Border Cross

International borders are meaningless to infectious diseases such as Yellow Fever

Date of Event: July 19th 2014

The tatty card with its leaden yellow shade lay submerged under various other travel documents at the bottom of my rugged rucksack, falling within eyeshot as the Impala brought us closer to the border of Kenya and the United Republic of Tanzania. Through the dust-laden windshield I could make out the anticipating ‘Rolex’ and ‘D&G’ floggers surrounding the white block-buildings of the Immigration Offices dominating the horizon.

I had made few acquaintances on this corrosive leg from the bustling centre of Nairobi; my temporary companions preferring the solace of internal reflections on earlier travels, taking time out only to frown disapprovingly at the radio’s irregular chirrups, stubbornly camouflaging their frustrations through tight lips.

Finally, I surfaced the Yellow Fever certificate, feeling it appropriate to exclaim to my neighbour with an “Aha – got it!” as if to drive the achievement home with raised eyebrows.

She turned leftwards towards me, her eyes distracted for a fraction on what I imagined to be one of the many hopeful junk-food sellers beginning to stir around our slowing, battered grey shuttle-bus.

I am not entirely certain but perhaps my neighbour was called ‘Helen’, with a heavy interest in architecture having spent most of the preceding journey engrossed in a tome of odd archaeological digs, using the rest of the time to muse on her dreams for her PhD in the subject, due to start soon in the United Kingdom. If the friends I have made in recent years are anything to go by, her PhD ambitions have probably altered more times than the Daily Mail has ran an absurd, fear-mongering piece on Ebola, since we had said our goodbyes.

Staring at the yellow document, wedged between the finger and thumb of my right hand, neither she nor I knew exactly its’ importance in our fate for the upcoming border-cross.

“I’m not even sure we need it” doubted Helen, as she fumbled to stash her book away in a rucksack in far better condition than mine.

On the converse I positioned myself on the ‘would need it’ camp, albeit without much confidence. My tentative response, however, made me feel ashamed given my education in microbiology. I bullied myself into thinking I should know the significance of this virus in all countries.

We eventually stepped out of the vehicle to join our equally hesitant fellow travellers, hovering awkwardly on the hardened mud amongst a littering of Fanta and Coca-Cola labels which can be found in even the most rural places of east Africa, before donning a strut of self-importance towards the arches of the Immigration Office.

A short wait later, lengthened only by the sweat induced moaning of our foreign congregation, I dutifully presented my passport and thumb to the Official; a smartly dressed Tanzanian woman whose soft spoken voice was all the more difficult to hear on the other side of the glass shield. I expected my yellow fever certificate to be summoned from the safety of my left pocket at any moment.

It never came.

“The Yellow Fever Certificate. Do you want to check it?” I asked in a regretfully, almost offensive, toiled manner.

She smiled back at me as I began to move my left hand towards my pocket. “OK, thank you, next please!”

I stood for a moment, feeling the glare of other travellers through the back of my head to get a move on.

“Why the indifference?” I wondered.

As I trudged onwards, placing the passport in safe retreat, I recalled the significance of the Yellow Fever Virus, a single strand of ribonucleic acids capable of manipulating the cells its’ human hosts to cause a blood bursting fever, or a discolouration of the skin and eyes, giving credence to its’ name. Some people know it as “Yellow Jack” from the days where yellow flags on ships signified a quarantine status, disrupting the trade between the Western hemisphere and coastal regions of West Africa at the close of the 19th century.

Back then, nobody knew exactly what caused the disease, although it was noted how recovery conferred with long lasting defence; from what we now understand to be the result of our adaptive immune response.

Sir Patrick Manson, in his Manual of Diseases of Warm Climates, referred only to a “germ or virus” but based on observations considered an external period from a human host for the agent to be infectious. This ‘transmission’ proved to come at the mercy of Aedes aegypti mosquitos, who live their ephemeral existence seeking constant replenishment from the crimson blood of tree-top monkeys or unsuspecting humans, occasionally spreading the virus between these hosts.

Our awareness covers only a snapshot of the scourges the virus has caused. Philadelphia, the once capital of the United States, lost almost 10% of its population at the hands of Yellow Fever Virus in 1793. It’s victims, since the first days of the virus’ discovery, across endemic regions of Middle – and South – America, and sub-Saharan African countries such as Kenya and Tanzania, will measure in multitudes of millions.

Scientists and health workers are heavily reliant on numbers. Our infatuation with statistics and percentages helps to reduce death and illness to a mere succession of digits, void of humanistic value. Just one year before I was born to a nurse and engineer in a modern and well equipped City-hospital in the middle of England, 5 million people, primarily across the tropics, faced a showdown with Yellow Fever Virus and its’ offering of doom. Supportive care is the only way to aid the human body to overcome this infectious agent’s inclination to wreak havoc on liver and blood cells. Today, people are still vulnerable, albeit in much lesser numbers. My arrival into a country of seasons and widely accessible vaccines placed my life at an almost negligible risk of dying from Yellow Fever. Serendipity and the ingrained habits of a mosquito will mean that approximately 270,000 inhabitants of the continent I had flown into, would not be so lucky within the next 12 months.

It makes perfect sense to contextualise this dramatic reduction in global deaths from Yellow Fever, with the knowledge that vaccine coverage since 1998 has increased by 46%. Such a public health feat owes much to the Nobel Prize winning efforts of Max Theiler, for his development of what was to be named vaccine ‘17D’. Derivatives of this universal standard encompass the world-wide available vaccines today, and has aided scientists to understand more about other viruses such as Dengue Virus and Japanese Encephalitis Virus, which belong to the same ‘family’ of viruses (flaviviridae). The molecular ‘backbone’ to 17D has aided the development of ‘chimeric’ vaccines, which could be useful in tackling Dengue fever. The principles behind the inception of the Yellow Fever vaccine are as important now as 80 years ago.

And yet the Immigration Official, protected by her glass pane and armed, but admittedly day-dreaming security personnel, couldn’t give two winks as to whether I had bothered to reduce mine and others’ chances of falling victim to Yellow Fever or not. Perhaps she spent too long looking at my pathetic and anxious expression, like all the other Caucasian (or in my case – a little Asian) border-hoppers whom she had already spent her energy on that day. Maybe it was my unnerving Kamikaze-like passport photo that cheered her to shoe me on without further interrogation. Or maybe Yellow Fever simply was not a big deal any more, to her or to her country.

I traipsed closer to the chugging, undulating engine of the Impala shuttle bus as if to announce a readiness to leave, in what was geographically now the United Republic of Tanzania. I turned my head towards Helen who followed in close pursuit and gestured my vaccine certificate towards her, its’ colour in forgiving contrast to that of the mid-day African sun.

“She didn’t even ask me….” I mumbled disappointedly.

I set myself up for part two of the voyage, headed towards the mountains of Arusha in northern Tanzania. As I watched the brown-haze of dust kick from alternating convoys and nodded without retention to Helen’s architectural reflections, my thoughts fell back to the smart Official; hoping she might pay an indirect tribute to Max Theiler and global vaccination efforts by summoning the card of another traveller, intending to cross the border that day.

aedes aegypti mosquito

The vector of Yellow Fever Virus: Aedes aegypti mosquito

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