Yellow Fever Disease - Coursework Example

Yellow Fever Disease Yellow Fever is a fatal disease that starts like fever but advances with time to causation of yellowing of the victim’s eyes as well as jaundice. In connection to this, Shmaefsky (11) asserts “the disease is identified by a famous fever response of very high body temperatures ranging from 39.4 to 40.50c.” Cefrey (5) further defines yellow fever as a disease that results to the cracking of lips, oozing of blood from the nose and mouth and eventually the death of its victim (Cefrey 5). According to Shmaefsky, yellow fever is categorized as a vector-borne viral fever. He justifies his assertion by stating that the illness is spread from one host to another by agents that carry the virus. The virus that carry this disease belongs to the family of viruses referred to as flaviviridae. However, “some medical professionals consider yellow fever as viral hemorrhagic fever or VHF” (Shmaefsky 11). This is as a result of the disease having the potential to destroy various body organs. According to Cefrey, the disease is spread by mosquitoes and is most prevalent in some parts of Africa as well as South America. Cefrey further claims that yellow fever is not curable, but can be prevented through use of yellow fever vaccine. Yellow fever derived its name from the effect it causes on a victim’s skin; the disease results to one’s skin turning yellow along producing fever. Skin yellowing however is as a result of jaundice that is caused by the damage of the liver after the infection with the virus. Yellow fever is also referred to as by other names. For instance, throughout history the disease was referred to as black vomit and vomito negro. Some people also called the disease sylvatic fever or Yellow jack. Yellow fever was called black vomit or vomito negro because of the black vomit the infected people produced. Sylvatic fever derived its name from the perception that the disease is prevalent in areas rich with trees, such as jungles. The name yellow fever was invented by the newspapers because the disease was thought to be as destructive as enemy troops. According to Shmaefsky (13), there are three classifications of yellow fever. The three types however have the same signs and symptoms. The three types of the diseases are intermediate yellow fever, urban yellow fever as well as jungle yellow fever. Intermediate yellow fever is common in humid grassland areas, and it is thought to be spread by mosquitoes that carry it from the monkeys to human beings. Unlike intermediate yellow fever, jungle yellow fever takes place in rural areas, and it is carried from one human to another by mosquitoes residing in tropical jungles. Urban yellow fever is common in cities and is transmitted from one human to another by mosquitoes that reside in water bodies near homesteads, other types of buildings, as well as fields. Despite its occurrence in different areas, the diseases are indistinguishable, and as a result of this, they may overlap in areas manifested with different types of mosquitoes. Information on how the disease is spread is also provided in Figure 5. History of yellow fever Yellow fever is a very old (ancient) human disease that affected societies before people knew anything about the causation of infectious diseases. Early civilizations also knew nothing about the essence of observing hygiene along knowing nothing about genetics and microorganisms, so they did not know what caused the disease. It is possible that the majority of the people thought of the disease as a misfortune or some sort of disease that resulted from the consumed diet. In early history, majority of the people also confused the disease with other types of fever. As a result of this, any documentation about the disease before 1700s was meaningless and inaccurate because of two main reasons: first, the confusion of the disease with other types of diseases, and second the lack of knowledge concerning the disease by medical personnel. Early Egyptian information in medical documents provides a variety of diseases with the characteristics of yellow fever. These documents however provide the actual information about the diseases. However, the descriptions provided in the documents overlapped with the known information about other diseases of that time. More on the areas where the disease was prevalent is shown in Figure 4. According to Shmaefsky (14), the accurate information about yellow fever was documented in the Yucatan, Mexico, in early 1648, when majority of the people developed conditions that best matched the disease. “It was believed that the disease found its way into Mexico from the Bahamas after people reported a similar disease that spread throughout the Caribbean islands” (Shmaefsky 14). At the early times, the disease was very severe in European settlers than among the Africans that were brought to America through slave trade. As from 1600s to 1800s, yellow fever was discovered in the majority of the coastal areas of Europe, North America as well as South America. As from that identification, it is evident that the disease had started to affect many people. However, it was discovered that the disease was less severe to the Africans. The spread of yellow fever was not understood until the late 1880s. Medical professionals noted that the yellow fever was common in areas manifested by malaria. Malaria is one of the deadliest diseases. However, both malaria and yellow fever were not thought to be contagious through human contacts like many other infectious diseases. They were thought however to be spread by vapors produced by water or by getting in contact with water. This perception was enhanced by the occurrence of the diseases mostly in areas with water bodies. The first attempt to find out the spreading agent of yellow fever was made by a Cuban scientist referred to as Carlos Finlay in 1881. Finlay decided to study the mode of spread of the disease in order to combat the number of deaths in the lower Mississippi that resulted