. Female fleas penetrate the skin, particularly at the feet, and cause severe inflammation. This study aimed to characterize disease burden in two highly affected regions in Kenya, to test the use of thermography to detect tungiasis-associated inflammation and to create a new two-level classification of disease severity suitable for mapping, targeting, and monitoring interventions. METHODS From February 2020 to April 2021, 3532 pupils age 8-14 years were quasi-randomly selected in 35 public primary schools and examined for tungiasis and associated symptoms. Of the infected pupils, 266 were quasi-randomly selected and their households visited, where an additional 1138 family members were examined. Inflammation was assessed using infra-red thermography. A Clinical score was created combining the number of locations on the feet with acute and chronic symptoms and infra-red hotspots. RESULTS The overall prevalence of tungiasis among all the school pupils who were randomly selected during survey rounds 1 and 3 was 9.3% [95% confidence interval (CI): 8.4-10.3]. Based on mixed effects logistic models, the odds of infection with tungiasis among school pupils was three times higher in Kwale (coastal Kenya) than in Siaya [western Kenya; adjusted odds ratio (aOR) = 0.36, 95% CI: 0.18-0.74]; three times higher in males than in females (aOR = 3.0, 95% CI: 2.32-3.91) and three times lower among pupils sleeping in a house with a concrete floor (aOR = 0.32, 95% CI: 0.24-0.44). The odds of finding an infected person among the household population during surveys before the COVID-19 pandemic was a third (aOR = 0.32, 95% CI: 0.19-0.53) of that when schools were closed due to COVID-19 restrictions and approximately half (aOR = 0.44, 95% CI: 0.29-0.68) in surveys done after school re-opening (round 3). Infection intensity was positively correlated with inflammation as measured by thermography (Spearman's rho = 0.68, P < 0.001) and with the clinical score (rho = 0.86, P < 0.001). Based on the two-level classification, severe cases were associated with a threefold higher level of pain (OR = 2.99, 95% CI: 2.02-4.43) and itching (OR = 3.31, 95% CI: 2.24-4.89) than mild cases. CONCLUSIONS Thermography was a valuable addition for assessing morbidity and the proposed two-level classification of disease severity clearly separated patients with mild and severe impacts. The burden of tungiasis was considerably higher in households surveyed during COVID-19 restrictions suggesting underlying risks are found in the home environment more than in school.
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Affiliation(s)
- Lynne Elson
- KEMRI-Wellcome Trust Research Programme, Hospital Road, Kilifi, Kenya.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
| | - Abneel K Matharu
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi, Kenya
| | - Naomi Riithi
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi, Kenya
| | - Paul Ouma
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi, Kenya
| | - Francis Mutebi
- College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala, Uganda
| | - Hermann Feldmeier
- Institute of Microbiology, Infectious Diseases and Immunology, Charité University Medicine, Berlin, Germany
| | - Jürgen Krücken
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Ulrike Fillinger
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi, Kenya
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Amugune BL, Matharu AK, Ouma P, Mutebi F, Elson L, Fillinger U, Krücken J. Cost-Effective PCR-Based Identification of Tunga penetrans (Siphonaptera) Larvae Extracted from Soil Samples Containing PCR Inhibitor-Rich Material. Insects 2022; 14:5. [PMID: 36661934 PMCID: PMC9865934 DOI: 10.3390/insects14010005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/15/2022] [Accepted: 12/17/2022] [Indexed: 06/17/2023]
Abstract
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, Cq 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.
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Affiliation(s)
- Billy L. Amugune
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi 00100, Kenya
| | - Abneel K. Matharu
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi 00100, Kenya
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, 14163 Berlin, Germany
| | - Paul Ouma
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi 00100, Kenya
| | - Francis Mutebi
- School of Veterinary Medicine and Animal Resources, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala 10218, Uganda
| | - Lynne Elson
- KEMRI-Wellcome Trust Research Programme, Kilifi 80108, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - Ulrike Fillinger
- International Centre of Insect Physiology and Ecology, Human Health Theme, Nairobi 00100, Kenya
| | - Jürgen Krücken
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, 14163 Berlin, Germany
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