department of health and human services department of health and human services department of health and human services department of health and human services department of health and human services Centers for Disease Control and Prevention Centers for Disease Control and Prevention Centers for Disease Control and Prevention Centers for Disease Control and Prevention Centers for Disease Control and Prevention INSIDE 789 Update: Influenza Activity -United States and Worldwide, 2006-07 Season, and Composition of the 2007-08 Influenza Vaccine 794 Notices to Readers 796 QuickStats - <100,000 platelets/mm 3 . FIGURE 1. Jurisdictions affected by dengue fever outbreak -Texas-Mexico border,# Dengue Hemorrhagic Fever -U.S.-Mexico Border, 2005
Dengue fever is a mosquito-transmitted disease caused by any of four closely related virus serotypes (DEN-1, DEN-2, DEN-3, and DEN-4) of the genus Flavivirus. Infection with one of these serotypes provides lifelong immunity to the infecting serotype only. Therefore, persons can acquire a second dengue infection from a different serotype, and second infections place them at greater risk for dengue hemorrhagic fever (DHF), the more severe form of the disease (1). DHF is characterized by bleeding manifestations, thrombocytopenia,- and increased vascular permeability that can lead to life-threatening shock (2). In south Texas, near the border with Mexico, sporadic, locally acquired outbreaks of dengue fever have been reported previously; however, on the Texas side of the border, these outbreaks have not included recognized cases of locally acquired DHF in persons native to the area. In July 2005, a case of DHF was reported in a resident of Brownsville, Texas (Figure 1). In August 2005, health authorities in the neigh-boring state of Tamaulipas, Mexico, reported an ongoing dengue outbreak with 1,251 cases of dengue fever, including 223 cases (17.8%) of DHF. To characterize this dengue outbreak, the Texas Department of State Health Services (TDSHS), Mexican health authorities, and CDC conducted a clinical and epidemiologic investigation. This report summarizes the results of that investigation, which determined that the percentage of DHF cases associated with dengue fever outbreaks at the Texas-Tamaulipas border has increased. Health-care providers along the U.S. border with Mexico should be vigilant for DHF and familiar with its diagnosis and management to reduce the number of severe illnesses and deaths associated with outbreaks of dengue fever.

# Autochthonous DHF Case Report
On June 24, 2005, a woman from Brownsville, Texas, had acute onset of fever, chills, headache, nausea, vomiting, abdominal pain, arthralgia, and myalgia. As a youth, the patient had resided across the border in the city of Matamoros in Tamaulipas, Mexico; however, she had been a Brownsville resident for 16 years with the exception of 1 year in Houston, Texas. After she became ill, the woman crossed the border into Matamoros for the first time in approximately 2 months, where she visited a clinician and was given antibiotics. On June 28, the woman was hospitalized in Matamoros with a diagnosis of probable dengue fever and urinary tract infection. During her 3-day hospitalization in Mexico, she had thrombocytopenia (62,000 platelets/mm 3 ) but no hemorrhagic manifestations; she was treated with fluids and antibiotics and discharged.
On July 1, the woman reentered the United States and sought treatment for continued fever, chills, vomiting, and abdominal pain. She was admitted to a hospital in Brownsville, Texas, where her blood pressure was 94/70 mm Hg, and laboratory testing indicated proteinuria, hematuria, and a further decrease in platelet count (43,000/mm 3 ). She was given antibiotics for suspected partially treated urinary tract infection and fluids for dehydration. During her hospital stay, the patient's platelet count dropped to 39,000/ mm 3 and albumin to 2.9 g/100 mL; a fecal occult blood test was positive, and pleural effusion was noted on ultrasound. Upon discharge on July 4, her platelet count had increased to 118,000/mm 3 . The woman was discharged with a diagnosis of possible murine typhus or viral infection and instructions to take a course of doxycycline.
Although the woman's clinical characteristics (i.e., acute fever, platelet count <100,000/mm 3 , evidence of bleeding  and plasma leakage) were consistent with World Health Organization (WHO) criteria for DHF (Box) (2), dengue was not diagnosed at the Brownsville hospital. Subsequently, results from a July 3