from the disease in 1879. According to Shmaefsky, Finlay believed that a specific mosquito from the tropical regions was responsible for the spread of the disease through its bites. Finlay thought of this because the mosquito was very prevalent in areas that were well known to contain the disease as well as in areas with water bodies. Despite all his arguments, however, Finlay did not manage to prove his hypothesis through carrying out any experiment. According to Shmaefsky, Finlay might have feared to carry out an experiment with the infected persons. Pressure to find the root cause of the disease was enhanced by the Spanish-American war that had taken place in Cuba and Puerto Rico in early 1898. Majority of the soldiers were losing their lives more to the disease than the injuries they underwent in the war. The extensive loss of manpower to the disease made the Surgeon General of the United States to call a group of medical researchers to determine the main cause of yellow fever. This effort was enhanced by the leadership of army surgeon Walter Reed. Reed was assisted by Aistides Agramonte, Jesse Lazear as well as James Carroll, who were all surgeons. They went through many ideas including Carlos Finlay’s hypothesis. In carrying out their study, Reed’s team used military volunteers. Among the tests, they carried out include whether the disease was spread through direct contact. This was managed through having volunteers sleeping on the bed together or volunteers wearing clothing from yellow fever patients. The volunteers were kept away from any vector. The result of the experiment showed that none of the volunteers got the disease, and as a result of this, it was evidenced that the disease did not spread through body contact. In another experiment, Reed’s team chose a group of volunteers and exposed them to mosquitoes that had fed on the remains of people infected with the disease. The volunteers got the disease, and as a result of that, the idea that the disease was spread by mosquito bites was accepted. Despite his success in finding the spreading agent of the disease, Reed’s human experiment gained a lot of criticism. Majority of the people from the scientific community were displeased by his intentional use of human experiments. In connection to this, it is a continuous self-experimentation on the disease that Jesse Lazear lost his life in 1900. Despite the controversies associated with the disease, Major William Gorgas carried out a mosquito eradication program that significantly led to the reduction of yellow fever in Cuba in the early 1900s. Today, mosquito control is used as the main strategy for controlling the spread of diseases carried by mosquitoes. Many countries have adopted comprehensive mosquito control measures that are well outlined by the Centers for Disease Control and Prevention, as well as World Health Organization. Vaccination programs are also globally encouraged so as to prevent the incidence of yellow fever in areas with areas populated with uncontrolled mosquitoes. As a result of the measures put, yellow fever is considered currently as a rare disease. However, in the 1900s the disease was almost becoming a major plague in warm regions all over the globe. More information on how the disease spreads is provided in figure 2. Reasons for choosing the topic I was interested in the topic Yellow Fever Disease because of the close relationship it has with other viral diseases. Its mode of transmission was at first confused with the current mode of transmission of Ebola. As from the history I have provided above, majority of the people thought the disease was spread from one person to another through body contact or contact with the clothing of the patients of yellow fever. However, the research carried evidenced that the disease was transmitted from one person to another via mosquito bites. The symptoms of the disease are also different from those portrayed by Ebola patients. For instance, the signs of symptoms of Ebola include fever, vomit (but not black vomit), and hemorrhage as well organ failure. Thus, the color of the vomit can aid one to differentiate Ebola from yellow fever. From the similarity of the severity of the two diseases, I am convinced it will be easy for people to take necessary measures against all viral diseases. Cause and diagnosis of yellow fever The yellow fever is caused by yellow fever virus. According to Pelczar (724), the yellow fever virus belongs to the genus Flavivirus and family Flaviviridae.” The virus is 38nm wide with an icosahedral capsid that is 30nm in diameter enclosing the single-stranded RNA. The icosahedral capsid is enclosed in a tight-fitting lipid envelope. The virus also has a short spiky surface projection. The virus has the capability to replicate within the tissues of mosquitoes as well as the tissues of primates and humans. The yellow fever virus is regarded as an arbovirus, a name that defines its mode of transmission. A mosquito that carries this virus transmits the disease horizontally to monkeys and humans as well as vertically passing the disease to its eggs. In other words, the mosquito is the active reservoir of the disease-causing virus. The infectious portion of the virus however is the nucleic acids that contain one positive strand. The virulence factors of the virus include the start of the replication of the virus at the sight of the carrier, mosquito, and the entry of the virus into a cell by aid of receptor-mediated endocytosis, and the involvement of the charged proteins of the nucleocapsid in the binding of the RNA to the cellular membranes. Children are the ones that are most affected by the disease maybe because of lack of vaccination. The disease also occurs in unvaccinated men who expose themselves to mosquitoes through working in the forests. Figure 3 provides some information on the causing agent of yellow fever. The development of the best methods of diagnosing yellow fever has become one of the key public health priorities in the control and management