RESUMEN
Women with usual ductal hyperplasia have a relative risk of 1.6-1.9 of subsequent breast cancer development. This slightly increased risk is generally not considered sufficiently high to justify (chemo)preventive therapy. It is therefore important to identify high-risk ductal hyperplastic lesions that would benefit from such a treatment. Nuclear morphometric features have been shown in previous work to be useful for objectively describing morphologic features associated with high risk in (pre)invasive breast lesions. The aim of this study was to evaluate whether such morphometric features can also predict subsequent invasive cancer development in patients with the common pattern of usual ductal hyperplasia or a normal breast biopsy. The present case-control study included 423 women with normal breast biopsies (n = 89) or biopsies containing usual ductal hyperplasia (n = 334). Of these 423 women, 132 developed invasive breast cancer during follow-up (mean 16.7 +/- 7.0 years). On the original hematoxylin and eosin-stained sections, nuclear morphometry was performed with a digitizing video overlay system, and mitotic and apoptotic indices were assessed. Patients with mean nuclear feature values for area, perimeter, diameter or longest axis above the 75th percentile had 1.6-1.7 times the breast cancer risk of women with mean nuclear feature values below this value. Pairwise combinations of these features yielded slightly higher cancer risks for the fourth quartile patients, with the highest risk (1.9) for patients with SD of nuclear area and perimeter values above the 75th percentile. The number of apoptotic or mitotic cells had no prognostic value for patients with apparently normal tissue or usual ductal hyperplasia. Our results give a first indication that normal breast tissue or usual ductal hyperplasia harbor nuclear morphologic changes that, when assessed by morphometry, may be used to predict breast cancer development. It is worthwhile studying this further in independent groups of patients with long-term follow-up.
Asunto(s)
Mama/anatomía & histología , Adolescente , Adulto , Anciano , Apoptosis/fisiología , Biopsia , Mama/citología , Mama/patología , Neoplasias de la Mama/epidemiología , Neoplasias de la Mama/patología , División Celular/fisiología , Femenino , Estudios de Seguimiento , Humanos , Hiperplasia/patología , Persona de Mediana Edad , Valor Predictivo de las Pruebas , PronósticoRESUMEN
There is increasing evidence that there are different progression routes leading to invasive breast cancer, depending on histology and differentiation grade. The aim of this study was to determine alterations in the expression of proteins involved in proliferation and apoptosis in non-invasive and invasive ductal breast lesions. Immunohistochemistry was performed on 106 usual ductal hyperplasias (UDH), 61 DCIS lesions and 53 invasive ductal breast carcinomas. Increased proliferation (Ki67), overexpression of cyclin D1, HER-2/neu, p21 and p53, and decreased expression of bcl-2 and p27 could already be found in UDH. Significant differences between UDH and DCIS lesions were found for only one protein when UDH was compared with well-differentiated DCIS (p27), for three proteins when compared with intermediately differentiated DCIS (p21, cyclin D1, Ki-67), and for all proteins when compared with poorly-differentiated DCIS. Comparing DCIS with invasive lesions of same differentiation grade, proliferation was elevated in the invasive lesions. Altered expression of the other proteins was in general only slightly increased in the invasive lesion compared with DCIS. The number of proteins with altered expression per lesion was highest in poorly-differentiated lesions and was comparable between DCIS and invasive cancer of the same differentiation grade. In conclusion, the biggest changes in expression of these proliferation and apoptosis related proteins appear to occur during the transition from hyperplasia to DCIS; they probably play a minor role in the transition from DCIS to invasive breast lesion of same differentiation grade. Well-differentiated in situ and invasive breast lesions share many of the aberrations in expression of these proteins, as do poorly-differentiated in situ and invasive lesions. However, there are many differences between the well and poorly-differentiated lesions. This further supports the existence of different progression routes leading to breast cancer.
