Human density, economic level and frequency of canine helminths in Buenos Aires.

The aim of this study was to explore through cross-sectional study the variation in the prevalence of parasitic helminths in canine faeces collected from green spaces of Buenos Aires according to the human density (HD) and economic level (EL) in the surroundings. HD and EL were considered as independent variables with three categories each. Twenty public squares (one hectare of surface) were randomly selected for each existing combination of the two independent variables. Ten random samples of fresh canine faeces were obtained in each square and analysed for helminths by the sedimentation and flotation techniques. The prevalence for each of the species was analysed using generalized linear models (GLM). The prevalence was modelled with a binomial error distribution and a logit link function. Helminth eggs were detected in 45 out of the 200 (22.5%) faecal samples collected and in 18 of the 20 green spaces sampled. The species observed were Ancylostoma caninum (13% of samples), Trichuris vulpis (8%) and Toxocara canis (4.5%). The GLM indicated that the prevalence of A. caninum in the slum areas (very high HD and very low EL) was higher than that in the other areas studied. However, the HD seemed to contribute more than the EL to the variations in the prevalence of A. caninum in faecal samples. The GLM showed no differences in the prevalence of the other parasite species for the different levels of the independent variables.

Daylight photodynamic therapy with methyl aminolevulinate cream as a convenient, similarly effective, nearly painless alternative to conventional photodynamic therapy in actinic keratosis treatment: a randomized controlled trial.

BACKGROUND: Daylight photodynamic therapy (DL-PDT) of actinic keratosis (AK) has shown preliminary efficacy and safety results comparable to conventional photodynamic therapy (c-PDT), using methyl aminolevulinate (MAL) cream. OBJECTIVES: To demonstrate the efficacy and safety of DL-PDT vs. c-PDT in treating mild facial/scalp AK. MATERIALS AND METHODS: This 24-week randomized, controlled, investigator-blinded, multicentre, intra-individual efficacy (non-inferiority) and safety (superiority regarding pain) study enrolled 100 subjects. AKs on the face/scalp were treated once, with DL-PDT on one side and c-PDT on the contralateral side. Primary end points for DL-PDT at week 12 were efficacy [non-inferiority regarding complete lesion response (mild AK)] and safety (superiority regarding subject's assessment of pain). Lesions with complete response 12 weeks after one treatment session were followed until week 24. The safety evaluation included incidence of adverse events. Subject satisfaction was classified using a questionnaire. RESULTS: At week 12, the complete lesion response rate with DL-PDT was non-inferior to c-PDT (89·2% vs. 92·8%, respectively; 95% confidence interval -6·8 to -0·3), confirmed by intention-to-treat analysis. Additionally, regardless of the treatment used, 96% of mild lesions were maintained in complete response 24 weeks after the PDT session. For DL-PDT, subject-reported pain was significantly lower (0·8 vs. 5·7, respectively; P < 0·001), with better tolerability and significantly higher subject satisfaction regarding convenience and outcome. CONCLUSIONS: Daylight-mediated PDT was not inferior in efficacy to Metvix c-PDT (mild AK response rate), better tolerated, nearly painless and more convenient for patients.

A clinical study comparing methyl aminolevulinate photodynamic therapy and surgery in small superficial basal cell carcinoma (8-20 mm), with a 12-month follow-up.

