I know, there are countless animals out there which are harmful to humans (in dietary context) but in this article, we are going to discuss two diseases which originated from animals. Those diseases were HIV and Creutzfeldt Jakob Disease (CJD); both of which have claimed thousands of lives throughout the history of mankind. I bet most of us are quite familiar with HIV but not CJD. Of course, we are! People are much more familiar with viruses compared to prions and acquired cases of CJD only make up for less than 1% out of the total global infectious cases.
HIVs, whichever strain they were, are parasites. Not the microorganism but rather in the context of symbiosis. They need a host to replicate themselves by utilising the transcriptional machinery available in cells or they won't thrive at all. It is difficult to pinpoint the exact origin of HIV since we have been interacting with a lot of factors that might have been the cause of infection itself throughout the years but we have some idea about it. Note that, although we have been using the word HIV to describe the disease, it is the name of the virus; Human Immunodeficiency Virus.
Sex services and illegal intravenous drug usages are not new and it was speculated in the past (now we know) that both of them are the reasons why this disease has been spreading, causing local to global scale catastrophe. This virus used to be exclusive to certain animals until it crossed the species barrier notably from chimpanzees to humans in 1920. The microbial agent responsible for this infection was only discovered in 1983 but we have no idea regarding its origin up until 1999 when we discovered a virus called the Simian Immunodeficiency Virus (SIV) which has a similar structure to HIV.
The initial presentation is quite vague and can be often mistaken for something else. For this reason, we can't say for sure if someone was infected unless they were tested for HIV antibodies and it is often associated with anxiety, depression, obsessive behaviour and doctor shopping. I used to have a little bit of chit-chat with someone who was waiting for his turn to see the doctor and he admitted the fact that he went to at least 3 doctors before getting to where he is. Even if they were tested negative, they refused to believe that. If the individual was so into the idea, they would unconsciously create symptoms and be willing to subject themselves to various tests, anything. It's called as Factitious disorder.
If you can recall, I did write about how I'm currently trying to develop an ideal medication reminder for mobile phone application for the past 1 year. Well, some of our candidates for beta testing are people who are HIV positive that have to take anti-retroviral medication for the rest of their lives to reduce viral counts. It's imperative for them to take their medication every single day to maintain an excellent immune system thus health, making it possible to achieve an equal lifespan relative to the general population.
Chimpanzees and mangabeys are two prominent animal figures in which the virus was thought to be originating from. Hunters back in the day, love to eat chimpanzees or mangabeys or pretty much anything that they can get their hands on and while doing so, any open wound or sore which might have been in contact with blood from the animals could have been the mechanism of infection; they were infected by SIV back then before the virus mutated. Mutations are bitches. Even though SIV can be considered as harmless when they inhabit the blood of simians, when it crosses to the human's blood, they started to change and attack the immune system, destroying them which would eventually lead to acquired immunodeficiency syndromes (AIDS).
AIDS is the end-game for HIV infection. Before the advent of various kind of anti-retroviral drugs, people who were diagnosed with AIDS would have a maximum 3 years to live before they would succumb to infections; the body can't seem to protect itself as their immune cells have depleted. Pneumonia, flu might be harmless for healthy adults but without a working immune system, people are going to get more than just symptoms of pneumonia (or any related diseases).
Back then, in Malaysia, public education regarding HIV is very much inadequate. This is because people who came for HIV checkup and were tested positive were often stigmatised and ostracised by the local community thus instituting fear among people to know their own HIV status. Nowadays, for those who want to get married in Malaysia, they have to take a mandatory HIV screening so that the problem can be curbed as early as possible. Treatments, counselling sessions, support groups; we have all kind of alternatives to support people with HIV to ensure they can lead a pretty much normal life but the real struggle is often internal. You know what I mean. You can give a hundred solutions for a single problem, but if someone is not motivated or they are somewhat afraid of inevitable consequences, not even a single solution can be utilised.
I Want To Eat A Squirrel, Do You Want Some?