Asunto(s)
Neoplasias de la Mama/metabolismo , Carcinoma in Situ/metabolismo , Carcinoma Ductal de Mama/metabolismo , Proteínas de Ciclo Celular/metabolismo , Apoptosis , Neoplasias de la Mama/patología , Carcinoma in Situ/patología , Carcinoma Ductal de Mama/patología , Ciclina D1/análisis , Femenino , Humanos , Inmunohistoquímica , Antígeno Ki-67/análisis , Proteínas Proto-Oncogénicas c-bcl-2/análisis , Receptor ErbB-2/análisis , Proteína p53 Supresora de Tumor/análisisRESUMEN
Ductal invasive grade (G) 2 and G3 carcinomas represent the majority of invasive breast cancers. Previous morphological and cytogenetic studies have provided evidence that ductal invasive G2 carcinoma may originate from at least two different genetic pathways. The aim of this study was to evaluate further the heterogeneity of G2 breast cancer in comparison with G3 cancers by cytogenetic and quantitative analysis. To this end, 35 cases of ductal invasive G2 and 42 cases of ductal invasive G3 carcinomas were investigated by means of comparative genomic hybridization (CGH) and these findings were correlated with DNA ploidy status, mitotic activity index (MAI), mean nuclear area (MNA), volume per lumen (VPL), and clinico-pathological parameters. The findings of this study demonstrate that ductal invasive G2 carcinomas, in contrast to ductal invasive G3 carcinomas, have to be interpreted as the morphological end stage resulting from two different cytogenetic and morphological pathways; the loss of 16q material is the cytogenetic key event in the evolution of a subgroup of this entity. By correlating genetic alterations with DNA ploidy status, an extended morphology-based cytogenetic progression model is presented, with early and late genetic alterations in the pathogenesis of breast cancer. The correlation with MAI gives rise to the hypothesis that these different genetic pathways significantly differ in their proliferation rate. Further studies will be required to elucidate which genes contribute to an altered proliferation rate in these subgroups and to the associated prognosis.
Asunto(s)
Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Carcinoma Ductal de Mama/genética , Carcinoma Ductal de Mama/patología , Aberraciones Cromosómicas/genética , Aberraciones Cromosómicas/patología , Modelos Genéticos , Trastornos de los Cromosomas , Cromosomas Humanos Par 1 , Cromosomas Humanos Par 11 , Cromosomas Humanos Par 13 , Cromosomas Humanos Par 16 , Cromosomas Humanos Par 17 , Cromosomas Humanos Par 20 , Cromosomas Humanos Par 8 , Progresión de la Enfermedad , Femenino , Amplificación de Genes , Eliminación de Gen , Marcadores Genéticos , Humanos , Índice Mitótico , Hibridación de Ácido Nucleico/métodos , Ploidias , Estadísticas no ParamétricasRESUMEN
The aim of this study was to make a thorough inventory of the histologic features of epithelium and stroma within and adjacent to breast fibroadenomas in 396 cases. Breast fibroadenomas seemed to display a wide spectrum of proliferative and nonproliferative histologic changes. Hyperplasia (excluding mild hyperplasia) within the fibroadenoma was found in 32.3% of cases. Carcinoma in situ (CIS; 5 ductal, 3 lobular) was found in 8 fibroadenomas (2.0%) removed from 6 patients, the youngest of whom was 40 years of age. In 3 cases CIS was not confined to the fibroadenoma, but also involved the adjacent parenchyma. No invasive carcinoma was present within this series. Complex histologic features were seen in 40.4% of cases, mostly in relatively older patients (mean age, 35.4 years). Hyperplasia in adjacent tissue was found in 8.8% of cases, usually in older patients (mean age, 45.5 years). Known risk-elevating lesions in and around breast fibroadenomas occur frequently and mostly in patients older than 35 years. These findings may have consequences for the clinical management of a subgroup of patients with fibroadenoma.
