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SPOTLIGHT Cuba’s Epidemic-Fighting Model INTRODUCTION Designing a model to fight an epidemic involves identifying the basic components of that fight and how to apply them. There are three essential principles: the scientific data that determines how to confront and eliminate epidemics; political (governmental) support, and mass participation in the anti-epidemic program. Additionally, a methodology of working in sequential phases must be added to such an anti-epidemic model. First, a national surveillance system must be established that covers the entire population and provides suitable technical facilities. Second, when the surveillance system identifies the presence of a pathogen, the government, and all levels of the health system, must be alerted. Third, the effort must be directed at the highest levels of government and, without fail, involve all specialties and sectors. Although the public health system must maintaintechnical and logistical support in the event of an epidemic, epidemics are not its exclusive responsibility. Rather, resolute coordination is required across all sectors, coupled with an increase in resources so as to cut short the epidemic and achieve sustainable results. Fourth, the media must be fully involved so it can provide the public with practical instructions. Fifth, the lessons from each epidemic must be folded into the model. Cuba has used these steps to fight the most important epidemics to affect the country in recent years: meningitis, dengue and neuropathy.
Meningitis Until 1975, meningitis B had never been a public health problem in Cuba. The disease appeared with increasing frequency in 1976 with 72 cases, a number never before seen in Cuba, resulting in an incidence of 0.8 per 100,000.[1] The surveillance system identified the problem and the public health system sent out an alert. That was the beginning of the fight against the epidemic that was confirmed over the next two years: in 1978, 175 cases were reported, and another 553 in 1979. The respective incidences were 1.8 and 5.6 per 100,000. In 1981, this situation led to a very important decision: research began on finding an effective vaccine against meningitis B. Cuban scientists were convinced that the only way to contain the epidemic was through mass vaccination against the bacteria. Since no vaccine existed at that time, work to develop one was authorized. Many attempts by highly prestigious institutions outside of Cuba with plentiful resources had all failed. The scientists had complete support from the public health authorities and at the highest levels of government. The vaccine was finally developed following arduous experimental work and field tests. Thus, the first of the three fundamental principles in the model in the struggle against epidemics was applied. Field tests confirmed the vaccine’s effectiveness. Its industrial patent was registered in 19 countries. Trials among boarding school students (52,966 received the vaccine and 53,285 in the control group received a placebo), produced no serious negative reactions. Difference in incidence of meningitis between those receiving the vaccine and those receiving the placebo was statistically significant. Eighty-six percent of those who received the vaccine showed seroconversion, exhibited by only 14% in the control group. Overall efficacy of the vaccine was 69.3%.[2] Based on those results, the pilot plant was replaced with a larger unit that produces 110,000 doses weekly. Later, based on the originality of the product and the practical results achieved, the Cuban Academy of Sciences conferred its Diploma for Best Scientific Work on the group of researchers who developed the vaccine. The World Intellectual Property Organization (WIOP) awarded its Gold Medal to the two principal authors of the patent and a diploma to the other eight authors. Since 1991, the Va-mengoc-bc vaccine has been included in the Ministry of Public Health’s national immunization program, with two doses of the vaccine administered (at three and five months). According to reports from the Pan American Health Organization and the World Health Organization, no other developing or First World country has achieved success similar to Cuba’s amplified immunization program. Following massive application in Cuba, the vaccine has been used in Brazil, Colombia, Argentina, Uruguay, the Dominican Republic, Syria, Guatemala, Chile, Nicaragua, and El Salvador. The vaccine’s subsequent successes include a joint collaboration with the prestigious St. Mary’s Hospital in London, and an agreement with SmithKline Beecham (now Glaxo SmithKline).[3] Since 2000, the incidence of this illness in Cuba has been registered at 0.5 or fewer per 100,000. Hemorrhagic Dengue (HDF), 1981 Martínez’ Dengue y dengue hemorrágico (Dengue and dengue hemorrhagic fever) offers a brief description of the epidemic: In 1981, the hemisphere’s first dengue hemorrhagic fever epidemic appeared in Cuba, caused by the DEN-2 strain. In May of that year, some cases were notified in the Boyeros Municipality of Havana City, involving fever and compatible with a dengue diagnosis. Retrospectively, similar cases were identified in the same place in previous months. The illness was confirmed simultaneously in Havana City, Cienfuegos and Camagüey provinces. Later it spread to the other provinces.
