Infectious Disease and Microbiology: Influenza




Influenza is an acute viral respiratory infection caused by influenza viruses, typically presenting as a self-limited illness but capable of causing severe or life-threatening complications in vulnerable populations. While most healthy individuals recover fully, high-risk groups—including the elderly, young children, pregnant women, and those with chronic medical conditions—are more likely to develop complications such as pneumonia, respiratory failure, or death.


Influenza is highly prevalent worldwide, affecting approximately 5–20% of the population annually. Seasonal outbreaks occur predominantly during the winter months, often referred to as “flu season.” In the United States, influenza is responsible for tens of thousands of deaths and hundreds of thousands of hospitalizations each year. Occasionally, pandemics arise when new subtypes of influenza A viruses emerge, often due to major genetic changes, allowing rapid global spread with little preexisting immunity in the population.


Transmission occurs through respiratory droplets, direct contact with infected individuals, or contaminated surfaces. Viral shedding begins early—often within the first day of infection—and continues for about 5–10 days, though children may shed the virus longer. Preventive measures include good hand hygiene, respiratory etiquette, and especially annual vaccination. Vaccination is recommended for all individuals older than 6 months, with particular emphasis on high-risk groups. Two main vaccine types are available: inactivated vaccines given intramuscularly and live attenuated vaccines administered intranasally.


Influenza viruses are RNA viruses belonging to the Orthomyxoviridae family and are classified into types A, B, and C. Types A and B are responsible for most seasonal epidemics, while type C typically causes mild disease. Influenza A viruses are further subtyped based on hemagglutinin (HA) and neuraminidase (NA) surface proteins. Antigenic drift (small mutations) leads to seasonal variation, whereas antigenic shift (major genetic reassortment) can result in pandemics. The virus infects respiratory epithelial cells, and symptoms are largely due to the host immune response, including the release of proinflammatory cytokines, which may lead to severe complications such as cytokine storm and multiorgan failure.


Clinically, influenza is characterized by abrupt onset of fever, cough, nasal congestion, myalgia, headache, and malaise. The sudden onset of fever and cough during influenza season is highly suggestive of the disease. In some cases, especially in high-risk individuals, complications such as bacterial pneumonia may develop several days after initial symptoms, often indicated by recurrence of fever and worsening respiratory symptoms. Severe cases may involve exacerbation of underlying conditions like asthma or heart failure, as well as rare complications such as encephalitis, myocarditis, rhabdomyolysis, or shock.


Diagnosis is confirmed through laboratory testing of respiratory specimens. Reverse transcription polymerase chain reaction (RT-PCR) is the most sensitive and specific test and provides rapid results. Rapid antigen tests are also available but are less sensitive, especially in adults. Imaging such as chest X-ray may be necessary in severe cases to assess for pneumonia or other complications.


Treatment includes antiviral medications and supportive care. Neuraminidase inhibitors such as Oseltamivir and Zanamivir are effective against both influenza A and B and are most beneficial when started within 48 hours of symptom onset. They are especially recommended for high-risk patients or those with severe disease. Older drugs such as amantadine and rimantadine are less commonly used due to resistance. Supportive care includes rest, hydration, and management of symptoms.


In hospitalized patients, severe influenza may require intensive care support, including oxygen therapy, mechanical ventilation, or extracorporeal membrane oxygenation in cases of respiratory failure. Early antiviral treatment is recommended for hospitalized patients regardless of the duration of symptoms.


The prognosis for most individuals is good, with complete recovery expected. However, influenza can lead to serious complications, particularly in high-risk groups. These include bacterial pneumonia (commonly due to Streptococcus pneumoniae), acute respiratory distress syndrome (ARDS), myocarditis, and neurologic complications such as encephalopathy or Guillain–Barré syndrome. Vaccination and early treatment remain key strategies in reducing morbidity and mortality associated with influenza.

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Infectious Disease and Microbiology: Intraabdominal Abscess




An intraabdominal abscess is a localized collection of microorganisms, inflammatory cells, and pus enclosed within a fibrous capsule in the abdominal cavity. These abscesses may form within the peritoneal cavity, inside abdominal organs such as the liver or spleen, or in retroperitoneal spaces. They can also extend into adjacent areas like the pelvis or psoas muscle. Based on location, intraabdominal abscesses are classified as intraperitoneal, visceral, or retroperitoneal.


