Virus World and Evolution of Cells - Assignment Example

Scenario  John and Linda are paramedics working in a rural area. Today’s shift has been particularly busy and they are both looking forward to a relaxing evening once the shift is over. While returning from the hospital after dropping off a patient from a nursing home, they are dispatched to a private residence for the report of a child that is semiconscious and having difficulty breathing.  They arrive at the home and are directed to an upstairs bedroom where they find a male child, 4 years old weighing approximately 14 kg in bed. Patient history is as follows:  Chief Complaint Semi-conscious with difficulty breathing  History of Present Illness 3 day history of flu-like symptoms with fever, headache and some joint stiffness  Past Medical History Normal childhood illnesses  Medications No prescription medications – paracetamol for last two days for fever and pain  Allergies None known  The paramedics conduct their primary and secondary assessment of the child and have the following findings:  Upon physical examination the paramedics find no evidence of physical trauma, however, the pulse is weak and rapid, auscultation (listening with the stethoscope) of the lungs demonstrates mild course crackles in the lung bases with a breathing rate of 40 beats/min and the skin is flushed. Electrocardiograph (ECG) demonstrates tachycardia (fast heart rate). The child remains semi-conscious.  John and Linda put on gloves and initiate supportive care and treatment for this child. They proceed with the following treatment:  Airway – insertion of a nasopharyngeal airway  Breathing – application of a non-rebreather oxygen mask  Circulation – location and cannulation of an accessible vein for fluid hydration and drug administration.  The treatment is completed and the paramedics carry the child down to their stretcher and out to their vehicle. John goes into the back of the ambulance with the child and Linda climbs behind the steering wheel and drives to the hospital. At the hospital the paramedics perform a handover to the medical staff providing the history and the results of their examination.  The medical officer, Dr. George, makes enquires of the mother confirming the initially supplied patient history. Dr. George notes that the mother is periodically coughing and asks her about her own health. The mother replies that she had been ill last week and she thought it might have been flu as her joints were achy but that she did not see the doctor as she was too busy at work. She self-medicated throughout with cold and flu tablets from the local chemist. She now feels much better but still is periodically coughing. The mother is 22 years old. Dr. George has admitted to the hospital several very unwell patients with flu like symptoms and a cough in the past few days aged between 8 and 20 years, one of whom is currently semi-conscious and in intensive care.  The nursing staff, Sue and James, repeat the observations for body temperature, blood pressure, pulse, breathing rate and level of consciousness whilst also transferring the child from the ambulance equipment to the hospital’s breathing support equipment and ECG monitor. James puts on gloves and checks that the cannula placement and drip line have remained patent during the transfer. Dr. George checks the child for neck rigidity and reactions to bright light. He then takes a blood sample and orders a full blood count and antibody markers as well as a chest X-ray and spinal tap for a cerebrospinal fluid (CSF) sample. He also writes a request for the fluid hydration to be continued and prescribes an antipyretic to lower the child’s temperature. Dr. George is looking to differentiate between influenza and meningitis. Dr. George considers prescribing antibiotics as a precautionary measure for meningitis whilst awaiting the results of the diagnostic tests.  Dr. George then proceeds to take a more detailed history of where the child has spent the last couple of weeks and who he and the mother have been in contact with.  Question 1 (10 marks)  a. Describe how viruses and bacteria differ  Viruses are small particles that are not considered alive. They can only replicate inside a living cell where they use the “machinery” of the living cell to replicate their genetic material and structural proteins (Koonin et al. 2006). Viruses are constructed from a genetic material (DNA od RNA) that is encapsulated by protein capsule that protects the genetic material. Some viruses also have lipid coating that surrounds the protein capsule when the virus is outside a living cell (Lawrence et al. 2009). Viruses are usually very small and can’t be seen by optical microscope. Antibiotics have no effect on viruses and in many cases treatment is only supportive, but there are several antiviral agents that are effective to some viruses (Magden et al. 2005) (Witthöft et al. 2007). Bacteria on the other hand are single cell organisms that are able to live and replicate using their organelles. There are bacteria that constitute the normal flora in the human organism, located in the gut, respiratory system, skin etc. It is estimated that there are 10 times more bacteria in the human organism than there are human cells (Sears 2005). Other bacteria are pathogenic and can cause different diseases in humans, but sometimes bacteria in the normal human flora can cause infection (in weakened immunity, when they invade an organ where they are not normally found etc.) (Finlay and Falkow 1997). Bacteria are susceptible to antibiotic treatment and there is a wide range of antibiotics available for treatment of wide range of bacteria that affect different processes in the bacteria (Poehlsgaard and Douthwaite 2005) (Yonath and Bashan 2004). b. Why is it important to this scenario that you be able to distinguish between a viral and bacterial infection?  