Current Epidemiological Assessment of Bancroftian Filariasis in Tanga Region, Northeastern Tanzania

Abstract

Background. Tanzania started a countrywide lymphatic filariasis elimination programme in 2000 adopting the mass drug administration (MDA) strategy. The drug used for the programme was the combination of ivermectin and albendazole. However, there is limited information on the current epidemiological trend of the infections, where MDA implementation is ongoing. The present study aimed at assessing the current status of Bancroftian filariasis infection rate and morbidity where MDA has been distributed and administered for over eight rounds. Methodology. The study was a cross-sectional descriptive study involving 272 individuals (>18 years) from endemic communities in Tanga region where MDA has been implemented. Clinical, sociodemographic, and circulating filarial antigen (CFA) test was undertaken using immune chromatographic card test according to the manufacturer's instructions. Results. A total of 472 individuals were screened: 307/472 (65.1%) were males while 165/472 (34.9%) were females. The overall prevalence of CFA was 5.51%, that of hydrocoele was 73.2%, and that of lymphoedema was 16.0%. The prevalence of hydrocoele combined with lymphoedema was 5.5%. Conclusion. Our findings demonstrate a considerable reduction in filarial infection. However, there is clear evidence of ongoing transmission despite the 8 rounds of MDA. It is unlikely that the annual MDA would interrupt filarial transmission; therefore, additional strategies are needed to accelerate lymphatic filariasis control and elimination.

Prevalence and Correlates of Lymphatic Filariasis Infection and Its Morbidity Following Mass Ivermectin and Albendazole Administration in Mkinga District, North-Eastern Tanzania

“…In Figure 5A, the scrotal enlargements in the younger age group (5-11 years) were not hydrocele, but rather a condition possibly triggered by other conditions, such as congenital inguinal hernias, which are frequently seen in this age group [47], tumors, or tuberculosis. In this age group, hydroceles were not as common as in individuals aged 16-24 years [24,29]. The frequencies of hydrocele observed in this study were similar to those reported in other studies done previously in the study area and elsewhere [18,24].…”

“…In this age group, hydroceles were not as common as in individuals aged 16-24 years [24,29]. The frequencies of hydrocele observed in this study were similar to those reported in other studies done previously in the study area and elsewhere [18,24]. High proportions of scrotal swelling, which were not hydrocele, were observed in six study sites (Kichakamiba, Mongavyeru, Tawalani, Maramba A, Mayomboni, and Moa).…”

“…A cross-sectional spot-check survey after eight rounds of MDA reported a respective prevalence of 15.5% and 3.5% for CFA and mf, respectively, in three communities (a decrease of 75.5% and 89.6% from baseline, respectively) and 2.3% for CFA in school children (decrease of 90.9% from baseline) [25]. In some endemic areas, a reduction of infection prevalence to low levels as 1% was noted, but along the coast of the Indian ocean after eight rounds of MDA, the prevalence of infection was still higher than what was expected [24,26]. In line with this, transmission by the three vectors (Anopheles gambiae, An.…”

“…Previously, few communities and school-based surveillance studies assessed the short and mid-term impact of MDA in different districts of Tanga region after three [19], six [23], and eight [24] rounds of MDA. Human microfilariae initially decreased rapidly following this intervention, leading to a considerable reduction in transmission, but the effects thereafter leveled off, and transmission continued at a low level after the third MDA [19].…”

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“…years of annual MDA, such as in Nigeria, Tanzania and Ghana [18][19][20]. In Ghana, after up to 14 rounds of MDA, the transmission of LF still persists in districts with relatively high baseline prevalence [21].…”