Table of Contents
Malaria is an infectious and life-threatening disease that is caused by a parasite known as plasmodium which is transmitted to the human body via a bite from an infected mosquito. It is more common in tropical and subtropical areas and this includes some parts of Asia, Africa and America. Every year, three hundred and fifty to five hundred million cases of malaria are usually recorded worldwide and out of this, between one and three million people die of the disease. Majority of those who die come from sub-Saharan Africa and they are mostly children. In particular, ninety percent of malaria-related deaths are recorded in sub-Saharan Africa. This disease is always associated with poverty, but it is important to note that it is also in itself a source of poverty and a major impediment to economic growth (Kuby, 22-23).
There are five species of the plasmodium parasite that can affect human beings. The most severe form of the malaria is caused by a parasite known as Plasmodium falciparum. Plasmodium vivax, Plasmodium malariae and Plasmodium ovale cause a milder form of the disease that is usually not fatal. The other species of the plasmodium parasite is known as Plasmodium knowlesi and it is a zoonosis that usually causes malaria in macaques. Nevertheless, it can also infect human beings but this is a very rare phenomenon (Kuby, 26).
Naturally, the parasite that causes malaria is transmitted by the bite of a female mosquito referred to as the anopheles mosquito. When an anopheles mosquito bites a malaria-infected person, it takes with it a small amount of blood which contains the malaria parasites. These parasites mature within the mosquito's body and after about one week, when the mosquito bites another person, it injects the mature parasites inside that person via its saliva. These parasites stay in the liver of this person and after a period of about two weeks or one month, or even a year or several years, they start multiplying within the red blood cells. At this point, the infected person starts exhibiting symptoms such as fever, vomiting, anemia, joint pain, retinal damage, convulsions and headache. Cerebral malaria, which affects the brain, is associated with retinal whitening. Severe cases of the disease may lead to a patient experiencing a coma or even lead to death.
There are several anti-malarial drugs that are available for the treatment of malaria. Within the past five years, the treatment of infections from Plasmodium falciparum in prevalent countries has undergone transformation that has involved the combination of drugs that contain an artemisinin component. Severe malaria is often treated with intramuscular or intravenous quinine and sometimes by an artemisinin component known as aetesunate. It is however important to note that malaria has developed resistance to several anti-malarial drugs such as chloroquine (Kuby, 27-30).
It has always been very difficult to correlate the existing facts about the occurrence of malaria in America with the epidemiological aspects of this disease in the past. Very little information is known about the early years of American occupation. The most recent publication about the history of malaria in America is entitled 'Malaria in the Upper Mississippi Valley, 1769-1900' by E. H. Ackercnecht. It is a record of a very exhaustive and comprehensive investigation on the history of malaria in America. In this publication, the writer points out the great difficulties that have always surrounded the efforts to achieve adequate quantitative information about the origin of malaria in America, and its confusion with typhoid. The author carried out a research in five states: Missouri, Illinois, Minnesota, Wisconsin and Iowa, which he thought were likely to yield the desired information. The findings from each state indicated that there was a very long epidemiological latency or interval before malaria became prevalent in the US and this is a strong assertion that malaria was not an indigenous disease in the Western Hemisphere during the Pre-Columbian times. Nevertheless, just after the close of the Pre-Columbian period, in the nineteenth century, malaria started becoming prevalent in America. Towards the end of that century, cases of malaria began to reduce but it is not exactly clear what led to this decline even though some researchers say that it is because of the role that quinine played (Kuby, 33-50).
Leishmaniasis is a disease that is caused by parasitic protozoa which belongs to the genus Leishmania and it is contracted by humans when a certain sand fly species called phlebotomine bites them.
These sand flies live in caves, holes of small rodents or even in forest areas. Even though most of the published literature concerning this disease specifies only one genus of the parasite that causes this disease in humans, a recent study carried out in the US by Galati in the year 2003 indicates that there is a new category of the new world sand flies that causes this disease (Myler, 12-15).
Most types of Leishmaniasis disease are transmitted to humans by animals but the disease can also be transmitted from one person to another. Nevertheless, human transmission can only be caused by about twenty one out of the thirty species which infect mammals. These different species of sand flies are morphologically identical but they can be distinguished by processes such as DNA sequence analysis, isoenzyme analysis or through monoclonal antibodies (Myler, 17).
