In the paediatric population, 30% of PUO will not reach a final diagnosis. However, in those cases, PUO is often a self-limited and benign episode. 

When a definitive diagnosis is reached, the majority of causes are related to infectious diseases (38%), followed by connective tissue disorders/autoimmune pathology (13%) and malignancies (6%).

At present, there is not a generic PUO work-up since this wouldn’t be efficient. Remember that more than ¼ of cases are benign and self-limited! 

In many cases, PUO is a consequence of a late diagnosis. Clinical history taking and careful physical examination are crucial to pick up subtle signs and guide the complementary tests and imaging. New signs and symptoms, which weren’t present on initial examination, can appear later on.

In the literature, retrospective studies have shown that when imaging requests are prompted by some examination finding, they are more likely to yield a positive result. 

Here’s a table with possible differential diagnosis based on clinical findings.

The speed of the complementary tests will depend on the general appearance of the patient. Empirical treatment with antibiotics can blur the microbiology results resulting in a delayed diagnosis. The empirical use of steroids can mask other pathologies and again delay the diagnosis. 

For the above reasons, clinicians should reserve empirical treatment with antibiotics or steroids to the sick patient based on clinical assessment.

In PUO, a detailed clinical history is the most important diagnostic tool that can guide all investigations. Instead of ordering random tests, ask more questions!

When taking the history, consider: 

• Characteristics of the fever: when did it start, duration and intensity. Note that this child had a previous febrile illness which can be part of the same illness. 

• Pattern of fever: there are several patterns of fever which can help with the diagnosis. If managed in an outpatient setting, ask the family to do a symptoms diary. From looking at the fever chart, the child has an intermittent fever pattern.

• Age of the child: PUO in young children is often caused by infections while in older children and teenagers tends to be caused by a connective tissue disorder or a malignancy.

• Associated symptoms and signs: headaches, vomiting and diarrhoea, rash, arthralgias, myalgias, bony pain, lymphadenopathies. They can be very subtle therefore a systematic review of all systems is necessary. 

• Systemic symptoms: fatigue, anorexia, weight loss, sweating.
• Previous medical history: a history of many bacterial infections can be related to a primary immunodeficiency. The most common primary immunodeficiencies are: 

1. Common variable immunodeficiency
2. Chronic granulomatous disease

Usually the immunodeficiencies are associated with complicated infections, failure to thrive, atopic disease or autoimmune disease.

For more information: https://dontforgetthebubbles.com/ent-infections-immunodeficiency/

• Vaccination history: patient is fully vaccinated as per UK protocol. This includes BCG due to risk factors (Parents are from a country where incidence of TB is > 40/100,000 or more). 

• Regular medications or any exposure to new medication (think about drug- related fevers).

• Family History: Ethnic background, consanguinity. Family is from India and there is no consanguinity. 

• Environmental risk factors: TB contacts, area where family lives, exposure to animals, vectors (mosquitos, ticks…), food intake (unpasteurised dairy products, uncooked meat and fish), international travels (place, malaria prophylaxis and compliance of prophylaxis). 

Patient travelled to India to visit grandparents when she was 9 months old. She was exposed to some mosquito bites.  She lived in an urban area for 3 months. Parents were not aware of any TB contacts.

For international travellers, the following website provides relevant information on potential risks and outbreaks occurring on each country: https://travelhealthpro.org.uk/

When a patient has received a provisional diagnosis plus empirical treatment for at least 48 hours and there is no improvement, clinicians should use a systematic approach to understand the reasons behind the poor response to treatment. 

Here are the four main questions to be answered: 

1. Is there a problem with the medication? 

The diagnosis is right but the problem is within the treatment. Issues with the treatment could be related to: 

-Drug resistances (MRSA, ESBL bacteria).

This website will provide a map with all antibiotic resistances over the world:  https://resistancemap.cddep.org/AntibioticResistance.php, treatments should, when possible, be guided by microbiological culture results.

-Underdosages of the antibiotics which don’t reach the effective concentration.

