Erythema infectiosum is an acute viral illness caused by Parvovirus B19. It is usually a mild flu-like illness and produces a maculopapular rash, appearing initially on the cheeks and then spreading towards extremities. The rash usually spares the palms and soles and gives a slapped appearance to the cheeks. It can be described as having a fishnet appearance on the body.

Pale, bulky, malodorous stools are evidence of fat malabsorption syndrome. The diagnostic test is jejunal biopsy to rule out other differential diagnoses such as celiac disease, giardiasis or Crohn’s disease etc.

Because the medical history included tonsillitis followed by haematuria and hypertension, there is a strong suspicion of a case of post-streptococcal glomerulonephritis (PSGN). Patients with PSGN usually have serological findings showing depressed serum haemolytic component CH50 and serum concentrations of C3. Sometimes depressed C4 levels are also apparent, but not always, therefore, the answer to this question is: depressed CH50 level.

History is suggestive of a possible hearing impairment. As the baby is vocalizing and has normal motor development, an isolated hearing problem is possible. A hearing test will confirm the diagnosis.

From the given scenario, the extraocular muscle affected in the child is superior oblique muscle. Point to remember:All of the extraocular muscles are supplied by the oculomotor nerve (3rd cranial nerve), except superior oblique (trochlear nerve/4th cranial nerve) and lateral rectus (abducens nerve/6th cranial nerve).The superior oblique muscle causes the eye to move downwards and medially. The unopposed inferior oblique, in this case, causes the eye to deviate upwards and medially. Children tend to tilt their head (torticollis) to the side opposite to the affected eye with their chin down toward the shoulder, and their face turned away from the affected side to decrease the diplopia.

Foreign body aspiration (FBA) commonly occurs in children aged 1–3 years. FBA typically presents with sudden onset of coughing and choking, followed by stridor and dyspnoea. Obstruction of the larynx or trachea is a potentially life-threatening situation that causes severe respiratory distress, cyanosis, and suffocation. Most commonly, the foreign body (FB) becomes lodged in the main and intermediate bronchi| approx. 60% of FB are located in the right main bronchus due to the more vertical orientation compared to the left main bronchus. Reduced breath sounds on the one side only would not be explained by a tracheal obstruction as it would cause reduced breath sounds bilaterally and a more severe clinical picture.

Congenital cytomegalovirus infection causes: jaundice, hepatosplenomegaly, petechia, microcephaly, hearing loss and seizures.

The clinical picture suggests that the child is severely dehydrated. IV fluid bolus then IV maintenance fluids is the correct option.

Cystic fibrosis is a progressive, genetic disease. A defective gene causes a thick, sticky build-up of mucus in the lungs, pancreas, and other organs. In the lungs, the mucus clogs the airways and traps bacteria leading to infections, extensive lung damage, and eventually, respiratory failure. In the pancreas, the mucus prevents the release of digestive enzymes that allow the body to break down food and absorb vital nutrients. Since the digestive enzymes are not being made, the food is not completely digested making them bulky, smelly, and hard to flush away. Finger clubbing is a prominent feature of cystic fibrosis on most patients.

Administration of IV prostaglandin/PGE1 (e.g., alprostadil) is indicated in ductal-dependent CHDs until surgery can be performedMechanism: prostaglandin prevents the ductus arteriosus from closing → creates intentional shunt to allow mixing of deoxygenated with oxygenated blood.

A patient with Down’s syndrome is likely to be subfertile rather than infertile.Down’s syndrome:The clinical features of Down’s syndrome include:- Face: upslanting palpebral fissures, epicanthic folds, Brushfield spots in iris, protruding tongue, small ears, and round/flat face- Flat occiput- Single palmar crease, pronounced ‘sandal gap’ in the first interdigital space of the feet.- Hypotonia- Congenital heart defects (40-50%)- Duodenal atresia- Hirschsprung’s diseaseThe cardiac complications in these patients include:- Endocardial cushion defect (40%)- Ventricular septal defect (30%)- Secundum atrial septal defect (10%)- Tetralogy of Fallot (5%)- Isolated patent ductus arteriosus (5%)The complications that occur later in the life of the patient include:- Subfertility: Males are almost always infertile due to impaired spermatogenesis. Females, however, are usually subfertile and have an increased incidence of problems with pregnancy and labour.- Learning difficulties- Short stature- Repeated respiratory infections (+hearing impairment from glue ear)- Acute lymphoblastic leukaemia- Hypothyroidism- Alzheimer’s disease- Atlantoaxial instability

