SCI Foundation is now Unlimit Health. Learn more about what the change means for our ongoing efforts to eliminate neglected tropical diseases


How do people become infected by parasitic worm infections?

Parasitic worm infections have complex life cycles and affect people without access to clean water and sanitation. For further information about how people become infected, see the links below:

Intestinal worm infections

How are you supporting sustainability?

We address both the sustainability of the health systems and services we support, as well as the sustainability of the outcomes achieved through country-driven disease control and elimination programmes.

In terms of system sustainability, we share knowledge and expertise with governments in support of their programmes from the outset. For this reason, we do not have country offices but have regular contact with countries to provide strategic support as needed. We help strengthen systems and processes, so that they are dynamic, responsive and deliver results, reducing any reliance on external input over time. In this way, we ensure that donations are used as effectively as possible.

To sustain the impact of treatments, we’ve adopted a comprehensive approach that goes beyond treatments to address environmental and behavioural transmission and exposure factors, and increase access to all basic services including healthcare, water, sanitation and education.

Do you only support treatments for children?

Anyone can become infected with parasitic worm infections and we support programmes that aim to treat all individuals at risk of infection according to the guidelines of the World Health Organization. However, the majority of programmes focus on the treatment of school-age children (5-14 years old) to improve their opportunities of growth and learning, reduce the development of severe complications, and due to the ease of distributing treatment in schools. Other high-risk groups – children under 5, pregnant women and adults living in areas where the disease burden is high – are also recommended to be treated. We will support treatment to other age groups if drugs are available and it is part of the country government’s national treatment strategy.

We are also working as part of the Pediatric Praziquantel Consortium to develop an appropriate drug formulation to treat children under 5 years of age.

How often is treatment given?

Every country programme is tailored to meet the specific population needs and how often treatment is given is based on the level of disease, i.e. the prevalence of infection (which is the proportion of the population infected). This level of disease is determined through using existing information, data and frequently by carrying out mapping surveys.

See the WHO Treatment Guidelines that are used to inform country treatment strategies based on the prevalence of infection.

Will treatment be enough to eliminate parasitic worm infections?

Treatment is very effective at reducing levels of parasitic worm infections. In fact, the programme we support can reduce parasitic worm infection levels by 60% after just one round of treatment. (Average result demonstrated for all country programmes where data are available. For every treatment provided against schistosomiasis, treatments are also offered against intestinal worm infections where both diseases are present.)

However, multiple approaches will be needed to eliminate these diseases. Our How We Work page details how we intend to do this.

Why is treatment given repeatedly?

Treatment is safe and effective. In the absence of vaccines, or high coverage of access and availability to safely managed drinking water, sanitation and hygiene, treatment is the best option currently available to reduce parasitic worm infections in populations. (Although a number of candidate vaccines are currently being tested in clinical trials, commercially available vaccines are a long way off.)

Treatment is given repeatedly for a number of reasons:

  • It is only effective against mature adult parasite worms. Therefore, any immature worms in the body will develop to maturity in the weeks following treatment.
  • Treatment does not prevent re-infection. Re-exposure to parasites is common and people will often be re-infected in areas where the disease is present. For example, if fishermen or bathing children come into contact with contaminated water.
  • By treating regularly, it reduces the number of parasitic worms in the body, lowering the number of eggs produced and the significant internal damage the eggs cause.
  • Treatment during a ‘mass drug administration’ programme – where millions of people are treated in a short space of time (usually within a week) – acts to kill a large number of adult worms in a population and in doing so, reduces the chances, or transmission, of infection. This is due to fewer adult worms being available to lay eggs that sustain transmission.

Please see how schistosomiasis and intestinal worm infections are transmitted for further information.

How is cost per treatment calculated?

The formula that we use for cost per treatment is Total Costs / Total Treatments Over Each Financial Year. For us, the most important breakdowns of cost per treatment are what we term:

Cost per delivery of treatment

The cost per delivery of treatment i.e., all the costs that go into the implementation of treating the individual infected or at-risk within in a country / total treatment within a country. These data help us to understand what funds are being allocated and expended in each country, each year and broken down by input type (per diems, fuel, etc.) and activity type (training, sensitisation, reporting, etc.). When analysing these costs on an annual basis, we observe variations between countries and also within countries across years.

These variations in cost per delivery can be explained by factors that can be expected. These include: geographic dispersion of targeted populations; the numbers targeted and treated at school and in the community; the cost and frequency of training teachers and community distributors; or factors which cannot be predicted such as fuel costs, exchange rates, and currency values over time.

The cost per delivery of treatment is critical for us and our partner countries to examine, in detail, how crucial funds from donors are being used, that there is accountability and transparency in how they have been spent and to inform annual budgets and predict effective and efficient spend for the next financial year.

Total cost per treatment

Our use of total cost per treatment is total costs (total cost per delivery of treatment in all countries, total central costs (i.e. Unlimit Health) for supporting country implementation, overheads / total treatments in all countries.

