Attrition, physical integrity and insecticidal activity of long-lasting insecticidal nets in sub-Saharan Africa and modelling of their impact on vectorial capacity.

BACKGROUND: Long-lasting insecticidal nets (LLINs) are the primary malaria prevention and control intervention in many parts of sub-Saharan Africa. While LLINs are expected to last at least 3 years under normal use conditions, they can lose effectiveness because they fall out of use, are discarded, repurposed, physically damaged, or lose insecticidal activity. The contributions of these different interrelated factors to durability of nets and their protection against malaria have been unclear. METHODS: Starting in 2009, LLIN durability studies were conducted in seven countries in Africa over 5 years. WHO-recommended measures of attrition, LLIN use, insecticidal activity, and physical integrity were recorded for eight different net brands. These data were combined with analyses of experimental hut data on feeding inhibition and killing effects of LLINs on both susceptible and pyrethroid resistant malaria vectors to estimate the protection against malaria transmission-in terms of vectorial capacity (VC)-provided by each net cohort over time. Impact on VC was then compared in hypothetical scenarios where one durability outcome measure was set at the best possible level while keeping the others at the observed levels. RESULTS: There was more variability in decay of protection over time by country than by net brand for three measures of durability (ratios of variance components 4.6, 4.4, and 1.8 times for LLIN survival, use, and integrity, respectively). In some countries, LLIN attrition was slow, but use declined rapidly. Non-use of LLINs generally had more effect on LLIN impact on VC than did attrition, hole formation, or insecticide loss. CONCLUSIONS: There is much more variation in LLIN durability among countries than among net brands. Low levels of use may have a larger impact on effectiveness than does variation in attrition or LLIN degradation. The estimated entomological effects of chemical decay are relatively small, with physical decay probably more important as a driver of attrition and non-use than as a direct cause of loss of effect. Efforts to maximize LLIN impact in operational settings should focus on increasing LLIN usage, including through improvements in LLIN physical integrity. Further research is needed to understand household decisions related to LLIN use, including the influence of net durability and the presence of other nets in the household.

The Public Health Legacy of Polio Eradication in Africa.

The legacy of polio in Africa goes far beyond the tragedies of millions of children with permanent paralysis. It has a positive side, which includes the many well-trained polio staff who have vaccinated children, conducted surveillance, tested stool specimens in the laboratories, engaged with communities, and taken care of polio patients. This legacy also includes support for routine immunization services and vaccine introductions and campaigns for other diseases. As polio funding declines, it is time to take stock of the resources made available with polio funding in Africa and begin to find ways to keep some of the talented staff, infrastructure, and systems in place to work on new public health challenges. The partnerships that helped support polio eradication will need to consider funding to maintain and to strengthen routine immunization services and other maternal, neonatal, and child health programs in Africa that have benefitted from the polio eradication infrastructure.

Role of Food Insecurity in Outbreak of Anthrax Infections among Humans and Hippopotamuses Living in a Game Reserve Area, Rural Zambia.

In September 2011, a total of 511 human cases of anthrax (Bacillus anthracis) infection and 5 deaths were reported in a game management area in the district of Chama, Zambia, near where 85 hippopotamuses (Hippopotamus amphibious) had recently died of suspected anthrax. The human infections generally responded to antibiotics. To clarify transmission, we conducted a cross-sectional, interviewer-administered household survey in villages where human anthrax cases and hippopotamuses deaths were reported. Among 284 respondents, 84% ate hippopotamus meat before the outbreak. Eating, carrying, and preparing meat were associated with anthrax infection. Despite the risk, 23% of respondents reported they would eat meat from hippopotamuses found dead again because of food shortage (73%), lack of meat (12%), hunger (7%), and protein shortage (5%). Chronic food insecurity can lead to consumption of unsafe foods, leaving communities susceptible to zoonotic infection. Interagency cooperation is necessary to prevent outbreaks by addressing the root cause of exposure, such as food insecurity.

A longitudinal study of the durability of long-lasting insecticidal nets in Zambia.

