Most Contagious Animal Diseases example essay topic

John Lyles Dr. Sicke l Zoology 25 April 2002 Foot and Mouth Disease Throughout my life I have been fascinated with feet. This fascination is the result of having many foot problems as a child and as a young adult. When thinking of a topic that has to do with both Zoology and the human foot, one thing came to my mind, and that is Foot and Mouth Disease. Although not prominent here in America, this disease has caused much panic in Europe and in the far Western countries. This disease is something that should not be taken lightly and ignored, its effects can cause much damage to our economy and financial lives.

The United States should not ignore this disease and people should have a general knowledge of it so that we can prevent an outbreak here. Foot and Mouth Disease (FMD) is one of the most contagious and most feared of infections. It is one of the most contagious animal diseases known with an infection rate near 100%. Once a strand is started and begins infecting animals, an epidemic of enormous proportions is likely to follow. It is mainly found in cattle and swine. However, it is also very dangerous to other hoofed animals including deer, goats, and sheep (USDA, 2001).

Learning about the disease and how it moves is the only way to try and control it. The three basic areas foot and mouth disease are the disease characteristics, the disease movement, and finally methods of controlling it. The clinical signs for both swine and cattle are both very similar to one another. In swine, after the incubation period is over, pigs (swine) will also show certain signs before the clinical effects set in on them. They will pyrexia (fever), anorexia, and lethargy.

The animals infected with FMD will not want to walk at all and seem to be extremely lame. Once the disease begins its clinical stage, lesions begin to form on the body, and just as cattle, vesicles begin to form on the snout, mouth, and coronary band. These vesicles and lesions often lead to secondary infection. These will usually be very harmful to the animal (Foot and Mouth Disease, 2001).

In cows, there are is a 2 to 14 day incubation period where the cow is infected but the effects are not noticeable, so a farmer, unaware of the problem, actually spreads the virus without any clue of a threat of FMD. The only warning given before the clinical (visual or health) effects are noticed is a dramatic drop in milk in dairy cows. This drop is followed by the serious clinical signs of pyrexia up to 41 degrees Celsius, salivation, nasal discharge, vesicles on the mouth, feet and udders, acute lameness, and "Chomping" of the jaw caused by pain in the mouth (Foot and Mouth Disease, 2001). The disease itself is not lethal to the animal; it merely attacks its body and may in a round-a-bout way lead to its death.

In cattle, for example, many times FMD leaves the cow with chronic lameness, a permanent drop in milk, inability to effectively gain weight, and a decrease in the quality of its coat (USDA, 2001). The effects of FMD are far more horrifying to the farmer and to his family, than to the animal itself. Death, however, does occur very frequently in young animals which contract the disease. Myocarditis, defined as inflammation of the heart chamber, (American Heritage, 1992), is the major killer of infected young animals (Foot and Mouth Disease, 2001). In cattle and swine is where the worst clinical effects of FMD occur. Similar effects are present in sheep and goats, but they are milder in comparison.

Sudden lameness may be seen in the entire herd once the disease has set. Vesicular lesions (like those of cattle and swine) are found in the coronary band, the inter digital space, and on the bulbs of the feet. Sheep vesicles are often smaller and much harder to find. Close examination and particular care to each cleat of a sheep must be taken in prevention and detection of FMD (Foot and Mouth Disease, 2001). Infection can occur by many different ways. They include inhalation, ingestion, and through damaged epithelium (Foot and Mouth Disease, 2001).

Contact with an animal infected with FMD can also lead to infection. The excretion made by infected animals is the biggest problem when trying to control FMD. The disease is excreted through all secretions and excretions of the animal (USDA, 2001). The disease lives in animal saliva, nasal discharges, any vesicles, milk, semen, wastes, and shed skin. With all of these possibilities of contraction, it makes it seem impossible for an animal not to pass the disease to others. Contact with infected animals by uninfected animals is obviously the most popular and most frequent of transmitting the disease from one individual to the next.

A problem with trying to prevent this lies in two factors. FMD has an incubation period of 2-14 days during which the signs of the disease will not be noticeable even though the animal is indeed contaminated and able to transfer the disease. The other factor in trying to prevent interaction with contaminated animals is that many animals are simply carrier animals. Many times swine are the carrier animal in a strand of FMD. These carrier animals may only have very slight indications that are very hard to notice (Foot and Moth Disease, 2001).