Epidemiologically, intraabdominal abscesses are more common in men and typically occur between the third and fifth decades of life. Most abscesses are located in intraperitoneal or retroperitoneal spaces rather than within organs. Common causes vary by age group and condition; for example, appendicitis is a major cause in children, while postoperative complications are more common in adults. Patients with diabetes, immunosuppression, malignancy, or conditions like pancreatitis are at increased risk. Certain infections, including fungal infections such as Candida, may occur more frequently in immunocompromised individuals.


The pathophysiology usually involves the دخول of enteric organisms into the peritoneal cavity through disruption of the gastrointestinal tract, such as perforation, inflammation, trauma, or surgery. This leads to localized infection, inflammation, and abscess formation. Both aerobic and anaerobic bacteria often act synergistically. Common causative organisms include Bacteroides fragilis, Enterobacteriaceae (such as Escherichia coli), streptococci, enterococci, and sometimes fungi like Candida. The exact pathogens depend on the source and location of the infection.


Clinically, patients often present with nonspecific symptoms such as fever, abdominal pain, nausea, vomiting, malaise, and sometimes signs of sepsis. The presentation varies depending on the location of the abscess. Liver abscesses may cause right upper quadrant pain and systemic symptoms, while splenic abscesses may present with left upper quadrant pain. Perinephric abscesses often cause flank pain that may radiate to the groin. In elderly patients, fever of unknown origin may be the only presenting sign, making diagnosis challenging.


Diagnosis relies on a high index of suspicion and appropriate investigations. Laboratory findings may include leukocytosis, abnormal liver function tests, anemia, and sometimes bacteremia. Imaging plays a crucial role, with computed tomography (CT) scan being the most sensitive and widely used modality. Ultrasound is also useful, especially for liver and kidney abscesses. Definitive diagnosis is often achieved by aspiration of abscess contents for microbiological analysis, which helps guide targeted antimicrobial therapy.


Management of intraabdominal abscesses involves three key components: control of the source of infection, administration of appropriate antimicrobial therapy, and drainage of the abscess. Broad-spectrum antibiotics are initiated empirically and later tailored based on culture results. Common regimens include combinations that cover both aerobic and anaerobic organisms, such as cephalosporins with metronidazole, carbapenems, or beta-lactam/beta-lactamase inhibitor combinations. Antifungal therapy is indicated when fungal pathogens are identified.


Drainage of the abscess is essential and can be achieved either percutaneously under imaging guidance or surgically. Percutaneous drainage is preferred when feasible, but surgical intervention is required in cases where drainage is not possible, the abscess is multiloculated, or there is failure to respond to conservative treatment. Some cases, such as small or specific types of abscesses, may be managed medically under close monitoring.


Patients with severe infection may require hospitalization, fluid resuscitation, and intensive care support if septic shock develops. Ongoing care includes close monitoring, follow-up imaging, and addressing underlying conditions such as biliary disease, malignancy, or urinary tract abnormalities. Preventive strategies focus on early diagnosis and management of intraabdominal infections and prompt treatment of conditions like appendicitis or diverticulitis.


The prognosis depends on early recognition and effective management. Mortality rates remain significant, particularly for splenic and hepatic abscesses, especially if diagnosis is delayed. Prompt treatment with antibiotics and adequate drainage significantly improves outcomes.

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Emergency and Acute Medicine: Vomiting (Pediatric)




Pediatric vomiting is a forceful, coordinated expulsion of gastric contents through the mouth, involving the phases of nausea, retching, and emesis. During vomiting, there is sustained contraction of the abdominal muscles and diaphragm, while the pylorus and antrum contract simultaneously. Unlike adults, vomiting in children—especially neonates and infants—requires a high index of suspicion for serious pathology, as it may be the first sign of life-threatening disease.


The etiology of pediatric vomiting is broad and age-dependent, encompassing gastrointestinal, metabolic, neurologic, infectious, and feeding-related causes. Gastrointestinal causes include conditions such as Hypertrophic pyloric stenosis, Intussusception, and Midgut volvulus, all of which may lead to obstruction and require urgent intervention. Metabolic causes include inborn errors of metabolism and diabetic ketoacidosis, while neurologic causes include intracranial hemorrhage, tumors, or hydrocephalus. Infectious etiologies such as gastroenteritis, urinary tract infections, pneumonia, and sepsis are also common. Feeding-related issues, including overfeeding or milk allergy, are particularly relevant in infants.


