Dickson Osabutey

: To identify potential sources of hookworm infections in a Ghanaian community of endemicity that could be targeted to interrupt transmission, we tracked the movements of infected and noninfected persons to their most frequented locations. Fifty-nine participants (29 hookworm positives and 30 negatives) wore GPS trackers for 10 consecutive days. Their movement data were captured in real time and overlaid on a community grid map. Soil samples were collected and divided into two parts: one for determining the physical and chemical properties and the other for culture of helminth larvae. Soil parameters were determined using standard methods, and the number of larvae recovered from Baermann cultures (expressed as larvae per gram of soil) was recorded. We found no significant difference in the larval counts between sites of infected and noninfected participants (P = 0.59). Sandy-loam soil, pH, and effective cation exchange capacity were associated with high larval recovery counts (P P Panagrolaimus superbus, Parastrongyloides trichosuri, Trichuris trichiura (human whipworm), and Ancylostoma caninum (dog hookworm). Despite Necator americanus being the predominant species in the community, no larvae of this species were identified. This study, however, demonstrates the feasibility of applying molecular tools for identifying environmental factors and places associated with exposure to human and zoonotic helminths, including areas that may be targeted to break transmission in communities where infection is endemic.

The global health community has targeted the elimination of neglected tropical diseases (NTDs) including soil-transmitted helminthiasis by 2030. The elimination strategy has not changed from that of control using regular mass drug administration (MDA) with albendazole, WASH and education. Already doubts have been expressed about this achievement, principally because drugs do not interrupt transmission. We report here the findings of a cohort study aimed to identify host modifiable and environmental factors associated with hookworm infection and reinfection in rural communities in Kintampo North Municipality, Ghana. Faecal samples of 564 consented participants were screened for intestinal parasites at baseline, 9 months and 24 months using the Kato-Katz method. At each time point, positive cases were treated with a single dose of albendazole (400 mg) and their samples were again screened 10-14 days post-treatment to record treatment failures. The hookworm prevalence at the three-time points was 16.7%, 9.22% and 5.3% respectively, whilst treatment failure rates were 17.25%, 29.03% and 40.9% respectively. The intensities of hookworm infection (in eggs per gram) at the time points were 138.3, 40.5 and 135, which showed a likely association with wet and dry seasons. We posit that the very low intensity of hookworm infections in humans during the dry season offers a window of opportunity for any intervention that could drastically reduce the community worm burden before the rainy season.

Ghana has been implementing mass drug administration (MDA) of ivermectin and albendazole for the elimination of lymphatic filariasis (LF) since the year 2000, as part of the Global Programme to Eliminate Lymphatic Filariasis (GPELF). It was estimated that 5–6 years of treatment would be sufficient to eliminate the disease. Tremendous progress has been made over the years, and treatment has stopped in many disease endemic districts. However, despite the successful implementation of MDA, there are districts with persistent transmission. In this study we assessed the epidemiology of LF in three adjoining districts that have received at least 16 years of MDA. The assessments were undertaken one year after the last MDA. 1234 adults and 182 children below the age of 10 years were assessed. The overall prevalence of circulating filarial antigen in the study participants was 8.3% (95% CI: 6.9–9.9), with an estimated microfilaria prevalence of 1.2%. The microfilarial intensity in positive individuals ranged from 1 to 57 microfilariae/mL of blood. Higher antigen prevalence was detected in males (13.0%; 95% CI: 10.3–16.2) compared to females (5.5%; 95% CI: 4.1–7.2). The presence of infection was also highest in individuals involved in outdoor commercial activities, with the risks of infection being four- to five-fold higher among farmers, fishermen, drivers and artisans, compared to all other occupations. Using bednets or participating in MDA did not significantly influence the risk of infection. No children below the age of 10 years were found with infection. Detection of Wb123 antibodies for current infections indicated a prevalence of 14.4% (95% CI: 8.1–23.0) in antigen-positive individuals above 10 years of age. No antibodies were detected in children 10 years or below. Assessment of infection within the An. gambiae vectors of LF indicated an infection rate of 0.9% (95% CI: 0.3–2.1) and infectivity rate of 0.5% (95% CI: 0.1–1.6). These results indicate low-level transmission within the districts, and suggest that it will require targeted interventions in order to eliminate the infection.