-Very virulent bacteria creating a toxin that requires more antibiotics (eg. Staph. aureus PVL) 

-Adherence to treatment (low compliance) 

-Malabsorption of medication (for example vomiting, diarrhoea when taking oral medications)

-The selected antibiotics are not reaching the right place of infection (bone, abscess…)

2. Are we targeting the wrong bug?

Antibiotics are mainly covering for bacteria but the actual infection can be caused by other microbes like viruses, atypical bacteria, TB, parasites and fungal infections. 

3. Is there a problem with the host? 

Consider whether the episode could be only a prolonged febrile syndrome for a common disease due to host problem.  The problem can reside in the immunity (immunodeficiencies), structural problems that can predispose to localized infections (for example a patient with previous abdominal surgery who now has an abscess) or whether the patient has a foreign body or a central catheter that can be the source of the infection.

4. The problem is not infectious: fever can be a sign of a tissue connective disorder, malignancies and other illnesses like a central origin related fever, drug related fever or a factitious illness.

This child has now had at least 12 days of fevers. It could be even longer if we consider that he had a febrile illness labelled as “viral” before this episode. 

On examination, the main clinical sign are the small cervical lymphadenopathies bilaterally with 1 small supraclavicular lymphadenopathy. This clinical finding could prompt the clinician to investigate for others cause: URTI, EBV, CMV, pneumonia, pleural effusion, TB, Bartonella, connective tissue disorders, malignancies, histiocytosis.

After 18 days of intermittent fever, cervical lymphadenopathies and some fatigue, the patient underwent a fine-needle aspiration of the supraclavicular lymphadenopathy. The histology showed a caseating granuloma and the microbiology sample showed acid fast bacilli. TB GeneXpert of the sample and culture were positive for non-resistant Mycobacterium Tuberculosis. Patient was diagnosed with tuberculous cervical lymphadenitis (extrapulmonary TB).

Probably not. Use of antibiotics can delay microbiological diagnosis since the blood cultures’ yield is decreased. If the patient has a good general appearance and fevers are well managed with PRN antipyretics, then clinician can consider withholding the antibiotics until a definitive diagnosis is reached. 

Reaching the definitive diagnosis: 
After 5 days of treatment with amoxicillin and azithromycin and no clinical improvement, basic investigations were repeated and further were added.

Bloods tests
WCC 22 x10⁹/L with neutrophils of 18 x10⁹/L,
Lymphocytes 4 x10⁹/L, CRP 36 mg/L
ESR >60 mm/h
Normal renal and liver function
Blood film normal: No reactive lymphocytes, no lymphoblasts seen
Blood cultures Negative.
CMV Serology: IgM negative, IgG Negative
EBV serology: IgM negative, IgG Negative

Microbiology
Mantoux /TST (Tuberculin skin test): 10 mm induration
(Patient received BCG vaccination)
IGRA (Interferon gamma release assay): Positive
Gastric aspirate for AFB smear: negative 
Gastric aspirate for TB GeneXpert: negative

Imaging
Repeated chest XR: similar features compared to previous one, peri-bronchial shadowing.
Ultrasound of lymph-nodes: several lymph-nodes with nodal matting and surrounding soft tissue oedema. Prominent vascularity in the hilum.

• Systemic symptoms 
• Supraclavicular lymph-node
• Firm and/or fixed lymph-nodes
• CXR changes, abnormal Full blood count or increased ESR
• Adenopathies > 1 cm in a neonate 
• Suspicion of TB 
• Persistent lymphadenopathies for more than 4 weeks despite antimicrobial treatment
• Sometimes in acute lymphadenitis if a patient is not responding after 48 hours of treatment

Infectious diseases: 

Osteomyelitis: 

Every time a patient presents with reduced range of movement due to a bony pain, osteomyelitis should be considered. In non-verbal children, it can present with irritability and inability to bear weight. It usually affects the metaphysis of the long bones (femur, tibia…). Therefore, the original diagnosis of clavicle osteomyelitis was quite rare. Now that the patient presented again with fever and a new similar problem after receiving adequate antibiotic therapy, another diagnosis should be considered. 

