Detection of enteric parasite DNA in household and bed dust samples: potential for infection transmission.

BACKGROUND: Enteric parasites are transmitted in households but few studies have sampled inside households for parasites and none have used sensitive molecular methods. METHODS: We collected bed and living room dust samples from households of children participating in a clinical trial of anthelmintic treatment in rural coastal Ecuador. Dust was examined for presence of DNA specific for 11 enteric parasites (Ascaris lumbricoides, Trichuris trichiura, Ancylostoma duodenale, Necator americanus, Strongyloides stercoralis, Toxocara canis and T. cati, Giardia lamblia, Blastocystis hominis, Cryptosporidium spp., and Entamoeba histolytica) by quantitative PCR (qPCR). RESULTS: Of the 38 households sampled, 37 had positive dust for at least one parasite and up to 8 parasites were detected in single samples. Positivity was greatest for B. hominis (79% of household samples) indicating a high level of environmental fecal contamination. Dust positivity rates for individual pathogens were: S. stercoralis (52%), A. lumbricoides (39%), G. lamblia (39%), Toxocara spp. (42%), hookworm (18%) and T. trichiura (8%). DNA for Cryptosporidium spp. and E. histolytica was not detected. Bed dust was more frequently positive than floor samples for all parasites detected. Positivity for A. lumbricoides DNA in bed (adjusted OR: 10.0, 95% CI: 2.0-50.1) but not floor dust (adjusted OR: 3.6, 95% CI: 0.3-37.9) was significantly associated with active infections in children. CONCLUSIONS: To our knowledge, this is the first use of qPCR on environmental samples to detect a wide range of enteric pathogen DNA. Our results indicate widespread contamination of households with parasite DNA and raise the possibility that beds, under conditions of overcrowding in a humid tropical setting, may be a source of transmission.

Risk factors for treatment failure in scabies: a cohort study.

BACKGROUND: Treatment failure, which occurs in about one-third of cases, is considered as a major factor in the increasing incidence of scabies in developed countries. OBJECTIVES: To identify predictors of treatment failure of scabies in ambulatory populations. METHODS: This multicentre study compared the clinical characteristics and treatment modalities between a group of patients with scabies treated successfully and another group who were not cured 3 months after antiscabies treatment. RESULTS: In total 210 patients with a diagnosis of scabies were included, comprising 98 patients in the treatment success group and 112 in the treatment failure group. The main risk factors for treatment failure were (i) the use of only one type of treatment, topical benzyl benzoate (BB) or oral ivermectin, vs. the combination of both treatments [odds ratio (OR) 2·15, 95% confidence interval (CI) 1·22-3·77]; (ii) the use of a single intake (vs. two) of oral ivermectin (OR 10·2. 95% CI 4·49-23·2); (iii) intake of ivermectin during a meal vs. on an empty stomach (OR 4·31, 95% CI 1·89-9·84); (iv) absence of decontamination of furnishings (OR 8·72, 95% CI 3·50-21·8), in particular sofa and cushions (OR 5·90, 95% CI 2·34-14·9), mattresses (OR 4·16, 95% CI 1·35-12·8) or car seats (OR 6·57, 95% CI 3·27-13·2) and (v) absence of written documents explaining treatment modalities (OR 5·18, 95% CI 2·57-10·4). In multivariate analysis, treatment failure was mainly associated with (i) use of a single intake (vs. two) of ivermectin (OR 6·62, 95% CI 2·71-16·2); (ii) use of BB alone vs. two intakes of ivermectin (OR 3·51, 95% CI 1·55-7·95) and (iii) absence of decontamination of furniture with acaricides (OR 5·81, 95% CI 1·96-16·7). CONCLUSIONS: Use of topical BB alone and a single intake (vs. two) of ivermectin are predictors of treatment failure.

The influence of time and distance traveled by bed bugs, Cimex lectularius, on permethrin uptake from treated mattress liners.

