Epidemiological Profile of Accidental Tetanus Cases in a Referral Hospital , 2007-2013

Results: there were 126 cases confirmed, mostly male (89%) and from the urban area (77%). The most frequent professions were agricultural workers in general and masons (31.7%), with age group between 35-49 years old (39.7%). The perforation was the most evident injury (48.4%). The lower limbs were the most affected region (65.1%), and the predominant clinical sign was trismus (90.5%). The lethality rate was 19.0%, and the mean length of hospital stay was 49.4 days.


Introduction
Formerly, accidental tetanus was among the most prevalent diseases in Europe and North America.However, it is currently a discrete pathology in these countries due to its social and educational development, mainly due to the immunization carried out correctly in the population.On the other hand, in most developing countries, the disease is not an epidemic in the community, but it is still an important cause of morbidity and mortality [1].
Tetanus remains a public health problem in developing countries, even after more than 80 years of the discovery of the tetanus vaccine.It is estimated that the worldwide incidence of this disease is one million cases per year and occur predominantly in Africa, Asia and Latin America [2].
In Brazil, approximately 1,950 cases of the disease occurred between 2007 and 2013, corresponding to an average of 278 cases per year.The Northeast region has the highest number of cases (36.54%) [3].In 2004, 15% of the cases reported in this region were from the state of Pernambuco, with an average of 40 cases of accidental tetanus annually in the last six years [4].Its tendency is a reduction in the number of cases.However, it still presents with a high rate of lethality [1].
It is observed that although it is an immune-preventable disease and it can be eradicated in Brazil, it is still present and presents a significant mortality rate.According to the Ministry of Health, the continuous lethality is above 30%, being more representative in the elderly.In 2008, this lethality was 34% and considered high when compared to the developed countries, where the lethality is 10 to 17% [5].
Besides presenting lethality, treatment of tetanus is expensive because it requires intensive care in severe cases.Thus, this situation requires actions ensuring the wide protection of the population, through vaccination and improvements in medical-hospital care [1].
The fact that the incidence and lethality of tetanus are much higher in Brazil than in developed countries, and the disease is related to environmental and behavioral risks; it is essential to characterize the disease in hospitalized patients in the country.
This study aimed to describe the epidemiological and clinical profiles of cases of accidental tetanus in hospitalized patients in a referral hospital in the state of Pernambuco, PE, as well as to present the lethality rate and to know the average length of hospital stay.

Methods
This is a descriptive, retrospective study, with quantitative analysis, based on secondary data.The study was developed in a University Hospital of reference for the Northeastern region in infectious and parasitic diseases, located in the city Recife, PE.
The sample consisted of the total of patients diagnosed with accidental tetanus (ICD-A35) hospitalized in the referred service and notified through the SINAN (Information System for Notifiable Diseases) from 2007 to 2013.Patients were included in the sample with age greater than 28 days.The cases that had the final classification as the discarded diagnosis were excluded.
For the collection, the data of the epidemiological investigation charts of Sinan were used.Their compilation was done through the software Tabwin®, generated from Sinan.The MV 2000i management system was used to calculate the mean length of hospital stay, possible to observe the period between hospital admission and hospital discharge.
The descriptive analysis for the categorical variables was analyzed by simple frequencies, while the numerical variables were analyzed according to a central tendency (mean and median) and dispersion (standard deviation).The research project was approved by the Research Ethics Committee of the Oswaldo Cruz University Hospital, under CAAE 36259514.3.0000.5192.

Results
During the study period (2007-2013), there were 126 cases of accidental tetanus reported in the service.An average of 18 cases per year was observed in this period and a reduction of more than 50.0% of the cases in the last two years.About the age, most of those affected by the complaint are in the age group of 35-49 years old (39.7%), followed by 50-64 years old (25.4%).There was a predominance of males, with 89%.Most cases were coming from the urban area (77.0%).Regarding the occupation, most of the cases were concentrated among the agricultural workers in general and the masons.However, in 12.7% of the cases analyzed, this variable was ignored, according to data from Table 1.
Regarding the vaccine history, only 2.4% of the patients presented complete vaccination scheme, while most of them, 46.8%, did not present prior vaccination records in previous periods.Also, 41.3% had this information ignored in the Sinan research chart, according to the data in Table 2.
Regarding the type of wound, perforation was the most frequent with 48.4% of the cases; the lower limbs was the most affected region, corresponding to 65.1%.Among the characteristic signs of the disease, there was trismus (90.5%), contracture crises (68.2%) and neck stiffness (48.4%), being the main signs, associated or not with each other (Table 3).
Regarding the final classification, 74.6% of the 126 reported cases of accidental tetanus evolved   4).

