In Australia, the outbreak of pandemic (H1N1) 2009 began in Melbourne, Victoria; in the first 17 days, the Victorian Infectious Diseases Reference Laboratory detected 977 cases. Although the laboratory had a pandemic plan in place, a retrospective evaluation found 3 major variations from plan assumptions: 1) higher peak demand not limited by a case definition, 2) prolonged peak demand because containment attempts continued despite widespread influenza, and 3) unexpected influence of negative test results on public health actions. Although implementation of the plan was generally successful, the greatest challenges were limited availability of skilled staff and test reagents. Despite peak demand of 1,401 tests per day, results were provided within the usual 24 hours of specimen receipt; however, turnaround time seemed slower because of slow transport times (>3 days for 45% of specimens). Hence, effective laboratory capability might be enhanced by speeding transport of specimens and improving transmission of clinical data.

Two cases of multidrug-resistant tuberculosis (MDR TB) in a household are assumed to reflect within-household transmission. However, in high-incidence areas of MDR TB, secondary cases may arise through exposure to MDR TB in the community. To estimate the frequency of multiple introductions of MDR TB into households, we used spoligotyping and 24-loci mycobacterial interspersed repetitive unit–variable number tandem repeats to classify isolates from 101 households in Lima, Peru, in which >1 MDR TB patient received treatment during 1996–2004. We found different MDR TB strains in >10% of households. Alternate approaches for classifying matching strains produced estimates of multiple introductions in <38% of households. At least 4% of MDR TB patients were reinfected by a second strain of MDR Mycobacterium tuberculosis. These findings suggest that community exposure to MDR TB in Lima occurs frequently. Rapid drug sensitivity testing of strains from household contacts of known MDR TB patients is needed to identify optimal treatment regimens.

We compared 30-day case-fatality rates for patients infected with Clostridium difficile possessing genes for toxins A and B without binary toxin (n = 212) with rates for patients infected with C. difficile possessing genes for A, B, and binary toxin. The latter group comprised patients infected with strains of PCR ribotype 027 (CD027, n = 193) or non-027 (CD non-027, n = 72). Patients with binary toxin had higher case-fatality rates than patients without binary toxin, in univariate analysis (relative risk [RR] 1.8, 95% confidence interval [CI] 1.2–2.7) and multivariate analysis after adjustment for age, sex, and geographic region (RR 1.6, 95% CI 1.0–2.4). Similar case-fatality rates (27.8%, 28.0%) were observed for patients infected with CD027 or CD non-027. Binary toxin either is a marker for more virulent C. difficile strains or contributes directly to strain virulence. Efforts to control C. difficile infection should target all virulent strains irrespective of PCR ribotype.

We aimed to assess the effect of invasive group A streptococcal (GAS) infection and the potential effects of a multivalent GAS vaccine in New Zealand. During January 2005–December 2006, we conducted prospective population-based laboratory surveillance of Auckland residents admitted to all public hospitals with isolation of GAS from normally sterile sites. Using emm typing, we identified 225 persons with confirmed invasive GAS infection (median 53 years of age; range 0–97 years). Overall incidence was 8.1 cases per 100,00 persons per year (20.4/100,000/year for Maori and Pacific Islanders; 24.4/100,000/year for persons >65 years of age; 33/100,000/year for infants <1 year of age). Nearly half (49%) of all cases occurred in Auckland’s lowest socioeconomic quintile. Twenty-two persons died, for an overall case-fatality rate of 10% (63% for toxic shock syndrome). Seventy-four percent of patients who died had an underlying condition. To the population in our study, the proposed 26-valent vaccine would provide limited benefit.

The United Kingdom implemented a containment strategy for pandemic (H1N1) 2009 through administering antiviral agents (AVs) to patients and their close contacts. This observational household cohort study describes the effect of AVs on household transmission. We followed 285 confirmed primary cases in 259 households with 761 contacts. At 2 weeks, the confirmed secondary attack rate (SAR) was 8.1% (62/761) and significantly higher in persons <16 years of age than in those >50 years of age (18.9% vs. 1.2%, p<0.001). Early (<48 hours) treatment of primary case-patients reduced SAR (4.5% vs. 10.6%, p = 0.003). The SAR in child contacts was 33.3% (10/30) when the primary contact was a woman and 2.9% (1/34) when the primary contact was a man (p = 0.010). Of 53 confirmed secondary case-patients, 45 had not received AV prophylaxis. The effectiveness of AV prophylaxis in preventing infection was 92%.

