3 Things Pharmacists Should Know About Neglected Tropical Diseases

Since many neglected tropical diseases never appear in pharmacy school textbooks, here are some things you need to know about them.

The World Health Organization classifies 17 diseases as neglected tropical diseases (NTDs), which are a diverse group of communicable diseases that affect more than 1 billion individuals in 149 countries.1

NTDs disproportionately affect those living in poverty, who often have inadequate sanitation and come in close contact with animals and insects that can transmit disease.

Since many NTDs never appear in pharmacy school textbooks, here are 3 things you need to know about them:

1. Tropical Does Not Mean Exotic

Just because these communicable diseases are most often transmitted in the tropics and subtropics doesn’t mean they are only encountered there. Many NTDs affect patients in the United States, Canada, and Europe, particularly immigrants from endemic regions.2

One example is Chagas disease, which primarily affects immigrants from Latin America.3

Chagas disease, or American trypanosomiasis, is caused by the protozoan parasite Trypanosoma cruzi and most commonly transmitted by the blood-feeding triatomine bug, though it can also be transmitted through transfusion of contaminated blood, organ transplantation, and congenitally from mother to child.

There is both an acute and chronic phase of the disease. In the chronic phase, patients may develop cardiac complications (eg, arrhythmias and heart failure) and gastrointestinal complications (eg, dilation of the esophagus or colon).

Although approximately 8 million individuals are infected in Latin America, the US Centers for Disease Control and Prevention estimates that at least 300,000 people in the United States have Chagas disease.

If you have a substantial patient population from Mexico, Central America, or South America, you will very likely encounter a patient with undiagnosed or diagnosed Chagas disease at some point.

2. Many NTDs Can Cause Chronic Diseases

A common misconception is that all NTDs resolve after anti-infective treatment. Some NTDs may cause chronic diseases that can lead to lifetime disability. An important example of this is neurocysticercosis, which is a major cause of epilepsy worldwide.4

Neurocysticercosis is an infection of the central nervous system with the tapeworm Taenia solium. In its larval stage, the tapeworm exists as a cyst, where it can cause almost any neurological symptom, the most common of which is seizures.5

Medical treatment typically consists of albendazole and/or praziquantel, which kill the active cysts, and corticosteroids, which help control the inflammatory response to the dying cysts.

Even after treatment, however, symptoms may persist. For example, seizures may remit in some patients, but others may develop epilepsy requiring long-term, if not lifelong, treatment.

3. Better Drugs for NTDs Are Needed, But So Is Better Awareness

Because NTDs disproportionately affect the poorest individuals in the world, there is little opportunity for profit, and hence little commercial interest from the pharmaceutical industry to develop new drugs. Many of the drugs used to treat NTDs lack sufficient empirical evidence, while others can be highly toxic.

But the future is not entirely bleak, thanks to organizations such as Drugs for Neglected Disease Initiative (DNDi).6

DNDi is a non-profit drug research and development organization, working to development new treatments for NTDs. Since 2007, it has brought 6 new treatments to the market.

As we all know, new drugs are not developed overnight. However, as individual health care professionals, what can we do?

The first step is improving our own awareness of NTDs and their impact on our patients. Knowledge is power in pharmacy, so the more we know, the better we can educate patients and other health care providers and manage pharmacotherapy in patients affected by these diseases.

References

1. World Health Organization. Neglected tropical diseases. http://www.who.int/neglected_diseases/diseases/en. Accessed January 8, 2016.

2. Centers for Disease Control and Prevention. Parasites: American trypanosomiasis (also known as Chagas disease). http://www.cdc.gov/parasites/chagas. Accessed January 8, 2016.

3. Romo ML. Need for pharmacist awareness of Chagas disease. Am J Health Syst Pharm. 2014;71:1069-1070.

4. Carpio A, Romo ML. The relationship between neurocysticercosis and epilepsy: an endless debate. Arq Neuropsiquiatr. 2014;72:383-390.

5. Centers for Disease Control and Prevention. Parasites: Cysticercosis. http://www.cdc.gov/parasites/cysticercosis/index.html. Accessed January 8, 2016.

6. Drugs for Neglected Diseases Initiative. DNDi — Best Science for the Most Neglected. http://www.dndi.org. Accessed January 8, 2016.