The most widespread form of Leishmaniasis is called cutaneous Leishmaniasis. Another form referred to as visceral Leishmaniasis is a more serious form of the disease in which the parasitic protozoa have moved to the body's vital organs such as the spleen and the liver. The general symptoms of Leishmaniasis include the development of sores on the skin. These sores begin to erupt after several weeks or months from the time of infection. Other symptoms include anemia, liver and spleen damage, and fever and these might begin to show up several months or years after contracting the infection (Myler, 20).
Leishmaniasis is usually considered as one of the major archetypical causes of a patently enlarged spleen in the field of clinical medicine. Normally, this organ is not usually felt during the evaluation of the abdomen in a healthy person, but when a person contracts Leishmaniasis, the spleen may become bigger than even the liver in more serious cases. The four main forms of Leishmaniasis include visceral Leishmaniasis, cutaneous Leishmaniasis, mucocutaneous Leishmaniasis and diffuse cutaneous Leishmaniasis (Myler, 23-30).
Even though there is a general agreement concerning the taxonomic groupings and antiquity of Leishmaniasis among the researchers, the exact geographic location and root of its origin are widely disputed. The origin of the disease is quite unclear. Some theorists claim that it originated in Africa who migrated with it to America. Other theorists claim that it originated in America fifteen million years ago. The most recent migration of the disease is thought to be from Mediterranean nations to Latin America (Myler, 34).
It is important to note that the treatment of Leishmaniasis is still quite far from adequate because all the drugs that have been developed for its treatment are toxic to the human body and at the same time, most of them have to be used for quite a long period of time, particularly for patients with the visceral Leishmaniasis form of the disease. Nevertheless, Leishmaniasis is usually treated by drugs that contain antimony compounds such as Sodium stibogluconate and Meglumine antimonite. Other types of drugs that can be used include: Fluconazole, Amphotericin B and Pentamodine. Since the disease may sometimes cause disfigurements on the face of the patient as it is with the case of cutaneous Leishmaniasis, plastic surgery may be performed to correct these anomalies. In cases where a patient resists the viral Leishmaniasis drugs, his/her spleen is removed through a process called splenectomy (Myler, 35-50).
Chagas disease, which is also commonly referred to as American trypanasomiasis is a tropical parasitic disease that is spread by insects. This disease is caused by a parasite known as Trypanasoma cruzi which is almost similar to the African trypanosome, the causative agent of sleeping sickness. This disease is one of the major illnesses that cause problems in South America. Frequent immigration of people has also made the disease to prevail in the US. The parasite that causes this disease is usually transmitted to human beings and other mammals by blood sucking assassin bugs and other insects. This disease may also be contracted from one person to another through organ transplantation, blood transfusion, mother to fetus transmission and through ingestion of contaminated food (Miles, 42).
Patients who suffer from Chagas disease exhibit various symptoms which vary from one person to another depending on the stage of the infection.
During the early or acute stages, the prevailing symptoms are usually mild such as a local swelling at the point of infection. As the disease continues to grow, within the course of several years, severe and chronic symptoms begin to emerge. These include symptoms such as deformity of the intestines and heart diseases. If the disease is not treated, it becomes fatal. The existing drugs that are used for the treatment of this disease are quite insufficient. In addition, they are highly toxic to the human body and often inefficient. This is particularly true with the drugs that are used for the treatment of the disease at its chronic stage (Miles, 50-55).
This disease is prevalent exclusively in America. It is more common in poor areas and rural areas of Central America, South America and Mexico. The Southern part of the United States of America rarely records this disease. It is approximated that between eight and eleven people who live in Central America, South America and Mexico live with this disease but they do not know about it. The prevalence of this disease is largely augmented by the frequent migrations of people from rural areas to urban areas in Latin America and many other places in the world. Control strategies that have been put in place to prevent this disease often focus on eradicating the triatomine vector and preventing the transmission of the disease from other sources (Miles, 58).
