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From the Centers for Disease Control and Prevention |

West Nile Virus Activity—New York and New Jersey, 2000 FREE

JAMA. 2000;284(7):823-824. doi:10.1001/jama.284.7.823.
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WEST NILE VIRUS ACTIVITY—NEW YORK AND NEW JERSEY, 2000

MMWR. 2000;49:640-642

In late August 1999, an outbreak of encephalitis caused by West Nile virus (WNV) was detected in New York City and subsequently identified in neighboring counties.1 In response, an extensive mosquito-control and risk-reduction campaign was initiated, including aerial and ground applications of mosquito adulticides throughout the affected areas. No human WNV infections were found in New York City with an onset date after the campaign was completed. Cases continued to occur among humans in surrounding counties that did not undertake mosquito-control efforts until later, suggesting that the campaign may have reduced human risk. In May 2000, CDC issued guidelines to direct national surveillance, prevention, and control efforts2 and provided funds to support these efforts in 19 state and local health departments where WNV transmission had occurred or where transmission would probably occur based on known bird migration patterns. This report presents the findings of surveillance activities.

From May 6 through July 8, 2000, state and local health departments confirmed WNV infections in 26 birds from five counties in New York and New Jersey. Twenty-one infections have been confirmed in American crows in New York and New Jersey, four in blue jays, and one in a red-tailed hawk. The first infected crow was found May 22 in Rockland County, and the most recently infected crows were found July 6 and 8 in the same county. Fourteen infected crows identified in New York were found in Rockland (eight crows), Suffolk (three), Westchester (one), and Richmond (Staten Island) (two) counties. Seven infected crows were found in Bergen County, New Jersey. Rockland County also identified four blue jays with WNV infection, and one infected hawk was found in Westchester County. WNV has been detected by polymerase chain reaction molecular methods in mosquito pools collected in Westchester County (Aedes japonicus) and in Suffolk County (mixed Culex species). No cases of human or equine infection have been reported in the region or in surrounding states.

Reported by:

A Novello, MD, D White, PhD, L Kramer, PhD, C Trimarchi, MS, M Eidson, DVM, D Morse, MD, P Smith, MD, State Epidemiologist, New York State Dept of Health; W Stone, PhD, Dept of Environmental Conservation, Albany; Rockland County Health Dept, Pomona; Suffolk County Health Dept, Hauppague; Westchester County Health Dept, New Rochelle; J Miller, MD, M Layton, MD, New York City Dept of Health. Bergen County Health Dept, Paramus; W Crans, PhD, Rutgers Univ, New Brunswick; F Sorhage, DVM, E Bresnitz, MD, State Epidemiologist, New Jersey Dept of Health and Senior Svcs. National Wildlife Health Center, US Geologic Survey, Madison, Wisconsin. Arbovirus Diseases Br, Div of Vectorborne Infectious Diseases, National Center for Infectious Diseases, CDC.

CDC Editorial Note:

WNV is transmitted readily by mosquitoes. Culex species were the primary vectors of WNV during previous outbreaks and epizootics; however, WNV also has been isolated from many species of Aedes and Anopheles.3 In New York, WNV was isolated primarily from Culex species mosquitoes during the 1999 outbreak; WNV also was detected in overwintering Culex species in New York City. These findings suggest an important role for these species in the transmission of WNV in the United States. Aedes japonicus was detected recently in the United States, and research is needed to determine the flight range and feeding behavior of mosquitoes and to better understand the risk for transmission to humans.

The susceptibility of crows to infection and death is a sensitive surveillance tool that is unique to the United States.4 No data exist from which to infer the mosquito WNV infection rate associated with a small number of dead crows in an area, or to infer the risk to humans. Data also are lacking to infer where and how the dead crows acquired infection. Time of year and reproductive status of the crow population may be used to indicate whether transmission occurred locally. On the basis of the known nesting habits of crows, the finding of infected crows in early summer suggest local transmission in Rockland, Westchester, Suffolk, and Bergen counties. Data from the U.S. Geologic Survey's National Wildlife Health Center indicate that crows infected with WNV are likely to have high viremias and also are likely to be sedentary approximately 4 days before death, suggesting that they can be a source of WNV for mosquitoes in areas where they are found (National Wildlife Health Center, unpublished data, 2000).