The child obviously has signs of infection and inflammation of the respiratory tract: fever, malaise, headache and some joint stiffness, tachipnea, the skin is flushed, auscultation reveals mild course crackles in the lung bases and other flu like symptoms (Eccles2005). The signs of infection can be caused by viral or bacterial pathogen. Differences in symptoms between viral and bacterial respiratory infection are mild and cannot be differentiated on the basis of the clinical appearance (CDC 2009). However it is important to differentiate if the causative agent is a virus or bacteria because of several reasons: - Viruses are not susceptible to antibiotic treatment and only supportive treatment is necessary in most cases and the disease resolve itself without any specific treatment. Antiviral drugs are effective if started before or early after the first symptoms of viral infection but they should be given in severely ill patients because they can reduce the duration and severity of the disease (CDC 2007). - Bacterial infections usually require antibiotic treatment and if not treated they can progress to more severe disease and death. c. How will the characteristics of these microbes affect the treatment chosen for the child and why?  Depending if the pathogen is a virus or bacteria the treatment chosen by the doctor may be more or less effective. If the pathogen is bacterial than antibiotics will take effect and the condition of the child should be rapidly improving. If the pathogen is viral antibiotic treatment will have no effect. This is why Dr. George is doing laboratorial and microbiological investigations in order to differentiate the etiological agents. Question 2 (7.5 marks)  a. Why does Dr George proceed to obtain details of the contacts that both the mother and child have had with other people in recent weeks?  Dr. George is obtaining details about the contacts that both the mother and child had for several reasons. As we can see in the case study Dr. George already has admitted to the hospital several patients with flu like symptoms and a cough in the past few days aged between 8 and 20 years, one of whom is currently semi-conscious and in intensive care. Viral respiratory infections like influenza are very contagious and are easily transmitted from one person to other with saliva droplets during speaking, talking, coughing etc. Because of this viral infections are prone to infect large numbers of people during the flu season (colder months in the year because influence virus is sensitive to heat). Information of contact with a person with flu-like symptoms can be a very significant sign that probably the infection is viral. b. Why may the occurrence of this infection be reported to an epidemiologist?  In the case if the child is infected by influenza virus dr. George will have to report this disease to the epidemiologist as a measure for preventing flu epidemic. This measure is accepted by almost every country in the world in order to monitor the incidence of infectious diseases, including influence and other infective respiratory diseases (Freund et al. 1989). Question 3 (6.5 marks)  Often fomites are involved in the transfer of infectious agents.  a. Define the term fomite and list three fomites that may be contaminated in this scenario  Infectious diseases have the ability to be transferred through fomites. Fomite is any object or substance that is capable to carry the infectious agents and transfer the agents to another person. As we know the mother was ill several days before the child so there is a high probability that the disease was transmitted from the mother to the child (Bean et al. 1982). Example of fomites that may be the source of infection in the above mentioned case may be the clothes of the mother that have been contaminated with a virus or bacteria. The kitchen towel is another fomite that may have transferred the infective agent to the child. Another example that may have been involved in this case may be: clothes, kitchen accessories like handle of the refrigerator, handles of the doors, some other items that are used by all members in one family like toothpaste tube, toilet paper, key chain etc. b. Identify and discuss what procedures should be put in place to avoid contamination of fomites that can lead to further disease spread  There are many measures that can reduce the mmount of contamination of fomites. First step is adequate healt information and health promotion. Patients and general public must be informed about the routes of transmission and the significance of fomites in transmitting infective agents. In private homes usage of personal toothbrushes, towels, maintaining high levels of hygiene, using adequate cleaning products that have antibacterial or antiviral qualities, frequent washing of the hands and other measures that will prevent from contaminating the household objects and also prevent transmission of