The Impact of Insects on Human Life, Term Paper Example

Introduction

Insects are an inevitable part of the human life in the world. Some have positive effect on human life, others have negative impacts in that they tend to cause harm to people. There are those which have no impact at all to human life. This paper is dedicated to those that impact negatively hence resulting in harm, discomfort and disease. Three diseases, Malaria, West Nile Virus disease and Chagas disease have been handled in detail.

Malaria

Causes

This disease is caused by microorganism belonging to the genus referred to known as plasmodium which contains five species namely: Plasmodium malarie, Plasmodium ovale, Plasmodim falciparum, Plasmodium vivax and Plasmodium knowlesi. This disease may result in a coma or even death. The disease caused by Plasmodium falciparum is more fatal and is responsible for the highest number of deaths attributed to malaria as compared to the other four species. Plasmodium vivax is on the other hand responsible for the highest malarial infections in most parts of the world. When a person has been infected, the parasites which are now referred to as sporozoites are absorbed into the blood stream in which they travel to the liver. Once in the liver, they mature for some time and change into a new form and are called mesozoites which enters and infect the red blood cells. The symptoms of the disease are experienced when the parasites start multiplying inside the red blood cells (Sturm, 2006, 1284). The disease is wide spread in tropical and subtropical regions of the world and these include Latin America, Sub-Saharan Africa and Asia.

Infection

Infection is achieved when one is bitten by anopheles mosquito hosting any of these plasmodium parasites. This therefore means that the parasites may be transferred from one person to the other by a mosquito bite provided the first person bitten has the organisms in his or her blood stream. When a mosquito bites an infected person, it ingests the plasmodium parasites which then fuse further inside the mosquito’s mouth and produce an embryo-like structure called ookinete. The ookinete then penetrates the lining of the gut to produce an oocyst which later on ruptures to release the parasites now called sporozoites (Sturm, 2006, 1288). These parasites then migrate back into the salivary glands of the mosquito through its body. Once in the glands, the parasites are ready to enter and infect a new host whether it is an animal or a human. When a mosquito carrying the sporozoites bites to have its blood meal, it injects the sporozoites into the skin thereby causing an infection and this is known as anterior station transfer. It is worth noting that it is only the female species of the anopheles mosquito that is responsible for malarial infection (Mandell, 2009, 193).

Another possible way of transmitting malaria is when a pregnant mother transmits it to her unborn baby. This is called congenital transmission and is responsible for the majority of deaths in unborn babies. Infection can also be through blood transfusion especially if the blood being transfused has been infected by the plasmodium parasites (Mandell, 2009, 194).

Signs and symptoms

As stated here above the major signs and symptoms are seen or experienced once the parasites have entered the red blood cells. As the multiplication of the parasites inside the red blood cells continues, individual red blood cells affected burst open. The bursting of cells releases the parasites which then infect the adjacent cells. This infection and bursting of an individual cell is a process that takes place within a period of about 42 to 72 hours.

Once a person has been infected it may take between 7 days to 5 weeks for the symptoms to start being experienced. The variation is dependent on the amount of parasites that initially entered the person involved and also the rate at which the parasites are multiplying inside the person’s red blood cells. In some rare cases it could take up to a year for the symptoms to start appearing.

The symptoms of the disease include:

• Anaemia which is usually as a result of the bursting of the red blood cells,
• Fever,
• Vomiting,
• Sweating,
• Convulsions in children and
• Bloody stool.

Prevention

The surest way to prevent malaria as a disease is by preventing mosquito bites, especially by the anopheles mosquito. This therefore means all measures directed at preventing mosquito bites will definitely result in reduced cases of malarial infections.

Preventive measures include:

• Use of mosquito nets treated with insect repellants in homes
• Spraying insecticides
• Draining stagnant water which would otherwise form the breeding homes for mosquitoes.
• Use of preventive vaccines.

Treatment/Medication

This is done by the use of drugs that contain derivatives of quinine and/or artemisinin. This could be in the form of ingestion tablets on injection doses. The malaria parasites have in the past developed resistance to certain anti-malarial drugs and this has prompted a continuous research to enhance the production of the most effective drug to fight malaria.

Dosage as recommended by the physicians should be adhered to because misuse or abuse of malarial drugs has been the greatest factor contributing to the resistance of the parasites towards the drugs. People who want or intend to visit areas prone to malaria disease temporarily should be given some preventive medication by use of drugs such as mefloquine, atovaquone and doxycycline. Preventive drugs should only be taken by visitors who are temporal in these areas but not the original inhabitants of these areas because the drugs have side effects when used for a long time.

West Nile Virus Disease

Also referred to as West Nile encephalitis, this disease is caused by both bacterial and viral infections. The disease is caused by a virus that was first discovered in 1937 in Uganda on the western side of River Nile. This is what prompted its naming as the West Nile virus (Smithburn, 1940, 472). To date the virus has been found, commonly, in Africa, the Middle East, Eastern Europe and west Asia. The virus has been detected in birds, humans and some vertebrate animals (Taylor, 1953, 210).

Causes and infection

The disease is caused mainly by bites from mosquitoes hosting the virus as a result of feeding on either alive or dead infected birds. There are possibilities that it could also be transmitted through processes such as organ transplant, blood transfusion and from a pregnant mother to the unborn baby, however these cases are very rare (Taylor, 1953, 213).

