Description of Epidemiology, Epidemic, and Pandemic
Epidemiology refers to the study of the spreading and causes of events or cases associated with health and the use of the same study to regulate the infection and other challenges of health. Epidemiological investigations use methods such as descriptive studies and surveillance to study the spread of diseases. Also, it uses analytical studies to study the causes. The epidemic is the sudden increase of disease cases above the normal expectations in a particular population of a specific area. On the other hand, a pandemic is an epidemic that has propagated over various continents or countries, normally affecting a lot of people.
SARS refers to a viral respiratory disease. The illness is triggered by a coronavirus known as a severe acute respiratory syndrome-related coronavirus (SARS-CoV) (“SARS | Basics Factsheet | CDC”, 2018). SARS was first recognised in Asia in the second month of the year 2003. Basing on the Centre of Disease Control and Prevention (CDC) and the World Health Organization (WHO), the incubation period of SARS is two to seven days but may extend to ten days. Usually, coughing, difficulties in breathing, high fever and X-ray changes similar to those of pneumonia are the early symptoms of SARS. Rigorous watery diarrhoea is also a symptom of SARS (“SARS | Basics Factsheet | CDC”, 2018). The World Health Organization (WHO) indicates that SARS affected 26 countries in continents such as Asia, North, and South America and Europe resulting in about 8000 cases of the disease and 774 deaths globally (“WHO | SARS epidemiology to date”, 2018). About 21% of the cases occurred in healthcare workers while the general disease fatality rate was 9.6%.
In 2003, various scientists focussed their attention on civets (cat-like mammals). Their scientists identified SARS infected civets at a general market in the Guangdong province of South China. However, since further studies failed to reveal more infected civets, the scientists suggested that civets were not the original source of SARS (Smith, Montgomery, Kilroy, Tang and Müller, 2015). Thus, the scientist continued their work. Then, in 2005, several teams of scientists independently identified large reservoirs of the SARS virus in the horseshoe bats of China. Consequently, the bats are now both the victims and culprits of the then mysterious epidemic. Therefore, the bats are the source and carriers of the SARS-CoV virus. The scientists suggested that the virus was passed to human beings through direct contact with the bats as they were captured and taken to the Chinese market where people used to eat them (Smith, Montgomery, Kilroy, Tang and Müller, 2015).
What is SARS?
Scientists identified fruit bats or Flying foxes to be the natural reservoir of the SARS-CoV virus. The virus was then transmitted to human beings by close contact with the infested civet cats. Normally, direct and indirect contact of the mouth, nose or eye mucous membrane with the infected fomites or respiratory droplets leads to the higher spread of the disease. The coughs or sneezes of the infected people always generate the respiratory droplets that enhance transmission through direct or indirect contact. Thus, close contact and respiratory droplets are the main transmission means of the virus with the maximum shedding of the virus occurring during the tenth day of the disease. Rigorous diarrhoea (which is an early symptom of the disease) produces faeces infested with the virus. Shedding of the virus occurs in faeces with surface-dried faeces enhancing the survival of the virus for days.
By March 2003, it was clear that medical experts were addressing a severe new disease. Consequently, organizations such as the World Health Organization (WHO) named the infection Severe Acute Respiratory Syndrome (SARS) and declared it a world-wide emergency (“WHO | SARS epidemiology to date”, 2018). A team of microbiologists, public health experts, disease specialists, and epidemiologists was gathered to explore and contain the illness. Special attention was centred on the province of Guangdong in South China where it was indicated that cases of the serious respiratory disease symptoms similar to those of pneumonia had occurred since the year 2002. By mid-April 2003, the assembled team of scientists had identified the determinant organism as a novel coronavirus and managed to isolate it. The team named the causative organism as SARS-CoV. The team used molecular methods to identify various viral strains and track the spread of the sequenced viral genome. The speed at which the global community responded to SARS cases stopped the incidence of a more severe pandemic.
After the control of SARS in 2003, WHO indicates that preparations for a possible future outbreak involve the strengthening and restoration of the public health setup. For instance, more public health experts and epidemiologists are required (“WHO | SARS epidemiology to date”, 2018). Also, response and surveillance systems should be implemented for the strong regional, national and worldwide reporting linkages. The governments should also invest heavily in healthcare infection control and initiate systems for disseminating health emergency notices to tourists and travellers who may have been in contact with severe respiratory syndrome cases.
