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By Carol A. Kemper, MD, FACP, Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases; Santa Clara Valley Medical Center, Section Editor, Updates; Section Editor, HIV, is Associate Editor for Infectious Disease Alert.
Once Again — The Flu is Upon Us
Sources: CDC. Weekly Report: Influenza Summary Update 2008-2009 Influenza Season week 4, ending January 31, 2009. Available at http://www.cdc.gov/flu/weekly; More resistance to Oseltamivir (tamiflu). The Medical Letter. 2009;51:5-6; ProMED-mail post, February 3, 2009; http://www.promedmail.org.
Preliminary data from this year's flu season indicates that another mismatch may be occurring between this year's vaccine and the predominant circulating strains of influenza A and influenza B viruses. Despite the administration of 3.2 million doses of influenza vaccine this year, cases of influenza continued to increase in the United States throughout the month of January. US virologic surveillance data for the first four weeks of this year indicate that upwards of 60% of circulating influenza A isolates and 70% of circulating influenza B isolates may not be covered by the current vaccine.
Of the 792 isolates examined this year, 85% are influenza A strains and 15% are influenza B. Of the influenza A strains, 75% are unsubtyped, 22% are H1N1, and 3% are H3N2 (generally consider to be more severe). Of the 142 influenza A H1N1 and 35 H3N2 isolates examined, all appear to be related to components in the existing vaccine. However, 55 of 78 influenza B strains (70.5%) examined were not related to the current vaccine strain (B/Florida/04/2006) — most were B/Victoria-related strains.
Each year, vaccine manufacturers depend on data provided to them by the World Health Organization, in order to construct the trivalent influenza vaccine, using three of the more common influenza strains circulating in Europe, and coming westward. This article, which was abstracted from a Taiwanese newspaper for ProMEDmail, proposes that vaccine manufacturers redirect their focus to isolates emerging from Asia rather Europe. In other words, manufacturers should start looking for isolates moving eastward, especially from Korea and China. Researchers in 2005 indicated that Asian isolates from these countries lead the wave of infections in the United States by as much as six months to two years.
The CDC announced on February 3, 2009, that circulating influenza A virus has jumped from 11% resistance to oseltamivir (Tamiflu) last year to an astounding 97% this year. Of those influenza A H1N1 isolates tested for resistance this year, 185 of 190 (97.4%) were resistant to oseltamivir, none were resistant to zanamivir, and 1.1% were resistant to amantadine. None of the 41 H3N2 influenza A strains were resistant to oseltamivir and 100% were resistant to amantadine; none of 77 influenza B isolates were resistant to oseltamivir. This sudden shift in resistance over the past year has come as a surprise, but experts suggest that it does not reflect the broader use of these antiviral agents in the United States; rather, the mutability of this virus and the hardiness of these newer strains. A similar phenomenon has been observed in some European countries, especially in Norway, where it is believed there has been minimal selective pressure from the infrequent use of Tamiflu.
These data leave physicians wondering what agents to select in the treatment of influenza this season. Oseltamivir is easier to prescribe, because it's oral and can be given to children over one year of age. One expert suggests that a safe bet is to prescribe both amantadine or rimantidine plus oseltamivir, hoping that at least one will work. The Medical Letter proposed treatment with both types of agents if the circulating strains in your community are known to be influenza A H1N1 virus. But oseltamivir alone would be sufficient if the predominant strains were known to be influenza A H3N2 strains or influenza B strains. Since information on circulating strain subtypes is seldom quickly available for a given community, it seems that both agents may be necessary for adequate coverage. Dr. Julie Geberding at the CDC was quoted as saying this (resistant) strain "may still fizzle out," and no changes were being made in their treatment recommendations.
One other thought: although the rapid EIA test is cost effective and, well, rapid, continuing to obtain viral cultures for epidemiologic purposes is critical. None of this information above would have been recognized if cultures had not been obtained.
Young People — Discounting Their Futures
Source: HIV infection among young black men who have sex with men — Jackson, Mississippi, 2006-2008. MMWR. 2009;58;77-81.
Each month at the county clinic in San Jose, there is a small parade of mostly stunned-looking people — some are pregnant, some are meth users, some are in their early 20s, or even their teens — and all have just found out they are HIV+. What this article describes in Jackson, MS, is, I suspect, occurring in many parts of the United States.
Following a 20% increase in HIV infection among black men in the Jackson area between 2004-2005 and 2007, most of which occurred in young men aged 17-25 years, these investigators conducted an in-depth investigation of risk factors and behaviors. Attempts to survey these newly diagnosed individuals yielded about 90 individuals, about half of whom declined to participate or could not be located. Of the remaining 40 persons, 29 agreed to participate in this survey.
Their median age was 22 years (range 17-25 years). This is in stark contrast to the average age of HIV+ persons in the United States generally runs in the late 30s. Two-thirds self identified as MSM (a man who had had anal sex with a man), 24% as bisexual, 7% as straight, and 3% as questioning. Two-thirds reported unprotected sex with one or more male partners within the previous 12 months, and more than half had been involved with an older man (> 26 years of age). In the preceding 12 months, the number of sex partners varied from 1-11 (median, 3.5). Ten percent reported sexual relationships with one or more women. Studies suggest that young men are much more likely to acquire HIV infection from relationships with older men.
When asked whether they thought their chances of acquiring HIV infection was likely, somewhat likely, unlikely, or very unlikely, more than half thought it unlikely or very unlikely. At least 20% had never been tested for HIV before learning they were positive.
The authors maintain that prevention strategies should be revised/adapted to suit young men, who perceive their risk of acquiring HIV as minimal. But there is the rub — how do you change behavior if the perceived risk is low? In some ways, it's really an economic equation, not a societal or behavioral one; young people who discount their future are less invested in the long term. What happens today is much more important. Increasing availability of testing, or implementation of universal screening, may identify some patients sooner. But I've heard patients rationalize that their prior negative HIV tests made them feel "safe." They had previously gotten away with risky behavior, so why play it safe?
And, Around the World. . .
Source: Njue A, et al. Disco funerals: a risk situation for HIV infection among youth in Kisumu, Kenya. AIDS. 2009; 23:253-255.
In Kenya, where the prevalence of HIV infection runs anywhere from 10%-30% in most communities, funerals are common. But in an interesting twist, reminiscent of the macabre nights of the Day of the Dead or Mardi Gras, funerals are becoming big business, with up to 100 family and friends gathering to celebrate the life of their family member or friend, and to party. Families of the deceased host large gatherings as a way to raise funds for funeral expenses, complete with party favors and disc jockeys. People party, dance, and drink for days, sometimes up to two weeks. Sex is apparently commonplace, much of it unprotected and some of it coerced. It's considered a way to meet the neighbors, especially for young people, who are often left unattended.
These authors interviewed 44 young female and male participants, and observed six "disco matanga" or disco funerals. During their trip to this part of Kenya, about three disco funerals were held per week. Casual sex, even group sex, is common, and apparently condoned by older members of the family as a way to experiment. Many forego condoms in the interest of convenience. After conducting numerous interviews, the authors believe that alcohol plays a significant role in forced sex, especially with underage or teenage girls. Other studies have shown that young women who accept gifts, such as a drink or a ride home, have lost their bargaining power and cannot refuse sex or insist on condoms.
The authors caution that these events must be viewed in light of the cultural customs of this part of Kenya, where polygamy is common and premarital sex is condoned as a way to experiment and to get to know a future partner. The funerals are generally seen as a form of celebration. But these types of venues, similar to bare-backing parties in San Francisco, or large club gatherings, carry the same risk of rapid spread of HIV infection within a group in a very short time.