OBJECTIVE: To compare the efficacy and cosmetic outcome (CO) of photodynamic therapy with topical methyl aminolevulinate (MAL-PDT) with simple excision surgery for superficial basal cell carcinoma (sBCC) over a 1-year period. METHODS: In this multicentre, randomised, controlled, open study, patients were treated at baseline either with MAL-PDT (two sessions, 7 days apart, repeated 3 months later if incomplete clinical response) or surgery (at baseline). Primary endpoints were clinical lesion response (CR) 3 months after last treatment and CO assessed by the investigator 12 months after last treatment. Secondary endpoints were CR at 12 months (i.e. recurrence) and CO assessed by the investigator at 3 and 6 months and by the patient at 3, 6 and 12 months. RESULTS: Overall, 196 patients were enrolled with 1.4 sBCC lesions on average per patient. Mean lesion count reduction at 3 months was 92.2% with MAL-PDT vs. 99.2% with surgery [per protocol (PP) population] confirming the non-inferiority hypothesis (95% confidence interval, -12.1, -1.9). A total of 92.2% lesions showed CR at 3 months with MAL-PDT vs. 99.2% with surgery (PP population). At 12 months, 9.3% lesions recurred with MAL-PDT and none with surgery. CO was statistically superior for MAL-PDT at all time points. At 12 months, 94.1% lesions treated with MAL-PDT had an excellent or good CO according to the investigator compared with 59.8% with surgery. This difference was confirmed with the patients' assessment. The proportion of excellent CO markedly improved with time with MAL-PDT unlike surgery. CONCLUSIONS: MAL-PDT offers a similarly high efficacy and a much better CO than simple excision surgery in the treatment of sBCC.

Magnitude and distribution of canine fecal contamination and helminth eggs in two areas of different urban structure, Greater Buenos Aires, Argentina.

The canine fecal contamination and the potential transmission of parasites to human and canine populations represent a public health problem of cosmopolitan importance. The objectives of this work were to evaluate the magnitude of fecal and parasite contamination in two suburban areas of different characteristics, and to investigate their distribution in various urban microenvironments such as yards, green spaces and sidewalks. The areas were referred to as middle-income neighbourhood (MIN) and low-income neighbourhood (LIN). To evaluate fecal contamination and its distribution, feces were counted and areas surveyed were calculated. The parasite contamination was evaluated from the prevalence of helminthosis found in a randomly selected fecal sample of the canine population in each of the study areas. The respective median fecal densities in MIN and LIN were 0.11 and 0.12 feces/m2 for green spaces, 0.10 and 0.19 feces/m2 for sidewalks (Mann-Whitney test, p<0.05), and 0.04 and 0.07 feces/m2 for households. In all the surveyed environments, dogs were free-ranging animals and preferred to defecate on grass surfaces rather than on bare soil, tile or sand. In MIN and LIN the respective prevalences were 40% and 70% for helminths in general (Chi square=15.17, p<0.01), 14 and 53% for Ancylostoma (Chi square=23.99, p<0.01), 9 and 17% for Toxocara (p>0.05), and 26 and 38% for Trichuris (p>0.05). Sidewalks were the most contaminated environments in LIN. The level of infected feces in sidewalks and yards was higher in LIN than in MIN (Mann-Whitney test, p<0.05). This study includes a discussion of the influence of variables such as canine population density, sidewalk structure and amount of available green spaces on the distribution of fecal contamination, and results obtained are compared with those previously recorded for Buenos Aires City. An increasing gradient of contamination by canine feces and parasites was observed as socioeconomic status decreased, the canine population increased and the sanitation condition decrease.

Chagas disease in north-west Argentina: association between Trypanosoma cruzi parasitaemia in dogs and cats and infection rates in domestic Triatoma infestans.

The association between Trypanosoma cruzi parasitaemia in dogs and cats and Tryp. cruzi infection rates in domestic Triatoma infestans was studied in a cross-sectional survey of 31 houses (89%) in the rural villages of Trinidad and Mercedes, north-west Argentina, where no spraying of insecticides had ever been done. Similar prevalence rates of parasitaemia, determined by xenodiagnosis, were recorded among 68 dogs (41.2%) and 28 cats (39.3%). Bug infection rates were significantly associated with the presence of infected cats (those with positive xenodiagnosis) stratified by the number of infected dogs (relative risk = RR = 1.90; 95% confidence interval = CI = 1.51-2.38), and with the number of infected dogs stratified by the presence of infected cats (RR = 2.71; CI = 1.81-4.07). The percentage of infected bugs in houses with and without children stratified by the presence of infected dogs or cats was not significantly different (RR = 0.69; CI = 0.45-1.05). The combined effect of infected dogs and infected cats on bug infection rates fitted closely with an additive transmission model. Bug infection rates were significantly higher when infected dogs shared the sleeping areas of people than when they did not (RR = 1.79; CI = 1.1-2.91). Our study showed that infected dogs and infected cats increase the risk of domestic transmission of Tryp. cruzi to T. infestans.

