Some labile cell types whose numbers are normally controlled through programmed cell death are subject to markedly increased destruction during some severe infections. Lymphocytes, in particular, undergo massive and apparently unregulated apoptosis in human patients and laboratory animals with sepsis, potentially playing a major role in the severe immunosuppression that characterizes the terminal phase of fatal illness. Extensive lymphocyte apoptosis has also occurred in humans and animals infected with several exotic agents, including Bacillus anthracis, the cause of anthrax; Yersinia pestis, the cause of plague; and Ebola virus. Prevention of lymphocyte apoptosis, through either genetic modification of the host or treatment with specific inhibitors, markedly improves survival in murine sepsis models. These findings suggest that interventions aimed at reducing the extent of immune cell apoptosis could improve outcomes for a variety of severe human infections, including those caused by emerging pathogens and bioterrorism agents.

The pyrethroid knockdown resistance gene (kdr) has become widespread in Anopheles gambiae in West Africa. A trial to test the continuing efficacy of insecticide-treated nets (ITN) and indoor residual spraying (IRS) was undertaken in experimental huts at 2 sites in Benin, 1 where kdr is present at high frequency (Ladji), the other where An. gambiae is susceptible (Malanville). Holes were made in the nets to mimic worn nets. At Malanville, 96% of susceptible An. gambiae were inhibited from blood-feeding, whereas at Ladji feeding was uninhibited by ITNs. The mortality rate of An. gambiae in ITN huts was 98% in Malanville but only 30% at Ladji. The efficacy of IRS was equally compromised. Mosquitoes at Ladji had higher oxidase and esterase activity than a laboratory-susceptible strain, but this fact did not seem to contribute to resistance. Pyrethroid resistance in An. gambiae appears to threaten the future of ITN and IRS in Benin.

With the spread of avian influenza, use of automated data streams to rapidly detect and track human influenza cases has increased. We performed correlation analyses to determine whether International Classification of Diseases, Ninth Revision (ICD-9), groupings used to detect influenzalike illness (ILI) within an automated syndromic system correlate with respiratory virus laboratory test results in the same population (r = 0.71 or 0.86, depending on group). We used temporal and signal-to-noise analysis to identify 2 subsets of ICD-9 codes that most accurately represent ILI trends, compared nationwide sentinel ILI surveillance data from the Centers for Disease Control and Prevention with the automated data (r = 0.97), and found the most sensitive set of ICD-9 codes for respiratory illness surveillance. Our results demonstrate a method for selecting the best group of ICD-9 codes to assist system developers and health officials who are interpreting similar data for daily public health activities.

We evaluated the epidemiologic factors of patients seeking treatment for travel-associated illness from January 2004 through May 2005 at the University Hospital of Zurich. When comparing persons whose purpose of travel was visiting friends and relatives (VFR travelers; n = 121) with tourists and other travelers (n = 217), VFR travelers showed a distinct infectious disease and risk spectrum. VFR travelers were more likely to receive a diagnosis of malaria (adjusted odds ratio [OR] = 2.9, 95% confidence interval [CI] 1.2–7.3) or viral hepatitis (OR = 3.1, 95% CI 1.1–9) compared with other travelers but were less likely to seek pre-travel advice (20% vs. 67%, p = 0.0001). However, proportionate rates of acute diarrhea were lower in VFR (173 vs. 364 per 1,000 ill returnees). Travel to sub-Saharan Africa contributed most to malaria in VFR travelers. In countries with large migrant populations, improved public health strategies are needed to reach VFR travelers.

Group B streptococci (GBS) are a recently identified cause of neonatal sepsis in Malawi. In Queen Elizabeth Central Hospital, Blantyre, Malawi, during May 2004–June 2005, GBS were isolated from routine blood and cerebrospinal fluid cultures from 57 infants. The incidence of early (EOD) and late onset (LOD) invasive GBS disease was 0.92 and 0.89 cases per 1,000 live births, respectively. Sepsis (52%) was the most common manifestation of EOD; meningitis (43%) and sepsis (36%) were the principal manifestations of LOD. The case-fatality rate was 33% overall (38% EOD, 29% LOD). Serotypes Ia and III were responsible for 77% of disease. All isolates were susceptible to penicillin, but 21% were resistant to erythromycin. The rate and manifestations of neonatal GBS disease in Malawi are similar to those in industrialized countries, but the case-fatality rate is higher than in industrialized countries. Effective locally relevant prevention strategies are needed.

