Dr. Mario Villarino Informs Us of

the Disease Wild Hogs Carry

 

Wild hogs: more than just a not welcomed visitor

During the last part of 2015 and early in January, I got involved in talks related to wild hogs. A recent facebook post showed a sounder (group of adult hogs) roaming during the day in Hopkins County. The rancher, recently moved from West Texas to Hopkins County was shocked after finding the hogs roaming his property. I talked to him about direct damage done by the wild hogs to his property but failed to mention the risk of disease transmission by the hogs. Wild hogs are more than unwanted visitors, they can also be a source and transmit diseases.

According to Donald Davis (Texas A&M University) feral swine like all animals wild or domestic are susceptible to a wide range of infectious and parasitic diseases. Some of these diseases are specifically limited to pigs (Sus scrofa) and while some of the other diseases are shared with other species of wildlife and domestic livestock and a few diseases of feral swine are also shared with humans. Although not an indigenous wild species in North America, populations of feral swine (domesticated pigs that have returned to the wild state) are of sufficient number, ecological impact, and distribution to consider them wildlife in many areas, particularly in the Southeastern United States.

Recent estimates of the number of feral swine in the United States vary from 1 to 3 million. The largest number of feral swine are believed to be in Texas, Florida, and California. Feral swine are commonly hated and loved by different segments of society in the same locations. As the numbers and geographic distribution of feral swine continues to increase, it is certain that the number of contacts between feral swine and domestic livestock will also increase as will the probability of human exposure to feral swine directly or indirectly. Not a great deal of information has been documented on the diseases of feral swine let alone any information of diseases spread from feral swine to livestock and humans. Brucellosis and pseudorabies are two diseases of feral swine that have been fairly well documented because of ongoing Federal Eradication Programs. Brucellosis is a bacterial infectious disease of animals and humans caused by members of the Genus Brucella.

The effects of the disease in the primary host caused by the various species of Brucella is generally limited to abortions and reproductive organ infections. In other host species such as humans, the disease clinically may mimic severe flu and may vary to crippling arthritis or meningitis. There is no cure for brucellosis in animals and humans are treated with very high doses of antibiotics for extended periods to hopefully clear the infection. The wide geographic distribution of feral swine and the fact that they are known to be capable of transmission of brucellosis to humans and domestic livestock should be of some serious concern to governmental agencies responsible from the control and/or eradication of this disease. Pseudorabies is an infectious, often very acute viral disease of the central nervous systems of feral swine that also is found in domestic livestock, cats, and dogs. Pseudorabies is not a zoonotic disease so humans are not infected. Pseudorabies is also known as Aujesky’s disease, mad-itch, and pseudohydrophobia.

 

 

The disease was first reported in naturally infected oxen, cats and dogs. Up to the early 1960’s in the United States, pseudorabies virus (PRV) was found in young domestic swine and caused limited amounts of mortality. After that date more virulent strains began to occur and losses among adult swine were observed. Now PRV commonly causes abortions and mortality in adult sows. The disease in swine may be spread by asymptomatic carriers, and in carnivores are readily infected by contact or ingestion of infected tissues or carcasses. The signs of pseudorabies vary widely from species to species, but anorexia, excessive salivation, spasms and convulsions are usually observed in all species. Mad itch is commonly seen in species other than swine, and pseudorabies is almost always fatal. Transmission of the PRV may occur through direct contact, aerosals, contaminated feed, water, ingestion of infected tissues, or contaminated footwear, clothing or trailers. Diagnosis is usually made on clinical signs and a variety of serological tests.

Prevention and control programs for PRV in domestic swine vary from test, isolation, removal, and slaughter methods that may or may not be combined with a vaccination program to increase herd immunity and prevent the shedding of the PRV. The only method to control PRV in feral swine to date is population control. PRV virus has been isolated from feral swine in Texas and Florida, and serologic evidence of PRV has been demonstrated in other areas. The spread of PRV from feral swine to domestic cattle has been observed on multiple occasions in Florida and Texas. Contamination by feral swine of supplemental feed spread on the ground for cattle is suspected as the source of infection.

This spread from feral swine to domestic swine and cattle is seen as a serious obstacle to the Federal Pseudorabies Eradication program. The exact infection rates of PRV in feral swine populations, the precise amount of transmission from feral swine to livestock, and the geographic distributions of PRV infected swine populations is not well known. Examples of other infectious diseases of swine that are now foreign to the United States but ones that could present a threat to the entire domestic swine industry if they should reach the continental United States are African swine fever, hog cholera, and foot and mouth disease. The last reintroduction of foot and mouth disease into the United States was in the 1920’s in California.

That resulted in the eradication of over 22,000 black-tailed deer in the Stanislaus National Forest. With more than 115,000 head of cattle in Hopkins County, and the potential implications of feral hogs as diseases carriers to both human and animal diseases, controlling feral hogs becomes more important than just because the damage cause directly by them.

Coming up programs:  Pesticide Private Applicator Licensing. February 17, 2016 8:00 to 12:00 $25.00 Lunch included. Register by calling 903-885-3443.

Programs of the Texas A&M AgriLife Extension Service are open to all people without regard to race, color, sex, region, national origin age, disability or veteran status.

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