Some Neglected Diseases Could be Eliminated in the Americas, PAHO Paper Says

Neglected Diseases: What are they? What is the situation in the Americas? Neglected diseases are a group of parasitic and other infectious diseases that are generally characterized by historically low investment by the pharmaceutical sector and that mainly affect the poorest segments of society. Among these neglected diseases are lymphatic filariasis, onchocerciasis, intestinal helminthiasis, schistosomiasis, and leishmaniasis:

• Soil-transmitted helminths (STHs, or geohelminths): PAHO/WHO estimates that 20–30% of all Latin Americans are infected with intestinal helminths (worms), while the figures in slums often reach 50% and even go up to 95% in some Amerindian tribes.

• Schistosomiasis (Schistoma mansoni) still affects at least eight countries in the Region, with Brazil carrying the largest burden with at least 2.5 million people estimated to be infected and 6 million at risk.

• Lymphatic filariasis (filarial elephantitis) affects over half a million people in the Region with up to 6–8 million at risk (conservatively), principally in Haiti but also in Guyana, Dominican Republic, and northeastern Brazil.

• Onchocerciasis (river blindness) puts about half a million people at risk in the Region. Its most problematic focus encompasses an extensive region of remote communities on the border of southern Venezuela with northern Brazil.

• Leishmaniasis: Both types (cutaneous and visceral) are a growing problem in rural and peri-urban areas in many countries of the Region, with about 35,000 total cases reported in Brazil alone in 2003. However, under-reporting or lack of reporting is common in the rural and peri-urban marginal areas of the Region where these diseases are usually found.

Prevention, Control and/or Elimination Programs: Global elimination or control programs exist for geohelminths, schistosomiasis, onchocerciasis, and lymphatic filariasis; but global resources are scarce. There are WHO and PAHO resolutions for the elimination of onchocerciasis and lymphatic filariasis as public-health problems, and an initiative is underway to address these in an integrated manner as “neglected diseases”, along with geohelminths, schistosomiasis, and other tropical diseases. To interrupt transmission of onchocerciasis, treatment coverage of no less than 85% must be maintained over a period of 12 to 14 years, while treatment coverage above 80% over a period of five years is critical to interrupting the transmission of lymphatic filariasis in endemic countries.

There has been steady progress in achieving these goals. However, program sustainability depends on political will; and significant advocacy is required.

Geohelminthiasis and schistosomiasis are serious public health problems primarily affecting the school-age population and women of childbearing age, as well as adolescents and young working adults. To address this disease burden, at least 75% of school-age children living in areas at risk for geohelminths and schistosomiasis will require access to regular chemotherapy by 2010, as identified in World Health Assembly (WHA) Resolution 54.19 (2001); where the two diseases overlap, combined treatment is recommended by WHO guidelines, along with improved water and sanitation and health education.

Surveillance and outbreak investigation, as well as prevention and control programs for leishmaniasis, need strengthening in some countries.

A multi-disease and integrated approach to management of these neglected diseases is desirable due to the synergies, logistical efficiencies, and potential cost-savings to be realized in both prevention activities and case management (patient care). Cost-effectiveness data need to be developed for both single- and multi-disease interventions to assist in evidence-based decision-making.

Formulating Strategies and Providing Technical Cooperation: This program is formulating integrated, multidisease-, interprogrammatic-, and intersectoral-based strategies for disease prevention, control and/or elimination, as well as incorporating cost-effectiveness analysis—all based in evidence and with a clear vision towards fulfillment of the Millennium Development Goals MDGs and the development of a neglected diseases agenda. PAHO actively promotes the formulation of national plans, policies and strategies towards prevention, control and/or elimination of neglected communicable diseases; provides technical cooperation to countries with an emphasis on capacity-building of national institutions; and promotes cooperation among and between countries in the Region.

• Bartonellosis (Bartonella bacilliformis)
• Buruli ulcer (Mycobacterium ulcerans)
• Congenital Syphilis / Yaws / Pinta complex (Treponema pallidum subspp.; under discussion); the endemic (non-venereal) treponematoses are yaws (T. pallidum subsp. pertenue), endemic syphilis (T. pallidum subsp. endemicum) and pinta (T. carateum).
• Leprosy (Hansen's disease) (Mycobacterium leprae) Leptospirosis (Leptospira spp.)
• Plague (Yersinia pestis)
• Trachoma (Chlamydia trachomatis)

• Chagas Disease / American Trypanosomiasis (Trypanosoma cruzi)
• Leishmaniasis
  • American Cutaneous Leishmaniasis (ACL) (Leishmania braziliensis complex)
  • Visceral leishmaniasis (Leishmania donovani complex, including L. chagasi in the Americas)

• Enterobiasis / pinworms (Enterobius vermicularis)
• Geohelminth infections (soil-transmitted helminthiasis/STH), principally caused by Ascaris lumbricoides; Trichuris trichiura; hookworms (Ancyclostoma spp., Necator americanus, i.e. the uncinarias)
• Lymphatic filariasis / filariasis / elephantiasis (Wuchereria bancrofti)
• Onchocerciasis / River blindness (Onchocerca volvulus)
• Toxocariasis / visceral larva migrans (Toxocara canis)
• Trichinosis (Trichinella spiralis)

• Fascioliasis (Fasciola hepatica)
• Paragonimosis (Paragonimus westermani): see above Parasitic Trematodes, flatworms
• Schistosomiasis (Schistosoma mansoni)

• Cysticercosis / Taeniasis (esp. Taenia solium)
• Echinococcosis / Hydatid cyst (Echinococcus granulosus)
• Hymenolepsis (Hymenolepis nana)

• Superficial mycoses (Tinea and other fungal infections)
• Tunga flea, Sarcoptes mite, myiasis from fly larvae, head and body lice, ticks

• Hantavirus
• Viral Hemorrhagic diseases (other than dengue hemorrhagic fever / DHF)