Rat-Bite Fever

You really do learn something new everyday!

So today I had a patient – 4 year old male with a 24 hour history of abdominal pain which woke him up in the middle of the previous night (he kept crying and pointing to his tummy, saying ‘ouch’ over and over again), associated with 1 episode of vomiting, and this morning when he woke up he had a fever (40 degrees) and was off his food and drink – Mum took him to the doctors, who diagnosed him (provisionally, I guess) with tonsillitis and sent him home with oral antibiotics (phenoxymethylpenicillin) the child had as yet only had 1 dose od this antibiotic but Mum felt he was being very difficult to feed/keep fluids down so was concerned, child still had an ongoing fever of 39.4. There was no history of any rashes, no cough but had a sniffly nose the last couple of days. Wetting nappies as per usual (a sure sign he was taking in enough fluids) but no dirty nappies today (not unusual for this patient to go x2 days without pooing) Upon my review he was a bit upset, and seemed to be in discomfort, despite having had some sickly sweet paracetamol a while ago to counter the fever.

He had a background of some degree of developmental delay due to a disorder that I do not want to disclose here, for patient confidentiality so this story is untraceable back to them. There were no other comorbidities.

On examination, the child was sitting in Mum’s lap, crying but was settling down when soothed. ENT exam revealed a slightly hyperaemic throat with enlarged tonsils, no exudate or discharge. He kept sticking his tongue out and wincing when he swallowed – pointing towards the possibility of odynophagia or painful swallowing. May explain the ‘off food and drink’ as may be too painful for him to swallow. The mother was giving him regular round the clock calpol though, so difficult to say. Ears were wax-laden and I could not visualise a tympanic membrane in either. Chest was clear to auscultation, no heart murmurs or other weird sounds on listening to the chest. Tummy was nice and soft with no palpable masses and child did not appear to be in discomfort when tummy was examined. He was moving all four limbs, neck seemed soft and his observations (vitals – heart rate, capillary refill/BP, respiratory rate, oxygen saturation on room air – were all within normal limits; all except the temperature, which was still high despite the calpol. I prescribed some ibuprofen. There were no rashes (did I already say that? Yes, that was history, this is examination) – Moving on…

I asked mum if he had been unwell prior to the waking up with the ‘ouches’ in the abdomen? She reported he had spent the weekend with Dad, where he had been bitten by a rat (!!!) on the right index finger – sure enough, on examining, his right index finger had a blackened almost shiny minuscule raised bit – an unmistakeable bite mark, on the distal end of the finger. Surrounding area was a bit reddened and slightly inflamed looking. On movement of the finger, hand, wrist etc, he did not seem to be in a lot of discomfort, though he wasn’t exactly happy I was poking and prodding him so much. There were no palpable axillary etc lymph nodes either – but he was a bit warm to the touch still, and when the temperature was rechecked it was 40 again! We quickly started some antipyretic measures while I quickly listed the differentials in my mind. A) It seemed very likely that the tonsillitis was not bacterial (probably) as a sniffly nose and the acuity and high grade of the fever pointed towards a viral upper respiratory tract infection. It could still be a bacterial infection, though, so I wasn’t going to stop the antibiotics. B) I could potentially/probably send the patient home, as even though they did not seem to be drinking too much, they seemed to be weeing as per usual, according to their wet nappies frequency, with advice to sort of force fluids, along with some adequate antipyretic advice and analgesia advice, with followup in the GP surgery, and that if situation worsens or any of the red flag signs appears, to come to A&E instead. C) could it be an infection spread by the bite of the rat? This last bit I honestly did not know – I had heard and studied about (and mcqsed!) about cat scratch disease and dog bites and human bites and tick bites, but I had never in the course of my 5 year study or almost 10 years as a doctor come across a rat bite – my curiosity piqued. I did what everyone does when they are confused about something – I want to say something impressive like ‘I discussed it with my seniors etc etc’ but in reality I … googled it! (I discussed it with my seniors after that, though, who very kindly reviewed the patient, and discussed it with the paeds registrar and admitted this patient to the hospital – the rationale being they still had a fever despite significant attempts by Mum and A&E staff.) But my google search was very fruitful, and I present to you a few bits and pieces about RAT-BITE FEVER (yes, sounds very impressive and a little icky, and it is!): (this information is courtesy of the CDC website, which is probably the most reliable and authentic information out there as it is so aptly named the Centres for Disease Control and Prevention!)

It is a bacterial infection, has two types of bacteria implicated in it: the spirilary (spirillum minus bacteria) type and the streptobacillary (caused by streptobacillus moniliformis) type. It is transmitted by either being bitten or scratched by infected rodents, or with regular handling of infected rodents even without being bitten, or due to ingestion of the pathogens in food/water that is laced with rat urine/feces. It is not contagious. Symptoms include invariably a combination of any or all of the following: fever, vomiting, headache, joint pains, muscle aches, headache, rash, ulcer at bite wound, swelling around the wound and swollen lymph nodes. Can we agree we are ticking off a lot of the boxes for rat-bite fever? Symptoms may begin within a few days of being bitten by a rodent, or may present a few weeks after the bite. Rash is usually maculopapular. There are certain people at risk – like if you have a rat fetish or handle them or keep them as pets or if your local rat population lives alongside your local human population. Penicillin is the treatment of choice – don’t ask me what it is when you are allergic to penicillin! Complications include meningitis, myocarditis, pneumonia and rarely death. *cue ominous music* Prevention is a) avoid rats! duh b)practise good hygiene c) do not put infected fingers into the mouth.

AND THIS IS WHERE IT ALL CLICKED FOR ME WITH REGARD TO THIS PATIENT – HE PROBABLY PUT HIS INFECTED RAT-BITTEN FINGER INTO HIS MOUTH – AND INGESTED SOME OF THE PATHOGENS – AND HE WAS CURRENTLY AN IDEAL CANDIDATE FOR TREATMENT FOR RAT BITE FEVER! Fortunately he was already on the treatment for it – the Paeds registrar concurred with our assessment and the patient was moved to the pads unit.

I reiterate: Learn something new everyday!