Here’s The Lowdown on some selected tests.
Ross River Fever
Ross River Fever or Ross River Virus (RRV) sounds a bit far-fetched & exotic to many people. However, Most cases of Ross River Fever in Australia are reported from Queensland. In 2015 there were over 4000 notifications in Queensland alone.
It’s a mosquito-borne virus that is therefore most common during the summer months. The kangaroo & wallaby are the natural hosts – these animals are not themselves affected.
Camping outside is the obvious risk factor so ensure you are using proper anti mozzie-protection which we discuss at The Travel Clinic.
The incubation is around 7 to 9 days. The most common symptoms are:
- Acute onset of Joint Pains in around 95%. The pains come on both sides of the body. Most commonly involved joints are the fingers, wrists, elbows, and toes, ankles, knees.
- Joint swelling in 50%
- Tiredness in over 90%
- Rash in 50%.
RRV is confirmed with a blood test for the anti-RRV Antibody. Bear in mind that it takes around a week of symptoms before this antibody appears in the blood.
Poo! Dientamoeba & Blastocystis
Dientamoeba & Blastocystis are commonly reported on the latest generation of stool tests that are performed by the pathology providers.
Since 2014, stool samples are usually tested using a combination of culture and DNA Testing. Prior to 2014, the usual test was just a culture.
The DNA test “looks for” a battery of over 10 bacteria & parasites. The test is highly sensitive – like a DNA test at a crime scene. It’s not surprisingly, therefore, that the test is positive.
There are two parasites in particularly that are cropping up regularly on stool samples and that leave a dilemma about what to do with a positive result. These parasites are Dientamoeba fragilis & Blastocystis. Both are commonly found in Australians without any gastrointestinal symptoms (over 5% for each). So how do you know whether the patient with diarrhoea is harmlessly carrying the parasite in their stools, or whether the parasite is causing symptoms
A reasonable question to ask is: why do a test when you ignore a positive result?
For acute gastro symptoms, the test is done to make sure there isn’t anything like salmonella, campylobacter and other infections. When the test only shows up Dientamoeba or Blastocystis, then these are likely to not be causing any of the symptoms.
However, it’s not as easy as that. Dientamoeba & Blastocystis both sound very alarming. Dientamoeba sounds like “amoeba,” and the other one also sounds like a nasty parasite. The fact that they are called parasites in itself is concerning enough.
The GP will resolve this dilemma in two ways after discussion with you
- When there is persistent diarrhoea, treat the parasite with antibiotics and see if the symptoms resolve. They may have resolved on their own anyway – you’ll never know. It’s not as easy as that, however, as Blastocystis in particular is difficult to get rid of.
- Just ignore the result. There are increasing calls amongst medical experts to do just this with the recognition that half of all kids carry one of these two organisms.
It seems likely that testing for these organisms will fall by the wayside as it seems hard to justify why pathology companies should include normal environmental organisms in the same test as salmonella or campylobacter.
I inform patient up-front that they may get a report showing these two named parasites that may or may not be causing any symptoms.
How do I arrange a Lactose Tolerance Test?
Lactose intolerance is diagnosed formally on a Hydrogen Breath test which can be performed from around the age of seven. Lactose is one of the FODMAPS sugars and frequently implicated as a symptom trigger for people with IBS. Excluding lactose from the diet is often a good practical initial approach.
Formal testing of young children for lactose intolerance is problematic and usually only considered if the child is not putting on weight normally (failure to thrive). However, your doctor may recommend a lactose-excluding diet with subsequent re-introduction.