BACKGROUND: A key goal of malaria control is to achieve universal access to, and use of, long-lasting insecticidal nets (LLINs) among people at risk for malaria. Quantifying the number of LLINs needed to achieve and maintain universal coverage requires knowing when nets need replacement. Longitudinal studies have observed physical deterioration in LLINs well before the assumed net lifespan of 3 years. The objective of this study was to describe attrition, physical integrity and insecticide persistence of LLINs over time to assist with better quantification of nets needing replacement. METHODS: 999 LLINs distributed in 2011 in two highly endemic provinces in Zambia were randomly selected, and were enrolled at 12 months old. LLINs were followed every 6 months up to 30 months of age. Holes were counted and measured (finger, fist, and head method) and a proportional hole index (pHI) was calculated. Households were surveyed about net care and repair and if applicable, reasons for attrition. Functional survival was defined as nets with a pHI <643 and present for follow-up. At 12 and 24 months of age, 74 LLINs were randomly selected for examination of insecticidal activity and content using bioassay and chemical analysis methods previously described by the World Health Organization (WHO). RESULTS: A total of 999 LLINs were enrolled; 505 deltamethrin-treated polyester nets and 494 permethrin-treated polyethylene nets. With 74 used to examine insecticide activity, 925 were available for full follow-up. At 30 months, 325 (33 %) LLINs remained. Net attrition was primarily due to disposal (29 %). Presence of repairs and use over a reed mat were significantly associated with larger pHIs. By 30 months, only 56 % of remaining nets met criteria for functional survival. A shorter functional survival was associated with having been washed. At 24 months, nets had reduced insecticidal activity (57 % met WHO minimal criteria) and content (5 % met WHO target insecticide content). CONCLUSIONS: The median functional survival time for LLINs observed the study was 2.5-3 years and insecticide activity and content were markedly decreased by 2 years. A better measure of net survival incorporating insecticidal field effectiveness, net physical integrity, and attrition is needed.

Malaria surveillance in low-transmission areas of Zambia using reactive case detection.

BACKGROUND: Repeat national household surveys suggest highly variable malaria transmission and increasing coverage of high-impact malaria interventions throughout Zambia. Many areas of very low malaria transmission, especially across southern and central regions, are driving efforts towards sub-national elimination. CASE DESCRIPTION: Reactive case detection (RCD) is conducted in Southern Province and urban areas of Lusaka in connection with confirmed incident malaria cases presenting to a community health worker (CHW) or clinic and suspected of being the result of local transmission. CHWs travel to the household of the incident malaria case and screen individuals living in adjacent houses in urban Lusaka and within 140 m in Southern Province for malaria infection using a rapid diagnostic test, treating those testing positive with artemether-lumefantrine. DISCUSSION: Reactive case detection improves access to health care and increases the capacity for the health system to identify malaria infections. The system is useful for targeting malaria interventions, and was instrumental for guiding focal indoor residual spraying in Lusaka during the 2014/2015 spray season. Variations to maximize impact of the current RCD protocol are being considered, including the use of anti-malarials with a longer lasting, post-treatment prophylaxis. CONCLUSION: The RCD system in Zambia is one example of a malaria elimination surveillance system which has increased access to health care within rural communities while leveraging community members to build malaria surveillance capacity.

Long-lasting insecticidal nets in Zambia: a cross-sectional analysis of net integrity and insecticide content.

BACKGROUND: Long-lasting insecticidal nets (LLINs) are a mainstay of malaria prevention in Africa. More LLINs are available now than in any time previously due to increases in funding for malaria control. LLINs are expected to last three to five years before they need to be replaced. Reports of nets lasting less than three years are frequent in Zambia, which, if true, will increase the number of LLINs needed to maintain universal coverage. METHODS: This study collected nets distributed during mass distribution campaigns. One net was collected from each participating home in 12 districts in 2010 and all nets were examined for holes. One household member was surveyed about net use and care. RESULTS: The study collected 713 polyester nets with a median age of 31 months (range 27-44 months, interquartile (IQR) range: 29-36 months), median number of holes was 17 (IQR: 5-33), and median total hole size was 88.3 sq cm (IQR: 14.5-360.4). The median total number of holes did differ by age of the net, from 27-44 months, but not in a linear fashion. The difference in the number of holes in the newest and oldest nets was not statistically significant. The mean deltamethrin level for all nets was 23 mg/sq m (≥8 mg/sq m is considered effective). There was a larger total hole area in the lower half of the nets (repeat measures ANOVA, F=228.43, df=2, p<0.0001) compared to the upper half and roof of the net. Only 8.7% of nets had evidence of repairs. CONCLUSIONS: At 27-30 months, LLINs already had a large total hole surface area that was equivalent to the oldest nets observed. Nets were often tucked under reed mats which may explain the finding that the largest hole area was found in the lower half of the net. Studies need to be conducted prospectively to determine when physical deterioration occurs and why nets are discarded. Re-enforcing the lower half of the sides of LLINs may help decrease holes.