# BOX. World Health Organization case definition for dengue hemorrhagic fever
The following must all be present: - Fever, or history of acute fever, lasting 2-7 days, occasionally biphasic. - Hemorrhagic tendencies, evidenced by at least one of the following: -a positive tourniquet test; -petechiae, ecchymoses, or purpura; -bleeding from the mucosa, gastrointestinal tract, injection sites, or other locations; -hematemesis or melena.
- Thrombocytopenia (<100,000 platelets/mm 3 ).
- Evidence of plasma leakage because of increased vascular permeability, manifested by at least one of the following: -an increase in the hematocrit >20% above average for age, sex, and population; -a decrease in the hematocrit following volumereplacement treatment >20% of baseline; -signs of plasma leakage such as pleural effusion, ascites, and hypoproteinemia.
treated at three hospitals in Matamoros. Fifty-nine percent of the patients were female. Ages ranged from 30 to 76 years (median 47.5 years) among the Cameron County cases and from 7 to 70 years (median 36.0 years) among the Matamoros cases. In addition to fever, 82% had myalgia, 78% headache, 41% abdominal pain, 23% rash, and 19% had underlying chronic diseases. No fatalities were recorded. A total of 16 (64.0%) of the 25 dengue cases from Cameron County and 34 (32.7%) of the 104 cases from Matamoros met WHO criteria for DHF (Box). Eleven of the 50 DHF cases, including one from Cameron County, were classified as WHO grade III, or dengue shock syndrome, with early or mild evidence of hypotension or shock. The remaining 39 DHF cases were classified as WHO grade II.  Serosurveys. Because many dengue infections are asymptomatic, and most ill persons likely do not seek medical attention, investigators conducted serosurveys to assess the incidence of dengue infection in the populations of Matamoros and Brownsville. Serosurveys also enable estimation of the population susceptible to second dengue infections and DHF. For the serosurveys, a two-stage cluster design was used to obtain a representative sample of households from Brownsville and Matamoros (6). Thirty census tracts were selected systematically from each city after stratifying by income. Four households were selected from each census tract after mapping and selecting a random start point and random direction for sampling.
At each participating household, all residents present and aged >5 years were asked to provide a blood sample and demographic information. Serum samples were tested for IgM and IgG antibodies to dengue virus by ELISA. The seroincidence of recent dengue infection was defined by IgM antibodies >0.2 optical density (OD). Seroprevalence was defined as the presence of IgG antibodies >1:40. Data were weighted to reflect probability of selection, taking into account the population and numbers of households per census tract and size of household.
In Matamoros, 240 households were visited during December 5-10, and 143 (59.6%) had residents at home. Blood samples were obtained from 131 persons in 111 homes. Of these samples, 30 were anti-dengue IgM posi-serum sample from the woman obtained by the regional Texas Border Infectious Disease Surveillance (BIDS) project tested positive for dengue immunoglobulin M (IgM) by enzyme-linked immunosorbent assay (ELISA) and had an elevated titer of immunoglobulin G (IgG) antibodies to dengue fever (1:655,350); this was interpreted as indicative of a secondary dengue infection (1).

# Outbreak Investigation and Response
Dengue fever case finding. On August 27, 2005, Tamaulipas State Health Services reported to TDSHS that an outbreak of dengue fever in the border state had grown to 1,251 cases that met the Mexico case definition (i.e., fever and at least two of the following symptoms: headache, myalgia, arthralgia, and rash). Using WHO criteria for DHF, Tamaulipas health authorities had classified 223 (17.8%) of the cases as DHF, an increase in the percentage classified as DHF from 2000-2004, when 541 dengue fever cases were reported, including 20 cases (3.7%) classified as DHF.  In October, investigators in Texas and Tamaulipas began conducting expanded outbreak case finding, including active surveillance in local hospitals, with laboratory testing encouraged for patients with undifferentiated fever as part of the BIDS project. In Cameron County, Texas, where Brownsville is the county seat, TDSHS identified 24 additional cases of laboratory-confirmed dengue fever  , including two additional cases of locally transmitted dengue fever and 22 cases associated with travel to Mexico; the cases had been reported during August-November (Figure 2). The serotype most commonly associated with the outbreak was identified as DEN-2 (i.e., 27 of 28 viral isolates in Tamaulipas). Molecular analysis of isolates at CDC indicated that the circulating strain of DEN-2 was one previously associated with DHF in the Americas region (4,5). Plotting reports of cases by week determined that the border outbreak peaked in October and substantially subsided by December (Figure 2). DHF case finding. In December, investigators reviewed medical records of 129 patients who had been hospitalized and reported to public health authorities with both clinical and laboratory evidence of dengue fever, including 25 persons treated at three Cameron County hospitals and 104  DHF is classified into four grades of severity; grades III and IV are considered to be dengue shock syndrome. Grade I: Fever accompanied by nonspecific constitutional symptoms; the only hemorrhagic manifestation is a positive tourniquet test and/or easy bruising. Grade II: Spontaneous bleeding in addition to the manifestations of Grade I patients, usually in the forms of skin or other hemorrhages. Grade III: Circulatory failure manifested by a rapid, weak pulse and narrowing of pulse pressure or hypotension, with the presence of cold, clammy skin and restlessness. Grade IV: Profound shock with undetectable blood pressure or pulse (2).  (3,8), but locally acquired DHF has been reported only recently (9). The first report of locally acquired DHF in Texas, published in 2004, described a fatal case involving a woman originally from Southeast Asia (9). She presumably had acquired her first dengue infection in Asia and her second dengue infection in Val Verde, Texas, near the U.S.-Mexico border. However, the DHF case described in this report is the first in a Texas resident who was native to the U.S.-Mexico border area. Case-finding activities during the dengue outbreak identified 15 additional DHF cases on the Texas side of the border.
Entomologic, serologic and virologic conditions are now such that locally acquired DHF can occur in south Texas. The principal dengue vector, the Aedes aegypti mosquito, is well established in south Texas, as is Aedes albopictus, which also is capable of transmitting dengue (7,10;TDSHS, unpublished data, 2007). The finding that 38% of surveyed Brownsville residents have IgG antibodies to dengue indicates that a substantial proportion of the city population has been infected with the dengue virus and might be more susceptible to DHF if they receive a second infection with a heterologous dengue serotype. The presence in Brownsville of multiple dengue serotypes since 1980 might increase the likelihood for secondary dengue infections from a different serotype and increase the risk for DHF.
The findings in this report are subject to at least two limitations. First, more comprehensive laboratory testing