If you are interested or currently taking psychology or psychiatric medicine as your primary subject, you would know that nihilistic delusion (detachment from reality) is usually associated with severe mental disorders such as major depressive disorder, schizophrenia etc. Some medical case reports, however, beg to differ. The diagnosis accompanying nihilistic delusion can be bizarre. In 2015, a 61 years old man was admitted with a set of bizarre symptoms (disorientation, unable to walk, nihilistic delusion) with a brain scan appearances resembling CJD. Now we know that there are at least 4 types of CJD; either you get it sporadically or you inherited it or you get it from procedures or it is a disease which is called as the bovine spongiform encephalopathy (BSE), the latter can only be acquired from eating infected meat product specifically beef.
The most prevalent type is, of course, the sporadic CJD. I'm not sure whether if it is indeed the case or we actually can't explain the pathophysiology of the variant of CJD that have been killing specific people but the majority of papers seem to support the fact that this disease progresses rather quickly, from the moment of diagnosis to death (maximum 5 years give or take). It is kinda irrelevant to pair both HIV with CJD given both of them have a different number of occurrences, one being common, the other one is quite rare. A study conducted by Hanna et al in 2013 until 2018 regarding CJD found that only 5 people throughout the 6 years of study were suspected to have CJD ( 2 of them were tested negative). That's pretty rare, don't you think?
Anyway, the 61 years old man didn't have any family member who has CJD, it might be sporadic considering 85% of all the CJD cases were but the most critical information from his medical history is that he came from a family which loves to hunt and eat whatever they can get their hands on, particularly squirrels. Even though we often gut the animals to eat their meat but some people would love to eat their brains as appetizers (or main dish, whatever). Although we know both HIV and CJD are entirely different regarding their pathophysiological features, symptoms and treatments, both of them do affect the brain of their host in some ways, so eating them can be detrimental.
One of the probable reasons why people were infected with SIV back in the 1920s, other than being exposed to the infected blood of the animals while retaining open wound, is that they might have gone for the brain (which is infected) instead. It's considered exotic, I mean there is got be a reason why a chimpanzee always go for the brain first, right? In the past, cattle are fed with food containing a concentrated protein ration which is considered a probable reason why they were infected in the first place.
The worst symptom that they (cattle) could have experienced is the inability to stand and since there is no definitive way of knowing if a cattle were infected, a significant number of them were slaughtered. Even with the most sophisticated technology now, it's tough to diagnose CJD and the most definitive conclusion can only be made after sampling a piece of the brain tissue of the host; yes, I've written it right, it can only be confirmed after the victim has died.
We can suspect people were having CJD by comparing the appearance of their brain MRI with an infected person or detecting a certain kind of protein in the cerebrospinal fluid, but as what has been documented by Hanna et al, 2 out of 5 of their subjects were tested negative (autopsy). According to a report written by the Centers for Disease Control and Prevention, up until last year, there are only 4 cases of CJD which have been reported in the United State of America (Source). One of them was suspected to have been exposed by people who were infected with the mad cow disease (BSE) before moving to the USA while the for the rest of them, the cause can never be determined.
The reason why is it essential for us to diagnose people with CJD as soon as we can even though the disease can't be treated with any kind of medication (yet) is to ensure we decontaminate any kind of surgical equipment which we might have imposed on that particular patient. The mechanism of spread for this particular disease is poorly understood and as it is deadly, we can't take any chances. The only thing we can make from all of the articles related to CJD is if you were diagnosed, the only way to make your life better is symptomatic treatments, to alleviate any kind of discomfort while waiting for a more definitive treatment to be invented.
Conclusion
Diseases which can be transmitted by animals to humans carried a significant medical value to the general population especially to a place from which its people are the most vulnerable with. Some diseases, like HIV, can be transmitted between humans via specific mechanisms such as unprotected sexual intercourse, blood transfusion with infected equipment etc. but to curb the mutation of a more resistance species, it is crucial for us to know the exact origin of that particular virus.
References: [1], [2], [3], [4], [5]
All images were taken from Pixabay
Images: [1], [2], [3], [4], [5], [6].