Enhanced surveillance and data feedback loop associated with improved malaria data in Lusaka, Zambia.

BACKGROUND: Accurate and timely malaria data are crucial to monitor the progress towards and attainment of elimination. Lusaka, the capital city of Zambia, has reported very low malaria prevalence in Malaria Indicator Surveys. Issues of low malaria testing rates, high numbers of unconfirmed malaria cases and over consumption of anti-malarials were common at clinics within Lusaka, however. The Government of Zambia (GRZ) and its partners sought to address these issues through an enhanced surveillance and feedback programme at clinic level. METHODS: The enhanced malaria surveillance programme began in 2011 to verify trends in reported malaria, as well as to implement a data feedback loop to improve data uptake, use, and quality. A process of monthly data collection and provision of feedback was implemented within all GRZ health clinics in Lusaka District. During clinic visits, clinic registers were accessed to record the number of reported malaria cases, malaria test positivity rate, malaria testing rate, and proportion of total suspected malaria that was confirmed with a diagnostic test. RESULTS AND DISCUSSION: Following the enhanced surveillance programme, the odds of receiving a diagnostic test for a suspected malaria case increased (OR = 1.54, 95 % CI = 0.96-2.49) followed by an upward monthly trend (OR = 1.05, 95 % CI = 1.01-1.09). The odds of a reported malaria case being diagnostically confirmed also increased monthly (1.09, 95 % CI 1.04-1.15). After an initial 140 % increase (95 % CI = 91-183 %), costs fell by 11 % each month (95 % CI = 5.7-10.9 %). Although the mean testing rate increased from 18.9 to 64.4 % over the time period, the proportion of reported malaria unconfirmed by diagnostic remained high at 76 %. CONCLUSIONS: Enhanced surveillance and implementation of a data feedback loop have substantially increased malaria testing rates and decreased the number of unconfirmed malaria cases and courses of ACT consumed in Lusaka District within just two years. Continued support of enhanced surveillance in Lusaka as well as national scale-up of the system is recommended to reinforce good case management and to ensure timely, reliable data are available to guide targeting of limited malaria prevention and control resources in Zambia.

Progress toward polio eradication - worldwide, 2014-2015.

In 1988, the World Health Assembly of the World Health Organization (WHO) resolved to eradicate polio worldwide. Wild poliovirus (WPV) transmission has been interrupted in all but three countries (Afghanistan, Nigeria, and Pakistan). No WPV type 2 cases have been detected worldwide since 1999, and the last WPV type 3 case was detected in Nigeria in November 2012; since 2012, only WPV type 1 has been detected. Circulating vaccine-derived poliovirus (cVDPV), usually type 2, continues to cause cases of paralytic polio in communities with low population immunity. In 2012, the World Health Assembly declared global polio eradication "a programmatic emergency for global public health", and in 2014, WHO declared the international spread of WPV to previously polio-free countries to be "a public health emergency of international concern". This report summarizes global progress toward polio eradication during 2014-2015 and updates previous reports. In 2014, a total of 359 WPV cases were reported in nine countries worldwide. Although reported WPV cases increased in Pakistan and Afghanistan, cases in Nigeria decreased substantially in 2014, and encouraging progress toward global WPV transmission interruption has occurred. Overcoming ongoing challenges to interruption of WPV transmission globally will require sustained programmatic enhancements, including improving the quality of supplementary immunization activities (SIAs) to interrupt transmission in Afghanistan and Pakistan and to prevent WPV exportation to polio-free countries.

Evaluation of sulphadoxine-pyrimethamine for intermittent preventive treatment of malaria in pregnancy: a retrospective birth outcomes study in Mansa, Zambia.

