VHFs remain a persistent public health threat: review of 2010

In the year 2010, the occurrence and spread of Viral Haemorrhagic Fevers [VHFs] in the EMR continued to represent a major and persistent threat to public health. Most of these emerging infectious disease events have involved zoonotic infectious agents. A number of countries in the Region [Please see the map] have reported VHFs in 2010 signifying an increasing risk for geographic expansion of these emerging viral threats in the Region

Domestic transmission of Rift Valley Fever virus in Diawara (Senegal) in 1998.

In 1998, circulation of the Rift Valley Fever (RVF) virus was revealed in Diawara by detection of IgM antibodies in sheep and isolation of the virus from mosquitoes caught outside a village. A seroprevalence study was carried out. Finger-prick blood samples, individual and collective details were obtained. One thousand five hundred twenty people (6 months - 83 years) were included. Overall prevalence in this group was approximately 5.2%. The prevalence in infants (6 months - 2 years) was 8.5%. Age, gender, contact with a pond, presence of sheep, and abortion among sheep, and individual or collective travel history were not statistically associated with prevalence. Prevalence increased significantly when the distance to a small ravine, located in the middle of the village, decreased. The results suggest a low, recent, not endemic circulation of the virus. Culex quinquefasciatus was captured near the ravine. This mosquito, similar to Culex pipiens, can play a similar role in human-to-human transmission of the RVF virus.

Climate-disease connections: Rift Valley Fever in Kenya

Entre 1950 e 1998 houve surtos de febre no Vale do Rift, no Quênia, após períodos de aumentos pluviométricos anormais. Em escala interanual, esses períodos estiveram associados à fase quente do fenômeno ENSO (El Niño/Southern Oscillation) na Africa Oriental. As chuvas alagam os criadouros de mosquitos - dambos -, cujos ovos, infectados pela via transovariana, eclodem, produzindo mosquitos Aedes, transmissores do vírus da febre do Vale do Rift aos seres humanos e, em especial, ao gado. A análise dos dados históricos sobre surtos de febre do Vale do Rift e indicadores do fenômeno ENSO - incluindo temperaturas superficiais dos Oceanos Pacífico e Indico e o Indice de Oscilaçäo Sul - mostrou que mais de 75 por cento dos surtos ocorreram em períodos quentes do ENSO. Na época estudada - 1981-1998 -, o mapeamento das condiçöes ecológicas via satélite (NDVI) - com dados normalizados sobre diferenças na vegetaçäo - evidenciou que as áreas de surto apresentaram desvios anômalos na intensidade do verde da vegetaçäo (indicador de pluviosidade alta), em particular, nas regiöes áridas da Africa Oriental - as mais afetadas pela febre. Os resultados indicam associaçäo estreita entre variabilidade climática interanual e surtos de febre do Vale do Rift no Quênia.

Rift valley antibodies among camels imported into Egypt

Studies were conducted to investigate the potential role of imported camels and associated ticks from sudan and Kenya as a mechanism for the introduction of arboviruses into Egypt. Blood specimens were obtained from camels in Southern Egypt on arrival from Sudan during October 1986 through October 1987 and from Kenya during 1986 for serological assays. Also, ticks were collected from camels for viral assays. Antibody to RVF virus was demonstrated by the HI test among 24% [1, 417. 5, 907] of the camels or 19% [1, 040/5, 607] from Sudan and 92% [275/300] from Kenya. Neutralizing antibody was detected in 25 of the antibody positive camels from Kenya and in 75 from Sudan. Also, antibody was demonstrated to Dhori virus by the complement fixation test in 19% [N=200] of a sample of sera, and likewise, antibody to Chikungunya [5%, N=686], West Nile [44%, N=419] and Sindbis [14%, N=419] viruses was detected by the HI test on the basis of immunofluorescent staining, Chikugunya, Sindbis and Dhori viruses were isolated from Hyalomma dromedarii ticks. These data imply that arboviruses may be spread by infected ticks associated with the movement of camels from Kenya and Sudan to Egypt