Asunto(s)
Neoplasias de la Mama/patología , Fibroadenoma/patología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma in Situ/patología , Carcinoma Intraductal no Infiltrante/patología , Carcinoma Lobular/patología , Niño , Femenino , Humanos , Hiperplasia/patología , Persona de Mediana Edad , Neoplasias Primarias Múltiples/patologíaRESUMEN
BACKGROUND: Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that regulates gene expression in critical pathways involved in tumor growth and metastases. In this report, we investigated whether the level of HIF-1 alpha is increased during carcinogenesis in breast tissue and is associated with other tumor biomarkers. METHODS: Paraffin-embedded clinical specimens from five pathologic stages of breast tumorigenesis and from normal breast tissue were used. HIF-1 alpha protein and the biomarkers vascular endothelial growth factor (VEGF), HER-2/neu, p53, Ki-67, and estrogen receptor (ER) were identified immunohistochemically, and microvessel density (a measure of angiogenesis) was determined. Associations among levels of HIF-1 alpha and these biomarkers were tested statistically. All statistical tests are two-sided. RESULTS: The frequency of HIF-1 alpha-positive cells in a specimen increased with the specimen's pathologic stage (P<.001, chi(2) test for trend) as follows: normal breast tissue (0 specimens with > or = 1% HIF-1 alpha-positive cells in 10 specimens tested), ductal hyperplastic lesions (0 in 10), well-differentiated ductal carcinomas in situ (DCIS) (11 in 20), well-differentiated invasive breast cancers (12 in 20), poorly differentiated DCIS (17 in 20), and poorly differentiated invasive carcinomas (20 in 20). Increased levels of HIF-1 alpha were statistically significantly associated with high proliferation and increased expression of VEGF and ER proteins. In DCIS lesions, increased levels of HIF-1 alpha were statistically significantly associated with increased microvessel density. HIF-1alpha showed a borderline association with HER-2/neu but no association with p53. CONCLUSIONS: The level of HIF-1 alpha increases as the pathologic stage increases and is higher in poorly differentiated lesions than in the corresponding type of well-differentiated lesions. Increased levels of HIF-1 alpha are associated with increased proliferation and increased expression of ER and VEGF. Thus, increased levels of HIF-1 alpha are potentially associated with more aggressive tumors.
Asunto(s)
Biomarcadores de Tumor/metabolismo , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Proteínas de Unión al ADN/metabolismo , Proteínas Nucleares/metabolismo , Factores de Transcripción/metabolismo , Neoplasias de la Mama/irrigación sanguínea , Carcinoma Ductal de Mama/metabolismo , Carcinoma Ductal de Mama/patología , Carcinoma Intraductal no Infiltrante/metabolismo , Carcinoma Intraductal no Infiltrante/patología , Progresión de la Enfermedad , Factores de Crecimiento Endotelial/metabolismo , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Factor 1 Inducible por Hipoxia , Subunidad alfa del Factor 1 Inducible por Hipoxia , Inmunohistoquímica , Antígeno Ki-67/metabolismo , Linfocinas/metabolismo , Receptor ErbB-2/metabolismo , Receptores de Estrógenos/metabolismo , Proteína p53 Supresora de Tumor/metabolismo , Factor A de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial VascularRESUMEN
Breast cancer is thought to originate through progressively aberrant precursor lesions, paralleled by increasing morphological changes. The aim of this study was to quantify nuclear features by image cytometry in invasive breast cancer and its early (hyperplasia) and late (ductal carcinoma in situ) precursor lesions, in order to objectively describe nuclear changes in the spectrum of proliferative intraductal and invasive breast lesions. Image cytometry was performed on tissue sections of 20 samples of normal breast tissue, 71 of usual ductal hyperplasia (UDH), nine of atypical ductal hyperplasia (ADH), and 11 of well-differentiated and 13 of poorly differentiated ductal carcinoma in situ (DCIS) lesions. The invasive breast carcinomas consisted of 19 well-differentiated and 24 poorly differentiated lesions. Through the spectrum from normal breast tissue to invasive carcinoma, progressive changes in many nuclear features were measured. Significant differences were found between nuclei of florid ductal hyperplasia compared with mild and moderate ductal hyperplastic lesions, suggesting that florid ductal hyperplasia may be a more advanced lesion than assumed and may contain cancer precursor cells. No differences were found between ADH and well-differentiated DCIS, suggesting that these lesions are closely related. Feature values of well-differentiated DCIS were comparable to values found in well-differentiated invasive carcinoma and the same applied to poorly differentiated DCIS and invasive lesions. These results support the hypothesis that breast cancer develops through different routes of progression, one leading to well-differentiated invasive cancer through well-differentiated DCIS, and one leading to poorly differentiated invasive cancer through poorly differentiated DCIS. In conclusion, image cytometry reveals progressive changes in nuclear morphological and subvisual chromatin distribution features in the spectrum from intraductal proliferations to invasive breast cancer. This provides evidence for a progression from usual to atypical ductal hyperplasia and then to invasive cancer, through different routes for well-differentiated and poorly differentiated lesions.
