'ItNDEXED & 4. Pan American Health Organization. PAHO/ACHR/23/3.7 Original: Spanish

Transcription

1 'ItNDEXED Pan American Health Organization TWENTY THIRD MEETING OF THE ADVISORY COMMITTEE ON HEALTH RESEARCH & 4 PAHO/ACHR/23/3.7 Original: Spanish Washington, D.C. 4-7 September 1984 RESEARCH PRIORITIES VETERINARY PUBLIC HEALTH PROGRAM : h The issue of this document does not constitute formal publication. It should not be reviewed, abstracted or quoted without the agreement of the Pan American Health Organization. Authors alone are responsible for views expressed in signed papers.

2 PAHO/ACHR/23/3.7 OBJECTIVES OF THE PROGRAM The overall objectives of the program are the following: - To reduce human morbidity and mortality due to zoonoses. - To fight human malnutrition by increasing the supply of animal proteins. - To prevent infection and poisoning caused by food and reduce economic losses, by protecting and guaranteeing the quality of the food supply. - To promote human welfare and health in general by applying the appropriate technology and knowledge to veterinary public health. REVIEW OF PAST RESEARCH IN THE PROGRAM OF VETERINARY PUBLIC HEALTH Zoonoses are diseases transmitted by animals to humans and represent a great health problem in the Americas. They are of great medical significance, causing considerable morbidity and mortality among human groups that have been identified as having special needs under the Plan of Action for Health for All by the Year The populations vulnerable to zoonoses include children, teenagers, mothers, workers, adults and the disabled, all of whom have proved in one way or another to be highly sensitive to a number of influencing factors that can jeopardize their health and welfare in rural and urban areas throughout the world. Zoonoses cause occupational diseases among workers and their families. In Latin America and the Caribbean approximately 273 million people are exposed to over 150 known zoonoses. At least 50% of these people (some 186 million) will contract one or more zoonotic infections in the course of their lives. Zoonoses, including foot-and-mouth disease, undermine the health of animals and reduce their productivity, which results in a decline in Llie production of meat, milk, eggs and wool, as well as in the working capacity of draft

3 -2- animals. In this way, those diseases aggravate the shortage of animal proteins O for human consumption. Scientific evidence has proved beyond doubt that the health of peopleis greatly affected for good or ill by the food they eat. In addition to providing nutrients, foods are also a medium through which humans are exposed to toxic agents and infections. Food interacts with the three basic components of the environment (air, water and soil), which may be polluted by any chemical or biological substance. In most countries in the Americas, many foods reach the consumer at the end of a long chain involving production, processing, distribution and sale. Toxic and infectious agents may enter the chain at any critical phase. Furthermore, many foods provide an excellent medium for the development and multiplication of dangerous microorganisms, which, once ingested, reproduce rapidly. Humans, as consumers, are situated at the end of the chain and are thus exposed to large quantities of toxic agents that can be much more concentrated in foods than in other products. The purpose of the research done under the Program of Veterinary Public Health is to obtain enough data to solve specific problems that arise in national programs for the control of zoonoses, including foot-and-mouth disease, food protection, comparative medicine and public health. Following are some of the contributions of the Program of Veterinary l>ub.lic 1lc IL Lii Ltal: lí ad tvc te greale st iulpact on huiíin huaic lt and sucio-ccoisomic development in Latin America and the Caribbean: 1. The development and transfer of technology for the production of suckling mouse brain (SMB) vaccine against rabies based in the research of Fuenzalida and Palacios'at the Instituto Bacteriológico in Chile. This vaccine has re- 0

4 -3- placed the conventional vaccine made from the nervous tissue of domestic animals, which caused nerve paralysis in humans. SMB vaccine is now used throughout the region for the prevention of rabies in humans and animals. 2. Tile developmncnt and transfer of teclhnology for tlhe production of oil-adjuvanted foot-and-mouth disease vaccine, through the initial collaboration of PANAFTOSA with the Plum Island Animal Disease Center in Lhe United States. This vaccine confers long-term immunity to foot-and-mouth disease which has reduced the number of shots of vaccine administered and therewitlh Jowercel tle cost of vaccination programs. 3. Several studies have been done at PANAFTOSA which have helped develop or refine and transfer methods for the diagnosis of vesicular diseases in animals, in the selection of strains for the preparation of foot-and-mouth vaccine, in the production of antigens for foot-and-mouth disease vaccines in designing methods of vaccine control, in the study of the pathogenesis, transmission and reservoirs of the foot-and-mouth disease virus, improvement of laboratory techniques for research on foot-and-mouth disease, the study of factors influencing the epidemiology of foot-and-mouth disease, analysis of the means of controlling foot-andmouth disease, epidemiological models for foot-and-mouth disease, and the study of production losses and reduced productivity among cattle due to foot-and-mouth disease. 4. The research carried out by CEPANZO has yielded a simple, innovative test for tlhe detection of Echinococcus granulosa (hydatidosis) cysts in!huimans. The test is quite reliable and highly specific for the immunodiagnosis of hydatidosis (arc 5 double diffusion). It is currently used in various hospitals in rural areas, in where the incidence of the disease is traditionally higli. Cases can be detected promptly by this method, so that medical care can be given ear- IP!

