The causes of hookworm infection are closely linked to environmental conditions, socio-economic factors, and human behaviour. Understanding these causes is essential for developing effective prevention strategies in regions where the disease is endemic.
The Role of the Parasite’s Life Cycle
Hookworm is caused by parasitic nematodes, primarily Necator americanus and Ancylostoma duodenale. The life cycle begins when an infected person passes faeces containing worm eggs into the environment. Under warm, moist, and shaded soil conditions, the eggs hatch within one to two days and develop into infective filariform larvae. These larvae can survive in soil for several weeks.
Transmission occurs when these larvae penetrate human skin, usually through bare feet or hands. After entering the body, they travel through the bloodstream to the lungs, migrate up the respiratory tract, and are swallowed, eventually reaching the small intestine, where they mature into adult worms and begin producing eggs.
Exposure to Contaminated Soil
One of the primary causes of hookworm infection is direct contact with contaminated soil. Walking barefoot or playing on untreated ground greatly increases the risk. This is especially common in tropical and subtropical regions where infrastructure is poor.
Lack of Sanitation
Inadequate sanitation is a major contributor. Open defecation and the absence of proper toilets allow hookworm eggs to contaminate soil. Once eggs hatch and develop into larvae, they can infect anyone who comes into contact with the contaminated ground. Over time, these environments become persistent reservoirs of infection.
Climatic and Environmental Conditions
Hookworm larvae thrive in warm, moist climates with sandy or loamy soil. Rainfall, humidity, and temperature all influence larval survival, explaining why hookworm prevalence is highest in tropical and subtropical regions such as:
- Sub-Saharan Africa
- Southeast Asia
- Pacific Islands
- Central and South America
Agricultural Practices
The use of untreated human faeces as fertiliser (known as “night soil”) remains a risk factor in some rural communities. This practice introduces hookworm eggs into soil and crops, increasing the likelihood of human infection through farming activities.
Occupational and Lifestyle Risks
Farmers, labourers, and others who work outdoors in soil-rich environments are at heightened risk. Without protective footwear or gloves, these individuals are more likely to acquire infection. Occupations in agriculture, construction, and mining are particularly vulnerable.
Poor Hygiene and Limited Awareness
Limited access to clean water and soap makes it harder for individuals to maintain good hygiene. Failure to wash hands and feet after soil contact increases the risk of infection. Moreover, lack of knowledge about transmission routes means many communities do not take preventive measures, such as wearing shoes.
Poverty as an Underlying Driver
Poverty is at the core of hookworm transmission. Communities with limited access to education, healthcare, sanitation, and clean water remain trapped in a cycle of infection and illness. Hookworm, in turn, worsens poverty by reducing work productivity, cognitive development in children, and overall economic stability.
Displacement and Overcrowding
Refugee camps, temporary settlements, and areas affected by conflict or natural disasters often have inadequate sanitation and overcrowding, creating ideal conditions for hookworm spread.
Gaps in Public Health Interventions
While mass deworming programmes temporarily reduce infection rates, their impact is short-lived without improvements in water, sanitation, and hygiene (WASH). Failure to sustain integrated control measures allows reinfection to occur quickly.
Summary of Key Causes
To summarise, the causes of hookworm infection are multifactorial and include:
- Biological factors (parasite life cycle)
- Environmental factors (warm, moist soil conditions)
- Societal factors (poverty, poor sanitation, lack of health education)
Preventing hookworm requires a comprehensive approach that combines medical treatment with long-term improvements in sanitation, hygiene, and community awareness.
