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Deep Learning Technology: Sebastian Arnold, Betty van Aken, Paul Grundmann, Felix A. Gers and Alexander Löser. Learning Contextualized Document Representations for Healthcare Answer Retrieval. The Web Conference 2020 (WWW'20)
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A robovirus is a zoonotic virus that is transmitted by a rodent vector (i.e., "ro"dent "bo"rne).
Roboviruses mainly belong to the Arenaviridae and Hantaviridae family of viruses. Like arbovirus ("ar"thropod "bo"rne) and tibovirus ("ti"ck "bo"rne) the name refers to its method of transmission, known as its vector. This is distinguished from a clade, which groups around a common ancestor. Some scientists now refer to arbovirus and robovirus together with the term ArboRobo-virus.
Rodent borne disease can be transmitted through different forms of contact such as rodent bites, scratches, urine, saliva, etc. Potential sites of contact with rodents include habitats such as barns, outbuildings, sheds, and dense urban areas. Transmission of disease through rodents can be spread to humans through direct handling and contact, or indirectly through rodents carrying the disease spread to ticks, mites, fleas (arboborne.
For a person or companion animal to acquire a tick-borne disease requires that that individual gets bitten by a tick and that that tick feeds for a sufficient period of time. The feeding time required to transmit pathogens differs for different ticks and different pathogens. Transmission of the bacterium that causes Lyme disease is well understood to require a substantial feeding period.
For an individual to acquire infection, the feeding tick must also be infected. Not all ticks are infected. In most places in the US, 30-50% of deer ticks will be infected with "Borrelia burgdorferi" (the agent of Lyme disease). Other pathogens are much more rare. Ticks can be tested for infection using a highly specific and sensitive qPCR procedure. Several commercial labs provide this service to individuals for a fee. The Laboratory of Medical Zoology (LMZ), a nonprofit lab at the University of Massachusetts, provides a comprehensive TickReport for a variety of human pathogens and makes the data available to the public. Those wishing to know the incidence of tick-borne diseases in their town or state can search the LMZ surveillance database.
Ticks tend to be more active during warmer months, though this varies by geographic region and climate. Areas with woods, bushes, high grass, or leaf litter are likely to have more ticks. Those bitten commonly experience symptoms such as body aches, fever, fatigue, joint pain, or rashes. People can limit their exposure to tick bites by wearing light-colored clothing (including pants and long sleeves), using insect repellent with 20%–30% DEET, tucking their pants legs into their socks, checking for ticks frequently, and washing and drying their clothing (in a hot dryer).
Mosquito-borne diseases, such as dengue fever and malaria, typically affect third world countries and areas with tropical climates. Mosquito vectors are sensitive to climate changes and tend to follow seasonal patterns. Between years there are often dramatic shifts in incidence rates. The occurrence of this phenomenon in endemic areas makes mosquito-borne viruses difficult to treat.
Dengue fever is caused by infection through viruses of the family Flaviviridae. The illness is most commonly transmitted by Aedes aegypti mosquitoes in tropical and subtropical regions. Dengue virus has four different serotypes, each of which are antigenically related but have limited cross-immunity to reinfection.
Although dengue fever has a global incidence of 50-100 million cases, only several hundreds of thousands of these cases are life-threatening. The geographic prevalence of the disease can be examined by the spread of the Aedes aegypti. Over the last twenty years, there has been a geographic spread of the disease. Dengue incidence rates have risen sharply within urban areas which have recently become endemic hot spots for the disease. The recent spread of Dengue can also be attributed to rapid population growth, increased coagulation in urban areas, and global travel. Without sufficient vector control, the dengue virus has evolved rapidly over time, posing challenges to both government and public health officials.
Malaria is caused by a protozoan called Plasmodium falciparum. P. falciparum parasites are transmitted mainly by the Anopheles gambiae complex in rural Africa. In just this area, P. falciparum infections comprise an estimated 200 million clinical cases and 1 million annual deaths. 75% of individuals afflicted in this region are children. As with dengue, changing environmental conditions have led to novel disease characteristics. Due to increased illness severity, treatment complications, and mortality rates, many public health officials concede that malaria patterns are rapidly transforming in Africa. Scarcity of health services, rising instances of drug resistance, and changing vector migration patterns are factors that public health officials believe contribute to malaria’s dissemination.
Climate heavily affects mosquito vectors of malaria and dengue. Climate patterns influence the lifespan of mosquitos as well as the rate and frequency of reproduction. Climate change impacts have been of great interest to those studying these diseases and their vectors. Additionally, climate impacts mosquito blood feeding patterns as well as extrinsic incubation periods. Climate consistency gives researchers an ability to accurately predict annual cycling of the disease but recent climate unpredictability has eroded researchers’ ability to track the disease with such precision.
