Human scabies from contact with water buffaloes infested with Sarcoptes scabiei var. bubalis

Zoonotic Episodes of Scabies: A Global Overview

Zoonotic scabies (ZS), also referred to as “pseudoscabies”, is considered a self-limiting disease with a short incubation period and transient clinical skin signs. It is commonly thought that Sarcoptes scabiei mites from animals are unable to successfully reproduce and persist on human skin; however, several ZS case reports have mentioned the persistence of symptoms and occasionally mites for weeks. The aim of this review was to collect and organize the sparse literature explicitly referring to S. scabiei zoonotic transmission, focusing on the source of the outbreak, the circumstances leading to the transmission of the parasite, the diagnosis including the identification of the Sarcoptes “strain” involved, and the applied treatments. A total of 46 articles, one conference abstract and a book were collected describing ZS cases associated with twenty animal hosts in five continents. Dogs were by far the most common source among pet owners, while diverse livestock and wildlife contributed to the caseload as an occupational disease. Genetic epidemiological studies of ZS outbreaks are still limited in number, but tools are available to fill this knowledge gap in the near future. Further research is also needed to understand the apparent heterogeneity in the morbidity, disease severity and timing of the response to treatment among people infected with different animal-derived strains.

A Serosurvey of Multiple Pathogens in American Black Bears (Ursus americanus) in Pennsylvania, USA Indicates a Lack of Association with Sarcoptic Mange

Infectious diseases, particularly of wildlife, are intrinsically linked to human and domestic animal health. Reports of sarcoptic mange in black bears (Ursus americanus) are increasing in multiple states in the USA and while the reason is unknown, mange in other species has been associated with immunosuppression from multiple causes. Serum from bears across Pennsylvania were collected to determine the seroprevalence of five pathogens important for animal and/or human health: Canine distemper virus (CDV), canine parvovirus (CPV), canine adenovirus-1 (CAV), Toxoplasma gondii, and Trichinella sp. from bears with sarcoptic mange as well as bears that were clinically normal. Several of these pathogens, particularly canine distemper virus, are associated with immunosuppression and secondary infections in other hosts. In addition to describing the seroprevalence and relating these findings to data from other regions, statistics were performed to determine if antibodies to any of these pathogens were associated with mange in bears. The overall seroprevalence to these pathogens was as follows: CDV 7.1% (17/240), CPV 16% (15/94), CAV 6.9% (6/87), Toxoplasma gondii 64.9% (194/299), and Trichinella spiralis 3.2% (7/220). While there was no association between mange and antibodies to these pathogens, infection with one or more of these pathogens has implications for bears, other wildlife, domestic animal, and human health.

Population identification of Sarcoptes hominis and Sarcoptes canis in China using DNA sequences

There has been no consistent conclusion on whether Sarcoptes mites parasitizing in humans and animals are the same species. To identify Sarcoptes (S.) hominis and S. canis in China, gDNA was extracted from individual mites (five from patients with scabies and five from dogs with mange) for amplification of rDNA ITS2, mtDNA 16S, and cox1 fragment sequences. Then, the sequences obtained were aligned with those from different hosts and geographical locations retrieved from GenBank and sequence analyses were conducted. Phylogenetic trees based on 317-bp mtDNA cox1 showed five distinctive branches (species) of Sarcoptes mites, four for S. hominis (S. hominis Chinese, S. nr. hominis Chinese, S. hominis Australian, and S. hominis Panamanian) and one for S. animal (S. animal). S. animal included mites from nine animal species, with S. canis China, S. canis Australia, and S. canis USA clustering as a subbranch. Further sequence divergence analysis revealed no overlap between intraspecific (≤ 2.6 %) and interspecific (2.6-10.5 %) divergences in 317-bp mtDNA cox1. However, overlap was detected between intra- and interspecific divergences in 311-bp rDNA ITS2 or 275-bp mtDNA 16S when the divergences exceeded 1.0 %, which resulted in failure in identification of Sarcoptes. The results showed that the 317-bp mtDNA cox1 could be used as a DNA barcode for molecular identification of Sarcoptes mites. In addition, geographical isolation was observed between S. hominis Chinese, S. hominis Australian, and S. hominis Panamanian, but not between all S. canis. S. canis and the other S. animal belonged to the same species.

The neglected navigating web of the incomprehensibly emerging and re-emerging Sarcoptes mite

Parasite presence in any ecosystem generates complex navigating webs (Parasite-NW) within the system, through which parasites move from one to another host. The appropriate assimilation of parasite navigating web is pivotal for a better understanding of pathogen flow in the ecosystem, with implications for disease control. Sarcoptes mite has been approached from medical, veterinary, entomological, physiological and, recently, molecular sides, to understand its epidemiological navigating web between isolates from different hosts and geographical regions. The obtained conclusions are still a matter of debate. Sarcoptes navigating web (Sarcoptes-NW) is intricate and uncertain, with unexplainable pathogenic flow. In this review we summarize by which routes, under what conditions and at what levels the Sarcoptes mite moves among its hosts.

Scabies: New Future for a Neglected Disease

Scabies is a disease of global proportions in both human and animal populations, resulting from infestation of the skin with the "itch" mite Sarcoptes scabiei. Despite the availability of effective chemotherapy the intensely itching lesions engender significant morbidity primarily due to secondary sepsis and post-infective complications. Some patients experience an extreme form of the disease, crusted scabies, in which many hundreds of mites may infest the skin causin severe crusting and hyperkeratosis. Overcrowded living conditions and poverty have been identified as significant confounding factors in transmission of the mite in humans. Control is hindered by difficulties with diagnosis, the cost of treatment, evidence for emerging resistance and lack of effective vaccines. Historically research on scabies has been extremely limited because of the difficulty in obtaining sufficient quantities of the organism. Recent molecular approaches have enabled considerable advances in the study of population genetics and transmission dynamics of S. scabiei. However, the most exciting and promising development is the potential exploitation of newly available data from S. scabiei cDNA libraries and EST projects. Ultimately this knowledge may aid early identification of disease, novel forms of chemotherapy, vaccine development and new treatment possibilities for this important but neglected parasite.