Septic Arthritis: 

It has a similar presentation to osteomyelitis but usually the joint is swollen, red and hot. Ultrasound of the joint can detect joint effusion which can be a sign of septic arthritis. Urgent orthopaedic referral for aspiration +- surgical washout is necessary. 

Connective tissue disorder: 

Transient synovitis: Fever and inability to bear weight can be a common presentation for transient synovitis. In this particular case, the initial diagnosis might have been wrong and the first inflammatory/infectious process could have triggered the production of antibodies causing inflammation over the joint. 

SOJIA (Systemic Onset of Juvenile Idiopathic Arthritis): Usually the joints affected by the arthritis are hot, tender and erythematous. We can suspect this pathology when there are different joints affected at different times. It is usually associated with systemic symptoms (fever and salmon pink rash, splenomegaly, serositis).

Diagnosis is made by elevated ESR, elevated ferritin, absence of antibodies, rheumatoid factor negative and exclusion of malignancy or infectious process.

CRMO (Chronic Recurrent Multifocal Osteomyelitis): this is an idiopathic inflammatory bone disorder with chronic multifocal bone pain. Sometimes systemic symptoms like fever can appear. Clavicle involvement is characteristic of this pathology.

Diagnosis is made by lesion’s biopsy: this will show an inflammatory reaction with no microbiological growth. 

Malignancies: 

Leukaemia: can present with bony pain and fatigue, lethargy and weight loss. Pancytopenia and blast can be seen in the blood film. LDH and uric acid are raised. Definitive diagnosis is reached with the bone marrow aspirate and flow cytometry.

Neuroblastoma: This is a malignancy that usually presents with abdominal mass. Sometimes mass can be found in the thoracic cavity. It appears in children below 5 years. The neuroblasts infiltrate the bone marrow. Therefore, patients can present with bony pain and pancytopenia. 

Diagnosis is reached by abdominal ultrasound and further imaging to evaluate the stage of the disease. Bone marrow aspirate is necessary along urine Vanillylmandelic Acid (VMA). 

Bone tumours (osteosarcoma /Ewing’s Sarcoma): 

Even though bone tumours are much less common than leukaemia and neuroblastoma, the presence of bony pain and prolonged fevers would prompt the diagnosis. LDH is usually elevated with raised calcium. 

X-Ray show bony abnormalities and further imaging with MRI or CT can provide more information. Sometimes biopsy of the lesion is necessary to confirm the diagnosis. 

Bone marrow is recommended in Ewing’s sarcoma. Metastasis and benign bone tumour should also be considered in the differential diagnosis.

Other: Histiocytosis:  this is a systemic illness which can affect bones. Associated symptoms are erythematous skin lesions, oral ulcers, lymphadenopathies, cough, shortness of breath, hepatosplenomegaly, malabsorption. Diagnosis is reached by seeing Langerhans cells in the biopsy of the lesion.

At this point, the patient has had a fever on and off for more than 3 weeks. A provisional diagnosis of osteomyelitis was made based on imaging findings. However, treatment is failing and the patient is now presenting with new symptoms (unable to bear weight). 

Repeated basic investigations:

If after the above investigations, the clinician does not reach a diagnosis, then: 

• Re-take a good clinical history 
• Re-assessment of the patient
• Withhold current medications
• Do specific imaging (XR/Ultrasound/MRI of the new affected area)
• Perform immunological studies: rheumatoid factor, ANA and anti-DNA antibodies, Immunoglobulins
• Perform a bone marrow aspirate and trephine for histology, cytology and microbiology.

In this case, the diagnosis of osteomyelitis was discarded. SOJIA vs Leukaemia were the 2 main differential diagnoses.  Discussion regarding therapeutic steroid treatment for SOJIA was raised. 

Usually in PUO, steroid treatment should be avoided until malignancy is ruled out.  Steroids are used therapeutically in many oncology protocols. The use of steroids in an unconfirmed case of leukaemia can improve symptoms but it can blur the histological picture required for the diagnosis and confuse the staging process. This would lead to a delayed and potentially incorrect treatment. 

It is crucial to perform a bone marrow aspirate before steroid treatment is given, especially if there are symptoms and signs compatible with malignancies. 

