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Biomedical subjects

G Dreyer

Publications and source records attributed to G Dreyer.

At least 73 records · Page 4Linked to original sources
PubMedDate not supplied

Treatment of bancroftian filariasis in Recife, Brazil: a two-year comparative study of the efficacy of single treatments with ivermectin or diethylcarbamazine.

The effectiveness of single oral doses of ivermectin (200 or 400 micrograms/kg) and diethylcarbamazine (DEC, 6 mg/kg), preceded 4 d earlier by either placebo or very small doses of these drugs, was compared, over a 2-year period, in a double-blind trial in 67 microfilaraemic Brazilian men with bancroftian filariasis. Regimens containing ivermectin alone decreased the number of microfilariae significantly faster and more effectively for the first month after treatment than regimens containing DEC alone, but the latter were significantly more effective throughout the second year after treatment (1.7-8.2% of pretreatment levels with DEC vs. 12.6-30.8% with ivermectin during that period); the higher ivermectin dose showed a tendency towards more effectiveness than the lower dose. Most effective was the combination of ivermectin (20 micrograms/kg) followed 4 d later by DEC (6 mg/kg), with reduction of microfilaraemia to 2.4% of pretreatment levels at 2 years. Adverse reactions were well tolerated with all regimens, the reactions being significantly more generalized (i.e., fever) following ivermectin and localized (i.e., scrotal inflammatory nodules around dying adult worms) following DEC. Further trials of single-dose combination therapy vs. single high doses of ivermectin or DEC should determine the ideal regimen for treatment and control of bancroftian filariasis.

Administration, Oral↗
PubMedDate not supplied

Evaluation of PCR-based methods for the diagnosis of infection in bancroftian filariasis.

The value of the polymerase chain reaction (PCR) in the diagnosis of Wuchereria bancrofti infection was evaluated in comparison to microscopical examination of night blood smears, Nuclepore filtration, serology and ultrasonography. No correlation was found between PCR-based deoxyribonucleic acid (DNA) probing and serology. We did not find any evidence of free filarial DNA in either blood plasma or chylocoele fluid. We conclude that the 2 PCR-based techniques evaluated are not more sensitive than Nuclepore filtration for detection of W. bancrofti microfilaraemia, need at least 1 intact microfilaria in the volume of blood used for DNA extraction, and were much inferior to ultrasonography for detection of amicrofilaraemic adult worm carriers.

DNA, Helminth↗
PubMedDate not supplied

Histological evidence for adulticidal effect of low doses of diethylcarbamazine in bancroftian filariasis.

The ability of diethylcarbamazine (DEC) to kill adult Wuchereria bancrofti worms was evaluated by examining lymphatic nodules formed after treatment with 4 different treatment schedules of 193 males living in the endemic area of Greater Recife, Brazil. Lymphatic nodules appeared in the spermatic cord or upper extremities in 43 of 138 microfilaraemic individuals, in 3 of 30 amicrofilaraemic patients with filarial disease manifestations, and in 1 of 25 asymptomatic amicrofilaraemic residents of the endemic area treated with DEC. Fourteen of these nodules were surgically removed 10-150 d after the start of treatment. Regardless of the DEC dosage and schedule used, all nodules contained damaged and degenerating adult worms. An exuberant granulomatous process with large numbers of eosinophils and progressive fibrosis gradually developed around the dead parasites. The mechanism(s) by which DEC killed adult W. bancrofti could not be determined.

Adolescent↗
PubMedDate not supplied

Amicrofilaraemic carriers of adult Wuchereria bancrofti.

To determine the extent to which Wuchereria bancrofti infections can be detected in asymptomatic amicrofilaraemic men in Greater Recife, Brazil, we studied 100 asymptomatic men who were long-term residents (> or = 15 years) of this filariasis-endemic area and who were amicrofilaraemic in 60 microL of capillary blood collected at night. Increasing amounts (1, 5, and 10 mL) of venous blood were collected in consecutive weeks, filtered, and examined for microfilariae; 27 men were eventually found to be microfilariaemic and 10 remained amicrofilaraemic but were found to be carriers of living adult W. bancrofti by ultrasound examination of the scrotal area. Thus, 37% of 'amicrofilaraemic' men (in 60 microL of blood) were found to be infected by more thorough investigation. Ultrasound is a valuable tool to identify adult worm infections in amicrofilaraemic persons, particularly for evaluation of serological assays and immunological studies in which the distinction between 'amicrofilaraemic adult worm carriers' and 'endemic normal subjects' is critical.

