“Tick Fever” by Dr Dick Stockley / HEALTH FEATURE
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“Tick Fever” by Dr Dick Stockley / HEALTH FEATURE
In Europe, “Tick fever” usually means Lyme disease: a tick-borne disease caused by a spirochete, Borrelia burgdorferi. We don’t have it in Africa. We have a milder tick-borne disease in the same family, Borelia duttoni, rather alarmingly named after Jonathan Dutton who discovered and subsequently died from it about 120 years ago. Its common name is African tick-borne relapsing fever, and in general, it’s a lot less severe than Lyme disease. However, there are other Borelia species in Africa which are more severe. One species that is spread by both ticks and lice is Borelia recurrentis, which has high mortality. Good news: it’s rare, only common in South Sudan.
The other group of diseases commonly called tick fever are Rickettsia. There are about 10 different Rickettsia, some have quite well-known common names such as Rocky Mountain spotted fever, tick typhus, murine typhus, and scrub typhus, which is my favorite real name: Orientia tsutsugamushi. Sounds like a restaurant serving rice wrapped up in seaweed.
African tick bite fever is due to Rickettsia africae: R. africae is reported as “no deaths ever recorded.” However, there are other Rickettsia diseases in Africa. R. conorii causes Mediterranean spotted fever, also called “Kenya tick typhus,” which can be nasty and fatal.
Louse-borne typhus is often fatal, but again good news: the most severe of the typhus Rickettsial diseases are no longer seen in Uganda.
We certainly diagnosed African relapsing fever often enough in our patients from the history and simple blood tests. Studies using PCR show that the spirochete itself is only found on microscopy in a tiny percentage of cases with positive PCR. So, centers that have PCR will find cases: everyone else will miss it. I’ve not heard of anyone doing PCR for Borrelia, so it’s either diagnosed by clinical suspicion or missed. It classically causes a sudden high fever with all the other associated non-specific symptoms of joint pains, backache, and headaches. It lasts a few days, then antibodies kick in, and they get better. Then the bacteria change their antigens, and off it goes again with another sudden fever a week or two later. And it can carry on for 5 to 10 cycles: 5 or more days of fever, then better, and relapsing after a week or two. Which is why it’s called relapsing fever. Not to be confused with “undulant fever,” which has a similar recurring pattern but is due to brucellosis.
The reason why most people get better without getting the whole 3 months of relapsing fever is because many antibiotics will treat it. So, the first time someone gets a fever, they are told it’s malaria. Old docs like me will remember that before rapid tests made the diagnosis of malaria certain, every fever was diagnosed as malaria. I read a German study about 25 years ago that found the diagnosis of malaria was wrong in 95% of cases. When they looked carefully, they found around 20 different diseases as the actual cause of fever in these patients, including the different tick fevers. I also remember the CDC identifying yellow fever in that sudden epidemic a few years ago.
Their investigations in the affected district included testing blood samples for pretty much everything and again found evidence of past infection with the 20-odd different diseases that we know are common causes of fever in Uganda, but just not diagnosed. So, when they fail to get better with malaria treatment or if the rapid test is negative, the next default diagnosis is typhoid. Again, most cases diagnosed as typhoid aren’t typhoid, and the treatment given wouldn’t be effective if it was. But Borrelia is sensitive to most groups of antibiotics, so would be quickly eliminated by drugs given for typhoid. Or just antibiotics given on suspicion: so, they get better without it being diagnosed or recorded.
All species of Borrelia respond very well to doxycycline. So, our policy was if it looked like Borrelia and quacked like Borrelia, we would diagnose it on suspicion, give doxy, and see if they’re better in a couple of days. A lot easier than sending samples off for PCR-for-everything costing thousands of dollars and taking a week.
Rickettsia are also difficult to diagnose for certain. Most people think of typhus and the other Rickettsiae as the “spotted fevers,” but not every case has a rash. Like Borrelia, they can be just a fever with non-specific symptoms. A suggestive diagnostic sign is the eschar: a red area which scabs over with a black crust where the bite was. Borrelia bites can also cause a red lump for three days, but a true eschar strongly points to Rickettsia. All tropical fever diagnosis depends on the classic diagnostic process of history, examination, and simple lab tests. “Who, when, where.” Where has he been: central Kampala or a swamp in West Nile? Is he an accountant or a vet? How long after swimming in Jinja, camping in Karamoja, or walking in Murchison did the fever begin? Simple tests like a urine dipstick, a simple blood count, and the easy rapid tests will point in the right direction. History, examination, and simple tests will narrow it down to not malaria, not bilharzia, not dengue or one of the other arboviruses, and not a common focal bacterial infection. Instead, they might suggest Borrelia, Rickettsia, leptospirosis, Coxiella, or other common but missed febrile diseases are likely. The good news is they all respond very nicely to doxycycline.
A properly followed-up therapeutic trial of doxycycline is often the most sensible option. The key to quick diagnosis is common sense.
We all want to avoid massively expensive and time-consuming investigations, or avoid the trauma of unnecessary or painful treatment and injections. If you’re a long way from sensible and competent medical care, my advice is to always carry malaria rapid test kits, travel with doxycycline, and if you get a fever, look up old articles on The Eye website or The Surgery website. DIY diagnosis and treatment are never recommended but is often unavoidable: if you have to do it, be prepared and use your common sense. I also know if you email The Surgery, one of the tropical specialists there will guide you. If you’re told your fever is “clinical malaria,” but you know you have a negative rapid test (ask to see the strip, it’s your right), or typhoid (how would you get typhoid? Is your personal hygiene that bad?), or “bacterial infection” (which is not a diagnosis at all), then ask questions: modern medical training encourages us to listen to our patients and encourage them to voice their concerns. Use Google. If it doesn’t sound like common sense, look like common sense, or quacks like common sense, then it probably isn’t.
