Comparative Study of the Sensitivity of Different Diagnostic Methods for the Laboratory Diagnosis of Buruli Ulcer Disease

Background. Several diagnostic laboratory methods are available for case confirmation of Buruli ulcer disease. This study assessed the sensitivity of various diagnostic tests in relation to clinical presentation of the disease, type of diagnostic specimen, and treatment history. Methods. Swab samples, 3-mm punch biopsy tissue specimens, and surgically excised tissue specimens from 384 individuals with suspected Buruli ulcer disease were obtained at 9 different study sites in Ghana and were evaluated with dry reagent-based polymerase chain reaction (PCR), microscopic examination, culture, and histopathological analysis. The study subjects presented with nonulcerative and ulcerative lesions and were divided into 3 treatment groups: (1) previously untreated patients scheduled for antimycobacterial treatment, (2) patients treated with surgery alone, and (3) patients treated with surgery in combination with previous antimycobacterial treatment. Results. Of 384 suspected cases of Buruli ulcer disease, 268 were confirmed by at least 1 positive test result. The overall sensitivity of PCR (85%) was significantly higher than that of microscopic examination (57%) and culture (51%). After data were stratified by treatment group, type of lesion, and diagnostic specimen type, analysis revealed that PCR of 3-mm punch biopsy tissue specimens (obtained from previously untreated nonulcerative lesions) and of swab samples (obtained from previously untreated ulcers) had the highest diagnostic sensitivity (94% and 90%, respectively). Although duration of the disease did not significantly influence the sensitivity of any test, previous antimycobacterial treatment was significantly associated with decreased sensitivity of PCR and culture. Conclusions. Across all subgroups, PCR had the highest sensitivity. PCR assessment of 3-mm punch biopsy tissue specimens proved to be the best diagnostic tool for nonulcerative lesions, and PCR assessment of swab samples was the best diagnostic tool for ulcerative lesions. For monitoring of antimycobacterial treatment success within controlled trials, however, only culture is appropriat

Histopathologic Features of Mycobacterium ulcerans Infection

Because of the emergence of Buruli ulcer disease, the World Health Organization launched a Global Buruli Ulcer Initiative in 1998. This indolent skin infection is caused by Mycobacterium ulcerans. During a study of risk factors for the disease in Ghana, adequate excisional skin-biopsy specimens were obtained from 124 clinically suspicious lesions. Buruli ulcer disease was diagnosed in 78 lesions since acid-fast bacilli (AFB) were found by histopathologic examination. Lesions with other diagnoses included filariasis (3 cases), zygomycosis (2 cases), ulcerative squamous cell carcinomas (2 cases), keratin cyst (1 case), and lymph node (1 case). Thirty-seven specimens that did not show AFB were considered suspected Buruli ulcer disease cases. Necrosis of subcutaneous tissues and dermal collagen were found more frequently in AFB-positive specimens compared with specimens from suspected case-patients (p<0.001). Defining histologic criteria for a diagnosis of Buruli ulcer disease is of clinical and public health importance since it would allow earlier treatment, leading to less deforming sequelae

Buruli Ulcer Disease and Its Association with Land Cover in Southwestern Ghana.

BACKGROUND:Buruli ulcer (BU), one of 17 neglected tropical diseases, is a debilitating skin and soft tissue infection caused by Mycobacterium ulcerans. In tropical Africa, changes in land use and proximity to water have been associated with the disease. This study presents the first analysis of BU at the village level in southwestern Ghana, where prevalence rates are among the highest globally, and explores fine and medium-scale associations with land cover by comparing patterns both within BU clusters and surrounding landscapes. METHODOLOGY/PRINCIPAL FINDINGS:We obtained 339 hospital-confirmed BU cases in southwestern Ghana between 2007 and 2010. The clusters of BU were identified using spatial scan statistics and the percentages of six land cover classes were calculated based on Landsat and Rapid Eye imagery for each of 154 villages/towns. The association between BU prevalence and each land cover class was calculated using negative binomial regression models. We found that older people had a significantly higher risk for BU after considering population age structure. BU cases were positively associated with the higher percentage of water and grassland surrounding each village, but negatively associated with the percent of urban. The results also showed that BU was clustered in areas with high percentage of mining activity, suggesting that water and mining play an important and potentially interactive role in BU occurrence. CONCLUSIONS/SIGNIFICANCE:Our study highlights the importance of multiple land use changes along the Offin River, particularly mining and agriculture, which might be associated with BU disease in southwestern Ghana. Our study is the first to use both medium- and high-resolution imagery to assess these changes. We also show that older populations (≥ 60 y) appear to be at higher risk of BU disease than children, once BU data were weighted by population age structures

