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EID Weekly Updates

EID Weekly Updates:

Emerging and Reemerging Infectious Diseases, Region of the Americas

Vol. 1, No. 24—18 December 2003
Main Updates index

Update on Yellow Fever in the Americas

For 2003 to 6 December 2003 (Epidemiological Week/EW 49), 226 cases of jungle yellow fever (JYF) were reported to the Pan American Health Organization (PAHO), with 99 deaths. The last reported case occurred during EW 45 in the municipality of San Vicente del Caguan, Department of Caquetá, Colombia.

Two important outbreaks have occurred in the Region to this date, one in Brazil and one on the Colombian-Venezuelan border. These two outbreaks have been responsible for 82% of all reported cases. The outbreak in Brazil occurred at the beginning of 2003 in the Northeast, of the state of Minas Gerais, where 58 cases were reported. Furthermore, Brazil has reported 4 isolated cases in the state of Mato Grosso. The last case reported in Brazil occurred in EW 36, in the state of Pará, Municipality of Gurupá. The case-fatality rate of JYF in Brazil was 36%.

The occurrence of cases on the Colombian-Venezuelan border was initially detected during the last two weeks of 2002 and the first 10 weeks of 2003, in the department of Norte del Santander in Colombia and in Zulia state in Venezuela. After 11 weeks without case reports, during EW 23 new cases started to be diagnosed in the departments of Norte del Santander and Cesar in Colombia. At the same time, on the other side of the border, Venezuela reported cases in the states of Zulia, Táchira, and Portuguesa. The last case of this outbreak was reported in EW 43 in Norte del Santander, Colombia. Colombia also reported isolated cases in the departments of Caqueta, Casanare, Guaviare, and Meta. As of EW 49, according to probable place of infection, 101 cases were reported in Colombia and 34 cases in Venezuela. The case-fatality rates in Colombia and Venezuela were 44% and 41%, respectively.

To date, Perú has reported 22 cases of JYF. The reports were of isolated cases or small outbreaks located in the departments of Cuzco, Madre de Dios, Puno and San Martín. The case-fatality rate was 59%, and the last reported case occurred in EW 34.

Bolivia reported 6 isolated cases, with 4 deaths, in the departments of Beni, Cochabamba, La Paz, and Santa Cruz. The last case occurred during EW 13. The case-fatality rate was 67%.

The widespread distribution of Aedes aegypti in the Americas, coupled with the occurrence of extensive outbreaks of JYF, has brought about a risk of reurbanization of the disease. To prevent the occurrence of outbreaks and reurbanization, enzootic countries should implement all the conclusions and recommendations of the PAHO Technical Advisory Group on Vaccine Preventable Diseases (TAG) as well as implement sustainable plans for vector control (document in Spanish).

Table 1: Jungle Yellow Fever, Reported Cases and Deaths
(by country, Region of the Americas, to 18 December 2003)

País Cases Deaths
Bolivia 6 4
Brazil 63 23
Colombia 101 45
Perú 22 13
Venezuela 34 14
Total 226 99
Source: Reports to PAHO by the Ministry of Health of the respective countries.

For additional information, see the following:

Severe Acute Respiratory Syndrome (SARS) in Taiwan

Public-health authorities in Taipei have reported to WHO a single case of infection with SARS-CoV in a senior research scientist. The infection appears to have been acquired in the laboratory. The researcher had travelled to Singapore earlier and became ill the day he returned to Taiwan.

A full investigation is currently underway into the circumstances surrounding the acquisition of infection and of the laboratory procedures. The results have been confirmed in multiple samples in two other laboratories in Taipei. As recommended by WHO (Summary of the Discussion and Recommendations of the SARS Laboratory Workshop, 22 October 2003 ), before such results can be considered as fully confirmed, they should be verified by an external laboratory in the WHO International Network of SARS Reference Laboratories.

All contacts are being traced and will be followed up on by the health authorities. For aditional information, see the press release issued by the Ministry of Health of Taiwan.

The WHO guidelines used to safely handle SARS-CoV specimens during the outbreak period are described in the WHO Biosafety Guidelines for Handling of SARS Specimens.. The guidelines take into account the absence of chains of human transmission and highlight the importance of strict adherence to biosafety procedures and practices in laboratory work with SARS-CoV.

Source: WHO SARS page. Geneva: World Health Organization (WHO).

Update on West Nile Virus in Mexico

Up to 10 December 2003, 591 people underwent serological tests for WNV in 25 states. Six people have shown positive results: four in Chihuahua, one in Sonora, and another in Nuevo León. Three of the cases were classified as severe disease—West Nile encephalitis or meningitis—and the other three were classified as mild disease, or West Nile Fever. Out of 29 states collecting equine samples, viral activity was detected in 22 of them. A total of 2,475 equine samples and 2 dead horses showed positive results. Viral circulation among birds was detected in 9 out of 10 states that carried out serological tests for WNV. The results showed 117 positive cases out of 17,963 tests. Also, four dead birds were found in Sonora, Tamaulipas, Tabasco, and Nuevo León and showed positive results.

Initial phylogenetic studies in Mexico indicate that the isolated virus is related to strains from the central United States but has a relatively high degree of sequence divergence. This suggests that the virus could have been evolving elsewhere for several years.

Sources

Fifth National Conference on West Nile Virus in the United States

The Fifth National Conference of West Nile Virus in the United States, organized by the American Society for Microbiology and the Division of Vector-Borne Infectious Diseases of the Centers for Diseases Control and Prevention (CDC), will be held in Denver, Colorado, from 2 to 5 February 2004.

The Conference will deal with WNV surveillance, clinical and epidemiological studies on transmission and treatment, virology, biology and ecology, laboratory diagnosis and vector control, among other issues.

Information on registration is available via the conference Website.