Killer bugs among us - the kissing bug and the Asian giant hornet
Humans have had a long history with bugs. In fact, bugs and the diseases they cause have been responsible for changing the course of human history. For instance, fleas carrying the Yersinia pestis bacteria caused the spread of the plague during the middle ages, known as one of the most devastating pandemics in human history.
Did you know there are over 900,000 species of living bugs? While many are harmless, some can result in serious illness and sometimes death in humans. Among the most dangerous bugs that cause harm to humans are the kissing bug and the Asian giant hornet.
Kissing bugs are so called because they typically bite near the face or mouth. They are however also known as assassin bugs, vampire bugs or conenose bugs and scientifically as triatomine bugs of the Reduviidae family.
Some kissing bugs are carriers of the parasite Trypanosoma cruzi. These bugs are blood-feeding and transmit the parasite during a blood meal. Essentially, after biting, they generally defecate near the site of the bite, and the parasite in the feces is transmitted through scratching or rubbing into broken skin.
T. cruzi causes a disease known as Chagas disease, named after the Brazilian physician Carlos Chagas who described it in 1909 (Kropf and Sá 2009). Before the disease was officially named, it is speculated that Charles Darwin may have contracted Chagas disease after being bitten by the kissing bug in Chile, as he wrote in his journal The Voyage of the Beagle in 1835.
To date, approximately 6-7 million people worldwide have Chagas disease, according to the World Health Organization. The disease was entirely confined to Latin America for several years; however, in the past decades it has been detected in the United States, Canada and some European and Western Pacific countries.
So is Chagas disease fatal? The short answer is that it can be.
T. cruzi infection is curable if treated immediately with anti-parasitic drugs such as benznidazole or nifurtimox. However, the efficacy of these drugs diminishes the longer a person has been infected. Approximately 30% of chronically infected people can develop cardiac problems and up to 10% develop digestive, neurological or mixed alterations. Approximately 12,000 deaths per year worldwide are attributed to Chagas disease (Lee et al. 2013).
Asian giant hornet
Another killer bug that can be harmful to humans is the Asian giant hornet, scientifically referred to as Vespa mandarinia. The stinger of the Asian giant hornet is approximately 6 mm long, and injects a potent venom that contains a cytolytic peptide called mastoparan that can cause tissue damage by stimulating the activity of phospholipases (Abe et al. 2000).
The venom of the Asian giant hornet also contains a neurotoxin called mandaratoxin, which can be lethal to humans at high doses. Multiple stings can deliver a lethal dose leading to renal failure, anaphylactic shock or cardiac arrest (Abe et al. 1982).
In rare cases, patients have died of multiple organ failure particularly after a relatively large number of stings (Yanagawa et al. 2009). In Japan, fatalities due to Asian giant hornet stings are estimated to range from 30-50 persons each year (Yanagawa et al. 2009).
In addition to their direct effect, Asian hornets impose threats to human existence through their impact on honey bees. These bugs are known to feed on honeybees, which are essential for pollination of many agricultural crops.
The smaller Asian hornet family member Vespa velutina is currently stirring panic in the United Kingdom since its entry into the country in September 2016 for the first time in history. The ecological impact of large amounts of V. vespa is that they can potentially impact our ability to feed ourselves if they decimate honey bee colonies, since honeybees are major pollinators.
While insects are not necessarily the deadliest animals among us, they can significantly impact human health and existence. To support further scientific understanding of insects, Bio-Rad offers some anti-insect antibodies for entomology research.