The Dutch government said Thursday it will vaccinate all goats and sheep in the country against Q fever and kill many pregnant goats to rein in an outbreak that has caused the deaths of six people in 2009.
Q fever is a rare bacterial disease that can't be spread between people and usually causes only flulike symptoms.
An estimated 2,300 people contracted Q fever in the Netherlands this year, up from 1,000 last year and 168 in 2007.
Many animals can carry the bacteria, but contact with infected goats is believed to be the main source of human infections.
The ministry Thursday said it planned to slaughter all pregnant infected goats, which carry the bacteria in high concentrations. It was not immediately clear how many goats will be killed.
Most humans are infected between February and May, when goats and sheep give birth.
"There's nowhere external to turn to for expert advice, because it's a unique situation," said ministry spokesman Thijs van Son.
Q fever infections usually occur in a cluster in one year and then peter out the next. But the Dutch outbreak has been growing and spreading out over agricultural areas for three years despite increasingly strong measures to contain it.
That hasn't happened before, Van Son said, "not in Europe or anywhere else."
He said that so far the outbreak is not known to have spread to neighboring Germany or Belgium.
Van Son said one theory as to why the outbreak has been so severe in the Netherlands is the large numbers of animals per farm, combined with the density of the Dutch human population, which is one of the highest in the world.
In all there are around 1.2 million sheep and 400,000 goats on 350 farms in the Netherlands, a country of 16 million people.
The Dutch health ministry says 11 people in all have died from the diseases since 2007. All are believed to have had other underlying medical problems.
Q fever is known to present an extra threat for people with autoimmune diseases and with heart valve problems.
The Dutch government is researching whether an Australian human vaccine not yet approved in Europe could be used in the Netherlands.
Special measures are in place for a range of 5 kilometers (3.1 miles) at the 55 infected goat farms where the disease has been confirmed, including a ban on breeding.
The slaughtering program may be expanded, depending on the results of further tests and the vaccination program, Van Son said.
Agricultural organization LTO says it supports the measures announced Thursday, but argued for an attempt to distinguish between healthy and infected animals before slaughter.
"Killing healthy pregnant animals doesn't help reduce the number of sick people and it's not ethical," it said in a statement.