Pharmacotherapy of ectoparasitic infections

Clinical practice guidelines for the diagnosis and treatment of scabies

Scabies, caused by the Sarcoptes scabiei var hominis mite burrowing into the skin, is a highly contagious disease characterized by intense nocturnal itching. Its global impact is considerable, affecting more than 200 million individuals annually and posing significant challenges to healthcare systems worldwide. Transmission occurs primarily through direct skin-to-skin contact, contributing to its widespread prevalence and emergence as a substantial public health concern affecting large populations. This review presents consensus-based clinical practice guidelines for diagnosing and managing scabies, developed through the fuzzy Delphi method by dermatology, parasitology, pediatrics, pharmacology, and public health experts. The presence of burrows containing adult female mites, their eggs, and excreta is the diagnostic hallmark of scabies. Definitive diagnosis typically involves direct microscopic examination of skin scrapings obtained from these burrows, although dermoscopy has become a diagnostic tool in clinical practice. Treatment modalities encompass topical agents, such as permethrin, balsam of Peru, precipitated sulfur, and benzyl benzoate. In cases where topical therapy proves inadequate or in instances of crusted scabies, oral ivermectin is recommended as a systemic treatment option. This comprehensive approach addresses the diagnostic and therapeutic challenges associated with scabies, optimizing patient care, and management outcomes.

Diabetes mellitus and serum organochlorine pesticides mixtures in Mexican women

BACKGROUND

Very recently, it has been reported that exposure to different mixtures of organochlorine pesticides (OCP) is associated with the development of diabetes mellitus (DM). In Mexico, DM is a public health problem that might be related to the historical intense use of OCP. We aimed to evaluate, the association between DM and serum concentrations of OCP mixtures, and identify the main contributors within them.

METHODS

We conducted a secondary cross-sectional analysis on the control group from a breast cancer population-based case-control study conducted from 2007 to 2011 in Northern Mexico. We identified 214 self-reported diabetic women and 694 non-diabetics. We obtained direct information about sociodemographic, lifestyle and reproductive characteristics. We determined 24 OCP and metabolites in serum by gas chromatography using an electron capture micro detector. We used Weighted Quantile Sum regression to assess the association of DM and exposure to multiple OCP, and the contribution of each compound within the mixture.

RESULTS

We found a positive adjusted association between DM and an OCP mixture (OR: 2.63, 95%CI: 1.85, 3.74), whose primary contribution arose from p, p'-DDE (mean weight 23.3%), HCB (mean weight 17.3%), trans nonachlor (mean weight 15.4%), o, p'-DDE (mean weight 7.3%), heptachlor epoxide (mean weight 5.9%), oxychlordane (mean weight 4.7%), and heptachlor (mean weight 4.5%). In addition, these OCP along with p, p'-DDT and cis chlordane, were of concern and remained associated when excluding hypertensive women from the analysis (OR 2.55; 95% CI 1.56, 4.18).

CONCLUSIONS

Our results indicate, for the first time in a Latin-American population, that the concomitant exposure to multiple OCP is associated with DM. Further research is needed since the composition of OCP mixtures may vary according to regional pesticides use patterns.

Mange in Rabbits: An Ectoparasitic Disease with a Zoonotic Potential

Mange in rabbits is a very important parasitic disease causing high losses. The disease is caused mainly by Sarcoptes scabiei, Psoroptes cuniculi, Cheyletiella parasitovorax, and Notoedres cati. Body mange and ear mange are the most common forms of this disease in rabbits. Animals can get mite infestation through direct contact with infected animals or contaminated fomites. This infestation is characterized by zoonotic nature and public health burden. The skin affection is characterized by pruritus, alopecia, severe cachexia, and sometimes death. Infestation is diagnosed mainly by skin scraping and microscopic examination. Control measures mainly depend on the use of different types of systemic and topical acaricides and the use of natural products and supportive elements. Vaccine is not commercially available and is still under investigation. Accordingly, this review article was designed to shed the light on the mange disease in rabbits in terms of mite's infestation and susceptibility, clinical manifestations, zoonosis, diagnosis, and control strategies.

