Beyond the acute phase: a comprehensive literature review of long-term sequelae resulting from infectious diseases

Montana Argues In Lawsuit That Yellowstone Bison Are A "more Significant Risk" Than Elk

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Brucellosis: Disease You Get From Infected Milk

Dear Daktari, Thank you for your informative articles. I have a query. I started feeling fevers, which would come and go. I first suspected malaria but after it persisted even after I had finished my dose, I went to the hospital and was diagnosed with brucellosis. My doctor told me it is mostly gotten from cow milk. A month early my cow had aborted and its milk production greatly reduced thereafter. After reading online on this disease, it occurred to me I could have picked the disease from my cow. Please educate us on this disease. [Nicholas Wafula, Bungoma County]

Thank you Wafula for volunteering to share your experience. Brucellosis is a zoonotic disease, which most people confuse with malaria. It is not good to self-medicate. Whenever you are sick always, visit your doctor for treatment. This will also help us prevent the problem of Antimicrobial resistance.

Brucellosis is a bacterial disease that affects cattle and causes great economic losses. Abortion is the commonest clinical sign in cows. The disease spreads very fast within a herd. A cow that is infected and not treated may carry the disease. In human beings, the disease presents with fever. Brucellosis is spread through consumption of infected milk - drinking raw or unpasteurised milk and consumption of raw or contaminated dairy products, eating of undercooked meat and meat products from infected animals and contact with infected aborted feotuses.

How is the disease spread?

An infected animal will spread brucellosis causing bacteria through milk and this can happen for a long period. Transmission occurs through ingestion of brucellosis causing bacteria, which is present in aborted feotuses, feotal membranes and vaginal discharges from an affected animal. These organisms contaminate water, animal feeds from where they are ingested. Infected bulls will spread the disease during mating. However, artificial insemination can also spread the disease when the equipment used are contaminated. To confirm the diagnosis, lab tests should be done on milk, vaginal discharges and feotal membranes from an animal suspected to be suffering from brucellosis.

Treatment and prevention

In countries where this disease is eliminated, imported animals are quarantined and tested. They have to test negative before they can be mixed with the herd. Protecting the none infected herd is a prevention strategy employed in such countries. Vaccines against brucellosis are available. Quarantine and movement controls are used to contain spread of the disease in outbreaks. Sanitary measures like handling of infected materials using personal protective equipment can minimise the spread.

[Dr Othieno is a veterinary surgeon and the head of communications at the Food and Agriculture Organisation of the United Nations (FAO) Kenya. The views expressed here are not necessarily those of FAO]

Bison Outside Yellowstone National Park

Though bison are well-suited for the harsh climate of Yellowstone National Park, the winters from 1995 to 1997 were particularly severe in the high country, forcing bison to leave the park in search of food. They found milder conditions and convenient grazing on several U.S. Forest Service allotments that were used by area cattle ranching families in the summer.

In 1995, the Yellowstone bison herd was designated by the Montana state legislature as a species in need of disease management, as some bison carry brucellosis.

The Montana state legislature then designated the Deparment of Livestock (DOL) to be the lead agency for the bison/brucellosis disease management outside of Yellowstone. It was the DOL's responsibility to work with other state and federal agencies either to force the bison leaving Yellowstone National Park back within park boundaries or to capture and test for brucellosis those bison that could not be moved back into the park. The DOL's role in bison management has been problematic for environmental groups who believe that wildlife officials, not a livestock agency, should be managing bison.

Brucellosis

Ranchers are nervous about mingling between cattle and bison because of brucellosis, which can decrease milk production and animal weight, cause spontaneous abortion of the animal's first fetus and cause infertility. For nearly 60 years and at a cost of billions of dollars, the livestock industry across the United States has waged a war to eliminate brucellosis from its herds. In 1952, the U.S. Department of Agriculture (USDA) estimated that annual losses due to this disease were more than $400 million. To prevent an epidemic of the disease, federal and state agriculture officials have eliminated infected herds.

Brucellosis can also infect human beings, causing persistent, intermittent flu-like symptoms known as undulant fever. Transmission occurs through direct contact between a person's open cuts and birthing fluids or animal tissue. Veterinarians, butchers and farmers have been those most commonly affected, though the incidence of brucellosis in humans is extremely rare.

Brucellosis was first identified in domestic cattle in the United States in 1910. In 1917, it was first identified in Yellowstone bison.

The USDA, responding to livestock and public health concerns, began an effort to control and eradicate brucellosis in 1934 by developing vaccines and depopulating entire herds when several animals tested positive for the bacterium. Currently, all but Florida and South Dakota are brucellosis-free, and these last two states are poised to eradicate the disease.

After more than 30 years and $30 million, and the sacrifice of many cattle, Montana achieved brucellosis-free status in 1985. That same year, state and federal agencies began eliminating some Yellowstone bison that migrated out of park boundaries. Since the winter of 1991-92, Native Americans from reservations such as northern Cheyenne, Crow, and Fort Peck have sometimes assisted in harvesting and using the bison carcasses. Other bison carcasses have been distributed to nonprofit charitable organizations and food banks.

A scientific dispute

Yellowstone's bison herd carries an uncontrolled pocket of the disease. However, detractors of the slaughter believe there are flaws in the bison management:

Bison migrate out of the park to graze in the winter and spring, whereas cattle are not placed on the allotments until June, after most bison have gone back over the park border. However, there is disagreement about how long the Brucella bacteria can survive in the environment. As a precaution, cattle and bison are kept from interacting for at least 45 days.

Transmission occurs mainly through direct contact with birthing matter, but state and federal officials have included hundreds of male bison in their slaughter, contending that males still present a risk.

Methods of testing for brucellosis are hardly foolproof. Among those bison who field-tested positive for brucellosis and were killed between 1996 and 1999, 80 percent later tested negative for the disease in more reliable lab tests.

Thousands of elk in the region also carry the disease, but are not managed similarly.

There has been no documented case of brucellosis transmission in the wild between cattle and bison. Known transmission has only occurred in the lab.

Today, some tribes and Native groups are trying to reintroduce bison onto their reservations. They are also working to take in unwanted bison from Yellowstone instead of having these animals sent to slaughter. So far, these requests have been denied by government officials.

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