On the basis of the surveillance indicators described in this report and the phased response plan,2 CDC recommends the following for those areas where evidence suggests local transmission of WNV:

  1. Intensify local and regional Culex mosquito larval control to prevent the emergence of adult mosquitoes that feed on birds and may contribute to the virus amplification/transmission cycle.

  2. Expand and intensify surveillance activities in and around areas where WNV-infected birds are found. Additional surveillance data about the species population densities, virus infection rates in mosquito vectors, seroprevalence in resident wild birds (e.g., house sparrows), and seroconversion rates in sentinel chickens will permit a more accurate interpretation of dead bird surveillance data and the relative risk for human disease.

  3. Continue active WNV surveillance to determine the presence of new or expanding WNV transmission foci.

  4. Reinforce public education and outreach programs to reduce mosquito breeding sites around the home and use personal protective measures.

  5. Implement, if necessary, focal adult mosquito control to reduce the number of virus-infected mosquitoes, thus reducing the immediate risk to humans. Mosquito species that feed on birds probably are driving enzootic transmission in 2000 and probably are the vector for human cases.5 Adult mosquitoes should be controlled within approximately a 2-mile radius around the area where a WNV positive dead bird or infected mosquitoes are found. This radius depends on the length of time between transmission of the virus and the execution of control; as the time period increases, larger areas must be treated.

  6. Consider aerial spraying of adulticides in areas where WNV transmission is sustained and further amplification is evident despite intensive local mosquito control efforts.

  7. Monitor adult and larval mosquito control efforts to ensure that the control programs are effectively reducing vector mosquito densities and virus infection rates.

Counties where WNV transmission occurred in 1999, but has not been identified in 2000, should maintain active surveillance for WNV and continue larval mosquito-control, such as controlling larval mosquito habitats, particularly around homes in suburban and urban areas and monitoring Culex larval habitats regularly for mosquito breeding.

References: 5 available

PROGRESS TOWARD POLIOMYELITIS ERADICATION—EUROPEAN REGION, 1998-JUNE 2000

MMWR. 2000;49:656-660

1 table omitted

In 1988, the World Health Assembly resolved to eradicate poliomyelitis globally by 2000.1 Substantial progress has been made since 1995, when the World Health Organization (WHO) European Region (EUR), comprising 51 member states (including Israel and the Central Asian Republics), accelerated efforts toward polio eradication.2-4 This report summarizes progress toward polio eradication during 1998-June 2000, and suggests that indigenous transmission of wild poliovirus has been interrupted in EUR.

Routine vaccination coverage

In 1999, 38 EUR countries routinely used oral poliovirus vaccine (OPV) for infant vaccination, seven used inactivated poliovirus vaccine (IPV), and six used sequential IPV-OPV schedules. In 1998, the regional average for coverage with a primary series of polio vaccination by age 1 year was 94% (range: 77%-100%, with 26 countries reporting), compared with 83% in 1993 (range: 45%-100%, with 46 countries reporting); coverage levels in many of the Newly Independent States of the Former Soviet Union improved to pre-independence levels after reaching their lowest points during the economic transitions of the early 1990s.

Supplemental vaccination activities

From 1995 to 1997, National Immunization Days (NIDs)* were conducted in 18 contiguous countries of the WHO Eastern Mediterranean (Afghanistan, Islamic Republic of Iran, Iraq, Jordan, Lebanon, Pakistan, Palestinian Authority, and Syrian Arab Republic) and European regions (Armenia, Azerbaijan, Georgia, Kazakhstan, Kyrgyzstan, Russian Federation, Tajikistan, Turkey, Turkmenistan, and Uzbekistan) as part of "Operation MECACAR" (Eastern Mediterranean, Caucasus, and Central Asian Republics). Reported coverage with two doses of OPV was greater than 95% in each year.2 Beginning in the fall of 1997 with "mopping-up" vaccination,† coordinated activities in countries of the two regions continued as "Operation MECACAR Plus." In 1998, all MECACAR countries participated in NIDs. Since 1999, activities have been more limited; sub-NIDs or supplemental vaccination programs were not conducted in some MECACAR countries of EUR. NIDs were conducted during April-May 2000 in Tajikistan, Turkey, Turkmenistan, and Uzbekistan, and sub-NIDs in Armenia, Azerbaijan, and Russian Federation, with reported coverage greater than or equal to 93% for each round, and sub-NIDs in Bosnia and Herzegovina, with coverage greater than or equal to 90%. Since fall 1998, the quality of supplemental vaccination in high-risk eastern and southeastern provinces of Turkey has improved dramatically because of improved provincial planning, house-to-house vaccination, supervision, and social mobilization.

