Pan American Health Organization

Health Status of the Population

Neglected infectious diseases (NID)

In 2008, of the total estimated global burden of disease-56.6 million disability-adjusted life years (DALYs)-caused by neglected tropical diseases (known as neglected infectious diseases in the Americas), 8.8% occurred in Latin America and the Caribbean (LAC) (). This is more than the combined percentages of the regional burden of disease caused by HIV/AIDS, malaria, and tuberculosis.

This burden of disease is related to poverty and income inequality. In LAC, 24.3%, or about 153 million people, live in total poverty, defined as less than US $4 a day, in 2013. Of those, 11.5%, or about 72.5 million people, live in extreme poverty (less than US $2.50 a day) (). In 2015, 6% of the estimated 630 million people in LAC lacked access to safe drinking water (3% of the urban population and 17% of the rural population), and 17% lacked access to proper sanitation facilities (12% urban and 37% rural) ().

These diseases can be prevented and controlled; they can also be eliminated if health services have and use the proper tools and resources, have a commitment from their governments, and have support from partners and donors.

Many neglected infectious diseases are on the way to being eliminated: lymphatic filariasis, onchocerciasis, schistosomiasis, Chagas disease, leprosy, and trachoma. Others can be prevented or controlled, and WHO recommends several strategies and interventions to do so (). Progress toward controlling and eliminating neglected infectious diseases in the Americas is depicted in Table 1.

An estimated 6 million people in the Region have Chagas disease (down from 30 million in 1990); there are 30,000 annual cases of vectorial transmission (down from 700,000 cases in 1990) and 8,000 cases of vertical transmission. Presently, approximately 70 million persons live at risk of contracting Chagas disease (compared to 120 million in 1990) (). Annual patient care costs are estimated at US$ 627 million, and 806,170 annual DALYs ().

Despite its prevalence, there are gaps in care for Chagas patients. For example, only 1% of people infected with T. cruzi, the parasite that causes Chagas disease, receive timely diagnosis and treatment. The reasons for this are that Chagas is a “silent disease” whose victims are often unaware they have the disease (especially in rural populations); there is a lack of knowledge among health care personnel; and because people often lack access to care ().

There were originally 13 documented onchocerciasis foci in six countries-Brazil, Colombia, Ecuador, Guatemala, Mexico, and Venezuela-with an at-risk population of approximately 568,000 people (). However, due to the success of elimination programs in Colombia, Ecuador, Guatemala, and Mexico (), the current at-risk population in the Americas is now 29,500 people, just 5% of the original at-risk population. This population lives in two active foci: the Amazonas focus in Brazil and the Southern focus in Venezuela. Together, the foci form the Yanomami area, where there are enormous challenges that include geographical barriers and social and cultural elements that make programs to eliminate onchocerciasis difficult. Recent evidence suggests that onchocerciasis transmission has been interrupted in 70% of Venezuela’s Southern focus ().

It is estimated that around 12 million people are living in areas of four countries in the Region where lymphatic filariasis is endemic (Brazil, Dominican Republic, Guyana, and Haiti) (). Mass drug administration of diethylcarbamazine (DEC) and albendazole to the entire population has been implemented in all endemic areas in the Region, with a variable degree of coverage depending on the country (), and sustained progress has been made toward eliminating lymphatic filariasis. In 2011, WHO classified Costa Rica, Suriname, and Trinidad and Tobago as non-endemic. Transmission has been eliminated in several states in Brazil and in most of the metropolitan area of Recife. Interruption of transmission has been demonstrated in the most important transmission foci in the Dominican Republic, with one active disease focus remaining. Mass drug administration has achieved over 65% coverage in endemic areas of Haiti in recent years and there is evidence of interruption of transmission in areas inhabited by 3.1 million of the estimated 11 million people who are at risk. Guyana mass drug administration activities were restarted in 2012.

An estimated 25 million people are at risk of contracting schistosomiasis in the Americas; 90% of them are in Brazil. It is estimated that 1.6 million school-age children need preventive pharmacological treatment (with praziquantel), primarily in Brazil and Venezuela (). The overall prevalence of schistosomiasis in Brazil has been reduced, mostly due to major investments in basic sanitation and safe water supply, improvements in income levels and quality of life, and the availability of praziquantel, which is now produced nationally in Brazil. Available evidence suggests that transmission of schistosomiasis has been interrupted in Antigua and Barbuda, Dominican Republic, Guadeloupe, Martinique, Montserrat, Puerto Rico, Saint Lucia, and Suriname; however, this information needs to be verified.

In 2014, PAHO/WHO estimated that 46 million children in the Region were at risk of soil-transmitted helminthiases (STH); 58% of them are in 3 countries (Brazil, Colombia, and Mexico) of the 24 affected, and 36% are in 7 other countries (Bolivia, Dominican Republic, Guatemala, Haiti, Honduras, Nicaragua, and Peru). More than 5 million preschool-age children and 19.2 million school-age children in need of preventive chemotherapy were treated, providing regional coverage of 38.7% and 56.7%, respectively. The target of at least 75% national coverage was reached in 7 countries. However, approximately 11.7 million children-19% of school-age children and 36% of preschool-age children-who are at risk of soil-transmitted helminth infection still need to be dewormed ().