In the above case, the full blood count showed mild pancytopenia which can be related to a bone marrow infiltration. The peripheral blood film was normal. Finally, the patient underwent a bone marrow biopsy and this confirmed the diagnosis of T-cell ALL. 

PET-CT is an imaging technique that localises anatomical parts with high metabolic activity, detecting hidden infections, malignancies or any inflammatory foci. 

PET-CT has proven to be useful in patients with PUO who are generally unwell, sick-looking, since early diagnosis is urgent in those patients. Otherwise, PET-CT can be used in those patients who have had extensive investigations done, have not had clinical improvement and still no diagnosis has been reached.

You should probably start by repeating basic investigations. Results: raised WCC with neutrophilia and thrombocytosis. Hb 101 g/L, WCC 32 x10⁹/L with neutrophils of 24 x10⁹/L, Platelets of 961 x10⁹/L. He had normal renal and liver function.

Infectious diseases investigations: 

Microbiology cultures: Blood cultures were negative, even the prolonged culture for atypical bacteria. Stool sample was negative for viruses, bacteria and parasites. Urine sample became negative (previous sterile pyuria)

Toxoplasma serology:  IgG and IgM negative

CMV serology: IgM positive and IgG positive.  Second sample sent for CMV IgM negative. CMV PCR was negative. The initial positive IgM CMV was considered to be a false positive. IgM positivity in virology/microbiology assays may be non-specific, in patients with autoimmune diseases, cross-reactions.

EBV serology: IgM and IgG negative. 

Blood PCR for EBV, CMV and adenovirus negative.

Respiratory sample PCR: negative.

Lumbar puncture: LP was performed on day 14 of admission: WBC < 3/mm³. RBC <3/mm³. Viral PCR for enterovirus, parechovirus, mumps, VHS1&2 and VVZ negative. Negative culture.

Interferon Gamma Release Assay for TB negative. 

Inflammatory conditions investigations: 
Faecal calprotectin: negative. Since the patient had gastrointestinal symptoms and fever, Inflammatory Bowel Disease (IBD) should be considered as a potential differential diagnosis.

ESR: 50 mm/h.

Ferritin 222 ng/mL: important marker for inflammation. Especially high in Hemophagocytic lymphohistiocytosis /Macrophage Activation Syndrome.

Malignancies: 
Blood film: no atypical cells. Polychromasia and raised platelet count. Neutrophilia.

LDH 446 U/L (high)

Imaging
Day 12 Chest XR: normal
Day 13 Abdominal Ultrasound: normal kidneys and bladder. Normal liver, spleen, gallbladder and bile ducts. No abnormal masses or bowel wall thickening. Trace of fluid in right iliac fossa postoperatively. No fluid collection. 

The patient was clinically stable, so it was decided to wait and hold antibiotic treatment. The patient continued to have daily fevers up to 39°C. On day 14, he had one bilious vomit and became more lethargic therefore antibiotics were restarted (Piperacillin-Tazobactam and gentamicin). The following day, he underwent a Bone marrow aspirate and MRI under general anaesthesia with results as below: 

BMA: Trilineage haematopoiesis. No evidence of abnormal infiltration. No increased haemophagocytic activity. Appearances in keeping with a reactive marrow. Negative for AAFB, both microscopy and culture. 

Abdominal MRI:  There is moderate distention of the proximal small bowel with an apparent jejunal transition point due to ileus, adhesions or oedema from handling.  Some free fluid but no abdominal collections.  No retroperitoneal collection.  No bone marrow abnormality.

On day 16, he did not spike any temperatures.  After 48 hours (on day 18 of admission), he had an evening temperature of 38.5°C.

The patient had 2 episodes when he was apyrexial:

• the first one between day 9- 11 after antibiotics were escalated (Piperacillin-Tazobactam and Gentamicin (D7)) and after surgery under general anaesthesia (D8).
• The second afebrile period was on day 16-18 after being re-started on Piperacillin-Tazobactam and Gentamicin (D15) and after he underwent a procedure under general anaesthesia. 

