Cooperating on Q Fever
Another surge in the number of cases of Q fever in people in the Netherlands has been reported. Prior to 2007, the average number of cases of Q fever per year in the country was only 15. In 2007 there were 192 cases, and last year there were 958 cases, making this the largest community outbreak of Q fever ever reported. At the beginning of May 2009, another jump in the number of cases - over 200 - was reported by the dutch newspaper de Volkskrant.
Q fever is caused by a highly infectious organism called Coxiella burnetii. The organism can be carried by many different animals, but particular sheep and goats, and sometimes cattle. Most of the time it does not cause a problem in these species, but it has been linked to abortions and abortion storms (i.e. when many animals in the herd abort in a short period of time). It can be shed in manure, urine and milk, but the largest numbers of organisms are found in birth fluids and tissues (e.g. aborted fetuses, placentae). When the tissues and fluid dry out, the organism can be stirred up into the air over short distances in dust. Humans are highly susceptible to C. burnetii, and inhaling even a single organism can cause infection. Most of the time people who get sick have signs very similar to the flu, but severe pneumonia and liver disease can develop in a small number of cases.
A definitive link between sheep and goats and the Q fever outbreak in people in the Netherlands has not yet been established, but it is highly suspected that many of the cases are associated with infected goats (and some sheep). In the last two years numerous outbreaks of Q fever have been reported on dairy goat farms and one dairy sheep farm in the Netherlands. This has lead to a cooperative arrangement between the Dutch agricultural ministry and the Dutch public health ministry - these two goverment branches have come together to help cover the costs of vaccinating sheep and goat herds in the country, in order to help stem the tide of disease and ultimately prevent more human cases. This is a great example of the "one medicine" concept, whereby groups on both the human health and agricultural/animal health sides are working together on this problem.
Manditory vacciation is now required for sheep and goats on larger farms in the hardest-hit areas, as well as any farms reporting any cases of Q fever since 2005, and any sheep or goats that have a "public function" (e.g. petting zoo animals or occupational therapy farms). It is very important that this last group is included under the manditory vaccination, as these animals have a large amount of contact with people. Steps have also been taken to improve hygiene, restrict spreading manure from sheep and goats, restrict visitors to infected farms, and to make abortion storms on sheep and goat farms reportable, so they can be investigated for Q fever. It will be interesting to see how effective these measures are at controling the outbreak in 2009.
More information on Q fever can be found in our archives.
Google goes green with goats
The burgeoning green movement has scored another victory at Google's Mountain View headquarters. The facility has fields around it that are cut periodically to control weeds and reduce fire hazards. Google has recently exchanged lawnmowers for a herd of goats. Someone is now paid to bring in a herd of about 200 goats which spends a week or so grazing the area. This provides fossil-fuel-free grass cutting and a source of food for the goats. It's also presumably much nicer to look out at a group of grazing animals than a noisy lawnmower.
This is another interesting example of attempts to "return to nature", at least to some degree. Another example is urban chickens, which are a topic of considerable debate in some cities (more on that in a later post). Any time there is the potential for increased contact with livestock, there is some increased risk of transmission of diseases from these animals, although this risk is likely pretty minimal with lawnmower goats. The main concern is shedding of potentially harmful microorganisms like Salmonella in the animals' manure. Sunlight does a good job killing many of these microorganisms, and the duration and density of grazing would minimize accumulation of manure in the fields. If human contact with the fields is minimal, the risks would be extremely low. It sounds like these fields are not heavily used by people, so it's less likely that Google employees will be exposed to anything harmful, compared to what the situation would be if they used the area for having lunch or lounging in the sun while on break. Q-fever is also a potential concern, but that's mainly a risk around the time of birth (called "kidding" in goats - no joke!), so they just need to make sure they're not using heavily pregnant goats in their lawnmowing team.
There's never a no-risk contact with animals (nor is there such a thing as no-risk contact with people), but slight increases in known or theoretical infectious disease risks are not necessarily a bad thing if the benefits outweigh the risks. There are also no blanket answers to many of the questions about infectious disease risks. For example, while I don't have any real concerns with the Google goats, I wouldn't want to see goats grazing in the yard of a daycare or preschool. In a case like this, however, I think it's a good experiment and it will be interesting to see what happens over time.
Q Fever - From goats to people (and pets!)
Q fever is an infection caused by the proteobacterial organism Coxiella burnetii. Although usually not very common, C. burnetii can be carried by sheep, goats, and cattle, as well as birds and even sometimes cats and dogs. Animals often show no signs of illness, although the infection sometimes causes miscarriage, particularly in sheep and goats. Coxiella burnetii is also transmissible to humans. People are much more susceptible than animals to disease from Q fever. Even so, only about 50% of individuals that become infected show signs of illness, which can range from flu-like symptoms to pneumonia and hepatitis (liver infection). About 1-2% of infections in people are fatal.
Infected animals shed C. burnetii in their stool, urine and milk, but the highest number of organisms are shed in birth fluids and placentae. Coxiella is able to survive very well in hot, dry soil, and when dust and dirt from contaminated areas are stirred up into the air, the organism can be inhaled. This is the most common means of transmission, although direct contact with an infected animal or its stool or urine can also transmit the disease. Transmission from drinking milk from an infected animal is very rare, but is more likely if the milk has not been pasteurized. Cats and dogs can be infected by and transmit C. burnetii in all the same ways (especially through birth fluids), but they very rarely get sick. Ticks can also transmit the disease.
Q fever is one of the most infectious diseases in the world. As little as one C. burnetii organism is enough to infect a susceptible person. There are a few things to keep in mind to help reduce the risk of being exposed to this pathogen:
- Only eat/drink pasteurized dairy products.
- The main risk from cats and dogs (especially cats) is when they give birth. If you have a cat or dog that has kittens/puppies, wear gloves if you have to touch the babies or any placentae. Afterwards, cleaning the area very thoroughly to physically remove any tissue or fluid residue is very important, because most disinfectants cannot kill C. burnetii. Always wash your hands thoroughly after handing newborn kittens or puppies.
- On dry, windy days, avoid farms or areas where sheep or goats are kept.
- Avoid sheep and goat farms during the lambing/kidding season.