Trachoma is the leading cause of preventable blindness worldwide (). Considerable progress has been made toward eliminating trachoma as a public health problem in the Americas, setting the stage for the possibility that this Region will be the first to reach elimination goals. However, about 11 million people remain at risk of trachoma in the Americas (). There is evidence of trachoma in four countries: in Brazil (in about 600 municipalities); in Colombia (where a focus of trachoma was recently detected in indigenous communities in the department of Vaupés); in Guatemala (in the department of Sololá); and in Mexico (in the state of Chiapas) (). In 2016, Mexico requested that PAHO/WHO validate that it had eliminated trachoma as a public health problem ().

Annually, there are an estimated 56,000 new cases of leishmaniasis in the Americas (). For the period 2005-2013, DALYs decreased worldwide (), yet there was a 36% increase in the clinically important forms of mucocutaneous leishmaniasis and 8.7% increase in visceral leishmaniasis in the Americas (). However, this increase may be due to improved surveillance efforts.

Leishmaniasis is endemic in 18 countries in the Region; 16 countries reported data from 2012 to WHO (). The cutaneous form occurs in 70.5% of men, and nearly 2,000 cases have forms that can cause deformities. Visceral leishmaniasis is a severe form with a lethality rate of 6.48%; 43% of cases are in children under 10. Higher-risk groups are children under the age of 1 and adults over 50.

Cystic echinococcosis is endemic in Argentina, southern Brazil, Chile, Peru, and Uruguay. These countries constitute what it is known as the Regional Initiative for the Control of Cystic Echinococcosis. Other countries in the southern part of the region may be affected but they do not report to the initiative. From 2009 to 2014, five countries reported nearly 5,000 new cases of cystic echinococcosis diagnosed each year. The average case fatality rate was 2.9%, which suggests that cystic echinococcosis led to approximately 880 deaths in the region during the 6-year period. On average, cystic echinococcosis patients that required secondary or tertiary care spent 10.6 days in a hospital, leading to a significant burden on the countries’ health systems. Additionally, the proportion of new cases (15%) in children younger than 15 suggests ongoing transmission, and the data show that cystic echinococcosis is not under control in the Region. Nevertheless, the long-standing implementation of national and local control programs in three of the countries has achieved reductions in some of the aforementioned indicators ().

Table 1. Progress update in selected NIDs

Chagas disease Seventeen endemic countries have interrupted household vector-borne transmission of T. cruzi by the main vector species in all or part of their territory, and all 21 endemic countries have established universal screening of blood donors for Chagas in national blood banks. Annual incidence and prevalence has decreased as a result of prevention and control measures and overall improvements in the quality of life.
Onchocerciasis Colombia, Ecuador, Guatemala, and Mexico are the first four countries in the world where WHO verified the elimination of onchocerciasis. In addition, transmission in Venezuela has been eliminated in the North-Central focus and interrupted in the North- Eastern focus. The Yanomami area is the last remaining active transmission area in the Americas. Strengthening the cooperation between Brazil and Venezuela in border areas is key to intensifying efforts toward regional elimination.
Lymphatic filariasis Lymphatic filariasis has been eliminated from Costa Rica, Suriname, and Trinidad and Tobago, and significant progress has been made toward elimination in three of the four remaining countries with active transmission: Brazil, Dominican Republic, and Haiti.
Schistosomiasis There is evidence of elimination of schistosomiasis from the Caribbean countries and territories where it was formerly endemic, such as Antigua and Barbuda, Guadeloupe, Martinique, and Montserrat. Saint Lucia and Suriname are close to interrupting transmission, but there is still active transmission in Brazil and Venezuela.
Soil-transmitted helminthiases The numbers of at-risk preschool and school-age children treated for control of soil-transmitted helminth infections have grown as countries assume greater responsibility in tackling this threat to child health and physical and cognitive development. However, additional efforts are needed to achieve optimal, sustained coverage; deworming programs are still a challenge, and efforts need to be expanded to other at-risk groups such as women of childbearing age.
Trachoma In 2016, Mexico requested WHO to validate the elimination of trachoma as a public health problem. Although until 2015 in the Americas there was no evidence of additional foci in countries other than the four known endemic ones, the occurrence of trachoma needs to be ruled out in population groups living in poverty where inadequate access to services such as water, basic sanitation, health, hygiene, and education puts them at risk, and in areas bordering known foci in the Amazon region.
Leishmaniasis Endemic countries set targets to reduce the incidence from visceral leishmaniasis and mortality from visceral and skin/mucosal leishmaniasis as well as proportion of cases of cutaneous leishmaniasis in children younger than 10.

References

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Reference/Note:

Regional Office for the Americas of the World Health Organization
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