BACKGROUND: Residual insecticides interrupt the dispersal of bed bugs (Cimex lectularius, L.), but one of the issues encountered with residual applications is understanding the uptake of active residues by the insect. This study determined permethrin uptake by bed bugs walking on the ActiveGuard® Mattress Liner product, via a combination of video recording in arenas and gas chromatography analyses. RESULTS: The best model for estimating permethrin uptake utilized a covariance model (r2 = 0.469) with two factors: time of exposure (F1,55 = 2.44, P < 0.001) and distance traveled (F1,55 = 0.30, P = 0.0460). Bed bug permethrin uptake was 15.1 (95% CI: 10.3-22.1) ng insect-1 within 1 min exposure, 21.0 (15.0, 31.0) ng insect-1 within 10 min and ≈ 42 (29.8, 60.6) ng insect-1 within ≥50 min exposure. Correcting for percentage recovery, these values would be increased by a factor of 1.21. CONCLUSION: This permethrin-treated fabric provides a surface from which bed bugs begin rapidly to absorb permethrin on contact and within the first 1 cm of travel. Variability in uptake was likely a result of grooming and thigmotaxis, and future work should use quantitative methods to study behaviors and formulations that increase exposure to the toxicant. © 2016 Society of Chemical Industry.

[Investigation on mites and insects breeding status of bed mats in college dormitories in Wuhu City].

OBJECTIVE: To understand the breeding situations of mites and insects from bed mats in dormitories in a college in Wuhu City, so as to provide evidences for improving the prevention and control of mites. METHODS: From March to May, 2015, the dust samples from bed mats in student dormitories were collected and detected for mites and insects by microscopy. In addition, the intervention measures including soaking the mats in the warm water, exposing the mats to the sunlight for a long time and cleaning up the indoor environment were carried out, and the breeding situations of mites and insects before and after the intervention were compared. RESULTS: A total of 428 dust samples from bed mats were collected, and the total infestation rate of mites and insects was 71.03%. There were 11 species of mites and insects identified, among which, the infestation rate of Dermatophagoides farinae (60.05%) was the highest, following by that of Liposcelis bostrychophilus (40.89%) . The infestation rates of Cheyletus malaccensis, Blattisocius sp. and Pyemotes sp. were 9.81%, 3.74% and 1.64%, respectively, and the above mites might cause dermatits. The infestation rates of mites and insects in dust samples from bed mats stored in indoor corner, wardrobe, bed bottom, and the balcony corner were 74.75%, 71.26%, 61.17%, and 77.78%, respectively, and the differences among them were not statistically significant (χ2 = 7.030, P > 0.05) . The detectable rates of mites and insects in dust samples from bed mats with no cover, wrapped with cloth bags, and wrapped with plastic bags were 85.58%, 78.13%, and 14.29%, respectively, and the differences among them were statistically significant (χ2 = 164.303, P < 0.05) . After the intervention, both the infestation rates of mites and insects as well as the average density of mites were decreased, and the differences were statistically significant (χ2 = 45.615, t = 3.203, both P < 0.05) . CONCLUSIONS: The infestation rates of mites and insects in bed mats of the dormitories in the college of Wuhu City are high, and among all the species of mites infested, D. farina are preponderant. The intervention measures, such as prepacking bed mats by adequate sealing, soaking bed mats in the warm water, exposing the bed mats to the sunlight and cleaning indoor environment, have an inhibiting effect to the infestation of mites and insects.

House dust-mite allergen exposure is associated with serum specific IgE but not with respiratory outcomes.

Exposure to house dust has been associated with asthma in adults, and this is commonly interpreted as a direct immunologic response to dust-mite allergens in those who are IgE sensitized to house dust-mite. Mattress house dust-mite concentrations were measured in a population-based sample of 2890 adults aged between 27 and 56 years living in 22 centers in 10 countries. Generalized linear mixed models were employed to explore the association of respiratory symptoms with house dust-mite concentrations, adjusting for individual and household confounders. There was no overall association of respiratory outcomes with measured house dust-mite concentrations, even in those who reported they had symptoms on exposure to dust and those who had physician-diagnosed asthma. However, there was a positive association of high serum specific IgE levels to HDM (>3.5 kUA /l) with mattress house dust-mite concentrations and a negative association of sensitization to cat with increasing house dust-mite concentrations. In conclusion, there was no evidence that respiratory symptoms in adults were associated with exposure to house dust-mite allergen in the mattress, but an association of house mite with strong sensitization was observed.

[Identification of house dust mite fauna from allergic patients' mattress in six Mexican states]. / Identificación de la fauna de ácaros del polvo doméstico en colchones de pacientes alérgicos de seis estados mexicanos.

