Erica Weir

Deprescribing for older patients

The principles that guide optimal prescribing for older patients[1][1],[2][2] ([Box 1][3]) include deprescribing medications that are no longer indicated, appropriate or aligned with evolving goals of care. Deprescribing is a relatively new term that focuses attention on the sometimes overlooked

Protecting against Clostridium difficile illness

Background and epidemiology: A gram-positive, anaerobic bacterium that is common in the environment, Clostridium difficile is transmitted by the fecal– oral route. Its resistant spores are ingested, survive passage through the stomach and ultimately reside in the colon.[1][1] Antimicrobial therapy

Lymphogranuloma venereum in the differential diagnosis of proctitis

Background and epidemiology : Lymphogranuloma venereum (LGV) is a systemic STD caused by infection by Chlamydia trachomatis serotypes L1, L2 and L3, which are endemic in parts of Africa, Asia, South America and the Caribbean but rare in Western countries. Unlike the more common C. trachomatis

Hand–arm vibration syndrome

![Figure][1] Figure. Photo by: Art Explosion Background and epidemiology: Hand–arm vibration syndrome (HAVS) refers to a constellation of vascular, neurological and musculoskeletal signs and symptoms that may occur in workers who use handheld vibrating tools, in particular drills,

Enhanced surveillance for Salmonella Newport

Background and epidemiology: Between Apr. 1 and Dec. 31, 2004, Health Canada, in collaboration with provincial and territorial governments, is undertaking enhanced surveillance for Salmonella enterica serotype Newport. Physicians are urged to collect stool specimens for suspected cases of

Mass sociogenic illness

Background and epidemiology: Mass sociogenic illness refers to the “rapid spread of illness signs and symptoms affecting members of a cohesive group, originating from a nervous system disturbance involving excitation, loss or alteration of function, whereby physical complaints that are exhibited

Uranium in drinking water, naturally

Background: Uranium is a naturally occurring radionuclide in granite and other mineral deposits. It enters local water, air and food supplies in varying concentrations through leaching from natural deposits, its release in mill tailings, emissions from nuclear industry, dissolution in phosphate

