Influenza in the tropics.

Area of Science:

• Virology
• Epidemiology
• Public Health

Background:

• Limited data on influenza in tropical countries historically.
• Avian influenza (H5N1) and the 2009 pandemic spurred research.
• Need for understanding tropical influenza epidemiology and virology.

Purpose of the Study:

• To review recent data on viral and epidemiologic aspects of influenza in tropical countries.
• To summarize findings on influenza seasonality, prevalence, and genetic diversity in the tropics.
• To assess antiviral resistance patterns in tropical influenza virus isolates.

Main Methods:

• Review of recent scientific literature on tropical influenza.
• Analysis of epidemiological data, including seasonality and prevalence.
• Examination of viral genetic diversity and phylogenetic analysis.
• Assessment of antiviral resistance data for influenza viruses.

Main Results:

• Influenza seasonality in the tropics is highly variable, with year-round circulation and distinct epidemic periods observed.
• Molecular diagnostic methods indicate influenza prevalence rates comparable to temperate regions.
• Phylogenetic analysis reveals the evolution and divergence of avian (H5N1) and human influenza strains (A/H1N1, A/H3N2, B).
• Detection of oseltamivir and zanamivir resistant influenza strains in tropical settings.

Conclusions:

• Influenza exhibits diverse seasonality in tropical countries, including year-round activity and epidemic outbreaks.
• Molecular diagnostics have standardized prevalence rate comparisons between tropical and temperate regions.
• Phylogenetic studies enhance understanding of avian and human influenza virus evolution in the tropics.
• Antiviral resistance to oseltamivir and zanamivir is present in tropical influenza viruses, despite limited drug usage.