In the first episode, the lack of fever was linked to a good response to antibiotics whereas in the second episode given the fact that a non-infectious condition was highly suspected as a differential diagnosis, the afebrile episode could be linked to the anaesthesia.

A very important investigation to perform in PUO is an echocardiogram to rule out infective endocarditis. In this case, there were no positive cultures or risk factors to point towards an infective endocarditis but it would be useful to rule out this disease. Echocardiography can also help to diagnose Kawasaki disease. In this particular scenario, it would be an incomplete case of KD. 

Reaching the diagnosis: 
On day 19, the patient had an echocardiogram which revealed dilated circumflex artery and an aneurysm of the left anterior descending artery. This finding confirmed the diagnosis of Incomplete Kawasaki. The ophthalmology review showed no pathological findings.  

In our particular case: the patient had prolonged fevers with high inflammatory markers (CRP, ESR, Neutrophilia), irritability without CSF infection, sterile pyuria, low albumin, anaemia, thrombocytosis and lack of alternative diagnosis. Furthermore, he had a characteristic echocardiographic finding of Kawasaki Disease.

Patient was started on IVIG and aspirin. Steroids were included in the treatment since the patient already had evolving coronary and or peripheral aneurysm.

For more information on criteria for steroid use in Kawasaki disease, you can read: Eleftheriou D, et al.Managment of Kawasaki disease. Arch Dis Child,99,1 2013 

With regards to the antibiotics, gentamicin was stopped while Piperacillin-tazobactam was continued while evaluating response to IVIG. Piperacillin-tazobactam was stopped after 48 hours. 

Kawasaki disease is rare but early diagnosis is important to avoid cardiological sequelae. Incomplete Kawasaki can present a clinical challenge to diagnose.

This is a very challenging patient. Due to their reduced ability to communicate and cognitive impairment, these children are difficult to assess. Furthermore, this patient is malnourished which increases the risk of infections. 

The above results showed a possible UTI which is in keeping with the clinical picture (high fevers, shivering in a patient with high risk of UTI due to his cerebral palsy and poor bladder control). Antibiotics were changed from amoxicillin to amoxicillin-clavulanic to give broader cover for gram negative bacteria (E. Coli, Klebsiella…).

To note, the patient has scabies which is a very common parasitic skin infection that affects mainly the palms and soles and the groin area. If the patient has been scratching over the genital area, it could have triggered a UTI. Furthermore, there are poor hygiene conditions in the area with limited access to water.

The slightly raised GGT and GOT was correlated to the use of phenobarbitone. The hepatitis B and C were negative but the hospital did not have the test for hepatitis A. Nevertheless, the clinical symptoms were not fitting with hepatitis A. 

The patient was treated with co-amoxiclav for 7 days. He initially improved and fevers were spacing in time. However, on day 9 he started again with very high fevers and shivering. He was looking unwell during the fever episodes so he was started on ceftriaxone IV. His baseline temperature was always raised, he had abnormal movements and was irritable. Temperature persisted despite treatment

Another urine sample was requested to rule out a UTI due to a resistant bacterium, since microbiological cultures were not available in the rural hospital. The urine microscopy was negative for WCC and urine dipstick did not show any abnormalities.

Another important differential diagnosis was meningitis. Patient was irritable, had abnormal movements and a fever. The abnormal movements consisted of small twitching of the arms while crying inconsolably. There were considered either shivering or behavioural but there was a lot of discussion if those movements could represent a seizure event. Furthermore, mother was unable to describe the usual seizures that he had at home. The team subsequently realised that there was an error with the regular medications: he was prescribed 100mg of phenobarbitone but mother clarified that at home he was taking 200mg, therefore his daily phenobarbital dose was increased to 200mg OD. To note, the patient did not have any devices (VP shunt) which could increase the risk of infections. In this rural setting, clinicians were not able to perform a lumbar puncture due to lack of laboratory equipment, so the patient was started on ceftriaxone high dose empirically. 