In all, 344,203 cases were diagnosed. The three provinces listed above, plus Holguín, had the highest morbidity. The epidemic peaked in early July, 1981. As a result of the health and hygiene measures, as well intensive vector control, the epidemic subsided, and finally was declared over on October 10 the same year.[4] Of the total of those affected, 116,143 (33.7%) were hospitalized. Of these, 8.8% were considered serious or critical, including both adults and children. This percentage would be much higher if we considered only cases of those under 15. There were 158 deaths. Of these, 99 (60.3%) were under the age of 15, with an average age of 4. The death rate among those hospitalized was 0.13%. In terms of clinical aspects, 24,000 presented with hemorrhage; of which over 10,000 suffered dengue shock syndrome (DSS). In Cuba, the mortality rate caused by HDF/DSS was 0.46 per 1,000 cases. The DEN-2 viral strain isolated in Cuba was genetically related to a Southeast Asian strain that had never before been seen in the region, and that stopped circulating after taking its toll in Cuba, thanks to efficient quarantine measures adopted by the public health authorities for all Cubans traveling to countries in the region. This strain has not been seen again in the Americas (Kourí, G., “La emergencia del dengue en las Américas.” International Dengue Course, Pedro Kourí Institute of Tropical Medicine, Havana, 1997). This account reveals some unusual circumstances. The surveillance system did not discover the first cases as early as in other epidemics; and confirmed cases appeared simultaneously in three areas quite distant from one another. During the second month of the epidemic, morbidity was very high, registering 11,400 cases in a single day. Among the 33.7% hospitalized, the death rate was very low. The low death rate can be attributed to early hospitalization, correct diagnosis and adequate rehydration therapy.[5] Due to the high number of those hospitalized, large schools were converted into hospitals, as the outbreak occurred during school vacation. Medical and auxiliary personnel as well as equipment were dispatched to the schools, and a transportation network set up to take each patient to the most appropriate site, with the most seriously ill taken to facilities with intensive care units. As soon as the epidemic was discovered, an intense campaign against the vector began. Human, material and financial resources were allocated to the campaign. Civil Defense authorities took charge of this aspect of the fight. In the end, the Aedes aegypti mosquito was eradicated in 13 of the nation’s 14 provinces. Approximately 10,000 public health personnel worked full-time in the campaign. An even greater number of volunteers worked in various capacities to eliminate the vector. Public participation was notable.[5] The lessons from this epidemic were substantial and useful applications have emerged. Individual risk factors were identified among the gravely ill and those that died, including:
Furthermore, some important observations have been made by Dr. Kourí and collaborators regarding the illness’s intra-epidemic virulence, seriousness, morbidity and mortality. Among these, it should be noted that more serious and fatal cases appeared as the epidemic advanced.[5]
The short time it took to end the epidemic, combined with the aforementioned low mortality rate and elimination of the vector in nearly the entire country, confirms the model’s capacity to resolve the problem, and the organizational strength offered by a centralized approach. Epidemic Neuropathy
The uniqueness of the neuropathy epidemic presented the national scientific community with its greatest challenge. Its cause, how it was spread, and its treatment were relatively unknown and therefore new to Cubans at the time.[6] In early 1992, ophthalmologists in Pinar del Río Province reported an unusual number of people suffering from a progressive loss of visual acuity, with central or ceco-central scotoma; loss of color perception and scant change in pupil reflexes and ocular fundus. Some cases were accompanied by peripheral neuropathy.[7] At that time there was talk of retrobulbar optic neuritis. In retrospect, the earliest cases appeared toward the end of 1991. The first patients were men from rural areas. Shortly thereafter, a number of cases began appearing of peripheral neuropathy, which includes all non-visual neurological symptoms of the condition, characterized by a feeling of pins and needles, a tickling sensation, numbness, cramping and a burning sensation in the extremities. Less frequently, these symptoms affect other parts of the body. They can be constant or intermittent and tend to increase at night, causing insomnia. Other manifestations may present, thus exhibiting a polymorphic clinical picture.