Adolescent↗
PubMedDate not supplied

Occurrence of living adult Wuchereria bancrofti in the scrotal area of men with microfilaraemia.

To determine the frequency with which living adult Wuchereria bancrofti can be detected by ultrasound in the scrotal area of men with filarial infection, we used a 7.5 MHz transducer to perform weekly ultrasound examinations on 100 microfilaraemic men (18-34 years old) from Greater Recife, Brazil. The peculiar pattern of movement that characterizes the adult worm image on ultrasound (the filaria dance sign) was detected in the lymphatic vessels of the spermatic cord in 80 men (bilaterally in 29 men). Among 20 men with no filaria dance sign, the geometric mean microfilarial density was 68/mL, compared with 238/mL and 775/mL among those with unilateral and bilateral filaria dance signs, respectively (P = 0.0001). The lymphatic vessels of the spermatic cord appear to be a common, and perhaps the principal, site of adult W. bancrofti in men with asymptomatic microfilaraemia. Studies are needed to define the relationship between the presence of filarial worms in the scrotal area and the development of filaria-associated morbidity.

Adolescent↗
PubMedDate not supplied

Assessment of the efficacy of diethylcarbamazine on adult Wuchereria bancrofti in vivo.

To assess directly the effect of various doses of diethylcarbamazine (DEC) on adult Wuchereria bancrofti, 31 infected men were randomly assigned to receive an initial single DEC dose of 1 mg/kg (n = 7), 6 mg/kg (n = 10), or 12 mg/kg (n = 14). Beginning 7 d later, the dosage of DEC and duration of treatment were progressively increased for 7-10 weeks. Physical examinations were performed to detect scrotal nodules and the scrotal area was examined by ultrasound (7.5 MHz transducer) to monitor the 'filaria dance sign' (FDS), the characteristic pattern of adult worm movement. Of 53 adult worm 'nests' that were detected by ultrasound, 22 (41.5%) were DEC-sensitive (FDS became non-detectable and a nodule became palpable at the site); 20 (37.7%) were not sensitive (FDS remained unchanged and detectable and no nodule developed), and 11 (20.8%) showed mixed responses (FDS remained detectable but a palpable nodule developed). All but one sensitive or mixed response occurred within 1 week after the initial single dose. Of 39 'nests' in men who initially received a single 6 or 12 mg/kg dose of DEC, 20 (51.3%) had sensitive responses compared to 2 (14.3%) of 14 'nests' in men who received a single 1 mg/kg dose (P = 0.04). Above 6 mg/kg, the macrofilaricidal effect of DEC did not increase with dose; a significant proportion of adult W. bancrofti were not susceptible to DEC during the study period.

Adult↗
PubMedDate not supplied

Direct assessment in vivo of the efficacy of combined single-dose ivermectin and diethylcarbamazine against adult Wuchereria bancrofti.

When ivermectin and diethylcarbamazine (DEC) are given simultaneously in a single dose to persons with Wuchereria bancrofti infection, the resulting suppression of microfilaraemia is more profound and sustained than when either drug is given alone. To assess whether this effect is a result of enhanced macrofilaricidal efficacy, we used ultrasound to monitor the adult worms in the scrotal area of men with W. bancrofti microfilaraemia. Twenty-one men were treated simultaneously with DEC (6 mg/kg) and either 200 micrograms/kg or 400 micrograms/kg of ivermectin (11 and 10 men, respectively). Ten other men received a single 200 micrograms/kg dose of ivermectin followed 5 d later by a 6 mg/kg dose of DEC (sequential treatment). All men became amicrofilaraemic after treatment and all except one remained so for one year. Cessation of adult worm movement, indicative of death of all the adult worms in a given 'nest', was observed in none of 30 nests in men who received simultaneous treatment and in 3 of the 19 nests (16%) in the men who received sequential treatment (P = 0.05). Scrotal nodules were detected in 5 of 21 men (24%) who received simultaneous treatment and in 8 men (80%) who received sequential treatment (P < 0.01). Thus, co-administration of ivermectin with DEC seems to interfere with the macrofilaricidal action of DEC. These findings have implications both for treatment of the individual patient and for community-based drug distribution programmes designed to interrupt transmission of W. bancrofti.