Since FMD can be of great epidemic proportions tracking the progress of infection is very important. The most effective way of tracing FMD is by looking for he lesions and vesicles produced on the cows and swine. "Ageing of Lesions" is a process that allows scientists and biologists to figure out when that particular animal contracted the disease. A change in size color, intensity, and deposition of fibrin are the different characteristics studied in this process. Scientists and biologist call the cow with the oldest lesion the "index cow". That particular cow's infection date is found by adding approximately 2-14 days, allowing for the incubation period, onto it.

The time this cow was infected is estimated to be the time when that particular strand entered the farm (Foot and Mouth Disease, 2001). The epidemiology is another important aspect of Foot and Mouth Disease. Epidemiology, the study of the spread of the diseases, is a very important idea to FMD (American Heritage, 1992). Foot and Mouth Disease is considered the most contagious animal diseases known (USDA, 2001). The small amount needed to infected and the large amount excreted by infected individuals, plus the variety of routes that the disease is passed on make it very dangerous to all susceptible animals (Foot and Mouth Disease, 2001).

Although FMD is classified as a zoonosis, a disease transferable to humans, there is no major concern for their well being. Only a few cases have been found dealing with humans. Symptoms include small blisters on the hands, slight fever and sore throat. These occurrences are very unlikely and do not happen very often at all (Prempeh, 2001). A press release by the OIE, warned of the threat that Foot and Mouth Disease can cause. "FMD is highly contagious and can spread rapidly in livestock through movement of infected animals and animal products, contaminated objects and even wind currents".

Dr. Di ouf, in an article from the UN, is quoted as saying, "For animal diseases, we need a system similar to the one already in place for food crops: A Global Information and Early Warning System for transboundary animal diseases which takes account of the official reporting of the Office International des Epizooties, disease investigations, epidemiological and laboratory studies in the countries to improve international early warning" (Caribbean News Agency, 2001). The best idea scientists can come up with for controlling FMD is creating a system to warn other nations and areas of the discovery of FMD within its borders. This system would serve as a major step towards the complete containment of the disease. Many people believe that only through direct contact can diseases and viruses be contracted. This is definitely not true in the cases of foot and mouth disease. There are many ways that an animal can be contaminated.

Another method of contamination is with products used in handling contaminated animals. All body products created after infection are more than likely carrying the disease and are very much able to infect other individuals (Foot and Mouth Disease, 2001). For instance, let's say a cow contracts FMD and then produces wastes that falls to the ground. Undoubtedly, waste produced within a few hours of contamination will be carrying the disease.

So, any other farm animal that simply walks over that waste with some type of entrance to their body (lesion, cut, pore) is susceptible to contamination themselves. Also, anytime an infected animal nurses their young, their offspring is then infected. These products produced by infected animals are things very hard to control in the effort to control FMD (Foot and Mouth Disease, 2001). Contact with contaminated personnel and equipment is also a major concern when trying to control FMD. Although the disease does not affect humans directly, it can be transferred by farmers and humans who contact clean livestock. The ability of the virus to survive on infected equipment depends on the conditions surrounding the equipment and whether the virus is able to survive under those conditions (Foot and Mouth Disease).

All three of these previous methods are potential means of contamination. However, the method that affects the most individuals is the wind borne transportation of the virus. Although it is not the most frequent, it affects more animals than any other method. Pigs are the main source for airborne virus. On average, pigs excrete 3000 times more of the virus into the air than cattle or sheep. Other sources of the airborne viruses include slurry, burning of infected carcasses, and the air venting from milk tankers.

If certain conditions are available, such as humid, cool conditions with a low wind speed in constant direction, the airborne FMD virus can travel miles and mile to infect other communities of animals (Foot and Mouth Disease, 2001). FMD raises other concerns besides medical problems. This all-encompassing disease many times destroys the yield of a herd of cattle, limits the milk production and usually prevents growth for the rest of the animal's life. A farmer whose income and economic balance relies on his cattle and milk sales can be ruined by an outbreak of FMD (Prempeh, 2001). Many efforts are being made to control and try and prevent more epidemics from rising. Trade barriers, trade regulations, and new safety and cleansing products are being administered to handlers of livestock.

The Office International des Epizooties released a statement predicting the eradication of FMD by the year 2009 (OIE, 1996). This eradication of foot and mouth disease would mean the end of one of the most economically and physically devastating disease known to man, or animal. With the knowledge of how the disease spreads and its effects upon humans and livestock, the world needs to unite together to stop the spread of FMD. This disease not only causes much panic economically speaking for countries infected by the disease, it can cause a great panic for the citizens and people living within the borders of it. Even though to many people the foot is just something we use to walk with, to me, feet are essential for maintaining comfort and fitness for humans.