Article No. 4 - Vol. 28, No. 4 - December 2009

Elimination of neglected diseases and other poverty-related infections:

Situation analysis and outline of a strategy

In Latin America and the Caribbean, around 127 million people live in poverty. Neglected diseases – diseases against which there are cost-effective measures but that for various reasons do not receive adequate attention, such as lymphatic filariasis, oncocercosis, Chagas disease or neonatal tetanus - are often restricted to marginalized sections of the population, including the rural poor, slum residents, migrant workers, women, and indigenous people. These groups suffer a higher burden of parasitic and other diseases related to an insufficient access to drinking water, sanitation, adequate housing, education, and a lack of access to health services—for them, neglected diseases are both a cause and a consequence of poverty. Most of them cause chronic conditions that can reduce learning capabilities, productivity, and income earning capacity.

The PAHO Member States have expressed their political commitment to address public health problems that can be eliminated or drastically reduced through the approval of various mandates and resolutions. This commitment is also reflected in PAHO’s Strategic Plan 2008-2012, which proposes fighting the communicable diseases that unduly affect poor and marginalized populations in the Americas.(3) Furthermore, the recently prepared Health Agenda of the Americas, 2008-2017, calls for reducing the burden of certain communicable diseases that disproportionately affect the poor.

The Region of the Americas has had much experience in successfully putting in place elimination and eradication strategies for diseases such as smallpox, polio, and measles. And, thanks to the efforts of Member States, some neglected diseases have come close to being eliminated. A comprehensive approach will be required to address these diseases, ensuring access to existing diagnostic and treatment tools and establishing a multi-sectoral agenda that can address these diseases’ social determinants. To achieve this goal, however, it is necessary to have a political commitment that ensures a greater availability of resources and international support. During PAHO’s 49th Executive Committee, Member States signed a resolution that outlines this commitment in the Region of the Americas. Following are the main points on the situation of neglected diseases and some ideas for possible strategies to reduce and/or eliminate them.

 

Situation analysis and preliminary selection of diseases

A preliminary study that analyzed the situation of 10 selected neglected diseases, which compiled information from secondary sources, found that neglected diseases occur to some degree or another in every Latin American and Caribbean country. The most prevalent are soil transmitted helminthiasis, with an estimated 26 million school-aged children at risk, followed by schistosomiasis (25 million at risk), and lymphatic filariasis (11 million at risk). The study also concluded that there is a considerable amount of available information for most of the neglected diseases, although additional baseline studies that use standardized criteria are still needed. (4) Box 1 shows a summary of the epidemiological situation of these diseases in the Region.

 

Box 1: Epidemiological situation, elimination goals, and primary elimination strategies for selected neglected diseases and other infections related to poverty. (5)

GROUP 1:  Diseases that have a greater potential for being eliminated (with available cost-effective interventions)

Disease

Epidemiological situation

Goals

Primary strategy

Chagas’ disease

There was evidence of transmission in 21 countries of the Americas.

It is estimated that 8 to 9 million people are currently infected.


40,000 new cases of vector-borne transmission per year.

Vector-borne transmission by the main vectors has been interrupted in several countries (Uruguay, Chile, Brazil, and Guatemala) and areas (Argentina and Paraguay).

Most countries in Latin America are close to reaching the goal of implementing screening for Chagas in 100% of their blood banks.

To interrupt domestic vector-borne transmission of T. cruzi (domestic triatomine infestation index of less than 1% and negative seroprevalence in children up to five years of age, with the exception of the minimum represented by cases in children of seropositive mothers).

To interrupt transfusional transmission of T. cruzi (100% blood screening coverage).

To integrate diagnosis of Chagas’ disease in the primary health care system, in order to provide treatment and medical care to all patients for both the acute and chronic phases and to reinforce the supply chain of the existing treatments within countries to scale up access.

To prevent the development of cardiomyopathies and intestinal problems related to Chagas' disease, offering adequate health care to those affected by the various stages of the disease.

To eliminate vectors in the home through chemical control.

Environment management programs.

Information/Education/Communication (IEC).

Screening of blood samples in blood banks to avoid transmission by blood transfusion.

Screening of pregnant women and treatment to avoid congenital transmission.

Good practices on food preparation to avoid oral transmission.

Etiologic treatment of children

Offer medical care to adults with Chagas’ disease.

 

Congenital syphilis

It is estimated that 250,000 cases of congenital syphilis occur each year in the Region.