BACKGROUND: Intermittent preventive treatment of malaria in pregnancy (IPTp) with sulphadoxine-pyrimethamine (SP) decreases placental parasitaemia, thus improving birth outcomes. Zambian policy recommends monthly SP-IPTp doses given presumptively during pregnancy at each antenatal examination, spaced one month apart after 16 weeks of gestation. The effectiveness of SP-IPTp was evaluated in Zambia where a recent study showed moderate prevalence of Plasmodium falciparum parasites with genetic mutations that confer SP resistance. METHODS: HIV-negative women were enrolled at the time of delivery at two facilities in Mansa, Zambia, an area of high malaria transmission. Women were interviewed and SP exposure was determined by antenatal card documentation or self-reports. Using Poisson regression modelling, the effectiveness of SP-IPTp was evaluated for outcomes of parasitaemia (microscopic examination of maternal peripheral, cord, and placental blood films), maternal anaemia (Hb < 11 g/dl), placental infection (histopathology), and infant outcomes (low birth weight (LBW), preterm delivery, and small for gestational age) in women who took 0-4 doses of SP-IPTp. RESULTS: Participants included 435 women, with a median age of 23 years (range 16-44). Thirty-four women took zero doses of SP-IPTp, while 115, 142 and 144 women took one, two, or ≥ three doses, respectively. Multivariate Poisson regression models considering age, mosquito net usage, indoor residual spraying, urban home, gravidity, facility, wet season delivery, and marital status showed that among paucigravid women ≥ two doses of SP-ITPp compared to one or less doses was associated with a protective effect on LBW (prevalence ratio (PR) 0.33, 95% confidence interval (CI) 0.12-0.91) and any infection (PR 0.76, CI 0.58-0.99). Multivariate models considering SP-IPTp as a continuous variable showed a protective dose-response association with LBW (paucigravid women: PR 0.54, CI 0.33-0.90, multigravid women: PR 0.63, CI 0.41-0.97). CONCLUSIONS: In Mansa, Zambia, an area of moderate SP resistance, ≥ two doses of SP-IPTp were associated with a protective effect from malaria in pregnancy, especially among paucigravid women. Each dose of SP-IPTp contributed to a 46 and 37% decrease in the frequency of LBW among paucigravid and multigravid women, respectively. SP-IPTp remains a viable strategy in this context.

Association between malaria control and paediatric blood transfusions in rural Zambia: an interrupted time-series analysis.

BACKGROUND: Blood transfusions can reduce mortality among children with severe malarial anaemia, but there is limited evidence quantifying the relationship between paediatric malaria and blood transfusions. This study explores the extent to which the use of paediatric blood transfusions is affected by the number of paediatric malaria visits and admissions. It assesses whether the scale-up of malaria control interventions in a facility catchment area explains the use of paediatric blood transfusions. METHODS: The study was conducted at a referral hospital for 13 rural health centres in rural Zambia. Data were used from facility and patient records covering all paediatric malaria admissions from 2000 to 2008. An interrupted time series analysis using an autoregression-moving-average model was conducted to assess the relationship between paediatric malaria outpatient visits and admissions and the use of paediatric blood transfusions. Further investigation explored whether the use of paediatric blood transfusions over time was consistent with the roll out of malaria control interventions in the hospital catchment area. RESULTS: For each additional paediatric malaria outpatient visit, there were 0.07 additional paediatric blood transfusions (95% CI 0.01-0.13; p < 0.05). For each additional paediatric admission for severe malarial anaemia, there were 1.09 additional paediatric blood transfusions (95% CI 0.95-1.23; p < 0.01). There were 19.1 fewer paediatric blood transfusions per month during the 2004-2006 malaria control period (95% CI 12.1-26.0; p < 0.01), a 50% reduction compared to the preceding period when malaria control was relatively limited. During the 2007-2008 malaria control period, there were 27.5 fewer paediatric blood transfusions per month (95% CI 14.6-40.3; p < 0.01), representing a 72% decline compared to the period with limited malaria control. CONCLUSIONS: Paediatric admissions for severe malarial anaemia largely explain total use of paediatric blood transfusions. The reduction in paediatric blood transfusions is consistent with the timing of the malaria control interventions. Malaria control seems to influence the use of paediatric blood transfusions by reducing the number of paediatric admissions for severe malarial anaemia. Reduced use of blood transfusions could benefit other areas of the health system through greater blood availability, particularly where supply is limited.