Source of the Infection
Results from the blood examination provide a proper picture for the pathophysiological analysis. First off, the hemoglobin levels are lower than normal indicating an anemic state. The abnormality in hemoglobin levels is coupled with low ferritin levels and low transferrin saturation. Reduced ferritin levels and transferrin saturation also signify an anemic condition (Medlineplus.gov., 2018). Low ferritin levels often result from a heavy blood loss due to injury, bleeding in the gastrointestinal tract, poor absorption of iron in the GIT, or chronic intake of food with poor iron concentrations (Medlineplus.gov., 2018). The low transferrin saturation indicates a prolonged bleeding condition in the digestive tract, poor iron absorption because of some underlying conditions in the gastrointestinal tract, or a poor supply of dietary iron.
The blood test also reveals that the patient presents with a corpuscular volume of low mean. The low mean corpuscular volume indicates microcytic anemia, which is confirmed by the blood slide examination. The blood slide exam also shows that the red blood cells are hypochromic hence microcytic hypochromic anemia. Microcytic hypochromic anemia is highly associated with iron deficiency anemia but in this case, the iron levels in the blood and the total iron binding capacity are normal (Chaudhry and Kasarla, 2017). Other than iron deficiency anemia, the microcytic hypochromic state of the red blood cells can be attributed to lead poisoning, chronic disease, and acute or chronic loss of blood due to various conditions (Chaudhry and Kasarla, 2017). The white blood cell count exists within the normal range hence showing that the patient is not suffering from acute bacterial or parasitic infection. With conditions such as ancylostomiasis, the blood cell investigation would include a measure of the eosinophils, which in a positive case would present with eosinophilia. The platelet count is also normal thus signifying a normal clotting process unless in conditions where an ulcerated surface encounters persistent irritation.
The mid-central pain that occurs in the abdomen is an important diagnostic factor as it raises suspicion over anomalies in the gastrointestinal tract and other organs in the region such as the liver and spleen. The etiology of the pain is however gastrointestinal due to the nature of its presentation. The pains occur mostly and intensely during the night which gives a clue of a possible ulceration of the GIT mucosa. The soothing character of the antacids confirms the presence of ulcers in a region of the gastrointestinal tract where acidic substances are the main secretion. Acids are known to irritate the lining of the gastrointestinal tract especially in situations where the mucosal protection is eroded. Ingestion of food or antacids is known to reduce the effects of acidic digestive juices on the gastrointestinal lining with eroded mucosal lining.
Transmission of SARS
Another important observation from the presentation is the 42-year-old’s smoking behavior. The blood examination indicates a higher than normal red blood cell count, which is common in habitual smokers. The smoking behavior and the current state of low hemoglobin could be useful in explaining the state of fatigue. Smoking is also related to the occurrence of stomach ulcers and esophageal regions due to reflux of acidic content and a probable association with H.pylori proliferation as suggested by Li et al. (2014).
The clinical presentation and laboratory evidence directs the diagnosis to a possible existence of peptic ulcers. Peptic ulcers occur in either the stomach lining or in the duodenum hence explaining the abdominal pain. The pains mainly occur at night and in conditions where the stomach is empty and is soothed by intake of non-acidic food or treatment with antacids. The ulceration can cause hemorrhage or interfere with iron intake thus justifying the low hemoglobin levels, low ferritin levels, low transferrin concentration, and the resultant microcytic hypochromic condition of the red blood cells. Peptic ulcers can be attributed to many causes but the most prominent one is a chronic infection by the bacteria Helicobacter pylori (H. pylori).
Peptic ulcers can be confirmed through an array or tests ranging from imaging to laboratory tests where stool and blood samples are specimens of choice. To note the presence, condition, and severity of the ulcers, an endoscopy procedure would be appropriate. Endoscopy will provide the most suitable evidence for the existence of ulcers or any other structural anomaly in the stomach and the extent of severity.
A stool test for fecal occult blood, ova and cyst, H.pylori antigen, and routine macro- and microscopic examination will also be essential. The fecal occult blood (FOB) is important in indicating the occurrence of hemorrhages in the gastrointestinal tract especially in cases of unexplained low hemoglobin levels. In the case of peptic ulcers, the FOB test would be positive. The H.pylori antigen test is critical in this case as it confirms the presence of an infection with the bacteria hence not only does it ratify the presence of peptic ulcers, but also gives its etiology and a baseline for the treatment protocol (Anand, 2017). The macroscopic examination checks for the presence of any parasite, while the microscopic examination is suitable for identification of any ova or cyst of pathogenic parasites such as Necator americanus or Ancylostoma duodenale, which are also known to cause anemia and ulcerations on the luminal walls of the small intestines. The microscopic ova and cyst test helps to rule out parasitic infection.
How SARS was Contained in 2003
Peptic ulcers are defects in the duodenum and mucosal stomach lining leading to irritation of the underlining epithelial cells by the acidic nature of fluids in the two regions. In normal conditions, the mucosa offers primary protection to the cells of the region thus preventing the scouring action of the digestion fluids produced in the stomach. An interruption of the mucosa exposes the vulnerable epithelial cells beneath leading to ulcerations. Chronic ulcerations are thought to result from the persistent action of Helicobacter pylori, which feeds on the mucosa and irritate the epithelial cells developing sores.
