Neglected tropical diseases (NTDs)

Neglected tropical diseases are diverse group of tropical diseases that affect more than 1 billion people including 500 million children in 149 tropical and subtropical countries globally. NTDs are endemic and bacterial and parasitic diseases that affect mainly the world’s poorest communities with inadequate sanitation and absence of clean water. The 7 most common NTDs are found in low and middle-income countries of Asia, Africa and Latin America. The examples of some neglected tropical diseases are as follows:

• Chagas disease/American Trypanosomiasis: Named after Brazilian doctor Carlos Chagas this disease is caused by the unicellular protozoan parasite Trypanosoma cruzi and mainly found in the rural areas of Latin America. This parasite is transmitted to human blood  by triatomine bugs and result in cardiomyopathy and dysrhythmias.

• Buruli ulcer: This disease is usually found in the tropical areas of Africa and Australia and caused by the bacteria Myobacteria ulceran which affects the skin and bone. This bacteria produces plasmid-encoded toxin mycolactone that diffuses into subcutaneous fat and causes progressive necrosis [1].

• Dengue: The most common tropical and subtropical disease that affects 400 million people every year is caused by the viruses transmitted mainly by Aedes mosquitoes. Dengue virus is a small single-stranded RNA virus that has four distinct serotype which are transmitted to humans through the bite of infected Aedes mosquitoes mainly A. aegypti.

• Cysticercosis: A parasitic infection caused by Taenia solium that infects brain muscle and other tissues.

• Echinococcosis: A parasitic infection caused by the small tapeworm Echinococcus granulosus (Cystic Echinococcosis) and Echinococcus multilocularis (Alveolar Echinococcosis/AE) that result in infiltrative liver lesions.

• Onchocerciasis/River blindness: An infection caused by the worm O. volvulus and transmitted by black fly (Simulium) and mainly found in Africa resulting in skin lesions and blindness. Ivermectin drug treatment is the most effective method of control of this disease.

Currently there are various researches going on to prevent and control NTDs. Metabolomics study identified small molecules biomarkers (SMBs) in acute phase clinical specimens (blood serum) that differentiate dengue disease outcomes [2]. These metabolites (SMBs) also provide the insight of metabolic pathways, pathogenic and immunologic mechanism associated with dengue  disease. Medical research on AE  suggests that serial endoscopic balloon dilation and stenting combined with benzimidazole treatment can re-establish and maintain biliary duct patency for many years in AE patients [3]. Currently 13 leading pharmaceutical companies, global health organizations, donor and endemic country governments are partnered with World Health Organization to control, eliminate and reduce the global burden of  NTDs.  

References:

1. https://bmb.oxfordjournals.org/content/early/2009/12/10/bmb.ldp046.full
2. http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0004449#sec022
3. http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0004278#sec012