# United States
The national percentage of respiratory specimens testing positive for influenza and the proportion of outpatient visits to sentinel providers for influenza-like illness (ILI)- peaked in mid-February. Although influenza A (H1) viruses were most commonly isolated overall, influenza A (H3) viruses were more frequently identified than influenza A (H1) viruses from early March through May. A small number of influenza B viruses also were identified.  1). Of these, 18,817 (79.2%) were influenza A viruses and 4,936 (20.8%) were influenza B viruses. Among the influenza A viruses, 6,280 (33.4%) were subtyped; 3,912 (62.3%) were influenza A (H1) viruses and 2,368 (37.7%) were influenza A (H3) viruses. The proportion of specimens testing positive for influenza first exceeded 10% during the week ending December 23, 2006 (week 51), peaked at 28.0% during the week ending February 10, 2007 (week 6), and declined to less than 10% during the week ending April 28, 2007 (week 17). The proportion was above 10% positive for 14 consecutive weeks. The peak percentage of specimens testing positive for influenza during the previous three seasons ranged from 22.6% to 34.7%, and the peak occurred during early December to early March (1;CDC, unpublished data, 2007). During the previous three influenza seasons, the number of consecutive weeks during which more than 10% of specimens tested positive for influenza ranged from 13 to 17 weeks (1;CDC, unpublished data, 2007).

# Viral Surveillance

# Composition of the Influenza Vaccine for the 2007-08 Season

# Antigenic Characterization

# Influenza-Like Illness (ILI) Surveillance
The weekly percentage of patient visits to U.S. sentinel providers for ILI exceeded or was at baseline levels (2.1%)  during the weeks ending December 16, 2006-March 24, 2007 (weeks 50-12) and peaked twice, once at 3.0% for the week ending December 30, 2006 (week 52), and again at 3.5% for the week ending February 17, 2007 (week 7) (Figure 2). The increase in the percentage of patient visits for ILI during the week ending December 30, 2006 (week 52) might have been influenced by a reduction in routine health-care visits during the holiday season, as has occurred in previous seasons. During the previous three influenza seasons, the peak percentage of patient visits for ILI has ranged from 3.3% to 7.6% and the peak occurred during late December to mid-February (1; CDC, unpublished data, 2007).