Molecular drug targets for scabies: a medicinal chemistry perspective

Sarcoptes scabiei is a causative organism for scabies that affects an estimated global population of 300 million and remains a disease of significant concern. Recently, a number of potential drug targets were identified for scabies, including hydrolytic enzymes, inactivated paralogues of hydrolytic enzymes, inhibitors of host proteolytic enzymes and other proteins of interest. These discoveries remain confined to academic laboratories and institutions, failing to attract interest from researchers in commercial drug development. Here, we summarize the latest developments in the scabies mite biology and the drug targets that were subsequently identified, and we propose several peptide and nonpeptide ligands targeting the hot spots for protein-protein interactions. We also identify gaps in the development of ligands as inhibitors or modulators of these macromolecules.

Antimalarial Drugs for Malaria Elimination

The diversity of Anopheles species and the environmental issues posed by the large-scale use of insecticides make it unlikely that malaria elimination will be achieved by fighting mosquitoes only. Malaria elimination necessitates targeting the parasite itself. For this, in the absence of efficient vaccines against the disease, antimalarial drugs remain the primary tool. We present here the limitations of currently available antimalarials and the different implementation strategies of these drugs, which ultimately depends on the epidemiological context of the disease.

Therapeutic Potential of Tea Tree Oil for Scabies

Globally, scabies affects more than 130 million people at any time. In the developed world, outbreaks in health institutions and vulnerable communities result in a significant economic burden. A review of the literature demonstrates the emergence of resistance toward classical scabicidal treatments and the lack of effectiveness of currently available scabicides in reducing the inflammatory skin reactions and pyodermal progression that occurs in predisposed patient cohorts. Tea tree oil (TTO) has demonstrated promising acaricidal effects against scabies mites in vitro and has also been successfully used as an adjuvant topical medication for the treatment of crusted scabies, including cases that did not respond to standard treatments. Emerging acaricide resistance threatens the future usefulness of currently used gold standard treatments (oral ivermectin and topical permethrin) for scabies. The imminent development of new chemical entities is doubtful. The cumulative acaricidal, antibacterial, antipruritic, anti-inflammatory, and wound healing effects of TTO may have the potential to successfully reduce the burden of scabies infection and the associated bacterial complications. This review summarizes current knowledge on the use of TTO for the treatment of scabies. On the strength of existing data for TTO, larger scale, randomized controlled clinical trials are warranted.

Scabies: an ancient global disease with a need for new therapies

BACKGROUND

Scabies is an ancient disease (documented as far back as 2500 years ago). It affects about 300 million people annually worldwide, and the prevalence is as high as about 60% in Indigenous and Torres Strait Islander children in Australia. This is more than six times the rate seen in the rest of the developed world. Scabies is frequently complicated by bacterial infection leading to the development of skin sores and other more serious consequences such as septicaemia and chronic heart and kidney diseases. This causes a substantial social and economic burden especially in resource poor communities around the world.

DISCUSSION

Very few treatment options are currently available for the management of scabies infection. In this manuscript we briefly discuss the clinical consequences of scabies and the problems found (studies conducted in Australia) with the currently used topical and oral treatments. Current scabies treatment options are fairly ineffective in preventing treatment relapse, inflammatory skin reactions and associated bacterial skin infections. None have ovicidal, antibacterial, anti-inflammatory and/or anti-pruritic properties. Treatments which are currently available for scabies can be problematic with adverse effects and perhaps of greater concern the risk of treatment failure. The development of new chemical entities is doubtful in the near future. Though there may be potential for immunological control, the development of a vaccine or other immunotherapy modalities may be decades away. The emergence of resistance among scabies mites to classical scabicides and ineffectiveness of current treatments (in reducing inflammatory skin reactions and secondary bacterial infections associated with scabies), raise serious concerns regarding current therapy. Treatment adherence difficulties, and safety and efficacy uncertainties in the young and elderly, all signal the need to identify new treatments for scabies.