Chagas disease in north-west Argentina: infected dogs as a risk factor for the domestic transmission of Trypanosoma cruzi.

The association between household seroreactivity to Trypanosoma cruzi in dogs and children and T. cruzi infection rates in domestic Triatoma infestans was investigated in 1988-1989 in the rural community of Amamá, north-west Argentina, where house spraying with residual pyrethroids was carried out in 1985. Three years after spraying, a greater reduction of the average T. cruzi prevalence rate in dogs (from 83% to 40%) than in children (from 48% to 30%) was accompanied by a substantial decrease in vector infection rates from 51%-63% to 21%. At a household level, in homes with or without seroreactive children, the percentage of infected T. infestans was 4.5-4.7 times higher when seroreactive dogs were present (27.1%-34.8%) than when they were not (5.8%-7.7%; stratified relative risk [RR] = 4.58). The contribution of seroreactive children to bug infection rates was not significant (RR = 1.29). The combined effect of both seroreactive dogs and seroreactive children fitted equally well with additive or multiplicative transmission models. Bug infection rates showed an increasing trend with the number of seroreactive dogs and an inverse association with the age of the youngest seroreactive dog. Our study supports the hypothesis of a causal association between the presence and number of infected dogs and increased levels of T. cruzi transmission to domestic T. infestans.

Epidemiology of Toxocara canis in the dog population from two areas of different socioeconomic status, Greater Buenos Aires, Argentina.

Toxocara canis infection in dogs is a public health problem in most countries, although it has been poorly documented in many of them. The main objective of the present work was to investigate the epidemiology of infection in the canine populations from two areas of Buenos Aires of different socioeconomic status and urban conditions: a middle-income neighbourhood (MIN) and a low-income neighbourhood (LIN). This study evaluated the prevalence of infection in dogs by parasitological and serological techniques in both areas, and described the relationship between the infection and different epidemiological variables for each neighbourhood. A cross-sectional study was carried out after a house-to-house census was completed. During August 1999, a sample of households was selected at random (nMIN=53 and nPA=52). In each house, one dog was randomly chosen for the collection of fresh faeces and blood. The dog owners were interviewed utilising a questionnaire about dogs on sex, recent anthelmintic treatment, degree of confinement, control by the dog's owner (whether the dog goes out of the house accompanied or not, leashed or unleashed), defecation site, defecation substratum and number of dogs in the house. The diagnostic techniques were concentration-sedimentation formalin/ether method and ELISA test. The parasitological prevalences in dogs were 9% (5/53) in MIN and 19% (10/52) in LIN, and serological prevalences were 22% (2/9) in MIN and 40% (15/37) in LIN. In MIN, the patent infection of males was significantly higher than that of females. In LIN, puppies less than 1 year old were the most prevalent age class. Our serological results showed that the positivity of adult dogs was more frequent in LIN than in MIN. The density of puppies with patent infection was seven times higher in LIN than in MIN, when combining coprological analysis and the estimated age structure obtained by the census.

Lost to follow up: contributing factors and challenges in South African patients on antiretroviral therapy.