The occurrence of peptic ulcers results from an imbalance between the aggressive factors and the defensive factors. The aggressive factors are known to destroy the gastrointestinal mucosa and such include endogenic factors such as peptic secretions, which are known to have high acidity. Exogenous factors known to disrupt the mucosa include chronic H.pylori infection, medications such as the nonsteroidal anti-inflammatory drugs (NSAIDs), excessive smoking, chronic alcoholism and prolonged exposure to stress (Anand, 2017). Of the exogenous aggressive factors, chronic H.pylori infection and detrimental effects of NSAIDs cause greater damage to the gastrointestinal mucosa compared to the others (Anand, 2017). Factors responsible for the defense mechanism against the action of acid and pepsin are of great physiological importance even with the presence of aggressive factors. The defense mechanism can be divided into the pre-epithelial defense, which comprises of the secretion of bicarbonates and mucus, the epithelial defense including the epithelial restitution, replication, and secretion of bicarbonates, the extracellular buffers such as bicarbonates, and the post-epithelial defense resulting from mucosal microcirculation and the tissue acid-base balance. An imbalance of the two factors in favor of the aggressive factors, therefore, results in the occurrence of ulcerations due to a compromised defense mechanism.
Presence of sores leads to gastrointestinal bleeding that can be detected in the stool through a fecal occult blood test and through a blood examination for complete blood count and peripheral blood film examination. The blood examination in cases of chronic peptic ulcers reveals anemic conditions. In normal conditions, the ulcerated surfaces are expected to recover through the physiological healing processes but in conditions where the aggressive factors such as an intense chronic H.pylori infection are persistent, the peptic ulcers disease becomes chronic.
The treatment protocol for peptic ulcers disease follows various criteria depending on the clinical presentation. In the presented case, the treatment process can start by reducing or countering the effects of pepsin and acids by prescribing proton pump inhibitors to reduce acid production and allow the ulcers to heal (Mayoclinic.org, 2018). Cytoprotective agents such as sucralfate and misoprostol can accompany the proton pump inhibitors as additional prescriptions for the protection of gastrointestinal lining (Mayoclinic.org, 2018). In presence of a positive result for the presence of H.pylori infection, the condition should be treated using antibodies. The treatment of H.pylori is effected through a combination of antibiotics and the prescribed dose should be followed to prevent resistance.
Behavioral factors such as smoking and alcoholism are known to cause or enhance the occurrence of peptic ulcers. Therapeutic processes including abstinence from alcohol and cigarette smoking would be effective in helping to treat the ulcers as Li et al. (2014) confirms that cigarette smoking is highly associated with the occurrence of peptic ulcers and other gastrointestinal disorders. The patient should also modify his foods to avoid those with high acidity and instead take foods that are known to contain very little or no acidity. He should also avoid skipping meals as such will aggravate the condition by allowing the pepsin and the peptic acids to work on the stomach and duodenal walls.
References
Anand, B. (2017). Peptic Ulcer Disease: Background, Anatomy, Pathophysiology. Retrieved from https://emedicine.medscape.com/article/181753-overview
Chaudhry HS, Kasarla MR. Anemia, Microcytic Hypochromic. [Updated 2017 Dec 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2018 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470252/
Li, L., Chan, R., Lu, L., Shen, J., Zhang, L., & Wu, W. et al. (2014). Cigarette smoking and gastrointestinal diseases: The causal relationship and underlying molecular mechanisms (Review). International Journal Of Molecular Medicine, 34(2), 372-380. doi: 10.3892/ijmm.2014.1786
Mayoclinic.org. (2018). Peptic ulcer – Diagnosis and treatment – Mayo Clinic. Retrieved from https://www.mayoclinic.org/diseases-conditions/peptic-ulcer/diagnosis-treatment/drc-20354229
Medlineplus.gov. (2018). Ferritin blood test: MedlinePlus Medical Encyclopedia. Retrieved from https://medlineplus.gov/ency/article/003490.htm
SARS | Basics Factsheet | CDC. (2018). Retrieved from https://www.cdc.gov/sars/about/fs-sars.html
Smith, R., Montgomery, M., Kilroy, G., Tang, S., & Müller, S. (2015). Tropical low formation during the Australian monsoon: the events of January 2013 (paper updated July 2016). Australian Meteorological And Oceanographic Journal, 65(3/4), 318-341. doi: 10.22499/2.6503.003
WHO | SARS epidemiology to date. (2018). Retrieved from https://www.who.int/csr/sars/epi2003_04_11/en/
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