Influenza virus strains in Nairobi, Kenya☆

Gachara, George; Ngeranwa, J.J.N.; Magana, Japheth; Simwa, James Maylor; Wango, Peris Wairimu; Lifumo, Samwel; Ochieng, Walter

doi:10.1016/j.jcv.2005.10.004

Cited by 20 publications

(14 citation statements)

References 2 publications

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“…In the tropical zone, influenza virus circulates throughout the year, as reported in southern China, Indonesia, and Thailand (2,18,20). A laboratory-based influenza virus surveillance system has been in place in Hanoi, Vietnam, since 2001, and we have reported on the presence of influenza virus throughout the year, albeit with summer and winter peaks (21).…”

mentioning

confidence: 60%

“…As influenza viruses circulate throughout the year in the tropical and subtropical zones (18,20), the results for viruses from those areas are very suitable for monitoring purposes. This applies especially in Asia, where the emergence of new strains may be detected earlier than the emergence of new strains in temperate zones, where there is only a single peak of activity in each year.…”

Section: Discussionmentioning

confidence: 99%

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Genetic Analysis of Influenza A/H3N2 and A/H1N1 Viruses Circulating in Vietnam from 2001 to 2006

Saito

et al. 2008

J Clin Microbiol

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viruses than it did in A/H1N1 viruses. Two reassortants, one influenza A/H3N2 strain and one A/H1N1 strain, were found on the basis of the phylogenetic analysis of the three genes. While both genetic mutation and reassortment contributed to their evolution, the frequency of genetic changes and reassortment events differs between the two subtypes. As influenza viruses circulate throughout the year, we emphasize the importance of surveillance in tropical and subtropical zones, where the emergence of new strains may be detected earlier than it is in temperate zones.

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mentioning

confidence: 60%

Section: Discussionmentioning

confidence: 99%

Genetic Analysis of Influenza A/H3N2 and A/H1N1 Viruses Circulating in Vietnam from 2001 to 2006

Saito

et al. 2008

J Clin Microbiol

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“…Sporadic monitoring of influenza in other African countries has revealed outbreaks of H3N2 virus in South Africa in 2003 [28], in Madagascar in 2002 [2], and in the Democratic Republic of Congo in 2002 [2]. In addition, influenza B viruses have been reported to be circulating in South Africa, Madagascar, and Kenya [29,30]. In some of these studies, a mortality of at least 3% of cases was reported, because of influenza A/Panama/2007/97-like (H3N2) infection, indicating that influenza can have a high impact in African countries as well [2].…”

Section: Discussionmentioning

confidence: 99%

Cellular and Humoral Responses to Influenza in Gabonese Children Living in Rural and Semi‐Urban Areas

et al. 2007

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Background. With the current attention to the pandemic threat of avian influenza viruses, it is recognized that there is little information on influenza in Africa. In addition, the effects of influenza vaccination in African countries could be very different from the effects in regions with less exposure to microorganisms and parasites.Methods. To monitor the presence of influenza viruses and investigate the immunological responses to influenza vaccination, schoolchildren in semi-urban and rural regions of Gabon were studied. Influenza-specific antibody responses to the 3 strains represented in the vaccine were determined in the serum. Furthermore, cytokine responses were measured after in vitro stimulation of whole blood by influenza antigens, before and after vaccination.Results. Prevaccination titers of antibody against H3N2 were high. At vaccination, the titers of antibody against the 3 influenza strains increased significantly. The anti-H1N1 and anti-B responses after vaccination were weaker in rural schoolchildren than in semi-urban schoolchildren. Influenza-specific cytokine responses were induced within a week, showing significantly lower interferon-␥ and significantly higher interleukin-5 in the children from rural areas.Conclusions. Prevaccination antibody levels indicated that influenza viruses circulate in Gabon. Altogether, influenza vaccination induces weaker immune responses in a rural population than in a semi-urban population of Gabonese schoolchildren.

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“…Activity of influenza is reported worldwide with outbreaks during the winter season in temperate countries [1,2] . In contrast, cases of influenza in tropical countries persist all year round with peaks during the rainy season, however, epidemiological studies are still limited [3][4][5] . Recently, it was highlighted that monitoring of human influenza in Southeast Asia is important because it is where A/H3N2 first circulates before emerging worldwide and causing seasonal influenza in temperate countries [6] .…”

Section: Epidemiology Of Human Influenzamentioning

confidence: 99%

Epidemiology of Human Influenza A and B Viruses in Myanmar from 2005 to 2007

Dapat¹,

Saito²,

Kyaw³

et al. 2009

Intervirology

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Objectives: To perform genetic analysis of influenza A and B viruses in Myanmar from 2005 to 2007 and to determine the prevalence of amantadine-resistant influenza A viruses. Methods: Phylogenies of the HA and NA genes were analyzed and mutations in M2 that confer resistance to amantadine were screened. Results: Influenza in Myanmar exhibited seasonality, which coincided during the rainy season from June to August. Out of 2,618 samples, 76 influenza A and 132 influenza B viruses were isolated. Phylogenetic analysis showed that in 2005, 11 A/H1N1 isolates formed one cluster with A/Solomon Islands/3/2006 and were amantadine-sensitive strains. One A/H3N2 isolate was amantadine-resistant harboring S31N mutation in M2 and possessing S193F and D225N substitutions in HA (clade N), similar to A/Wisconsin/67/2005. No viruses were isolated in 2006 due to sample storage failure. In 2007, all 64 A/H3N2 isolates were amantadine-resistant and similar to A/Brisbane/10/2007. For influenza B, 3 Yamagata-lineage and 17 Victoria-lineage isolates were detected in 2005 and 112 Victoria-lineage viruses were isolated in 2007. All Victoria-lineage isolates were reassortants possessing NA derived from the Yamagata lineage. Conclusion: Continuous surveillance in tropical countries is important for elucidating the seasonality of influenza and determining the molecular characteristics of circulating strains.

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Influenza virus strains in Nairobi, Kenya☆

Cited by 20 publications

References 2 publications

Genetic Analysis of Influenza A/H3N2 and A/H1N1 Viruses Circulating in Vietnam from 2001 to 2006

Genetic Analysis of Influenza A/H3N2 and A/H1N1 Viruses Circulating in Vietnam from 2001 to 2006

Cellular and Humoral Responses to Influenza in Gabonese Children Living in Rural and Semi‐Urban Areas

Epidemiology of Human Influenza A and B Viruses in Myanmar from 2005 to 2007

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