Clinical presentation varies depending on the underlying cause, but assessment of vomiting characteristics is critical. Nonbilious vomiting suggests obstruction proximal to the pylorus, whereas bilious (green) vomiting indicates obstruction distal to the ampulla of Vater and is a surgical emergency until proven otherwise. Bloody vomiting may indicate upper gastrointestinal bleeding, while “coffee-ground” emesis reflects digested blood. A feculent odor suggests distal bowel obstruction or peritonitis. Projectile vomiting in a 2–6 week old infant is classic for hypertrophic pyloric stenosis, while sudden onset vomiting with abdominal distention and systemic illness may suggest volvulus or intussusception.


On physical examination, clinicians should assess hydration status, vital signs, and overall appearance, as children can deteriorate rapidly. Signs such as tachycardia, poor perfusion, altered mental status, or shock indicate severe illness. Abdominal examination may reveal distention, tenderness, masses, or peritoneal signs suggesting obstruction or perforation. Additional examination should include evaluation of the genitourinary system (e.g., testicular torsion) and neurologic status.


The diagnostic workup is guided by clinical suspicion and aimed at excluding life-threatening causes. Laboratory studies may include glucose, electrolytes, and infection markers (CBC, cultures). Imaging plays a key role: abdominal radiographs can identify obstruction or perforation, while ultrasound is particularly useful for diagnosing pyloric stenosis and intussusception. CT scans may be required for complex cases such as appendicitis or masses. In some cases, nasogastric tube placement can aid in diagnosis and management by assessing gastric contents.


Management begins with initial stabilization, including airway, breathing, and circulation assessment. Fluid resuscitation with isotonic saline (0.9% NS) is essential, especially in dehydrated or hypovolemic children, while cautiously considering conditions such as increased intracranial pressure. Bedside glucose testing is important to detect hypoglycemia. Gastric decompression with a nasogastric or orogastric tube may be required in cases of obstruction or persistent vomiting. Treatment then focuses on identifying and addressing the underlying cause, with early surgical consultation when an acute abdomen is suspected. Antibiotics should be initiated if infection or peritonitis is present.


Antiemetic therapy may be used once serious causes have been excluded or addressed. First-line therapy includes Ondansetron, given at 0.1 mg/kg per dose (typically 4–8 mg) IV or PO every 6 hours. Second-line options include Metoclopramide at 0.1 mg/kg per dose PO every 6 hours, Prochlorperazine at 0.1 mg/kg per dose IV, IM, or PR every 6 hours, and Promethazine at 0.25 mg/kg per dose PO, PR, or IM every 6 hours. These medications should be used cautiously due to potential side effects, especially in younger children.


Disposition depends on the child’s clinical status and underlying cause. Admission is required for unstable vital signs, dehydration, inability to tolerate oral intake, or suspected serious pathology. Children may be discharged if they are stable, able to tolerate fluids, and serious causes have been excluded, with clear instructions given to caregivers regarding warning signs such as persistent vomiting, abdominal distention, decreased urine output, fever, lethargy, or behavioral changes.


A critical clinical pearl is that bilious vomiting in neonates is an emergency and should be assumed to represent intestinal obstruction (e.g., malrotation with volvulus) until proven otherwise. Additionally, clinicians must always consider non-gastrointestinal causes of vomiting, including neurologic, metabolic, and toxicologic etiologies, to avoid missing potentially life-threatening conditions.

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​Emergency and Acute Medicine: Von Willebrand Disease


Von Willebrand Disease is the most common inherited bleeding disorder and results from either a deficiency or dysfunction of von Willebrand factor, a key protein involved in hemostasis. vWF plays two major roles: it mediates platelet adhesion to the vascular endothelium and serves as a carrier protein for Factor VIII. The disease affects approximately 1–2% of the general population and is usually inherited, though acquired forms can occur.


There are three major types of vWD. Type 1, the most common (about 70%), is a quantitative deficiency of vWF and is typically inherited in an autosomal dominant pattern, with symptoms ranging from mild to moderate bleeding. Type 2 involves qualitative defects in vWF function and includes several subtypes (2A, 2B, 2M, 2N), with type 2N characterized by reduced binding to factor VIII, leading to more significant coagulopathy. Type 3 is rare, inherited in an autosomal recessive pattern, and represents a severe deficiency or absence of vWF, resulting in serious bleeding manifestations. In addition to genetic causes, acquired vWD may occur due to conditions such as malignancies, autoimmune diseases, hypothyroidism, or certain medications.