Adolescent↗
PubMedDate not supplied

Abnormalities of the leg lymphatics are not specific for bancroftian filariasis.

Studies using conventional angiography or non-invasive scintigraphy have revealed widespread abnormalities in the lymphatics of the legs of patients with bancroftian filariasis, regardless of whether clinical lymphoedema is present. To determine if the observed changes were specific for filarial infections, we imaged the lymphatics of both legs in native residents of an area in Brazil where filariasis is not endemic. Study participants were matched by age, socioeconomic status and physical activities to patients with filariasis in Recife, evaluated in parallel. Based on textbook criteria, only one of 15 study participants had a completely normal lymphoscintigram. Modest to severe pathology of the leg lymphatics was observed in the remaining 14 residents of the non-endemic area and in 49 of 50 patients with bancroftian filariasis. These results indicated that factors other than filarial worms are a common cause of subclinical pathology of the leg lymphatics in north-eastern Brazil, and that the latter is not specific for bancroftian filariasis.

Brazil↗
PubMedDate not supplied

Bancroftian filariasis in a paediatric population: an ultrasonographic study.

Little is known about lymphatic filariasis or the anatomical location of adult Wuchereria bancrofti in children. Seventy-eight children from Greater Recife, 23 microfilaria-positive and 55 microfilaria-negative in approximately 60 microL blood, underwent ultrasound examinations of the major superficial lymphatic vessels of the limbs, scrotal area (boys), and breast area (girls). The characteristic movements of adult worms, known as the filaria dance sign (FDS), were detected in 11 (14.1%) children. In 9 boys, the FDS was detected in lymphatic vessels of the scrotal area (8, ages 14-16) and the inguinal cord (1, age 11). In girls, the FDS was detected in a crural lymphatic vessel and an axillary lymph node. FDS detection was more common in boys (P = 0.06), older children (P = 0.001), and children with microfilaraemia (P = 0.05). Diffuse lymphangiectasia was visualized in 4 boys (ages 14-16) and 2 children had clinical signs of filariasis. These ultrasonographic findings associate W. bancrofti with both infection and disease in children.

Adolescent↗
PubMedDate not supplied

Acute attacks in the extremities of persons living in an area endemic for bancroftian filariasis: differentiation of two syndromes.

The natural history of lymphatic disease in human filariasis remains unclear, but recurrent episodes of acute lymphangitis are believed to constitute a major risk factor for the development of chronic lymphoedema and elephantiasis. Prospective analysis of 600 patients referred to the filariasis clinic of the Centro de Pesquisas Aggeu Magalhães/FIOCRUZ in Recife, Brazil, indicated that 2 distinct acute syndromes accompanied by lymphangitis occur in residents of this filariasis-endemic area. One syndrome, which we call acute filarial lymphangitis (AFL), is caused by the death of adult worms. It is relatively uncommon in untreated persons, usually is asymptomatic or has a mild clinical course, and rarely causes residual lymphoedema. The second syndrome, of acute dermatolymphangioadenitis (ADLA), is not caused by filarial worms per se, but probably results from secondary bacterial infections. ADLA is a common cause of chronic lymphoedema and elephantiasis in Recife as well as in other areas of Brazil where lymphatic filariasis is not present. The syndromes of AFL and ADLA can be readily distinguished from each other by simple clinical criteria.

Acute Disease↗
PubMedDate not supplied

Urine cytology as a screening test for bladder infiltration in cervical cancer.