[8] Moreover, cases presenting mixed symptoms appeared with significant frequency. They were patients with the dual symptomatology of optic and peripheral neuropathy. Distribution by gender showed a greater predominance among women (336.8 per 100,000 vs. 287.4 among men). Far fewer cases appeared among those younger than 15 or older than 65. Ramírez et al. offer a synthesis of the epidemic: Analysis of the epidemic identified five distinct phases. The initial phase showed a significant presence in the province of Pinar del Río, unequally distributed among its municipalities. The second phase, occurring between January 1 and March 27, 1993, was characterized by a moderate rise in the optical form in Havana City and Pinar del Río, amounting to 66.1% of the national total. The third phase spanned March 28 through April 10, 1993, with a marked increase in cases and notable incidence of optic neuropathy throughout the other provinces. Of the total number of cases reported, 40.5% were in this two-week period, with an increase in reporting of peripheral neuropathy. Between April 11 and May 28, the fourth phase exhibited an irregular pattern during which the cases of optic neuropathy decreased, while peripheral neuropathy increased, thus reversing the earlier pattern. The fifth phase, from May 29, saw a drop in optic neuropathy and a marked reduction in the peripheral form. By November 1993, the epidemic was virtually halted, with only sporadic cases of both types of clinical presentations.[9] To summarize, the model requires: 1. Political will. Perhaps the best example of this is the personal attention President Fidel Castro gave to all aspects of the epidemic; the intense mobilization of resources, coordinated among sectors by the Civil Defense; government funding of all efforts; and ample participation and cooperation from the international scientific community. 2. Scientific evidence base. The scope of scientific research supporting the struggle against the epidemic was carried out by 57 Cuban institutions and 14 from abroad, which analyzed the causal, physiopathological, diagnostic, epidemiological and therapeutic aspects of the phenomenon. 3. Public participation. Broad dissemination of information and educational material formed the basis for public awareness and cooperation. This provided valuable support for fieldwork carried out be clinicians and epidemiologists, and ensured that preventive orientations were followed, particularly use of multivitamin supplements provided free of charge to the whole population. The absence of public alarm or panic, and people’s confidence in the measures being taken, are results linked to this aspect of the campaign. 4. Epidemiological Surveillance. This first programmatic component - early recognition of an outbreak or epidemic - was fulfilled by ophthalmologists who noted the rise in a very rare or unusual affliction in the area first affected (Pinar del Río). Although there was no orientation to report such cases to the existing data retrieval systems, they did notify the cases to local authorities. Official notification was not put into effect until the 13 th week of 1993—that is, very late. 5. Alerting the public health system and government. The most qualified judgment comes from President Fidel Castro who said: “Unfortunately, at first, when the epidemiology department of the public health system learned of the disease, they worked on their own, didn’t tell anyone, didn’t warn anyone else, until the moment we realized the disease existed. “And some time passed, because nearly all of 1992 went by with isolated cases and there was no official information concerning the problem, not until the first trimester of 1993. Otherwise, we would have done what we did much sooner—coordinating all the research centers and organizing an authoritative group to confront and investigate the problem.”[10] The programmatic element of alerting the health system was fulfilled, but action wasn’t taken in accordance with the magnitude of the phenomenon and the appropriate warning wasn’t given to government—which would have prompted the government to “organize an authoritative group”, as the President said, which was the next step in the program. 6. Unified, high-level management team. Applying this aforementioned measure marked the beginning of controlling the epidemic. 7. Information to the public. As explained in point 3, above. Intensive use of the media was used throughout. CONCLUSIONS These epidemics taught many lessons historically, clinically, and in terms of epidemiology, toxicology, and therapeutics. The meningitis outbreak taught us how to develop a vaccine for our specific problem, while hemorrhagic dengue allowed us to increase and strengthen our intensive care units. The neuropathy epidemic led us to strengthen our epidemiological surveillance system, the driving force behind creation and development of the municipal, provincial and national network called the Health Tendencies Analysis Unit (UATS). REFERENCES
THE AUTHOR
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