Unhygienic fish could lead to tuberculosis infection
If consumed while half-cooked or when poorly handled, fish and other acquatic creatures carry germs which can cause infections in humans.
You have walked into that office and what welcomes you at the reception is the aquatic decoration. In most cases, it is fish. Some people have gone as far as taking these aquariums into their homes and you will find them placed in one of the living room corners. I must admit it is a beautiful scene watching the fish swim from one point to another either in a playful mood or in search of food.
But also because fish is a delicacy on many family meals, it has become a farming business with some people creating ponds in their home compound to make a buck out of it.
There is also this frog that keeps hopping around the house from the neighbouring waterlogged places. We are so accustomed to it that we hardly think that it could be a threat to our lives. But now scientists warn that this fish and the frogs that have become part of our home settings can be a threat to human health.
From animals to humans
For instance, Prof Robinson Ndegela, Sokoine University of Agriculture in Tanzania, says what many people do not know though, is that some fish are infected with mycobacterium marinum, which causes tuberculosis in fish and that they can easily contract this fish TB if there is no proper cleaning and cooking. The scientist also said that it has also been confirmed that some frogs have pathogens that cause brucellosis.
“There are emerging pathogens in animals in aquatic, air and terrestrial environment with detrimental emerging diseases that reduce people’s lifespan. These pathogens in aquatic animals can cause zoonotic illness,” Prof Ndegela warned.
Adding: “There is brucellosis in frogs and Tuberculosis in fish. We must be conscious about the animals we get in contact with and bring into our homes because we don’t know where these outbreaks will come from.”
Zoonotic refers to those diseases that can be passed between animals and humans. This means that if the fish or frog has the disease, they can easily transfer it to humans because of their daily contact.
His counterpart, Prof William Bazeyo of Makerere University School of Public Health, explained in an interview that the mycobacterium marinum, which causes TB can survive in fresh, warm, cold or salty water and soil for a long time. This means that the fish can get sick and stay lurking in aquariums without the aquarist or fishermen ever realising.
Reducing risk of infection
He advises people to use hand gloves when handling fish to protect them from direct contact with the fish during the cleaning process, to avoid eating roasted fish, the gills and some parts of the head like the eyes because the organisms usually hide in these internal parts. It is also important to wash hands with soap after touching fish and ensuring the fish is well cooked before eating.
“We buy fish every day. We are not even aware that fish can have TB which we can contract. If you tell somebody that you have bought fish and it could have TB, 90per cent of the people will say no because these are unknown sources of TB. Fish TB organisms usually hide in the fish internal organs and they don’t die,” Prof Bazeyo said.
He added: “Make sure the internal parts of the fish are properly removed. But we see people eating the gills and sucking the eyes. These areas are very difficult to penetrate with fire especially when you roast the fish. People who come into daily contact with fish get its mucus on their hands and fingers. They eat with unwashed hands and contaminate the food.”
Those most at risk are the fishermen, fish exporters, those who eat roasted fish and children.
Unlike beef which is tested for diseases before consumption, Prof Bazeyo said it is difficult to tell whether the fish has TB or not because there are no examinations done on fish prior to taking it to the market.
But Dr Andrew Tamale, Makerere University public expert on fish related issues asked the public to watch out for fish with nodules, wounds and those that have wasted away as some of the signs that the fish could be sick.
He added that his first study on fish diseases in Uganda was carried out in 2006 where he established that most of the diseases fish suffer from have a relationship to humans. However, there is an assumption by many people that because the fish is coming from water, it is clean.
Poor fish handling dangerous
“Fish lives in an environment that has a lot of microorganisms. Many people go to the market to buy fish and find they have wounds but continue to purchase them. They are not aware that fish can get sick. There are those wounds on the fish skin that don’t heal. This could be a manifestation that the fish is sick and people should avoid contact with such,” Dr Tamale said.
He added: “Scaling fish, swimming into the lake and ponds with wounds expose people to fish TB.”
For frogs, Prof Bazeyo explained that they spread brucellosis to humans through eating contaminated animal food like milk and meat. For instance, he added that if a cow eats grass or drinks water which has secretion from an infected frog, it will contract the illness. This is why it is advised not to eat unprepared food.
His concerns were echoed by Alhaji M. Jallow, Food and Agriculture Organization Country Representative who reported of an outbreak of brucellosis among pastoral communities in Uganda and wants scientists to investigate more about the link between such diseases and human beings.
“You know that we have communities that drink raw blood, raw milk, unpasteurised milk and raw meat and most of them are associated with outbreaks of Brucellosis,” he said.
Adding: “There is a lot of concern about tsetse fly manifestations in some parts of Uganda, a serious concern of brucellosis in parts of northern Uganda and Crimean Congo Hemorrhagic fever. We are working hard to see where it is coming from and make sure we find a situation where domestic animals are infected with it or become infected or transmission channels. These are important aspects because livestock is important to all of us.”
Brucellosis infection is usually transmitted to human beings from its reservoir by direct contact or eating contaminated food like unpasteurised milk or cheese. Research shows that more than 500,000 human cases of brucellosis are reported worldwide annually with many going undetected.
The revelations were made at a three-day International One Health conference on zoonotic diseases at Speke Resort Munyonyo under the theme; strategic approach to global health security through one health innovations vision 2035.
The World Health Organisation representative to Uganda, Dr Wondimagegnehu Alemu, said 75 per cent of diseases affecting human beings are a result of their association with animals both wild and domestic.
He attributed the re-emerging of animal-related diseases to population pressure, food insecurity, economic growth and climate change that have forced human beings to encroach on animal habitats.
“The African continent has experienced outbreaks of zoonotic diseases in the last ten years. They include Ebola, Marburg, Crimean Congo Hemorrhagic fever, Yellow fever, Rift Valley Fever, Brucellosis, plague, humans African Trypanosomiasis and Rabies,” he said.
Dr Alemu added that the recent outbreak of Ebola in West Africa was because of massive deaths of monkeys in one of the forests due to Ebola while Marburg outbreak tends to occur after a “seasonal high Viraemia in fruit eating bats”.
In the past, scientists would work in isolation.
But with these emerging diseases, they have formed a One Health Innovation approach comprising of medical doctors, veterinary doctors, agriculturalists, vector control experts, academicians, researchers and other health workers to jointly respond to epidemics for coordinated solutions.
Prof Bazeyo, Dean Makerere University School of Public Health, said their institution was chosen because of its contribution when there was an Ebola outbreak in West Africa.
Link between fish and tuberculosis
Dr Andrew Tamale explains that to tell if fish is sick, people should look out for wounds, loss of scales and loss of colour on the fish. However, he warns that some fish don’t show external signs. For instance, they could have abnormal liver and deformed spines.
Prevention
Water in the aquarium should be changed frequently to keep it fresh and add salt to the water.
If you like swimming, don’t go in that lake or river unless that wound has healed. Use protective gear when going to handle fish to avoid direct contact.
It is advised to prevent than to treat the fish disease. It is important to keep fish healthy to raise their immunity as it keeps the organisms away.
For wounded fish, it should be quarantined in a place where it can be treated.
Temperature
Although Dr Tamale says that all temperatures favour TB microorganisms, he said the ideal is between 20°C to 25°C.
Treatment
Dr Tamale warns that when you try to treat fish, you should be aware that Mycobacterium marinum can infect you as well. As such, don’t get close in case you have wounds on your body.
But once infected, the ulcers can be treated normally unless it is in advanced stages where TB symptoms in human beings start to manifest. Here, drugs that treat human TB can be used to treat Fish TB like Kanamycin. This medication should take at least three months.