Chagas disease occurs in two stages in human beings. These are the acute or early stage which normally occurs after a very short time from the time of infection and the chronic stage which develops after several years. The acute stage lasts for only a few weeks or months after the time of infection. In many cases, it remains unnoticed since it does not show any initial symptoms. On the other hand, the symptoms might be very mild and not unique to be discovered as symptoms of the Chagas disease. However, symptoms at this stage might include body aches, fatigue, vomiting, diarrhea, loss of appetite, development of rashes and fever. If physical examination is carried out, symptoms such as a mild swelling of the spleen and liver might be noticed. Other symptoms of this disease include local swelling at the place where the parasite entered the body and swelling of the glands. The most recognizable symptom of the Chagas disease during the acute stage is the swelling of the eyelids close to the place where the wound emerged from the bite, or where the feces of the insect dropped or were unintentionally rubbed into the eye by the patient (Miles, 60-65).
Even though the symptoms of this disease might occur during the acute stage, they usually become noticed between the third and the eighth week from the time of infection in almost ninety percent of the individuals who get the disease. If the disease is not treated at this point, the infection will persist. It is a very rare phenomenon but sometimes children with less than five years and even some adults die from a severe form of this infection, when it produces a severe inflammation of the heart or the brain muscles. The early stage of this disease might also be severe in patients who have a weak immune system. Close to ten percent of the people who contract this disease do not exhibit any symptoms in the acute stage and this result to the imprecise asymptomatic stage which is also referred to as the chronic latent stage.
Close to thirty percent of the people who contract this disease start to exhibit the medical problems that are associated with it after several years or even decades of infection. The symptomatic chronic phase affects body organs such as the heart, the digestive system and the nervous system. Close to two thirds of the patients with chronic symptoms experience a cardiac damage and this includes conditions such as cardiomyopathy which leads to abnormalities in heart rhythm and which is also very deadly. Approximately one third of the patients who exhibit the chronic symptoms experience damage in their digestive systems and this damage might result in the dilation of the digestive tract, accompanied by extreme loss of weight. The damage of the digestive system might lead to difficulties in swallowing food which is then followed by malnutrition. The Chagas disease may also lead to the development of secondary achalasia (Miles, 76-85).
Between twenty and fifty percent of the patients who incur intestinal problems also experience cardiac problems. Some of these individuals may also develop certain neurological disorders such as dementia. Chagas disease is clearly manifested when the cells of the target tissues begin to die during the infective cycle of this disease, and this sequentially induces cellular fibroids, lesions and inflammatory responses. If the patient fails to undergo treatment, this disease can become deadly because of the damage that it causes on the heart muscles (Miles, 90).
Plague is a very infectious disease that occurs in both human beings and animals. The global community of scholars has succeeded in tracing the routes of several global epidemics but the origins of infectious illnesses such as plague are still quite unclear. Plague is caused by a bacterium referred to as Yersinia pestis. People normally get this disease after being bitten by a rodent flea that carries the plague bacterium. It can also be contracted by individuals through handling a plague infected animal. This can either be through direct contact with the infected animal, through inhalation or even ingestion of infected materials, though this is a very rare occurrence. This means that the disease is highly contagious. During the middle ages in the history of mankind, many people died from this disease in the entire European continent when their homes and work places were occupied by flea-infected rats. Today, scientists have developed modern antibiotics that cure this disease. However, if an infected person fails to seek early treatment, he/she is likely to develop more illness or even die (Alexander, 123-132).
People who are infected with plague normally start experiencing symptoms which are closely related to the symptoms of flu and this normally occurs after an incubation period of between three to seven days. At this time, patients may generally experience impulsive fever, headaches, body aches, chills, nausea and vomiting. Manifestation of clinical plague may occur in three forms depending on the nature of the infection. These are bubonic plague, septicaematic plague and pneumonic plague. The most widespread and common type of plague is the bubonic plague which results from the bite of an infected flea. Septicaematic type of plague results from infections which are spread directly into the bloodstream. It may occur due to flea bites or from direct contact with materials that are infected. This may occur through cracks that form on the skin. The most dangerous form of plague is the pneumonic form and it is the least common type of plague. Basically, it occurs due to a secondary transmission of the bacterium from an advanced infection to the original bubonic form. The primary form of this type of plague occurs due to the inhalation of the bacterium droplets. It can be contracted from one person to another without the involvement of a vector such as animals or fleas. If left untreated, it may become very fatal (Alexander, 140-167).
Plague is widespread in most parts of Africa, in America, in Asia and in the former Soviet Union. In the year 2003, nine countries recorded two thousand one hundred and eighteen cases of plague and out of this; there were one hundred and eighty two people who died. Ninety eight point seven percent of the recorded cases and ninety eight point nine percent of the reported deaths occurred in Africa. Currently, the distribution of this disease correlates with its geographical distribution (Alexander, 170).