BACKGROUND: Patients who do not return for follow-up at clinics providing comprehensive HIV/AIDS care require special attention. This is particularly true where resources are limited and clinic loads are high. Themba Lethu Clinic at Helen Joseph Hospital in Johannesburg is a facility supported by PEPFAR funding through Right to Care (Grant CA-574-A-00-02-00018); more than 800 HIV/AIDS patients are seen there each week. Data on a sample of patients who failed to return for follow-up were analysed to identify the causes and to plan strategies to overcome the problem. METHODS: A group of 182 patients who missed follow-up appointments at the clinic were identified. Their files were examined to identify possible contributing factors. The patients were then contacted telephonically and asked their reasons for non-attendance. RESULTS: Results show that the leading cause of failure to follow up was financial (34% of patients). Patients cited transport costs and having to pay to open a file at each visit as the biggest monetary obstacles to obtaining treatment. Fifty-five per cent of patients lost to follow-up showed an improvement in CD4 count on treatment. Death accounted for 27% of the patients lost to follow-up and the mean ( +/- standard deviation (SD)) duration of treatment in this group was only 8 ( +/- 6) weeks. Of the patients in this group who had been seen at 4 months, 60% had failed to respond to treatment. The mean duration of ARV treatment before being lost to follow-up was 21 ( +/- 28) weeks. The mean CD4+ count was 92 ( +/- 74.5) cells/ microl and the mean number of visits was 3.33 ( +/- 2.17). Seventy-four per cent of the patients were on regimen 1A, and only 1 cited side-effects of medication as a reason for not returning. CONCLUSIONS: This study highlighted financial difficulty as the major obstacle to obtaining treatment. There is evidence in support of providing ARV treatment free of charge to HIVpositive patients who qualify, as occurs in other provinces in South Africa. It is also suggested that providing ARV therapy at more local clinics in the community would make treatment more accessible. Provision of several months' supply of medicines per visit would help to reduce transport costs and minimise patient expenditure. These interventions may reduce the incidence of patients lost to follow-up in this community.

Folliculotropic T-cell lymphocytosis (mucin-poor follicular mucinosis).

A 48-year-old man presented with multiple asymptomatic patches of hair loss over his trunk and limbs associated with focal keratotic follicular plugs. Multiple skin biopsies showed a panfollicular lymphocytic infiltrate associated with follicular hyperkeratinization, minimal follicular spongiosis, focal basaloid follicular hyperplasia but no overt follicular mucinosis. The lymphocytes were small and there was no atypia. Immunoperoxidase stains showed that the follicular lymphocytes were T cells and predominantly CD4 positive with HLADr (LN3) expressed on their surface. There were insufficient clinical or histopathological features to make a diagnosis of folliculotropic T-cell lymphoma. This case currently may be classified best as folliculotropic T-cell lymphocytosis and may represent a mucin-poor counterpart of follicular mucinosis. Such cases may pursue an indolent course or may evolve to folliculotropic T-cell lymphoma, mycosis fungoides or anaplastic lymphoma. The term folliculotropic T-cell lymphocytosis may be useful for similar cases lacking clinical or histological criteria for lymphoma and lacking follicular mucinosis.

Allergic contact dermatitis to ethoxyquin in a farmer handling chicken feeds.

Farm workers handling animal feeds are exposed to a variety of chemicals, some of which may cause allergic contact dermatitis. A case of allergy to ethoxyquin (a preservative added to chicken feed to inhibit vitamin degradation) in a chicken farmer is presented. Although the offending allergen was identified in this patient, it proved difficult to find ethoxyquin-free chicken feed products and the patient's dermatitis persisted. When facing the clinical problem of dermatitis in animal workers, the possibility of allergic contact dermatitis to components in animal feeds must be considered.

Allergic contact dermatitis in dentistry.

Allergic contact dermatitis (ACD) in dentistry may affect dentists and orthodontists, technicians, nurses and patients. Changes to dental practice in recent years have altered the reported frequencies of allergens causing ACD in both dental personnel and patients. Allergic contact dermatitis to medicaments, metals and glutaraldehyde were previously common allergens in dentistry; however, widespread adoption of rubber gloves by staff has resulted in a significant increase in ACD to glove allergens in both dental staff and their patients, while affording protection against the traditional allergens. Both public concerns about potential toxicity of metals in oral restorations and a greater demand for cosmetic dentistry, have resulted in greater use of acrylics and resins by dental personnel, exposing them to highly allergenic materials. Dermatologists need to be aware of the newer allergenic materials used in dentistry in order to correctly manage skin diseases in this high-risk group.

Tea tree oil allergy: what is the offending agent? Report of three cases of tea tree oil allergy and review of the literature.

