Understanding the Threat of Pest-Borne Diseases

Pest-Borne Diseases are viral and bacterial illnesses spread by mosquitoes, ticks, sand flies, and other insects. Mosquitoes, for example, spread Zika virus, yellow fever, dengue hemorrhagic fever, and malaria.

Yersinia pestis is the bacteria that causes plague. Plague takes three forms in humans: pneumonic, septicemic, and bubonic. A warming climate increases the number of infections. Visit their Website for more details about pest-borne diseases.


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All people, wherever they live and travel, are vulnerable to diseases spread by mosquitoes, ticks and fleas. These insects, known as vectors, are infected with bacteria or viruses and then spread them to humans when they bite them. Almost everyone has been bitten by a mosquito and been infected with a mosquito-borne disease at some time in their life. Many of these illnesses are common and widespread, such as malaria, dengue fever, chikungunya and yellow fever, which affect tropical regions throughout the world. Others are limited to specific geographic areas or occur in particular circumstances, such as plague and trench fever.

Increasing global travel and urbanization are contributing to the spread of vector-borne diseases to new regions and countries. The Zika virus, for example, is spreading rapidly through the Americas and other parts of the world through the bite of infected Aedes aegpti mosquitoes. Malaria, caused by a single-celled organism called Plasmodium, is also spread by mosquitoes and affects all continents except Antarctica. Rocky Mountain spotted fever is transmitted to humans in the United States by American dog and Rocky Mountain wood ticks that have been infected with the bacterium Rickettsia rickettsii.

Many of these diseases can be prevented through a combination of common sense and pest control practices. Using insect repellents with an EPA label, such as DEET (N, N-diethyl-m-toluamide), when exposed to high risk habitat and peak biting conditions can reduce the chance of infection. Examining the skin and scalp for ticks and removing them promptly as soon as they are found can dramatically reduce the chances of tick-borne illness. Draining or changing standing water around the home and yard can discourage mosquitoes and other species that carry diseases, such as frogs and toads that can carry schistosomiasis.

Vaccines are available for some mosquito-borne diseases, such as dengue fever and Japanese encephalitis. Check with your healthcare provider to learn more about these vaccines and how they work. Vaccines for other diseases, including malaria, are being developed.


Insect-borne diseases are illnesses spread by mosquitoes, fleas, ticks and other arthropods (like flies, bees and hornets) that carry pathogens in their bodies. These pathogens are then transferred to humans through bites. Infection can cause disease and sometimes death, depending on the pathogen.

Mosquitoes are vectors for a large number of diseases, most of which are viral in nature. The viruses are transmitted in four groups: Bunyavirales, Flaviviridae, Togaviridae and Reoviridae. They can cause encephalitis or meningitis, with symptoms ranging from fever to neurological damage to brain inflammation.

Fleas and ticks are the main vectors for other diseases, such as malaria, Lyme disease and scrub typhus, but also for more common illnesses like babesiosis and rickettsiosis. Mosquitoes also transmit West Nile virus, chikungunya and yellow fever.

The diseases that are carried by the mosquitoes differ in symptom, transmission rate and geographical distribution. Some diseases are very serious, such as plague and malaria, while others may be more mild, such as shingles and dengue fever.

Plague (Yersinia pestis) is a serious and sometimes deadly infection that has been around for centuries. It is still seen in the world today, although not as frequently as before due to organized mosquito control and improved hygiene.

Other diseases are more widespread, such as encephalitis and meningitis. They occur throughout the world, with the greatest burden falling on Africa and the tropics of Asia and South America. These diseases can result in long term disability, economic loss and social exclusion.

Other disease-causing organisms are spread mechanically by flies, beetles and cockroaches, which pick up the organism through contact with filth, waste, and contaminated food in human environments. They then transfer the pathogen to people by ingesting it, or through faecal deposition, regurgitation and direct contact with the body. Cockroaches are particularly important in urban environments as they are prolific carriers of bacteria, fungi, protozoans and viruses, all of which can be transmitted to people by direct contact or through contaminated surfaces and food. They can also trigger allergies, asthma and dermatitis. They can be effectively controlled by sanitary measures and pesticides.


