Humans

Measles is a highly contagious virus with a primary case reproduction number (i.e., the average number of secondary cases per case patient) of 12 to 18. It is currently spreading rapidly owing to reduced measles vaccination coverage, which is due primarily to the disruption of local immunization programs by the coronavirus disease 2019 (Covid-19) pandemic and of growing vaccine hesitancy.1 Since 2024, all World Health Organization (WHO) regions have reported increased numbers of measles cases, with 395,521 laboratory-confirmed measles cases reported in 2024 and 16,147 reported during the first 2 months of 2025.2 Patients in more than half the reported cases were hospitalized, so the true number is probably much higher.3
This review covers clinical presentations and complications of measles, current recommendations, and the epidemiologic background of measles. It also addresses the current debates on immunization and the treatment of measles and presents information on the origins of the various measles vaccines and updates on measles diagnostic testing and molecular genotypes.

Importance: Approximately 27% of adults in the US and Canada report having ever used cannabis for medical purposes. An estimated 10.5% of the US population reports using cannabidiol (CBD), a chemical compound extracted from cannabis that does not have psychoactive effects, for therapeutic purposes.

Observations: Conditions for which cannabinoids have approval from the US Food and Drug Administration include HIV/AIDS-related anorexia, chemotherapy-induced nausea and vomiting, and certain pediatric seizure disorders. A meta-analysis of randomized clinical trials reported a small but significant reduction in nausea and vomiting from various causes (eg, chemotherapy, cancer) when comparing prescribed cannabinoids (eg, dronabinol, nabilone) with placebo or active comparators (eg, alizapride, chlorpromazine; standardized mean difference [SMD], -0.29 [95% CI, -0.39 to -0.18]). A meta-analysis of randomized clinical trials among patients with HIV/AIDS reported that cannabinoids had a moderate effect on increasing body weight compared with placebo (SMD, 0.57 [95% CI, 0.22 to 0.92]). Evidence-based guidelines do not recommend the use of inhaled or high-potency cannabis (≥10% or 10 mg Δ9-tetrahydrocannabinol [Δ9-THC]) for medical purposes. High-potency cannabis compared with low-potency cannabis use is associated with increased risk of psychotic symptoms (12.4% vs 7.1%) and generalized anxiety disorder (19.1% vs 11.6%). A meta-analysis of observational studies reported that 29% of individuals who used cannabis for medical purposes met criteria for cannabis use disorder. Daily inhaled cannabis use compared with nondaily use was associated with an increased risk of coronary heart disease (2.0% vs 0.9%), myocardial infarction (1.7% vs 1.3%), and stroke (2.6% vs 1.0%). Evidence from randomized clinical trials does not support the use of cannabis or cannabinoids for most conditions for which it is promoted, such as acute pain and insomnia. Before considering cannabis or cannabinoids for medical use, clinicians should consult applicable institutional, state, and national regulations; evaluate for drug-drug interactions; and assess for contraindications (eg, pregnancy) or conditions in which risks likely outweigh benefits (eg, schizophrenia or ischemic heart disease). For patients using cannabis or cannabinoids for treatment of medical conditions, clinicians should discuss harm reduction strategies, including avoiding concurrent use with alcohol or other central nervous system depressants such as benzodiazepines, using the lowest effective dose, and avoiding use when driving or operating machinery.

Conclusions and relevance: Evidence is insufficient for the use of cannabis or cannabinoids for most medical indications. Clear guidance from clinicians is essential to support safe, evidence-based decision-making. Clinicians should weigh benefits against risks when engaging patients in informed discussions about cannabis or cannabinoid use.

Importance: Lung cancer in nonsmoking individuals (defined as people who have smoked fewer than 100 cigarettes in their lifetime) accounts for 15% to 20% of all lung cancer cases worldwide. In the US, the annual incidence of lung cancer in nonsmoking individuals is 14.4 to 20.8 per 100 000 person-years in females and 4.8 to 12.7 per 100 000 person-years in males.