Yellow fever: readily prevented but difficult to treat

Background and epidemiology: Yellow fever is a viral hemmorhagic fever endemic in jungle areas and, less commonly, urban areas of South America and Africa. It is caused by a flavivirus that is passed to humans inadvertently through the bite of the Aedes aegypti mosquitoes (urban cycle) or of Haemagogus or other forest-canopy species of mosquitoes (jungle or forest cycle). Endemicity is maintained by the presence of the vector (mosquitoes) and nonhuman primates (monkeys) as the zoonotic focus.1 According to estimates by the World Health Organization (WHO) in 1998, each year about 200 000 people become ill with yellow fever worldwide, but the true incidence is likely much higher. About 90% of cases occur in Africa and 10% in South America. In South America this disease manifests primarily in nonhuman primates, with the peak transmission between January and March, particularly in areas cleared of trees for habitation and agriculture. South America has been epidemic-free since 1942 because of a successful A. aegypti eradication program, but the threat of resurgence remains. In Africa, transmission occurs in the tropical rain forest, moist savannah and contiguous dry savannah areas. Peak transmission occurs in the rainy season and early dry season from July through October. Between 1979 and 2002 there were 10 reported cases of imported yellow fever in returning travellers, reflecting increasing global travel to endemic areas.2 The incubation period for yellow fever is generally 3–6 days. Classic illness passes through 3 defined phases: infection, remission and intoxication. Not all cases progress through the 3 phases. Mild illness characterized by fever, prostration, headache, myalgia, abdominal pain and vomiting may resolve immediately and permanently following the period of infection. More severe cases may progress through a period of remission, marked by a sudden fall in fever lasting several hours or days, to intoxication. The period of intoxication presents with jaundice, azotemia, oliguria, myocardial, renal and hepatic involvement, encephalopathy and hemorrhage, characterized by hematemesis. People with yellow fever have a 10% mortality rate; this rate may climb as high as 50% in cases of hemorrhagic fever. People of all ages are equally susceptible, but in epidemics those who are too young to have been immunized during previous epidemics are more vulnerable. A large proportion of cases worldwide are in men aged 15–45, reflecting occupational exposure through forestry or agricultural work in mosquito-ridden jungle areas. Unlike other hemorrhagic fevers, yellow fever is not directly transmitted from person to person. Impoverished areas with poor health care, limited access to immunization and limited resources for reducing exposure to mosquitoes have the highest rates of cases. Clinical management: Three questions on patient history that could suggest yellow fever are outlined in Table 1.3 Signs during the infection phase include fever, Fagets sign (bradycardia in relation to fever), conjuctival injection, facial flushing, coated tongue with pink edges and leukopenia. Abrupt resolution of fever and other signs may indicate the period of remission. Signs of intoxication include icterus, hemorrhage (e.g., epistaxis, hematemesis, melena, metrorrhagia), albuminuria (day 3 or 4), azotemia, shock and encephalopathy. Encephalopathy is not uncommon, with patients usually dying within 7–10 days of onset. Table 1 A number of laboratory tests can be supportive in making the diagnosis of yellow fever (Table 2). Serologic testing can definitively diagnose yellow fever in a single sample by early testing for immunoglobulin M by an enzyme-linked immunosorbent assay (ELISA) or in paired acute and convalescent sera samples. The ELISA method is preferred because of its sensitivity and relative specificity, but neutralization tests provide the highest specificity. Table 2 Liver biopsies show a characteristic but not diagnostic midzone necrosis with sparing of hepatocytes around the central vein and portal triad. Viral antigen has been found in degenerating hepatocytes and Councilman bodies. Treatment is supportive; it should involve intensive care in severe cases and consultation with infectious disease specialists. Prevention: Yellow fever is readily prevented by vaccinating residents of and travellers to endemic zones. The yellow fever vaccine is a live attenuated strain of the yellow fever virus (17D) developed by Theiler and Smith in 1927. The WHO currently approves only 5 manufacturers of the yellow fever vaccine. Countries located in yellow fever endemic areas may officially require proof of yellow fever vaccination as a condition of entry under WHO international health regulations. There are also countries outside of the endemic areas that may require proof of vaccination because such yellow fever-free countries have the appropriate climatic and entomologic conditions to initiate and maintain a yellow fever transmission cycle. Travellers are asked to consult travel medicine specialists for specific requirements. The vaccine is approved for children older than 9 months, but because it is an attenuated live vaccine it is contraindicated in pregnancy though safe for breastfeeding mothers. It is generally contraindicated in immunocompromised people, though individual risk assessments are necessary for such cases. Waivers approved by the WHO can be provided to travellers with contraindications for the vaccine by certified travel medicine centres. Such patients should be counselled on prevention methods. The yellow fever vaccine has a long record of safety, but clinicians should be aware of 2 severe complications from the vaccine. Yellow fever-associated neurotropic disease (previously known as postvaccine encephalitis), most common in infants, occurs 7–21 days after vaccination. Of the 1/8 000 000 people who contract this disease, full recovery is typical. Yellow fever-associated viscerotropic disease occurs 2–5 days after vaccination. It is characterized by fever, myalgia, arthralgia, increased liver enzymes and bilirubin, lymphopenia, thrombocytopenia, disseminated intravascular coagulation, hypotension, oliguria and rhabdomyolysis. There have been 13 cases reported out of over 100 million doses administered worldwide.4 The vaccine should be given no less then 10 days before departure, and revaccination should occur every 10 years. The vaccine should only be administered by certified vaccine centres knowledgeable in travel medicine and vaccine reaction management, particularly if concurrent administration of other vaccines is indicated, because these may need to be staggered. People with an allergy to egg proteins or gelatin should not be given the yellow fever vaccine.4 Erica Weir Associate Medical Officer of Health Kingston, Frontenac and Lennox & Addington Health Unit Kingston, Ont. Shariq Haider Division of Infectious Diseases McMaster University Medical Centre Hamilton, Ont.