Tea tree oil is currently enjoying popularity as a 'cure-all' for a variety of skin conditions, from infections to psoriasis, and many household and personal products containing Melaleuca oil are available. However, despite its chemical complexities and enthusiastic use, there have been only a few reports of allergic reactions to tea tree oil. At the Skin and Cancer Foundation (Sydney, NSW, Australia), three of 28 normal volunteers tested strongly positive to patch testing with tea tree oil. Following further patch testing with tea tree oil constituents, all three patients reacted strongly to two preparations containing sesquiterpenoid fractions of the oil. Because patients often neglect to mention that they have used 'natural' remedies, it is important that physicians are aware of the potential adverse effects of these products. Furthermore, identification of the allergenic ingredients in tea tree oil may assist the growing industry to produce safer products.

Mid-dermal elastophagocytosis presenting as a persistent reticulate erythema.

Two men are presented with a widespread persistent reticulate erythema concentrated within the chronically sun-damaged skin on their trunk. A fine papular element was present in one case and both lacked annular lesions. One patient was human immunodeficiency virus positive. Multiple skin biopsies showed an interstitial infiltrate of histiocytes containing multiple elastic fibres in the upper dermis. There was scant perivascular lymphocytic inflammation but no evident necrobiosis or palisaded granulomas seen typically with granuloma annulare. Elastic stains showed focal mid-dermal elastolysis. Diffuse reticulate erythema in sun-damaged skin may be a clinical marker for elastophagocytosis. This presentation differs from that previously described with actinic granuloma, diffuse granuloma annulare or the inflammatory phase of mid-dermal elastolysis and expands the clinical spectrum of this phenomenon.

Bioactive tumour necrosis factor alpha but not granulocyte-macrophage colony-stimulating factor correlates inversely with Langerhans's cell numbers in skin tumours.

Langerhans' cells (LCs) are thought to play an important role in presentation of tumour antigens for the induction of anti-tumour immunity. Epidermis overlying some transplanted murine skin tumours contains increased numbers of LCs; however, alterations in LC numbers are not related to tumour antigenicity or host immunity, suggesting that another factor(s), such as tumour-produced cytokines, influences LC density. It has been postulated that dendritic epidermal T cells (DETCs) play a role in immunosurveillance within the normal epidermis. Two cytokines which potentially alter LC numbers or function include granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumour necrosis factor-alpha (TNF-alpha). GM-CSF maintains LC viability in culture, and there are reports that it can increase LC density. There is evidence that TNF-alpha induces LC to migrate from the epidermis. In the present study, LC densities in regressor and non-regressor murine skin tumours and overlying epidermis were enumerated, and bioactive GM-CSF and TNF-alpha present in the tumours were measured. We found significantly increased epidermal LC numbers above non-regressor, but not regressor, tumours. DETC numbers were significantly increased above some tumours. Although all tumour types produced TNF-alpha, the regressors, which did not increase LC numbers, produced the most TNF-alpha. In contrast, tumour production of GM-CSF did not correlate with any pattern of alteration of LC density or tumour growth. Tumour production of neither cytokine nor tumour growth correlated with DETC numbers overlying tumours. Our results suggest that TNF-alpha may be associated with skin tumour regression and may prevent LC accumulation by tumours.

Determinants of the domiciliary density of Triatoma infestans, vector of Chagas disease.

In two heavily infested rural villages of Santiago del Estero, Argentina, where no indoor-spraying with residual insecticides had ever been carried out by official control services, we studied the influence of roof and wall structure, domestic use of insecticide, family size and the number of domestic dogs, on the domiciliary density of Triatoma infestans (Klug). Bug density was significantly associated with (1) the interaction between insecticide use and type of roof, (2) the structure of indoor walls, (3) the number of dogs sharing sleeping areas of people (room-mate dogs), and (4) the number of people plus room-mate dogs, but not with just the number of people resident in the house. The interaction between insecticide use and a roof made of 'simbol', a locally available grass (Pennisetum sp.), also reflected a younger age structure of domestic bug populations. In infested houses, the density of bugs infected with Trypanosoma cruzi Chagas was significantly correlated with overall bug density. Our data suggest that the application of environmental management measures by the affected people, such as plastering of walls and modification of roofs, coupled with keeping dogs away from bedrooms and application of insecticides, should limit the domestic population density of T. infestans and thus reduce the transmission of T. cruzi to people.