Surveillance

By 1997, all 17 countries where polio was recently endemic (i.e., polio cases reported since 1992) had established AFP surveillance. In addition, 22 countries where polio is not endemic also routinely reported AFP surveillance data. From January 1999 through June 2000, all but three of the 17 countries where polio was recently endemic (Albania, Azerbaijan, and Bosnia and Herzegovina) have achieved the minimum AFP reporting rate indicative of sensitive surveillance (greater than or equal to 1 nonpolio AFP case per 100,000 children aged less than 15 years annually). Although the quality of AFP surveillance has varied in some countries where polio was recently endemic, many have consistently reported rates greater than or equal to 1 since 1998. The overall collection rate for two adequate stool samples‡ from AFP case-patients in countries where polio was recently endemic increased from 78% in 1998 to 88% by June 2000. During 1999-2000, most countries consistently achieved the WHO-recommended target of two adequate stool specimens collected from at least 80% of persons with AFP. Training and assessment programs have been conducted since 1997, with resources focused on improved monitoring, supervision, and active surveillance. Since 1999, emphasis has been placed on monitoring AFP surveillance performance of lower administrative levels within countries where polio was recently endemic, enabling more appropriate tailoring of corrective interventions. Since 1999, all 39 countries conducting AFP surveillance are reporting case-based AFP surveillance data weekly to the WHO regional office. By June 2000, completeness of reports received for weekly reporting was 86% and timeliness of reporting was 82%.

EUR laboratory network

The EUR polio laboratory network consists of 39 laboratories: 32 national, one subregional, and six regional reference laboratories (four serve also as national laboratories). Annual WHO accreditation of national laboratories is ongoing4; 36 (92%) network laboratories have received full accreditation. All AFP cases reported in 2000 have been processed in fully accredited laboratories. The timeliness of specimen transport to national laboratories has been inadequate in nine countries where less than 50% of specimens reached a national laboratory within 3 days of collection.

Incidence of polio

From 1991 through 1996, the number of confirmed polio cases§ reported annually in EUR ranged from 177 to 297; in 1997, seven cases from two countries (Tajikistan and Turkey) were reported. During February-November 1998, wild poliovirus type 1 was isolated in 24 cases and wild poliovirus type 3 in two cases in eight eastern and southeastern provinces of Turkey. The last reported case occurred in Agri province with paralysis onset on November 26, 1998.

Certification process

The European Regional Commission for the Certification of Poliomyelitis Eradication has begun reviewing documentation on the vaccination and surveillance activities of EUR countries. Forty-nine member states have formed national certification committees to review country vaccination, laboratory, and epidemiologic surveillance data and submit documentation to the regional commission. Documentation Reported by: Communicable Diseases Unit, World Health Organization Regional Office for Europe, Copenhagen, Denmark. Dept of Vaccines and Biologicals, World Health Organization, Geneva, Switzerland. Respiratory and Enteric Viruses Br, Div of Viral and Rickettsial Diseases, National Center for Infectious Diseases; Vaccine Preventable Disease Eradication Div, National Immunization Program, CDC.

