Dennis K. M. Ip

Predictors and Consequences of In-hospital Formula Supplementation for Healthy Breastfeeding Newborns

Background: Although exclusive breastfeeding is recommended for the first 6 months, the use of breast milk substitutes is widespread around the world. Objectives: To describe the patterns of infant formula supplementation among healthy breastfeeding newborns, to identify factors contributing to in-hospital formula supplementation, and to assess the dose-response relationship between the amount of in-hospital formula supplementation and the duration of any breastfeeding. Methods: A sample of 1246 breastfeeding mother–infant pairs was recruited from 4 public hospitals in Hong Kong and followed prospectively for 12 months or until weaned. Multiple logistic regression analysis was used to examine factors associated with in-hospital supplementation. Cox regression analysis was used to explore the impact of in-hospital supplementation on breastfeeding duration. Results: Of the total, 82.5% of newborns were supplemented in the hospital; one-half received formula within 5 hours of birth. Assisted vaginal delivery (odds ratio [OR] = 2.06, 95% confidence interval [CI] 1.03, 4.15), cesarean section (OR = 3.45, 95% CI 1.75, 6.80), and higher birth weight (OR = 1.56, 95% CI 1.12, 2.18) were positively associated with in-hospital formula supplementation, whereas initiating breastfeeding in the delivery room (OR = 0.55, 95% CI 0.33, 0.89) was associated with decreased likelihood of in-hospital supplementation. Any infant formula in the first 48 hours was associated with a shorter duration of breastfeeding (hazard ratio [HR] = 1.51, 95% CI 1.27, 1.80), but there was no dose-response effect. Conclusion: In-hospital formula supplementation is common in Hong Kong hospitals and appears to be detrimental to breastfeeding duration. Continued efforts should be made to avoid the provision of infant formula to breastfeeding babies while in the hospital unless medically indicated.

A profile of the online dissemination of national influenza surveillance data

BackgroundInfluenza surveillance systems provide important and timely information to health service providers on trends in the circulation of influenza virus and other upper respiratory tract infections. Online dissemination of surveillance data is useful for risk communication to health care professionals, the media and the general public. We reviewed national influenza surveillance websites from around the world to describe the main features of surveillance data dissemination.MethodsWe searched for national influenza surveillance websites for every country and reviewed the resulting sites where available during the period from November 2008 through February 2009. Literature about influenza surveillance was searched at MEDLINE for relevant hyperlinks to related websites. Non-English websites were translated into English using human translators or Google language tools.ResultsA total of 70 national influenza surveillance websites were identified. The percentage of developing countries with surveillance websites was lower than that of developed countries (22% versus 57% respectively). Most of the websites (74%) were in English or provided an English version. The most common surveillance methods included influenza-like illness consultation rates in primary care settings (89%) and laboratory surveillance (44%). Most websites (70%) provided data within a static report format and 66% of the websites provided data with at least weekly resolution.ConclusionAppropriate dissemination of surveillance data is important to maximize the utility of collected data. There may be room for improvement in the style and content of the dissemination of influenza data to health care professionals and the general public.

Viral genetic sequence variations in pandemic H1N1/2009 and seasonal H3N2 influenza viruses within an individual, a household and a community

BACKGROUNDnThere are few data in the literature on viral sequence variation between host generations/successive transmission events. Relatively little is known about the sequence heterogeneity of the influenza viruses transmitted within families.nnnOBJECTIVESnTo study the molecular epidemiology of influenza virus and to determine the sequence variation within an individual, a household and a community during the first wave of influenza pandemic in 2009.nnnSTUDY DESIGNnA prospective study of household transmission of influenza A in Hong Kong was conducted during the pandemic in 2009. The HA and NA sequences of pandemic and seasonal influenza A viral isolates identified in this household transmission study were sequences and analyzed.nnnRESULTSnOur results indicated that there were multiple introductions of influenza viruses into Hong Kong. Sequence analysis of these isolates suggested that members of these family clusters acquired the infection by household transmissions. Interestingly, unlike those concluded from previous household transmission studies, we observed sequence variations between sequential samples from the same person and also within the same household.nnnCONCLUSIONSnFamily clusters of influenza A viral infection are predominantly the result of secondary transmission within a household. Our results also suggested that the intra-host viral sequence variation might be more common that than previously thought.

