Hookworm - Prevention

Prevention

The infective larvae develop and survive in an environment of damp dirt, particularly sandy and loamy soil. They cannot survive in clay or muck. The main lines of precaution are those dictated by sanitary science:

• Do not defecate in places other than latrines, toilets etc.
• Do not use human excrement or raw sewage or untreated 'night soil' as manure/fertilizer in agriculture
• Do not walk barefoot in known infected areas
• Deworm pet dogs — canine and feline hookworms rarely develop to adulthood in humans (Ancylostoma caninum, the common dog hookworm, occasionally develops into an adult to cause eosinophilic enteritis in people), but their invasive larvae can cause an itchy rash called cutaneous larva migrans.

Moxidectin has been released in the United States as part of Advantage Multi (imidacloprid + moxidectin) Topical Solution for dogs and cats. It utilizes moxidectin for control and prevention of roundworms, hookworms, heartworms, and whipworms.

With an estimated 740 million individuals infected, hookworm is a major public health concern in our world today. While hookworm infection may not directly lead to mortality, its effects on morbidity demand immediate attention. When considering disability-adjusted life years (DALYs), neglected tropical diseases, including hookworm, rank among diarrheal diseases, ischemic heart disease, malaria, and tuberculosis as one of the most important health problems of the developing world.

It has been estimated that as many as 22.1 million DALYs have been lost due to hookworm. Recently, there has been increasing interest to address the public health concerns associated with hookworm. For example, the Bill & Melinda Gates Foundation recently donated US$34 million to fight Neglected Tropical Diseases including hookworm infection. Former US President Clinton also announced a mega-commitment at the Clinton Global Initiative (CGI) 2008 Annual Meeting to de-worm 10 million children.

Most of these public health concerns have focused on children who are infected with hookworm. This focus on children is largely due to the large body of evidence that has demonstrated strong associations between hookworm infection and impaired learning, increased absences from school, and decreased future economic productivity. In 2001, the 54th World Health Assembly passed a resolution demanding member states to attain a minimum target of regular deworming of at least 75% of all at-risk school children by the year 2010. A 2008 World Health Organization publication reported on these efforts to treat at-risk school children. Some of the interesting statistics were as follows: 1) only 9 out of 130 endemic countries were able to reach the 75% target goal; and 2) less than 77 million school-aged children (of the total 878 million at risk) were reached which means that only 8.78% of at-risk children are being treated for hookworm infection. While there is progress being made, these numbers also remind us of how much work is still to be done.

School-based mass deworming programs have been the most popular strategy to address the issue of hookworm infection in children. School-based programs are extremely cost effective as schools already have an available, extensive, and sustained infrastructure with a skilled workforce that has a close relationship with the community. With little training from a local health system, teachers can easily administer the drugs which often cost less than US$0.50 per child per year.

Recently, many people have begun to question if the school-based programs are necessarily the most effective approach. An important concern with school-based programs is that they often do not reach children who do not attend school, thus ignoring a large amount of at-risk children. A 2008 study by Massa et al. continued the debate regarding school-based programs. They examined the effects of community-directed treatments versus school-based treatments in the Tanga Region of Tanzania. A major conclusion was that the mean infection intensity of hookworm was significantly lower in the villages employing the community-directed treatment approach than the school-based approach. The community-directed treatment model used in this specific study allowed villagers to take control of the child's treatment by having villagers select their own community drug distributors to administer the antihelminthic drugs. Additionally, villagers organized and implemented their own methods for distributing the drugs to all children. The positive results associated with this new model highlight the need for large-scale community involvement in deworming campaigns.

Many mass deworming programs also combine their efforts with a public health education. These health education programs often stress important preventative techniques such as: washing your hands before eating, and staying away from water/areas contaminated by human faeces. These programs may also stress that shoes must be worn, however these come with their own health risks and may not be effective Shoe wearing patterns in towns and villages across the globe are determined by cultural beliefs, and the levels of education within that society. The wearing of shoes will prevent the entry of hookworm infections from the surrounding soils into tender skin regions; such as areas between the toes

Historical examples, such as the hookworm campaigns in Mississippi and Florida from 1943 to 1947 have shown that the primary cause of Hookworm is poor sanitation, which can be solved by building and maintaining outhouses. But while these may seem like simple tasks, they raise important public health challenges. The fact is that most infected populations are from poverty-stricken areas with very poor sanitation. Thus, it is most likely that at-risk children do not have access to clean water to wash their hands and live in environments with no proper sanitation infrastructure. Health education, therefore, must address preventive measures in ways that are both feasible and sustainable in the context of resource-limited settings.

Evaluation of numerous public health interventions have generally shown that improvement in each individual component ordinarily attributed to poverty (for example, sanitation, health education and underlying nutrition status) often have minimal impact on transmission. For example, one study found that the introduction of latrines into a resource-limited community only reduced the prevalence of hookworm by four percent. However, another study in Salvador, Brazil found that improved drainage and sewerage had a significant impact (p<0.0001) on the prevalence of hookworm but no impact at all on the intensity of hookworm. This seems to suggest that environmental control alone has a limited but incomplete effect on the transmission of hookworm. It is imperative, therefore, that more research be performed to understand the efficacy and sustainability of integrated programs that combine numerous preventive methods including education, sanitation, and treatment.