Insects and Civilization: Vector-Borne Diseases

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Table of Contents

Definition
Malaria
Filariasis
Yellow fever
West Nile
Conclusion
References

Definition

A disease is an abnormal condition of an organ in the body brought about by an infection caused by a virus, bacteria, protozoa, or physical injuries that impair the correct body functions and that can be detected by specific symptoms and signs shown by the body. In a broader sense with regards to human beings, the disease is any condition that can cause excessive pain, distress, dysfunction, and even social problems. Diseases can be categorized depending on their causes. Such a classification can include diseases transmitted through air, water-borne diseases, sexually transmitted diseases, and vector-borne diseases. The latter groups consist of diseases transmitted from a vector as a result of a pest or insect bite that may contain the virus or the bacteria that cause the infection. Such diseases transmitted through a vector include malaria, filariasis, yellow fever, and West Nile.

Malaria

Malaria is a parasitic disease caused by protozoan parasites called plasmodium. Plasmodium is transmitted from the host, an infected female anopheles mosquito, through a bite to the victim. The parasites, once inside a human body bloodstream multiply in the liver and then infect the red blood cells. This hampers with blood supply to important organs and as a result, symptoms start showing up that includes: anemia, fever, chills, nausea, shortness of breath, and in severe cases coma and eventually death. Malaria is an epidemic disease worldwide but an endemic disease in Africa (WHO, 2007). Nearly 40% of the whole world’s population is exposed to the risk of contracting malaria. The threat is a reality in sub-Saharan African where statistics indicate that 60 % of all hospital admissions are malaria-related cases and worse still the disease kills one child out of twenty before they reach the age of five. Worldwide wide a child dies every 30 seconds as a result of malaria (WHO, 2007). Malaria is not merely a disease associated with poverty but it is also a cause of the same. This becomes a hindrance to economic development due to the large number of funds used to treat malaria that could have been used in other developing activities in poor countries. In some sub-Saharan African countries, the disease can account for up to 40% of public health expenditure. Apart from the cost of health care, other economic effects include man-hours lost due to sickness, time lost in education, and also lower productivity arising from brain damage caused by cerebral malaria. Time and money were lost in burials and loss of manpower in case of death. People at high risk of contracting the disease are pregnant mothers, small children, refugees, and travelers to sub-Saharan Africa. The geographic distribution of malaria is largely dependent on the climate of a specific region. Malaria is more common in rural areas than in cities, on the other hand, it is more prevalent in regions with hot, warm, and wet climates than regions with cool dry climates. Mosquito thrives well in warm wet conditions as they provide suitable breeding conditions. In drier areas, malaria outbreaks can be forecasted reasonably by mapping rainfall durations.

Filariasis

Filariasis also called Lymphatic filariasis is a parasitic and infectious disease caused by Wuchereria bancrofti, Brugia malayi and Brugia timori thread-like parasitic filaria worms called nematode worms. The parasites are transmitted from the vector to the humans through an infected mosquito bite. Once inside the bloodstream, the bacteria–containing worms find their way inside the lymphatic vessels where they mature and lodge into the lymphatic system and block the flow of the lymph. As a result of the obstruction the organ infected is distended, usually a limb, head, areas of the trunk, or even the sexual organs a condition known as elephantiasis or lymphodema. This enlargement is mainly the principal symptom of filariasis usually at later stages. Other symptoms may include a general feeling of ill health, a thickened skin pebbly in appearance, and ulceration. Over 120 million people have already been affected by it of which 40 million have been disfigured worldwide. A third of the infected people live in India, one-third in Africa, and the other third in south Asia the Pacific, and the Americas (BBC health news, 2008). The disease is, therefore, more severe in Asia than elsewhere. Individuals with the problem have to contend with social as well as physical problems. The main problem associated with this disease is stigmatization. People who have been disfigured by the disease are shunned by their communities and taken as outcasts. It has become hard for women with symptoms of filariasis to find a spouse and if married their spouses and families reject them. As for men genital damage is a severe handicap. Another social-economic effect is their inability to work well due to that disability and hence low productivity. Fight against filariasis like malaria, will be fighting against poverty.

Yellow fever

Yellow fever earlier called the American plague is an acute viral disease found in the tropical regions of Africa as well as the Americas and can be traced back almost 400years ago. It is transmitted via a bite of an Aedes or Haemogogus mosquito. The disease has two phases, the acute phase, and the toxic phase. The symptoms include fevers muscle pains headache, vomiting loss of appeti6te, and nausea afterward the patient develops jaundice where the skin becomes yellow, abdominal pains bleeding from the nose, mouth, and eyes and kidney fails. At this point, the patient may die within 10-14 days. The number of reported cases of yellow fever has been on the rise globally and now yellow fever is slowly becoming a public health problem. This has been traced down to the lapse of the yellow fever immunization programs in many countries, increased penetration of people into forested areas, and urbanization (WHO, 2007).

West Nile

According to the BBC health news (2008), West Nile Virus (WNV) is a virus found in both the tropical and temperate regions that mainly affects birds but is also known to affect humans, horses, cats, squirrels, and domestic rabbits. The virus is transmitted by culex mosquito vectors that bite and infect birds which act as amplifying hosts. The disease has no symptoms but sometimes the patient complains of mild flu-like illness, headaches, and muscle aches. The disease has been observed in Africa, Europe, Middle East, the Americas, Asia, and Oceania. As opposed to the WNV geographical widespread, the disease is not a serious condition in the world. Infections only occur in form of temporary outbreaks which then disappear.

Conclusion

Evidently, malaria is the most important of these diseases when we consider the socio-economic impacts and the geographical distribution. Malaria is ought to be a global concern and scientists should not tire their quest for either a cure of the above diseases or better still a way of wiping away the mosquitoes. Second in importance is filariasis due to stigmatization that is related to it. Others are important to a lesser extent since they are not very common in society today. An important observation in regards to the above diseases is their common mode of transmission, their lack of cure, and their areas of occurrence. If therefore the mosquitoes are eliminated then we shall have eliminated four diseases with them but as long as this remains a mirage man has to embrace the prevention methods.

References

World Health Organization. (2007): global surveillance of epidemic prone infectious diseases New York. Vol. pp 11-24.

British Broadcasting Corporations. (2008): Health news. BBC press. London.

Desowitz, R.S (2006):The malaria capers. More tales of parasites and people, research and reality. W.W. Norton & company publishers. Washington D.C.

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