[P2X4 or P2X7: which of these two receptors is the best target to promote salivation?]

P2X purinergic receptors are receptors which, after ATP binding, form a channel permeant to monovalent and divalent cations. Acinar and ductal cells from salivary glands express P2X4 and P2X7 receptors. The P2X4 receptor has a high affinity for ATP, rapidly desensitizes and is mostly located on the basal membrane of acinar cells. The P2X7 receptor has a very low affinity for ATP. After a sustained activation, the permeability of the channel formed by this receptor increases eventually leading to the death of the cell. This receptor is located mostly on the apical membrane of acinar and ductal cells. It is suggested that the sequential activation of the two receptors contributes to the secretory response to ATP. A low concentration of ATP released by nerve endings transiently activates the P2X4 receptors and promotes the release of secretory granules containing ATP. The local increase of the concentration of the nucleotide at the vicinity of P2X7 receptors accounts for their activation. This further increases the exocytosis.

Bed bugs: clinical relevance and control options

Since the late 1990s, bed bugs of the species Cimex lectularius and Cimex hemipterus have undergone a worldwide resurgence. These bed bugs are blood-sucking insects that readily bite humans. Cutaneous reactions may occur and can start out as small macular lesions that can develop into distinctive wheals of around 5 cm in diameter, which are accompanied by intense itching. Occasionally, bullous eruptions may result. If bed bugs are numerous, the patient can present with widespread urticaria or eythematous rashes. Often, bites occur in lines along the limbs. Over 40 pathogens have been detected in bed bugs, but there is no definitive evidence that they transmit any disease-causing organisms to humans. Anemia may result when bed bugs are numerous, and their allergens can trigger asthmatic reactions. The misuse of chemicals and other technologies for controlling bed bugs has the potential to have a deleterious impact on human health, while the insect itself can be the cause of significant psychological trauma. The control of bed bugs is challenging and should encompass a multidisciplinary approach utilizing nonchemical means of control and the judicious use of insecticides. For accommodation providers, risk management procedures should be implemented to reduce the potential of bed bug infestations.

The effect of praziquantel applied per os on selected haematological and biochemical indices in common carp (Cyprinus carpio L.)

The aim of the study was to assess the effects of the anthelminthic, praziquantel, on the haematological and biochemical indices of the blood of common carp (Cyprinus carpio L.). Fish were divided into six groups: two groups received 30 mg kg(-1) body weight (bw) of praziquantel, and two groups were given 50 mg kg(-1) bw of praziquantel mixed into the heat-treated amyloid vehicle. Fish in the remaining two groups were given only the amyloid vehicle and were used as controls. Fish were examined either 24 or 96 h after administration. Praziquantel treatment was characterised by a significantly lower erythrocyte count, haemoglobin level, packed cell volume and total protein at both dose levels after 24 h compared with the controls, but these parameters were similar to the control values at 96 h. The activity of alanine aminotransferase (ALT) was significantly higher after 96 h in the treated groups, which could be attributed to slight hepatocyte damage caused by praziquantel. However, the differences between the treated and the control groups were not great, and we presumed that they were reversible.

Scabies

Scabies is an ectoparasite caused by the mite Sarcoptes scabiei var hominis, an obligate human parasite. There are about 300 million cases of scabies in the world each year. Common predisposing factors are overcrowding, immigration, poor hygiene, poor nutritional status, homelessness, dementia, and sexual contact. Direct skin-to-skin contact between 15 and 20 minutes is needed to transfer the mites from one person to another. The diagnosis suspected with a clinical history of itch, worse at night, affecting other family members, clinical distribution, and appearance. Definite diagnosis relies on microscopic identification of the mites, eggs, or fecal pellets with 10% potassium hydroxide, ink enhancement, tetracycline fluorescence tests, or mineral oil; other methods include: epiluminescence light microscopy and S. scabiei DNA. The most commonly used treatment modalities are permethrin and ivermectin. Persistence of symptoms for 2-6 weeks after successful treatment is common. Most recurrences are because of reinfection from untreated contacts.