Efficacy of sulphadoxine-pyrimethamine for intermittent preventive treatment of malaria in pregnancy, Mansa, Zambia.

BACKGROUND: Intermittent preventive treatment of malaria in pregnancy (IPTp) with sulphadoxine-pyrimethamine (SP) decreases adverse effects of malaria during pregnancy. Zambia implemented its IPTp-SP programme in 2003. Emergence of SP-resistant Plasmodium falciparum threatens this strategy. The quintuple mutant haplotype (substitutions in N51I, C59R, S108N in dhfr and A437G and K540E in dhps genes), is associated with SP treatment failure in non-pregnant patients with malaria. This study examined efficacy of IPTp-SP and presence of the quintuple mutant among pregnant women in Mansa, Zambia. METHODS: In Mansa, an area with high malaria transmission, HIV-negative pregnant women presenting to two antenatal clinics for the 1st dose of IPTp-SP with asymptomatic parasitaemia were enrolled and microscopy for parasitaemia was done weekly for five weeks. Outcomes were parasitological failure and adequate parasitological response (no parasitaemia during follow-up). Polymerase chain reaction assays were employed to distinguish recrudescence from reinfection, and identify molecular markers of SP resistance. Survival analysis included those who had reinfection and incomplete follow-up (missed at least one follow-up). RESULTS: Of the 109 women included in the study, 58 (53%) completed all follow-up, 34 (31%) had incomplete follow-up, and 17 (16%) were lost to follow-up after day 0. Of those who had complete follow-up, 15 (26%, 95% confidence interval [CI] [16-38]) had parasitological failure. For the 92 women included in the survival analysis, median age was 20 years (interquartile range [IQR] 18-22), median gestational age was 22 weeks (IQR range 20-24), and 57% were primigravid. There was no difference in time to failure in primigravid versus multigravid women. Of the 84 women with complete haplotype data for the aforementioned loci of the dhfr and dhps genes, 53 (63%, 95% CI [50-70]) had quintuple mutants (two with an additional mutation in A581G of dhps). Among women with complete follow-up and quintuple mutants, 22% had parasitological failure versus 0% without (p = 0.44). CONCLUSIONS: While underpowered, this study found 26% failure rates of SP given the moderate prevalence of the quintuple mutant haplotype. Despite the presence of resistance, SP retained some efficacy in clearing parasites in pregnant women, and may remain a viable option for IPTp in Zambia.

Child, household, and caregiver characteristics associated with hospitalization for influenza among children 6-59 months of age: an emerging infections program study.

BACKGROUND: Young children are at increased risk of severe outcomes from influenza illness, including hospitalization. We conducted a case-control study to identify risk factors for influenza-associated hospitalizations among children in US Emerging Infections Program sites. METHODS: Cases were children 6-59 months of age hospitalized for laboratory-confirmed influenza infections during 2005-2008. Age- and zip-code-matched controls were enrolled. Data on child, caregiver and household characteristics were collected from parents and medical records. Conditional logistic regression was used to identify independent risk factors for hospitalization. RESULTS: We enrolled 290 (64%) of 454 eligible cases and 1089 (49%) of 2204 eligible controls. Risk for influenza hospitalization increased with maternal age <26 years [odds ratio (OR): 1.8, 95% confidence interval (CI): 1.1-2.9]; household income below the poverty threshold (OR: 2.2, 95% CI: 1.4-3.6); smoking by >50% of household members (OR: 2.9, 95% CI: 1.4-6.6); lack of household influenza vaccination (OR: 1.8, 95% CI: 1.2-2.5) and presence of chronic illnesses, including hematologic/oncologic (OR: 11.8, 95% CI: 4.5-31.0), pulmonary (OR: 2.9, 95% CI: 1.9-4.4) and neurologic (OR: 3.8, 95% CI: 1.6-9.2) conditions. Full influenza immunization decreased the risk among children 6-23 months of age (OR: 0.5, 95% CI: 0.3-0.9) but not among those 24-59 months of age (OR: 1.5, 95% CI: 0.8-3.0; P value for difference = 0.01). CONCLUSIONS: Chronic illnesses, young maternal age, poverty, household smoking and lack of household influenza vaccination increased the risk of influenza hospitalization. These characteristics may help providers to identify young children who are at greatest risk for severe outcomes from influenza illness.