Clinical presentation varies widely depending on the type and severity of the disorder. Many patients with type 1 or mild type 2 disease may be asymptomatic, while those with more severe forms present with mucocutaneous bleeding, including easy bruising, recurrent epistaxis, gum bleeding, and menorrhagia. Gastrointestinal bleeding, prolonged bleeding after procedures, and postoperative hemorrhage may also occur. In more severe cases, such as type 3 disease, patients may develop deep tissue bleeding and hemarthroses, resembling hemophilia. A detailed history often reveals a family history of bleeding and recurrent minor bleeding episodes, especially in pediatric and adolescent populations.


Physical examination is often normal, although findings may include ecchymoses, hematomas, or joint swelling in more severe cases. Special considerations include pregnancy, during which vWF levels may increase temporarily, often leading to fewer bleeding complications; however, levels drop postpartum, increasing the risk of delayed bleeding. In children, clinicians must always consider nonaccidental trauma when unexplained bruising or bleeding is present.


Diagnosis relies on laboratory evaluation. Platelet counts and morphology are typically normal, and prothrombin time (PT) is usually normal. Partial thromboplastin time (PTT) may be mildly prolonged due to reduced factor VIII levels. Specific tests include measurement of vWF antigen and activity, particularly the ristocetin cofactor assay, which evaluates vWF function through platelet agglutination. Bleeding time may be prolonged in more severe types but is less commonly used כיום due to poor reproducibility.


Management focuses on controlling bleeding and correcting the underlying defect. Initial stabilization includes standard resuscitation measures with fluids and blood products as needed, along with direct pressure to bleeding sites. The cornerstone of therapy for mild to moderate disease is Desmopressin, which promotes the release of endogenous vWF and increases factor VIII levels. It is administered at 0.3 μg/kg IV or subcutaneously (maximum 20 μg), or 300 μg intranasally (150 μg if <50 kg), with peak effect occurring within 30–60 minutes and lasting 6–8 hours. It is most effective in type 1 disease, variably effective in type 2, and not useful in type 3.


For severe bleeding or type 3 disease, vWF replacement therapy is required, typically using Humate-P at doses of 20–40 units/kg IV. Antifibrinolytic agents such as Tranexamic acid (20–25 mg/kg PO or IV every 8 hours) and Aminocaproic acid (50–60 mg/kg PO or IV every 4–6 hours) are useful adjuncts, particularly for mucosal bleeding. Although Cryoprecipitate and Fresh frozen plasma may contain vWF, they are generally reserved for life-threatening situations when safer products are unavailable due to infection risk. Patients should avoid antiplatelet medications such as NSAIDs, which can worsen bleeding.


Disposition depends on severity. Patients with significant or ongoing bleeding, especially those requiring IV therapy, should be admitted and managed in consultation with hematology. Those with controlled bleeding and reliable follow-up may be discharged with clear instructions. Long-term management includes hematology referral for definitive diagnosis, planning before surgical procedures, and education regarding bleeding risk.


A key clinical pearl is that patients may not know their specific subtype of bleeding disorder, and in emergency situations with significant bleeding, empiric treatment (e.g., FFP or vWF-containing products) may be necessary while awaiting definitive diagnosis.

Emergency and Acute Medicine: Warfarin Complications




Warfarin is a widely used oral anticoagulant that works by inhibiting vitamin K–dependent clotting factors (II, VII, IX, and X), thereby affecting both the extrinsic and common coagulation pathways. It is commonly prescribed for conditions such as venous thromboembolism, atrial fibrillation, and prosthetic heart valves. Its therapeutic effect is monitored using the International Normalized Ratio, with typical target ranges of 2–3 or 2.5–3.5 depending on indication. However, due to its narrow therapeutic window and numerous interactions, warfarin is associated with significant complications, most notably bleeding.


Bleeding is the most common complication, occurring in up to 15% of patients annually, with major bleeding events in about 5% and fatal bleeding (most often Intracranial hemorrhage) in less than 1%. The risk of bleeding increases significantly when the INR exceeds 4. Patients may present with a wide spectrum of symptoms, ranging from occult bleeding to life-threatening hemorrhage involving the gastrointestinal tract, central nervous system, or retroperitoneum. Conversely, subtherapeutic INR levels may result in breakthrough thrombosis, particularly in high-risk patients.