Distribution of Lindane in Water, Sediment, and Fish from the Warri River of the Niger Delta, Nigeria

This paper is the first attempt to quantify the levels and the distribution pattern of lindane in the surface water, sediment and fish (Chrysichthys furcatus and Tilapia zilli). The samples were collected from three stations (Ovwian, Ekakpamre, and Ovu) of the Warri River in the western Niger Delta of Nigeria in 2006: during the dry (January-April) and wet seasons (May-August). The analysis included a total of 96 samples made up of 24 samples each for water, sediment, and fish. The pesticide levels were analysed using high performance liquid chromatography to elucidate its distribution in various environmental compartments. Residue levels in the matrices ranged from below the detection limit (BDL) to 1.37μg L-1 in water, BDL to 12.66 μg g-1 dry weight (dw) in sediment, BDL to 16.67 μg g-1dw in Chrysichthys furcatus, and BDL to 0.15 μg g-1dw in Tilapia zilli. The observed values were above the ecological benchmarks (0.01 μg L-1) recommended by the Nigerian Environmental Protection Agency and European Union. They were also relatively higher than in previous studies on the Nigerian environment, which calls for regular monitoring of the Niger Delta water bodies.

Scabies: molecular perspectives and therapeutic implications in the face of emerging drug resistance

Limited effective treatments, coupled with recent observations of emerging drug resistance to oral ivermectin and 5% permethrin, raise concerns regarding the future control of scabies, especially in severe cases and in endemic areas where repeated community treatment programs are in place. There is consequently an urgent need to define molecular mechanisms of drug resistance in scabies mites and to develop and assess alternative therapeutic options, such as tea tree oil, in the event of increasing treatment failure. Molecular studies on scabies mites have, until recently, been restricted; however, recent advances are providing new insights into scabies mite biology and genetic mechanisms underlying drug resistance. These may assist in overcoming many of the current difficulties in monitoring treatment efficacy and allow the development of more sensitive tools for monitoring emerging resistance.

Scabies

Scabies is a neglected parasitic disease that is a major public health problem in many resource-poor regions. It causes substantial morbidity from secondary infections and post-infective complications such as acute post-streptococcal glomerulonephritis. Disease control requires treatment of the affected individual and all people they have been in contact with, but is often hampered by inappropriate or delayed diagnosis, poor treatment compliance, and improper use of topical compounds such as permethrin, lindane, or benzyl benzoate. In addition to concerns over toxicity with such compounds, parasite resistance seems to be increasing. Oral ivermectin is an alternative that has been used successfully in community control programmes. Plant derivatives such as turmeric, neem, and tea tree oil are also promising future treatments. The disease is strongly associated with poverty and overcrowding, and the associated stigma can ostracise affected individuals. Treatment of scabies in poor countries needs to integrate drug treatment programmes with efforts to improve the socioeconomic conditions and education programmes to reduce stigma. We expect the future to bring more sensitive and specific clinical and laboratory-based diagnostic methods, as well as new therapeutic strategies.

Treatment of scabies with 5% permethrin cream: results of a German multicenter study

BACKGROUND

Until recently, no prescription drug containing permethrin for the therapy of scabies was available on the German market.Therefore, a 5% permethrin cream formulation (InfectoScab 5%) was tested in a single-arm multi-center study including adults and children from 3 months of age with proven scabies.

PATIENTS AND METHODS

On day 0, patients were treated once with permethrin cream in the study center. Control examinations including dermatoscopy were performed on day 14+/-2 and on day 28+/-3. Patients who were not considered cured or who had contact to individuals with untreated scabies received one further treatment with permethrin cream on day 14+/-2. Itching and local tolerability of the cream were documented in patients' diaries. Side effects were assessed by history, skin inspection and evaluation of patients' notes.

