Filariasis, Malaria, Dengue Fever And Lyme Disease

Insects-the most diverse group of animals on Earth, are the major group from arthropods class. Insects could be found in almost everywhere, in any conditions, and environments, which why we would classify insects as the most successful, and diverse organisms to dominate the earth’s population. However, these magnificent, simple yet sophisticated organisms are capable to produce massive casualties. The manner of how these diseases are introduced to human through insects will further be discussed in this paper. This paper will attempt a further analysis on the history, the distribution of the diseases worldwide, and the further impact noted caused by the diseases.

Vector could be defined as an organism that does not involve in causing disease itself, but responsible in conveying pathogens from each host to another which in this case; the insects. These diseases can be transmitted to human through various ways, and one of them: mosquito bites. Therefore, in this paper, I will further discuss on four major vector-borne diseases; Filariasis, Malaria, Dengue fever, and Lyme disease.

I will begin my discussion on Filariasis. Filariasis which also known as Lymphatic Filariasis, is spread from an infected human (the carrier of the disease), to other healthy human by mosquitoes. This disease caused by a type of parasitic adult worms called microfilaria (Wuchereria bancrofti, Brugia malayi) that lives and reproduce in human’s lymphatic vessels. The female worms will release large numbers of very small worm larvae, which circulate and infected human’s bloodstream. Thus, when a human is bitten by a mosquito, the mosquito would ingest the larvae, and it would continue developing in the mosquito into an infective stage, which later will be transmitted to other human via same methods; mosquito bites. And again, once a human is bitten, the larvae will passed through the human skin and travel all the way to the lymphatic vessels and it will develop its new cycle to grow into adult worms.

This disease is discovered in 1866, when Otto Wucherer demonstrated the presence of microfilaria, which consists of filarial larvae in urine, followed by Timothy Lewis in 1871. He discovered the presence of microfilaria in peripheral blood. Another discovery made by Joseph Bancroft in 1876, which he claim to discovered the adult form of the worms in the lymphatic vessels. And in 1878, Patrick Manson claim to observe the development of Wuchereria bancrofti in the mosquito. One of the key worms that responsible to initiate filariasis is named after these two prominent discoverers, Wucherer and Bancroft.

Filariasis is extremely rare in Western world, but it is an endemic in tropical regions of Asia, Africa, and South America with over 120 million of people has been infected with it. The primary cause the disease to took place is more likely due to rapid growth of developing nation, which creates numerous breeding sites for mosquitoes, and other vectors and permit �them’ to transmit the disease. Over one-third of people who are diagnosed with disease, are living in India, which represents the largest pie of the disease distribution. Another one-third of the pie are in Africa, and the rest are in South Asia, especially South East Asia, Pacific, and South America. The Brugia malayi and the Brugia timori has affected more than 12 million people in South East Asia. As we could see, the species name Malayi and Timori indicates Malaysia and Indonesia as the most dominant breeding sites for these species.

Those who carry the disease would most likely displaying viable horrendous symptoms; such enlargement of the entire leg or arm, and in some cases it would affect the genital parts; which would also be referred as Elephantiasis, due to thickening of skin and underlying tissues. Notable symptoms could be observed between 5-18 months after mosquito bites. Tissue damage caused by the worms will restrict the normal flow of lymph fluids which may results in swelling, scarring, infections, and it is believed that filariasis most likely would cause permanent disability.

Filariasis has no clear vaccine. Thus, the best way to eradicate the disease is by eliminating microfilaria from the infected individuals, which therefore will interrupt the process of transmitting the infection by the mosquito. Administration of diethylcarbamazine concurrently with albendazole or invermectin (DEC) is proven to eliminate 99% of microfilaria from the infected individual. Albeit advance treatment of this disease is currently available, vigorous action should be taken by the communities and the respective agencies to abolish all potential breeding sites for mosquitoes.

WHO classify this disease a disease of the poor, due to its pervasiveness to occur in remote rural areas. Thus, if I were to construct two premises on filariasis, I would say; first, to have a filariasis is to live in poverty. Second, people are infected by filariasis. And therefore, I would conclude that those who are infected by filariasis are most likely to live in poverty. As has been stated by the WHO, “the fight to eliminate filariasis is also a fight against poverty”.

Malaria is another example of vector-borne infectious disease that uses mosquitos as vectors and would infects the blood. Malaria remains a big problem in many sub tropical and tropical countries. The United States is considered Malaria free since it has been eradicated in this country since early 1950’s. However, over 1300 cases of malaria, including 8 deaths were reported in 2002. Estimated 41% of the world’s populations live in areas where malaria is transmitted. Malaria is deemed as a leading cause of death and disease worldwide, mostly reported in developing nation especially South East Asia, and Africa. Malaria is so common in Africa the principal malaria mosquito; Anopheles gambiae is malaria prone, and fond to transmit malaria efficiently.

The parasite is transmitted through the bite of a mosquito and it travel to the liver to reproduce. The protozoan parasite which is most harmful is Plasmodium falciparum, and Plasmodium vivax as it contributes to the highest deaths and infections. When a mosquito bites, a trace amount of blood is taken which contains malaria parasites. The parasite will continue to develop and grow in mosquito’s gut for about a week, which later will be transported to mosquito’s salivary gland. Thus, whenever mosquito consumed blood from other healthy human, they would transmit the parasites into the new host. The parasites will travel to the liver to grow and multiply, this is called the �incubation