Asunto(s)
Neoplasias de la Mama/ultraestructura , Núcleo Celular/patología , Transformación Celular Neoplásica/ultraestructura , Lesiones Precancerosas/ultraestructura , Mama/patología , Carcinoma in Situ/ultraestructura , Carcinoma Ductal de Mama/ultraestructura , Diferenciación Celular , ADN de Neoplasias/análisis , Progresión de la Enfermedad , Femenino , Humanos , Hiperplasia , Citometría de Imagen , Cariometría/métodos , Invasividad NeoplásicaRESUMEN
Classification of preinvasive breast disease could be better founded using biologic markers, thereby increasing reproducibility. We studied 57 breast ductal and lobular in situ carcinomas by means of comparative genomic hybridization and correlated these findings with quantitative features such as the mean nuclear area, mitotic index (MI), apoptotic index (AI), and the presence or absence of necrosis. Loss of 8p and gains of 8q and 6q were associated, respectively, with a significantly higher MI and AI, whereas loss of 16q was associated with a lower MI and AI. A significantly higher number of alterations per case were seen in tumors with gains of 6q, 8q, and 17q and tumors with loss of 13q. Loss of 16q and gain of 17q correlated with the absence or presence of necrosis, respectively. Our data clearly demonstrate that distinct cytogenetic changes correlate with phenotypic changes, proliferation, and apoptosis. These data may be used to refine existing classification schemes.
Asunto(s)
Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Aberraciones Cromosómicas , Apoptosis , Neoplasias de la Mama/clasificación , Carcinoma in Situ/clasificación , Carcinoma in Situ/genética , Carcinoma in Situ/patología , Carcinoma Ductal de Mama/clasificación , Carcinoma Ductal de Mama/genética , Carcinoma Ductal de Mama/patología , Carcinoma Lobular/clasificación , Carcinoma Lobular/genética , Carcinoma Lobular/patología , Humanos , Índice Mitótico , Hibridación de Ácido NucleicoRESUMEN
In several tissues, nuclear differences have been described in normal-appearing cells from patients with invasive carcinomas compared to cases without invasive carcinoma, a phenomenon known as malignancy-associated changes (MACs). The aim of this study was to determine the presence of malignancy-associated changes in breast tissue. Image cytometry was performed on Feulgen stained tissue sections of patients with usual ductal hyperplasia with (n = 30) or without (n = 41) adjacent invasive breast carcinoma. Nuclear features of normal-appearing cells as well as of usual ductal hyperplastic cells were separately compared between the two groups. Many features of normal-appearing epithelial cells were significantly different between cases with and without invasive cancer. Significant differences were also found by measuring ductal hyperplastic nuclei instead of normal-appearing nuclei. Cases with or without cancer could be distinguished with a classification accuracy of 80% by discriminant analysis using 2 nuclear features derived from ductal hyperplastic cells. In conclusion, image cytometry on breast tissue sections shows that malignancy-associated changes can be found in normal as well as in usual ductal hyperplastic breast cells. This could be clinically relevant for the detection of occult breast cancer, for the prediction of risk in these lesions, and to monitor the effect of chemopreventive agents.