To determine whether frontline health care workers (HCWs) are at greater risk for contracting pandemic (H1N1) 2009 than nonclinical staff, we conducted a study of 231 HCWs and 215 controls. Overall, 79 (17.7%) of 446 had a positive antibody titer by hemagglutination inhibition, with 46 (19.9%) of 231 HCWs and 33 (15.3%) of 215 controls positive (OR 1.37, 95% confidence interval 0.84–2.22). Of 87 participants who provided a second serum sample, 1 showed a 4-fold rise in antibody titer; of 45 patients who had a nose swab sample taken during a respiratory illness, 7 had positive results. Higher numbers of children in a participant’s family and working in an intensive care unit were risk factors for infection; increasing age, working at hospital 2, and wearing gloves were protective factors. This highly exposed group of frontline HCWs was no more likely to contract pandemic (H1N1) 2009 influenza infection than nonclinical staff, which suggests that personal protective measures were adequate in preventing transmission.

Beginning in the 1980s, New Zealand experienced rising annual rates of campylobacteriosis that peaked in 2006. We analyzed notification, hospitalization, and other data to explore the 2007–2008 drop in campylobacteriosis incidence. Source attribution techniques based on genotyping of Campylobacter jejuni isolates from patients and environmental sources were also used to examine the decline. In 2008, the annual campylobacteriosis notification rate was 161.5/100,000 population, representing a 54% decline compared with the average annual rate of 353.8/100,000 for 2002–2006. A similar decline was seen for hospitalizations. Source attribution findings demonstrated a 74% (95% credible interval 49%–94%) reduction in the number of cases attributed to poultry. These reductions coincided with the introduction of a range of voluntary and regulatory interventions to reduce Campylobacter spp. contamination of poultry. The apparent success of these interventions may inform approaches other countries could consider to help control foodborne campylobacteriosis.

Since the outbreaks of highly pathogenic avian influenza (HPAI) subtype H5N1 virus, wild birds have been suspected of transmitting this virus to poultry. On January 23, 2004, the Ministry of Public Health in Thailand informed the World Health Organization of an avian influenza A (H5N1) outbreak. To determine the epidemiology of this viral infection and its relation to poultry outbreaks in Thailand from 2004 through 2007, we investigated how wild birds play a role in transmission. A total of 24,712 serum samples were collected from migratory and resident wild birds. Reverse transcription PCR showed a 0.7% HPAI (H5N1) prevalence. The highest prevalence was observed during January–February 2004 and March–June 2004, predominantly in central Thailand, which harbors most of the country’s poultry flocks. Analysis of the relationship between poultry and wild bird outbreaks was done by using a nonhomogeneous birth and death statistical model. Transmission efficiency among poultry flocks was 1.7× higher in regions with infected wild birds in the given or preceding month. The joint presence of wild birds and poultry is associated with increased spread among poultry flocks.

Little is known about the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in most Pacific Island nations. Relatively high rates of MRSA have been reported in Polynesian people living outside the Pacific Islands. To determine the prevalence and characteristics of MRSA, we assessed wound swabs from 399 persons with skin and soft tissue infection living in Samoa. MRSA was isolated from 9% of study participants; 34 of the 196 S. aureus isolates were MRSA. Five MRSA genotypes were identified; the 3 most common were USA300, the Queensland clone, and a sequence type 1 MRSA strain that shares <85% homology with the sequence type 1 MRSA strain common in the region (WA MRSA-1). The Southwest Pacific MRSA clone was identified but accounted for only 12% of MRSA isolates. The high prevalence of MRSA in Samoa provides impetus for initiatives to improve antimicrobial drug resistance surveillance, infection control, and antimicrobial drug use in Pacific Island nations.

Neurocysticercosis (NCC) is a parasitic infection of the central nervous system caused by Taenia solium larval cysts. Its epidemiology in cysticercosis-nonendemic regions is poorly understood, and the role of public health institutions is unclear. To determine the incidence of NCC and to pilot screening of household contacts for tapeworms, we conducted population-based active surveillance in Oregon. We screened for T. solium infection by examining hospital billing codes and medical charts for NCC diagnosed during January 1, 2006–December 31, 2009 and collecting fecal and blood samples from household contacts of recent case-patients. We identified 87 case-patients, for an annual incidence of 0.5 cases per 100,000 general population and 5.8 cases per 100,000 Hispanics. In 22 households, we confirmed 2 additional NCC case-patients but no current adult intestinal tapeworm infections. NCC is of clinical and public health concern in Oregon, particularly among Hispanics. Public health intervention should focus on family members because household investigations can identify additional case-patients.

