Wildlife & Human Health

Some diseases, known as zoonotic diseases, can be transmitted from wildlife to humans. Fortunately, in Massachusetts many of the most prevalent zoonotic diseases are easily preventable, identifiable, and treatable. Click below to learn about the transmission, symptoms, and prevention of these common diseases.

Giardia Lyme Disease Rabies West Nile Virus Eastern Equine Encephalitis Zika Virus

GIARDIA

Giardia lamblia is a common, single-celled parasite, which can cause an illness of the intestines known as Giardiasis. The disease can be found throughout the world and is widespread among mammalian, avian, and reptile species.

Giardia and Beaver

While there has never been a proven, documented case of a human contracting Giardia from beaver, the species has often been unfairly, and inaccurately, implicated as the source of Giardia contamination of fresh water resources.  Many studies claiming to have done so lack any scientific evidence in support of the claims. However, current research shows that contamination from humans is regarded as a more probable source. In fact, humans are now considered to be the most common reservoir, as they shed 900 million cysts per day.

Transmission 

Symptoms

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LYME DISEASE

The bacterium that causes Lyme disease can be spread to both people and animals through the bite of very small, infected ticks. These ticks require constant, high relative humidity at ground level, and therefore are most common in the northeastern and coastal states, the upper Midwest, and the Pacific Northwest. Lyme disease is most often spread during the late spring through the early fall season. Ticks live on low-lying brush and grassy areas, and subsequently crawl onto animals and people who come into contact with these plants.

Although people generally associate deer with Lyme disease, at least 27 species of mammals serve as efficient hosts for deer ticks, and over 125 vertebrate species serve as effective hosts for nymphs.

Transmission

  1. Animals that are infected with Lyme disease bacteria
  2. Ticks that can transmit the bacteria, and
  3. Animal hosts (such as mice and deer) that can provide food for the ticks in their various life stages.

Symptoms

Early Signs and Symptoms (3 to 30 days after tick bite):

Later Signs and Symptoms (weeks to months after tick bite):

Treatment

Prevention

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RABIES

Rabies is a much-feared disease of the nervous system that dates back to ancient times. Rabies was rare in Massachusetts for decades, appearing primarily in a very small percentage of bats. However, an outbreak of raccoon rabies, which originated in the Mid-Atlantic States in the late 1970s, made its way to New England. It is one of several strains of rabies impacting wildlife in the United States.

You cannot tell if an animal has rabies just by looking at it. Some infected animals may act strangely or aggressively, but others may not.

All mammals can contract rabies, but the current outbreak primarily affects raccoons, bats, skunks, foxes, and occasionally woodchucks. Birds, rabbits, opossums, squirrels, chipmunks, rats, mice, and other small rodents are rarely affected. Snakes, turtles, lizards, frogs, toads, salamanders, fish, and insects do not get rabies.

Despite the presence of these strains, rabies is still uncommon in Massachusetts.

Transmission

Symptoms

Treatment

If you are bitten or scratched by an animal:

If your pet is bitten or scratched by another animal:

Prevention

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WEST NILE VIRUS

West Nile Virus is a virus that causes encephalitis and is primarily transmitted to humans and other animals by mosquitoes and ticks while they feed.

From 2000 to 2008, the Massachusetts Department of Public Health collected reports and ran tests for West Nile on dead birds in Massachusetts to monitor activity across the state. In recent years, mosquito collection and testing has provided the most reliable indication of current activity and birds are no longer tested.

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EASTERN EQUINE ENCEPHALITIS

Eastern equine encephalitis (EEE) is a rare but serious disease caused by a virus identified in mosquitoes. Since the virus was first identified in Massachusetts in 1938, fewer than 100 cases have occurred. Over 60% of those cases have been from Plymouth and Norfolk counties. Outbreaks of EEE usually occur in Massachusetts every 10-20 years and typically last 2-3 years. The most recent outbreak of EEE in Massachusetts began in 2004 and included 13 cases with six fatalities through 2006.

 Transmission

Symptoms

Usually appear 3 to 10 days after a bite from an infected mosquito:

Treatment

 Prevention

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ZIKA VIRUS

Zika is a virus that is spread by the bite of an infected mosquito.  Most people infected with Zika virus do not get sick, but the virus can sometimes be passed from a pregnant woman to a fetus which may cause a serious birth defect of the child’s brain. On February 1, 2016, the World Health Organization (WHO) declared Zika virus a Public Health Emergency of International Concern (PHEIC) and pregnant women were advised not to travel to certain infected countries.

Transmission

Symptoms

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Prevention

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