Prevention of opportunistic infections in immunosuppressed patients in the tropical top end of the Northern Territory

The population of the Top End of the Northern Territory has a high incidence of several infections of particular significance in the immunosuppressed. The following protocol for evaluation and treatment of patients prior to immunosuppression was developed in order to reduce the incidence of serious opportunistic infections. The infections discussed are Strongyloides stercoralis, tuberculosis, scabies, chronic hepatitis B, melioidosis and other bacterial infections. We recommend that all patients planned to receive more than 0.5 mg/kg/day of prednisolone for >14 days, or any more potent immunosuppressive drug, be evaluated and treated according to this protocol. Details of the rationale, evidence base, and proposed investigations and therapy for such patients are discussed.

Identification of a homologue of a house dust mite allergen in a cDNA library from Sarcoptes scabiei var hominis and evaluation of its vaccine potential in a rabbit/S. scabiei var. canis model

Sarcoptes scabiei ("itch mite") causes scabies, a disease of considerable human and veterinary significance. Little work has been done at the molecular level because of the difficulty of obtaining mites. We have used mites in skin from the bedding of crusted scabies patients for the construction of a library of 10(5) cDNAs from S. scabiei var. hominis cloned in the vector pGEX4T-2. We describe the isolation by immunoscreening of 2 clones, one of which (Ssagl) is homologous to and cross-reactive with the house dust mite Euroglyphus maynei allergen M-177, an apolipoprotein from hemolymph. Immunohistochemistry revealed that it is located around the internal organs and cuticle of the mite and in eggs. Although it was not found to be protective in a challenge trial, the rabbits did not exhibit typical crust characteristics. This work shows that it is now possible to conduct such challenge trials with cloned scabies antigens.

Preventing transmission of sarcoptic mange from sows to their offspring by injection of ivermectin. Effects on swine production

A blind and controlled field study was conducted on a pig farm in Australia to evaluate the activity of 1% ivermectin solution when injected into pregnant sows that were naturally infested with mites. The study was designed to appreciate the tolerance of the product on sows (litter size, litter birth weights, litter weaning weights, pre-weaning mortality) and to show the effects of sarcoptic mange on the growth performances of their offspring. Twenty sows were selected and ranked on Day-10, prior to the start of the study, on the basis of positive mite counts and parity. Sows were randomly allocated into two groups, A and B. On Day-7, they were injected once with product A (1 ml/33 kg; yielding 300 microg ivermectin/kg BW) or product B (placebo), respectively and then moved to the farrowing unit. Mite counts, ear and body lesions were scored and recorded. The average daily weight gain (ADG) was calculated on piglets from birth to Day-45 (ADG(45)) and birth to Day-70 (ADG(70)). Ivermectin was 100% efficient in preventing the transmission of scabies mites and did not have negative effect on the pregnant sows. Growth performances (ADG(45) and ADG(70)) of piglets from treated sows were significantly higher (452 and 541.5 g per day) than that from untreated sows (433.5 and 518.4 g per day) respectively, confirming that sarcoptic mange is detrimental to the production performances of growing pigs.

Factors supporting sustainability of a community-based scabies control program

Scabies remains a major problem in Aboriginal communities within the Northern Territory of Australia. Secondary skin infection with Group A streptococcus (GAS) is very common and post-streptococcal disease rates remain high. Treating families in isolation will have only limited success, as reinfection frequently occurs as a result of the high levels of movement between households and communities. We describe the results of a successful community intervention to reduce scabies and GAS skin infection in one of the largest Aboriginal communities in the Northern Territory, 15 months post-intervention, and we discuss factors that have led to the success and sustainability of the program.

[The risk of contagious epidemics in geriatric facilities]

THE RISKS OF EPIDEMICS IN INSTITUTIONAL SETTINGS: An epidemic must be suspected when an increase in the number of cases of a same type of infection is observed. Numerous microorganisms are responsible for epidemics in geriatric facilities: viruses, bacteria and parasites. In the case of an epidemic, a certain number of specific measures must be taken in order to prevent the transmission of infection and eradicate the epidemic. IN THE CASE OF INFLUENZA: Other than the vaccination of elderly institutional residents, that of the nursing staff appears essential. If a severe epidemic occurs, specific antivirals can be used, three of which are already available. IN THE CASE OF PNEUMOCOCCI: Examples of epidemics of pneumococcal infections in elderly institutional residents in the United States underlines the interest of pneumococcal vaccines, particularly since the strain responsible corresponded to a serotype contained in the 23 valence vaccine. WITH REGARD TO SCABIES: All the patients and all the staff must be treated on the same day and at the same time their clothing and bed linen. All persons in contact with the patient, the families and friends of the staff, their clothes and the environement must be treated.