One of the most common congenital viral infections is cytomegalovirus infection. It is caused by herpesvirus type 5. The clinical features include failure to thrive, intellectual disability, epilepsy, and microcephaly. The most common clinical complication is sensorineural deafness. The drug of choice for the treatment of neonatal CMV infection is ganciclovir, an anti-viral drug that has shown to prevent deafness.

Epilepsy is a common paediatric neurologic disorder characterized by seizures of varying frequency and intensity. There are many childhood or infantile epilepsy syndromes that can be categorized as benign epilepsy syndromes as the child suffering from these usually outgrows them after reaching a certain age, and they do not lead to significant cognitive or physical impairment. Some of these may not need any treatment. Such benign epilepsy syndromes include benign rolandic epilepsy, Panayiotopoulos syndrome, Gastaut type-idiopathic childhood occipital epilepsy, and idiopathic photosensitive occipital lobe epilepsy. West syndrome, also called infantile spasms, is a serious infantile epileptic encephalopathy, characterized by multiple clusters of myoclonic spasms, and regression of the previous normally attained milestones. It is associated with severe cognitive and physical impairment, often leading to life long disability.

The physical features and developmental delay are the key aspects in the given scenario. The child in question shows features of gross motor and social developmental delay and has physical features indicative of Prader-Willi syndrome (hypopigmentation, esotropia, disproportionately small hands and feet, loss of central muscle tone and undescended testes). Children with Prader-Willi syndrome can present with failure to thrive until ,12-18 months, at which point, hyperphagia and obesity become more prominent. Other options:- Although Klinefelter syndrome can present with delayed development, undescended/small testes and reduced muscle power, the presence of small hands/feet, hypopigmentation and failure to thrive are not characteristic features. – Marfan syndrome presents with different physical features (arachnodactyly, cardio-respiratory complications and skin changes, amongst others) than those associated with Prader-Willi syndrome. – DiGeorge can manifest with developmental delay, hypotonia and feeding difficulties. However, this clinical scenario does not report any of the typical facial features, hearing abnormalities or cardiac abnormalities that are typically caused by DiGeorge syndrome. – Russell-Silver syndrome can cause developmental abnormalities, poor muscle tone and power (poor head control and muscle function), feeding difficulties and poor growth during the post-natal period and infancy. However, characteristic facial (small, triangular face, blue sclerae) and skeletal abnormalities (limb asymmetry, finger abnormalities) are not present. Therefore, Prader-Willi syndrome is the most appropriate diagnosis for this patient.Note:Prader-Willi syndrome is an example of genetic imprinting where the phenotype depends on whether the deletion occurs on a gene inherited from the mother or father: In Prader-Willi syndrome, it is the paternal gene that is deleted from the long arm of chromosome 15, while in Angelman syndrome the maternal gene is deleted. Prader-Willi syndrome can occur due to the microdeletion of paternal 15q11-13 (70% of cases) maternal uniparental disomy of chromosome 15.

Based on the clinical scenario, the most likely risk factor in this child to develop gallstones is sickle cell disease.Note:Haemolysis is the most frequent cause for gallstones in children and the likeliest cause because of his ethnicity would be sickle cell disease. The gallstones are pigmented which form from bilirubin. 70% of patients with sickle cell disease will develop gallstones| the prevalence of gallstones is related to the rate of haemolysis.Other options:- Gilbert’s syndrome: it is a common condition in which bilirubin glucuronidation (i.e. converting bilirubin into a water-soluble form) is affected. During times of stress (viral illness, fasting, etc.) there is an excess bilirubin production, and jaundice may develop. It is a benign condition but there is some evidence of an increased risk of developing gallstones. However, sickle cell disease is a more likely risk factor in this case.- Hereditary spherocytosis: Hereditary spherocytosis is a disease of the white population and is less likely to be the underlying cause in this case.- Male gender: After puberty, the incidence of gallstones is higher in women. Before puberty, the incidence is equal.- Obesity: Obesity is a risk factor for gallstones and is thought to be behind the rising incidence among young adults. Nevertheless, haemolytic states remain the most common reason for gallstones in children.