5 lier and hospitalization is shorter. In addition, use of the test as an epidemiological method opens up the possibility of developing guided control programs. This, together with the innovative techniques established by CEPANZO for the control of the parasite in dogs (final host), has helped strengthen control programs. 5. The research carried out by CEPANZO and the data from studies conducted in other countries have deterimined the spread and impact of the zoonoses in thle Amiericas, with respect not only to their inroads on public hlea] til bul also to the economic losses they inflict. 6. The establishment of a Center for Non-human Primate Reproduction and Conservation in Peru, in association with the National Institutes of Health of the United States, to protect endangered species of non-human primates in the Western Hemisphere, to promote their breeding in captivity and in their natural habitat. Non-human primates are models for the study of various human diseases 4 such as malaria, hepatitis, herpes and others. In the Center for Non-human Primate Reproduction and Conservation at Iquitos, Peru, several studies are being done on behavior, reproduction, nutrition, etc. Similar centers are being founded in other countries. 7. The design and implementation of a continental surveillance system for foot-and-mouth disease and other vesicular diseases in animals in the region, using map quadrants. This system, considered very effective, provides inforniation for prompt detection of diseases, identification of the areas involved and control of outbreaks. 8. Establishment of a network of laboratories for the rapid diagnosis, typing and subtyping of the foot-and-mouth disease virus and other vesicular diseases in every South American country. Standard techniques are used and re- O

6 -5 - sults interpreted on the basis of standard criteria. This laboratory network has helped the countries obtain precise diagnoses of the disease, monitor changes in the virus, and develop vaccines of the exact type and subtype for the control of outbreaks. * >CRITERIA USED FOR THE ESTABLISHMENT OF PRIORITIES IN THE PROGRAM OF VETERINARY PUBLIC HIEALTII The most important criteria used for the establishment of priorities in the Program of Veterinary Public Health are the following: 1. Research for the solution of current problems in national programs for the control of zoonoses, including foot-and-mouth disease, the protection of foods and laboratory animals, using appropriate technologies. Some of the most significant examples are as follows: In rabies, the shortage of vaccine is one of the most important problems in controlling the disease in domestic animals. Although the SMB vaccine is efficient, the countries in the region cannot produce as much of it as they need. Large-scale production of tissue-culture rabies vaccine could help meet the needs for vaccine in the Hemisphere. Another important aspect is improvement of the quality of SMB vaccine, widely used in both humans and animals. Antigenic differences between strains of rabies virus have been detected using monoclonal antibodies (MCA) prepared at the Wistar Institute. Analysis of ccrtain strains, isolated from humtiian cases that were falal despite adininistraltion of the vaccine, showed that treatment failure was sometimes related to differences between the strain used to prepare the vaccine and the strain at large in the animal popul]ation. Concerning hydatidosis, there are no drugs that can be easily administered to dogs infected with the adult forms of E. granulosa. Neither have any

7 -k -6- drugs been proved effective in the treatment of the larval form of human hydatid. Recent studies on mice have shown that certain drugs are efficient in the treatment of cysts. In prograíms for thlc figlit against tuberculosis, straiin identification and prevalence studies are especially important. Anotlier ficl.d of action is study of the resistencc of thl-e bacilli toantituberculosis drugs. Ceniieraizeud use of certain drugs may give rise to a rapid increase in bacillary resistence to thlem. In the diagnosis of leptospirosis, microscopic agglutination is the reference test for the presence of specific leptospiral antibodies. This is a specialized technique, however, requiring maintenance of many cultures for use as antigens, and is not performed routinely in most diagnostic laboratories. To solve this problem, numerous blood tests, including complement fixation and passive hemagglutination, have been adapted for diagnosis of leptospirosis. Although these are also rather arduous procedures, they take only one specific antigen of the genus to detect antibodies in a blood sample. However, a simple, reliable, rapid and preferably genus-specific test that can be used to test a large number of blood samples is undeniably needed. In addition to hydatidosis, there are other parasitic zoonoses of importance in public health. Cysticercosis is common in cattle and swine in Central America and Andean countries, and humans are infected by eating infected meat. Trichinosis, mainly seen in countries of the Southern Cone, can cause high morbidity and mortality in eaters of infected pork. Fascioliasis, widespread in the Andean area, not only causes losses in meat, milk and wool production, but can also infect humans and lead to serious disorders. Toxomplasmosis is widely dis- - seminated in the region and creates severe problems in animals and humans, especially children. Leishmaniasis, usually sylvatic in prevalence, has become