Several factors predispose patients to unstable INR levels and complications, including advanced age (>75 years), comorbidities such as hypertension, diabetes, renal or liver disease, malignancy, and hyperthyroidism. Drug and dietary interactions are especially important: antibiotics, Amiodarone, NSAIDs, and certain herbal supplements (e.g., ginkgo, garlic) can increase INR, while drugs like Rifampin, carbamazepine, and high vitamin K intake can decrease it. Warfarin is contraindicated in pregnancy due to its teratogenic effects.


A unique complication is warfarin-induced skin necrosis, which typically occurs within the first week of therapy and is associated with protein C deficiency. It presents as painful skin lesions that progress to necrosis with central eschar formation. Limb gangrene may also occur due to venous thrombosis. In cases of overdose or ingestion of long-acting anticoagulants (e.g., “superwarfarins” found in rodenticides), patients may initially be asymptomatic but develop prolonged coagulopathy requiring extended monitoring.


Evaluation requires a thorough history, including indication for anticoagulation, recent dose changes, medication interactions, and prior INR values. Physical examination should focus on signs of bleeding (e.g., ecchymosis, pallor, hypotension) and subtle neurologic changes suggestive of intracranial bleeding. Laboratory testing includes PT/INR, CBC, renal and liver function tests, and type and crossmatch if bleeding is suspected. Imaging, particularly CT scans, should be obtained liberally to detect occult bleeding, especially in trauma patients or those with neurologic symptoms.


Management depends on the INR level and presence of bleeding. For patients with INR <5 and no bleeding, the next dose may be held or reduced with close monitoring. For INR 5–9 without bleeding, holding warfarin and administering Vitamin K1 at 1–5 mg PO may be appropriate, especially in high-risk patients. For INR ≥9 without bleeding, vitamin K 2.5–5 mg PO is recommended. In cases of serious or life-threatening bleeding (any INR), immediate reversal is required with vitamin K 10 mg IV (slow infusion over 10–30 minutes) along with clotting factor replacement.


Rapid reversal is best achieved using Prothrombin complex concentrate, which contains clotting factors II, VII, IX, and X. Dosing is weight- and INR-dependent: 25 U/kg for INR 2–3.9, 35 U/kg for INR 4–5.9, and 50 U/kg for INR ≥6. PCC is preferred in cases of intracranial hemorrhage, massive bleeding, or when volume overload is a concern. Alternatively, Fresh frozen plasma may be used, typically 3–4 units (≈1 L), though it carries risks such as fluid overload and slower INR correction. In refractory or complex cases, adjuncts such as factor VIIa may be considered.


Disposition depends on severity. Patients with active bleeding, especially involving the CNS, GI tract, or retroperitoneum, require admission and often ICU-level care. Stable patients with asymptomatic supratherapeutic INR and reliable follow-up may be discharged with close monitoring. Follow-up within 24–48 hours for repeat INR testing is essential.


A key clinical pearl is to maintain a low threshold for imaging in anticoagulated patients, even after minor trauma, as serious bleeding may occur without obvious symptoms. Additionally, vitamin K should generally not be given for INR <5 without bleeding, and IV vitamin K should be reserved for severe cases due to the rare but serious risk of anaphylaxis.

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Emergency and Acute Medicine: Warts




Warts are benign proliferative lesions of the skin and mucous membranes caused by infection with the Human papillomavirus. The virus infects the basal layer of epithelial tissue, leading to cellular proliferation and increased vascularity, which gives rise to the characteristic verrucous, hyperkeratotic appearance. Warts are extremely common, particularly in children and adolescents, and most resolve spontaneously due to a cell-mediated immune response—about one-third within 6 months, two-thirds within 2 years, and up to 90% within 5 years.


There are several clinical types of warts depending on location and HPV subtype. Verruca vulgaris (common warts) typically occur on the dorsum of the hands, fingers, and around nails and are usually asymptomatic. Verrucae plantaris (plantar warts) occur on weight-bearing areas of the feet such as the heels and metatarsal heads and are often painful due to pressure. Flat (juvenile) warts appear as small, smooth, flesh-colored lesions on sun-exposed areas such as the face, neck, and extremities and may spread with shaving. Anogenital warts, also known as condyloma acuminata, are sexually transmitted and commonly caused by HPV types 6 and 11, while types 16 and 18 are associated with cervical cancer. These lesions are often soft, multiple, and have a cauliflower-like appearance.


