Coccobacilliosis: A New Disease?
In the past few years there have been several cases of Coccobacterium infection causing disease in humans. There are two types of these infections, human and animal. Human infections usually result from eating undercooked or raw meat contaminated with Coccobacterium species. Animal infections are caused by ingesting infected soil or water. Humans may become ill after exposure to animals such as rats, mice, rabbits, squirrels and birds. Animals may carry the bacteria on their bodies and transmit them to humans through bites or scratches.
The first case of human coccidioides infection was reported in California in 1982. Since then there have been many additional reports of human coccidioides infection in other parts of the world. These infections often occur in immunocompromised individuals such as AIDS patients, those receiving chemotherapy, and those undergoing organ transplantation. Other factors which increase the risk of developing human coccidioides infection include having diabetes mellitus type 2 (DM2), being pregnant or breastfeeding, smoking tobacco products containing nicotine, and using alcohol during pregnancy.
Human coccidioides is most likely to affect the lungs and cause respiratory symptoms, but it can also affect the central nervous system (CNS) and cause meningitis, which is an infection of the fluid surrounding the brain and spinal cord.
The only animal known to transmit human coccidioides is the domestic dog. This was first reported in 2005. Since that time several other cases have been identified. While other animals probably can transmit human coccidioides, dogs are likely the main animal involved in transmission due to their close contact with humans and tendency to roam and scavenge.
The dog-coccidioides relationship poses a potential risk to veterinarians, veterinary technicians, dog handlers, dog groomers, and breeders.
Recently animal Coccidioides infection has been reported in animals other than domestic dogs. These reports are from outside the United States and include foxes, coyotes and bats. It is not currently known whether these animals can transmit human coccidioides to humans. If they can, transmission is probably rare.
Both human and animal coccidioides infections are rare. Without an increased risk of exposure, the general public does not have much to worry about coccidioides. The main risk factors for developing human infection are those that put you at increased risk of coming in contact with the organism. For people at high-risk, avoiding activities or conditions that increase your risk of exposure is advised.
These activities and conditions that put you at risk of coccidioides exposure include:
travelling to or living in a region where the organism is endemic (currently California, Arizona, New Mexico, and Nevada),
playing in the dirt, especially in hot weather or when you have cuts or abrasions on your skin,
planting or tending soil-bound crops or nurseries,
working in a dusty environment and not wearing proper respiratory protection (e.g. a dust mask),
owning or being around dogs, and
working as a veterinarian or working in a veterinary clinic.
Diagnosing coccidioides infection
Diagnosing human coccidioides infection is a slow process. Your doctor will perform a series of tests to rule out other infections before confirming that you do have coccidioides infection. Your medical history will be taken and a physical examination will be performed. Your doctor may take a tissue sample and send it to a laboratory to look for evidence of the organism.
If your doctor suspects that you have coccidioides infection, they may start you on a course of antibiotics. This is not common practice, but it is sometimes used in regions where coccidioides infection is very likely, such as the Southwest United States. These antibiotics are also used to prevent any secondary bacterial infection from occurring.
There is one specific type of blood test that can be used to diagnose coccidioides infection. This is the quantitative serum immuno-fluorescent antibody (FA) test. This blood test is not widely available, so unless you are in a region where this disease is common and your doctor feels this test is necessary, you probably will not have this test done.
If you have been exposed to and possibly infected with coccidioides, your doctor may start a course of antibiotics to prevent the disease from developing. These are the same antibiotics used to treat the infection.
Even if they do not start a course of antibiotics, your doctor may still advise you to take preventative measures against the disease. If you are in an endemic area, your doctor will likely advise you to wear protective clothing, such as a long-sleeved shirt, long pants, closed-toe shoes, and possibly even a dust mask if you are doing work that may stir up the dust and expose your skin, such as gardening or construction.
What is the prognosis of coccidioides infection?
Even when diagnosed with coccidioides infection, the outlook is good. Most patients make a full recovery and do not suffer any long-lasting effects. Before the advent of antibiotics, the fatality rate was high, though now with the correct treatment most patients make a full recovery. Severe or chronic cases may take longer to recover, and in some cases, a patient may suffer from after-effects such as scarring of the lung tissue or damage to the liver. Severe cases may require a patient to be placed on a respirator to assist with breathing and given IV fluids and medication.
How is coccidioides infection treated?
The preferred way to treat coccidioides infection is through the use of antibiotics. There are three drugs that are typically used to treat this condition: erythromycin, azithromycin, and clarithromycin. These drugs work by destroying the bacteria that is causing coccidioides infection in your body. It is important to take all the medication as prescribed, even if you start to feel better, as this will help your doctor ensure that the infection is totally gone and prevent a relapse. It may take several weeks for the drugs to be effective.
The length of time you will be taking antibiotics depends on your symptoms and how severe the infection is. If you have a mild case, you may only need to take the medication for a week or two. For more severe cases, treatment can last from several weeks to several months.
How is coccidioides infection prevented?
If you have recently been exposed to the fungus that causes coccidioides infection, the best way to prevent it is by taking preventative antibiotics. Your doctor will be able to advise you on this and give you a prescription if necessary.
In addition, if you are living in a region where the infection is common, your doctor may recommend that you wear dust masks while doing activities that may stir up the dust and expose your skin, such as gardening or construction.
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