Commentary by Alpana Marwaha MD PGY-3
Please also see the clinical vignette presented before last week’s grand rounds.
This week, the Department of Medicine Grand Rounds was presented by Dr. Peter Hotez MD, PhD and chair of the Department of Microbiology and Tropical Medicine at GW Medical Center. The talk was entitled, “Combating The Poverty Associated Tropical Diseases.”
There are a staggering 1.4 Billion people living at wages below $ 1.25 per day known as the “The Bottom Billion.” The prevalent Neglected Tropical Diseases (NTDs) affecting these “bottom billion” include Ascariasis, Trichuriasis, Hookworm, Schistosomiasis, Lymphatic Filariasis, Trachoma, Onchocerciasis. While Filariasis can cause disabilities such as disfigurement and loss of limb use, millions of villagers are rendered blind by Trachoma. These diseases also reduce agricultural productivity, have a huge social stigma attached to them and increase maternal morbidity and mortality. Furthermore, they impact child growth and development as children often tend to have the highest worm burden. Thus these diseases that are bred by poverty go on to promote poverty, forming a vicious cycle. When studies calculated DALY’s lost due to these conditions, NTDs stood head to head with Ischemic Heart Diseases at 56 million. Facts like these have made policy makers realize the actual threat and extent of these tropical diseases.
Understanding this, Dr. Hotez went on to explain what has been done to treat and prevent these diseases so far. Initially, this was with preventive chemotherapy and through mass drug administration. Prevalence studies have revealed that people in endemic areas are often poly-parasitized. Thus a solution called the Rapid Impact Package (RIP) was designed and it includes four medications aimed at treating the 7 most common tropical diseases at an affordable price of 50 cents per package. Using these solutions, the United Nations formed a Global Network for Neglected Tropical Diseases Control (GNNTDC) which seeks to coordinate the efforts of seven organizations that fight NTDs. Dr. Hotez has been a motivational force in organizing this movement.
However there were setbacks to the project. Metanalyses showed drug failure of mebendazole to eradicate Hookworm infection, either due to reinfection or through drug resistance (as the hookworm only requires a single point mutation). Therefore, a new initiative was undertaken by Dr. Hotez. He is the Principal Scientist of the Human Hookworm Vaccine Initiative (HHVI), a public-private partnership sponsored by the Sabin Vaccine Institute with major funding from the Bill and Melinda Gates Foundation providing an $18 million hookworm vaccine grant. The Human Hookworm Vaccine will be bivalent, consisting of 2 antigens. One will help the immune system target larval stage hookworm parasites while the other will target adult hookworm (Anti-APR-1). The hookworm larval antigen ASP-2 (ancylostoma secreted protein-2) is identified as the protective antigen linked to reduced risk of heavy hookworm infection. Currently, the vaccine is in Phase 1 clinical trials in Brazil. The HHVI also plan to come up with multivalent Anti-Helminthic vaccine in the future. Lastly, Dr. Hotez talked about the prevalence of tropical diseases in the Unites States, given the increasing migrant population. NTD in the US include trichomoniasis, cysticercosis and even cases of dengue.
In summary, we realize the huge global burden of NTDs, need to control them through chemoprophylaxis and the need for development of innovative and cost effective strategies like the HHVI.