RESULTS

106 patients in 13 centers were enrolled in the study. Their mean age was 29.2 years (range, 141 days to 71.9 years); 34% of them were children or adolescents. 78.3% of patients were either severely (3 body sites) or very severely (4-5 sites) affected. The cure rate on day 28+/-3 was 95.1% (95% confidence interval, 91.0-99.3%). Pruritus declined markedly and continuously. In general, the cream was well tolerated; side effects were almost invariably mild.

CONCLUSIONS

Our results support the efficacy and safety of 5% permethrin cream in adults, children and infants suffering from scabies. These results have contributed to the approval of InfectoScab 5% in Germany for the treatment of scabies in October 2004.

Treatment of scabies: newer perspectives

Scabies is a common dermatological problem managed by general physicians, family physicians, and dermatologists. Scabies manifests itself in various forms in different individuals. The treatment of scabies has undergone developments with the evolution of new treatment strategies and antiectoparasitic drugs. The advent of drugs such as permethrin and ivermectin has revolutionised treatment. Management of scabies not only includes prescribing the drugs but also educating patients properly about the method of application of the drug. Treatment failures may result for various reasons and must be managed appropriately.

Scabies: more than just an irritation

Human scabies, caused by skin infestation with the arthropod mite, Sarcoptes scabiei, typically results in a papular, intensely pruritic eruption involving the interdigital spaces, and flexure creases. Recent research has led to a reassessment of the morbidity attributable to this parasite in endemic communities, particularly resulting from secondary skin sepsis and postinfective complications including glomerulonephritis. This has led to studies of the benefits of community based control programmes, and to concerns regarding the emergence of drug resistance when such strategies are employed. The renewed research interest into the biology of this infection has resulted in the application of molecular tools. This has established that canine and human scabies populations are genetically distinct, a finding with major implications for the formulation of public health control policies. Further research is needed to increase understanding of drug resistance, and to identify new drug targets and potential vaccine candidates.

First documentation of in vivo and in vitro ivermectin resistance in Sarcoptes scabiei

Ivermectin is increasingly being used to treat scabies, especially crusted (Norwegian) scabies. However, treatment failures, recrudescence, and reinfection can occur, even after multiple doses. Ivermectin resistance has been documented for some intestinal helminths in animals with intensive ivermectin exposure. Ivermectin resistance has also been induced in arthropods in laboratory experiments but, to date, has not been documented among arthropods in nature. We report clinical and in vitro evidence of ivermectin resistance in 2 patients with multiple recurrences of crusted scabies who had previously received 30 and 58 doses of ivermectin over 4 and 4.5 years, respectively. As predicted, ivermectin resistance in scabies mites can develop after intensive ivermectin use.

Antiparasitic drugs and lactation: focus on anthelmintics, scabicides, and pediculicides

Infections involving helminths or parasitic worms affect more than 25% of the population worldwide. Because lactating women and their infants are often affected by the complications of these infections such as iron deficiency anemia and malnutrition, they benefit the most from drug therapy. However, scientific literature offers little information regarding transfer of anthelmintics in breast milk and its effects in lactating infants. Scabies and pediculosis, or lice, are common skin infections affecting school-aged children. Close contacts of infected children, which often include lactating mothers, need treatment with one of the several topical products available in the market. This article will review the physicochemical properties and use of anthelmintics, pediculicides, and scabicides while breastfeeding.

[Pediatric dermatotherapy]

Dermatological therapy of children differs considerably from treatment of adults and poses a special challenge. Dermatological diseases often form idiosyncratic entities with a prognosis different from adults and must be treated appropriately. Consideration should also be given to the fact that children occasionally experience adverse reactions to drugs, which are not observed in adults. A selection of dermatological diseases and typical drug reactions are presented to illustrate the special features and differences between pediatric dermatotherapy and treatment of adults.