In a 2006 survey, 14 countries reported the incidence of congenital syphilis in live births, with a range varying from 0.0 cases per 1,000 live births in Cuba to 1.56 in Brazil.

To eliminate congenital syphilis as a public health problem (less than 0.5 cases per 1,000 live births).

Obligatory notification of syphilis and congenital syphilis for pregnant women.

Universal blood screening during the first prenatal visit (<20 weeks,) during the third trimester, during labor, and following stillbirth and abortion/miscarriage.

Timely and adequate treatment for all expectant mothers with syphilis, and the same for spouses and newborns. 

Human rabies transmitted by dogs

The disease has been present in 11 countries in the past 3 years.

Even though the number of human cases is low (16 in 2008) due to country efforts, the number of people who live in risk areas due to rabies in dogs is still high.

The majority of the cases occurred in Haiti and Bolivia.

To eliminate human rabies transmitted by dogs (zero cases reported to the Epidemiological Surveillance System for Rabies (SIRVERA) coordinated by PAHO).

 

Vaccination of 80% of the canine population in endemic areas.

Care given to 100% of the exposed population at risk with post-exposure prophylaxis when indicated.

Epidemiological surveillance.

Education and communication to increase awareness of the risk of rabies.

Leprosy

There are 24 countries where the disease has been present in the last three years.

Only in Brazil did the national prevalence not reach the “elimination as a public health problem” goal of fewer than one case per 10,000 population.

 In 2007, 49,388 cases of leprosy were reported in the Americas, and 42,000 new cases were detected.

In the same year, 3,400 new cases (8% of the total) were detected with grade- 2 disability.

 

To eliminate leprosy as a public health problem (less than 1 case per 10,000 people) from the first sub-national political/administrative levels.

 

 

Intensified surveillance of contacts.

Treatment with timely multi-drug therapy in at least 99% of all patients.

Define the appropriated introduction of chemoprophylaxis.

Early detection of grade-2 disabilities.

 

  • Lymphatic filariasis

The disease is present in Brazil, the Dominican Republic, Guyana, and Haiti.

It is estimated that up to 11 million people are at risk of infection.

 The population most at-risk is in Haiti (90%).

 

To eliminate the disease as a public health problem (less than 1% prevalence of microfilaria in adults in sentinel sites and spot-check sites in the area).

Interrupt its transmission (no children between ages 2 and 4 are antigen-positive).

 To prevent and control disability.  

 

Mass drug administration (MDA) once a year for at least 5 years with coverage of no less than 75% or consumption of diethylcarbamazine (DEC)-fortified table salt in the daily diet.

 

Surveillance of LF morbidity by local health surveillance systems. Morbidity case management.

 Integration/coordination of MDA with others strategies.

Communication strategies and education in schools.

 

Malaria

There are 21 malaria-endemic countries in the Region.

Some countries, such as Paraguay and Argentina, are of low endemicity (fewer than one case per 1,000 population at risk) and have well established foci.

In the Caribbean, only Haiti and the Dominican Republic are considered endemic, reporting approximately 26,000 cases in 2007 (90% in Haiti).

To eliminate malaria in areas where interruption of local transmission is feasible (Argentina, the Dominican Republic, Haiti, Mexico, Paraguay, and Central America).

 Elimination (zero local cases for 3 consecutive years); pre-elimination (slide positivity rate = < 5 % and <1 case / 1,000 population at risk).

 

 

Prevention, surveillance, early detection and containment of epidemics.

Integrated vector management.

Prompt diagnosis and appropriate treatment of cases.

Intensive pharmacovigilance of possible resistance to treatment and use of results in definition of treatment policy.

Strengthening of primary health care and integration of prevention and control efforts with other health programs.

Community participation.

Neonatal tetanus

The disease has been present in lower rates in 16 countries in the past 3 years.

A total of 63 cases were reported in 2007 (38 in Haiti).

It has been eliminated as a public health problem in all Latin American and Caribbean countries except Haiti.

To eliminate the disease as a public health problem (fewer than 1 case per 1,000 newborns per year in a municipality or district).

 

Immunization of women of childbearing age with tetanus toxoid.

Identification of high risk areas.

Adequate surveillance.

Clean delivery and post-delivery practices.

Onchocerciasis

It is estimated that 500,000 people are at risk in the Region.

13 foci exist in Brazil, Colombia, Ecuador, Guatemala, Mexico, and Venezuela.

