Eight Animals That Can Transmit Deadly Diseases to Humans

Bats

Bats are natural carriers or vectors of several zoonotic pathogens including rabies, severe acute respiratory syndrome (SARS), Henipavirus and possibly even ebola virus. Rabies is mostly transmitted through direct physical contact with its victim, but it is also possible for the bat rabies virus to infect humans through airborne transmission. According to the World Health Organization (WHO) bat rabies has emerged as a public health problem in the Americas and Europe in the past few years. For the first time in 2003, more people in South America died from rabies caused by wildlife, particularly bats, than from dogs. Rabies is a viral neuroinvasive disease that causes inflammation in the brain; deadly if left untreated.

Birds

Birds can be carriers of diseases such as psittacosis, salmonellosis, campylobacteriosis, the avian tuberculosis, bird flu, giardiasis and cryptosporidiosis. Some of these can be transmitted to humans, the avian influenza or bird flu posing the most serious health threat. Just like “swine flu, “dog flu and human flu,” bird flu refers to an illness caused by any of the various strains of influenza viruses. Health experts are concerned that co-existence of flu viruses of birds and humans will create a new virulent influenza strain that can be easily transmissible and deadly to humans. When an outbreak started in 2003, at least 200 people had died in Indonesia, Vietnam, Laos, Romania, China, Turkey and Russia due to the highly pathogenic Influenza A virus subtype H5N1.

Dogs

Dogs may be man’s best friend but in many parts of the world rabies from dog bites poses a serious threat to human lives especially children.  According to the WHO, an estimated 31,000 people die from dog rabies in Asia annually; in Africa, the yearly death toll is 24,000. Rabies caused by dog bites is responsible for more than 14 million course of post-exposure treatment worldwide to prevent the onset of disease. Up to 60% of dog bite victims are children below 5 years old. Rabies can also be caught by eating rabid dog meats. Once the symptoms of the disease develop, rabies can be deadly. Dogs can also transmit toxocariasis in humans, which can cause blindness and human hookworm.

Fleas

Aside from creating itching sensation problems to animals and humans by the creature itself, fleas can be a route of transmission for diseases. These tiny wingless insects can transmit the bubonic plague to humans by carrying the Yersinia pestis bacteria. Black Death or Bubonic Plague, the most renowned and one of the deadliest pandemic in history that caused a global population reduction by almost a quarter in the 1400s was brought about by fleas from rats. Murine typhus (endemic typhus) and sometimes even Hymenolepiasis (tapeworm) can also be transmitted to humans by fleas.

Flies

Leishmania is a parasitic protozoa responsible for the disease leichmaniasis which is spread through sandflies of the genus Phlebotomus in Europe, Asia and Africa and of the genus Lutzomyia in the Americas and Austrasia. Leishmaniasis currently affects 12 million people in 88 countries. There are four main types of the disease ranging from skin ulcers which usually heals within a few months to swelling of the spleen and liver and anemia which if left untreated can have a 100% fatality rate within two years. Only the female sand fly is usually responsible for the biting and sucking the blood of mammals, reptiles and birds as she needs the protein in the blood to make her eggs. Another parasitic disease called Human African trypanosomiasis or sleeping sickness, endemic in some regions of Sub-Saharan Africa is transmitted by the bite of a tsetse fly. It is also fatal if left untreated.

Mosquitoes

Mosquitoes are vectors of disease-causing viruses and parasites from person to person without catching the disease themselves. Yellow fever and dengue fever, both transmitted by the Aedes aegypti and Malaria brought by the Anopheles mosquitoes are of primary concern. Every year, mosquitoes are estimated to transmit disease to more than 700 million people in Africa, South America, Central America, Mexico and much of Asia with millions resulting to death. Most of the diseases are carried by the female mosquitoes. Other mosquito-transmitted viral diseases includes: Eastern equine encephalitis, Japanese encephalitis and West Nile virus.

Pigs

Pigs carry a wide range of parasites and diseases that can be transmitted to humans including Trichinosis, Taeniasolium, cysticercosis, brucellosis, ascarid worms and swine influenza. Health experts are concerned that pigs may allow animal viruses such as influenza or Ebola reston to infect humans more easily. The 2009 swine influenza outbreak is due to H1N1, a new strain of influenza not previously reported in pigs. Analysis suggested it’s a re-assortment of two strains of swine influenza virus (SIV). Since April 2009, 1,061 people were infected with the swine flu worldwide with 26 reported to have died.

Ticks

Ticks are ectoparasites that live by feeding on the blood of mammals, birds and occasionally reptiles and amphibians. They transmit several diseases to humans, including Lyme disease and Tick-borne meningoencephalitis. Lyme disease or borreliosis is an infectious disease with early and late skin manifestations plus nervous system, heart, eye and joint problems. Tick-borne encephalitis is a viral infection of the central nervous system with 10-12,000 cases reported annually in Russia and Europe. The disease is fatal in 1.2% of cases and leaves 15-20% of its survivors with permanent brain damage.

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