Faculty peer reviewed
This week’s edition of PrimeCuts will focus on an old friend, influenza, as well as a couple of other viruses. The novel swine-origin influenza A (H1N1) pandemic has no signs of decreasing its intensity. The New York Times reports on the pandemic reaching India, with nearly 1,200 cases and at least 17 deaths reported thus far. As the flu spreads in the southern hemisphere, the US prepares for a resurgence this fall.
The New England Journal of Medicine features 2 articles this week about H1N1. Chowell and colleagues reviewed Mexican national registries and detected a sudden age shift in the cases of severe pneumonia early in the pandemic, with 72% of such cases involving patients aged 5-59, compared with 32% in the reference period. The second article, by Perez-Padilla and colleagues, supports these epidemiologic findings by reporting a case series of the first 18 cases of pneumonia and confirmed H1N1 infection hospitalized in Mexico City between March and April of 2009. More then half of patients were young (13-47 years), 12 required mechanical ventilation, and 7 died. This case series also highlights the ability of the infection to cause a severe, potentially fatal disease in young previously healthy patients (only 8 out of the 18 had pre-existing medical conditions).
The Lancet also addresses the new flu. It recently published an early online viewpoint on surveillance of the pandemic, where the authors recognize that it is impractical to investigate every single case with respiratory symptoms for the novel H1N1 virus. These authors favor more selected testing with targeted virus isolation and appropriate sampling of selected severe and mild cases, arguing that this approach will render more accurate data. Also in The Lancet, investigators from the CDC report on the particular tendency of this pandemic to affect pregnant women. Out of 34 cases identified in pregnant women in the US between April and May, 2009, one third were hospitalized. From population data, it also appears that admission rates for pregnant women are higher than the general population (0.32 vs 0.076/100,000). It looks like this is enough data to treat pregnant women with prompt Tamiflu.
Not surprisingly, Annals of Internal Medicine this week features a randomized trial on using hand hygiene and facemasks to prevent the flu. In this study, Cowling and others studied 407 patients from Hong Kong with confirmed influenza A or B infection and their household contacts, and found that the intervention group (contacts that used hand hygiene plus facemasks) was at reduced risk of infection with an odds-ratio of 0.33. Interestingly, the intervention group used liquid hand soap, alcohol hand rub, and regular surgical facemasks (I always thought that anything less then N95 respirators was useless!). Also focusing on prevention, Khazeni and colleagues review available data on the use of oseltamivir and zanamivir for greater then 4 weeks as a chemoprophylaxis against the flu. They found that the intervention works, but the trials examined were all funded by industry, were not powered to detect adverse effects, and racial groups and children as well as immunocompromised subjects were underrepresented. I wonder if one will be given the option of taking prolonged Tamiflu instead of the vaccine, if his/her fear from vaccine side effects is greater then the drug cost…
The British Medical Journal features a meta-analysis of treatment and prophylaxis of influenza in children. The authors found that treatment with oseltamivir or zanamivir decreased outpatient children’s flu symptoms by an average of 1 day, and a post-exposure prophylaxis with a 10-day course decreased risk by 8%. Of note, none of the included trials evaluated the current H1N1 influenza strain.
A little more about influenza. The CDC published a report in MMWR that rapid flu tests are not very sensitive against the H1N1 strain (40-69% overall sensitivity, better in cases with high levels of virus), and recommend rRT-PCR or virus isolation techniques in cases that a more definitive answer is needed.
Now let’s move on to polio. In a news report, Science magazine tells the story of a type 2 polio outbreak in Nigeria. Since 1999 when the poliovirus type 2 was considered eradicated worldwide, Nigeria changed the vaccination strategy from the trivalent oral polio vaccine to monovalent ones targeting types 1 and 3. Now, this year through July, there are 124 reported cases of paralysis caused by the type 2, compared to 30 during the same period last year. This new outbreak of type 2 comes from a novel mutation from a vaccine virus, in other words, the attenuated virus regained the ability to cause neurologic damage. Nigerian authorities are still deciding if using a trivalent oral polio vaccine or switching altogether to the dead virus IPV would be the best option, but the most important part of the plan is how to reach enough children with either vaccine.