As with the annual fluctuations in the country cost per delivery of treatment, there are more minor annual fluctuations in the total cost per treatment due to the former costs, the procurement of praziquantel and central costs. However, the total cost per treatment has remained within the range of £0.31 – £0.35 for multiple years which is the reason for the message “£1 treats 3 individuals” in our advocacy materials.

Is there any clinically significant drug resistance?

Some tolerance has been reported for praziquantel (the medicine used to treat schistosomiasis), but no true resistance. We believe that resistance to praziquantel and albendazole/mebendazole (the medicine used to treat intestinal worm infections) is unlikely due to their mode of action.

Who actually delivers treatments?

All programmes against parasitic worm infections are owned by country governments. Our team act as independent advisors to support programmes as-needed, but do not deliver treatments. Treatments are usually delivered by school teachers, community drug distributors or health workers, who are trained by the programme, in the ministry of health and/or education. All drug distributors live and work in the areas where they are providing treatment, and are often selected by the communities themselves.

Where does my money go as an individual donor?

Funds received from individuals are used according to our allocation criteria and to ensure sustainability of programmes. For more information, please see How Your Money Is Spent.

How are drugs donated?

All drugs used in the programmes we support are generously donated by three pharmaceutical companies. Merck KGaA donates the drug praziquantel, used to treat schistosomiasis. GSK donates albendazole and Johnson & Johnson donates mebendazole – both drugs are used to treat intestinal worm infections.

We work with country programmes to calculate the number of drugs they need each year and complete their request to the World Health Organization. The World Health Organization coordinates the processing of applications from all countries and allocates the donated drugs accordingly, which are then shipped from the pharmaceutical companies to each country.

I make a regular donation to Unlimit Health. Do I need to amend my direct debit/standing order now that you are Unlimit Health?

No, you do not need to amend your direct debit/standing order. Your regular donation will continue as normal. It should now appear in your bank statements as a payment to Unlimit Health. If you have any questions about making donations, please contact

What are you doing to prevent parasitic infections from occurring in the first place?

The transmission of parasitic infections such as soil-transmitted helminths (STH) and schistosomiasis is fundamentally linked to environmental conditions, such as inadequate provision of water and sanitation services, and to other aspects such social structures that put certain people at risk of infections, as well as individual and community behaviours. We understand the need for a comprehensive intervention package for the prevention of parasitic worm infections. We can play an important role in both enhancing the effectiveness of environmental interventions for disease prevention, and the targeting of such interventions to high-prevalence areas. Read more

Does Unlimit Health still support deworming treatment?

Yes. Supporting the delivery of deworming treatment remains a key part of our work to end parasitic disease.

We continue to support our partner governments to deliver millions of deworming treatments every year.

We also support our partners to expand their treatment programmes. Broadening access to good health requires broadening access to treatment for parasitic disease to people who currently miss out – for example, younger children, women of reproductive age, and other at-risk adults.

In addition, we aim to support work to target treatment more precisely on areas of greatest need, making treatment and elimination efforts more efficient, and their impact more sustainable.

Why does Unlimit Health support stronger health systems?

To achieve elimination of parasitic disease, it is necessary to address the conditions that create the risk of infection.

These conditions are closely related to poverty and health inequity. Parasitic diseases thrive in communities which lack access to basic services such as clean water and sanitation, and effective, well-resourced and affordable healthcare services.

This is why our new strategy emphasizes support for health systems that provide the full range of quality health services – including prevention of disease transmission, treatment against, and care for parasitic disease and its consequences – for everyone who needs them.

What is ‘country ownership’ and why is it important?

Country ownership is when health system priorities, and their necessary resourcing, are controlled by endemic countries themselves.  Resilient health systems can only be built if they are country-owned because endemic countries are best placed to understand the needs and priorities of their own populations. This is why, in line with the targets and goals set out under the Sustainable Development Agenda, and by the World Health Organization (WHO), our new strategy emphasizes our support for country ownership of health programmes. It is why we do all we can to put our expertise at the service of our endemic country colleagues.

Why did you decide to rebrand?

Our 2023-28 strategy made us reflect on how we communicate about who we are. In doing so, we realised our brand no longer represented our work, nor spoke to our audiences or reflected our new ambition to end parasitic disease alongside our partners. We needed to align our new strategy to the current global health and human development context. Our new brand now speaks to that.

What is your strategy for tackling parasitic diseases?

We launched an ambitious new five-year strategy in 2023. It builds on the need for system resilience and equity at the heart of development efforts, and the shift in emphasis away from a funder-led agenda to one driven by local ownership and sustainability considerations.

The strategy is aligned with the three pillars of the World Health Organization’s (WHO) road map for neglected tropical diseases (NTDs), enabling a stronger focus on programmatic action, cross-cutting approaches, and country ownership. It signifies a paradigm shift from intervention delivery to health equity and health system strengthening. You can read our new strategy here.