The leachate composition of an old waste dump connected to groundwater: Influence of the reclamation works.

This study has been carried out in an uncontrolled dump in the suburbs of Buenos Aires, Argentina. This dump still contains solid wastes of different types in direct contact with the human consumption aquifer. After 18 years of overturning the dump was closed in 1992, and the reclamation works started.Three leachate samplings were carried out in three different zones of the dump, selected according to the topography, the age of residues and the degree of water contact. These samplings were done before the reclamation works, at the end, and four months after they were finished. Several chemical parameters, including heavy metals in solid and dissolved fractions, were analyzed.Multivariate analysis (PCA) was performed to help to understand the effects of the labors on leachate composition. The works could be responsible for a temporal increase of dissolved heavy metals and several chemical variables in the leachate. At the sites of the dump where the modifications were carried out, the levels of some elements analyzed recovered their former values a few months after the reclamations works. At the farthest site, the impact and recovery effects of the works on leachate composition, were delayed.

[Leptospira interrogans in a canine population of Greater Buenos Aires: variables associated with seropositivity]. / Leptospira interrogans en una población canina del Gran Buenos Aires: variables asociadas con la seropositividad.

We determined the seroprevalence of leptospirosis in a suburban canine population for the purpose of analyzing the association between different individual and environmental variables and seropositivity for leptospirosis. The study, which was cross-sectional, was performed in July 1992 in a neighborhood of Greater Buenos Aires with approximately 9,500 inhabitants and a canine population of around 2,000 animals. We studied a random sample of 223 dogs and obtained a blood sample from each. Each animal's epidemiologic history was obtained by interviewing the housewife. Serologic measurements were performed by the microagglutination technique with the use of 10 different serotypes of Leptospira interrogans. Of the 223 dogs that were tested, 57% showed seropositivity; 82% of the positive sera coagglutinated with two or more serotypes. The most frequently detected serotypes were canicola and pyrogenes. Seroprevalence in females was less common than in males (P < 0.05) and in puppies less than 1 year old it was less common than in older animals (P < 0.01). Street behavior in the dog and the presence of stagnant water in front of the owner's dwelling were the most important of the risk factors examined. The associations between seropositivity on the one hand and contact with trash deposits, hunting behavior and the presence of rodents inside the dwelling on the other were not statistically significant. Different control measures are discussed.

Dermal myiasis in an Australian traveller.

Myiasis, the infestation of body tissues by the larvae of flies, occurs infrequently in Australian tourists who return from areas where certain species are endemic. Some of these insect species such as Cochliomyia hominivorax and Chrysoma bezziana (New and Old World screw-worms respectively) are responsible for significant disease in livestock as well as in humans. We report a patient who travelled extensively through South America and returned to Australia with a subcutaneous nodule containing a large larva of the species Dermatobia hominis. Because of the risk of travellers introducing unwanted species of flies into our country, it is important for doctors to suspect the possibility of furuncular myiasis, and to obtain accurate identification of the larva.

Generalised granuloma annulare successfully treated with pentoxifylline.

Generalised granuloma annulare (GA) is a chronic disease of unknown aetiology and is recalcitrant to many treatment regimes. Some investigators have suggested that an immune medicated vasculitis may be involved in the pathogenesis of GA. We describe a patient with a ten year history of generalised GA, who showed dramatic clearing of the majority of papules after four weeks of treatment with pentoxifylline. This drug has shown promising results in the treatment of many dermatologic disorders including necrobiosis lipoidica diabeticorum, leukocytoclastic vasculitis and Raynaud's phenomenon. Pentoxifylline is thought to reduce blood viscosity via effects on all major blood components, and its clinical effectiveness in generalised GA lends support to a model of immune-medicated vasculitis in the pathogenesis of this disorder. Thus, pentoxifylline offers a well-tolerated and effective alternative to the treatment options available for patients with granuloma annulare.