8 -7 - urbanized with dogs as hosts, and is causing serious public health problems in various South American countries. Contamination of meat, milk, fish and eggs by Salmonella and other bacteria leads to diarrlhea in huimans, especially childrcn, und the morbidity and mor- X tality are higli. Studies on contamination by Campylobacter, Yersinial, E. coli and other bacteria that cause diarrhea in humans are particularl.y imiporlant because they yield useful data on the role of food in the transmission of such diseases. Other food studies are concerned with the control of residual hormones, pesticides, antibiotics and heavy metals, and are of fundamental importance because the presence of these substances in food is injurious to public health, and the merit high priority as requirements for international trade. 2. Mandates of the Governing Bodies of the Organization: in most cases the criteria are based on the mortality and morbidity of the disease and on the risk of contracting it. 3. Studies of research coordinated with research institutes in the countries on problems of mutual interest to the institute and PAHO. 4. Recommendations from the Scientific Advisory Committees (SAC) of CEPANZO and PANAFTOSA, which meet every other year. RESEARCH PRIORITES AND GOALS PRIORITIES 1. Zoonoses 1.1 Rabies a) Development of vaccines, b) development of simple, rapid and reproducible methods of diagnosis, c) study of the ecology and dynamics of the canine population, and d) immunological studies of rabies virus strains using monoclonal antibodies.

9 Hydatidosis a) Evaluation of the efficiency of drugs in the treatment of the larval and adult forms of E. granulosa and b) epidemiological studies. 1.3 Brucellosis a) Evaluation and development of diagnostic tests for humans and animals; b) possible interference of foot-and-mouth disease vaccine and iiiiiiunity conferred by the B. abortus strain 19 vaccine when administered simultaneously; c) epidemiological studies. 1.4 Tuberculosis a) Study of the prevalence and identification of the strains; b) study of drug-resistance; and c) evaluation of sensitivity tests. 1.5 Leptospirosis a) Adaptation of methods of diagnosis and b) epidemiological studies on disease prevention. 1.6 Other Zoonoses Cysticercosis, toxoplasmosis, leishmaniasis, trichinosis, fasciolasis, etc.: a) Studies of prevalence and epidemiology; b) socio-cultural implications; and c) economic losses. 2. Foot-and-Mouth Disease a) Studies of strain differentiation and antigen structure (immunochemistry and monocolonal antibodies); b) development of better methods of vaccine production and disease control; c) adaptation of diagnostic methods (tle ELISA test, etc.); d) studies in genetic engineering; e) epidemiological characterization and evaluation; and f) social and economic consequences of the disease. 3. Food Protection a) Food microbiology, b) aspects of contamination of food by diarrheaproducing zoonotic agents such as Campylobacter, Yersinia, Vibrio and E. coli;

10 -9- and c) epidemiology of food-borne diseases. 4. Comparative Medicine and Public Health a) Conservation and breeding in captivity of non-human primates; b) behavioral studies; and c) animal models for malaria, hepatitis, Chagas' disease. GOALS The Program of Veterinary Public Health, especially through CEPANZO and PANAFTOSA, will collaborate closely with Member Governments in the research programs necessary to achieve the following goals by the end of the decade. - Elimination of urban rabies from major Latin American cities; - Eradication of brucellosis and tuberculosis, in at least 8)% of Latin America and the Caribbean; areas; products; - Reduction of the incidence of hydatidosis to less than 1% in endemic - A significant reduction of outbreaks of food poisoning from animal - A significant increase in the per capita supply of animal proteins (meat, milk and eggs), especially in vulnerable population groups; - A significant decrease, in at least twenty countries in the Region, of morbidity and mortality from food-borne diseases and of losses incurred due to contamination and improper handling of foods; - I>rocu's-illg olf at.i.c IsL 80% ol Llhe fuod in Lhe iueil.,1on in adlcqualt Sanitary conditions; - Implementation of national animal quarters for breeding lines of labo- *7 ratory animals with clear cut characteristics and proper feeding and handling system; and.

11 Establishment of programs for the conservation in their natural habitat and breeding in captivity of non-human primates used for biomedical research in countries. r, 1 A\