Control of transmission of Norwegian scabies

Seven staff members developed scabies after exposure to a patient with acquired immunodeficiency syndrome (AIDS) dementia and hyperkeratotic skin lesions. They were treated and prophylaxis was given to 11 staff members in September 1998. The hospital has had no nosocomial scabies since then despite the admission of 11 patients with AIDS and Norwegian scabies.

Outcome of an interventional program for scabies in an Indigenous community

OBJECTIVE

To implement an intervention program for reducing the prevalence of scabies in a large Northern Territory Aboriginal community.

DESIGN

Prospective, longitudinal screening, intervention and follow-up study.

PARTICIPANTS AND SETTING

All children aged 5 years and under in one of the largest Aboriginal communities in the Northern Territory, total population, approximately 2,200 (95% Indigenous).

MAIN OUTCOME MEASURES

A decrease in prevalence of scabies, infected scabies and non-scabies pyoderma over seven months.

RESULTS

The number of children aged 5 years and under screened intially and at the three follow-up screenings ranged from 201 to 242 (more than 98% of those eligible on each occasion). The prevalences of scabies, infected scabies and non-scabies pyoderma before intervention were 35%, 12% and 11%, respectively. At 6 weeks postintervention these had decreased to 3%, 1% and 4%, respectively; low prevalences were maintained at four and seven months.

CONCLUSIONS

This intervention, which was based on community motivation, involvement and control, successfully reduced the prevalence of scabies. Continuing community health education and regular screening will be crucial in controlling scabies. The methods and results of this study may be helpful in developing a coordinated program for all remote Aboriginal communities in the area.

Preventing transmission of Sarcoptes scabiei var. suis from infested sows to nursing piglets by a prefarrowing treatment with doramectin injectable solution

Studies were conducted at swine facilities in Illinois and North Carolina to evaluate the effect of treatment with doramectin injectable solution on transmission prevention of Sarcoptes scabiei var. suis from sows to nursing piglets. Approximately 42 days prefarrowing, 58 mange-free sows were experimentally infested with 200 S. scabiei in each ear. Seven to fourteen days prior to farrowing, 22 sows were given doramectin injectable intramuscularly at a dose of 300 microg/kg of body weight. A total of 21 sows served as untreated controls. Skin scrapings for mite counts and lesion scoring were performed on sows before treatment on day 21, and on either day 35 or 42. Each sow was observed on days 0, 7, 14, 21, 28, and 35 or 42 for the incidence of scratching/rubbing. Skin scrapings, lesion scoring, and observation of scratching/rubbing were performed on the piglets after weaning and at the end of the nursery stage. Geometric mean mite counts of the untreated sows were 0.70 and 0.26 on days 21 and 35 or 42, respectively, and 0.00 for doramectin-treated sows over the same time periods (P<0.05). Lesions scores and the incidence of scratching/rubbing were both higher in the untreated sows as compared to the doramectin-treated sows during the same time periods (P<0.05). Geometric mean mite counts of piglets farrowed by untreated sows were 0.50 and 0.60 after weaning and at the end of the nursery stage, respectively, and 0.00 for piglets from doramectin-treated sows over the same time periods (P>0.05). Lesion scores and the incidence of scratching/rubbing were both higher in piglets from untreated sows as compared to those piglets from doramectin-treated sows (P<0.05). Treating S. scabiei-infested sows with doramectin injectable solution before farrowing eliminated mite infestation and prevented the transmission of S. scabiei to piglets.

[Informational support of the scabies control system in Moscow]

The paper describes the basic elements of informational provision of the scabies control system in Moscow which are presented as 3 components (sections): statistic, dynamic, and prognostic. Comparing the statistic and dynamic components of informational flows allows one to predict (a prognostic component) the evolution of the scabies epidemiological situation and the most promising trends in the improvement of the scabies control system in Moscow.

[Preliminary analysis of the incidence rate of scabies in Lódź population]

We have analysed all the reported and diagnosed cases of scabies in the years 1999-2000 per 100 000 inhabitants in the Lódź voivodeship. The data was obtained from the Regional Administration Unit for the Control of Epidemics and Hygiene Promotion in Lódź. The incidence in Lódź voivodeship was found to be twice as high (89,0) as that in Poland (44,0). The highest incidence in Lódź voivodeship was found in Radomsko (268,0), Pabianice (149,0) and Kutno (148.5) districts. The number of new cases registered in 1999-2000 did not increase in the districts: Leczyca, Radomsko, Lowicz and Bełchatów.

