Infectious Diseases

Access to effective TB treatment a human right

A report from the World Health Organization and the International Union against TB and Lung disease indicates that resistance to at least 1 TB drug has increased by 50% in both Denmark and Germany and doubled in New Zealand. Multidrug-resistant strains of tuberculosis have already cost cities like New York and countries such as Russia hundreds of lives and more than $1 billion each, and these strains will continue to emerge unless countries act quickly to strengthen their control over the disease, WHO said. CMAJ 2000;162(10):1470-1.

AIDS orphans

Worldwide, an estimated 8.2 million children have been orphaned by AIDS, and that figure is slated to escalate to 40 million people — roughly 10 million more than Canada’s current population — within a decade. In some regions of Africa, 30% to 40% of women are infected, as are 20% of babies. CMAJ 2000;162(5):683.

DNA amplification and infectious diseases

In the past decade molecular techniques to amplify and detect minute amounts of nucleic acid sequences from tissues and body fluids have been developed. The most widely used and well known of these is the polymerase chain reaction (PCR), which involves denaturing, annealing and extending DNA fragments. Researchers reviewed this laboratory process and illustrated the clinical applications of PCR in the rapid detection of infections due to Chlamydia, mycoplasmas, mycobacteria, herpesviruses and enteroviruses. CMAJ 2000;163(3):301-9.

Hepatitis B and EEGs

In early 1996 an investigation of an outbreak of hepatitis B identified 75 cases among patients who had attended six electroencephalogram (EEG) clinics between 1990 and 1996. The same technician had performed all of the EEGs and was found to be positive for hepatitis. The Hepatitis B Outbreak Investigation Team reported that subdermal EEG electrodes were the likely vehicles of transmission from the technician. It reports that the cases demonstrate the need for stringent infection control, the desirability of noninvasive techniques (such as disk electrodes) and the importance of hepatitis B vaccination. CMAJ 2000:162(8):1127-31.

Hepatitis C: notifying patients at risk

Although one of the major risk factors for developing hepatitis C (HCV) is the receipt of blood or blood products, many patients do not even know they have received transfusions. To ensure that patients knew they were at risk for HCV from transfused blood, the Prince Edward Island Department of Health and Social Services launched a province-wide program in 1998 to notify patients who received blood between January 1984 and June 1990. The authors report the program successfully contacted 82% of the patients who received blood or blood products. Before the notification program, only 4.1% of PEI recipients of blood or blood products had undergone HCV testing. After completion of the notification program, 91.2% had been either tested, had died, or had moved out of the province. The notification program also identified the majority of PEI’s transfusion-related cases of hepatitis C. CMAJ 2000;162(2):199-202.

HIV complacency

The first year’s follow-up results of a prospective study involving 681 young gay and bisexual men in Vancouver revealed a high incidence of HIV infection and a disturbing trend toward increasing levels of unprotected anal sex. Over a total of 638.63 person-years, 11 men became seropositive between enrolment and follow-up, for an overall HIV incidence rate of 1.7 per 100 person-years. This rate rose to 9.5 per 100 person-years among those who exchanged sex for money, good or drugs. Of the 232 men with casual partners who reported having protected anal sex in the year before enrolment, 43 (18.5%) reported at least one episode of unprotected anal sex in the subsequent year. Have advances in HIV therapy engendered complacency in this cohort? CMAJ 2000;162(1):21-5.

A related editorial warns that although advances in knowledge have produced dramatic reductions in the rates of AIDS and AIDS-related deaths, wealthy nations must not be lulled into viewing HIV infection as a manageable chronic illness. The worldwide prevalence of over 26 million and low compliance with complex drug regimens among poor people and injection drug users exacerbates the HIV situation. CMAJ 2000;162(1):52-3.

Immune in the womb

A new vaccination technique developed by Saskatchewan researchers could one day protect fetuses against infectious diseases such as AIDS and hepatitis B. CMAJ 2000;163(8):1032.

Preventing perinatal transmission of HIV

Researchers reviewed the records for 71 children born in northern Alberta to 54 HIV-positive women from January 1988 to December 1999 and found HIV infection was diagnosed before labour in 43 women. Even though only about six% of the total population of northern Alberta are Aboriginal, the authors report that most (68%) of the children in the study were Aboriginal. The authors also found a high rate of concurrent hepatitis C (62%) among the Aboriginal mothers, and suggest that injection drug use is an important risk factor among Aboriginal women in northern Alberta. A subgroup of women received antiretroviral agents both during pregnancy and intrapartum; 86% (31/36) of their babies were HIV negative. All infants received at least some zidovudine orally in the first six weeks of life, except for two whose mothers refused treatment.

The authors state that their study shows that HIV screening is useful, particularly given the availability and effectiveness of treatments to prevent perinatal transmission of HIV. The authors also suggest that their findings demonstrate the need for public health programs aimed at reducing the burden of HIV and hepatitis C among Aboriginal women of reproductive age. CMAJ 2000;163(7):831-3.