Ultrasound is currently used as a screening test for bladder infiltration in patients with advanced-stage cervical cancer at our institution. Cystoscopy is reserved for patients with abnormal bladder ultrasound findings. This study was undertaken to reevaluate this policy and to compare the results of different screening tests. The study was carried out in Pretoria academic complex. All newly diagnosed cervical carcinoma patients stage II and above were included in this study. The standard staging investigations were done on all patients. In addition, urine midstream and catheter specimens were sent for cytology. Cystoscopy and biopsy were performed on all patients. Two hundred twenty-eight patients were enrolled into this study. At cystoscopy, 47 patients had bladder mucosa suspicious of malignant infiltration, of which 17 had bladder mucosa infiltration diagnosed on histology. Urine catheter cytology has a sensitivity of 94% and specificity of 82% for bladder mucosa infiltration. The predictive value of a positive test is 31% and for a negative test is 99%. Catheter urine cytology is a very useful screening test for bladder infiltration in patients with cervical cancer. Cystoscopy should be reserved for patients with abnormal urine cytology in resource-poor settings with a large burden of disease.

Biopsy↗
PubMedDate not supplied

Human pulmonary dirofilariasis: a review.

The authors presented a detailed summary of the geographical distribution, clinical and pathological aspects of human pulmonary dirofilariasis. Although benign, this zoonosis, of which Dirofilaria immitis is the major etiological agent, represents a medical problem since it produces symptoms which may be confused with neoplasia and thus may subject patients to unnecessary thoracic surgery. Of 229 cases cited in the literature, only 17 were reported in Brazil, despite the existence of highly favorable conditions for the transmission of this infection in man. Thus it may well be that this parasitic infection remains underdiagnosed. Finally, the importance of a differential diagnosis between dirofilariasis and pulmonary neoplasia is emphasized in cases where there is a solitary subpleural nodule ("coin lesion") present. In addition, the development and improvement of modern immunological diagnostic techniques are essential to distinguish this benign disease from other pathological conditions and thus avoid unnecessary surgery. These techniques may reveal the true prevalence of this parasitic infection in our environment.

Animals↗
PubMedDate not supplied

[History of lymphatic filariasis in Pernambuco. I. Epidemiologic and control aspects].

This paper is a review of lymphatic bancroftian filariasis in the State of Pernambuco. Brazil. It shows that reports have existed since the 1st decade of the century. Knowledge of the disease in several areas during different periods makes a retrospective analyses very interesting, particularly in Great Recife. It is in the city that the epidemiological and control aspects of the diseases are examinations in details.

Animals↗
PubMedDate not supplied

[Diethylcarbamazine in the treatment of Bancroft's filariasis].

The authors presented a detailed review about the treatment of bancroftian filariasis with diethylcarbamazine. The interesting aspects about the drug discovery and the basic concepts about its pharmacology were reported in a summarised form. On the other hand, emphasis was made about the speculation done by several authors about the intriguing findings regarding its efficacy reported in the literature. Latter, it was brought the new advances about the disease, as for example, the visualization by ultrasound of living Wuchereria bancrofti adult worm on its natural host--the human being. This made possible the comprehension of several paradoxical issues reported, focusing the treatment of infection using diethylcarbamazine. So far, because of the lack of ideal drug with micro and macrofilaricidal properties, together with the new understand about the disease and the new parameters for monitoring the efficacy of the drug, diethylcarbamazine has back its importance conquered at the begin of its discovery, almost fifth years ago.

Animals↗
PubMedDate not supplied

[Rational for morbidity management in bancroftian filariasis endemic areas].

Selection of the most appropriate therapy for the patient with bancroftian filariasis requires a knowledge of the diverse clinical characteristics of filarial disease and their pathogenesis. As a result of new diagnostic tests and clinical advances, our understanding of bancroftian filariasis has changed rapidly, as have our ideas about treatment. In the past, it was believed that elephantiasis was caused by an immunologic reaction of the host to the filarial parasite. From this perspective, elephantiasis was seen as the endpoint of an unalterable relationship between the host and the parasite, and given the absence of effective medication or procedures, affected individuals were considered "immunologically predisposed" to this end-stage disease. In the last few years, however, new evidence has suggested that lymphedema and elephantiasis have another etiologic agent. Namely, the principal factor in the evolution of lymphedema and elephantiasis is the involvement of recurrent secondary bacterial infections. Today, it is clear that other forms of supportive therapy (including education and psychological counseling) are necessary and are often more important than antiparasitic drugs.

Animals↗