Thursday, July 4, 2019

Resurgence of diphtheria in India: Time to act

Dr KK Aggarwal

Recently in a meeting, young doctors of Federation of Resident Doctors Association (FORDA) expressed their concern about the resurgence of diphtheria in Delhi. They are the first point of contact with the patients and can talk about real-life situations they come across.

Last week Delhi reported its first death as per an Indian Express report. It is unfortunate that as doctors we get this information from the media. It is the duty of the public health detective in the National Centre for Disease Control (NCDC) to report and issue an alert.

Source of the first case should be traced and surrounding areas issued an alert.

Despite the introduction of mass immunization, diphtheria continues to play a major role as a potentially lethal infectious disease in many countries and 4530 cases were reported worldwide in 2015. Unfortunately, 2365 (52.2%) of these were from India.

Remember, diphtheria is an infectious disease and the primary modes of spread are close contact with infectious material from respiratory secretions (direct or via airborne droplet) or from skin lesions.

Humans are the only known reservoir for Corynebacterium diphtheriae. Therefore, asymptomatic carriers are important in diphtheria transmission. Immunity (either via natural infection or vaccine induced) does not prevent carriage. In areas of endemicity, up to 5% of healthy individuals may have positive pharyngeal cultures.

The WHO Vaccine Preventable Diseases Monitoring System has also reported periodic resurgence in India. The number of cases has been 39231 in 1980, 1326 in 1997, 8465 in 2004, 2525 in 2012, 6094 in 2014 and 2365 in 2015. Again in 2016, 2017 and 2018, the numbers rose successively to 3,380, 5,293 and 8,788.

As per Central Bureau of Health Intelligence, during 2005-2014, India reported 41,672 cases of diphtheria (average 4,167 per year) with 897 deaths (case fatality ratio 2.2%). Ten of the states (Andhra Pradesh, Assam, Delhi, Gujarat, Haryana, Karnataka, Nagaland, Maharashtra, Rajasthan, and West Bengal) accounted for 84% of the cases reported across the country.

According to successive National Family Health Survey reports, the coverage of 3 primary doses of DPT vaccine has been significantly lower than the desired goal of >90%; 51.7% in 1993, 55% in 1999, 55.3% in 2006 and 78.4% in 2016.

After the advent of widespread vaccination against diphtheria, circulation of toxigenic strains has reduced, resulting in decline in immunity in older age groups and increased susceptibility.  This age shift has been demonstrated in studies from West Bengal, Southern India, and Delhi.

Reasons for high case fatality include inconsistent and restricted availability of antitoxin and delay in diagnosis.

Delay in the specific therapy of diphtheria may result in death and, therefore, accurate diagnosis of diphtheria is imperative.

A study carried out at NCDC has shown persistence of toxigenic C. diphtheriae in our community indicating the possibility of inadequate immunization coverage. 

What should be done?
Resurgence of infectious diseases such as diphtheria is a reflection of our public systems. Instead of adding more Dunmore vaccines under pressure from GAVI, one should ensure full coverage of the traditional ones as a starter. Gavi currently supports 13 life-saving vaccines. 

Dr KK Aggarwal
Padma Shri Awardee
President Elect Confederation of Medical Associations in Asia and Oceania   (CMAAO)
Group Editor-in-Chief IJCP Publications
President Heart Care Foundation of India
Past National President IMA

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