CDC Editorial Note:

Indigenous poliovirus transmission probably was interrupted in EUR countries in 1998; this status is attributed to improvements in routine vaccination coverage and the successful implementation of coordinated supplemental vaccination through Operation MECACAR and MECACAR Plus. In addition, AFP surveillance in nearly all EUR countries where polio was recently endemic has improved substantially. Along with continued observation, the quality of surveillance and timely transport of specimens in some areas of the region need further improvement to document that indigenous transmission has been interrupted and that any transmission secondary to imported poliovirus is detected promptly. Strengthening of surveillance and specimen transport is particularly important in some areas of Turkey.

Eastern and southeastern areas of Turkey adjacent to Syria, Iran, and Iraq remain at high risk for wild poliovirus transmission; wild polioviruses have been isolated from AFP cases in Iraq during 1999 and in early 2000.4,6 Although cross-border travel is generally prohibited and tightly monitored, Tajikistan, Turkmenistan, and Uzbekistan remain at risk for polio because of ongoing poliovirus transmission in neighboring Afghanistan.7 Interregional and intercountry efforts are ongoing to coordinate surveillance and supplementary vaccination activities in key high-risk border areas. Supplemental vaccination activities will be needed at least through 2002 in Tajikistan, Turkey, Turkmenistan, and Uzbekistan under Operation MECACAR Plus. This activity will be coordinated with bordering Eastern Mediterranean Region (EMR) countries and include mopping-up campaigns in October and November 2000 to ensure interruption of any remaining chains of poliovirus transmission and to impede circulation in the case of reintroduction of virus.

EUR priorities include (1) maintaining and strengthening AFP surveillance systems, particularly in the Caucasus, Turkey, and the Central Asian Republics; (2) conducting high-quality NIDs or sub-NIDs through Operation MECACAR Plus in selected countries with persistent high risk for wild poliovirus circulation, in coordination with bordering EMR countries; (3) implementing coordinated house-to-house supplemental vaccination activities among key border area populations; (4) maintaining and strengthening the political commitment of governments for polio eradication and certification; (5) consolidating the support of donor governments and partner agencies to ensure sufficient financial and human resources∥; and (6) implementing laboratory containment of wild poliovirus and potentially infectious materials. These activities will ensure that the interruption of poliovirus transmission is maintained and that the region can be certified as polio-free by 2003.

References: 7 available

*Mass campaigns over a short period (days to weeks) in which two doses of OPV are administered to all children in the target age group, regardless of previous vaccination history, with an interval of 4-6 weeks between doses.

†Focal mass campaign in high-risk areas over a short period (days to weeks) in which two doses of OPV are administered during house-to-house visits to all children in the target age group, regardless of previous vaccination history, with an interval of 4-6 weeks between doses.

‡Two stool specimens collected within 14 days of onset of paralysis at an interval of at least 24 hours. WHO recommends that greater than or equal to 80% of patients with AFP have two adequate specimens collected.

§A confirmed case of polio is defined under the virologic scheme of classification as AFP with laboratory-confirmed wild poliovirus infection; in countries where virologic surveillance is inadequate, clinical cases have either residual paralysis at 60 days, death, or no follow-up investigation at 60 days. Since 1997, all countries in EUR but Tajikistan have used the virologic scheme of classification of AFP cases, for which some AFP cases with residual paralysis at 60 days, death, or no follow-up investigation may be considered as polio-compatible cases. Since 1999, the virologic classification scheme has been applied throughout EUR.

∥Polio eradication efforts in EUR have been supported by the governments of countries where polio was recently endemic, WHO, United Nations Children's Fund (UNICEF), Rotary International, U.S. Agency for International Development, the Japanese International Cooperation Agency, the United Nations Foundation, CDC, and other countries.

UPDATE: NUCLEIC ACID AMPLIFICATION TESTS FOR TUBERCULOSIS

MMWR. 2000;49:593-594

On September 30, 1999, the Food and Drug Administration approved a reformulated Amplified Mycobacterium Tuberculosis Direct Test* (MTD) (Gen-Probe Registered, San Diego, California) for detection of Mycobacterium tuberculosis in acid-fast bacilli (AFB) smear-positive and smear-negative respiratory specimens from patients suspected of having tuberculosis (TB). MTD and one other nucleic acid amplification (NAA) test, the Amplicorr Mycobacterium Tuberculosis Test (Amplicor) (Roche® Diagnostic Systems, Inc., Branchburg, New Jersey), previously had been approved for the direct detection of M. tuberculosis in respiratory specimens that have positive AFB smears. This notice updates the original summary published in 19961 and provides suggestions for using and interpreting NAA test results for managing patients suspected of having TB.