Unprotected anal or vaginal sexual intercourse with an infected individual is by far the most common (95%) route by which HIV is transmitted. Other options:- Blood transfusion is an extremely rare cause of HIV transmission in the UK. – While HIV can be transmitted from mother to baby either during birth or via breastfeeding, the transmission rate is only 5 – 20%.- Sharing contaminated needles does put individuals at risk of getting HIV, although public health measures are in place to reduce this risk. – Although HIV can be transmitted via this route, it is around ten times less likely to result in transmission than unprotected anal or vaginal intercourse with an infected individual.

The symptoms of excessive salivation and diarrhoea, along with hypotension, bradycardia, and bronchoconstriction, indicates excess parasympathetic nervous system activity. The patient is showing features of acetylcholine toxicity. Pesticides typically contain organophosphates that are potent inhibitors of acetylcholinesterase. This enzyme is responsible for the metabolism of acetylcholine. Acetylcholine is the neurotransmitter used in the neuromuscular junction, as well as at select points in the autonomic nervous system. The autonomic acetylcholine receptors can be nicotinic (more sensitive to nicotine) or muscarinic (more sensitive to muscarine). The most relevant receptors in this scenario are the muscarinic receptors as the majority are located in the parasympathetic nervous system smooth muscle, exocrine glands, and cardiac conduction system.Other options:- Accordingly, to cause the symptoms described, there must be an abundance of acetylcholine which stimulates the muscarinic receptors to enhance the parasympathetic effects. Therefore the reduction in the formation of acetylcholine option must be incorrect as this would produce the opposite effect. – Noradrenaline is the primary neurotransmitter in the sympathetic nervous system, and both answer options relating to noradrenaline would increase the neurotransmitter and potentiate the sympathetic nervous system effects, making them incorrect.Features can predict the accumulation of acetylcholine (mnemonic = SLUD):- Salivation- Lacrimation- Urination- Defecation/diarrhoeaCardiovascular symptoms include hypotension and bradycardia. The patient can show associated small pupils and muscle fasciculationManagement:- Atropine- The role of pralidoxime is still unclear – meta-analyses to date have failed to show any clear benefit.

Among the provided options, we would expect a normally developing 18-month-old child to be able to carry toys while walking.At 18 months, a normally developing child will show the following gross motor abilities:- walks with the feet slightly apart- runs carefully with the head held high- pushes and pulls objects around the floor- walks upstairs if the hand is held- kneels on a flat surface without support- carry toys while walking.Other options:- Intentionally kicking a ball is a skill typically acquired by 2.5 years, not 18 months.- Jumping with two feet together from a small step is usually acquired by 2.5 years, not 18 months.- Propelling a tricycle forwards by pushing with the feet on the floor is a milestone generally acquired by 2 years, not 18 months.- Throwing a small ball overhand without falling is a milestone for children aged 2 years, not 18 months.

Carbon monoxide is a colourless gas, which is toxic to animals. It has a high affinity for haemoglobin (around 250 times greater than oxygen). It combines with haemoglobin forming carboxyhaemoglobin, which decreases the oxygen-carrying capacity of the blood, leading to a left-shift in the oxygen-dissociation curve. CO is produced endogenously in limited amounts (0.4ml per hour), but the toxic levels are higher.

In an acute and severe asthma attack the child cannot complete sentences in one breath because they are too breathless. The O2 saturation is less than 92% and PEF is between 33-50% best or predicted. In children that are 2-5 years old, HR is more than 140 bpm and more than 125 bpm in those older than 5 years old. The RR in children between 2-5 years old is more than 40/min, and more than 30/min in those older than 5 years old.