Eliminating neglected tropical diseases

By Francisca Mutapi:

A major health challenge of our time is when drugs no longer work to treat infections. This happens when the agents that cause infections – they may be bacteria, viruses or fungi – become resistant to the drugs.

Antimicrobials are a broad range of medications that act on microbes – like bacteria, fungi, viruses or parasites. Antibiotics, for instance, are one type of antimicrobial working against bacteria.

Resistance to antimicrobial drugs therefore makes it difficult to treat and prevent a wide range of infections.

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Antibiotic resistance compromises public health programmes, such as TB treatments.

It can also compromise other medical interventions where treatment is needed to prevent infection, like surgery, caesarean sections or cancer treatment.

The main causes of antimicrobial resistance are the misuse and overuse of antimicrobials in humans, animals and plants.

Antimicrobial resistance leads to more deaths and illness in Africa compared to anywhere else.

The continent recorded 21 percent of the global antimicrobial resistance related deaths in 2019. In that year, over 1.05 million deaths in Africa were associated with antimicrobial resistance. This poses an exceptional health threat.

Worryingly, antimicrobial resistance related deaths are predicted to increase globally. The trend is already being observed in Africa.

For example, the latest data shows that the share of E. coli infections resistant to cephalosporins (the antibiotic used to treat them) is rising.

To change this, it is necessary to reduce the burden of diseases that require antimicrobial treatment.

One group of infectious diseases prevalent in Africa are the neglected tropical diseases (NTDs). There are already effective tools to prevent and even eliminate them.

But every year, millions of people are infected and treated for them using antimicrobials. This increases the risk of spreading resistance.

Having been involved in the design and implementation of large-scale neglected tropical diseases control programmes, I argue for a push to eliminate these diseases.

This must be done through integrated approaches, including preventive medicine, water and sanitation, and controlling the agents that spread the diseases.

Even countries where neglected tropical diseases are not common should make this push, as part of global health security.

Controlling neglected tropical diseases

Neglected tropical diseases are a group of 21 diverse conditions capable of causing long term health and economic challenges.

They are caused by a variety of pathogens including worms, bacteria, fungi and viruses. Of these diseases, six are treated with antibiotics: buruli ulcer, leishmaniasis, leprosy, onchocerciasis, trachoma and yaws.

Globally, millions of people with neglected tropical diseases are treated with antimicrobials every year.

One of the most effective public health approaches for controlling neglected tropical diseases is preventative chemotherapy, which involves mass drug administration, where people are treated without diagnosis.

Nonetheless, it is not sustainable, both in terms of cost and because it increases the risk of antimicrobial resistance.

However, preventative chemotherapy is a necessary and effective tool for reducing infection and disease. Since 2012, over 600 million people have been cured of neglected tropical disease infection this way.

An example of this is Zimbabwe’s control programme for schistosomiasis (an acute disease caused by parasitic worms), which I have been involved with.

Preventative chemotherapy was administered to about five million children every year between 2012 and 2019. Infection levels were reduced from 32 percent to just under two percent in children aged six-15.

The latest World Health Organisation report from 2022 indicated that just under 1.7 billion people globally required preventative chemotherapy. Of these just under 600 million are in Africa.

Another risk for an increase in antimicrobial resistance is that the antibiotics used to treat neglected tropical diseases are also used to treat other infections.

For example, azithromycin (for treating trachoma and yaws) is used also to treat other bacterial infections including bronchitis, pneumonia and sexually transmitted diseases.

Already, of the six neglected tropical diseases that are treated with antibiotics, five have documented drug resistance. This trend will only increase.

It is therefore vital that neglected tropical diseases are eliminated so that fewer antibiotics and antimicrobials are used. This also protects people from other dangerous infections.

Ready-made tools

The good news is that the tools to eliminate neglected tropical diseases already exist.

Within the past decade, 51 countries have eliminated at least one neglected tropical disease. Underlying these successes are the use of multiple tools, cross-sectoral strategies and sustained efforts to prevent and treat infections.

In the case of diseases which are transmitted by animals or insects (vectors), it is about controlling the vector. For instance, killing the flies that transmit onchocerciasis parasites or snail hosts for schistosomiasis.

Similarly, provision of safe water and sanitation facilities is critical for disease elimination. For example, the organisms that cause some diseases spend some stages of their life in faeces (poop).

So, when faeces are poorly disposed of, they can contaminate the environment and the disease can be passed on.

The World Health Organisation has set a target of 100 countries eliminating at least one neglected tropical disease by 2030.

This would be a massive health and economic win for countries where the diseases are prevalent.

It will also lead to a reduction in antimicrobial use – which is a vital global health goal.