Transmission of HPV occurs through direct skin-to-skin contact, indirect contact via contaminated surfaces, or autoinoculation, especially in children who scratch or bite affected areas. The incubation period is variable, ranging from weeks to over a year. In pediatric cases, warts are common, but the presence of anogenital warts should raise concern for possible sexual abuse, particularly in younger children.


Diagnosis is primarily clinical, based on the characteristic appearance of lesions. Common and plantar warts disrupt normal skin lines and may show pinpoint bleeding when scraped. Flat warts are smooth and subtle, while anogenital warts are soft and pedunculated. Laboratory testing is generally unnecessary, although application of acetic acid can help highlight lesions by causing whitening. Biopsy is reserved for atypical, persistent, or suspicious lesions, especially in immunocompromised patients.


Management depends on the type, location, and patient preference. Many warts require no treatment, especially in children, due to high rates of spontaneous resolution. For cutaneous warts, first-line therapy includes topical salicylic acid, typically 17% over-the-counter or up to 70% prescription strength, applied after soaking the wart for 10–20 minutes, left on overnight, and followed by gentle debridement. Treatment is repeated regularly and may take weeks to months. Another simple method is duct tape occlusion therapy, which may be particularly useful in children.


For anogenital warts, treatment options include patient-applied therapies such as Imiquimod (5% cream applied three times per week for up to 16 weeks) and Podofilox (0.5% solution or gel applied twice daily for 3 days followed by 4 days off, repeated up to 4 cycles). Provider-administered treatments include podophyllin (10–25% weekly application), trichloroacetic acid (80–90% weekly for 6–10 weeks), and cryotherapy with liquid nitrogen every 1–2 weeks. These treatments require caution, especially in pregnancy or when applied to sensitive mucosal areas.


Preventive strategies include vaccination with Gardasil, which protects against HPV types 6, 11, 16, and 18 and is given as a 3-dose series over 6 months. This vaccine significantly reduces the risk of genital warts and HPV-related cancers. Another vaccine, Cervarix, targets oncogenic strains associated with cervical cancer.


Most patients can be managed as outpatients, but referral to dermatology or gynecology is appropriate for treatment-resistant cases, atypical lesions, or anogenital involvement. Follow-up is important to ensure treatment response and monitor for recurrence. Patients should be advised to return if lesions change, become painful, or fail to improve.


A key clinical pearl is that HPV vaccines do not protect against all HPV types, and patients may still develop warts despite vaccination. Additionally, clinicians should always consider the broader clinical context, including the possibility of immunosuppression or, in pediatric cases with anogenital lesions, safeguarding concerns.

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Emergency and Acute Medicine – West Nile Virus




West Nile Virus is a mosquito-borne viral illness caused by an RNA virus from the Flaviviridae family. It is transmitted primarily by infected Culex mosquito during late summer and early fall. Wild birds serve as the main reservoir, and humans become incidental hosts through mosquito bites. Less commonly, transmission can occur via blood transfusion, organ transplantation, or occupational exposure. Since its introduction to the Western Hemisphere in 1999, the virus has become endemic in many regions. After recovery, immunity is generally lifelong, and recurrence is rare.


The clinical presentation of West Nile virus infection varies widely. Approximately 80% of infected individuals are asymptomatic, while about 20% develop a mild, self-limited febrile illness resembling a viral syndrome. A small proportion—roughly 1 in 150 patients—develops neuroinvasive disease, such as meningitis or encephalitis. The incubation period is typically 2–6 days but may extend up to 2–3 weeks, especially in immunocompromised individuals. Severe disease carries a mortality rate of around 7%, with higher risk in elderly patients and those with weakened immune systems.


Patients with mild disease usually present with fever, malaise, headache, anorexia, and sometimes gastrointestinal symptoms such as nausea or diarrhea. These symptoms typically resolve within a week, although fatigue and weakness may persist for several weeks. In more severe cases, neurologic involvement dominates the clinical picture. Patients may develop altered mental status, confusion, seizures, or focal neurologic deficits. A characteristic feature is profound muscle weakness or flaccid paralysis, which can resemble poliomyelitis due to involvement of anterior horn cells. Cranial nerve abnormalities, bulbar dysfunction, and movement disorders may also occur. A transient maculopapular rash may appear on the trunk and extremities.