Asunto(s)
Neoplasias de la Mama/patología , Carcinoma Ductal de Mama/patología , Citometría de Imagen , Colorantes de Rosanilina , Mama/ultraestructura , Neoplasias de la Mama/ultraestructura , Carcinoma Ductal de Mama/ultraestructura , Núcleo Celular/ultraestructura , Cromatina/ultraestructura , Colorantes , Análisis Discriminante , HumanosRESUMEN
MUC1 mucin is a high molecular weight transmembrane glycoprotein expressed on the apical cell surface of normal glandular epithelia. In many human adenocarcinomas, this protein is up-regulated and/or underglycosylated, and its expression changes from apical to the entire cell membrane. It is thought that entire cell membrane expression of MUC1 reduces cell-cell and cell-extracellular matrix interactions and therefore may facilitate invasive growth and development of metastases. In this study, we determined immunohistochemically the expression of normal and underglycosylated MUC1 in normal breast tissue (n = 8) and in a spectrum of breast lesions, including usual ductal hyperplasia (n = 23), atypical ductal hyperplasia (n = 7), and ductal carcinoma in situ (DCIS) (n = 22). We used 4 monoclonal antibodies; 115D8 is directed to a glycopeptide, the other 3 to the peptide core of the molecule, of which 139H2 is not affected by the degree of glycosylation of MUC1, whereas SM3 and VU-4-H5 stain only underglycosylated forms. All cases showed apical positivity for 115D8 and 139H2. Entire cell membrane expression of fully (normal) glycosylated MUC1 was mainly found in DCIS lesions. Apical staining of SM3 was found in 38% of normal cases and 60% of the ductal lesions with no difference between the different subgroups. Apical staining of VU-4-H5 was found more often in DCIS (27%) than in normal tissue or ductal hyperplasia (3%). Membrane expression of underglycosylated MUC1 was found only in poorly differentiated DCIS. In conclusion, aberrant expression of MUC1, i.e., on the entire cell membrane and/or underglycosylated forms, can be found in ductal hyperplasia with atypia and especially in DCIS of the breast. This finding implies that these lesions with aberrant expression are at higher risk for developing subsequent invasive breast carcinoma.
Asunto(s)
Neoplasias de la Mama/química , Mama/patología , Carcinoma in Situ/química , Carcinoma Ductal de Mama/química , Mucina-1/análisis , Anticuerpos Monoclonales/inmunología , Mama/química , Femenino , Humanos , Hiperplasia , InmunohistoquímicaRESUMEN
We determined the mitotic and apoptotic index through the spectrum of pre-invasive ductal breast lesions to invasive carcinoma in search of disturbances in the proliferation/cell death balance in breast carcinogenesis. Seventy-two pure pre-invasive ductal breast lesions (without invasive carcinoma) and 103 invasive breast carcinomas were used. The numbers of mitotic and apoptotic cells were microscopically counted in hematoxylin and eosin stained sections (MI and AI, respectively), and the ratio of the values of MI and AI was calculated for each individual case (M/A index). A distinction was made between well differentiated and poorly differentiated breast lesions, based on histological type and nuclear grade, to arrive at two plausible progression models for breast carcinogenesis. For the well differentiated breast lesions, the MI was rather equal for hyperplasias and well differentiated DCIS, but increased 6-fold from DCIS to well differentiated invasive carcinoma. The AI remained in the same range, resulting in a 4-fold increase of the M/A index. For the poorly differentiated breast lesions, a significant increase in MI and AI was found from hyperplasia to poorly differentiated DCIS. From DCIS to poorly differentiated invasive carcinoma, the MI increased significantly and the AI decreased 2-fold (n.s.), resulting in a 2.5-fold significant increase of the M/A index. In conclusion, the net increase of the number of cells in the transition from well differentiated pre-invasive to well differentiated invasive carcinoma is accompanied by an increase of cell proliferation rather than decrease in apoptosis, suggesting that in these lesions, proliferation related mechanisms are most important in carcinogenesis and progression. In contrast, in poorly differentiated breast lesions, decreased apoptosis seems to be also important in carcinogenesis and progression. At present, we are gathering patients with invasive breast cancer who had a previous biopsy with a pre-invasive lesion to obtain further more direct evidence for this hypothesis.
Asunto(s)
Apoptosis , Neoplasias de la Mama/etiología , Carcinoma Intraductal no Infiltrante/etiología , Mitosis , Neoplasias de la Mama/patología , Carcinoma Intraductal no Infiltrante/patología , Progresión de la Enfermedad , Femenino , Humanos , Índice MitóticoRESUMEN
Expression of proliferation- and apoptosis-related proteins was studied by immunohistochemistry in 130 usual ductal hyperplasias of the breast, of which 39 cases (30%) had adjacent invasive cancer. Overexpression of cyclin D1 and Ki-67 was found in 6% and 29% of the cases, respectively. Only two mild ductal hyperplasias were Her-2/neu positive. Overexpression of p21 and reduced expression of p27, both cdk-inhibitors, was seen in 16% and 27% of the lesions, respectively. Reduced expression of bcl-2 was found in 16% of the cases, and p53 accumulation was present in 8%. Expression of six of the seven studied proteins showed no significant difference between mild, moderate, or florid ductal hyperplasias, indicating that there are no important cell biological differences with regard to the studied proteins between the lesions within this morphologically continuous spectrum. In addition, there were no differences between lesions with and without an invasive component. Cyclin D1 positivity was exclusively seen in lesions with 75% or more p27-positive nuclei. No significant correlations were found between other proteins. Twenty-three of 91 lesions (25%) had multiple events, of which five showed altered expressions of three or four proteins. In conclusion, altered protein expression of several proliferation- and apoptosis-related genes that are known to be involved in invasive breast cancer also may be found in usual ductal hyperplastic lesions, including several lesions with multiple events. This implies that usual ductal hyperplastic lesions may be among the earliest lesions within the breast oncogenetic spectrum.
