Special Sub-Topic: Don't Let the Bed Bugs Bite!
|One of the most notorious disease carrying insects is the mosquito, which can transmit several illnesses, such as malaria. What is the meaning of the word "malaria"? |
Bad air. This term comes from the belief that malaria was caught by breathing in the "bad air" from nearby swamps. This would have appeared to be true as swamps acted as mass breeding grounds for mosquitoes.
Malaria, along with yellow fever, dengue fever and other mosquito-borne diseases are often said to be transmitted by the "bite" of the insect, however, the mosquito does not technically bite, but instead stabs/pierces the skin with its proboscis. Moreover, it is only the female mosquitoes which transmit diseases to humans, as they, unlike the males, require protein from blood in order to produce eggs.
|A schistosome is a flatworm which is responsible for infecting humans with schistosomiasis. Which other invertebrate acts as a host for the schistosome eggs?|
Freshwater snails. Parasitic schistosoma enter a person's bloodstream after burrowing into the skin. The parasites migrate through the body and many of the vital organs, before reaching the liver where they will mature. Once matured, they will move to either the small intestine or the bladder, where they will produce hundreds of eggs per day whilst in their human host (up to 20 years). Some of the eggs will remain in the body, causing damage to vital organs, but some will leave in the faeces and urine of the person, which will eventually be returned to the water in which people bathe. These eggs will enter freshwater snails and will grow into the parasites capable of infecting humans, thus continuing the cycle.
|Leishmaniasis, though rarely fatal, may cause significant superficial changes to a person who becomes infected after being bitten by a sand fly. Which of these is a typical symptom of leishmaniasis? |
Large skin sores. When the female sand fly is acquiring her blood meal, protozoa of the Leishmania genus may infect her host, leading to leishmaniasis. This disease can be cutaneous, which results in the unsightly sores mentioned in the question, or visceral, which affects internal organs.
|Bites from horseflies pose the risk of infecting humans with the parasitic Loa loa (itself an invertebrate), causing filariasis. What name is commonly given to this parasite? |
The African eye worm. Loa loa actually causes subcutaneous filariasis, with symptoms limited to localised swelling and pain. Though called the African eye worm, this parasite is actually a roundworm, and can live in several parts of the body, not just the eye.
Lymphatic filariasis is another variant and can result in elephantiasis.
|Though assassin bugs rarely exceed a few centimetres in length, they are the vectors of a Central and South American disease which causes vomiting, aching, fatigue, and a characteristic swelling of the eyelids. What is the name of this disease?|
Chagas disease. After ingesting the parasite (Trypanosoma cruzi) from an infected human's blood, an assassin bug will bite another host. However, rather than passing the parasite directly into the host's bloodstream, the bug will defecate near to the site of entry, and the faeces will infect the wound.
The characteristic swelling of the eyelids is known as Romana's sign. Swelling can also affect internal organs, posing a potentially fatal threat.
|Stories of a man's struggle against death hit the headlines in 2010 after he ate a slug for a dare. The cause of the problem was the rat lungworm parasite, which caused the spinal cord and brain of the man to swell. What type of disease was this identified as? |
Meningitis. The rat lungworm parasite is a natural parasite of rats, but is often passed, via the faeces, to slugs and snails. The Sydneysider who ingested the infected slug in 2010 spent over a month in hospital, but survived the experience.
The first case of slug-borne meningitis in Sydney was reported 7 years earlier, in 2003, which was also the result of a dare. Though the men in both instances survived, there have been cases where the affected patient died after eating the slug.
|Parasites transferred by the bite of some tsetse flies can cause a disease known as sleeping sickness. Why is this disease so named?|
Because untreated patients can enter comas from which they can never be woken. Only a small proportion of tsetse flies are carriers of these parasites (Trypanosoma brucei) and the disease itself progresses very slowly. The symptoms (fever and headaches), however, gradually intensify as the parasite reproduces in the host's bloodstream.
The disease is widespread in sub-Saharan Africa and, if left untreated, usually proves to be fatal.
|The bite of the black fly can cause a person to develop onchocerciasis, also known as river blindness. What causes some of the sufferers of this disease to become blind?|
Inflammation of the eye tissue. Inflammation of the cornea (known as keratitis) is a common symptom of onchocerciasis and after the swelling subsides, the front of the eye is often left opaque, blinding the sufferer.
Another symptom of this disease is depigmentation of the skin, giving sufferers a spotted appearance.
|Guinea worms, which grow inside the bodies of small crustaceans, will cause a disease known as dracunculiasis if they manage to enter a human host. How do humans usually become infected with these parasites?|
By drinking contaminated water. Whilst the small crustaceans are killed by stomach acid, the guinea worms are able to survive and breed within their new human host. The parasites reproduce sexually and, as the smaller males die after mating, the females remain in the body for around another year, before emerging from the host's skin. The sufferer may feel nauseated, but the main trauma is the actual emergence, which is said to feel like an intense burning sensation.
|The title of this quiz echoes a common saying - "don't let the bed bugs bite". TRUE or FALSE, there have been many documented cases of diseases transmitted to humans by bed bug bites.|
f. Bed bugs are real and do tend to live in a domestic habitat. They are parasitic, possessing mouthparts capable of piercing the skin of a human and they carry several pathogens, yet there have been no documented cases of humans catching a disease from a bed bug bite.
Most of the bed bugs' feeding takes place at night, as they detect carbon dioxide emitted from their sleeping host.
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