Diagnosis relies primarily on serologic testing, with the most sensitive method being detection of IgM antibodies using MAC-ELISA in serum or cerebrospinal fluid (CSF). IgM antibodies are usually detectable within the first week of illness and may persist for months. CSF analysis in neuroinvasive disease typically shows lymphocytic pleocytosis, elevated protein, and normal glucose. Imaging such as CT is often normal, while MRI may reveal nonspecific signs of central nervous system inflammation.


Management of West Nile virus is primarily supportive, as there is currently no specific antiviral therapy or vaccine available. Initial stabilization includes airway, breathing, and circulation support, along with seizure precautions if indicated. Treatment consists of intravenous fluids for dehydration, antipyretics for fever, and analgesics for pain. In patients presenting with suspected meningitis or encephalitis, empiric antibiotics and Acyclovir may be initiated until other treatable causes, particularly herpes simplex virus infection, are excluded. No medications—including interferon, ribavirin, or corticosteroids—have proven benefit in controlled studies.


Disposition depends on disease severity. Patients with neurologic involvement, dehydration, advanced age, or immunocompromise require hospital admission, often with neurologic monitoring. Those with mild illness who can tolerate oral intake and have no signs of central nervous system involvement may be discharged with close follow-up. Long-term sequelae such as fatigue, memory impairment, weakness, and headache may persist for weeks to months, and follow-up with a neurologist is often recommended in severe cases.


A key clinical pearl is to always consider other causes of encephalitis, particularly herpes simplex virus, since it is treatable and requires early intervention.

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Emergency and Acute Medicine: Ventriculoperitoneal Shunts




Ventriculoperitoneal shunt (VP shunt) is a device used to treat Hydrocephalus by diverting cerebrospinal fluid (CSF) from the ventricles of the brain to the peritoneal cavity, where it can be absorbed. The system typically consists of a ventricular catheter, a valve mechanism, and distal tubing. Although life-saving, VP shunts are associated with significant complication rates, especially within the first year after placement.


The most common complication is shunt malfunction due to obstruction, which impairs CSF drainage and leads to increased intracranial pressure (ICP). The severity of symptoms depends on how rapidly ICP rises. Patients may present with headache, nausea, vomiting, irritability, and decreased level of consciousness. In children, especially infants with open fontanelles, symptoms may be more subtle and include drowsiness, feeding difficulties, or increasing head circumference. Neurologic signs such as seizures, decreased upward gaze, and autonomic instability may also occur.


Another important complication is overdrainage syndrome, in which excessive CSF outflow leads to low intracranial pressure. This typically causes postural headaches that worsen when the patient is upright and improve when lying down, often accompanied by nausea. In severe cases, rapid overdrainage can result in brainstem displacement and signs of herniation, including apnea, bradycardia, and decreased consciousness.


Shunt infection is a serious and potentially life-threatening complication because the device acts as a foreign body. The most common organisms are Staphylococcus species, particularly Staphylococcus epidermidis, although gram-negative organisms and resistant strains such as MRSA may also be involved. Infections usually occur within the first six months after placement. Clinical features include fever, meningeal signs, altered mental status, and local signs such as redness, swelling, or tenderness along the shunt tract. Peritonitis may also occur if infection spreads distally.


A less common but important complication is slit ventricle syndrome, which occurs after prolonged overdrainage. The ventricles become chronically small, and patients develop intermittent symptoms of increased ICP due to episodic obstruction. These patients often have recurrent headaches with alternating periods of normal and altered mental status.


Evaluation of a suspected VP shunt complication begins with a careful history, including the timing of shunt placement and any recent revisions or manipulations. Physical examination should assess mental status, focal neurologic deficits, and signs of infection along the shunt tract. In suspected malfunction, bedside assessment of the shunt reservoir may be attempted; failure to compress or refill appropriately may suggest obstruction, although this test is not fully reliable.


Imaging plays a central role in diagnosis. A noncontrast CT scan of the head is used to assess ventricular size and catheter position, with enlargement suggesting obstruction and small ventricles suggesting overdrainage. A shunt series, consisting of radiographs of the skull, chest, and abdomen, helps identify disconnection, kinking, or malposition of the tubing. In children with open fontanelles, ultrasound may be used to evaluate ventricular size. If infection is suspected, cerebrospinal fluid may be obtained from the shunt reservoir for analysis and culture, typically in consultation with a neurosurgeon.