Pig handler's itch

Forty-six humans who contacted pigs infested with Sarcoptes scabiei were investigated. Thirty (65.2%) had symptoms of sarcoptes scabies, and S. scabiei mites could be recovered from 20 (66.6%) skin scrapings. Itching was the main symptom. People within the age group of 26-35 years were infested the most. Hands and legs were the most common sites of the lesions, which subsided within 2-3 weeks when the infested pigs were treated and the intimate contact with the pigs was prevented.

Efficacy of ivermectin against mange and gastrointestinal nematodes of buffalo (Bubalus bubalis)

The incidence of mange in dairy buffalo in India has increased significantly in recent years. The authors record an outbreak of mange affecting a dairy herd stocking about 30,000 buffalo and 1000 cows. The mange mites were either Sarcoptes scabiei or Psoroptes ovis, or a mixed infestation of both. The morbidity rate was 5-30% varying from group to group, with 100% in a severely affected group. Signs noticed were progressive dermatitis, alopecia, keratinization, skin thickened and wrinkled, intense itching and marked loss of condition often ending in death. Great losses of young animals from mange and gastrointestinal nematodes are very common in dairy herds in India. In view of their economic importance, the activity of ivermectin against naturally occurring mange and parasitic infections of adult buffalo and buffalo calves was determined. Ivermectin was administered by subcutaneous injection (IVOMEC 1% w/v - MSD AGVET) at a dose of 200 mcg kg-1 body weight. The efficacy was ascertained from the disappearance of mites from skin scrapings and the reduction in numbers of worm eggs in the faeces. The results of the treatment were dramatic: the mites disappeared within 2 weeks of the drug being administered in the majority of animals, with marked improvement in skin lesions. Four buffalo which had their entire body surface affected with mange needed a second dose on Day 28 for complete recovery. The effect on the nematodes was equally spectacular, with infections of Neoascaris vitulorum, Trichostrongylidae, Oesophagostomum spp. and Bunostomum being eliminated within 1 week of treatment.

Human notoedric scabies from contact with cats infested with Notoedres cati

Forty-eight human contacts with cats infested with Notoedres cati were investigated; 30 (62.5%) of the contacts showed symptoms of notoedric scabies, and N. cati mites were recovered from 15 (50%) skin specimens. Intense pruritus without any mite burrows developed within a few hours of initial contact with the infested cats. People within the age group of 26-35 years were frequently infested. Hands and legs were the most common sites of lesions. Prolonged association with the infested cats was responsible for this cutaneous disease. The lesions in infested people subsided when the cats were segregated from humans.

Experimental infection of the one-humped camel (Camelus dromedarius) with Sarcoptes scabiei var. cameli and S. scabiei var. ovis

Camels were experimentally infected with Sarcoptes scabiei var. cameli and S. scabiei var. ovis. The lesions produced by both mites were progressive and similar in extent and severity. The lesions produced by the mites spread mechanically through gnawing and scratching, and eventually covered most of the body of the host. Skin scrapings from the experimental lesions contained many mites of all stages, proving that S. scabiei var. cameli and S. scabiei var. ovis became equally well established, reproducing actively in the experimental lesions in their 'natural' and 'wrong' host respectively. The histopathological changes produced by S. scabiei var. cameli and S. scabiei var. ovis were similar. The lesions comprised thick scab and keratin formation, with mites beneath the scab and keratin, marked haemorrhages and severe degenerative and necrotic changes. Excellent clinical recovery occurred following the application of HCH (BHC) after removal of crusts and detritus with salicylic acid. The incomplete host specificity of Sarcoptes necessitates the complete isolation of healthy from infected animals regardless of the host species.

Incidence of sarcoptic mange in buffaloes in India

The incidence of sarcoptic mange in buffaloes with respect to age, sex, relative humidity and temperature was studied at veterinary clinics and breeding farms in Hisar, India. The disease is more common in animals below the age of one year (19.57%) and decreases with the advancement of age i.e. 3.4% at one to five years and 5.3% in the over five years group. Sex has no bearing on the incidence of the disease. Since female buffalo calves get more attention at the hands of small farmers they are presented more frequently at the veterinary clinics. Fluctuations in environmental temperature affect the incidence of the disease. However, relative humidity showed no correlation. Seasonal incidence at the organised farms was erratic due to the ad hoc treatment to control mange. There is an indication that the winter season is most conducive for the spread of the disease (51.0%), followed by post-monsoon (41.3%), summer (23.1%) and rainy season (11.1%).

Experimental infection of goats with Sarcoptes scabiei var. ovis

Goats were experimentally infected with Sarcoptes scabiei var. ovis from sheep, proving that this mite is not completely host specific. More severe lesions were produced on goats when the mites were applied to lacerated than when applied to scarified or non-scarified areas. Lesions were more pronounced on moistened areas than dry areas, and lesions produced on dry scarified areas resembled those produced on non-scarified moistened ones. Skin scrapings from the experimental lesions in the goats contained numerous mites of all stages, proving that the sheep mites had become well established and were reproducing actively in the experimental lesions. Sever histopathological changes were observed in skin sections, which showed mainly thick scab formation, mites beneath the keratin and severe degenerative and necrotic changes. Treatment of the experimental lesions with Lorexane cream (hexachlorocyclohexane) produced rapid and excellent cure.