Top 10 Highlights
Bats are big carriers of a wide range of infectious diseases and are widely acknowledged as being ‘reservoir hosts’ for emerging infectious diseases that can cross species. As hosts, bats often have a stable relationship with the disease and don’t exhibit clinical signs of the infection. They live all over the world but are particularly prevalent in the tropics where they cluster in large numbers in rainforest areas where these diseases often originate. Here we compile the list of Diseases Spread By Bats.
Diseases carried by bats are spread through their droppings (guano), urine and saliva. Bat droppings form spores in dirt that can subsequently be inhaled by other animals. Bat guano and urine are spread across wide areas because bats fly. Diseases can also be transmitted by bats scratching or biting other animals or humans. Other animals can also eat fruit that has been partially eaten by bats, thereby ingesting the bats saliva.
While this all sounds pretty awful, bats are not naturally aggressive creatures. In fact many people find them to be friendly and they can even become tame in certain conditions. Just don’t let them bite you, or dribble on a cut or poo on your food.
The Australian bat lyssavirus (ABLV) is closely related to the rabies virus and, although there have been only a few cases diagnosed to date, all were fatal. In one case symptoms did not appear for almost 2.5 years after infection by a bat bite, but death occurred 19 days later.
The known cases of lyssavirus have all been in the warmer areas of northern Australia however bats with the disease have subsequently been found in the southern city of Melbourne. It is also thought possible that lyssavirus exists in some southern Asian countries such as the Philippines.
Rabies vaccine can be used to protect people who operate in at risk areas.
9. Hendra Virus
Hendra virus is from the henipavirus genus and is cousin to the nipah virus. Hendra occurs specifically along the north eastern Australian coast although henipavirus is found throughout Asia and most likely extends to Africa.
Fruit bats (flying fox) are the natural reservoirs of the hendra virus. Horses are particularly susceptible to the disease although it is still uncertain as to whether the hendra virus is transferred directly from the bat to the horse or done so via another animal (one study suggested cats are the most likely link). The humans who have been infected by hendra have all been working closely with infected horses.
Symptoms include respiratory problems in the initial phases followed by meningitis. Fatality rates are around 50% in humans and 75% in horses.
Histoplasmosis, also known as Cave’s, Darling’s or Ohio Valley disease is an infectious disease that primarily impacts the lungs and respiratory tracts of the sufferer. In chronic cases it can present like tuberculosis. The histoplasma capsulatum fungus is found in soil, often in association with bat guano or bird droppings and, if disrupted, can be inhaled.
The symptoms of histoplasmosis are often non-specific respiratory problems including coughing and other flu-like issues. In severe cases the disease affects organs other than the lungs and the fatality rate in these instances is very high.
Histoplasmosis is common around the Ohio River valley and the lower Mississippi River in the US, south and east Africa, Bengal in India and the St Lawrence River Valley in Canada.
Leptospirosis is a bacterial infection that is most often spread by animal urine or water containing animal urine that comes into contact with cuts or breaks in the skin, or is ingested. In some areas the prevalence of the bacteria mean that even swimmers, kayakers or surfers can become infected.
Mild cases of leptospriosis can be treated with antibiotics but the symptoms can be non-specific and difficult to diagnose. If left untreated this infection can cause severe respiratory problems, meningitis, renal failure and even liver failure. The more severe forms of leptospirosis are known as Weil’s disease, named after Adolf Weil who first described it in the late 1800’s.
It is estimated that up to 10 million people globally are infected by leptospirosis each year.
6. MERS Coronavirus
MERS (Middle East Respiratory syndrome) is a recent respiratory coronavirus first reported in Saudi Arabia in 2012. It has now been found in countries across the Middle East including Jordan, Qatar, Egypt, UAE, Kuwait and Oman plus Bangladesh, the Philippines, Indonesia the UK and USA. (It appears all cases are linked to the Arabian Peninsula).
250 deaths have been recorded from around 700 documented cases. Symptoms include coughing, fever and shortness of breath with more severe cases moving to pneumonia and organ failure.
MERS is understood to come from the Egyptian tomb bat although there also appear to be links to camels.
5. Marburg Virus
Marburg virus disease (MVD) is a viral hemorrhagic fever that is similar in most respects to the ebola virus. It was named after the German city of Marburg where the virus was first discovered.
Like ebola, the asymptomatic incubation phase generally last around five days but can last up to three weeks. Strong flu-like symptoms are followed by bleeding and organ failure. The average mortality rate is a little over 50% however some outbreaks, such as in Angola in 2004 (the largest outbreak seen to date with over 250 cases), saw 90% of sufferers die.
Although the first recorded cases of marburg were in Germany in 1967, there have been no further outbreaks in that country. Other outbreaks have occurred in Yugoslavia, the Netherlands, the Soviet Union, Kenya, Congo, Uganda and Angola.
4. Nipah Virus
Nipah virus is closely related to the Hendra virus, both viruses belonging to the genus Henipavirus. Flying foxes are the natural carriers of nipah and it is thought that it first crossed to humans in Malaysia where fruit trees were planted near pig farms. It was sick pigs that got the virus over to humans, but bats that transferred it to the pigs.
Other outbreaks in India and Bangladesh look like they were fuelled by fruit that was contaminated with urine or saliva from infected bats and there have been some instances of direct transfer from bat to human.
Like most of these viruses the initial symptoms are very similar to a bad case of the flu but the symptoms get worse and worse. In the case of the nipah virus neurological problems including recurring encephalitis (inflammation of the tissue around the brain) and the fatality rate exceeds 50% and can go as high as 75%. There are no effective treatments or vaccines.
3. SARS Coronavirus
The SARS virus has risen to international prominence on several occasions, impacting large numbers of people, particularly those travelling through affected areas in Asia. SARS (Severe Acute Respiratory Syndrome) has a mortality rate of about 10%, although this figure jumps for at-risk groups such as the elderly.
The symptoms of SARS include flu-like muscle pains, fever and headache followed by more severe respiratory problems including coughing and even pneumonia.
2. Ebola Virus
Ebola needs little introduction given the current spread of the disease through countries in West and Central Africa. Fruit bats naturally host the ebola virus and transmit the disease to humans where the fatality rate is as high as 90%. Once ebola passes from a bat to a human it can be spread between humans through bodily fluids.
Symptoms of this disease can appear within days of contracting the virus, however in some cases symptoms do not appear for several weeks, hence the difficulty in controlling its spread. Symptoms are initially similar to a severe flu but progress to vomiting, diarrhea and reduced functioning of the kidneys and liver. In about half the cases of ebola the patient will bleed internally, from puncture wounds such as injections sites and in rare cases, from eyes and other subcutaneous areas of skin.
There is no effective treatment or vaccine for ebola although there have been recent reports of trial vaccines working in isolated cases.
If a person who has been exposed to the rabies virus is given the post-exposure prophylaxis (PEP) vaccine early they stand an excellent chance of preventing the infection from taking hold. However once a person has been infected and begins to exhibit symptoms of the disease they will almost certainly die. Rabies has the highest fatality rate of any of these infectious diseases – close to 100%.
Rabies is a virus that causes inflammation of the brain. Fever, violent spasms, hysteria, paralysis and hallucinations follow before death. It’s a particularly nasty way to go.
More than 50,000 people die from rabies each year and while rabid dogs and cats are responsible for the majority of instances of transmission to humans, bats also carry the disease.
WARNING – this video has footage of people dying from rabies and it isn’t very nice.