Accurate and cost-effective identification of areas where co-endemic infections occur would enable public health managers to identify opportunities for implementation of integrated control programs. Dried blood spots collected during cross-sectional lymphatic filariasis surveys in coastal Kenya were used for exploratory integrated detection of IgG antibodies against antigens from several parasitic infections (, , spp., , and ) as well as for detection of responses to immunizing agents used against vaccine-preventable diseases (VPDs) (measles, diphtheria, and tetanus) using a multiplex bead assay (MBA) platform. High heterogeneity was observed in antibody responses by pathogen and antigen across the sentinel sites. Antibody seroprevalence against filarial antigens were generally higher in Ndau Island ( < 0.0001), which also had the highest prevalence of filarial antigenemia compared with other communities. Antibody responses to the species antigens circumsporozoite protein (CSP) and merozoite surface protein-1 (MSP-1) were higher in Kilifi and Kwale counties, with Jaribuni community showing higher overall mean seroprevalence ( < 0.0001). Kimorigo community in Taita-Taveta County was the only area where antibody responses against Sm25 recombinant antigen were detected. Seroprevalence rates to antigen NIE ranged between 3% and 26%, and there was high heterogeneity in immune responses against an antigen among the study communities. Differences were observed between communities in terms of seroprevalence to VPDs. Seroprotection to tetanus was generally lower in Kwale County than in other counties. This study has demonstrated that MBA holds promise for rapid integrated monitoring of trends of infections of public health importance in endemic areas.
To determine the current status of LF using a combination of seroepidemiological tools to determine prevalence of circulating filarial antigen (CFA) and antifilarial antibodies.
Preliminary study findings:
- 2,976 individuals (age: 2 to 100 years) were tested for circulating filariail antigen using the immunochromatographic (ICT) test during daytime visits. Night-time blood samples to detect microfilariae (MF) were requested from those who tested positive via the ICT test.
- Out of the 38 persons found to be positive for LF infection by ICT test, 33 provided a night-time blood sample for examination of MF. Overall, nine individuals were found to be MF positive, with the highest prevalence in Ndau Island.
- The current study suggests that LF transmission may be absent in Taita-Taveta and Tana River counties in coastal Kenya and therefore transmission assessment surveys (TAS) should be considered with a view to stopping MDA. By contrast, evidence for ongoing transmission in Kwale, Kilifi and Lamu counties indicates the need for further MDA rounds in these counties.
- Additionally, the study demonstrated the feasibility of conducting integrated serosurveillance of several infectious diseases of public health interest, as well as levels of seroprotection against vaccine preventable diseases. The findings of the current study underscore the added value of using multiplex antibody measurements to guide and monitor LF elimination efforts.