Polio outbreak among nomads in Chad: outbreak response and lessons learned.

BACKGROUND: In response to the 2011 and 2012 polio epidemic in Chad, Chad's Ministry of Public Health, with support from Global Polio Eradication Initiative partners, took steps to increase vaccination coverage of nomadic children with targeted polio campaigns. This article describes the strategies we used to vaccinate nomads in 3 districts of Chad. METHODS: Our targeted interventions involved using mobile vaccination teams, recruiting local nomads to identify settlements, using social mobilization, and offering vaccinations to children, women, and animals. RESULTS: Vaccination coverage of nomadic children 0-59 months of age increased, particularly among those never before vaccinated against polio. These increases occurred mostly in the intervention districts of Dourbali, from 2956 to 8164 vaccinated children, and Kyabe, from 7319 to 15 868. The number of first-time vaccinated nomadic children also increased the most in these districts, from 60 to 131 in Dourbali and from 1302 to 2973 in Kyabe. Coverage in the Massaguet district was only 37.7%. CONCLUSIONS: Our success was probably due to (1) appointment of staff to oversee implementation, (2) engagement of the national government and its partners, (3) participation of nomadic community leaders, (4) intersectoral collaboration between human and animal health services, and (5) flexibility and capacity of vaccinators to vaccinate when and where nomads were available.

Nearly complete elimination of the 7-valent pneumococcal conjugate vaccine serotypes in Tennessee.

BACKGROUND: Invasive pneumococcal disease (IPD) rates decreased after 7-valent pneumococcal conjugate vaccine (PCV) introduction in 2000. We assessed whether previously described decreases were sustained. METHODS: Active laboratory-based surveillance identified IPD cases in 5 Tennessee Counties. For each case, clinical data were collected, and antibiotic susceptibility testing and serotyping were performed. Penicillin resistance was defined as intermediate- or high-level resistance to penicillin. Serotypes were classified as PCV7, PCV13 (6 additional serotypes not in PCV7), pneumococcal polysaccharide vaccine (PPV23, 11 additional serotypes not in PCV13 and nonvaccine serotypes. Total and penicillin-resistant IPD rates were calculated for persons <2, 2-14 and ≥15 years of age before (1998 to 1999) and after (2001 to 2008) PCV7 introduction. RESULTS: Annual IPD rates in children <2 years of age declined by 75% after PCV7 introduction (P < 0.001). Annual IPD rates in children 2-14 years of age declined by 51% after PCV7 introduction (P < 0.001). IPD rates in persons ≥15 of age years initially decreased 40% from 22 to 13 per 100,000 person-years (from 1998 through 2004), and then increased to 18 per 100,000 person-years in 2008. Both IPD and penicillin-resistant IPD PCV7 serotypes were almost completely eliminated in all age groups by 2008. During 2005 to 2008, 52.5%, 58% and 38% of IPD serotypes in children <2, 2-14 and ≥15 years of age, respectively, were the additional 6 serotypes in PCV13. CONCLUSIONS: Overall, 9 years after PCV7 introduction both penicillin-susceptible and resistant IPD rates PCV7 serotypes have been nearly eliminated in Tennessee in all age groups. Total IPD rates remain reduced in children <15 years of age, whereas total IPD rates in persons ≥15 years of age have approached pre-PCV7 rates due to modest increases in nonvaccine serotypes.

Seasonal influenza morbidity estimates obtained from telephone surveys, 2007.

OBJECTIVES: We assessed telephone surveys as a novel surveillance method, comparing data obtained by telephone with existing national influenza surveillance systems, and evaluated the utility of telephone surveys. METHODS: We used the 2007 Behavioral Risk Factor Surveillance System (BRFSS) and the 2007 National Immunization Survey-Adult (NIS-Adult) to estimate the incidence of influenza-like illness (ILI), medically attended ILI, provider-diagnosed influenza, influenza testing, and treatment of influenza with antiviral medications during the 2006-2007 influenza season. RESULTS: With the January-May BRFSS, among persons aged 18 years and older, the cumulative incidence of seasonal ILI and provider-diagnosed influenza was 37.9 and 5.7 adults per 100 persons, respectively. Monthly medically attended ILI and provider-diagnosed influenza among adults were temporally associated with influenza activity, as documented by national surveillance. With the NIS-Adult survey data, estimated provider-diagnosed influenza, influenza testing, and antiviral treatment were 2.8%, 1.4%, and 0.6%, respectively. CONCLUSIONS: Our telephone interview-based estimates of influenza morbidity were consistent with those from national influenza surveillance systems. Telephone surveys may provide an alternative method by which population-based influenza morbidity information can be gathered.