Resistance to extended-spectrum cephalosporins complicates treatment of Pseudomonas aeruginosa infections. To elucidate risk factors for cefepime-resistant P. aeruginosa and determine its association with patient death, we conducted a case–control study in Philadelphia, Pennsylvania. Among 2,529 patients hospitalized during 2001–2006, a total of 213 (8.4%) had cefepime-resistant P. aeruginosa infection. Independent risk factors were prior use of an extended-spectrum cephalosphorin (p<0.001), prior use of an extended-spectrum penicillin (p = 0.005), prior use of a quinolone (p<0.001), and transfer from an outside facility (p = 0.01). Among those hospitalized at least 30 days, mortality rates were higher for those with cefepime-resistant than with cefepime-susceptible P. aeruginosa infection (20.2% vs. 13.2%, p = 0.007). Cefepime-resistant P. aeruginosa was an independent risk factor for death only for patients for whom it could be isolated from blood (p = 0.001). Strategies to counter its emergence should focus on optimizing use of antipseudomonal drugs.

¹Current affiliation: Duke University School of Medicine, Durham, North Carolina, USA.

June 2011 marks the 30th anniversary of the first description of what became known as HIV/AIDS, now one of history’s worst pandemics. The basic public health tools of surveillance and epidemiologic investigation helped define the epidemic and led to initial prevention recommendations. Features of the epidemic, including the zoonotic origin of HIV and its spread through global travel, are central to the concept of emerging infectious diseases. As the epidemic expanded into developing countries, new models of global health and new global partnerships developed. Advocacy groups played a major role in mobilizing the response to the epidemic, having human rights as a central theme. Through the commitments of governments and private donors, modern HIV treatment has become available throughout the developing world. Although the end of the epidemic is not yet in sight and many challenges remain, the response has been remarkable and global health has changed for the better.

Surveillance for influenza virus in pigs in the United Kingdom during spring 2010 detected a novel reassortant influenza virus. This virus had genes encoding internal proteins from pandemic (H1N1) 2009 virus and hemagglutinin and neuraminidase genes from swine influenza virus (H1N2). Our results demonstrate processes contributing to influenza virus heterogeneity.

We analyzed changes in immunologic values over time for 28 hospitalized patients with pandemic (H1N1) 2009. Levels of interleukin-6, interferon-γ, and interleukin-10 increased 1 day after illness onset and then decreased to baseline levels. Levels of virus-specific antibody were undetectable 1 day after illness onset and peaked 36 days later.

Human infection with avian influenza (H5N1) virus raises concern for the possibility of a pandemic. We report 20 cases, which ranged from asymptomatic to fatal, in Pakistan in 2007. These cases indicate human-to-human-to-human transmission of this virus, and the number of cases may be higher than realized.

In China, domestic ducks and wild birds often share the same water, in which influenza viruses replicate preferentially. Isolation of 2 novel reassortant highly pathogenic avian influenza (H5N5) viruses from apparently healthy domestic ducks highlights the role of these ducks as reassortment vessels. Such new subtypes of influenza viruses may pose a pandemic threat.

In February 2006, a patient colonized with a multidrug-resistant sequence type 56 Acinetobacter baumannii strain was admitted to a hospital in Madrid, Spain. This strain spread rapidly and caused a large outbreak in the hospital. Clinicians should be alert for this strain because its spread would have serious health consequences.

The Internet is a common source of medical information and has created novel surveillance opportunities. We assessed the potential for Internet-based surveillance of methicillin-resistant Staphylococcus aureus and examined the extent to which it reflects trends in hospitalizations and news coverage. Google queries were a useful predictor of hospitalizations for methicillin-resistant S. aureus infections.

We conducted a serologic investigation of porcine reproductive and respiratory syndrome virus (PRRSV) in hybrid wild boar herds in China during 2008–2009. PRRSV isolates with novel genetic markers were recovered. Experimental infection of pigs indicated that hybrid wild boars are involved in the epidemiology of PRRSV.

We screened 735 HIV-infected patients in Switzerland with unexplained alanine aminotransferase elevation for hepatitis E virus (HEV) immunoglobulin G. Although HEV seroprevalence in this population is low (2.6%), HEV RNA can persist in patients with low CD4 cell counts. Findings suggest chronic HEV infection should be considered as a cause of persistent alanine aminotransferase elevation.

