Zoonotic diseases-influenza, Biology

Influenza
Influenza is an acute infectious disease caused by influenza viruses of genus Orthomyxovirus in family Orthomyxoviridae. The name Influenza is derived from an Italian phrase which means influenced. There are 3 types of influenza viruses distinguished by their capsid proteins as Type A, B and C. It is characterized by a short incubation period followed by fever, cough, coryza and headache. It occurs in endemic, epidemic and pandemic forms. Pandemics of the disease have been recorded periodically in the world. Noted among them are pandemics of 1781, 1889, 1918 and  1957. During the 1918 pandemic, 20 million people were believed to have died from the disease in the world. The 1957 epidemic was equally extensive although the mortality was much less.

Epidemiology: Influenza is an international disease and occurs in all countries. It occurs in several forms. Epidemics usually occur at an interval of 2-3 years in case of influenza A and 4-6 years in case of influenza B. Epidemics of influenza A viruses are usually more widespread and more severe than those of influenza B. Influenza C virus usually produces inapparent infections.The incidence is highest in the age group of 5- 9 years. It gradually declines with increasing age. Mortality is common among very young and very old. Epidemics are common from early fall to late spring.Of the 3 influenza viruses, type A occurs in man, animals and birds. It causes infection in pigs, horses, turkey and other birds. Infection in some of these animals preceded human infection. It is an indication of the zoonotic nature of the infection.


Avian influenza (AI), also known as ‘fowl plague’ is also caused by type A strains of the influenza viru.


Clinical features:
Infection occurs mainly as droplet. In man the disease is characterized by a febrile illness lasting for 3-4 days and accompanied with cough and respiratory symptoms. The disease may be complicated by secondary bacterial infections. The infection may remain subclinical or latent in human as well as in the animal population.Clinical features in animal are mainly those of respiratory system involvement (for details see Chapter 19). Death in case of HPAI is usually by multiple visceral organ failure as the virus may affect the respiratory, digestive and nervous system.

Prevention and control: Prevention can be done by vaccination and strict sanitary practices. Continuous antigenic drifting of the virus poses difficulties for involving suitable immunizing means against the infection. Immunization against one type or subtype does not afford complete protection against others. Although vaccine is available, the duration of immunity is very short.


Recently a crude bird flu vaccine for poultry against the highly pathogenic avian influenza has been developed at the High Security Animal Disease laboratory (HSADL), ICAR, Bhopal. Control of LPAI is also very important as it may mutate at any time to HPAI. Biosecurity to any infectious disease should be the first line of defense. Improved surveillance to estimate the spread of disease, immediate destruction and disposal of infected and exposed birds, strict quarantine and movement control, total ban on marketing of slaughter birds from infected farms must be enforced and decontamination to remove and reduce the virus are the important preventive measures to reduce the risk of transmission of influenza from birds.

Posted Date: 9/20/2012 1:55:43 AM | Location : United States







Related Discussions:- Zoonotic diseases-influenza, Assignment Help, Ask Question on Zoonotic diseases-influenza, Get Answer, Expert's Help, Zoonotic diseases-influenza Discussions

Write discussion on Zoonotic diseases-influenza
Your posts are moderated
Related Questions
What is natural selection? Natural selection is the method by which organisms that have certain favorable traits are better capable to survive and make successfully than organi

What group did reproduction via sexual exchange of genetic information originate in?

Explain about the IMViC Test? IMViC test is a combination of four tests: (1) Indole production (2) Methyl Red test (3) Voges Proskauer, and (4) Citrate Utilization

Rice milling Rice milling involves the following processing steps: rough rice (paddy rice) → hull removal  →  brown rice  → polishing to remove the bran coats (fruits and seed

What are the two divisions of the angiosperms? The angiosperms are separated into monocotyledonous and dicotyledonous. (These categories are defined later in this text.) Pla

Q. Enlist the various modalities available for sterility assurance? Various modalities available for sterility assurance are a) Prevention of overloading b) Chemical indi

Heifers As efficient reproductive performance is essential for economic livestock production, the female calves must grow rapidly to attain sexual maturity, ovulate and be mated b

How does the contraceptive diaphragm work? What are the limitations of this contraceptive method? The contraceptive diaphragm is an artifact made of latex or plastic that when

Drowning: Drowning is a cause of accidental death  in children Accidental drowning may occur because children  do not  have adequate protective supervision.  It may be defined

Salmonellosis is the most reported zoonotic disease in European countries. Salmonellosis (Salmonella gastroenteritis) results from the ingestion of foods that contain significant n