Zoonotic Threat: Living with viruses

Monkeypox yet another reminder of the perils of breaking natural barriers with viruses.

Zoonotic Threat: Living with viruses
From media reports and a flurry of public health agency advisories, we have learnt that monkeypox is caused by a virus from the family of orthopox viruses. (Reuters)

Even as a protracted war in Ukraine, alarming reports on the pace of climate change, shocking school shootings in the US and depressing denial of schooling to girls in Afghanistan are vying for media space, viruses are demanding and getting global attention. Omicron is busy crafting new sub-lineages to rev up its engines of infectivity, and becoming more adept at evading the radar of acquired immunity. An adenovirus has been implicated in a rise of hepatitis in children.

Meanwhile, there are new concerns about the spread of monkeypox to several countries outside its endemic locations in Western and Central Africa.

From media reports and a flurry of public health agency advisories, we have learnt that monkeypox is caused by a virus from the family of orthopox viruses. It is similar to but less lethal than the variola virus that causes smallpox. It has a long incubation period of 5-21 days (usually 7-14 days). Apart from flu-like symptoms (fever, aches and chills), affected persons also have swollen lymph nodes. A distinctive rash appears on the skin at different locations, affecting even unusual locations like the palms of the hands and the genitalia.

Transmission happens from animals to humans and then from humans to humans. In the endemic regions of Africa, the route of transmission of the virus is through the consumption of meat from infected wild animals (bushmeat). An infected human may transmit the virus to other humans through droplets of saliva or mucus (by coughing, sneezing or spitting) or through physical contact (via touch or sexual activity). Even infected clothing or blankets can transfer the virus. The Congo Basin clade of the virus is more virulent than the milder West African variant, but the latter is the more widespread cause of the disease.

In the past fortnight, several countries in Europe, North America and West Asia have reported monkeypox infections. The virus is less adept at human-to-human transmission than the SARS Cov-2 virus and case counts are not alarming. However, much of the global alarm is because Western countries are now experiencing the thrust of the virus. African countries are pointing out the double standards of ignoring the virus when it is considered to be a peculiar problem of Africa but loudly ringing the alarm bells only when high-income Western countries are affected.

Animal-to-human transmission was reported earlier from the US, during an outbreak in 2003. It was linked to a wholesale pet store which imported animals from Africa. According to Helen Branswell (STAT, May 23), small mammals imported from Ghana included two rope squirrels, a Gambian rat and three dormice. These animals infected nearby prairie dogs at the pet store, and those animals then passed it on to humans. A total of 47 persons were infected in six US states during that outbreak.

The long incubation period, prior to onset of clinical symptoms and signs, makes airport screening ineffective in stalling the entry of infected international travellers. Contact tracing is still useful once a case is detected. An infected person must be isolated till recovery from symptoms and safe shedding of scabs. The smallpox vaccine offers cross protection and is effective for primary prevention as well as post-exposure prophylaxis after contact with an infected person. Antiviral drugs developed against smallpox are effective, but best reserved for persons with severe symptoms and immuno-compromised individuals.

India had its last case of smallpox in 1975 and stopped manufacturing the vaccine in 1979. While the generation born in India before 1979 were vaccinated against smallpox, many who were born after the virus was eradicated have not received the vaccine. Those born after 1979 will be high-priority candidates for the smallpox vaccine in areas where suspected monkeypox spread has shown up.

True to form, high-income countries are cornering global supplies of both new and old generation smallpox vaccines as well as anti-viral drugs. While many stocks of smallpox vaccine were being held by these countries even earlier—due to fears of bioterrorism—monkeypox has kicked off a new race for acquiring more vaccines.

India’s own vaccine manufacturing capacity will be increasingly called upon as viral outbreaks, such as Covid-19 and monkeypox, become global threats. Public sector vaccine manufacturing capacity must be revived, in addition to support for private manufacturers. Apart from boosting India’s ability to become the largest global supplier, public sector vaccine manufacturing units will provide a dependable option for using compulsory licences that may be issued by the government, even when private manufacturers are diffident.

While vaccines and anti-viral drugs are important aids to combat viral diseases, there are many fundamental questions we need to ponder over. Why do humans believe that we can flagrantly violate natural boundaries which keep many viruses confined to wild animals? What makes us import exotic pets from far away countries, instead of viewing them in their natural habitat, by visiting or via video? Why is it that we cannot provide food security to all people, instead of forcing non-tribals to forage for forest animals? Why is exotic meat the fad of the well-to-do? Why are forests being destroyed for ill-planned urban expansion, mining, and growing grains to feed factory-farmed cattle bred for meat? Even as we uninhibitedly feed on animal bodies, we offer our bodies to viruses for an inter-species spillover.

Only two viruses have been eradicated so far—small pox in humans and rinderpest in cattle. Most of the rest will stay on as co-habitants of this planet. So long as humans are the primary host, those viruses will not decimate humanity as they too must survive as species. Humans, with their claim of being the most intelligent species so far, must take care not to acquire viruses from their natural hosts (other animal species) or allow viruses that we acquire to recycle through the animals we infect. Otherwise, we will be playing a losing game of catchup with viruses that can mutate and multiply far faster than us. They can adapt faster than we invent. Evolutionary biology calls for co-existence with caution. No monkey business, this!

(The author, a cardiologist and epidemiologist, is president, Public Health Foundation of India (PHFI). Views are personal.)

Get live Share Market updates and latest India News and business news on Financial Express. Download Financial Express App for latest business news.

First published on: 28-05-2022 at 03:15 IST