Pneumonia can be a common cause of infection in patients with cerebral palsy since they can have drooling, unsafe swallow prompting for aspiration. Usually, pneumonia in these children can be very silent. In addition, poor nutritional status can increase the risk of severe pneumonia. Patient was not desaturating or with respiratory symptoms but a chest XR was done (in a private clinic) and no lung abnormalities were detected. Furthermore, based on local antimicrobial resistances, the antibiotics he received earlier should have been covered for the most common bacteria causing pneumonia. Gastric aspirate for GeneXpert MTB/Rif was negative. 

Dental infections with abscesses can also present with fever and no other major symptoms. The patient had poor oral hygiene plus the lack of proper tongue movement, drooling and lack of routine dental care made him more prone to these types of infections. These infections are mainly due to anaerobes which should be covered by amoxicillin-clavulanic or ceftriaxone. On examination, no suspicious dental masses were found. 

Viruses can also cause non-specific symptoms. However, they shouldn’t last for very long. He did not have any gastrointestinal symptoms or respiratory symptoms. No palpable lymph-nodes. Unfortunately, in the hospital there were no laboratory diagnoses for viruses.  Full blood count differential was never lymphocytic. 

The most common parasites in this rural area are intestinal parasites (Giardia, Entoaemabeas) and blood parasites (Malaria). Entoaemebas can present with a dysentery which can cause fever. However, our patient did not have any diarrhoea. 

This area has a moderate risk of malaria, especially during the rainy season. Patients with malaria present with very unspecific symptoms: from fever with general malaise or headache and vomiting to seizures, coma and shock. Therefore, any patient with a fever in a tropical setting should prompt investigations for malaria. The most important element in the clinical diagnosis of malaria is a high index of suspicion. 

To reach the laboratory diagnosis, parasites should be seen or detected in blood. Blood film microscopy (thin and thick blood films) is the gold standard for malaria diagnosis, identifies the Plasmodium species and also quantifies the parasitaemia. However, in low resource settings, where microscopy is not always available or reliable, rapid diagnostic tests (RDT) are used to diagnose malaria. The RDTs detect Plasmodium antigens confirming the presence of parasites in the blood but don’t provide any information regarding the species or the parasitaemia. 

Patients with malaria can be classified into severe or non-severe malaria based on clinical and laboratory findings as per the WHO 2015 Malaria Guidelines. This classification is crucial as it will guide treatment. The most important complications of malaria infection in children are cerebral malaria, severe anaemia, respiratory distress due to acidosis and hypoglycaemia. 

Patients with severe malaria should receive parental antimalarial treatment with Artesunate and supportive management followed by a full course of oral artemisin combination therapy (ACT). Patients with non-severe malaria can be managed with oral antimalarial medication. 

On admission, the initial blood film was negative for haemo-parasites. Repeat blood films and a Malaria RDT (rapid diagnostic test which detects Plasmodium falciparum antigens in blood after 20 minutes) were requested. Repeat Blood film revealed presence of Plasmodium falciparum trophozoites with a parasitaemia of 2%. 

So the patient was diagnosed with Severe Malaria given the suspicion of CNS involvement and started on IV Artesunate. The patient had a good clinical response with resolution of fever and completed a course of oral Artemisin combination treatment (Artemeter Lumefantrine). However, after one week, the fever reappeared. This time, it was a low-grade fever with maximum peaks at 38.5. Repeat blood tests were normal. 

Malignancies: In this case, blood film did not reveal any blasts, chest XR was normal and abdominal ultrasound did not reveal any masses. BMA was not available locally and since the patient was otherwise well, this was not considered necessary. 

Connective tissue disorders: 

SOJIA, AR are very uncommon but still a differential diagnosis of persistent fever. In this setting, no resources were available for auto-antibodies testing, therefore clinical findings are the main way of diagnosing it. Since the patient did not have any rash, arthritis… this diagnosis was not considered. 

Acute Rheumatic Fever (ARF): this condition is quite common in low resource countries due to increased risk of streptococcal tonsillitis due to poor hygiene, overcrowding, poor accessibility to health facilities, fake drugs…  Acute rheumatic fever is an illness caused by an inflammatory reaction to streptococcal infection. It causes an acute, generalised inflammatory response. This illness targets specific parts of the body including the heart, joints, brain and skin. ARF typically leaves no lasting damage to the brain, joints or skin, but can cause persisting heart damage.  Our patient did not meet the Jones’ Criteria of ARF. 

