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Friday, July 25, 2025

Why is the flu so dangerous?

by

2045 days ago
20191217

In­fluen­za comes from the Ital­ian words for “in­flu­ence.” It goes back to the 1500s when peo­ple did not know what caused these epi­demics of cough­ing, headache, mus­cle ache and even death. So peo­ple be­lieved their health was be­ing “in­flu­enced” by the stars.

To­day, sci­ence and tech­nol­o­gy has be­come so ad­vanced that we know that the flu is not due to the in­flu­ence of the stars, but some­thing even stranger called virus­es.

All in­fluen­za virus­es that we know about, came orig­i­nal­ly from wild bird virus­es. Not just any wild birds, but birds that are con­sid­ered to be wa­ter­fowl like chick­ens, ducks and geese or shore birds.

These birds are what we call the reser­voirs of in­fluen­za. There are bil­lions and bil­lions of these birds in the world. Many of them mi­grate and in­fluen­za virus­es cir­cu­late in them on and on­go­ing ba­sis. By and large, the virus does not harm these birds, but be­cause of their abil­i­ty to mi­grate from tem­per­ate zones to trop­i­cal zones and vice ver­sa, it al­lows the virus to spread glob­al­ly.

One may ask: how did the bird flu or in­fluen­za start af­fect­ing hu­mans?

Since an­cient times the wa­ter fowl formed a part of the di­et and even­tu­al­ly be­came do­mes­ti­cat­ed live­stock reared for their meat and eggs. Trans­mis­sion of the flu virus to hu­mans might have been as ear­ly as then. How­ev­er, with meat and egg con­sump­tion and the ex­plo­sion of hu­man pop­u­la­tion in this mod­ern time, we see the de­vel­op­ment of in­dus­tri­al scale chick­en fa­cil­i­ties which cre­ates a per­fect en­vi­ron­ment for ori­gins and spread of so-called su­per strains of the in­fluen­za virus.

There is da­ta that sup­ports as­so­ci­a­tion of an in­creased de­mand for poul­try prod­ucts and the emer­gence of vir­u­lent strains of this virus ca­pa­ble of bird to hu­man and hu­man to hu­man trans­mis­sion.

In 2009 we saw a fur­ther evo­lu­tion of this via the pan­dem­ic of swine flu or H1N1 strain of the in­fluen­za virus. This strain is thought to be a mu­ta­tion of four known strains of the in­fluen­za. The process of the emer­gence of this new strain seems to have start­ed with hu­man and birds trans­mit­ting dif­fer­ent strains of in­fluen­za to an in­ter­me­di­ate porcine hosts, name­ly pigs. Dur­ing co-in­fec­tion, dif­fer­ent seg­ments of each virus re­com­bined to form a new vi­ral strain, H1N1, that is even more vir­u­lent than the orig­i­nal par­ent vi­ral strains. This new strain spreads from pigs to hu­man through di­rect con­tact.

Nor­mal­ly, the virus is able to mu­tate in such a way be­cause of its in­ef­fi­cient repli­ca­tion and re­pro­duc­ing its ge­net­ic ma­te­r­i­al as well as com­bin­ing ge­net­ic ma­te­r­i­al from its bird, pig and hu­man hosts. Thus, its ge­net­ic ma­te­r­i­al, which de­ter­mines its sur­face struc­ture changes, and the im­mune sys­tem has to re­learn the sur­face of the virus be­fore it launch­es an im­mune re­sponse.

As a re­sult, hu­mans can nev­er be­come im­mune to the in­fluen­za virus be­cause of how it rapid­ly mu­tates. This is a key fea­ture in abil­i­ty to in­fect, cause dis­ease and even cause death.

Un­like oth­er types of com­mon­ly known virus­es that in­fect hu­mans, like measles or yel­low fever that stay ex­act­ly the same through years and decades, in­fluen­za is char­ac­terised by the abil­i­ty to mu­tate or drift. In a world like to­day when there are se­ri­ous dis­eases like Tu­ber­cu­lo­sis and Hu­man Im­mun­od­e­fi­cien­cy Virus (HIV) and Ac­quired Im­mune De­fi­cien­cy Syn­drome (AIDS), why is there so much con­cern about the in­fluen­za?

Look­ing fur­ther back, we see in 1918 an in­fluen­za pan­dem­ic trig­gered by the virus be­came the worst plague in hu­man his­to­ry. This in­fluen­za virus, which orig­i­nat­ing from birds, killed more peo­ple in 25 weeks than AIDS have killed in 25 years. Thus, in­fluen­za is the on­ly virus on the plan­et ca­pa­ble of in­fect­ing bil­lions. This has fur­ther in­creased with the pan­demics such as swine flu in mod­ern times. These pan­demics re­sults from the virus’ abil­i­ty to drift.

Every 10 years a so, a brand new form of the virus emerges that is not sea­son­al or have in­fect­ed hu­mans be­fore. An in­fluen­za pan­dem­ic is the emer­gence of an in­fluen­za virus that is to­tal­ly new. Thus, the im­pact of the virus can be much more se­vere and can re­sult in a huge num­ber of deaths.

The in­fluen­za virus af­fects the hu­man res­pi­ra­to­ry tract. When some­one has con­tract­ed in­fluen­za virus, the com­mon symp­toms are; fever, mus­cle aches, joint pains, cough, sore throat, chest pain and gen­er­al­ly feel­ing un­well. There is no cure, so pa­tients are ad­vised to treat the symp­toms con­ser­v­a­tive­ly with bed rest, in­crease flu­ids and med­ica­tion for the pain and fever, un­til the im­mune sys­tem rids the body of the virus.

There is, how­ev­er, the in­fluen­za vac­cine which is rec­om­mend­ed an­nu­al­ly. As the virus mu­tates, new vac­cines are pro­duced every year to com­bat against new strains. The shot con­fers some pro­tec­tion, how­ev­er, if one con­tracts the virus af­ter get­ting the shot, they may suf­fer less com­pli­ca­tions than if they did not have the shot. These may in­clude se­ri­ous com­pli­ca­tions, even death.

There is the an­ti-vac­ci­na­tion move­ment that ad­vo­cate against get­ting the vac­cine and oth­er scep­tics about the vac­cine. There is cur­rent­ly no sig­nif­i­cant da­ta to sup­port their claims. What is clear is that in­fluen­za caus­es se­ri­ous mor­bid­i­ty and mor­tal­i­ty an­nu­al­ly as sup­port­ed by lo­cal da­ta by the Min­istry of Health. In­di­vid­u­als who get the vac­cine have a bet­ter chance of avoid­ing the flu and its com­pli­ca­tions, even death. Get vac­ci­nat­ed now!

Dr Visham Bhimull

MBBS (UWI) Diplo­ma in

Fam­i­ly Med­i­cine (UWI)


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