[The importance of different pig diseases in the Netherlands]

As part of the project 'Clean pigs', IPG Institute for Pig Genetics BV made an inventory of the impact of different diseases on the Dutch pig industry. An expert panel assessed the importance of the different diseases with regard to public health, farm economy, the pig sector and export sales. The possibilities for the diagnosis of the different pathogens were listed and the goal for the next years, was set. Diseases were classified into three categories, according to their importance for the Dutch pig industry (Table 2). The diseases that can be eradicated are Salmonella (only specific strains), Pasteurella multocida DNT + PAR), Actinobacillus pleuropneumoniae, Haematopinus suis (lice) and Sarcoptes scabei (var. suis) (mange). National introduction of list A en most list B diseases of the OIE classification must be prevented.

Skin infections and infestations in Aboriginal communities in northern Australia

The most important skin infections in Aboriginal communities in central and northern Australia are scabies and streptococcal pyoderma. Scabies is endemic in many remote Aboriginal communities, with prevalences in children up to 50%. The cycles of scabies transmission underlie much of the pyoderma. Up to 70% of children have skin sores, with group A streptococcus (GAS) the major pathogen. Group A streptococcus is responsible for the continuing outbreaks of post-streptococcal glomerulonephritis and acute rheumatic fever (ARF). The cycles of scabies transmission in dogs and humans do not appear to significantly overlap. Guidelines have been developed for community control of scabies and skin sores and successful community initiated coordinated programmes have occurred. The anthropophilic dermatophyte Trichophyton rubrum is ubiquitous in many communities, again reflecting living conditions. Other skin infections related to the tropical environment include melioidosis, nocardiosis, Chromobacterium violaceum and chromoblastomycosis. Sustainable and long-term improvements in scabies, skin sores and GAS-related disease and tinea require fundamental changes that address social and economic inequities and, in particular, living conditions and overcrowding.

Effects of psoroptes ovis infection and its control with an ivermectin controlled-release capsule on growing sheep. 1. Evaluation of weight gain, feed consumption and carcass value

To evaluate the prophylactic and therapeutic effects of an ivermectin controlled-release capsule (IVM-CRC) on the productivity of growing sheep infested with Psoroptes ovis 24 male and 24 female Merino landrace lambs, 5-6 months old and weighing 21.2-35.0 kg, were used. Sixteen replicates of three animals were formed based on sex and Day 0 body weight. Within each replicate animals were randomly allocated to one of three groups: untreated control; IVM-CRC on Day 0; IVM-CRC on Day 84. For treatment an IVM-CRC for sheep weighing 20-45 kg was used which is designed to deliver ivermectin at a minimum dose of 20 microg/kg per day for 100 days. The lambs were infested with 50-60 P. ovis mites each on Days 14 and 21. Mites in skin scrapings were counted on Days 70, 84, 98, 112 and 126. Body weight and feed consumption were measured every 2 weeks from Day 0 to 126. The animals were slaughtered on Day 127 and their carcasses evaluated. The IVM-CRC treatment on Day 0 prevented the establishment of P. ovis. All untreated lambs became infested. The lambs treated with an IVM-CRC on Day 84 became mite-free from Day 112 onwards. The lambs treated on Day 0 had significantly (p<0.05) greater body weight gain from Day 0 to 84 (13.9 kg) and Day 0 to 126 (20.9 kg) than the untreated controls (9.6 and 12.8 kg, respectively) and the sheep treated on Day 84 (8.4 and 14.9 kg, respectively). Feed consumption (Days 0-126) for sheep treated with the IVM-CRC on Day 0 was higher than for sheep treated on Day 84 (p<0.05) and for the untreated controls (p<0.1). The carcasses of sheep treated with the IVM-CRC on Day 0 had significantly (p<0.05) higher warm and cold weights, carcass yield, rib eye area and back fat thickness than the untreated control group and the sheep treated with the IVM-CRC on Day 84. The sheep treated with the ivermectin CRC on either Day 0 or 84 had significantly (p<0.05) better muscle scores and lower muscle pH 1h post-slaughter than the untreated controls. There was no significant (p>0.1) difference between warm and cold carcass weights, carcass yield and rib eye area between sheep treated on Day 84 and untreated controls.

