Friday, May 3, 2024

Spillover by David Quammen

This book is great for those who want to understand how a spillover happens, especially considering exotic diseases, for example Ebola, HIV, SARS, etc. Spillover is a term to express the threshold of circumstances how a zoonotic disease spills to humans. The aim is to answer questions: when, where and how. It does not dig into the microchemistry or microbiology of certain hot diseases, which is good, because it does not serve the purposes in this case. It does mention some aspects of mathematical equations to forecast an epidemic, and people who invented them. Quammen has done good work to track down researchers and map information around diseases. The main focus in this book is zoonotic diseases.

Fragments or highlights I learned from this book (might contain errors, excuse my memory):

HIV originates from “southern” Cameroon. There is a monkey species which carries SIV with equilibrium state. From there, somehow the monkey has contaminated a chimpanzee population, probably a chimpanzee has eaten a monkey carrying SIV. Chimpanzees have their own epidemic of AIDS. I do not remember which thing spilled the SIV to humans, the chimpanzee or the monkey, but it is for sure that the probable explanation is during a widespread trend of bushmeat. A human has eaten some sort of bushmeat or there has been an accident during a hunt, where SIV blood has gone to a wound of a hunter. It is hard to speculate the precise event, because it is history in a jungle. It is also for sure that HIV has been around in humans since the beginning of 20th century (1908). The least probable theory is that HIV is some kind of lab product, but it is mentioned that HIV could have been spread during polio vaccines in Africa during 1950-1960, because of using expensive reusable needles and “growing” vaccines in some sort of cell culture of chimpanzees, which is contaminated. AIDS 'previous name was (suggested) GRID, Gay Related Immune Deficiency, but soon people realized that there are other routes to contaminate a body, and not only gay people, the GRID was abandoned. HIV-1 and HIV-2 have multiple groups/variations. HIV/SIV is a retrovirus, which drills into the cell dna and embeds the payload in there.

Zoonotic spillovers are a result of human “breakout”. Humans are the biggest breakout in the entire history of the earth. The biomass of people is only the latter of the biomass of livestock, which is also the result of humans. Why all these exotic killer diseases emerge is only because humans are disrupting the balance of nature. People cut down forests, spread living spaces, invade the habitat of other species, which enforces other creatures more closely to the human population. People eat almost anything in certain parts of the world. Ebola mainly spills, because somebody drags out a diseased corpse of an ape from the forest and a village will eat the whole thing. There are mines in caves, which contain habitat of bats, which contaminate the caves with guano, and miners of course get contact with these feces. Bats are probably the most common reservoirs of exotic diseases, because bats species cover ¼ of all mammal species. There are over 1600 species of bats in the world. In China, there is Wild Flavor trend, which means that people would like to eat anything they can get their hands on. In wet markets, Chinese stacks all sorts of creatures together without any regulations or responsibility, and all these excrements circulating from bats and other creatures, will create pandemics like SARS.

Some livestock farms, let say in Europe, consist for example pigs or goats. Pig is a creature, which oinks, farts and does such a heavy duty ventilation, that in a case of epidemic in the pig farm, can amplify a virus and spread the virus airborne. With certain weather conditions, the virus can travel en masse vast distances to a town or a city, causing zoonosis in the human population. Same can happen in goat farms, when goats live in certain conditions where a pathogen can gain superiority. This is again a result of human culture.

The book was written in 2012, and it tried to speculate about the next big pandemic. In the end section the speculation is around certain diseases like influenza, but it also mentions coronaviruses, which eventually happened. SARS was preceding coronavirus.

It is an absolutely great read.

Self-reflection, if that matters:

Reading the book on many bus trips to work, I often watched how grossly people actually maintain their sanitary. 6 of 10 people touch their faces at least once in that particular bus trip. At least 1 or 2 of 10 people had to constantly touch their faces. Somebody actually dug his nose, put the finger in his mouth and after that he shaked something to the ground, and next he was touching the stop button. One guy had to stroke his hair constantly, because the hair-do has to be whatever it had to be. One girl poked her eyeball with her bare finger. One guy stroked his girlfriend's hair, and his fingers were utterly brownish, probably from a filth, and the guy was the whitest caucasoid there is. I understand that it is good to have an exposure to something to maintain the resistance of the body, but there should be at least some decency. I think that this is again a feature of human breakout. I am not saying that most people are idiots, but most people certainly lack self-preservation and discretion. The thinking of causality and pure ignorance. If we think of epidemics/pandemics, the reason is purely in here. There is a reason why in local supermarkets people are standing in the middle of the corridor. There is a reason why somebody sneezes and the virus disperses in the middle of the corridor of that supermarket. There is a reason why people are walking in the middle of the corridor, wandering around not knowing that there are other people around. As the book said, evolution has no purposes, only results.