Miscellanea (other possible causes of fever): 

Central origin fever: children affected with cerebral palsy or other neurological disorders relatively often present with chronic intermittent febrile episodes persisting for months. These episodes are not related to any infections but are actually arising from an abnormal thermal regulation resulting from the brain injury.

Hyperthermia from severe dystonia: children with cerebral palsy with dystonia can present with fevers and elevated basal temperature associated with elevated creatinine phosphokinase levels. 

Drug related fever: medications can trigger fevers. Common medications used in cerebral palsy are anticholinergic drugs (e.g. hyoscine) which can provoke unwanted fevers as a side effect. In addition, withdrawal of medications can present with fever (baclofen withdrawal syndrome). 

Lastly, factitious fever is a very challenging diagnosis. Sometimes admissions to hospital and close measurement of fevers plus observation of patient and carer interaction is as important as complementary tests. 

After 2 months of intermittent fever, it finally stopped. Basal temperature was always slightly elevated. Patient was diagnosed with central origin fever.

 The majority of PUOs are caused by: 

A: Malignancy

B: Connective Tissue Disorder 

C: Infections

D: Other diagnosis

E: Unknown diagnosis

The correct answer is C.

Infectious diseases are the main cause of PUO (about 38%), especially in younger children. No diagnosis is reached in 30% of cases but these tend to be benign and self-limited. This is followed by connective tissues disorders (13%) and Other diagnosis (13%). Lastly, malignancies are very uncommon but very important to consider given the severity of the disease.

A patient admitted to your hospital has been spiking fevers every day for 12 days. No other clinical findings are present. What is your next step? 

A: Repeat basic investigations, re-take clinical history, re-examine the patient, perform a Bone marrow aspirate.

B: Repeat basic investigations, re-take clinical history, re-examine the patient and do adequate imaging depending on clinical findings.

C: Perform a PET-CT to localise the pathology.

D: Perform autoimmune studies.

E: Perform a bone marrow aspirate.

The correct answer is B.

In many PUO cases, clinical findings are very subtle and can appear days after the fever. Therefore, re-taking the clinical history and re-examining the patient carefully is key to guide the complementary tests.

A Turkish 5-year-old girl presented with high fevers, profuse night sweating for 21 days.  Clinical detailed history revealed that parents are not consanguineous. She doesn’t have any relevant past medical history. She is fully vaccinated. The whole family was in Turkey for 2 months over the summer holidays. They were living in a farm in rural Turkey where they had goats, cows and chickens. They were drinking fresh milk from the cow. Based on the history, what diagnosis would you consider? 

A: Tuberculosis 

B: Bartonella (Cat-scratch)

C: Brucellosis

D: Toxoplasmosis

E: Lyme disease

The correct answer is B.

Brucellosis is a zoonotic infection caused by ingestion of unpasteurized milk from infected animals. It is also known as the Mediterranean fever. It is caused by a bacterium called Brucella melitensis. The main symptoms are fever, profuse sweating and joint and muscle pain. 

An unaccompanied asylum seeker from Uganda has just arrived in the UK. He refers to being a 12-year-old. He has had fevers for a prolonged time. On examination, he has splenomegaly. Blood tests revealed pancytopenia. Blood film is negative for malaria. HIV and hepatitis B, C negative. He said that in his country many people have these symptoms and they call it Kala-azar. What kind of tropical infection is he referring to? 

A: Visceral Leishmaniasis 

B: Schistosomiasis. 

C: Non falciparum malaria 

D: Visceral Larva Migrans

E: Echinoccocus granulosus

The correct answer is A.

Kala-azar is the local term for Leishmaniasis. This is a parasitic disease spread by the sand-fly. Main symptoms are fever, enlargement of spleen and liver and pancytopenia. Leishmaniasis is the second-largest parasitic killer in the world after malaria. Diagnosis is made by histological finding of amastigotes on spleen aspiration/bone marrow aspiration and RK39 Antigen detection.