Assessment of the effectiveness of primary health care interventions in the control of three intestinal nematode infections in rural communities
Methods: In a 30 months' longitudinal study, primary health care intervention was effective in reducing the prevalence of three common intestinal nematode infections (Ascaris lumbricoides, Trichuris trichiura and Necator americanus) in three communities. This was achieved by training school leavers and auxiliary aides as microscopists, health inspectors and field assistants and deploying them to provide screening, surveillance, environmental sanitation, and mass-expulsion chemotherapy (MEC).
Results: Post-control surveillance confirmed that the prevalence of these infections had been greatly reduced. The prevalence of Ascaris lumbricoides had declined from 49.3% (pre-intervention) to 10.5% (post-intervention). Hookworm had fallen from 31.4% (pre-intervention) to 4.1% (post-intervention) and whipworm from 40.7% (pre-intervention) to 6.5% (post-intervention). Overall percentage decreases of 78.7%, 86.9% and 84.0% were recorded for Ascaris lumbricoides, Necator americanus and Trichuris trichiura respectively.
Interpretation: The initial decline in prevalence was due to the MEC campaign, but the improved sanitation and health education presumably reduced the reinfection rate. If the entire population participated, periodic repetition of the mass expulsion therapy campaign at appropriate intervals combined with continued attention to environmental hygiene and prolonged health education could bring these infections under control within a few years. In the late 1980s and early 1990s in Nigeria, parasitologist evaluated the effectiveness of health education, environmental sanitation, and mass expulsion chemotherapy (MEC) in controlling endemic parasitic infections (Ascaris lumbricoides, Trichuris trichiura, and Necator americanus) in the population served by health care centers in Ndele, Emohua, and Aluu (in the eastern area of the Niger Delta Basin). 240 dropouts from primary and secondary schools and 45 auxiliary nurses from the communities underwent 6 months, training to become health inspectors, microscopists, field assistants, and surveillance staff. About 120 people/day frequented each community health education forum at the centers. The communities worked together to build ventilation-improved pit latrines, resulting in a considerable decline of open air defecation. 54.5% of the population provided stool samples so researchers could determine the prevalence of intestinal nematode infections. Health workers administered a single dose of either Alcopar or Zentel to all people diagnosed with nematode infection. The infected people also received nutritional supplements as required. Initial prevalence was 49.3% for A. lumbricoides, 40.7% for T. trichiura, and 31.4% g for N. americanus. The interventions contributed to a decline in overall prevalence ranging from 70.6% (A. lumbricoides in Ndele) to 88.2% (N. americanus in Emohua). The percentage of reduction of A. lumbricoides infection increased as age increased (e.g., 73.5% reduction for 5 year old children and 86% reduction for 45 to 54 year olds). Little difference in reduction with age existed for N. americanus and T. trichiura infections, however, 30 months after intervention prevalence was 10.5% for A. lumbricoides, 6.3% for T. trichiura, and 3.9% for N. americanus. These findings indicated that health education campaigns, MEC campaigns, and improvement in environmental sanitation result in considerable reduction of nematode infections.