Dynamics of Wuchereria bancrofti transmission in households and neighborhoods of microfilaraemic individuals with lymphatic filariasis

Background & objectives: To analyze factors associated with the distribution of lymphatic filariasis (LF) in households with microfilaraemic patients and their neighbors, identifying whether there are differences in the occurrence and, consequently, in the transmission of Wuchereria bancrofti in these environments. Methods: Thick blood smears and membrane filtration technique were used to identify and to determine density of W. bancrofti microfilariae in peripheral blood of family members living in same households of microfilaraemic patients and in their neighborhood. Infection rates in mosquitoes captured in these different surroundings were also analyzed. Results: Significant differences were found in frequency of LF infection when comparing microfilaraemic families (24.7%) to its neighbors (3.9%) [p = 0.0000001; OR = 8.1 (CI 95%: 6.2 – 10.4)] and also to the general population of the endemic area (2.6%) [p = 0.0000001; OR = 12.4 (CI 95%: 10.1 – 15.2)]. The microfilaraemia of the household contacts (34.1±58.5 mf/mL) was significantly higher than the neighbors' microfilariae (mf) countings (20.2±27.6 mf/mL) (p < 0.003). The rates of infection and infectivity in mosquitoes were also higher in the microfilaraemic houses (p < 0.0000001). Interpretation & conclusion: The findings of this study indicate that family aggregation of microfilariae carriers leads to high prevalences of LF, which is important in the maintenance and transmission of the disease. Familial contacts can play an important role in filariasis transmission and consequently in its control. This must be taken into consideration to establish specific and effective measures for LF elimination.