It is important for an individual to seek quick diagnosis and treatment of this disease once he/she becomes infected so as to decrease its chances of being complicated and fatal. Effective treatment of this disease involves the use of certain antibiotics and helpful therapy methods. If diagnosis and treatment is done in time, a patient is assured of absolute cure from this disease. Preventive measures that have been put in place to curb plague include informing people of the awareness of the specific areas where zoonotic plague is common, informing them to take precautions from flea bites and educating them on ways of handling carcass in plague-prone areas. In addition, people are advised to stay away from direct contact with infective tissues and patients who are infected with the pneumonic form of the disease. It is important to note that plague vaccines have been in use for quite a number of years but they have not been so effective in preventing this disease. Furthermore, vaccination is only suggested as a prophylactic measure for individuals who are at a very high risk of contacting the bacterium such as laboratory personnel, and not for instant protection in outbreak conditions (Alexander, 186-200).
Comparison of the four diseases
It is quite clear that the aforementioned four diseases share some common similarities in terms of their history, prevalence, symptoms and nature of occurrence, transmission and economic impact.
Nevertheless, there are also several differences that exist between the four diseases in terms of their symptoms, modes of transmission, their medication and their economic impact.
First and foremost, it is important to note that the historical roots of all these four diseases are still quite unclear. Even though researchers and scholars have succeeded in tracing the routes of many global epidemics, the origins of these four diseases can only be explained by use of formulated theories which are not quite sufficient. Another similarity that exists between these four diseases is with regard to their symptoms. It is rather clear from the aforementioned discussion that at the initial stages of all these diseases, the patient seems to experience some common fever.
These diseases are also share a similarity in terms of the existing forms of their occurrence. Both of them exist in different forms which are either acute or chronic. For instance, malaria may come in several forms with the chronic one being the cerebral malaria which affects the brain. Leishmaniasis comes in four main forms which are visceral Leishmaniasis, cutaneous Leishmaniasis, mucocutaneous Leishmaniasis and diffuse cutaneous Leishmaniasis. Chagas disease occurs in two stages, i.e. the acute stage which comes earlier and then the chronic stage which may occur after several years of infection. On the other hand, manifestation of clinical plague may occur in three forms depending on the nature of the infection. These are bubonic plague, septicaematic plague and pneumonic plague.
Another similarity that can be seen in these four diseases is in their nature of transmission. All the four diseases can be transmitted through a vector which is usually an insect. For malaria the vector insect is usually the anopheles mosquito. For Leishmaniasis, the vector insect is a sand fly of the species called phlebotomine. For Chagas disease, the vector insect is usually an insect such as the great black bug while the vector insect that carries the parasite which causes plague is the rodent flea. Nevertheless, Malaria can not be transmitted from one person to another while the rest of the three diseases are contagious and therefore can be transmitted from one individual to the other. Another major similarity between these diseases is that all of them cause adverse economic effects but key among them is Malaria. Lastly, it is also worth to note that even though drugs have been discovered to treat these diseases, most of these drugs have proved to be resistant and toxic to human body. In addition, even with the availability of these drugs, these diseases continue to cause many deaths especially in sub-Saharan Africa and other poor countries.
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To my mind, Malaria is the most serious and more devastating disease among the four diseases. This is because it is the major parasitic ailment in the entire universe. It is mainly prevalent in the poor communities of the world and it is commonly referred to as a neglected disease of the poor. It is basically one of the major challenges that face most of the poorest countries in the world. In the close of the year 2004, one hundred and seven countries and regions of the world had a very high risk of Malaria transmission and forty percent of the world's population was residing in these regions. It is approximated that five hundred million people contract Malaria every year and among them, two million die. Fifty seven percent of those who die come from Africa, thirty percent from Asian countries and around five percent come from America. It is a common saying that societies in which Malaria prosper most produces people who prosper the least. Worldwide distribution of per capita income and gross domestic product (GDP) indicate a very strong correlation between Malaria and Poverty (Kuby, 153-154). As such, the countries which record the highest prevalence of Malaria experience very little economic growth rates. Malaria can impede the development of a given country through affecting its fertility rates, saving and investment, population growth, medical costs, through causing premature deaths, decreasing employee productivity and increasing absenteeism among many other things.