Epidemilogical and virological influenza survey in Dakar, Senegal: 1996-1998
Introduction:
Influenza (H1N1) has been known as a contagious respiratory infection with serious
consequences if not treated well. There are different stages of the influenza and every region
has different strategies or ways to control the virus. Throughout the years he influenza virus
has become more than just a virus because of the progression it has had on people, including
mortality. Because of the different symptoms and reactions the influenza virus was having on
people depending on their location, scientist wanted to be alert and more cautious.
When looking over previous influenza surveys and noticing the high rate attacks
increasing in humid seasons and tropical regions, the scientist were motivated to do this study
to prove their point. What the scientist wanted to prove was that influenza can be controlled
but it can have a higher effect depending on the seasons and location. To get more proof of the
effects of the influenza virus they chose to do a vigorous study in Dakar, Senegal; where they
conducted a survey from June 1996 – December 1998.
Materials and Methods:
To begin this survey, the scientist selected 7 sentinel sites in Dakar, Senegal: 3 in the
town center and 4 in the suburbs. Patients with influenza symptoms like: fever, sore throat,
and nasal discharge, were selected from all age groups. Scientist tested about 174 patients
weekly and separated age groups (0-14, 15-34, 35-54, ≥ 55). They recorded their ARI (acute
respiratory infections) weekly and obtained data from each patient by doing a standardized
questionnaire, collecting medical history, and clinical features.
Results:
From July 1996 – December 1998, a total of 804 patients were affected with the virus;
ages ranged from 0 – 91 years. The young age group (0 – 14 years old) had a higher effect of
the influenza virus having 59% with fevers and 2 vaccinated against the virus. When the
seasonal times hit during 1996 – 1998, 516 of the 804 patients were isolated. Virus isolations
were higher in 1997 (12.5%), 1996 (5.6%), 1998 (3.2%), and corresponded with seasons of high
rainfall, humidity and temperatures ranging from: 17.5% (1996) to 40% (1997); all 3 influenza
virus were isolated in 1998.
Discussion:
With the survey in Dakar, Senegal (June 1996 – December 1998) and data collected
during that time the scientist proved their point. “Our sentinel surveillance network has
allowed us to demonstrate the seasonal circulation of influenza virus in Dakar since 1996.
During this period, influenza-like illnesses affected all age groups” (Hannoun C, 1992)
In this survey the scientist took control of the virus and isolated it when it would take
effect; they focused and were prepared by keeping track of the symptoms when the different
symptoms came. There were no limitations on the study because they had planned out to focus
in one tropical region, gather information, and observe how the high rates of the influenza virus
affected people in all age groups. Although the scientist do wish to do another surveillance in
other tropical regions due to similar data collected in other places during the same time.
Bibliography
DOSSEH, A., NDIAYE, K., SPIEGEL, A., SAGNA, M., & MATHIOT, C. (2000). epidemiological and virological
infuenza survey in Dakar, senegal: 1996-1998. the american society of tropical medicine and
hygiene, 639-643.