Bacterial meningitis in the United States, 1998-2007.

BACKGROUND: The rate of bacterial meningitis declined by 55% in the United States in the early 1990s, when the Haemophilus influenzae type b (Hib) conjugate vaccine for infants was introduced. More recent prevention measures such as the pneumococcal conjugate vaccine and universal screening of pregnant women for group B streptococcus (GBS) have further changed the epidemiology of bacterial meningitis. METHODS: We analyzed data on cases of bacterial meningitis reported among residents in eight surveillance areas of the Emerging Infections Programs Network, consisting of approximately 17.4 million persons, during 1998-2007. We defined bacterial meningitis as the presence of H. influenzae, Streptococcus pneumoniae, GBS, Listeria monocytogenes, or Neisseria meningitidis in cerebrospinal fluid or other normally sterile site in association with a clinical diagnosis of meningitis. RESULTS: We identified 3188 patients with bacterial meningitis; of 3155 patients for whom outcome data were available, 466 (14.8%) died. The incidence of meningitis changed by -31% (95% confidence interval [CI], -33 to -29) during the surveillance period, from 2.00 cases per 100,000 population (95% CI, 1.85 to 2.15) in 1998-1999 to 1.38 cases per 100,000 population (95% CI 1.27 to 1.50) in 2006-2007. The median age of patients increased from 30.3 years in 1998-1999 to 41.9 years in 2006-2007 (P<0.001 by the Wilcoxon rank-sum test). The case fatality rate did not change significantly: it was 15.7% in 1998-1999 and 14.3% in 2006-2007 (P=0.50). Of the 1670 cases reported during 2003-2007, S. pneumoniae was the predominant infective species (58.0%), followed by GBS (18.1%), N. meningitidis (13.9%), H. influenzae (6.7%), and L. monocytogenes (3.4%). An estimated 4100 cases and 500 deaths from bacterial meningitis occurred annually in the United States during 2003-2007. CONCLUSIONS: The rates of bacterial meningitis have decreased since 1998, but the disease still often results in death. With the success of pneumococcal and Hib conjugate vaccines in reducing the risk of meningitis among young children, the burden of bacterial meningitis is now borne more by older adults. (Funded by the Emerging Infections Programs, Centers for Disease Control and Prevention.).

Adherence to perinatal group B streptococcal prevention guidelines.

OBJECTIVE: To estimate compliance with the 2002 revised perinatal group B streptococci (GBS) prevention guidelines in Tennessee, which recommend universal GBS screening of pregnant women at 35-37 weeks of gestation and, when indicated, administration of intrapartum chemoprophylaxis. METHODS: Active Bacterial Core surveillance conducts active, population-based surveillance for invasive GBS disease in 11 Tennessee counties. A retrospective case-cohort study was conducted using a stratified random sample of all live births in surveillance hospitals during 2003-2004, including all early-onset GBS cases. Factors associated with GBS screening and lack of optimal GBS chemoprophylaxis were analyzed using logistic regression. RESULTS: Screening was performed for 84.7% of pregnant women, but 26.3% of prenatal tests with documented test dates were performed before 35 weeks of gestation. Among women with an indication for GBS prophylaxis, 61.2% received optimal chemoprophylaxis, defined as initiation of a recommended antibiotic 4 hours or more before delivery. When the analysis was restricted to women who were admitted 4 hours or more before delivery, 70.9% received optimal chemoprophylaxis. Women not receiving optimal chemoprophylaxis were more likely to have penicillin allergy (11.7% compared with 2.5%, adjusted odds ratio [OR] 8.58, 95% confidence interval [CI] 1.57-47.04) or preterm delivery (45.5% compared with 13.2%, adjusted OR 5.52, 95% CI 2.29-13.30) and were less likely to have received the recommended prenatal serologic testing for other infectious diseases (77.9% compared with 91.1%, adjusted OR 0.30, 95% CI 0.09-0.98). Forty cases of early-onset GBS were identified (0.36 per 1,000 live births); 25% of these neonates were born to women who received screening at 35 weeks of gestation or later and, when indicated, optimal chemoprophylaxis. CONCLUSION: Universal prenatal GBS screening was implemented widely in Tennessee, although the timing of screening and administration of chemoprophylaxis often were not optimal. A substantial burden of early-onset GBS disease occurs despite optimal prenatal screening and chemoprophylaxis, suggesting that alternative strategies, such as vaccination, are needed. LEVEL OF EVIDENCE: II.