BACKGROUND: House dust is considered an important source of aeroallergens, and the mites living there, are the main cause of allergy to it. In México, there have been few about house dust fauna, and mostly limited to México City. OBJECTIVE: To describe the house dust fauna from mattresses of allergic patients from different cities in México. METHODS: Sixty dust samples were collected from mattresses in 6 Mexican states: Oaxaca, Tamaulipas, Veracruz, Puebla, Chiapas and Campeche. Mites were isolated under a stereomicroscope using lactic acid -0.9% NaCI solution. Identification was performed on fixed slides prepared with Hoyer solution. Skin Tests were already performed with allergen extracts of different house dust mites species in the 60 mattress' owners, whom had previously been diagnosed with respiratory allergy. RESULTS: The Pyroglyphidae family was found in 100% of dust samples. Dermatophagoides pteronyssinus (Dp) and Dermatophagoides farinae (Df) were the species most frequently found (>90%). These findings were in agreement with the skin tests results, where 100% of patients were positive to Dp, whereas 70% was positive to Df. It was evidenced for the first time the presence of Blomia tropicalis in Tamaulipas, Veracruz and Campeche states, and Dermatophagoides siboney in Campeche. Both species are important allergenic sources in tropical/subtropical climates. CONCLUSIONS: These results confirm the importance of Pyroglyphid house dust mites, as indoor sensitizers in different climatic and geographical regions in México, as well as, the relevance of tropical species, particularly Blomia tropicalis and D. Siboney, in certain areas.

The indoor level of house dust mite allergen is associated with severity of atopic dermatitis in children.

We attempted to investigate the correlation between the severity of atopic dermatitis (AD) in children and the indoor level of house dust mite (HDM) allergens. Ninety-five patients (31.1 ± 19.5 months of age) with AD were enrolled in this study, and serum specific IgE against Dermatophagoides pteronyssinus and D. farinae was measured. The severity of AD was assessed using the visual analogue scale on the same day of house dust collection. Living rooms and mattresses where the child usually slept were vacuumed for 2 minutes and concentrations of Der f 1 were measured by enzyme-linked immunosorbent assay. The skin symptoms were more severe in patients with Der f 1 concentrations in living room > 2 µg/g dust than ≤ 2 µg/g dust (P = 0.018). This difference was noted in AD patients without sensitization to HDM (P = 0.004), but not in patients with sensitization. There was no difference in symptom severity according to Der f 1 concentrations in mattresses (P = 0.062). The severity of skin symptoms is associated with indoor concentrations of HDM in children with AD, and it is likely to act as nonspecific irritants as well as allergens in AD skin lesions.

[Mites in mattress dust and relevant environmental factors in student dormitories in Shenzhen].

Three hundred and eight mattress dust samples were collected from college dormitories in Shenzhen with a mite prevalence of 88% (271/308). From the samples, 6163 mites were isolated and identified. Dermatophagoides farinae, D. pteronyssinus and Blomia tropicalis were three most abundant species, occupying 29.7%, 21.7% and 17.9%, respectively. It was found that sex of the students, mattress cover (bamboo mat or bed sheet), with or without air conditioner installation, and daily using of air conditioner (<2 h, 2-8 h and >8 h) had no significant influence on the mite prevalence (P>0.05). However, logistic regression analysis revealed that the risk of mite sensitization in male student dormitory was significantly lower than that in female dormitory (OR=0.55, P=0.038), and the risk of using bed sheets was significantly higher than using bamboo mats (OR=2.13, P=0.040). Both mite prevalence and the risk of mite sensitization significantly decreased with higher floor of the dormitory building.

Dust mite species and allergen concentrations in beds of individuals belonging to different urban socioeconomic groups in Brazil.