Rapid HIV test creates ethical concerns

A new HIV test that provides results in just 15 minutes is undoubtedly more convenient and faster, but observers say it also raises concerns about appropriate counselling, administration of the test and way to deal with false-positive results. CMAJ 2000;162(11):1600.

A related editorial says the rapid tests pose no threat and should be available for home use. CMAJ 2000;162(11):1545.

Respiratory tract infections in nursing homes

Identifying and responding quickly to outbreaks of respiratory tract infections among patients in long-term care facilities for older people can be a matter of life and death. Reports of pneumonia rates as high as 42% and case-fatality rates exceeding 70% in outbreaks due to the influenza virus led researchers to examine the frequency and epidemiologic features of respiratory tract infections in five nursing homes in Toronto over a three-year period. The authors report that despite identifying the clinical manifestations of infected residents and conducting microbiological investigations for causal agents, 65% of the outbreaks were not detected until a retrospective review of recorded symptoms was completed. While the authors were reassured that all influenza outbreaks were identified prospectively, they conclude that there is substantial room for improvement in surveillance. They tout the importance of appropriate diagnostic testing to find the cause of the infection sooner, which will allow appropriate treatment to begin sooner. An important tool in the early detection arsenal is taking an adequate number of nasopharyngeal swabs during an outbreak. CMAJ 2000;162(8):1133-7.

Treating TB from beyond Canadian borders

The immigrant population in Canada and other developed countries is known to be at risk for tuberculosis. Researchers analyzed data from the Ontario Reportable Disease Information Service and the Citizenship and Information database to identify higher risk groups within this population. A total of 1,341 cases of tuberculosis in foreign-born people were reported in Ontario in 1994–1995 and of that number, 602 were eligible for analysis. The authors report that the two strongest determinants of risk are referral for medical surveillance by immigration officials and world region of origin. Immigrants from Vietnam had the highest incidence of tuberculosis, and accounted for 107 (17.8%) of all the 602 cases. The authors support current recommendations for focusing preventive strategies on people referred to local health authorities by immigration officials, but warn opportunities to prevent future cases of tuberculosis may be lost.

"The current system has a number of shortcomings, including the lack of notification of the appropriate Canadian public health authorities, poor adherence to the guidelines for medical surveillance in Canada, and low rates of preventive therapy among those referred for surveillance," state the authors. CMAJ 2000;163(7):823-8.

Urine samples used to test for STDs

Saskatchewan’s provincial laboratory has become the first in the country to use urine samples to conduct all chlamydia and gonorrhea tests. The move is expected to save money through earlier detection and treatment of sexually transmitted diseases. CMAJ 2000;163(10):1332.

West Nile fever scare

West Nile fever, caused by a member of the flavivirus family, had never been isolated in the Western Hemisphere prior to six cases in New York City in August 1999. All six patients had encephalitis caused by the West Nile virus. A paper in CMAJ looked at the management and prevention of West Nile fever. CMAJ 2000;162(7):1036.

What dictates hospital admission?

As the CD4 cell count decreases and the viral load increases, an HIV-positive person becomes increasingly susceptible to opportunistic infections that may result in admission to hospital. While the existing staging systems for people with AIDS rely on physiologic and diagnostic information, the decision to use hospital services or other medical resources has been shown to be influenced by social factors or measures of the patient’s ability to function at certain levels at disability. Researchers studied 947 HIV-positive men and women to evaluate the demographic and clinical determinants of admission to hospital among HIV-positive men and women receiving antiretroviral therapy in British Columbia. They found that 17% of the participants were admitted to hospital during the study period (May 1, 1996 to March 31, 1997). Hospital admission was associated with being unemployed (82% of those admitted v. 58% of those not admitted), being an injection drug user (24% v. 17%), reporting a poor health status (46% v. 29%), and having a physician experienced in the management of HIV/AIDS (31% v. 24%). Examination of clinical determinants demonstrated that hospital admission was associated with a previous admission (72% v. 46%), a high viral load, a low CD4 count and an AIDS diagnosis. CMAJ 2000;162(6):783-6.

Drug-resistant tuberculosis

A review of the mechanisms and theory behind current strategies for tuberculosis control describes how substandard treatment results in the selection of drug-resistant strains. Acquired resistance arises in developing countries owing to scarce resources and difficult access to health care, and in developed countries owing to difficulties in monitoring compliance with drug therapy. Individual risk factors include living in high-prevalence areas, exposure to resistant strains and previous antituberculous drug therapy. Treatment depends on state-of-the-art drug susceptibility testing and an uninterrupted supply of a wide range of drugs. In TB control programs, prevention should be given priority, with appropriate prescription of two or more agents and careful monitoring of compliance. CMAJ 2000;163(4):425-8.

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