of the viral diseases. According to Banatvala, Griffiths, Pattison, Schoub, and Zuckerman (537), “the IgM antibody capture ELISA has become a test of choice for rapid serological diagnosis of yellow fever virus infection.” Cross-reactions often occur but IgM antibody outdoes the reaction by being higher than the yellow fever. Immunofluorescence tests on infected cells as well as acetone-fixed aid in detecting IgG and IgM present in a patient’s sera. The classical techniques like haemagglutination-inhibition (HI) and neutralization tests are still used in the surveillance as well as diagnosis of yellow fever. According to Banatvala et al., (537), isolation of the virus is often carried out in specialized laboratories by intraperitoneal inoculation of suckling mice. Viral RNA is confirmed if it is in the blood by use of polymerase chain reaction (PCR). A liver biopsy is also carried out to confirm the presence of the virus in the blood. However, liver biopsy is often contradicted with the bleeding of the live in those suffering from the disease. In most occasions, liver biopsy is carried out after a victim of the disease has died. Symptoms of yellow fever disease The signs and symptoms of the yellow fever disease take place in three stages that is, the early stage, brief remission stage as well as the yellow stage. The virus appears asymptomatic in the early days of the infection. The early symptoms begin to appear at an early stage. Most infected people recover after showing the early stages symptoms before the disease advances to the yellow stage. However, approximately one person in a group of 17 does enter to highly toxic stage of the disease. Since initial symptoms of the disease are common to other viral diseases, the disease poses a great challenge to health personnel. As a result of this, diagnostic tests are recommended in order to protect the patient from entering the yellow stage. The signs and symptoms of the early stage include: · Fever · Changes in pulse · Vomiting · Bloodshot eyes · Muscle pains and headache · And reduced urine The signs and symptoms of the Brief Remission Stage are not identical because the infected person appears asymptomatic and may consider oneself as healed. The signs and symptoms of the Yellow Stage which lasts for 3 to 9 days include: · Jaundice (liver inflammation, yellowing of both the skin and the eyes) · Weakness · Fever · Black vomit · GI bleeding · Delirium · Renal failure · Coma · Death Some of the information on the signs and symptoms of the yellow fever are also provided in the Figure 2. Treatment of yellow fever disease Despite production of many diverse drugs, it is evident that none has proved effective in the treatment of yellow fever. Management of the disease calls for supportive care on patients showing symptoms as well as those with organ failures. According to “Centers for Disease Control and Prevention” (“Centers for Disease Control and Prevention” 5), “patients with multisystem organ involvement likely require critical-care support with possible mechanical ventilation or hemodialysis.” Rests, fluids as well as nonsteroidal anti-inflammatory drugs and acetaminophen have the potential of relieving milder symptoms of the disease. Aspirin should not be used as one type of medication because of hemorrhagic complications associated to it (“Centers for Disease Control and Prevention” 6). Cure for yellow fever disease Despite the extensive research on a cure for yellow fever, it is evident that there is no cure for the disease. However, the disease can be controlled. Preventive measures of the disease include immunization as well as effective control of the vector. Some of the best methods of controlling the vector include avoiding mosquito bites by using insect repellants such as those made of DEET and picaridin, wearing clothing that can prevent mosquito bites, and being aware of the time when the mosquitoes are very active. It is also advisable for children below 9 months to be vaccinated against yellow fever in order to prevent the impact of the disease. Figure 1 expounds on the prevention of yellow fever. Conclusion In conclusion, yellow fever disease is a disease that is caused by a virus that belongs to the genus Flavivirus. The carrying agent of the disease is a mosquito. The infectious portion of the virus however is the nucleic acids that contain one positive strand. Yellow fever disease is historically known as a very severe disease; it was a pandemic disease in the 1900s. There are three types of yellow fever: the jungle yellow fever, intermediate yellow fever, and the urban yellow fever. ELISA is used in serological diagnosis of yellow fever virus infection. Immunofluorescence tests on infected cells as well as acetone-fixed aid in detecting IgG and IgM present in a patient’s sera. “The symptoms of the disease vary from a mild, undifferentiated febrile illness to severe disease with jaundice and hemorrhagic manifestations” (“Centers for Disease Control and Prevention” 5). Management of the disease calls for supportive care on patients showing symptoms as well as those with organ failures. Preventive measures of the disease include immunization as well as effective control of the vector. Works Cited “Centers for Disease Control and Prevention.” Yellow Fever Vaccine. (2010): Web. 15 Nov. 2014. < http://www.cdc.gov/mmwr/pdf/rr/rr5907.pdf> Banatvala, Jangu, Griffiths Paul, Pattison John, Schoub Barry and Zuckerman Arie. Principles and Practice of Clinical Virology. New York: John Wiley & Sons, 2004. Print. Cefrey, Holly. Yellow Fever. New York: The Rosen Publishing Group, 2002. Print. Pelczar. Microbiology:Application Based Approach. New York: Tata McGraw-Hill Education. 2012. Print. Shmaefsky, Brian. Yellow Fever. New York: Infobase Publishing, 2009. Print. Figure 1: Prevention of yellow fever Figure 2: Symptoms and signs of yellow fever Figure 3: Causing agent of yellow fever Figure 4: places where the disease is rampant Figure 5: The spreading of the yellow fever disease Read More