Sickle cell trait, hemoglobin C trait, and invasive pneumococcal disease.

BACKGROUND: The cause of historically higher rates of invasive pneumococcal disease among blacks than whites has remained unknown. We tested the hypothesis that sickle cell trait or hemoglobin C trait is an independent risk factor for invasive pneumococcal disease. METHOD: Eligible children were born in Tennessee (1996-2003), had a newborn screen, enrolled in TennCare aged <1 year, and resided in a Tennessee county with laboratory-confirmed, pneumococcal surveillance. Race/ethnicity was ascertained from birth certificates. Children were followed through 2005 until loss of enrollment, pneumococcal disease episode, fifth birthday, or death. We calculated incidence rates by race/ethnicity and hemoglobin type before and after pneumococcal conjugate vaccine (PCV7) introduction. Poisson regression analyses compared invasive pneumococcal disease rates among blacks with sickle cell trait or hemoglobin C trait with whites and blacks with normal hemoglobin, controlling for age, gender, time (pre-PCV7, transition year, or post-PCV7) and high-risk conditions (eg, heart disease). RESULTS: Over 10 years, 415 invasive pneumococcal disease episodes occurred during 451,594 observed child-years. Before PCV7 introduction, disease rates/100,000 child-years were 2941 for blacks with sickle cell disease, 258 for blacks with sickle cell trait or hemoglobin C trait and 188, 172, and 125 for blacks, whites, and Hispanics with normal hemoglobin. Post-PCV7, rates declined for all groups. Blacks with sickle cell trait or hemoglobin C trait had 77% (95% CI = 22-155) and 42% (95% CI = 1-100) higher rates than whites and blacks with normal hemoglobin. CONCLUSION: Black children with sickle cell trait or hemoglobin C trait have an increased risk of invasive pneumococcal disease.

Sustained reductions in invasive pneumococcal disease in the era of conjugate vaccine.

BACKGROUND: Changes in invasive pneumococcal disease (IPD) incidence were evaluated after 7 years of 7-valent pneumococcal conjugate vaccine (PCV7) use in US children. METHODS: Laboratory-confirmed IPD cases were identified during 1998-2007 by 8 active population-based surveillance sites. We compared overall, age group-specific, syndrome-specific, and serotype group-specific IPD incidence in 2007 with that in 1998-1999 (before PCV7) and assessed potential serotype coverage of new conjugate vaccine formulations. RESULTS: Overall and PCV7-type IPD incidence declined by 45% (from 24.4 to 13.5 cases per 100,000 population) and 94% (from 15.5 to 1.0 cases per 100,000 population), respectively (P< .01 all age groups). The incidence of IPD caused by serotype 19A and other non-PCV7 types increased from 0.8 to 2.7 cases per 100,000 population and from 6.1 to 7.9 cases per 100,000 population, respectively (P< .01 for all age groups). The rates of meningitis and invasive pneumonia caused by non-PCV7 types increased for all age groups (P< .05), whereas the rates of primary bacteremia caused by these serotypes did not change. In 2006-2007, PCV7 types caused 2% of IPD cases, and the 6 additional serotypes included in an investigational 13-valent conjugate vaccine caused 63% of IPD cases among children <5 years-old. CONCLUSIONS: Dramatic reductions in IPD after PCV7 introduction in the United States remain evident 7 years later. IPD rates caused by serotype 19A and other non-PCV7 types have increased but remain low relative to decreases in PCV7-type IPD.