Asunto(s)
Apoptosis , Mama/patología , Proteínas de Ciclo Celular/metabolismo , Células Epiteliales/patología , Biomarcadores de Tumor/metabolismo , Mama/metabolismo , Carcinoma Ductal de Mama/metabolismo , Carcinoma Ductal de Mama/patología , División Celular , Ciclina D1/metabolismo , Células Epiteliales/metabolismo , Femenino , Productos del Gen rex/metabolismo , Humanos , Hiperplasia , Técnicas para Inmunoenzimas , Antígeno Ki-67/metabolismo , Proteína Oncogénica p21(ras)/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Receptor ErbB-2/metabolismo , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
Malaria affects world-wide more than 200 million people, of which 1-2 million die every year. New drugs and treatment strategies are needed to face the rapidly increasing problems of drug resistance. During a malaria infection, both host and parasite are under oxidative stress. Increased production levels of reactive oxygen species (ROS, e.g superoxide anion and the hydroxyl radical) are produced by activated neutrophils in the host and during degradation of haemoglobin in the parasite. The effects of ROS in malaria can be both beneficial and pathological, depending on the amount and place of production. Enhanced ROS production after the administration of pro-oxidants, which is directed against the intra-erythrocytic parasite, inhibits the infection both in vitro and in vivo. However, ROS are also involved in pathological changes in host tissue like damage of the vascular endothelial lining during a malaria infection (cerebral malaria). Pro-oxidants support the host defense against the parasite when working in or near the infected cell but potentially cause vascular damage when working on or near the vascular lining. Examples of pro-oxidants are found among xenobiotics and food components. Important new drugs belonging to the class of pro-oxidants are artemisinin and its derivatives. Anti-oxidants potentially counteract these agents. Treatment with anti-oxidants or chelators of metals to prevent their catalytic function in the generation of ROS may prevent vascular pathology. In addition, the iron chelator desferrioxamine, exhibits an antiparasitic activity, because iron is also essential for the proliferation of the parasite. Cytokines play an important role in ROS-related pathology of malaria, though their mechanism of action is not completely elucidated. This field might bring up new treatment concepts and drugs. Drugs which prevent host pathology, such as the cerebral complications might be life saving.
Asunto(s)
Antioxidantes/uso terapéutico , Malaria/sangre , Malaria/tratamiento farmacológico , Estrés Oxidativo/fisiología , Especies Reactivas de Oxígeno , Especies Reactivas de Oxígeno/fisiología , Animales , Citocinas/fisiología , Humanos , Malaria/inmunología , Malaria/prevención & control , Ratones , Especies Reactivas de Oxígeno/inmunologíaRESUMEN
The prevalence and microfilarial density of Loa loa and Mansonella perstans filariasis have been determined in three successive surveys in one village in the dense rainforest of Southern Cameroon. The prevalence of L. loa microfilaraemia was 30.9% with a geometric mean density of 81.4 microfilariae/30 microliter blood. There was no difference between men and women. The prevalence increased with age from 14.5% at 0-9 years to 52.9% at 40-49 years, whereafter it stablized. The microfilarial density increased until the age of 30-39 years. The highest densities have been found around noon, although the difference was not significant. The prevalence of M. perstans microfilaraemia was 26.6% with a median density of 2.0 microfilariae/30 microliter blood. Both prevalence and density were increasing with age and were higher for men than for women. The time of day that the blood sample was taken had no influence on the microfilarial density of M. perstans.