 In 6 foci, transmission appears to have been interrupted following massive drug administration with a coverage of at least 85% of the eligible population.

 They are currently undergoing a three-year post-treatment surveillance prior to certification of elimination.

To eliminate ocular morbidity and to interrupt transmission.

Mass drug treatment administration at least twice a year in order to reach at least 85% of the eligible population in each endemic area.

Surveillance for signs of ocular morbidity, microfilaria, nodules.

Dermatological care through the primary health care system in areas where skin infection is a problem.

  • Plague

The disease is present in wild foci in 5 countries with sporadic cases: Bolivia (no reported cases during last 10 years), Brazil, Ecuador, Peru and United States.

Currently the number of cases throughout Latin America is low (around 12 cases per year).

Most of the cases reported are in Peru.

Very few are fatal.

The cases usually occur in small rural villages with extreme poverty.

To eliminate as a public health problem (zero mortality cases and avoid domiciliary outbreaks).

Early detection and timely case management.

Surveillance of the wild foci.

Housing and sanitation improvements.

Rodent and vector control.

ntersectoral programs for improvement for storage of crops.

Adequate elimination of agricultural waste.

Extra household installations for farming the “cuyes” (type of guinea pigs used for food consumption).

  • Trachoma

There is evidence of the presence of the disease in Brazil, Guatemala, and Mexico.

Foci have been confirmed in Brazilian border states but no data was found for neighboring countries.

It is estimated that around 50 million people live in areas at-risk and about 7,000 cases have been identified, mostly in Brazil.

To eliminate new cases of blindness caused by trachoma (reduction in the prevalence of trachomatous trichiasis to less than 1 case per 1,000 (general population) and reduction in the prevalence of follicular or inflammatory trachoma (FT and IT) to less than 5% in children aged 1-9 years).

The ”SAFE” strategy is used with the following components:

To prevent blindness through eyelid surgery to correct the inversion or entropy of the upper eyelid and trichiasis.

To reduce the transmission in endemic areas by washing of the face and by using antibiotics.

 

GROUP 2:  Diseases whose prevalence can be drastically reduced (with available cost-effective interventions)

Disease

Epidemiological Situation

Goals

Primary Strategy

Schistosomiasis

The disease is present in: Brazil, Saint Lucia, Suriname, and Venezuela.

Studies are needed to confirm the elimination of previously endemic areas in the Caribbean.

It is estimated that around 25 million people live at risk in the Americas.

Around 1 to 3 million people are estimated to be infected.

 To reduce prevalence and parasite load in high transmission areas to less than 10% prevalence as measured by quantitative egg counts.

Preventive chemotherapy for at least 75% of school-age children that live in at-risk areas, defined by a prevalence over 10% in school-age children.

Improvements of excreta disposal systems and access to drinking water, education.

Soil-transmitted helminthiasis

It is estimated that soil-transmitted helminthiasis is present in all the Region’s countries.

Regional estimates put the number of school-age children at risk of the disease at 26.3 million in Latin America and the Caribbean.

13 of the 14 countries with information available there were one or more areas with prevalence of STH higher than 20%.

To reduce prevalence among school-age children in high risk areas (prevalence >50%) to less than <20% prevalence as measured by quantitative egg count.

Regular administration of preventive chemotherapy/or mass drug administration (MDA) for at least 75% of school-age children at risk, as defined by the countries considering the prevalence. If prevalence of any soil-transmitted helminthiasis infection among school-age children is ≥ 50% (high-risk community), treat all school-age children twice each year. If prevalence of any soil-transmitted helminthiasis infection among at-risk school-age children is ≥ 20% and < 50% (low-risk community), treat all school-age children once each year.

Promoting access to safe water, sanitation and health education, through intersectoral collaboration.

As mentioned before, neglected diseases unduly affect vulnerable populations. And, although not enough gender-sensitive research has been conducted, some studies point out that women suffer a higher burden. Culturally determined distribution of work and duties leave women more exposed to risk factors, resulting in a higher prevalence of the disease among them. Moreover, barriers in access to health care or preventive services and stigma and discrimination that more often affect women result in worse consequences of the disease for women. (6), (7), (8) Clearly, more information is needed on how neglected diseases differentially affect other vulnerable populations.