BACKGROUND: Dermatophagoides pteronyssinus, Dermatophagoides farinae and Blomia tropicalis dust mites are among the most important agents of hypersensitivity reactions in human beings. However, a role of other mites in the etiology of these reactions has not yet been excluded. OBJECTIVES: To investigate the nature of the dust mite fauna and the presence of Der p 1 (allergen 1 of Dermatophagoides pteronyssinus) and Blo t 5 (allergen 5 of Blomia tropicalis) on beds used by individuals with different socioeconomic backgrounds in Salvador, a major Brazilian city and to investigate possible associations of mite frequencies and allergen levels with (a) season of the year, (b) housing characteristics, (c) bed cleaning behaviors that could affect mite densities, and (d) allergy history. METHODS: Dust samples were collected from 459 beds of 101 residences from two groups with different socioeconomic levels (hereafter called wealthy and poor groups) in the city of Salvador, Brazil, for the identification of mite species and determination of Der p 1 and Blo t 5 levels. History of allergy was collected using the ISAAC phase I questionnaire. RESULTS: Eighty nine percent of the beds analyzed harbored at least one mite species. B. tropicalis was found in 71.8%, D. pteronyssinus in 39.9%, Cheyletus sp. in 33.9%, and Gohieria fusca in 21.1% of the beds. B. tropicalis was found with a similar frequency in beds of the two socioeconomic groups; D. pteronyssinus was found more frequently in the beds of the wealthy than of the poor group, whereas the reverse was observed with G. fusca. The concentrations of Der p 1 and Blo t 5 allergens exceeded the cut-off for sensitization of 2 microg/g of dust in 94.0% and 69.3% of the wealthy and poor group beds, respectively. No associations were found between history of allergy and mite species or between history of allergy and the concentrations of mite allergens. CONCLUSIONS: The observation of B. tropicalis and D. pteronyssinus as the most frequently found mites is consistent with previous reports from tropical regions. The higher frequency of G. fusca in beds of individuals from the poor group than those from the wealthy group could be a consequence of different bed cleaning behaviors between the two groups.

Combined pyrethroid and carbamate 'two-in-one' treated mosquito nets: field efficacy against pyrethroid-resistant Anopheles gambiae and Culex quinquefasciatus.

A new approach is proposed in the treatment of mosquito nets, using a 'two-in-one' combination of pyrethroid and non-pyrethroid insecticides applied to different parts of bednets. The objectives are mainly to overcome certain limitations of pyrethroid-impregnated bednets currently recommended for malaria control purposes. Apart from developing alternatives to pyrethroid dependency, we sought to counteract pyrethroid irritant effects on mosquitoes (excito-repellency) and resistance to pyrethroids. The idea takes advantage of the presumed host-seeking behaviour of mosquitoes confronted by a net draped over a bed, whereby the mosquito may explore the net from the top downwards. Thus, nets could be more effective if treated on the upper part with residual non-irritant insecticide (carbamate or organophosphate) and with a pyrethroid on the lower part. Sequential exposure to different insecticides with distinct modes of action is equivalent to the use of a mixture as a potential method of managing insecticide resistance. We also intended to improve the control of nuisance mosquitoes, especially Culex quinquefasciatus Say (Diptera: Culicidae) that often survive pyrethroids, in order to encourage public compliance with use of insecticide-treated nets (ITNs). Polyester bednets were pretreated with residual pyrethroid (bifenthrin 50 mg/m2 or deltamethrin 25 mg/m2) on the lower half and with carbamate (carbosulfan 300 mg/m2) on the upper half to minimize contact with net users. Unreplicated examples of these 'two-in-one' treated nets were field-tested against wild mosquitoes, in comparison with an untreated net and bednets treated with each insecticide alone, including PermaNet wash-resistant formulation of deltamethrin 50 mg/m2. Overnight tests involved volunteers sleeping under the experimental bednets in verandah-trap huts at Yaokofikro, near Bouaké in C te d'Ivoire, where the main malaria vector Anopheles gambiae Giles, as well as Culex quinquefasciatus Say, are highly resistant to pyrethroids. Efficacy of these ITNs was assessed in the huts by four entomological criteria: deterrency and induced exophily (effects on hut entry and exit), blood-feeding and mortality rates (immediate and delayed). Overall, the best impact was achieved by the bednet treated with carbosulfan alone, followed by 'two-in-one' treatments with carbosulfan plus pyrethroid. Blood-feeding rates were 13% An. gambiae and 17% Cx. quinquefasciatus in huts with untreated nets, but only 3% with carbosulfan ITNs, 7-11% with combined ITN treatment, 6-8% An. gambiae and 12-14% Cx. quinquefasciatus with pyrethroid alone. Mosquitoes that entered the huts were killed sooner by nets with combined treatment than by pyrethroid alone. Mortality-rates in response to ITNs with carbosulfan (alone or combined with pyrethroid) were significantly greater for Cx. quinquefasciatus, but not for An. gambiae, compared to ITNs with only pyrethroid. About 20% of sleepers reported potential side-effects (headache and/or sneezing) from use of ITN treated with carbosulfan alone. Further development of this new 'two-in-one' ITN concept requires a range of investigations (choice of effective products, cost-benefit analysis, safety, etc.) leading to factory production of wash-resistant insecticidal nets treated with complementary insecticides.