Cysticercosis has emerged as a cause of severe neurologic disease in the United States. We evaluated cysticercosis-related deaths in the United States for 1990–2002 by race, sex, age, state of residence, country of birth, and year of death. A total of 221 cysticercosis deaths were identified. Mortality rates were highest for Latinos (adjusted rate ratio [ARR] 94.5, relative to whites) and men (ARR = 1.8). The mean age at death was 40.5 years (range 2–88). Most patients (187 [84.6%]) were foreign born, and 137 (62%) had emigrated from Mexico. The 33 US-born persons who died of cysticercosis represented 15% of all cysticercosis-related deaths. The cysticercosis mortality rate was highest in California, which accounted for ≈60% of all deaths. Although uncommon, cysticercosis is a cause of premature death in the United States. Fatal cysticercosis affected mainly immigrants from Mexico and other Latin American countries; however, US-born persons were also affected.

We noted a marked increase in healthcare-associated (HA) methicillin-resistant Staphylococcus aureus (MRSA) infections caused by isolates phenotypically consistent with community-associated (CA)-MRSA strains. To study this trend, we retrospectively examined all HA-MRSA isolates from patients in our institution during 1999–2004. An isolate was considered an SCCmecIV phenotype if it had antimicrobial drug susceptibilities consistent with typical CA-MRSA isolates. Our phenotypic definition was validated in a limited subset of isolates by SCCmec genotype, pulsed-field gel electrophoresis, and multilocus sequence typing. Among 352 patients with HA-MRSA isolates, SCCmecIV phenotype increased from 17% in 1999 to 56% in 2003 (p<0.0001). Antimicrobial drug-susceptibility phenotype and genotype were consistent in 21 (91%) of 23 isolates. In a multivariate model, the SCCmec type IV phenotype was independently associated with wound culture source, later year of collection, and MRSA isolated earlier during hospitalization. In conclusion, MRSA isolates phenotypically similar to CA strains have become the predominant isolates associated with HA-MRSA in our hospital.

Avian influenza A virus subtype H5N1 was transmitted to domestic cats by close contact with infected birds. Virus-specific nucleic acids were detected in pharyngeal swabs from 3 of 40 randomly sampled cats from a group of 194 animals (day 8 after contact with an infected swan). All cats were transferred to a quarantine station and monitored for clinical signs, virus shedding, and antibody production until day 50. Despite unfamiliar handling, social distress and the presence of other viral and nonviral pathogens that caused illness and poor health and compromised the immune systems, none of the cats developed clinical signs of influenza. There was no evidence of horizontal transmission to other cats because only 2 cats developed antibodies against H5N1 virus.

According to the World Health Organization, human African trypanosomiasis (HAT) (sleeping sickness) caused the loss of ≈1.5 million disability-adjusted life years (DALYs) in 2002. We describe the effect of HAT during 2000–2002 in Buma, a rural community near Kinshasa in the Democratic Republic of Congo. We used retrospective questionnaire surveys to estimate HAT-related household costs and DALYs. The HAT outbreak in Buma involved 57 patients and affected 47 (21%) households. The cost to each household was equivalent to 5 months’ income for that household. The total number of HAT-related DALYs was 2,145, and interventions to control HAT averted 1,408 DALYs. The cost per DALY averted was US $17. Because HAT has a serious economic effect on households and control interventions are cost-effective, considering only global burden of disease rankings for resource allocation could lead to misguided priority setting if applied without caution in HAT-affected countries.