# State-Specific Activity Levels
State and territorial epidemiologists report the geographic distribution of influenza in their state through a weekly influenza activity code. The geographic distribution of influenza activity peaked during the week ending February 24, 2007 (week 8), when 25 states reported widespread activity and 19 states reported regional activity.  Forty-one states reported widespread influenza activity at least once during the 2006-07 season. No states reported widespread influenza activity during the weeks ending April 21-May 19, 2007 (weeks 16-20). The peak number of states reporting widespread or regional activity during the previous three seasons ranged from 41 to 50 states (1; CDC, unpublished data, 2007).  Percentage  The national baseline is the mean percentage of visits for ILI during noninfluenza weeks for the previous three seasons plus two standard deviations. Noninfluenza weeks are those in which less than 10% of laboratory specimens are positive for influenza. National percentages of patient visits for ILI are weighted on the basis of state population.  Levels of activity are 1) no activity; 2) sporadic: isolated laboratory-confirmed influenza cases or a laboratory-confirmed outbreak in one institution, with no increase in ILI activity; 3) local: increased ILI , or at least two institutional outbreaks (ILI or laboratory-confirmed influenza) in one region with recent laboratory evidence of influenza in that region; virus activity no greater than sporadic in other regions; 4) regional: increased ILI activity or institutional outbreaks (ILI or laboratory-confirmed influenza) in at least two but less than half of the regions in the state with recent laboratory evidence of influenza in those regions; and 5) widespread: increased ILI activity or institutional outbreaks (ILI or laboratory-confirmed influenza) in at least half the regions in the state with recent laboratory evidence of influenza in the state.

# Influenza-Associated Pediatric Hospitalization

# MMWR August 10, 2007
systems likely result from different case-finding methods, the diagnostic tests used, and the populations monitored. 

# Pneumonia-and Influenza-Related Mortality
During the 2006-07 influenza season, the percentage of deaths attributed to pneumonia and influenza (P&I) did not exceed the epidemic threshold in the 122 Cities Mortality Reporting System (Figure 3). The percentage of P&I deaths peaked three times, once at 7.5% during the week ending January 20, 2007 (week 3), once at 7.7% during the week ending February 24, 2007 (week 8), and again at 7.5% during the week ending March 24, 2007 (week 12). During the previous three influenza seasons, the peak percentage of P&I deaths ranged from 7.8% to 10.4%, and the total number of weeks above the epidemic threshold ranged from one to 16 (1; CDC, unpublished data, 2007).

# Influenza-Associated Pediatric Mortality
As of August 6, 2007, among persons aged 6 months for whom vaccination status was known, 50 (94%) had not been vaccinated against influenza. These data are provisional.

# Worldwide
During the 2006-07 influenza season, influenza A (H1), A (H3), and B viruses cocirculated worldwide. In Africa, small numbers of influenza A and B viruses were reported. In Europe and Asia, influenza A (H3) viruses were identified most frequently, but influenza A (H1) viruses circulated at low levels. Influenza B viruses circulated at lower levels overall in Asia and Europe but predominated in some countries.