The appropriate number of specimens to test with NAA will vary depending on the clinical situation, the prevalence of TB, the prevalence of nontuberculous mycobacteria (NTM), and laboratory proficiency.2,3 Based on available information, the following algorithm is a reasonable approach to NAA testing of respiratory specimens from patients with signs or symptoms of active pulmonary TB for whom a presumed diagnosis has not been established.

Algorithm

1. Collect sputum specimens on 3 different days for AFB smear and mycobacterial culture.

2. Perform NAA test on the first sputum specimen collected, the first smear-positive sputum specimen, and additional sputum specimens as indicated below.

a. If the first sputum specimen is smear-positive and NAA-positive, the patient can be presumed to have TB without additional NAA testing. However, unless concern exists about the presence of NTM, the NAA test adds little to the diagnostic work-up.

b. If the first sputum is smear-positive and NAA-negative, a test for inhibitors should be done. The inhibitor test can be done as an option with Amplicor. To test for inhibitors of MTD, spike an aliquot of the lysated sputum sample with lysed M. tuberculosis (approximately 10 organisms per reaction, or an equivalent amount of M. tuberculosis rRNA) and repeat the test starting with amplification.

1. If inhibitors are not detected, additional specimens (not to exceed a total of three) should be tested. The patient can be presumed to have NTM if a second sputum specimen is smear-positive, NAA-negative, and has no inhibitors detected.

2. If inhibitors are detected, the NAA test is of no diagnostic help. Additional specimens (not to exceed a total of three) can be tested with NAA.

c. If sputum is smear-negative and MTD-positive,† additional specimens (not to exceed three) should be tested with MTD. The patient can be presumed to have TB if a subsequent specimen is MTD-positive.

d. If sputum is smear-negative and MTD-negative,† an additional specimen should be tested with MTD. The patient can be presumed not to be infectious if all smear and MTD results are negative. The clinician must rely on clinical judgement in decisions regarding the need for antituberculous therapy and further diagnostic work-up because negative NAA results do not exclude the possibility of active pulmonary TB.

3. If the indicated repeat NAA testing fails to verify initial NAA test results, the clinician must rely on clinical judgement in decisions regarding the need for antituberculous therapy, further diagnostic work-up, and isolation.

4. Ultimately, the patient's response to therapy and culture results are used to confirm or refute a diagnosis of TB.

Cautions

NAA tests can enhance diagnostic certainty, but they do not replace AFB smear or mycobacterial culture, and they do not replace clinical judgement. Clinicians should interpret these tests based on the clinical situation, and laboratories should perform NAA testing only at the request of the physician and only on selected specimens. Laboratorians should not reserve material from clinical specimens for NAA testing if this compromises the ability to perform the other established tests that have better-defined diagnostic utility and implications. Specificity of NAA tests varies between laboratories as a result of unrecognized procedural differences and differences in cross-contamination rates.4 Multiple specimens from the same patient should not be tested together to reduce risks of methodologic errors. Laboratory directors should provide to clinicians information on the performance of NAA tests in the local setting, including sensitivity and specificity compared with culture for both smear-positive and smear-negative respiratory specimens. Substantial discrepancies can indicate problems with either culture or NAA technique. The number of NAA tests repeated because of failure of negative and positive controls also should be reported. Clinicians should understand the impact that changes in sensitivity, specificity, prevalence of TB, and prevalence of other mycobacterial diseases can have on the predictive value of the NAA test. Information is limited regarding NAA test performance for nonrespiratory specimens, or specimens from treated patients. NAA tests often remain positive after cultures become negative during therapy and can remain positive even after completion of therapy.

References: 4 available

*Use of trade names and commercial sources is for identification only and does not constitute endorsement by CDC or the U.S. Department of Health and Human Services.

†Amplicor is not approved for use with smear-negative samples.

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