 

Cost-effectiveness

Cost-effective interventions have been developed and successful control has been achieved for some neglected diseases and other poverty-related diseases. For Chagas’ disease, for example, studies on the efficiency of control methods suggest an internal rate of return of nearly 30% in Brazil and more than 60% in the province of Salta, Argentina; for lymphatic filariasis the cost-effectiveness of three major integrated strategies was estimated in different scenarios with very good results in terms of disability adjusted life years (DALYs) (9) saved.(10)

The per capita health-care cost of neglected disease control is modest in absolute terms and in relation to the per capita total health expenditure.(11) If living conditions are to be improved in the geo-political areas that have been identified as “hot spots” for neglected diseases (priority areas for interventions because of their epidemiological and socioeconomic status) and if these improvements are to be long-lived, it will be necessary to enter into partnerships to address the social determinants of neglected diseases and other diseases related to poverty, such as access to drinking water and sanitation, adequate housing, and education.

 

Definition of diseases and criteria for preliminary selection

The methodology used to determine which diseases could be reduced or eliminated is presented below. Elimination of a disease corresponds to the reduction to zero of the incidence of a given disease in a defined geographic area as a result of deliberate efforts, with continued intervention measures being required.(12) Also, the elimination of a disease as a public health problem means drastically reducing the disease’s burden to a level that is acceptable given the current tools available and the Region’s health situation.  At this level, the prevalence of the disease does not constrain social productivity and community development. Achievable goals have been established for each disease. In this document, both definitions will be used to select the diseases targeted for elimination, according to previous global and regional mandates.

The following criteria were considered in selecting the diseases that could feasibly be eliminated or drastically reduced in the Region: (a) the unfinished agenda—diseases that already had been priority targets for elimination and for which, despite progress made, some areas lagged behind; (b) technical feasibility—including the availability of knowledge and tools for structuring interventions to interrupt or reduce transmission; (c) regional evidence of achievable elimination—existence successful regional experiences in accomplishing elimination at country or sub-national levels; (d) economic criteria—including relatively low unit cost of interventions and demonstrated cost-effectiveness; (e) unequal burden of disease—wherein the more vulnerable populations (such as indigenous and Afro-descendant populations, women, and children who have been historically excluded) suffer from a higher prevalence and social consequences of these diseases, thus perpetuating the cycle of poverty; (f) political relevance—the diseases must be recognized as being of public health importance with a broad international appeal, which could be expressed through existing resolutions approved by the World Health Assembly or PAHO’s Directing Council; (g) best practices—including those utilized in primary health care, well-accepted interventions such as mass preventive chemotherapy and high-coverage vaccination campaigns, integrated approaches for vector-borne diseases, and local projects with community participation to improve health through inter-sectoral action. These examples of best practices have already been developed in the Region and will provide the basis for the scale-up of local and national proposals for disease elimination.

As shown in Box 1, the selected diseases can be divided into two groups: those with greater potential for being eliminated, and those that can be drastically reduced with available tools. The following paragraphs show the diseases in each group.

  • Group 1, diseases that have a greater potential for being eliminated: ‘Chagas’ disease (vector-borne and transfusional transmission, both as a public health problem); congenital syphilis (as a public health problem); lymphatic filariasis (as a public health problem); onchocerciasis; rabies transmitted by dogs; neonatal tetanus (as a public health problem); trachoma (as a public health problem); leprosy (as a public health problem at the national and first subnational level); malaria (elimination in Haiti and the Dominican Republic and in Mexico and Central America); plague (as a public health problem).

  • Group 2, diseases whose burden can be drastically reduced with available tools: schistosomiasis and soil-transmitted helminthiasis.

For other infectious diseases, such as leishmaniasis and leptospirosis, the burden of the disease needs to be further assessed, tools need to be developed, and methods and strategies for achieving cost-effective control need to be established. For these diseases and for others that have epidemiological relevance to some of the Region’s countries, more operational research needs to be conducted, new tools need to be assessed, and surveillance systems need to be improved, mainly in terms of the current technical capacity in the Region’s research centers.

See Box 1 for possible objectives and strategies for each disease.

 

Framework for eliminating neglected diseases and other diseases related to poverty

The public health strategies that are used to eliminate or reduce diseases to acceptable levels go beyond routine control measures. In order to strengthen the efforts against diseases related to poverty as a group, Member States agreed to develop integrated plans under the same framework, while considering the following:

  1. Available plans at the global, Regional, or country level to eliminate or control these diseases.

  2. Available guidelines for the selected diseases to support the countries in achieving the goals of elimination or control.