Management depends on the underlying complication but always begins with stabilization. Patients with signs of increased ICP or impending herniation require urgent airway management and measures to reduce ICP, such as head elevation, controlled ventilation, and administration of osmotic agents like mannitol. In some cases, careful manipulation or tapping of the shunt may temporarily relieve pressure, but this should be done cautiously and ideally with specialist input.


Definitive management requires early neurosurgical consultation. Shunt malfunction often necessitates surgical revision, while infections typically require removal of the shunt and initiation of broad-spectrum intravenous antibiotics, such as vancomycin combined with a third-generation cephalosporin or an aminoglycoside. Overdrainage is managed by placing the patient in a supine position and correcting volume depletion.


Most patients with suspected VP shunt complications require hospital admission, often to a monitored or intensive care setting. Prompt recognition and management are essential to prevent serious complications such as permanent neurologic damage or death. Importantly, clinicians should avoid attributing all symptoms to the shunt and must consider alternative diagnoses, as conditions such as metabolic disturbances or infections can mimic shunt malfunction.

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Emergency and Acute Medicine: Vertigo




Vertigo is a specific type of dizziness characterized by the false sensation of movement—typically spinning—either of the patient or the surrounding environment. It accounts for a significant proportion of emergency department visits and can arise from dysfunction in any of the three systems responsible for balance: the visual, proprioceptive, and vestibular systems. Clinically, vertigo must be distinguished from other nonspecific dizziness symptoms such as lightheadedness or presyncope, as it more often reflects an underlying neurologic or vestibular disorder.


Vertigo is broadly classified into peripheral and central causes. Peripheral vertigo, which originates from the inner ear or vestibular nerve, tends to produce severe, episodic symptoms lasting seconds to minutes, often triggered by head movement. It is commonly associated with horizontal or torsional nystagmus that fatigues and improves with visual fixation. Common causes include Benign Paroxysmal Positional Vertigo, the most frequent etiology due to displaced otoliths in semicircular canals; Vestibular Neuritis, which presents as continuous vertigo without hearing loss; and Ménière Disease, characterized by episodic vertigo, hearing loss, and tinnitus. In contrast, central vertigo arises from pathology in the brainstem or cerebellum, such as Vertebrobasilar Insufficiency, stroke, multiple sclerosis, or tumors. Central causes often present with milder but continuous vertigo, non-fatigable or vertical nystagmus, and associated neurologic deficits.


The history is crucial in distinguishing etiologies. Sudden, brief episodes triggered by head movement strongly suggest BPPV, whereas continuous vertigo lasting days suggests vestibular neuritis. Recurrent episodes with auditory symptoms point toward Ménière disease. Red flags for central causes include neurologic symptoms such as diplopia, dysarthria, limb weakness, ataxia, or severe imbalance out of proportion to vertigo. Stroke risk factors, including older age and vascular disease, further increase suspicion for a central cause.


Physical examination focuses on eye movements and neurologic assessment. Evaluation of nystagmus provides key diagnostic clues: unidirectional horizontal nystagmus suggests peripheral vertigo, whereas vertical, bidirectional, or non-fatigable nystagmus suggests central pathology. The head impulse test helps identify vestibular dysfunction, while skew deviation testing can indicate central lesions. The Dix–Hallpike maneuver is used to diagnose posterior canal BPPV, and the supine roll test assesses lateral canal involvement. A full neurologic exam is essential to identify subtle deficits suggestive of central causes.


Management depends on the underlying etiology. Peripheral vertigo is typically treated symptomatically with antihistamines (e.g., meclizine), benzodiazepines, and antiemetics. Repositioning maneuvers such as the Epley or Semont maneuvers are highly effective for BPPV. In contrast, central vertigo requires urgent evaluation and management of the underlying cause, such as stroke or hemorrhage, often involving neuroimaging and specialist consultation. Admission is indicated for serious causes like cerebellar infarction, vertebrobasilar insufficiency, or intractable symptoms preventing ambulation or oral intake.


A key clinical pearl is that vertigo can be the sole presenting symptom of a posterior circulation stroke. Therefore, clinicians must maintain a high index of suspicion, especially when vertigo is accompanied by neurologic signs or occurs in patients with vascular risk factors.

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