We describe isolates from human Campylobacter infection in the French population and the isolates' antimicrobial drug resistance patterns since 1986 and compare the trends with those of isolates from broiler chickens and pigs from 1999 to 2004. Among 5,685 human Campylobacter isolates, 76.2% were C. jejuni, 17.2% C. coli, and 5.0% C. fetus. Resistance to nalidixic acid increased from 8.2% in 1990 to 26.3% in 2004 (p<10^-3), and resistance to ampicillin was high over time. Nalidixic acid resistance was greater for C. coli (21.3%) than for C. jejuni (14.9%, p<10^-3). C. jejuni resistance to ciprofloxacin in broilers decreased from 31.7% in 2002 to 9.0% in 2004 (p = 0.02). The patterns of resistance to quinolones and fluoroquinolones were similar between 1999 and 2004 in human and broiler isolates for C. jejuni. These results suggest a potential benefit of a regulation policy limiting use of antimicrobial drugs in food animals.

Establishing sources of human infection supports effective disease control measures. Host association with Campylobacter jejuni was analyzed by using multilocus sequence typing data for 713 isolates from chickens and bovids (cattle and sheep). Commonly used summary measures of genotypes (sequence type and clonal complex) showed poor accuracy, but a method using the full allelic profile showed 80% accuracy in distinguishing isolates from these 2 host groups. We explored the biologic basis of more accurate results with allelic profiles. Strains isolated from specific hosts have imported a substantial number of alleles while circulating in those host species. These results imply that 1) although Campylobacter moves frequently between hosts, most transmission is within species, and 2) lineages can acquire a host signature and potentially adapt to the host through recombination. Assignment using this signature enables improved prediction of source for pathogens that undergo frequent genetic recombination.

We describe the epidemiology of invasive meningococcal disease in South Africa from August 1999 through July 2002, as reported to a laboratory-based surveillance system. Neisseria meningitidis isolates were further characterized. In total, 854 cases of laboratory-confirmed disease were reported, with an annual incidence rate of 0.64/100,000 population. Incidence was highest in infants <1 year of age. Serogroup B caused 41% of cases; serogroup A, 23%; serogroup Y, 21%; serogroup C, 8%; and serogroup W135, 5%. Serogroup B was the predominant serogroup in Western Cape Province, and disease rates remained stable. Serogroup A was most prevalent in Gauteng Province and increased over the 3 years. On pulsed-field gel electrophoresis analysis, serogroup A strains showed clonality, and serogroup B demonstrated considerable diversity. Selected isolates of serogroup A belonged to sequence type (ST)-1 (subgroup I/II) complex, serogroup B to ST-32/electrophoretic type (ET)-5 complex, and serogroup W135 to ST-11/ET-37 complex.

Severity of disease is markedly increased when infection with dengue virus type 2 (DENV-2) follows infection with DENV-1. Studies have shown that heterologous neutralizing antibody titers are inversely correlated with severity of a second infection. If this mechanism controlled disease severity in Cuba, heterotypic antibody titers should have declined over time. To determine whether phenotypic changes in dengue antibodies occur over time, we analyzed serum samples collected 4–8 and 20–22 years after DENV-1 infection. We found a significant increase in mean titer of homologous DENV-1 neutralizing antibodies and a significant decrease in heterologous antibodies to 1 of 2 genotypes of DENV-2 virus (the American genotype). Asian DENV-2 viruses were not neutralized during either interval; however, the American genotype underwent phenotypic changes in heterotypic viral neutralizing antibodies in the predicted direction. This finding may be related to the time-dependent changes in severity of disease found with secondary dengue infection.

Methicillin-resistant Staphylococcus aureus of clonal lineage ST398 that exhibits related spa types and contains SCCmec elements of types IVa or V has been isolated from colonized and infected humans and companion animals (e.g., dog, pig, horse) in Germany and Austria. Of particular concern is the association of these cases with cases of nosocomial ventilator-associated pneumonia.

Two waterborne outbreaks of toxoplasmosis have been described recently in southern Brazil. We present data from a community-based study of pregnant women in northeastern Brazil. Consumption of homemade ice was the only variable associated with seropositivity (adjusted odds ratio, 3.1, 95% confidence interval, 1.53–6.24). Our results suggest water as a source of infection with Toxoplasma gondii.

During autumn 2005, we conducted 3,436 interviews in European and Asian countries. We found risk perceptions of avian influenza to be at an intermediate level and beliefs of efficacy to be slightly lower. Risk perceptions were higher in Asia than Europe; efficacy beliefs were lower in Europe than Asia.