Quantification of pyrethroid insecticides from treated bednets using a mosquito recombinant glutathione S-transferase.

Recombinant glutathione S-transferase (agGST1-6) from the malaria vector mosquito Anopheles gambiae Giles (Diptera: Culicidae) was expressed in Escherichia coli using a pET3a vector system. The expressed enzyme was biochemically active with reduced glutathione (GSH) and 1-chloro-2,4-dinitrobenzene (CDNB). Activity of agGST1-6 with GSH and CDNB was inhibited to different degrees by both alpha-cyano and non-alpha-cyano pyrethroid insecticides. This inhibition was used to develop an assay for quantification of pyrethroids. Standard curves of insecticide concentration against percentage of enzyme inhibition or volume of iodine solution were established by spectrophotometry and iodine volumetric titration, respectively, for permethrin and deltamethrin. These assays allowed estimation of pyrethroid concentrations both spectrophotometrically and visually. For the residue assay of each insecticide, a cut-off point of 50% of the initial pyrethroid impregnation concentration was used, which should differentiate between biologically active and inactive treated bednets. The cross-reactivity of the primary permethrin photodegradants (3-phenoxyalcohol and 3-phenoxybenzoic acid) with the recombinant agGST1-6 was assayed in the same system. No agGST1-6 inhibition by the insecticide metabolites was observed, suggesting that the system is unaffected by primary permethrin metabolites and will accurately measure insecticide parent compound concentrations. The estimated pyrethroid insecticide concentrations, given spectrophotometrically and by iodine titration assay, were comparable to those obtained by direct HPLC quantification of residues extracted from bednets. Hence, it should be relatively easy to adapt this method to produce a test kit for residue quantification in the field.

Olyset Net efficacy against pyrethroid-resistant Anopheles gambiae and Culex quinquefasciatus after 3 years' field use in C te d'Ivoire.

Pyrethroid-impregnated bednets are advocated for personal protection against malaria vectors. To avoid the need for periodic re-treatment, it would be advantageous to have nets that retain insecticidal efficacy for years and withstand repeated washing. Such a type of commercially produced bednet with permethrin 2% incorporated in polyethylene fibres (trademark Olyset Net supplied by Sumika Life-Tech Co., Osaka, Japan) was evaluated against mosquitoes in veranda-trap huts at Yaokoffikro, near Bouaké, C te d'Ivoire, by standard WHOPES phase II procedures. Four Olyset Nets were compared with a standard untreated polyester net as control. They comprised three examples previously used in a village for over 3 years (one washed, one dirty, one very dirty) and a previously unused Olyset Net, newly unwrapped, from the same original batch. Bioassays with 3 min exposure of susceptible Anopheles gambiae Giles (Diptera: Culicidae) gave >99% mortality of female mosquitoes tested on the 'new' Olyset Net. The used Olyset Nets gave mortality rates averaging 83% for the washed net, 85% for the dirty net and 55% for the very dirty net (within 24-h following 3 min exposure). Thus, Olyset Nets were found to remain remarkably effective against susceptible An. gambiae for at least 3 years under field conditions. Wild pyrethroid-resistant populations of Culex quinquefasciatus Say and An. gambiae (savanna cytotype with 96% kdr) were assessed during June-August 1999 for their responses to sleepers protected by nets in the experimental huts. With regard to hut entry by foraging female mosquitoes, Olyset Nets showed some deterrency against An. gambiae (44% reduction by the new net, approximately 20% by the dirty nets, none by the washed net), but not against Cx. quinquefasciatus. Among mosquitoes entering the hut with untreated control net, 30-34% tried to leave (exophily) but were caught in the verandah trap. The permethrin repellency of Olyset Nets increased exophily by 19% for An. gambiae and 14% for Cx. quinquefasciatus. Blood-feeding rates were 16% An. gambiae and 35% Cx. quinquefasciatus in the hut with sleeper under the untreated net (showing considerable prevention of biting), 22-26% of both species in huts with washed or dirty used Olyset Nets (not significantly different from control), while the biting success rate of Cx. quinquefasciatus (but not kdr An. gambiae) was more than halved by the 'new' Olyset Net. Mortality rates of pyrethroid-resistant An. gambiae and Cx. quinquefasciatus from the huts were, respectively, 3% and 8% with the untreated polyester net, 27.5% and 17% with the 'new' Olyset, 15% and 17.5% with the washed Olyset, 16-25% and 17-20% with dirty old Olyset Nets. Kill differences between nets are significantly different for both An. gambiae and Cx. quinquefasciatus. Unfortunately the washed used Olyset Net showed least activity against resistant mosquitoes, despite its greatest activity against susceptible An. gambiae. In each case there was evidence that a high proportion of mosquitoes failed to feed through the net (many of them dying from starvation when they could not leave the closed hut), with indications that dirty Olyset nets enhanced this protective value.

