Diseases West Nile Virus, Malaria, Plague, and

¶ … diseases West Nile virus, malaria, plague, and yellow fever. Specifically, it will discuss the history and distribution of the diseases in the United States or worldwide, and compare each of the diseases based on the categories above, as to which is most important individually and overall in terms of relative impact. West Nile virus only appeared in the United States in 1999, but it has become quite a feared disease since then.

The virus is contracted in humans from infected mosquito bites, and it can be deadly in people with weakened immune systems, like children and senior citizens. The symptoms of the disease can be minor, like headaches and an insignificant fever. These can increase to confusion, muscle weakness, high fever, and severe headache ("West Nile," 2004). They usually show up 3 to 14 days after being bitten. Symptoms that are more serious include brain swelling, coma, numbness, vision loss, and disorientation but these are far less common.

Some people may not show any symptoms of the disease. Infected individuals may have severe impact on their health, and West Nile can kill those with weaker immune systems. By 2002, the disease had "exploded" across the nation, and in 2003, it showed up in mosquitoes in every state in the 48 contiguous states but Oregon and Washington. According to the Center for Disease Control (CDC), there were 9,858 human cases of the disease in 2003, and 262 deaths. This is down slightly from 284 deaths in 2002 ("West Nile," 2004).

This spread all began from one dead crow discovered in New York City with the disease in 1999. It is incredibly common in any area where mosquitoes breed and live, and so, it is incredibly difficult to control. It can also spread by blood transfusion and from mother to unborn child. There is no known cure for the virus, and for mild cases, people simply get better as the disease progresses.

The CDC is working on a vaccine against the virus, but does not expect it to be ready for several years ("West Nile," 2004). For more severe cases, treatment often includes hospitalization that might include intravenous fluids, help with breathing, and overall nursing care ("West Nile," 2004). The economic impact of this disease has been staggering. Treatment costs are not the problem; the problem is heavy spraying of infested mosquito areas in an attempt to control the disease.

There are no cost estimates for how much mosquito spraying has cost throughout the nation, but the costs must be high to many communities. This disease is on the rise in the United States and around the world, and scientists expect it to continue to grow in the United States in 2004 and beyond.

A panel of researchers note, "During 1999-2002, the virus extended its range throughout much of the eastern parts of the U.S.A., and its range within the western hemisphere is expected to continue to expand" (Campbell et. al., 2002, pg. 1). It is becoming much more common, and this can help aid public education about how to avoid the disease. Often, the host dies from the disease. It can infect a variety of animals, including birds, "horses, bats, chipmunks, skunks, squirrels, and even alligators" (Ward, 2003, pg.

B01), and so, it is quite easily spread throughout the animal kingdom, which is one reason the disease can spread across a continent so quickly. The social impact of the disease is difficult to measure, but outdoor activities are often impacted during the months the disease makes its' appearance (June through October, with a peak in September) (Ward, 2003, pg. B01). In areas that commonly support mosquitoes, residents are urged to stay inside during these months, or apply an insect repellent containing DEET (N, N-diethyl-meta-toluamide), according to the CDC.

The easiest way to avoid the disease is to avoid mosquito bites, and so, the CDC recommends draining standing water in areas where mosquitoes breed, and around the home. West Nile virus is frightening because it can spread so quickly and because it is often difficult to detect. Malaria is a disease making a comeback in the world. It was thought to have virtually disappeared, but because of concerns over pesticides and spraying to eradicate mosquitoes, the disease is common again, especially in Africa.

Malaria, like West Nile, is contracted from infected mosquitoes (usually females). The mosquitoes contract the disease from the blood of infected persons they bite ("Malaria," 2004). One of the problems with control is that mosquitoes have developed resistance to the malaria parasite, and so they pass on the disease without succumbing to it (Tenenbaum, 2002, pg. 760). The symptoms of the disease include alternating fever and chills. "Malaria may also cause renal or pulmonary failure; cerebral malaria, which usually afflicts children and pregnant women, can cause coma, generalized convulsions, and death" (Tenenbaum, 2002, pg. 760).

Clearly, the severe symptoms of malaria can cause serious impact on the health of the individual. The most serious impact is of course, death, but malaria is a silent disease, which makes it all the more dangerous. The malaria parasite can live in a person for years undetected if it is not treated effectively, or with the right drugs. The CDC notes, "Two types of parasites [...] have dormant liver stages that can remain silent for years.

Left untreated, these liver stages may reactivate and cause malaria attacks ("relapses") after months or years without symptoms. Another type, [...] if left untreated, has been known to persist in the blood of some persons for several decades" ("Malaria," 2004). Obviously the fear of malaria returning, or infecting others with infected malarial blood is a serious impact on the individual with malaria. Infection is extremely common in areas where the disease occurs.