Discussion
This study describes the epidemiological behavior of accidental tetanus of hospitalized patients in a referral hospital in the state of Pernambuco during 7 years.Over the years, there has been a significant reduction in the cases, especially during the last two years.The decline of the disease is a trend in several developing countries, as well as in other regions of Brazil.It is possible that this fact is the result of the better social, economic and educational development in Brazil, the increase in the population´s vaccination coverage, and the better care given to trauma patients [3,6].The results of this research point to a predominance of cases in males.Other similar Brazilian studies have shown that this part of the population is the most affected by the disease [1,2,4,7].This situation has been explained by the fact that men are more numerous in the labor market and, consequently, more exposed to occupational accidents risks, as well as the health strategies directed to this public are still incipient in the country [8].
Regarding the origin of accidental tetanus cases, the predominance usually occurs in the rural area.However, the results of this research reveal that most of the cases occurred in the urban zone, corroborating with epidemiological studies developed in the states of Ceará and Santa Catarina [1,9].From the 1990s, Brazil presents an increase in the number of cases of accidental tetanus occurring in the urban zone, which can be attributed to rural exodus [10].
Regarding patient occupation, the most frequent professions among the cases studied were agricultural workers in general and masons (civil construction), accounting for 31.7% of the total number of patients affected by tetanus.Repeating the results found in a study carried out with 131 patients in the State of Ceará, in 2007, with professions totaled 32.0% of the cases.These results reveal the direct relationship between illness and occupational risk individuals are exposed [11].For that reason, they are groups with essential rethinking the strategies of expansion of vaccination coverage and actions of health education with an emphasis in this population.
The most affected population by the disease was in the age group of 35-49 years old, followed by 50-64 years old, reinforcing the results found in an epidemiological study of accidental tetanus developed in Brazil [10].There is evidence that tetanus reaches a higher proportion of the most productive age group, and can be justified by the greater exposure of this group to traumatic injury, and there is a greater easiness of infection in the work exercise [7].Also, the elderly population was affected by the disease significantly, reiterating the results found in other studies [2,4,9].The risk of major involvement in this group is justified by the decrease in immunity, as levels of tetanus protective antibodies decrease with advancing age [12].Moreover, over the years, the human being loses psychomotor capacity and perceptions of space, being more prone to accidents [13].
For adequate control of tetanus, the complete vaccination schedule with three doses of tetanus toxoid and one booster dose every 10 years from the last dose [5] is required.Some immunological studies indicate that only two doses of the tetanus vaccine provide 90% protection against the immunological protection, and with the three doses of the vaccination schedule, this protection reaches close to 100.0%, evidencing its high immunological efficacy [14].
Of the most affected age group by the disease, none of the patients had a complete tetanus vaccination schedule, and the vast majority reported never having been vaccinated, demonstrating a gap in preventive measures against the disease, since these patients were not included in the programs of immunization programs, even with the expansion of the Family Health Strategy program.
Another important aspect to vaccination was the high percentage of cases with the filling of the vaccine variable ignored.Therefore, it is inferred that such information may be the result of a lack of knowledge of the vaccination situation, which is one of the major problems faced in vaccination in adults, who do not preserve their vaccination record [1].
By associating the occupation with the previous vaccination history, most agricultural workers in general and the masons (civil construction) were never vaccinated or had the dose ignored or had incomplete vaccination schedules, which justifies the failure of vaccination and consequently the high frequency of the disease in these groups.
As the most common type of injury, perforation has been described in most of the cases studied, similar to other national studies [1,2].It was also observed that the bruises and lacerations were gateways to the disease, corroborating data found in the southern region of the country [9].Any solution of continuity with the presence of necrotic tissue, contaminated with soil, dust, and feces, favors the colonization of the bacterium after spore deposition, justifying the occurrence of cases resulting from burns, surgical wounds, infected abortion, dental caries and leg ulcers.The lower limbs were also the topography of the most affected wound, corroborating with other casuistics [1,2,7,9].
Regarding the clinical picture, trismus was the most evident characteristic sign in the analyzed cases.Similar data were confirmed in studies conducted in Ceará and in the interior of São Paulo, where they found this finding in 50-75% and 72.7% of cases, respectively [1,2].
The research reveals that tetanus lethality was considered high (19.0%)when compared to a study carried out in the interior of São Paulo, where there was no tetanus mortality in 20 years (1990-2009) [2], and another study in the same State in 2011 showed a lethality of 9.1%, a rate comparable to high-quality services in developed countries [15].
In 2009, a study was carried out in the state of Pernambuco, in the same reference center of this study and the impact of intensive care unit assistance on tetanus lethality was evaluated, where a lethality rate of 12.6% after the introduction of intensive care was found [4].Such evidence confronts the results found in this study, demonstrating a need to improve the health care quality of the health network in this State.
When associating death with the age group, it was observed that the lethality predominates in the individuals between 35-49 years old, an age group that presented the highest frequency in this study.Also, those aged 65-79 years old were the second age group most affected by death.It can be concluded that besides the disease that affects individuals with missing, incomplete or inadequate immunization, age above 51 years old is also a risk factor for this condition [7].
The mean length of stay in the studied cases was higher when compared to other cases.In the State of Ceará, the researchers observed an average of 22 days of hospitalization, from hospital arrival to hospital discharge.In the State of Bahia, in a study with 119 cases of accidental tetanus analyzed between 2004 and 2010, this average was 20 days [7].
Considering tetanus treatment most often requires intensive care unit due to its complications, and the cost of this care becomes very costly for the State due to the increase in Hospital admission, it is concluded that effective vaccination of the population is the best strategy to reduce the frequency of the disease.

Conclusions
Despite the limitations found in the data of the notification form and epidemiological investigation, preventing the analysis of important information to reach the proposed objectives, it is concluded that this study contributes to the description of the epidemiological situation of accidental tetanus in the State of Pernambuco, evidencing this pathology is a major public health problem, mainly because it is an immune-preventable disease.Therefore, it is expected that it will be a basis and aids in formulating and evaluating care measures (preventive and curative), especially in strategies that increase vaccination coverage in the most affected groups and control the disease, with appropriate treatment of wound and encourage further studies.

Table 4 .
Final classification of reported cases of accidental tetanus in a University Hospital of Pernambuco, 2007-2013.Recife, PE, Brazil, 2015.