Almost everyone has been bitten by mosquitoes, ticks and fleas, which are called vectors because they carry pathogens that cause disease. The diseases spread by these pests are called vector-borne diseases. Plague, an infection caused by a bacterium (Yersinia pestis), is a classic example of a vector-borne disease. The bacteria is carried by the insect Xenopsylla cheopis, an Oriental flea that ingests Yersinia pestis during a blood meal and then transmits the bacteria to its host. Symptoms range from mild flu-like symptoms to death.

Increasing global travel and urbanization are contributing to the spread of vector-borne diseases. Reliable diagnosis is essential for preventing major production and economic losses.

Reliable diagnosis is also necessary to implement appropriate pest control strategies and practices to reduce the spread of disease. Plant health diagnostics are based on the identification of physical, chemical and biological changes in a plant during an infection. Currently, the most common methods for detecting plant infection include visual damage inspection and microbial culture tests. However, these methods are time-consuming and labor intensive, and their accuracy is limited by environmental factors.

Advances in E-nose technology can provide rapid, reliable and nondestructive plant pest detection. These devices measure volatile organic compounds, or VOCs, emitted by a plant. During infections, the composition of these chemicals change, and this information can be detected by an E-nose device. This allows for early detection of plant disease and pests, thus enabling prompt implementation of preventive measures.

VOCs are emitted by many different parts of a plant, including the leaves, stems and roots. Infection with fungi and bacteria affects the VOC profiles of plants, resulting in changes that can be detected by an E-nose. These changes can be used to detect fungal and bacterial infection in plants, as well as to discriminate damaged plants from those that are asymptomatic (no visible damage).

An emerging threat to public health is babesiosis, a group of infections caused by the Babesia protozoa. These infections, which are transmitted by the bite of ticks from the genus Ixodes, can lead to fever, fatigue and a rash. If untreated, babesiosis can result in serious, life-threatening disease in people with compromised immune systems.


Insect-borne diseases impose enormous health and economic burdens on people. Those who contract insect-borne diseases experience painful, debilitating illnesses, sometimes with life-long effects. Health systems are overwhelmed and companies that trade in products that require a high degree of hygiene suffer reputational damage when their goods are contaminated.

Infection with parasites and bacteria carried by insects cause serious illness, death and disability. The diseases often affect the poorest populations and their impact is disproportionately felt in tropical and subtropical areas. They afflict millions of people and cripple healthcare systems worldwide. Major outbreaks of dengue, malaria, yellow fever, chikungunya and Zika have affected many countries in recent years and killed thousands of people. Other infections such as sars, leishmaniasis and Chagas disease (also known as American trypanosomiasis or lymphatic filariasis) cause life-long suffering, debilitation, disfigurement and stigmatisation.

Pest-borne diseases are spread in three main ways: by bites of blood-sucking insects, through faecal transmission and through mechanical transmission. Mosquitoes, fleas and ticks spread mosquito-borne diseases such as dengue, chikungunya and yellow fever. Ticks also spread Lyme disease and Rocky Mountain spotted fever.

Flies and cockroaches do not bite, but act as passive carriers of a wide range of disease-causing bacteria, fungi, helminths, protozoans and viruses. In human environments they are present in hospitals, homes, animal sheds and markets and can be in contact with contaminated food, water, surfaces and materials. They transmit the pathogens by faecal deposition and regurgitation, and by carrying them on the surface of their bodies onto human products, foods, drink and hands.

Flies and cockroaches are also significant vectors of amoebic dysentery, spreading the organism by physical contact with faecal contamination on products and surfaces. The bacteria invade the intestines and produce large amounts of bloody diarrhoea, resulting in weight loss, extreme weakness and dehydration. The bacteria can also invade and infect other body sites, including the liver, lungs and lymph glands. Symptoms vary, but include fever, chills, headache, skin rash and sore muscles. The disease is potentially fatal in 25% of untreated cases. A vaccine is available. The plague is caused by the Gram-negative bacterium Yersinia pestis and takes on three forms: pneumonic, septicemic and bubonic. The plague was responsible for the well-known epidemics in medieval times and is now endemic in parts of Africa, Asia, Europe and South America. The most dangerous form of the disease, which is the one associated with swollen and painful lymph nodes, is usually fatal if not treated early.