Preservation of lower incidence of chronic lymphocytic leukemia in Chinese residents in British Columbia: a 26-year survey from 1983 to 2008

Abstract The incidence of chronic lymphocytic leukemia (CLL) in the Asian population is up to 10 times lower than that in Caucasians. Studies on CLL in Asian residents in North America may help to determine the relative genetic and environmental causes of such a difference. Computerized records of CLL incidence from the combined British Columbia (BC) databases (n = 2736) and the Hong Kong Cancer Registry (HKCR, n = 572) were traced. Ethnic Chinese cases of CLL in BC were identified (n = 35). The world age standardized rates (WASRs) of CLL (per 100 000) were calculated in BC (1.71), HK (0.28) and BC Chinese (0.4), respectively. Using standard incidence ratios (SIRs), the observed BC Chinese case number was comparable to the figure projected from HK rates (SIR 1.3, p = 0.1) but significantly lower than the figure following BC rates (SIR 0.22, p < 0.0001). The difference was maintained over both genders, in all age groups and through the years. Our data over three decades suggest that genetic factors outplay environmental factors to give lower CLL rates in Chinese.

Subtype-specific incidence rates of lymphoid malignancies in Hong Kong compared to the United States, 20012010

Clinical studies of lymphoid malignancies (LMs) have suggested that the descriptive patterns of LMs differ in East Asia compared to Western populations. However, there are very limited available data on population-based, subtype-specific incidence rates of LMs in the East Asian population, particularly in Chinese. Using data from the Hong Kong (HK) Cancer Registry and United States (U.S.) SEER Program, we calculated and compared age-adjusted incidence rates of LM subtypes in HK to those in Whites and Asians living in the U.S. Overall and sex-specific rates were calculated for the period 2001-2010. The incidence of most subtypes was low in the HK population, with rates <1 case per 100,000 for all subtypes except for diffuse large B-cell lymphoma (3.26/100,000) and plasma cell neoplasms (1.99/100,000). Age-adjusted incidence rates of all evaluated B-cell subtypes were significantly higher in U.S. Whites compared to HK, with standardized rate ratios (SRRs) ranging from 1.6 (Burkitt lymphoma) to 9.1 (chronic lymphocytic leukemia/small lymphocytic lymphoma). Rates in U.S. Asians were generally intermediate to those in U.S. Whites and HK. Conversely, rates of extranodal NK/T-cell lymphoma were significantly lower in both U.S. Whites (SRR=0.2) and U.S. Asians (SRR=0.5) compared to HK. Our data provide new insight into the subtype-specific patterns of LMs in the Chinese population, and suggest the need for etiological studies of LMs in the East Asian population to elucidate the factors responsible for these differences in the geographic incidence patterns.

Seroprevalence of Pandemic H1N1 Antibody among Health Care Workers in Hong Kong Following Receipt of Monovalent 2009 H1N1 Influenza Vaccine

Background Healthcare workers in many countries are recommended to receive influenza vaccine to protect themselves as well as patients. A monovalent H1N1 vaccine became available in Hong Kong in December 2009 and around 10% of local healthcare workers had received the vaccine by February 2010. Methods We conducted a cross-sectional study of the prevalence of antibody to pandemic (H1N1) 2009 among HCWs in Hong Kong in February–March 2010 following the first pandemic wave and the pH1N1 vaccination campaign. In this study we focus on the subset of healthcare workers who reported receipt of non-adjuvanted monovalent 2009 H1N1 vaccine (Panenza, Sanofi Pasteur). Sera collected from HCWs were tested for antibody against the pH1N1 virus by hemagglutination inhibition (HI) and viral neutralization (VN) assays. Results We enrolled 703 HCWs. Among 104 HCWs who reported receipt of pH1N1 vaccine, 54% (95% confidence interval (CI): 44%–63%) had antibody titer ≥1∶40 by HI and 42% (95% CI: 33%–52%) had antibody titer ≥1∶40 by VN. The proportion of HCWs with antibody titer ≥1∶40 by HI and VN significantly decreased with age, and the proportion with antibody titer ≥1∶40 by VN was marginally significantly lower among HCWs who reported prior receipt of 2007–08 seasonal influenza vaccine (odds ratio: 0.43; 95% CI: 0.19–1.00). After adjustment for age, the effect of prior seasonal vaccine receipt was not statistically significant. Conclusions Our findings suggest that monovalent H1N1 vaccine may have had suboptimal immunogenicity in HCWs in Hong Kong. Larger studies are required to confirm whether influenza vaccine maintains high efficacy and effectiveness in HCWs.