Thought to be eradicated in the United States for decades, there were 1,337 cases of malaria and eight deaths in the U.S. during 2002 ("Malaria," 2004). In other countries around the world malaria is the leading disease causing death. One writer notes, "Today, malaria is resurgent in many tropical regions, especially Africa. According to the World Health Organization, each year it infects more than 300 million people and kills at least 1 million, mostly children" (Tenenbaum, 2002, pg. 760). There is no vaccine against malaria, but it can be treated effectively if caught early.

There are malaria pills travelers can take to avoid contracting the disease if they travel to malaria-prone destinations. There are several different types of drugs to prevent and treat malaria, and the best one for each individual should be discussed with a health professional. Clearly, the economic impact of malaria is staggering, considering the vast number of victims it claims every year around the world.

While many of the worlds' poor simply die at home of the disease, many more are hospitalized with the disease, and the costs include treatment, medication, blood transfusions, and more. In addition, there is the cost of spraying to attempt to eradicate the mosquitoes that carry the disease. The costs for medication and prevention are quite low compared to the cost of treatment and eradication.

The CDC notes, "The average cost for potentially life-saving treatments of malaria are estimated to be U.S.$0.13 for chloroquine, U.S.$0.14 for sulfadoxine-pyrimethamine, and U.S.$2.68 for a 7-day course of quinine" ("Malaria," 2004). Many third-world countries simply do not have the funds to successfully treat or eradicate the disease, and so, their citizens, especially children, continue to die from the disease. This disease is spreading around the world, and each year seems to see more suffering and death due to the disease.

The CDC states, "In areas of Africa with high malaria transmission, an estimated 990,000 people died of malaria in 1995 - over 2700 deaths per day, or 2 deaths per minute" ("Malaria," 2004). These numbers are difficult to comprehend, but they show that malaria is one of the deadliest diseases on the planet. The implications are clear. Malaria can live undetected for years, and is a killer, especially of children. It must be controlled and eradicated to keep it from killing even more, and it must be eradicated soon.

The plague is a frightening disease because everyone seems to know the story of the "Black Death" that swept through Europe in the 1300s, killing millions of people. The plague may not be as prevalent today, but because of its' long history, it is probably more frightening to people than many other deadly diseases. The most common form of the plague is the bubonic plague, and it is contracted from the bites of infected fleas that live on infected rats or other rodents.

It can also be contracted by direct skin contact of infected tissues, so handling a dead animal with the disease can transmit the disease in some cases, and treating sick patients can also transmit the disease. Unfortunately, the pneumonic form of plague can also be contracted from inhaling droplets from an infected person's cough or sneeze. The CDC notes, "Plague is characterized by periodic disease outbreaks in rodent populations, some of which have a high death rate.

During these outbreaks, hungry infected fleas that have lost their normal hosts seek other sources of blood..." ("Plague," 2004). The first sign of plague is a hot, swollen, and painful lymph node called a "bubo." The swollen node is often accompanied by fever, headache, and exhaustion. These symptoms usually begin about two to six days after the person is exposed ("Plague," 2004). The impact on the health of the individual can be fatal if the disease is not treated in time.

In addition, the patient must be isolated because the disease is so contagious, and this adds to the impact on the patient and the family. Luckily, the plague is not nearly as common as it was in earlier centuries. However, plague still exists in the world, and small outbreaks do occasionally occur. In 1995, there were 2861 cases of the disease reported worldwide ("Plague," 2004).

Clearly, the plague is not the scourge that some of the other infectious diseases are, but it is more frightening to more people because they know more about it, and the buboes are so frightening. There is a vaccine for the plague, but because the cases are so isolated, it is no longer available in the U.S. Antibiotics, including streptomycin or gentamycin are effective in the treatment, and so are several other antibiotics.

Early treatment of the disease usually ensures recovery, but one in seven people infected will usually die of the disease ("Plague," 2004). Research has shown that some people are immune to the plague. One scientist "discovered that those who were spared had an abnormal version of a gene known as CCR5-delta 32. This mutation provided them with protection against the plague" (Boston, 2002, pg. D03).

Because of the implications of this finding, researchers are now studying why this mutation occurs, and if similar mutations can protect against other deadly diseases, such as HIV / AIDS. Because of continued study, scientists also have come to understand why the plague can suddenly occur and then disappear, too. The simple answer is plague pathogens can see an opportunity to explode and capitalize on it (Wills, 1996, pg. 47). Thus, the plague and its' study have given us more understanding of how diseases develop and flourish.

The economic impact of this disease is slight because of its' minor occurrence around the world. Usually only 1,000 to 2,000 cases are reported a year. Prevention of the disease is next to impossible according to the CDC, and so, most areas where plague occurs rely on educating the public to watch out for plague-prone animals, such as ground squirrels, voles, prairie dogs, and other wild rodents. Plague-infected fleas can quickly relocate to domestic animals, so it is best to keep pets indoors if these rodents live in the area.