Observations: Most lung cancers in nonsmoking individuals are histologically adenocarcinomas (60%-80%) with the remainder being squamous or adenosquamous (10%-20%) and rarely small cell lung cancer (<10%). Risk factors include exposure to passive smoking, radon exposure, air pollution, asbestos, and history of lung cancer in a first-degree family member. Therapeutically targetable genomic variants, such as EGFR mutations or ALK gene rearrangements, are more common in tumors from nonsmoking individuals compared with those with a smoking history (defined as people who currently or formerly smoked) (43% vs 11% for EGFR and 12% vs 2% for ALK). In contrast, tumor mutation burden, the number of somatic mutations in a tumor cell, is lower in lung cancer among nonsmoking individuals (0-3 mutations/megabase [Mb] vs 0-30 mutations/Mb). Similar to individuals with a history of smoking, nonsmoking individuals with lung cancer may present with wheeze, chest pain, dyspnea, hemoptysis, or symptoms attributable to metastatic disease (eg, bone pain and headache) or be diagnosed with incidentally detected disease. The US Preventive Services Task Force does not currently recommend lung cancer screening with low-dose computed tomographic scans for nonsmoking individuals, although screening guidelines vary globally. Treatment typically involves a combination of surgery, radiotherapy, and systemic therapies depending on stage, performance status, and molecular features of the tumor. Comprehensive next-generation sequencing should be performed on stage Ib to IIIa lung cancer tumor tissue from nonsmoking individuals because actionable genomic alterations, such as EGFR mutations or ALK gene rearrangements, are treated with targeted therapy such as the tyrosine kinase inhibitors osimertinib or lorlatinib, respectively. Median survival among nonsmoking individuals with advanced non-small cell lung cancer (stage IIIb or higher) and actionable genomic alterations can exceed 3 to 5 years, while survival without these genomic alterations is similar to lung cancer in people with a history of smoking (1-2 years).

Conclusions: Lung cancer in nonsmoking individuals accounts for 15% to 20% of lung cancer cases worldwide. Among patients with lung cancer, nonsmoking individuals are more likely to have genomic alterations such as EGFR mutations or ALK gene rearrangements, and these patients have improved survival when treated with tyrosine kinase inhibitors compared with chemotherapy.

Importance Metabolic dysfunction–associated steatotic liver disease (MASLD) includes a range of liver conditions, progressing from isolated steatosis (characterized by fat accumulation in the liver without inflammation) to metabolic dysfunction–associated steatohepatitis (MASH), which involves fat accumulation and inflammation in the liver. The presence of MASLD is associated with increased morbidity and mortality due to liver-related complications, hepatocellular carcinoma, cardiovascular disease, and certain extrahepatic cancers.

Observations The most common chronic liver disease worldwide, MASLD affects approximately 30% to 40% of the general adult population globally (with varying prevalence across continents), including approximately 60% to 70% of individuals with type 2 diabetes and approximately 70% to 80% of those with obesity. It is typically diagnosed based on an ultrasonographic finding of hepatic steatosis, along with at least 1 of 5 features of the metabolic syndrome (abdominal overweight or obesity, prediabetes or type 2 diabetes, hypertension, elevated level of plasma triglycerides, and low level of high-density lipoprotein cholesterol) for women who consume less than 140 g/wk of alcohol (<2 standard drinks/d) and for men who consume less than 210 g/wk (<3 standard drinks/d) and have no other known causes of steatosis such as use of a particular medication (eg, corticosteroids, tamoxifen, or methotrexate), hepatitis C, or iron overload. Other risk factors for MASLD include older age (≥50 years) and male sex (male:female ratio approximately 2). The Fibrosis-4 index (a scoring system incorporating age, serum levels of aspartate aminotransferase and alanine aminotransferase, and platelet count) and vibration-controlled transient elastography (a noninvasive imaging technique) are commonly used to stage hepatic fibrosis in patients with MASLD. Cardiovascular disease is the leading cause of death, followed by certain extrahepatic cancers (primarily gastrointestinal, breast, and gynecologic cancer) and liver-related complications, including cirrhosis, hepatic decompensation (ascites, hepatic encephalopathy, or variceal bleeding), and hepatocellular carcinoma. First-line treatment of MASLD involves behavioral modifications (including hypocaloric low-carbohydrate and low-fat diets, physical exercise, and avoidance of alcohol) and management of type 2 diabetes, obesity, hypertension, and hyperlipidemia. Bariatric surgery should be considered for patients with MASLD and a body mass index greater than 35. Resmetirom (a liver-directed, thyroid hormone receptor β-selective agonist) and subcutaneous semaglutide (a glucagon-like peptide-1 receptor agonist) are conditionally approved by the US Food and Drug Administration (FDA) for the treatment of adults with MASH who have moderate to advanced fibrosis.

Conclusions A highly prevalent condition among adults worldwide, MASLD is associated with liver-related complications, hepatocellular carcinoma, cardiovascular disease, and certain extrahepatic cancers. First-line treatment includes behavioral modifications, including a weight-reducing diet, physical exercise, and avoidance of alcohol. Resmetirom and semaglutide are conditionally FDA-approved medications for the treatment of adults with MASH and moderate to advanced fibrosis.