INFLUENZA- MILD/LETHAL-DR.D.K.JHA,M.D
Influenza may be seasonal during cold weather or throughtout the year as in India.
In India the highest number of cases are usually seen during rainy season.
There are three types of influenza viruses,Influenza A,B and C.
Influenza C virus usually causes mild and sporadic disease.
The particular strain H1N1 is called swine flu.
A person suffering from influenza can infect others , 24 hours before the onset of symptoms to 5 days after disappearance of symptoms.
Young children can shed virus for a longer time than adults and elderly.
Immunocompromised individual can shed virus for weeks to months.
The symptoms can appear very fast within a day or may progress overs days.
The incubation period is 1-4 days.
Immunised persons can have mild symptoms even if they get infected.
In mostof the caese ,the disease gets resolved in 3-7 days.
In few cases ,the generalised malaise and cough persist for 2 weeks or more.
Children particularly below 5 years of age, have more complications,more rates of hospitalisations,and more rates of deaths in comparision to adults.
Immunocompromised individuals may have severe disease and high chance of death due to influenza ,so they are particularly advised to get immunised.
The disease spreads through droplets from person to person, formed during coughing or sneezing.
SIGNS AND SYMPTOMS:
Running nose is less common in influenza.
Patients or Parents complaint of headache,fever which may range from 100.4dF to 104dF.
Generalised bodyache,malaise,fatigueness.
No interest in eating ,playing or working depending on age.
Pain in throat and limb pain which makes children unable to walk.
Child may suffer from diarrhoea.
Cough may be troublesome which is usually dry cough but sputum may be produced.
Nausea and vomoting are common in children.
Blocked nose may be a complaint
Chest pain may be a complaint due to pleuritis.
On examination:
child may be dull
Eyes may be red and watery
Throat may be red due to pharyngitis
There may be cervical lymphadenopathy
On chest auscultation,there may be bilateral diffuse wheezes and crackles. If the finding is localised, it indicates secondary bacterial infection.
In severe cases,there may be signs of respiratory failure.
There may be generalised muscular tenderness.
There may be signs of dehydration.
Investigations:The gold standard investigation for confirming the diagnosis is RT-PCR or culture of nasopharyngeal or Pharyngeal swab.
Chest X-Ray shows bilateral diffuse reticular opacities or bilateral diffuse patchy opacities.
If the opacity is in lobar pattern,it indicates secondary bacterial infection.
Chest X-Ray may be normal.
Complete blood count is usually normal.
TREATMENT:Treatment is usually symptomatic. Paracetamol is given for pain and fever.
Salicylate should not be given due to fear of Rye syndrome.
Neuraminidase inhibitor is the drug of choice when the disease is severe enough to be treated by antiviral.
It acts against both A and B influenza.OSELTAMIVIR is recommended for infants and children
IT SHOUD BE STARTED WITHIN 48 HOURS OF ONSET OF SYMPTOMS
DOSES: For preterm neonates-1mg/kg/dose bid ,oral
For full term neonates:
less than 14 days old 3mg/kg/dose, once daily for 5 days,oral
More than 14 days old 3mg/kg/dose, bid for 5 days,oral
INFANTS :
LESS THAN 3 MONTHS:12mg,po,bid for 5 days
3-5 months:20mg po bid for 5 days
6-11months:25 mg po bid for 5 days
CHILDREN:
Less than 5 kg weight-30mg,po,bid for 5 days
5-23 kg-45mg,po,bid for 5 days
23-40kg-60mg,po,bid for 5 days
more than 40 kg -75mg,po,bid for 5 days
ORAL SUSPENSION CONTAINS 6 mg/ml
IMMUNISATION: It is recommended for all children above 6 months of age.
Below 6 months of age they are protected by antibody from mother.
Individuals having chronic lung,liver,kidney disease and primary or secondary
immunodeficiencies are particularly advised for vaccination.
There are two types of vaccines-Live attenuated and inactivated.
Live attenuated is recommended above 2 years of age and it is given intranasally.
Inactivated vaccines are either trivalent or tetravalent.
Tetravalent have better protection for influenza B along with A.
The vaccine is updated every year as the virus changes itself rapidly due to antigenic shift and drift
property.
It should be given as early as it becomes availabe and definitely before the start of season.
It takes 10-14 days for the start of protection after vaccination.
The inactivated vaccine is given intramuscularly,0.25ml for children between 3-36 months and
0.5ml for children above 36 months.
For the first time recipient, it is given in two doses ,4 weeks apart and then single dose every year.
REFERENCES:
- Wong SS, Yuen KY. Avian influenza virus infections in humans. Chest. 2006 Jan. 129(1):156-68. [Medline].
- Swine Influenza (Flu). Centers for Disease Control and Prevention. Available at http://www.cdc.gov/swineflu/. Accessed: April 27, 2009.
- Dawood FS, Jain S, Finelli L, Shaw MW, Lindstrom S, Garten RJ, et al. Emergence of a novel swine-origin influenza A (H1N1) virus in humans. N Engl J Med. 2009 Jun 18. 360(25):2605-15. [Medline].
- Henderson, D. Influenza: Complications in 1 in 3 Previously Healthy Kids. Medscape Medical News. Available at http://www.medscape.com/viewarticle/829342. Accessed: August 4, 2014.
- Troy Brown, RN. FDA Committee Recommends 2018-2019 Influenza Vaccine. Medscape Medical News. 2018 Mar 01. Available at https://www.medscape.com/viewarticle/893314.
- Moscona A.Medical management of influenza infection.Annu Rev Med.2008;59:397-413
- Harriet Lane ,21e,2018
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