Spatial distribution and spatial cluster of BU cases and prevalence.

<p>The map to the left shows the spatial distribution of BU cases in each village/town. The large yellow circle is the primary cluster of BU disease, which is located at 5.930°N and 1.861°W with a radius of 22.94 km. It includes 33 villages and 174 BU cases. The map to the right is the spatial distribution of BU prevalence in each village/town. The prevalence is calculated using the number of BU cases divided by the population in each village.</p

The study extent used to assess the relationship between Buruli Ulcer and land use in southwest Ghana.

<p>The study extent was determined by the Landsat images, which covered ~95% of the villages/towns with BU cases in the clinical dataset.</p

The association of BU prevalence and land cover classes in different spatial extents using spatial lag regression models.

<p>The two models with smaller AIC values from the negative binomial regression analysis were selected for spatial lag regression analysis. The dependent variable is the natural logarithm -transformed number of BU cases in each village. The covariates are the percentages of land cover classes in a buffer in different distances.</p

Land cover map of the primary BU cluster based on the classification of the Rapid Eye image.

<p>Bottom inset shows extent of satellite imagery within the cluster. The area has a few villages/towns with a high number of BU cases, e.g. Ayanfuri and Pokukrom.</p

Land cover classes used in image classification.

<p>Land cover classes used in image classification.</p

Comparison of land cover in the BU clustered area (574 km²) with the whole study area (31,580 km²).

<p>Here, the clustered area denotes the area covered by the Rapid Eye image in the primary cluster of BU disease as shown in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003840#pntd.0003840.g005" target="_blank">Fig 5</a>; the whole area is the area covered by the Landsat image as shown in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003840#pntd.0003840.g001" target="_blank">Fig 1</a>.</p

Cytokine Responses to Stimulation of Whole Blood from Patients with Buruli Ulcer Disease in Ghana

Buruli ulcer disease (BUD), caused by Mycobacterium ulcerans, follows an indolent course of initial progression to ulceration accompanied by extensive tissue damage. It has been suggested that healing disease stages are accompanied by a protective immune response. We hypothesized that interleukin-4 (IL-4)- or IL-10-induced downregulation of Th-1 responses plays a key role in the progression of early BUD and that healing is accompanied by an augmented Th-1 response. Gamma interferon (IFN-γ), IL-4, and IL-10 responses were measured after in vitro stimulation with phytohemagglutinin (PHA) and tuberculin purified protein derivative (PPD) of whole blood from 39 (23 early- and 16 late-stage) BUD patients and 39 healthy control subjects in Ghana. Additionally, 30 patients with active or treated tuberculosis (TB) serving as PPD-responsive positive controls were studied. Early-stage BUD patients produced significantly lower levels of IFN and IFN-γ/IL-4 ratios compared to late-stage BUD patients after PHA stimulation. Compared to that of controls, IFN-γ production after tuberculin stimulation was significantly higher in late-stage but not in early-stage BUD patients (P = 0.009). IL-10 and IL-4 levels did not differ between BUD patients and controls, although active TB patients had significantly higher IL-10 production levels than did treated TB patients. Multivariate analysis showed no confounding factors. In conclusion, Th-1 down regulation in early BUD appears to reverse in later stages of BUD, although an association with IL-10 or IL-4 production does not emerge from our data. Here we show differences in Th-1-type cytokine production between early- and late-stage BUD that might reflect an improved immune defense over time