Effects of Psoroptes ovis infection and its control with an ivermectin controlled-release capsule on growing sheep. 2. Evaluation of wool production and leather value

To evaluate the prophylactic and therapeutic effects of an ivermectin controlled-release capsule (IVM-CRC) on the productivity of growing sheep infested with Psoroptes ovis 24 male and 24 female Merino landrace lambs, 5-6 months old and weighing 21.2-35.0 kg, were used. Sixteen replicates of three animals were formed based on sex and Day 0 body weight. Within each replicate animals were randomly allocated to one of three groups: untreated control; IVM-CRC on Day 0; IVM-CRC on Day 84. For treatment an IVM-CRC for sheep weighing 20-45 kg was used which is designed to deliver ivermectin at a minimum dose of 20 microg/kg/day for 100 days. The lambs were infested with 50-60 P. ovis mites each on days 14 and 21. The animals were shorn on Day 126. After slaughter on Day 127 the quality of the leather produced from their skins was evaluated. The IVM-CRC treatment on Day 0 prevented the establishment of P. ovis. All untreated lambs became infested. The lambs treated with an IVM-CRC on Day 84 became mite-free from Day 112 onwards. The lambs which were treated on Day 0 had significantly (p<0.05) greater clean fleece weight (1.5 kg) and fleece yield (52.1%) than the untreated controls (0.9 kg and 34.1%, respectively) or than lambs treated on Day 84 (1.0 kg and 47.8%, respectively). Clean fleece weight and fleece yield were in the tendency (p=0.055) or significantly (p<0. 001) greater, respectively, for lambs treated on Day 84 than for the untreated controls. The chrome tanned dried crust leather of all untreated controls and six of the 16 lambs treated on Day 84 showed grain surface defects such as discolourations, indurations and coarse, pitted grain. The useful (defect-free) leather size was significantly (p<0.01) higher for the lambs treated on Day 0 (100%) than for the lambs treated on Day 84 (82.7%) and the untreated controls (7.8%). The physical testing revealed that the leather of sheep treated on Day 0 had significantly (p<0.05) higher thickness, elongation break and tear resistance than the leather of both untreated controls and sheep treated on Day 84. There were no significant differences in the physical characteristics of the leather of the untreated controls and the sheep treated on Day 84.

Serum antibody to Sarcoptes scabiei and house dust mite prior to and during infestation with S. scabiei

In this study, serum antibodies to Sarcoptes scabiei var. canis (SS), Dermatophagoides farinae (DF), and D. pteronyssinus (DP) were determined in 19 healthy, random-source dogs prior to infestation with scabies then again during a primary infestation, cure and challenge infestation with scabies. Prior to scabies infestation, serum of 11 dogs contained faintly detectable amounts of IgE and/or IgG to proteins in SS extract, probably resulting from sensitization to dust mites that share cross-reactive antigenic epitopes with SS. After becoming infested with scabies, the response to SS antigens became stronger with antibodies appearing to more antigens as the scabies infestation progressed. Three of the newly recognized proteins were 170, 155 and 142/133kD and could be used in a diagnostic test since antibodies to them appeared during the primary infestation. In addition, during the primary infestation, 14 of 15 dogs developed IgE to 1-11 new SS proteins in addition to an increase in IgE binding to those proteins recognized prior to infestation. Overall, the strongest antibody responses (IgE and IgG) were exhibited during cure of the first infestation, when dead mites were still present in the stratum corneum. As expected, the antibody response was strong and rapid during challenge when the infestation self-cured. The immunogenic SS proteins identified by serum antibody binding during challenge, when the hosts self-cured, are candidates for inclusion in a vaccine. These candidate proteins are 200, 185, 170, 155, 142/133, 112, 97, 74, 57, 45/42, 32 and 22kD. Some of the proteins in SS that exhibited new or increased antibody binding during the experiment also had IgE and IgG binding to proteins with similar molecular weights in DF and DP extracts. These results illustrate the difficulties involved in understanding and interpreting serum antibody for developing a serological test for the diagnosis of scabies, isolating relevant SS antigens that could be included in a vaccine for prevention of scabies, and for understanding the immune response mechanism to scabies.

Outbreak of scabies in Norwegian nursing homes and home care patients: control and prevention

Over a period of five months (October 1998-February 1999), an outbreak of scabies affected 19 persons associated with a nursing home in Oslo, Norway. Scabies was diagnosed in 13 patients; six long-term patients, five short-term patients also cared for at home, and two home care patients associated with the same institution. Six healthcare workers who had assisted with infected patients in their own homes were also diagnosed with scabies. Two separate index cases were found. Both had had pruritus for several months, diagnosed as eczema, and were repeatedly treated at dermatology outpatient clinics before the diagnosis was made. Both index cases were cared for at home and in the nursing home (short-term). Repeated treatments with permethrin were tried before effective treatment with benzyl benzoate. Altogether 370 persons (patients, staff, relatives) were treated. In June-July 1999, scabies was diagnosed in two other nursing homes; six patients or staff, and 156 persons were treated. Patients with scabies were contact isolated and disinfection and cleaning was performed. Simultaneous treatment and washing or disinfection of clothing, bedding and environment of all potentially affected individuals is imperative to control an outbreak of scabies.