Finally, Nature Medicine features several excellent studies on HIV and SIV biology. In one of the articles that reached the news, a group of French scientists reported a new HIV-1 virus lineage that is related to gorilla SIV. There are 3 known HIV-1 groups, M, N, and O (main, outlier, and non-m/non-o), and they are all closely related to chimpanzee SIV. The group proposes to call the newly discovered gorilla-related HIV-1 as group P. This study highlights the need for continued surveillance of new HIV strains, particularly in Africa since it may be the originating source of HIV. The remaining question, what P stands for, the authors answer by referencing Robertson and colleagues, who suggested just to continue the alphabetical order…
Dr. Saraiva is a second year resident at NYU Medical Center. Peer reviewed by Dr. Danise Schiliro-Chuang, an Associate Program Director in the NYU SOM Internal Medicine Residency Training Program.
1. Chowell G, Bertozzi SM, Colchero A, Lopez-Gatell H, Alpuche-Aranda C, Hernandez M, Miller MA. Severe respiratory disease concurrent with the circulation of H1N1 influenza. N Eng J Med 2009, 361:674-9.
2. Perez-Padilla R, Rosa-Zamboni DD, Leon SP, Hernandez M, Quinones-Falconi F, Bautista E, Ramirez-Venegas A, Rojas-Serrano J, Ormsby CE, Corrales A, Higuera A, Mondragon E, Cordova-Villalobos JA. Pneumonia and respiratory failure from swine-origin influenza A (H1N1) in Mexico. N Eng J Med 2009, 361:680-9.
3. Lipsitch M, Hayden FG, Cowling BJ, Leung GM. How to maintain surveillance for novel influenza A H1N1 when there are too many cases to count. Lancet 2009, early online publication (Aug 12 2009), doi:10.1016/S0140-6736(09)61377-5.
4. Jamieson DJ, Honein MA, Rasmussen SA, Williams JL, Swedlow DL, Biggerstaff MS, Lindstrom S, Louie JK, Christ CM, Bohm SR, Fonseca VP, Ritger KA, Kuhles DJ, Eggers P, Bruce H, Davidson HA, Lutterloh E, Harris ML, Burke C, Cocoros N, Finelli L, MacFarlane KF, Shu B, Olsen SJ. H1N1 2009 influenza virus infection during pregnancy in the USA. Lancet 2009, 374:451-8.
5. Cowling BJ, Chan K-H, Fang VJ, Cheng CKY, Fung ROP, Wai W, Sin J, Seto WH, Yung R, Chu DWS, Chiu BCF, Lee PWY, Chiu MC, Lee HC, Uyeki TM, Houck PM, Peiris JSM, Leung GM. Facemasks and hand hygiene to prevent influenza transmission in households. Ann Intern Med 2009, online-early article August 3 2009, PMID: 19652172.
6. Khazeni N, Bravata DM, Holty JE, Uyeki TM, Stave CD, Gould MK. Safety and efficacy of extended-duration antiviral chemoprophylaxis against pandemic and seasonal influenza. Ann Intern Med 2009, online-early article August 3 2009, PMID: 19652173.
7. Shun-Shin M, Thompson M, Heneghan C, Perera R, Harnden A, Mant D. Neuraminidase inhibitors for treatment and prophylaxis of influenza in children: systematic review and meta-analysis of randomized controlled trials. BMJ 2009, 339:b3172.
8. Centers for Disease Control and Prevention (CDC). Evaluation of rapid influenza diagnostic tests for detection of novel influenza A (H1N1) virus – United States, 2009. MMWR Morb Mortal Wkly Rep 2009, 58:826-9.
9. Roberts L. Type 2 poliovirus back from the dead in Nigeria. Science 2009, 325:660-1.
10. Plantier J-C, Leoz M, Dickerson JE, Oliveira FD, Cordonnier F, Lemée V, Damond F, Robertson DL, Simon F. A new human immunodeficiency virus derived from gorillas. Nat Med 2009, 15:871-2.
11. Robertson DL, Anderson JP, Bradac JA, Carr JK, Foley B, Funkhouser RK, Gao F, Hahn BH, Kalish ML, Kuiken C, Learn GH, Leitner T, McCutchan F, Osmanov S, Peeters M, Pieniazek D, Salminen M, Sharp PM, Wolinsky S, Korber B. HIV-1 nomenclature proposal. Science 2000, 288:55-6.