Plague-prone areas also attempt to control rodents in populated areas. Often, plague kills the host animal, and this is another source of infection. The social impact, in fact most impacts of the disease are slight, because it has effectively been controlled in the world. Plague does not even occur in Australia and Europe, and as reports show, there are very few cases reported each year in the United States. Plague is still in the world, but it is a good example of how a disease can be eradicated effectively.

The effort put into controlling the plague can now be turned to other, more deadly diseases. Yellow fever is another disease that has effectively eradicated in the world, and the early control of malaria came because of the attempt to control yellow fever (Wills, 1996, pg. 161). Like the plague, many people fear yellow fever because it killed so many before a vaccine was discovered and the eradication of infected mosquitoes took place.

Yellow fever is common in the tropics, it killed many travelers and explorers in the 18th and 19th centuries, and so, it became quite well-known to people. Yellow fever, like malaria and the West Nile virus, is contracted by the bites of infected mosquitoes. The heaviest time of contraction is during the rainy season in areas where the disease exists. The symptoms of the disease include symptoms resembling the flu, such as vomiting and headache, to "severe hepatitis and hemorrhagic fever" (Barwick, et. al., 2004).

Other symptoms continue to develop as the disease develops, which include a slowed pulse, bleeding gums, and bloody urine ("Communicable," 2004). These symptoms usually develop within three to six days after exposure to the disease. The name yellow fever comes from the hepatitis symptom, which can turn the patient's skin a yellow color. The impact on the health of a person infected with yellow fever can be negligible to death. The disease still occurs most commonly in Africa, where the death rate is less than 20% in reported cases.

However, in five cases between 1996 and 2002 in the United States and Europe, where travelers contracted the disease and returned home with it, all five cases were fatal ("Barwick, et. al., 2004). Yellow fever often goes unreported, and so the true figures for the disease and its death toll may never be known. There is a cure for yellow fever, and that is one reason that it occurs so infrequently. A vaccine was developed that effectively protects the patient for ten years or more against the disease.

Vaccinations are required for anyone traveling to an area where the disease is still prevalent. The vaccine does cause an adverse reaction in some patients. The CDC notes, "Yellow fever vaccine generally has few side effects; fewer than 5% of vaccinees develop mild headache, muscle pain, or other minor symptoms 5 to 10 days after vaccination" ("Yellow Fever," 2004). Some people should not be inoculated, including pregnant women and children less than 9 months of age.

The economic impact of the disease is fairly negligible, since it is much less common than many other of the infectious diseases discussed here, except for the plague. The status of the disease today looks very favorable, and if more people in Africa and South America can be inoculated, the disease might be eradicated almost entirely, as the plague has been. Unfortunately, the virus does seem to be growing in Brazil and Peru (Barwick, et. al., 2004).

However, usually one a few hundred cases are reported each year, so the disease does not show signs of violent increase, as malaria does. The social impact of the disease mostly affects travelers to certain areas who might contract the disease. Clearly, those travelers who contract it face a greater risk of death, and the statistics for Europe and the United States show. However, the actual likelihood of contracting the disease is quite low. The CDC notes, "Based on data for U.S.

travelers, the risk for illness in a traveler due to yellow fever has been estimated to be 0.4-4.3 cases per million travelers to yellow fever-endemic areas" (Barwick, et. al., 2004). Clearly, the incidence of the disease is low, and travelers who receive vaccinations should be more than safe from the disease. Yellow fever seems benign now, but just a century ago, it was still rampant in tropical areas of the world. The disease shows what concentrated research and control can do, but it also shows something else.

Yellow fever has for all intents and purposes has disappeared, but another quickly spreading disease has taken its place - West Nile virus, and the same insect spreads it. This shows that even though we eradicate one disease, there are others constantly developing. The more we learn about control and eradication from diseases like yellow fever, the more we can hope to find answers to West Nile, and the other diseases waiting in the wings. Each of these diseases is serious, and can be deadly to some individuals.

West Nile virus is frightening because it spreads so quickly, and affects such a large number of birds and animals. The plague has been around for so long it is incredibly frightening, and can decimate huge numbers of the population if left untreated. Yellow fever can be extremely devastating, even though it only occurs in Africa and South America today. The thing that is important to recognize about all these diseases is insects that are difficult if not impossible to eradicate and control spread them.

This is why these diseases continue to spread across the globe, and this is one reason these diseases are so very serious. Obviously, if these diseases got out of control, the social impact could be devastating. Thousands, even millions of people could die, and the population of the world could be devastated. However, each of these diseases is a lesson in treatment and control.

As man has learned more about each deadly disease, they have been able to control some of them, and that control has eventually led to the control of other similar diseases. For example, the attempt to control malaria.