Detection of Wuchereria bancrofti in human blood samples and mosquitoes in Matayos, Busia County-Kenya

Abstract

Lymphatic filariasis is a mosquito borne disease which leads to abnormal painful enlarged body parts, severe disability and social stigma. We screened Wuchereria bancrofti in Matayos constituency in Busia County. Blood samples were collected from 23 villages selected purposively based on clinical case reports. Finger prick and/or venous blood sampling and mosquito collections was carried out. Antigenaemia and filarial DNA prevalence were determined. Infection rates on mosquito pools were estimated and SPSS version 26 was used for descriptive statistics analysis. A total of 262 participants were recruited, 73.3% (n = 192) of the participants had no symptoms, 14.1% (n = 5.3) had swollen legs, 5.3% (n = 14) had painful legs and 3.8% (n = 10) with scrotal swellings. Average antigenemia prevalence was 35.9% (n = 94) and DNA prevalence was at 8.0% (n = 21). A total of 1305 mosquitoes were collected and pooled into 2-20 mosquitoes of the same species and from the same village. Two pools out of 78 were positive for filarial DNA with a minimum infection rate of 0.15%. From this study, antigenaemia and infected mosquitoes are an indication of active transmission. The clinical signs are evidence that filarial infections have been in circulation for over 10 years. The global climate change phenomenon currently happening has been shown to adversely affect the transmission of vector borne diseases and is likely to increase lymphatic filariasis transmission in the area. This study therefore recommends further screening before Mass Drug Administration, morbidity management and enhanced mosquito control Programmes are recommended in the study area.

Figure 1

Map of Kenya showing Busia County; Matayos south and Busibwabo wards as the study sites pointed by blue arrows. Source: Map generated with QGIS software program using the Matayos study site Co-ordinates taken during the study, courtesy of Jacob Mueti.

Figure 2

Bar graph showing number of participants per age group.

Figure 3

Shows some of the victims with chronic clinical manifestations of lymphatic filariasis disease in the study area. Chronic cases among the study participants; Image (a) lymphedema of both legs, images (b) lymphedema affecting one leg and image (c) scrotal swelling (Hydrocele cases). Source: Photos courtesy of Nancy Kinyatta & Johnstone Ingonga.

Figure 4

Graph of the signs and symptoms per age group.

Figure 5

Shows a gel electrophoresis fragmentation of amplified W. bancrofti DNA from blood samples and mosquito pools. Image of W. bancrofti amplified targeted region of 188 bp on 2% agarose gel electrophoresis. ML is Molecular size standard marker (100 bp), Lanes 1–5 are W. bancrofti DNA from blood specimen while lane 6–7 represents W. bancrofti DNA from mosquito pools, Lane PC is W. bancrofti DNA positive control and Lane NC represents negative control which was deionized PCR water.

Figure 6

Graph showing mosquito genus collected in each village.