Local

By Cindy Horswell

January 26, 2014

Texas, which has long campaigned for family pets to be vaccinated against rabies, is now attacking from the sky one of the state's foulest carriers of the disease: skunks.

Skunks would obviously put up quite a stink if caught and hauled in to a veterinarian's office for shots. So the state health department is taking the rabies vaccine to the vermin.

Twin-engine airplanes this month are crisscrossing 8,800 square miles of East and Central Texas to drop 1.2 million vaccine packets.

Each vaccine is the size of a fast-food ketchup packet and is coated with smelly fish meal to entice skunks to eat it.

Packets will rain down at a rate of about 150 per square mile, as pilots try to evenly disperse the vaccines over rural portions of Montgomery, Fort Bend, Waller and 14 other counties to the west and north of Houston.

The massive airdrop - which should skirt around residential neighborhoods - is part of an expanded test by the Texas Department of State Health Services of the V-RG vaccine - the same preventative used over the past two decades to nearly eliminate the canine and fox strains of rabies.

"We want to know if it will be just as effective in wiping out the skunk strain as it did the other two," said Tom Sidwa, state public health veterinarian.

The skunk strain is causing a majority of the state's rabid animal cases, Sidwa said. The second most prevalent strain comes from bats, he said, adding there is no known vaccine for rabies carried by bats.

Rabies, caused by a virus that infects the central nervous system in mammals, is almost always transmitted through the bite of a rabid animal.

If the skunk packets work as intended, hundreds of family pets and livestock will be spared from contracting the viral disease each year.

Safe, but use caution

The U.S. Department of Agriculture conducted studies on the oral vaccine and found it was not harmful to humans if they happened to touch one of the plastic-covered packets. Additionally, the studies found the packets are safe for ingestion for 60 animal species, including dogs and cats.

Each packet has a printed message that warns people to keep away: "Rabies vaccine, live vaccinia vector, do not disturb."

That's because inside each vaccine packet is 2 milliliters of pink liquid which contains a portion of a live virus. If swallowed or somehow otherwise absorbed by pregnant women or those with chronic health conditions, there could be some health issues, said Laura Robinson, director of the state's oral rabies vaccine program.

State officials said in the 20 years that vaccines have been airdropped, no one has complained of the packets causing any harm to humans.

People are also advised not to handle the packets because the human scent can make wildlife less likely to eat them, said Christine Mann, spokeswoman for the state health department.

Over the past couple of years, the state has attempted a much smaller pilot test of the skunk vaccine. Packets were spread over a few 200-square-mile plots in Fort Bend County in 2012 and then some similar plots in Waller County last year.

"But in order to determine the effectiveness of the vaccine, you have to capture skunks and collect their blood samples to see if they've developed the rabies antibody," Robinson said. "But they proved difficult to trap."

Robinson said her group never trapped enough skunks to form any conclusions on the success rate of the vaccine.

So this time, the study has been expanded to a broader area.

"We're hoping with this dispersal to catch and test a hundred skunks. If we get more, that would be great," she said.

Controlling outbreaks

The vaccine airdrops were first initiated in Texas in 1995 after then Gov. Ann Richards declared a "state health emergency" to fight the two worst rabies outbreaks the state had seen.

An outbreak of the canine strain began in the Rio Grande Valley in the late 1980s and spread within 40 miles of San Antonio, killing two people and necessitating thousands of post-exposure shots.

Before the outbreak was brought under control, a 14-year-old boy died after contracting rabies from a puppy he had been given. The pup died a few days after it was born.

Not long after the canine scare, the gray fox epidemic began in west central Texas and grew to involve 53 other counties.

As a result of the outbreaks, Texas became the first U.S. state to use the V-RG vaccine for a statewide application on rabid foxes and coyotes. It had previously only been tested on rabid raccoons on the East Coast.

Now, the state only does maintenance airdrops along the border with Mexico to prevent the re-emergence of the canine strain. Robinson said there has not been a single case of the canine strain reported in Texas since 2004.

The state does spot drops wherever isolated cases of the fox strain might reappear. No cases related to the fox strain have been reported since mid-2009, authorities said.

A 16-year-old Humble High School football player, infected by a rabid bat in 2006 that flew in through his bedroom window, was the last known Texan to die from rabies.