# Human Infections with Avian Influenza A (H5N1) Viruses
From December 1, 2003, through July 25, 2007, a total of 319 human cases of avian influenza A (H5N1) infection were reported to WHO (2). Of these, 192 (60%) were fatal (Table ). All cases were reported from Asia (Azerbaijan, Cambodia, China, Indonesia, Iraq, Laos, Thailand, Turkey, and Viet Nam) and Africa (Djibouti, Egypt, and Nigeria). To date, no human case of avian influenza A (H5N1) virus infection has been identified in the United States.   At the June 2007 Annual Meeting of the Council of State and Territorial Epidemiologists (CSTE), members voted to ratify a position statement adopted by the CSTE Executive Committee in January 2007 that adds human infections with novel influenza A viruses to the list of nationally notifiable diseases and conditions reportable to the National Notifiable Disease Surveillance System. Novel influenza A viruses are defined as those isolated from a human but subtyped as nonhuman, or those that cannot be subtyped by standard methods. Human infections with novel influenza A viruses that can be transmitted from person-toperson might signal the beginning of an influenza pandemic. Rapid reporting of human infections with novel influenza A viruses will facilitate prompt detection and characterization of influenza A viruses with pandemic potential and accelerate implementation of effective public health responses. In addition, influenza-associated pediatric deaths were maintained as a nationally notifiable disease reportable to the National Notifiable Disease Surveillance System.
In May 2007, health authorities in the United Kingdom identified four persons, two in Wales and two in northwest England, who were infected with a low pathogenic avian influenza A (H7N2) virus (4). All four persons had been exposed to infected poultry at a farm in Wales; limited evidence of human-to-human transmission has been associated with low pathogenic avian influenza viruses such as influenza A (H7N2) virus (4). The United Kingdom inci-    (1). Background information regarding meningococcal disease and the vaccine, including a discussion of duration of protection and use of the vaccine for outbreak control, has been published previously (1).
In June 2007, ACIP revised its recommendation to include routine vaccination of all persons aged 11-18 years with 1 dose of MCV4 at the earliest opportunity. Persons aged 11-12 years should be routinely vaccinated at the 11-12 years health-care visit as recommended by ACIP (2). ACIP continues to recommend routine vaccination for persons aged 19-55 years who are at increased risk for meningococcal disease: college freshmen living in dormitories, microbiologists routinely exposed to isolates of Neisseria meningitidis, military recruits, travelers to or residents of countries in which N. meningitidis meningitis is hyperendemic or epidemic, persons with terminal complement component deficiencies, and persons with anatomic or functional asplenia.
The ACIP goal is routine vaccination of all adolescents with MCV4 beginning at age 11 years. ACIP and partner organizations, including the American Academy of Pediatrics, American Academy of Family Physicians, American Medical Association, and Society for Adolescent Medicine, recommend a health-care visit for children aged 11-12 years to receive recommended vaccinations and indicated preventive services. This visit is the optimal time for adolescents to receive MCV4. In addition, because the incidence of meningococcal disease increases during adolescence, health-care providers should vaccinate previously unvaccinated persons aged 11-18 years with MCV4 at the earliest possible health-care visit. College freshmen living in dormitories are at increased risk for meningococcal disease and should be vaccinated with MCV4 before college entry if they have not been vaccinated previously. Because of difficulties in targeting freshmen in dormitories, colleges may elect to target their vaccination campaigns to all matriculating freshmen (1).
The ACIP meningococcal vaccine workgroup reviewed updated data on MCV4 use and supply projections and data presented previously on the epidemiology of meningococcal disease, safety, and the cost-effectiveness of MCV vaccination strategies. On the basis of these data, expert opinion of the workgroup members, and feedback from partner organizations, the workgroup revised the MCV4 recommendations, which were approved by ACIP at the June 2007 meeting.
The 2005 ACIP MCV4 recommendation was influenced by concern that implementation of MCV4 recommendations might be hindered by reduced vaccine supply during the first few years of production. In 2005 and 2006, peaks in demand were observed during the months when children were returning to school after summer vacation, leading to limited vaccine availability (3,4). However, as of June 2007, ACIP expects supply of MCV4 to be sufficient to meet increased vaccine demand resulting from the revised recommendations. ACIP anticipates that recommending vaccination of all persons aged 11-18 years will improve MCV4 vaccination coverage in this age group and simplify provider decisions to vaccinate.
ACIP encourages health-care providers to vaccinate with MCV4 throughout the year to minimize seasonal increases in demand during July and August when students prepare to return to school from summer vacation. Vaccine providers should administer MCV4 and Tdap (tetanus toxoid, reduced diphtheria toxoid and acellular pertussis) vaccine to persons aged 11-18 years during the same visit if both vaccines are indicated and available. If simultaneous vaccination is not feasible (e.g., a vaccine is not available), MCV4 and Tdap can be administered using any order of administration (5). When making decisions about timing of vaccination, providers should consider that eligibility for the Vaccines for Children Program ends at age 19 years.
Guillain-Barre syndrome (GBS) has been associated with receipt of MCV4 (6). Persons with a history of GBS might be at increased risk for postvaccination GBS; therefore, a history of GBS is a relative contraindication to receiving MCV4. Persons recommended to receive meningococcal vaccination who have a history of GBS (or their parents) should discuss the decision to be vaccinated with their health-care provider (6). Meningococcal polysaccharide vaccine (MPSV4) is an acceptable alternative for short-term protection against meningococcal disease (3-5 years). Providers who have questions about ordering MCV4 or MPSV4 may contact Sanofi Pasteur by telephone at 1-800-VAC-CINE or online at .  Organizations are responsible for setting up their own viewing locations and are encouraged to register their locations as soon as possible so that potential viewers can access information online. Additional information regarding the broadcast and directions for establishing and registering a viewing location are available at  npin-broadcast.org. The broadcast will be available for 3 years after its initial airing at . DVDs can be ordered by telephone, 800-458-5231. Among both men and women, non-Hispanic blacks (51.6% of men and 53.5% of women) were more likely to report ever being tested for HIV than Hispanics (35.7% of men and 46.1% of women) and non-Hispanic whites (30.5% of men and 33.5% of women). Overall, women (37.8%) were more likely than men (33.7%) to report ever being tested for HIV.

# Notice to Readers

# Satellite Broadcast and Webcast: Current Challenges and Successes in HIV Prevention with Hispanics/Latinos
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