Different people are at different risks of getting infected by the disease, for example, being outdoors while working or playing exposes one to mosquito bites that would in turn infect him or her with the West Nile Virus. Also, people aged 50 years and above are at a higher risk of developing severe illness if at all they get bitten by infected mosquitoes (Mandell, 2009, 222)

Signs and Symptoms of infection

Infected people generally develop symptoms after 3 to 14 days. The symptoms of the people infected may be grouped in three main groups as:

• Serious symptoms

Some of the people infected may experience severe conditions such as headache, high fever. Neck stiffness, convulsions, muscle weakness, coma, paralysis, numbness, disorientation, stupor and vision loss which may last for several weeks. The neurological effect as a result of this may be permanent. This represents about 0.7 % of all the infection cases reported.

• Milder symptoms

About 20% of the people infected may report milder symptoms such as vomiting, fever, headache, body aches, swollen lymph glands and skin rashes on the stomach, back and chest. Symptoms may last for a few days.

• No symptoms

A majority of people infected by the West Nile Virus do not show any symptoms as a result of the infection. The percentage is as high as 79% (Mandell, 2009, 213).

Prevention

This disease can be prevented by embracing measures that aim at reducing mosquito bites especially from the Culien Pipiens mosquito. These measures include:

• Wearing long clothes that cover legs and hands to prevent mosquito bites
• Draining and getting rid of stagnant water for this easily becomes breeding grounds for mosquitoes if left unattended. This includes water in buckets, flower pots, barrels and children’s swimming pools
• Use of mosquito nets effectively treated by mosquito repellants in homes. This could be used in windows or doors and also in the bedroom’
• Spraying of insecticides in areas believed to have the Culien Pipiens The insecticides used should contain components registered by EPA.
• Any dead birds should be reported to the relevant authorities before it can be discarded. In addition such birds should not be handled with bare hands.

There is no known preventive vaccine for humans against the disease.

Treatment/Medication

So far there is no known and specific treatment of west Nile virus disease. The infected people who show milder symptoms get well with time. Fr those who show serious symptoms, it is advisable that they visit hospitals so as to receive a more supportive treatment which includes help in breathing, supply of intravenous fluids and general nursing care (Mandell, 2009, 215).

Chagas disease

This is a disease also spread by insects and is common in both Central and South America. It is believed to have originated from the African continent and was probably carried to South American continent by immigrants.

Causes

The disease is caused by a Trypanosoma cruzi parasite and is carried about by reduvid bugs. The risk factors involved are: living in huts with cracked holes in which the bugs hide in the cracks and also undergoing transfusion process in which the donor has the parasite in the bloodstream but does not show active symptoms of the disease (Mandell, 2009, 233).

Signs and symptoms

The disease profile has two phases namely; the acute phase and the chronic phase.

The acute phase is characterized by very mild symptoms and even in some cases no symptoms at all. In case of the mild symptoms in the acute phase, they may include:

• Swollen area around the point at which the insect bit and is usually red in color.
• Swelling of either the left or the right eye.
• Fever
• Malaise

After this phase, the symptoms disappear completely and the person may appear totally healed when actually he/she is not. At this point the disease is said to have gone into remission. Once in this stage none of the symptoms may appear for a long time. This normal-like situation may go on for many years. Finally the chronic phase comes and the symptoms develop. These symptoms include:

• Problems with the digestive system
• Abdominal pains
• Difficulties in swallowing solid foods
• Recurrent constipation.

An examination by a physician to ascertain the disease can be carried out and in case of an infection the following will be noticed;

• Liver and spleen abnormally enlarged.

• Heartbeat occurring in an irregular or rapid manner.
• Lymph nodes abnormally enlarged.

Prevention

Successful prevention measures are those that target at having an environment with less infectious insects. This can be achieved by the use of insecticides. These insecticides are sprayed in and around homes to kill any reduvid bugs which carry the parasite causing the disease. People should also, by their own effort, strive to stay in a healthy environment which includes homes free from infectious insects.

Other preventive measures include the screening of blood before a transfusion exercise is done to ascertain whether or not it is safe for use. This is being done in most blood banks in South and Central America. If a particular donor tastes positive, the blood should be discarded immediately (Mandell, 2009, 238).

Treatment

The relevant and necessary treatment should be provided for both of the acute and reactivated phases of the disease to avoid any further health complications. In addition, the infants who are born with the disease should be given the right treatment.

As for the chronic phase, it is recommended that treatment should be provided for, in both the children and the adults. The adults should also talk to their doctors about the most effective treatment of the disease.

Treatment is usually achieved by the use of two major drugs namely: nifurtimox and benznidazole. It is however important to note that these drugs when used have pronounced side effects on the patients. Some of these side effects are:

• Dizziness accompanied by headaches
• Loss of weight
• Loss of appetite
• Having problems when it comes to sleeping
• Development of itchy skin rashes on the skin.

It has been found that about one third of the infected people who end up not being treated may at one point in life develop chronic phase of the Chagas disease. Other problems such as heart related problems and digestive problems may take more than 15 years since infection time to start being experienced.

Conclusion

As seen above, some insects have harmful effects on human life. The harm is usually as a result of the insects going about their survival activities. This therefore calls for measures to ensure smooth existence of both humans and insects because after all both have to, somehow, occupy some space on this planet.

Works Cited

Mandell, Bennett. et al. Principles and Practice of Infectious Diseases. Philadelphia, PA: Elsevier         Churchill Livingstone. 2009.

Taylor, Hurlbut. et al. Isolation of West Nile virus from Culex mosquitoes. Cairo: Egypt Medical Association. pp. 199-208. 1953.

Smithburn, Paul. et al. “A Neurotropic Virus Isolated from the Blood of a Native of Uganda”. American Journal of Tropical Medicine. Vol. 20.1: pp. 471-492. 1940.

Sturm, Heussler. et al. “Manipulation of host hepatocytes by the malaria parasite for delivery into liver sinusoids”. Science Vol. 313.5791: pp. 1257-1290. 2006.