  3. Available tools such as drugs and diagnostic techniques to support surveillance systems.

  4. Evidence-based decisions for strengthening health surveillance systems, mapping the diseases to identify remaining foci, and identifying overlapping of diseases in geopolitical areas (“hot spots”) for integrated action.

  5. Reducing gaps in tool-ready neglected diseases among areas in the Region.

  6. Ensuring that the necessary resources are available for the primary care system to help reduce inequalities in health.

  7. Pursuing inter-programmatic interventions that integrate the various plans into a comprehensive vision based on the social determinants of each area identified for intervention (“hot spot”); interventions should tackle the factors and mechanisms through which social conditions affect the community’s health and where possible, address them through social and health policies.

  8. Pursuing community participation and intersectoral partnerships: the community, stakeholders and all actors and potential partners within and outside the health sector should be enlisted to make actions sustainable.

  9. Pursuing horizontal cooperation: identify which countries share problems or borders where the selected diseases occur, to promote joint actions and inter-country plans.

  10. The increased in donor support from global partners in the fight against neglected diseases and other infections related to poverty.

Source: Communicable Diseases (CD), Health Surveillance and Prevention and Control of Diseases (HSD), PAHO/WHO. Taken from the document "Elimination of neglected diseases and other poverty-related infections", (CD49/9 (Eng.) presented during PAHO's 49th Directing Council, July 2009.

 

Notes:

  1. WHO. Global Plan to Combat Neglected Tropical Diseases 2008-2015. (WHO/CDS/NTD/2007.3) Geneva: WHO, 2007.
  2. Hotez Peter. Hookworm and poverty. Annals of the New York Academy of Sciences (1136):38-44, 2008.
  3. Organización Panamericana de la Salud. Plan Estratégico 2008-2012. OPS, Documento Oficial No. 328, Washington DC:PAHO; 2007.
  4. PAHO. Epidemiological Profiles of Neglected Diseases and Other Infections Related to Poverty in Latin America and the Caribbean. Presented at the Consultation on a Latin American and Caribbean Trust Fund for the Prevention, Control and Elimination of Neglected and Other Infectious Diseases. Washington, DC, 15-16 December 2008. Available at: http://new.paho.org/hq/index.php?option=com_joomlabook&Itemid=259&task=display&id=37
  5. PAHO/HSD/CD. Epidemiological Profiles of Neglected Diseases and Other Infections Related to Poverty in Latin America and the Caribbean. Presented at the Consultation on a Latin American and Caribbean Trust Fund for the Prevention, Control and Elimination of Neglected and Other Infectious Diseases. Washington, DC, 15-16 December 2008. Available at: http://new.paho.org/hq/index.php?option=com_joomlabook&Itemid=259&task=display&id=37
  6. Vélez I D, Hendrickx E. Leishmaniosis cutanea en Colombia y género. Cad. Saúde Públic., 2001; 17(1): 171-180, jan-fev, 2001.
  7. Courtright P, West S K. Contribution of sex-linked Biology and Gender Roles to Disparities with Trachoma. Emerging infectious Disease. 2004; 10 (11): 2012-6.
  8. DALYs for a disease or health condition are calculated as the sum of the years of life lost (YLL) owing to premature mortality in the population and the years lost through disability (YLD) for incident cases of the health condition. http://www.who.int/whr/2004/en/report04_en.pdf.
  9. Remme J H F, Feenstra P, Lever PR et al. Tropical diseases targeted for elimination: Chagas disease, Lympahtic filariasis, onchocerciasis, and leprosy. In Jamison D T, Breman Jg, Measham A R et al. Disease Control Priorities in Developing Countries 2ed. Oxford University Press and the World Bank, 2006.
  10. Bitrán, Ricardo. Regional Study to Estimate the Cost of Preventing, Controlling, and Eliminating Selected NTDs in the Americas. Presented at the Consultation on a Latin American and Caribbean Trust Fund for the Prevention, Control and Elimination of Neglected and Other Infectious Diseases. Washington, DC, 15-16 December 2008. Available at: http://new.paho.org/hq/index.php?option=com_content&task=view&id=1231&Itemid=259.
  11. WHO. Global disease elimination and eradication as public health strategies. Proceedings of a conference held in Atlanta, GA, 23-25 February 1998. Bulletin of the World Health Organization, 1998, 76 (2): 22–25.