Introduction
Despite impressive progress in medicine made in recent decades, studying the world’s most dangerous diseases is still a crucial objective and requires a large amount of work to be done. That is why sciences as epidemiology become more and more important for humanity. According to its definition, epidemiology is a field of study which determines the causes of various diseases and particular health outcomes. This science deals with issues of distribution, determinants, and events in definite groups of people.
Approaches
As a science, epidemiology uses several different approaches. The ones most frequently applied are analytical and descriptive methods which are interdependent and highly important for the study. On the one hand, descriptive epidemiology provides a basis for further research either practical or theoretical. Epidemiology deals with numerous aspects of research, its key issues are represented by the so-called 5W’s of epidemiology. Those include:
- What (the main concern of a patient);
- Who (patient himself);
- Where (location);
- When (period);
- Why/how (reasons).
The purpose of the descriptive approach is to provide a comprehensive overview of the situation which implies answering the three questions out of five mentioned, namely Who, Where, and When. Those are usually interpreted as a description of a person, place, and time. Determination of a period when a disease occurred is a crucial objective of the research, as it helps scientists to predict its appearance and, accordingly, to prevent it. A detailed description of a place where the disease is located allows one to understand its geography and focus on a particular area for the study to estimate the probability of contamination of different communities. Finally, specification of a patient’s profile is a way to discover if personal characteristics influence the risk of contamination or it is inherent to anyone, despite his or her age, race, sex, etc. Consequently, the descriptive method is only used for the detailed representation of the main patterns and features of the disease and provides its full profile for future analysis.
Differences Between the Descriptive and Analytical Epidemiology
While descriptive epidemiology deals with a representation of facts only, the analytical approach is applied for the examination of possible causes and effects of the disease, or in terms of issues, it’s the why and the how. In other words, it analyzes the data about the illness collected using a descriptive approach. Its main feature is a comparison group which simply implies the study of people with common symptoms, reactions, and definite features. Such research aims to reveal causes, risk factors, and patterns inherent to an illness.
Taking everything into account, the following differences between the descriptive and analytical epidemiology might be found:
- Descriptive epidemiology provides the data which is examined under analytical approach;
- Descriptive epidemiology might generate a hypothesis, while analytical epidemiology tests one;
- The key issues the descriptive approach deals with are characteristics of a person, time, and place; analytical epidemiology studies causes and risk factors.
Typhoid Fever Epidemiology
History
Some researchers are convinced that typhoid fever was the reason of a plague in Athens, dating back to 430BC. It is thought to be responsible for infection of some famous leaders of that time, such as Pericles and Thucydides. Another case which is assumed to be connected with the typhoid fever is elimination of Jamestown colony in Virginia. There have been a large number of similar cases, though due to some issues related to verification of historical facts the precise origin of the disease remains unknown.
Being originated from the Antient times, typhoid fever still threatens lives of thousands of people globally. Yet, considerable progress has been made in this field, and many counties have already experienced a decline in the number of cases of infection. For instance, the overall number of people contacted with the disease during 2015 constituted 17 million in absolute terms (Als et al., 2018). As for the US statistics, the level of indicator there is much lower. It accounted for 3373 cases only in absolute terms during the period from 1999 to 2010 (Ayers et al., 2015). At the same time, the amount of deaths worldwide reached 178,000 (Als et al., 2018). The discrepancy is quite reasonable, as the expansion of the typhoid fever is not completely random, considering its dependence on many different factors. Usually such patterns are based on a concept introduced by a so-called epidemiological triangle.
Causes
In its core the concept of epidemiological triangle implies three basic causes of the disease. Those causes are represented by components defining the progress of the disease which are agent, host and environment. The first one is simply a carrier of an illness and might be presented by bacteria, virus, poison, trauma, radiation etc. In case of the typhoid fever the disease is caused by Salmonella enterica serotype Typhi (Ayers et al., 2015). A further expansion is usually due to contaminated water and food (Crump, 2019). As the bacteria spreads inside the body, a host, or a person, plays a key role in its survival. Salmonella Typhi is almost unable to multiply outside of a reservoir (a human), yet, it is capable of surviving a long period in the outer environment.
Spread
Considering the dependence of disease spread on quality of food and water, as well as general sanitary conditions, it becomes clear that people from low-income dysfunctional families are more likely to be infected. What is more, communities living in regions where clean water is a scarce resource have an increased probability of infection via nutrition. Consequently, the last risk factor is an unsafe environment, which implies the absence of clean water and adverse sanitary conditions.
Antidote
The key purpose of examination of the typhoid fever, as well as other similar diseases, is to reveal an ultimate antidote or a way to prevent its spread. The most effective approach is probably a comprehensive one which consists of several steps. Firstly, it requires an overall improvement of sanitary conditions, such as water and food quality. Secondly, this method implies a compulsory regular vaccination, which proved its effectiveness multiple times. Researchers note that “The use of vaccines in the control of typhoid fever has been successful as a preventative measure and during outbreak situations in … China, during the 1999 typhoid outbreak, … vaccine showed a protective efficacy of 73% in children previously vaccinated and 71% in children who received the vaccine during the outbreak” (Als et al., 2018, p. 6). Accordingly, the mentioned steps are the most efficient way to avoid the disease discovered so far and should to be implemented in regions with a highest rate of infection.
As it has already been mentioned, a lot of effective measures have been taken in recent years. However, plenty of work in this field is yet to be done. For instance, according to Bhutta et al. (2018), “Our findings revealed … that outside of high-income countries, there were very few reliable population-based estimates of typhoid fever derived from robust surveillance systems. Hence, regional estimates of typhoid fever burden and trends from many large geographic regions representing LMICs were not available.” (p. 90). Consequently, the data about a number of cases and deaths is still unavailable, thus, the overall rate of population informed about preventative measures is rather low.
Conclusion
What is more, such imprudence assumes a low percentage of vaccinated people, as a result of the government’s ignorance of the situation. Therefore, some actions towards the improvement of informational and prophylactic policies would make a great difference. In this way, one also might consider ecological measures to be a huge step in resolving the problem because a considerable amount of cases is due to contaminated food or water. Taking such small steps, humanity can solve this issue once and for all.
References
Als, D., Bhutta, Z., Breiman, R., Crump, J., Mintz, E., Radhakrishnan, A., Stanaway, J. (2018). Introductory article on global burden and epidemiology of typhoid fever. American Journal of Tropical Medicine and Hygiene, 99(3), 4-9.
Ayers, T. L., Derado, G., Freeman, M., Gonzalez-Aviles, G., Halpin, J., Kendall Scott, M., Vieira, A. (2015). Typhoid fever acquired in the United States, 1999–2010: epidemiology, microbiology, and use of a space-time scan statistic for outbreak detection. Epidemiological Infection Journal, 143, 2343–2354.
Bhutta, Z., Black, R., Breiman, R., Crump, J., Gaffey, M., Levine, M., Luby, S., Steele, D. (2018). Typhoid fever: way forward. American Journal of Tropical Medicine and Hygiene, 99(3), 89-96.
Crump, J. (2019). Progress in typhoid fever epidemiology. Clinical Infectious Diseases, 68(1), S4-9.