[Reduction of colonization of new mattresses with bacteria, moulds and house dust mites by complete mattress covers]. / Reduktion der Besiedlung neuwertiger Matratzen mit Bakterien, Schimmelpilzen und Hausstaubmilben durch Matratzenganzbezüge.

BACKGROUND AND OBJECTIVE: We investigated if the colonisation of new mattresses with house dust mites, bacteria, and fungi could be reduced by using synthetic mattress covers as compared to common cotton covers. PATIENTS/METHODS: 84 healthy volunteers were assigned to two groups. Group A (n = 43) received the cotton covers, group B (n = 41) the synthetic covers which were made of a polyester microfaser with a polyurethane surface layer (Pro-Tex, Germed, Schwarzenbek, Germany). RESULTS: The mite antigen concentration after six months was significantly lower in group B. Three months after the start of the study counts of bacteria and moulds were significantly higher in group A compared to group B. CONCLUSIONS: It can be recommended that patients suffering from an allergy to mites or moulds may reduce their domestic allergen exposure by using the synthetic mattress covers tested in this study. Since cotton covers are very likely to become colonised by bacteria and moulds, they must be cleaned periodically (at least every 2nd-3d month).

Mite allergen (Der p 1) levels in houses of children with atopic dermatitis: the relationship with allergometric tests.

Several studies, in particular in adult groups, have evaluated the involvement of mites in the pathogenesis of atopic dermatitis (AD). This still remains controversial. The objective of this study was to determine the level of house dust mites (HDMs) in the beds of a group of children with AD and correlate these levels with their allergometric assessment. Forty-one children with AD underwent allergometric tests (prick test, patch test and radioallergosorbent test, RAST) and the concentration levels of HDMs in their homes were evaluated. Our data show that about half of the children (51%) with AD presented Dermatophagoides pteronyssinus positivity (prick test and/or RAST and/or patch test). Dust was collected in the period October-November from the children's beds, by the same two operators, using a dust-collection device. The dust mite level was tested by an enzyme-linked immunosorbent assay with antibody against Der p 1 allergen. Ten children (24%) presented a Der p 1 concentration > 2 microgram/g of dust (the value assumed to be a risk level for sensitization), 20 (49%) between 0.1 and 2 microgram/g and 11 (27%) < 0.1 microgram/g of dust. In the group with the highest Der p 1 concentration (> 2 microgram/g dust) nine children (90%) presented an allergometric D. pteronyssinus sensitivity, the difference with the other two groups being statistically significant at P < 0.018. The results of the present study show that the highest HDM concentrations were observed in the group with an allergometric D. pteronyssinus positivity (prick test and/or RAST and/or patch test). It is hypothesized that a higher HDM concentration may elicit D. pteronyssinus IgE sensitization and delayed hypersensitivity in children with AD.

[Infestation by Pediculus humanus (Anoplura: Pediculidae) in a metropolitan area of southeast Brazil]. / Infestação por Pediculus humanus (Anoplura: Pediculidae) no Município de São Paulo, SP, Brasil.

Adults, nymphs and nits of the Pediculus humanus were found in a frame-house infesting the clothes and bedding of three inhabitants in a shanty town in S. Paulo county, S. Paulo State. A total of 198 nits were found glued in 15.0 cm2 of fibres of the infested clothing, giving a ratio of 13.2 nits/cm2. Having in view that the precarious living conditions, promiscuity, absence of basic sanitation and negligence of the sanitary authorities in various Brazilian cities, this situation should not be underestimated. This find should be more frequent than an isolated observation.