The epidemiological and public health research response to 2009 pandemic influenza A(H1N1): experiences from Hong Kong

In recent years, Hong Kong has invested in research infrastructure to appropriately respond to novel infectious disease epidemics. Research from Hong Kong made a strong contribution to the international response to the 2009 influenza A (H1N1) pandemic (pH1N1). Summarizing, describing, and reviewing Hong Kong’s response to the 2009 pandemic, this article aimed to identify key elements of a real‐time research response. A systematic search in PubMed and EMBASE for research into the infection dynamics and natural history, impact, or control of pH1N1 in Hong Kong. Eligible articles were analyzed according to their scope. Fifty‐five articles were included in the review. Transmissibility of pH1N1 was similar in Hong Kong to elsewhere, and only a small fraction of infections were associated with severe disease. School closures were effective in reducing pH1N1 transmission, oseltamivir was effective for treatment of severe cases while convalescent plasma therapy has the potential to mitigate future pandemics. There was a rapid and comprehensive research response to pH1N1 in Hong Kong, providing important information on the epidemiology of the novel virus with relevance internationally as well as locally. The scientific knowledge gained through these detailed studies of pH1N1 is now being used to revise and update pandemic plans. The experiences of the research response in Hong Kong could provide a template for the research response to future emerging and reemerging disease epidemics.

Lower incidence of plasma cell neoplasm is maintained in migrant Chinese to British Columbia: findings from a 30-year survey

Abstract The etiology of plasma cell myeloma (PCM) is largely unknown. Its incidence varies widely in different ethnic groups. Migrant study may help determine the relative contributions of genetic versus environmental factors to PCM pathogenesis. We performed a retrospective review of the computerized records of all patients diagnosed with PCM between 1975 and 2004 in British Columbia (BC), and identified patients of Chinese ethnicity. This was compared with PCM incidence in Hong Kong (HK) Chinese. Age distributions of HK, BC and BC Chinese populations were obtained from the census departments to calculate world age-standardized rates (WASRs). The WASR of PCM over the 30-year period in BC Chinese was 1.64/100 000 person-years (95% confidence interval [CI] 1.37–1.93). This was similar to the WASR observed in HK (1.78, 95% CI 1.73–1.83), with a standardized incidence ratio (SIR) of 0.91 (95% CI 0.74–1.10). The rate was much lower than that in the BC non-Chinese background population (WASR 3.59, 95% CI 3.50–3.68; SIR 0.46, 95% CI 0.38–0.56). The lower rates in BC Chinese were maintained across all years, both genders and in all age groups above 45 years. Our observations suggest a strong genetic component as the cause of differences in the ethnic predisposition to PCM.

Outcomes and Susceptibility to Neuraminidase Inhibitors in Individuals Infected With Different Influenza B Lineages: The Influenza Resistance Information Study

BACKGROUNDnLittle is known about how influenza infections caused by B/Victoria and B/Yamagata virus lineages compare with respect to disease course and susceptibility to antiviral therapy.nnnMETHODSnData from patients with influenza B infections from the first 5 years (2009-2013) of the prospective Influenza Resistance Information Study (IRIS, NCT00884117) were evaluated. Cultured viruses were phenotypically tested for neuraminidase inhibitor (NAI) sensitivity, and sequenced to determine virus lineage (B/Victoria or B/Yamagata). Differences in clinical outcomes (viral clearance and symptom resolution) between virus lineages were assessed using Kaplan-Meier analysis.nnnRESULTSnIn all, 914 patients were positive for influenza B by reverse transcriptase polymerase chain reaction (nnnRT-PCRnB/Victoria, 586; B/Yamagata, 289; not subtyped, 39); 474 were treated with antivirals. No phenotypic resistance to oseltamivir or zanamivir was found in B/Victoria or B/Yamagata viruses. Of 15 predefined resistance mutations, 2 were detected by neuraminidase sequencing: I221T had reduced sensitivity to oseltamivir, and I221V was sensitive to NAI inhibition. No consistent differences between virus lineages in times to viral clearance or to symptom or fever resolution were found in adults and adolescents or in children.nnnCONCLUSIONSnInfluenza B virus lineage had no notable effect on disease outcomes or antiviral susceptibility in this population.

A Foodborne Outbreak of Gastroenteritis Caused by Vibrio parahaemolyticus and Norovirus through Non-Seafood Vehicle.

Foodborne outbreaks caused by a mixed infection of Vibrio parahaemolyticus and norovirus have rarely been described. We reported a mixed outbreak of Vibrio parahaemolyticus and norovirus causing acute gastroenteritis in 99 staff members of a company in Guangdong, China, in May 2013, following consumption of roasted duck, an uncommon non-seafood vehicle for such mixed infection, in one meal served in the companys catering service. Epidemiological and laboratory findings indicated that a single asymptomatic food handler was the source of both pathogens, and the high rate of infection of both pathogens was exacerbated by the setting’s suboptimal food hygiene practice.