Avian influenza outbreak: update

Background and epidemiology: Emergency preparedness means preparing for the worst while hoping for the best and learning from the past while anticipating the future. In 1999 the World Health Organization (WHO) issued an influenza pandemic preparedness plan[1][1] to guide public health officials in

Raw milk and the protection of public health

The raw-food movement, characterized by eating raw rather than cooked food, is a fledgling but growing trend in North America. One product that might be incorporated and distributed under this movement is raw, or unpasteurized, milk. Physicians, members of the public and public health officials need to be alert to the fact that raw milk is a hazardous product. Raw milk is a known vehicle and medium for pathogens such as Escherichia coli, Mycobacterium bovis, Listeria monocytogenes and species of Campylobacter, Brucella and Salmonella. From 1988 to 2005, a total of 33 outbreaks of campylobacter, salmonella and E. coli O157:H7 infections associated with raw-milk consumption were reported to the US Centers for Disease Control and Prevention. The most recently reported outbreak involved 18 cases with a mean age of 9 years. Of the cases, 4 were admitted to hospital with hemolytic uremic syndrome. In England and Wales, from 1992 to 2000, 14 outbreaks of infectious intestinal diseases that were associated with rawmilk consumption were reported to the UK Communicable Disease Surveillance Centre. In Canada, there were 4 reported cases in 2005 of illness due to E. coli O157:H7 infections that were associated with raw-milk consumption in Ontario. Milk can become contaminated in many ways. For example, if a dairy cow has a mammary gland infection (mastitis) or a systemic infection, the pathogen can be passed to the milk. Milk can also become contaminated by manure dust or by equipment used for milk collection or storage. A number of hygienic practices, such as vigilant and routine equipment cleaning and attention to proper storage and handling of milk, can reduce the risk of contamination. Pasteurization, which in Ontario involves heating and maintaining the temperature of the milk to 72°C for 16 seconds, greatly reduces the bacterial load in collected milk. Provided that the pasteurized milk is adequately stored and refrigerated and is consumed before the established “best-before” date, the risk of infection from consuming pasteurized milk is very low. In developed countries, most jurisdictions have enacted legislation to ensure the safety of milk products. In Canada, the sale of raw milk has been strictly prohibited since 1991 under the federal Food and Drug Regulations. These regulations require that all milk for sale in Canada be pasteurized. Provinces may pass laws with respect to the prohibition of unpasteurized milk within their sphere of jurisdiction, provided that their laws do not conflict with federal legislation. The move to require milk pasteurization in Ontario was spearheaded in the 1890s by Adelaide Hoodless, following the death of her young son after he acquired an infection from raw milk. Through her efforts, the Women’s Institute was founded, which later influenced the introduction of milk pasteurization in the 1930s in the Public Health Act. In 1965, the Milk Act came into force. The Milk Act regulates the quality of milk products sold in Ontario and requires that all distributors and operators of premises where milk products are processed be licensed (Box 1). The Ontario Ministry of Agriculture and Food and Rural Affairs (OMAFRA) is responsible for enforcement of the Milk Act. Currently, the investigations and prosecutions of OMAFRA are carried out by the investigative arm of the Ontario Ministry of Natural Resources. In 1983, the Health Protection and Promotion Act came into force and replaced the Public Health Act. The act sets out a mandate for boards of health with respect to the provision of public health services, and it sets out the powers and duties of the chief medical officer and the medical officers of health in Ontario, among other things. Several sections of the act provide investigative and enforcement powers that enable medical officers of health and their delegates to investigate and prevent the distribution of raw milk and raw-milk products. An exception to the Health Protection and Promotion Act was created by the Ontario Food Premises Regulations for cheese made from unpasteurized milk. The sale of this product is not prohibited if it has been stored below 2°C for at least 60 days following manufacturing. The following hypothetical case illustrates how the public health system of Ontario would respond to a case of raw-milk exposure.