the infective agent from the fomites to the mouth, eyes, nose etc. (Merrill and Timmreck (2006). Question 4 (6 marks)  a. Identify the events in the scenario that have the potential to cause secondary infections for the child; and  Influenza and other viral infections of the respiratory tract are commonly complicated with bacterial infection. There are studies that show that viral respiratory infections predispose to developing bacterial superinfection (McCullers 2006). Bacterial infection is usually manifested as a second peak of the fever and worsening the symptoms after the clinical picture of the disease showed some improvement (Ravindra et al. 2008). It is found that approximately 30% of all community acquired pneumonia that was confirmed by laboratory findings are viral and bacterial coinfections where Streptococcus pneumoniae is the most commonly found cause of bacterial superinfection (Lim et al. 2001) (OBrien et al. 2000). Other bacterium that commonly causes bacterial superinfection after influenza or other viral respiratory infection is Neiserria meningitidis. There are studies that suggest that Influenza virus enhances the adhesion of N Meningitidis bacteria to the respiratory epithelial cells, therefore promoting entering the blood, causing meningitis and other complications (Marie-Anne et al. 2009). As we can see dr. George was checking for meningeal signs (stiff neck), and condition of semi-conscious state of the child may be caused by bacterial meningitis. This is another reason why dr. George mite prescribed antibiotics, as a preventive measure until the laboratory findings are completed. b. Identify how the ambulance and hospital staff might avoid cross infection  Based on the above discussion we can safely conclude that the child propably has viral infection with a possibility for a bacterial superinfection. Viral respiratory infections especially influenza are highly contagious and the ambulance and hospital stuff should have used preventive measures to avoid infection and contamination. Some of the measures they could have used are: wearing a robber gloves when working around the patient, wearing face mask, correct disposal of the syringes, needles and other disposable material that they used, cleaning with some antibacterial and antiviral chemical disinfectants the ambulance vehicle, medical table and other medical inventor that got in contact with the patient or patient’s secretions etc. (Ray et al. 2006). Question 5 (10 marks)  Chemical disinfectants are also often used to control the spread of infectious agents. Many of these chemicals are corrosive or are cationic detergents.  a. Explain what the term cation means and how atoms can become cations  Cations are positively charged atoms or molecules that have more positive than negative charge. They can be monoatomic (like Na+, Fe2+ etc) or polyatomic or molecular cations (for example NH4+). Cations are produced when an atom or molecule loses one or more electrons in the valence shell of the atom. They are highly reactive and can receive electrons from anions (negative charged atoms or molecules) producing salts, acids or other more or less corrosive substances (Kenneth et al. 2009). b. Cations are usually reactive chemicals. Explain why  Cations are positively charged atoms or molecules that lack one or more electrons in their valence shell, which is the outer most orbital of the atom. Because of this they are highly reactive and can receive electrons from ions which have one or more additional electrons in their valence shell, therefore forming covalent bonds. This makes them very reactive and corrosive substances that should be managed with cautions (Kenneth et al. 2009). c. Explain what the term corrosive means  Corrosive substance is a strong acids or bases or high concentrations of weaker acids or bases. These corrosive substances are able to breach the skin integrity by reactions of etherification, aldol reactions, amide hydrolysis and other reactions where they catalyze the hydrolysis of the fats and other esters. Corrosive acids and bases can also catalyze hydrolysis and denaturation of proteins but also other organic tissues like bone, hair etc. (Mozingo et al. 1988). d. Explain why corrosive substances are harmful to human tissue  Because of the above characteristics of the corrosive substances they can cause damage and destruction of organic tissues. They can cause severe irritation, chemical burns, necrosis and other more severe damage on the skin (Mozingo et al. 1988). When inhaled can cause severe respiratory distress and even organ failure if inhaled in higher concentrations (Fulton and Hoffman 2007). When ingested can cause severe damage of the esophagus, stomach, intestines but can also slter normal PH levels in the organism and can cause systemic effect also (Howell 1986). References: Koonin EV, Senkevich TG, Dolja VV. The ancient Virus World and evolution of cells. Biol. Direct. 2006;1:29. doi:10.1186/1745-6150-1-29. PMID 16984643 Lawrence CM, Menon S, Eilers BJ, et al.. Structural and functional studies of archaeal viruses. J. Biol. Chem.. 2009;284(19):12599–603. doi:10.1074/jbc.R800078200. PMID 19158076 Magden J, Kääriäinen L, Ahola T. Inhibitors of virus replication: recent developments and prospects. Appl. Microbiol. Biotechnol.. 2005;66(6):612–21. doi:10.1007/s00253-004-1783-3. 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