Zheng Qi  2021-04-13

Hookworms, the most common STH species that trigger chronic anemia, attach firmly to the intestinal mucosal wall with their specialized mouthparts and secrete anticoagulant substances to continuously feed on human blood. Each adult hookworm causes 0.02 to 0.05 milliliters of daily blood loss, and patients carrying over 100 hookworms can lose more than 50 milliliters of blood per month, far exceeding the body’s normal red blood cell regeneration capacity. According to 2025 WHO public health data, over 200 million people globally develop STH-related iron-deficiency anemia, which accounts for 38% of childhood anemia cases in high-prevalence rural regions.

Worm infections also exacerbate vitamin A deficiency, a widespread public health nutrition issue affecting over 250 million people worldwide. Parasites residing in the intestine compete directly with the human host for the limited vitamin A intake from daily food, especially in low-income communities where residents rarely consume vitamin A-rich animal products, dark green vegetables or fortified foods. Long-term aggravated vitamin A deficiency can lead to impaired dark adaptation, dry eye syndrome, weakened mucosal immune barriers and increased risk of repeated respiratory and gastrointestinal infections, with severe cases even progressing to irreversible corneal damage.

For school-age children living in STH endemic areas, chronic worm infections significantly impair their learning capacity. The combined effects of persistent mild anemia, nutrient depletion and chronic intestinal inflammation reduce children’s oxygen supply to the brain, making them less able to concentrate or memorize new information during classes. Epidemiological surveys show that STH-infected children score 15% to 20% lower on average in standardized school tests than their non-infected peers, and are 30% more likely to miss school days due to related discomfort, creating long-term barriers to their intellectual development and academic performance.

Severe, long-term repeated STH infections can lead to life-threatening intestinal obstruction, which occurs most frequently in young children whose intestinal tracts are still relatively narrow. When the total number of accumulated adult worms in the intestine reaches several hundred, the tangled mass of parasites can fully block the intestinal lumen, triggering severe abdominal pain, vomiting and even acute ileus that requires emergency surgical intervention. WHO surveillance data records that over 12,000 severe STH-related intestinal obstruction cases are reported globally every year, 85% of which occur in children under 10 years old in un-dewormed endemic communities.

Edited by: Secretariat of the Asia-Pacific Network for Drug and Diagnostics Innovation
Produced by: Zheng Qi
Reviewed by: Zhang Haobing
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