Humans

»Neutropenia is seen in 5%–10% of healthy people
Based on absolute neutrophil count, neutropenia is commonly defined as
mild (1.0–1.5 × 109
/L), moderate (0.5–0.9 × 109
/L) or severe (< 0.5 × 109
/L).1
However, the reference interval is specific to the population. Mild asymptomatic neutropenia per the above definition is common in people of subSaharan African, Arab or West Indian ancestry,2
and is strongly associated
with the Duffy-null phenotype of red blood cells that protects against
Plasmodium vivax malaria.
2 Common causes include medications, infection, nutritional
deficiency, malignant disease and autoimmune disease
Causes include underproduction (e.g., myelodysplastic syndrome),
immune-mediated destruction or redistribution of neutrophils to the
endothelium and reticuloendothelial system. Antithyroid, anti-infective
and psychotropic drugs, as well as chemotherapy, are causes of druginduced neutropenia.3,4 Transient neutropenia may occur after acute
viral infection and typically resolves within 2 weeks. Joint swelling, rash,
bony pain, splenomegaly or lymphadenopathy may suggest malignant or
autoimmune disease.
3Investigation should begin with a repeat complete blood count
and peripheral blood film
Neutropenia is often identified incidentally. Persistent and unexplained
neutropenia requires further work-up for a range of causes, including
chronic viral infection (e.g., hepatitis, HIV) and nutritional deficiency (e.g.,
vitamin B12) (Appendix 1, available at www.cmaj.ca/lookup/doi/10.1503/
cmaj.220499/tab-related-content).
4 Treatment of mild neutropenia should be directed at the
underlying cause
Patients with mild neutropenia are not at substantially increased risk of
infection.5
The neutrophil count should be checked every 3–6 months for
at least 1 year to rule out progression to more severe neutropenia.
5 Patients with moderate-to-severe neutropenia for more than
6 months should be referred to a specialist
Patients with recurrent or severe bacterial infections (e.g., requiring hospital admission or intravenous antibiotics), abnormalities on peripheral blood
films (e.g., circulating blasts, hairy cells, large granular lymphocytes, dysplastic granulocytes) or pancytopenia also warrant referral to a specialist
(e.g., hematologist, internist, pediatrician).1
Febrile neutropenia (absolute
neutrophil count < 0.5 × 109
/L and an oral temperature > 38.0°C sustained
over 1 h) requires immediate treatment with broad-spectrum antibiotics.

Importance: Syphilis is a sexually transmitted infection that can progress through different stages (primary, secondary, latent, and tertiary) and cause serious health problems if left untreated. Reported cases of primary and secondary syphilis in the US increased from a record low of 2.1 cases per 100 000 population in 2000 and 2001 to 11.9 cases per 100 000 population in 2019. Men account for the majority of cases (83% of primary and secondary syphilis cases in 2019), and rates among women nearly tripled from 2015 to 2019.

Objective: To reaffirm its 2016 recommendation, the US Preventive Services Task Force (USPSTF) commissioned a reaffirmation evidence update focusing on targeted key questions evaluating the performance of risk assessment tools and the benefits and harms of screening for syphilis in nonpregnant adolescents and adults.

Population: Asymptomatic, nonpregnant adolescents and adults who have ever been sexually active and are at increased risk for syphilis infection.

Evidence assessment: Using a reaffirmation process, the USPSTF concludes with high certainty that there is a substantial net benefit of screening for syphilis infection in nonpregnant persons who are at increased risk for infection.

Recommendation: The USPSTF recommends screening for syphilis infection in persons who are at increased risk for infection. (A recommendation).

Monkeypox is a viral infection with person-to-person
transmission through direct contact or fomites
The virus is endemic to West and Central Africa.1
Animal-to-human transmission may initiate outbreaks, and person-to-person transmission
occurs through direct, close contact with a person during their infectious
stage through droplets, contact with infectious bodily fluids or via fomites
(e.g., linens). Airborne transmission is thought to be less common.

Background: Contemporary data are needed about the utility of cannabinoids in chronic pain.

Purpose: To evaluate the benefits and harms of cannabinoids for chronic pain.

Data sources: Ovid MEDLINE, PsycINFO, EMBASE, the Cochrane Library, and Scopus to January 2022.

Study selection: English-language, randomized, placebo-controlled trials and cohort studies (≥1 month duration) of cannabinoids for chronic pain.

Data extraction: Data abstraction, risk of bias, and strength of evidence assessments were dually reviewed. Cannabinoids were categorized by THC-to-CBD ratio (high, comparable, or low) and source (synthetic, extract or purified, or whole plant).

Data synthesis: Eighteen randomized, placebo-controlled trials (n = 1740) and 7 cohort studies (n = 13 095) assessed cannabinoids. Studies were primarily short term (1 to 6 months); 56% enrolled patients with neuropathic pain, with 3% to 89% female patients. Synthetic products with high THC-to-CBD ratios (>98% THC) may be associated with moderate improvement in pain severity and response (≥30% improvement) and an increased risk for sedation and are probably associated with a large increased risk for dizziness. Extracted products with high THC-to-CBD ratios (range, 3:1 to 47:1) may be associated with large increased risk for study withdrawal due to adverse events and dizziness. Sublingual spray with comparable THC-to-CBD ratio (1.1:1) probably is associated with small improvement in pain severity and overall function and may be associated with large increased risk for dizziness and sedation and moderate increased risk for nausea. Evidence for other products and outcomes, including longer-term harms, were not reported or were insufficient.

Limitation: Variation in interventions; lack of study details, including unclear availability in the United States; and inadequate evidence for some products.

Conclusion: Oral, synthetic cannabis products with high THC-to-CBD ratios and sublingual, extracted cannabis products with comparable THC-to-CBD ratios may be associated with short-term improvements in chronic pain and increased risk for dizziness and sedation. Studies are needed on long-term outcomes and further evaluation of product formulation effects.