Macrolide resistance in Mycoplasma pneumoniae is often found in Asia but is rare elsewhere. We report the emergence of macrolide-resistant M. pneumoniae in Israel and the in vivo evolution of such resistance during the treatment of a 6-year-old boy with pneumonia.

To estimate failure rates after treatment with benzathine penicillin and to identify determinants of failure that affected outcomes for yaws, we conducted a cohort study of 138 patients; treatment failed in 24 (17.4%). Having low initial titers on Venereal Disease Research Laboratory test and living in a village where yaws baseline incidence was high were associated with increased likelihood of treatment failure.

In Taiwan, despite a substantial decline of Salmonella enterica serotype Choleraesuis infections, strains resistant to ciprofloxacin and ceftriaxone persist. A self-transferable bla_CMY-2-harboring IncI1 plasmid was identified in S. enterica serotypes Choleraesuis, Typhimurium, Agona, and Enteritidis and contributed to the overall increase of ceftriaxone resistance in salmonellae.

We report Salmonella enterica serotype Typhi strains with a nonclassical quinolone resistance phenotype (i.e., decreased susceptibility to ciprofloxacin but with susceptibility to nalidixic acid) associated with a nonsynonymous mutation at codon 464 of the gyrB gene. These strains, not detected by the nalidixic acid disk screening test, can result in fluoroquinolone treatment failure.

We report 9 ciprofloxacin-resistant Salmonella enterica serotype Typhi isolates submitted to the US National Antimicrobial Resistance Monitoring System during 1999–2008. The first 2 had indistinguishable pulsed-field gel electrophoresis patterns and identical gyrA and parC mutations. Eight of the 9 patients had traveled to India within 30 days before illness onset.

We conducted a retrospective study of 99 patients with methicillin-suseptible Staphylococcus aureus catheter-related bacteremia in which vancomycin MIC was determined by Etest. High vancomycin MIC (>1.5 μg/mL) was the only independent risk factor for development of complicated bacteremia caused by methicillin-susceptible S. aureus (odds ratio 22.9, 95% confidence interval 6.7–78.1).

Real-time reverse transcription PCR revealed that new St-Valerien–like porcine caliciviruses are prevalent (2.6%–80%; 23.8% overall) in finisher pigs in North Carolina. One strain, NC-WGP93C, shares 89.3%–89.7% genomic nucleotide identity with Canadian strains. Whether these viruses cause disease in pigs or humans or are of food safety concern requires further investigation.

Of 176 invasive Streptococcus pneumoniae isolates from children in Malawi, common serotypes were 1 (23%), 6A/B (18%), 14 (6%), and 23F (6%). Coverage with the 7-valent pneumococcal conjugate vaccine (PCV) was 39%; PCV10 and PCV13 increased coverage to 66% and 88%, respectively. We found chloramphenicol resistance in 27% of isolates and penicillin nonsusceptibility in 10% (by using meningitis breakpoints); all were ceftriaxone susceptible.

Listeria monocytogenes is worldwide a pathogen, but the geographic distribution of clones remains largely unknown. Genotyping of 300 isolates from the 5 continents and diverse sources showed the existence of few prevalent and globally distributed clones, some of which include previously described epidemic clones. Cosmopolitan distribution indicates the need for genotyping standardization.

Capsular serotypes of 225 Klebsiella pneumoniae isolates in Taiwan were identified by using PCR. Patients infected with K1 serotypes (41 isolates) had increased community-onset bacteremia, more nonfatal diseases and liver abscesses, lower Pittsburgh bacteremia scores and mortality rates, and fewer urinary tract infections than patients infected with non–K1/K2 serotypes (147 isolates).

To determine if hepatitis C virus seropositivity and active hepatitis B virus infection in HIV-positive patients vary with patients’ geographic origins, we studied co-infections in HIV-seropositive adults. Active hepatitis B infection was more prevalent in persons from Africa, and hepatitis C seropositivity was more common in persons from eastern Europe.

To determine if bovine caliciviruses circulate in France, we studied 456 fecal samples from diarrheic calves. We found a 20% prevalence of genogroup III noroviruses and a predominance of genotype III.2. Neboviruses, with a prevalence of 7%, were all related to the reference strain Bo/Nebraska/80/US, except for the strain Bo/DijonA216/06/FR, which could represent a novel genotype.