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Duck influence on Influenza

8/28/2011

There are many different subtypes of Influenza A virus in nature. Surveys of waterfowl populations in the 1960’s and 1970’s showed that waterfowl including ducks harbor all of these different subtypes of the virus.

Ducks and geese are natural carriers or reservoir hosts of the influenza virus. A carrier usually means the animal does not appear ill, and remains unharmed despite the virus replicating in the animal. This natural resistance is genetic based and recent studies point to at least one candidate duck gene that helps prevent disease in the duck.

The path to influenza virus infection in humans involves a number of steps including transmission of the virus from ducks to chickens, mutation of the virus, reassortment, and adaptation in humans. Chickens are infected, become ill and often die. They act as amplifying hosts and spread the virus to humans. Breaking this chain of events by making chickens more resistant to the virus has been recently demonstrated.

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Bees are dying!

8/22/2011

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Colony collapse disorder (CCD) is a relatively new phenomenon that affects many different species of bees. All flowering plants need bees to survive. Bumblebees (genus Bombus) are close relatives of honey bees (genus Apis) and many species of both bees are dying.

What is killing them? Everything from fungi, viruses, pesticides to cell phones have been implicated in their deaths which is often seen as an abandonment of the hive as bees seemingly go off to die. Specific causative agents include mites, the fungus Nosema apis, Israel acute paralysis virus, Invertebrate iridescent virus, the pesticide clothianidin, and cell phone radiation to name a few. While there may be multiple causes or perhaps combinational effects, it is unclear if there is any commonality among these deaths. None of the mentioned pathogens are infectious for humans.

Make no mistake about it, without bees, it will be a less colorful and fruitful world.

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Where has that mosquito been poking?

8/5/2011

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One Health Concept--Wildlife, domestic animal, human and ecosystem health are linked.
Most people don’t think twice about smashing a mosquito that has just inserted its proboscis into your skin. Fewer people think about where that proboscis has been before. Female mosquitoes need a blood meal from a vertebrate in order for her eggs to develop properly. And those vertebrates include everything from humans to birds to alligators and snakes. Granted some mosquito species prefer certain hosts over others, but it many areas of our country that mosquito sucking your blood likely was feeding on a bird before that. Birds, small mammals, and some reptiles are part of what scientists call the sylvatic (wildlife) cycle involving mosquitoes and viruses. Diseases with names like West Nile, LaCrosse Encephalitis, and Eastern Equine Encephalitis involve birds that become infected when a mosquito takes a blood meal. The virus circulates in the blood of the bird and can be picked up by another mosquito when it feeds. There needs to be enough virus particles in the blood for the mosquito to become a carrier or a vector. This is referred to as the threshold of infection. Therefore, transmission from bird to mosquito to bird and so on leads to amplification of the amount of virus in the ecosystem.

Do birds become sick? It all depends on the virus and how long the virus has been associated with the bird. For example, West Nile Virus (WNV) has been shown to infect over 385 species of birds. Some birds are more susceptible to virus than other birds. The American Crow is one of the most susceptible and is often used as a sentinel for WNV presence in the area. Dead crows in late summer may indicate WNV activity.

If a mosquito takes a blood meal when the number of virus particles (virions) is high, the mosquito becomes infected. Later, she is looking for another blood meal and heads toward your arm. When she injects her anti-coagulant, she also injects some WNV particles into your arm. There is a good chance that you will not become infected, but of those who do only about 1% will show any signs of the disease. The only way for the rest of us to know if we have been infected at some time is to look for antibodies to the virus in your blood.

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First Post!

8/4/2011

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Start blogging by creating a new post. You can edit or delete me by clicking under the comments. You can also customize your sidebar by dragging in elements from the top bar.

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Duck influence on Influenza

Bees are dying!

Where has that mosquito been poking?

First Post!

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