Bats and Public Health

27-08-2020

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Bats and Public Health

Bats can be found almost anywhere in the world except the polar regions and extreme deserts. Bats can be found almost anywhere in the world except the polar regions and extreme deserts.

Bats are closely related to humans and hence they are responsible for the spread of many diseases from animals to man. Viruses that are mainly transferred this way are known as Zoonotic viruses. Inaccurate accounts of bats can cause public antipathy to the point that bats can be harmed or destroyed.

Microbes found in bats or guano fall in to several groups. They consist of bacteria, fungi, mycotic agents and viral agents. Bats also carry an array of endo- and ecto-parasitic organisms. They can be protozoan parasites, parasitic flat-worms and round worms and arthropod parasites.

Bacterial Diseases

Leptospira

A number of human and livestock disease causing bacteria have been found in bats, but the extent to which these pose an epidemiologic public health threat is unknown. Salmonella which causes typhoid and related diseases has been found in several Phyllostomid bats and also in Molossus major. Several individuals of an Australian species of Pteropus were fatally infected with Salmonella typhimurium. It is proven experimentally that the plague causing bacteria could infect Nyctalus noctula have been infected experimentally in the laboratory. Bovine type bacilli are found in several captive individuals of the Indian fruit bat. Mycobacterium can also be found in the livers of Mexican free -tailed bat. Mycobacterium causes tuberculosis and leprosy. Several species of Leptospira have been reported from pteropodids and a handful of vespertilionid bats.

Relapsing fever is caused by several varieties of Borrelia recurrentis. A number of species of Borrelia have been isolated in bats.

Fungal Diseases

[A little brown bat showing signs of fungal infection.]

Mycotic disease shared by bats and man appears to be histoplasmosis, a respiratory disease caused by inhaling spores of Histoplasma capsulatum. Histoplasmosis is a disease contracted by Mexican guano diggers in the past. Meningitis can be caused by spores of Cryptococcus neoformans found in dusty guano deposits. A new species of Yeast like fungus, Candida chiropterorum, has been described from the organs of Mormoops megalophylla, Desmodus rotundus, and Natalus tumidirostris from Colombia. Another non- pathogenic species, Candida parapsilosis, has been recovered from the liver of a Leptonycteris sanborni in Southwestern United States. Torulopsis glabrata, a common fungus of skin and mucus membranes of humans, was also found in Leptonycteris. Dermatophytes [ringworm agents] have been found on several bat species of the New World, Great Britain and western Europe.

Public health concern arises in areas where large groups of bats occupy human dwellings.

Viral Diseases

[Ebola virus found in bats].

Bats are infected by a wide variety of viruses. The virology of bats is confounded by the fact that most bats are small in size and blood serum samples are too small to permit extensive study. The colonial habits of many bat species provide a highly efficient arena for the transmission of viruses from bat to bat. Many of the viruses encountered in bats are not often pathogenic. Transmission of viruses happen from bat to bat by biting or sucking Arthropods, through aerosol suspension in the atmosphere of poorly ventilated roosts or casual bites inflicted during aggressive activity that occurs among densely crowded individuals. Many bat viral agents occur in localized areas of the world. Chikungunya virus [Asia and Africa], Rio Bravo virus [South Western United States], Japanese B encephalitis virus [Western Asia], Mount Suswa Bat Virus [Kenya], Tacribe virus [Trinidad], Montana myotis leucoencephalitis virus [Montana] etc. are a few examples of this. Uninfected bats become infected when they feed on infected mosquitoes. Many viruses are capable of overwintering in hibernating bats.

Rabies virus is found everywhere in the world except Great Britain, Australia, Hawaii and other Pacific islands. The Vampire bats are important vectors of rabies virus. If a bat bites or scratches you, wash the area and seek medical advice.

Vampire Bat feeding on livestock

Annual cattle mortality rate is too high, there are direct costs and costs due to indirect losses including malnutrition. The rabies virus has been detected in 26 out of 40 insectivorous species.

[Close-up of bite on girl’s head showing typical concave lesion]

One in every 1000 bat has rabies in America. Rabies virus has also been reported in several insectivorous bats from Germany, Yugoslavia, Turkey and possibly Hungary.

[Typical bite on the ankle of a cattle.].

Nipah Virus

Corona Virus Pandemic and bats

Research shows that one of the closest known ancestors of the virus that causes Covid-19 emerged in bats more than 40 years ago.

The missing link can be the scaly, ant-eater like animals known as Pangolins for SARS-CoV-2 transmission between bats and humans.

Protozoan parasites

Many protozoan organisms have been found as natural parasites of bats. Few chiropteran protozoan parasites are known to be harmful to man or to domestic animals. Most of these protozoans are transmitted mechanically by way of an intermediate insect vector such as a mosquito, kissing bug, or fly.

A number of malarial parasites [Plasmodium, Hepatocystis, Nycteria, etc.] are found in bats. Chagas disease is caused by T. cruzi and many bat species have been found to harbour cruzi-like parasites.

Trypanosoma-Wikipedia

Vampires are infected when they take a blood meal from an infected victim. The trypanosome then reproduces in the vampire bat Desmodus rotundus.

Arthropod parasites

Bats are parasitized by wide array of ectoparasitic arthropods. Many of these parasites such as bat flies and various groups of mites are associated with several bat species. Bat mites may find their way on to humans under situations where bats occupy human dwellings or when humans intrude in to bat roosts. The displaced mites may bite their accidental hosts and their bites may cause reactions like dermatitis and very rarely undiagnosed diseases.

References;

1] Bats

Hill J.E. & Smith J. D.(1984), Bats: A Natural History.

2] Images Retrieved from:

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