We reviewed reports to the Centers for Disease Control and Prevention of US travelers suspected of having avian influenza A H5N1 virus infection from February 2003 through May 2006. Among the 59 reported patients, no evidence of H5N1 virus infection was found; none had had direct contact with poultry, but 42% had evidence of human influenza A.

This single-center, case-control study documents a relative increase in methicillin resistance among 48 cases of Staphylococcus aureus–associated postpartum mastitis during 1998–2005. Of 21 cases with methicillin resistance, 17 (81%) occurred in 2005. Twenty (95%) isolates contained the Staphylococcus cassette chromosome mec type IV gene; this suggests that the increase is due to community-acquired methicillin-resistant Staphylococcus aureus.

Disseminated neonatal herpes simplex virus (HSV) infection is characterized by progressive multiple organ failure and high mortality rates. It can result from infection with either HSV-1 or HSV-2. We report a case of disseminated neonatal herpes that was caused by HSV-1 and HSV-2.

In 2005, 13.5% of clinic-admitted raptors in northern Colorado tested positive for West Nile virus (WNV). Clinic-admitted–raptor surveillance detected WNV activity nearly 14 weeks earlier than other surveillance systems. WNV surveillance using live raptor admissions to rehabilitation clinics may offer a novel surveillance method and should be considered along with other techniques already in use.

After Hurricane Jeanne in September 2004, surveillance for mosquitoborne diseases in Gonaïves, Haiti, identified 3 patients with malaria, 2 with acute dengue infections, and 2 with acute West Nile virus infections among 116 febrile patients. These are the first reported human West Nile virus infections on the island of Hispaniola.

Invasive and skin community-associated (CA)–methicillin-resistant Staphylococcus aureus (MRSA) isolates from children were matched with invasive CA–methicillin-sensitive S. aureus strains during 2000–2004. Isolates were analyzed for presence of Panton-Valentine leukocidin. A USA400 lineage clone (n = 6) and the predominant USA300 lineage clone emerged.

An ertapenem-resistant Escherichia coli isolate was recovered from peritoneal fluid in a patient who had been treated with imipenem/cilastatin for 10 days. Ertapenem resistance may be explained by a defect in the outer membrane protein and production of extended-spectrum β-lactamase CTX-M-2.

A surveillance system used different detection methods to estimate prevalence of Shiga toxin–producing Escherichia coli during 2003–2005 and 2001–2002. More non-O157 serotypes were detected by enzyme immunoassay than by evaluation of non-sorbitol–fermenting E. coli isolates. We therefore recommend use of enzyme immunoassay and culture-based methods.

We developed a system for rapid determination of viral RNA sequences whereby genomic sequence is obtained from cultured virus isolates without subcloning into plasmid vectors. This method affords new opportunities to address the challenges of unknown or untypeable emerging viruses.

In a prospective study of 660 HIV-positive Malawian adults, we diagnosed Pneumocystis jirovecii pneumonia (PcP) using clinical features, induced sputum for immunofluorescent staining, real-time PCR, and posttreatment follow-up. PcP incidence was highest in patients with the lowest CD4 counts but uncommon compared with incidences of pulmonary tuberculosis and bacterial pneumonia.

Infection with environmental mycobacteria is increasing among many Chesapeake Bay fish species. Prevalence in juvenile Atlantic menhaden differed between tributaries and ranged from 2% to 57%. Mycobacterial infection may be a syndromic sentinel of altered environmental conditions that threaten aquatic animal health.

Yersinia pestis DNA was recently detected in human remains from 2 ancient plague pandemics in France and Germany. We have now sequenced Y. pestis glpD gene in such remains, showing a 93-bp deletion specific for biotype Orientalis. These data show that only Orientalis type caused the 3 plague pandemics.

We describe a man with a febrile illness and an eschar that developed at the site of a tick bite. Rickettsia parkeri was detected and isolated from the eschar. This report represents the second documented case of R. parkeri rickettsiosis in a US serviceman in eastern Virginia.