Regional Program for the Elimination of Rabies Transmitted By Dogs in the Americas
Albino Belotto, DVM, MPH, MSc; Raúl Vargas, DVM, MPVM, MSP; Maria Cristina Schneider, DVM, MSc, ScD; Eduardo Correa, DVM, MSc; Hugo Tamayo, DVM, MSc
The Pan American Health Organization (PAHO) is the regional office of the World Health Organization (WHO) in the Americas. The Veterinary Public Health Unit (VP) of PAHO cooperates with its Member Countries to control rabies in the Region. The Regional Program for the Elimination of Human Rabies Transmitted by Dogs in the Americas is one of the VP Unit's priorities. The goal of the program is to eliminate human rabies transmitted by dogs from the Region by the year 2005.
The information presented below has come from the Regional Information System for Epidemiological Surveillance of Rabies in the Americas (SIRVERA).
The countries' programs started in the 1970s, from then until now human rabies has consistently declined in the Americas. In 1981, a total of 345 human cases were reported, whereas in 2001 there were 60 cases, equivalent to an 83% reduction over the 20-year period. This trend appears to be continuing into 2002.
In the early 1980s, member countries made a commitment to eliminate urban rabies from the principal cities of the Region. This commitment is being met: 19 of Latin America's 21 capital cities have not reported any cases of human rabies transmitted by dogs in recent years.
In 2001, dogs were associated with 42 (70%) of 60 reported human cases where information on the animal transmitter was available. One of these cases was imported into the United States. These autochthon cases occurred in just seven of the 48 countries and territories in the Americas, representing 38% of the Region's population. The countries that reported human rabies transmitted by dogs in the Region in 2001 were: Bolivia (7 cases), Brazil (17 cases), Ecuador (2 cases), El Salvador (3 cases), Guatemala (1 case), Haiti (9 cases) and Mexico (2 cases).
A similar downward trend to human rabies can be seen for canine rabies. Between 1981 and 2001 the number of cases of rabies in dogs fell from 19,654 to 1,652. This significant decrease (92%), was made possible by the enormous effort of the governments of the Region, and with the support of PAHO. Control programs consist mainly of mass vaccination of dogs.
In 2001, 12,486 cases of rabies in animals were reported in the Americas; of these cases 7,800 (62%) were in wildlife. The majority (94%) of all reported cases in wildlife were in North America, which has an extensive epidemiological surveillance system for wildlife. In contrast, the majority (94.2%) of cases in dogs were diagnosed in Latin America.
As rabies transmitted by dogs is being increasingly controlled, human rabies transmitted by wildlife is taking on greater importance. In 2001, almost 15% of all human rabies was transmitted by bats. These cases occur both in Latin America, where the majority of cases are transmitted by vampire bats, and in North America, where the cases are transmitted by other types of bats.
Strategies to combat rabies in the Americas
Efforts have centered on strengthening national programs for the implementation of traditional control measures. Programs include mass vaccination campaigns for dogs, providing human post-exposure prophylaxis via health units, epidemiological surveillance, health education, and control of outbreaks.
Every year, nearly 42 million dogs are vaccinated in Latin America, immunizing approximately 68% of the canine population. The range of vaccination coverage varies 82% to less than 10% to 82%. Low vaccination rates occur in countries that have rabies under control and do not do mass vaccination anymore. During mass vaccination campaign the locations where vaccinations are administered in Latin America typically include places where people gather on a daily basis, such as health units, parks, marketplaces, schoolyards, and even government offices.
Approximately one million people a year seek medical care after potential exposure to rabies. There are nearly 65,000 health units in Latin America where rabies post-exposure prophylaxis is available. This corresponds to a rate of 1.3 health units per 10,000 inhabitants. On average, 35% of people who seek medical care also receive treatment, although the figures vary from country to country. In most of the countries the treatment is free of charge.
In addition, over 100 laboratories are part of the rabies diagnosis network in Latin America. A total of 47,649 tests for rabies were performed in 1998, 7.6% of which were positive. In 1999, 4.5% of 65,049 tests were positive. Of the positive samples, the virus was identified in 185 (5.11%) samples in 1998 and 478 (16.01%) samples in 1999.
PAHO coordinates a regional epidemiological surveillance system for rabies, SIRVERA, which was launched in the 1970s and is essential for analyzing the epidemiology of rabies in the Region and developing control strategies.
Examples of countries that illustrate the effectiveness of rabies control strategies are Mexico and Brazil. In Mexico, the number of vaccinated dogs has systematically risen each year. In 1990, more than 7 million dogs were vaccinated, while in 2000 that figure doubled to 14 million. The number of canine and human rabies cases has declined proportionately to the number of vaccinations administered. In 1990, there were more than 6,000 cases of canine rabies in Mexico, and by 2000 there were 840 cases. Similarly, cases of human rabies fell from 35 in 1990 to 7 in 2001. The situation in Brazil is similar. In 1990, 9.5 million canine rabies vaccinations were administered to dogs, while in 2000 that number was 14 million. There were 13,000 cases of canine rabies in 1990 comparing with 2,700 cases in 2000. The annual number of human rabies cases was 60 in 1992 and fell to 21 by 2001.
Conclusions and Recommendations
Continued success of rabies control programs depends on political and economic consensus to maintain the political and financial commitment to support rabies control programs. For this reason, it is essential for PAHO Member countries to continue to share information in ways that encourages effective support.
Strengthen epidemiological surveillance of rabies in high risk areas and identifying risk factors, especially in undeveloped areas, that are associated with rabies reservoirs.
Because economic resources are limited, it is necessary to establish criteria that emphasize the importance of responding to outbreaks.
Transfer and implement new technologies, such as the use of monoclonal antibodies and polymerase chain reaction diagnostic techniques.
Improve post-exposure prophylaxis by increasing coverage, harmonizing prophylaxis regimens, and the use of Tissue Culture Origin (TCO) vaccines.
Improve inter sectorial coordination on rabies control, particularly between health and agriculture, as well as community level participation.
As the number of canine rabies cases declines, the focus on wild rabies will become more important for achieving sustained rabies control.
Conduct studies on the population dynamic and implementation of rabies control in wildlife.
Focus more attention on surveillance of rabies in wildlife in Latin America.
1. PAHO/WHO. Strategy and plan of action for the elimination of urban rabies in Latin America. Washington DC, 1983 (in Spanish).
2. PAHO/WHO. Bulletin of Epidemiological Surveillance of Rabies in the Americas. Years 1990-1999. Washington DC.
3. PAHO, PANAFTOSA. Bulletin of Epidemiological Surveillance of Rabies in the Americas-2001. Rio de Janeiro, 2002.
4. WHO. Report of WHO Consultation on dog ecology studies related to rabies. WHO/Rab.Res./88.25.Geneva.
5. PAHO/WHO. Guide for organizing, implementing and evaluating mass vaccination campaigns against canine rabies. HPV/R2/124/92. Washington DC.