Heterogeneous response of Wuchereria bancrofti-infected persons to diethylcarbamazine (DEC) and its implications for the Global Programme to Eliminate Lymphatic Filariasis (GPELF).

DEC or ivermectin (IVM) in combination with albendazole (ALB) has been the recommended strategy of the Global Programme to Eliminate Lymphatic Filariasis (GPELF) since 2000. Despite effective population coverage (> 65%) with several rounds of MDA with DEC or combination of DEC plus ALB, microfilariae persist in few individuals and they continue to be the source of infection for transmitting LF. We report an individual's variability in response to DEC by defining the response as complete absence of microfilaria (mf) (post-treatment mf count = 0) and non-response as presence of mf (post-treatment mf count ≥ 1). We analyzed follow-up data on individual's response to treatment from two randomized clinical trials in which 46 microfilaremic individuals were treated with single-dose DEC (6 mg/kg body weight). They were classified into low, medium, and high mf density categories based on their pre-treatment mf counts. Of the 46 individuals, 65.2% have not responded throughout the 12-month post-treatment period. Application of a logistic regression model with fixed (age, gender, mf density, post-treatment time, and their interactions) and random (individual's response over time) effects indicated that treatment response is independent of age, gender, and time. The overall treatment response increases in low and decreases in high mf density categories. Furthermore, the estimates for the random coefficients model showed that there is a greater variability in response between individuals over post-treatment time. The results substantiate that individual variation in response to DEC exists which indicate the importance of studying the parasite as well as host genetic factors associated with DEC action.

Incidence, risk factors and clinical epidemiology of melioidosis: a complex socio-ecological emerging infectious disease in the Alor Setar region of Kedah, Malaysia.

BACKGROUND: Melioidosis, a severe and fatal infectious disease caused by Burkholderia pseudomallei, is believed to an emerging global threat. However, data on the natural history, risk factors, and geographic epidemiology of the disease are still limited. METHODS: We undertook a retrospective analysis of 145 confirmed cases extracted from a hospital-based Melioidosis Registry set up from 2005 in Hospital Sultanah Bahiyah, Alor Setar, Kedah state, Malaysia, in order to provide a first description of the contemporary incidence, risk factors, and clinical epidemiology of the disease in this putatively high risk region of the country. RESULTS: The incidence of melioidosis in Alor Setar is remarkably high at 16.35 per 100,000 population per year. The mean age of patients was 50.40 years, with infection varying nonlinearly with age. Males (75.2%; P < 0.0001) predominated and the majority of cases were Malays (88.9%). The overall, crude mortality rate among the study patients was 33.8%. The proportions of cases and deaths were significantly greater among patients involved in farming, forestry and fishing and the unemployed (χ2 = 30.57, P < 0.0001). A majority of cases (62.75%) were culture positive, with mortality in these patients being 45.05%. A large proportion (83.0%) of culture positives was also bacteremic. Pneumonia accounted for 42.06% of primary diagnoses followed in importance by soft tissue abscess. In patients with pneumonia and who were culture positive, the mortality rate was as high as 65.00%. Diabetes mellitus constituted the major underlying risk factor for developing and dying from melioidosis, occurring in 57% of all diagnosed cases. The age distribution of diabetes paralleled that of melioidosis cases. There were linear associations between cases and deaths with monthly rainfall. CONCLUSIONS: Melioidosis represents a complex socio-ecological public health problem in Kedah, being strongly related with age, occupation, rainfall and predisposing chronic diseases, such as diabetes mellitus. Among cases, bacteremic patients were associated with significantly high mortality despite provision of the recommended antibacterial therapy. The burden of this disease is likely to grow in this region unless better informed interventions targeted at high-risk groups and associated diseases are urgently implemented.