A canine vector-borne disease (CVBD) is one of "a group of globally distributed and rapidly spreading illnesses that are caused by a range of pathogens transmitted by arthropods including ticks, fleas, mosquitoes and phlebotomine sandflies." CVBDs are important in the fields of veterinary medicine, animal welfare, and public health. Some CVBDs are of zoonotic concern.
Many CVBD infect humans as well as companion animals. Some CVBD are fatal; most can only be controlled, not cured. Therefore, infection should be avoided by preventing arthropod vectors from feeding on the blood of their preferred hosts. While it is well known that arthropods transmit bacteria and protozoa during blood feeds, viruses are also becoming recognized as another group of transmitted pathogens of both animals and humans.
Some "canine vector-borne pathogens of major zoonotic concern" are distributed worldwide, while others are localized by continent. Listed by vector, some such pathogens and their associated diseases are the following:
- Phlebotomine sandflies (Psychodidae): "Leishmania amazonensis", "L. colombiensis", and "L. infantum" cause visceral leishmaniasis (see also canine leishmaniasis). "L. braziliensis" causes mucocutaneous leishmaniasis. "L. tropica" causes cutaneous leishmaniasis. "L. peruviana" and "L. major" cause localized cutaneous leishmaniasis.
- Triatomine bugs (Reduviidae): "Trypanosoma cruzi" causes trypanosomiasis (Chagas disease).
- Ticks (Ixodidae): "Babesia canis" subspecies ("Babesia canis canis", "B. canis vogeli", "B. canis rossi", and "B. canis gibsoni" cause babesiosis. "Ehrlichia canis" and "E. chaffeensis" cause monocytic ehrlichiosis. "Anaplasma phagocytophilum" causes granulocytic anaplasmosis. "Borrelia burgdorferi" causes Lyme disease. "Rickettsia rickettsii" causes Rocky Mountain spotted fever. "Rickettsia conorii" causes Mediterranean spotted fever.
- Mosquitoes (Culicidae): "Dirofilaria immitis" and "D. repens" cause dirofilariasis.
The U.S. Centers for Disease Control and Prevention (CDC) publishes a journal "Emerging Infectious Diseases" that identifies the following factors contributing to disease emergence:
- Microbial adaption; e.g. genetic drift and genetic shift in Influenza A
- Changing human susceptibility; e.g. mass immunocompromisation with HIV/AIDS
- Climate and weather; e.g. diseases with zoonotic vectors such as West Nile Disease (transmitted by mosquitoes) are moving further from the tropics as the climate warms
- Change in human demographics and trade; e.g. rapid travel enabled SARS to rapidly propagate around the globe
- Economic development; e.g. use of antibiotics to increase meat yield of farmed cows leads to antibiotic resistance
- Breakdown of public health; e.g. the current situation in Zimbabwe
- Poverty and social inequality; e.g. tuberculosis is primarily a problem in low-income areas
- War and famine
- Bioterrorism; e.g. 2001 Anthrax attacks
- Dam and irrigation system construction; e.g. malaria and other mosquito borne diseases
The arboviruses have expanded their geographic range and infected populations that had no recent community knowledge of the diseases carried by the "Aedes aegypti" mosquito. Education and community awareness campaigns are necessary for prevention to be effective. Communities are educated on how the disease is spread, how they can protect themselves from infection and the symptoms of infection. Community health education programs can identify and address the social/economic and cultural issues that can hinder preventative measures. Community outreach and education programs can identify which preventative measures a community is most likely to employ. Leading to a targeted prevention method that has a higher chance of success in that particular community. Community outreach and education includes engaging community health workers and local healthcare providers, local schools and community organizations to educate the public on mosquito vector control and disease prevention.
Carrión's disease, or Oroya fever, or Peruvian wart is a rare infectious disease found only in Peru, Ecuador, and Colombia. It is endemic in some areas of Peru, is caused by infection with the bacterium "Bartonella bacilliformis", and transmitted by sandflies of genus "Lutzomyia".
Cat scratch disease occurs worldwide. Cats are the main reservoir of "Bartonella henselae", and the bacterium is transmitted to cats by the cat flea "Ctenocephalides felis". Infection in cats is very common with a prevalence estimated between 40-60%, younger cats being more commonly infective. Cats usually become immune to the infection, while dogs may be very symptomatic. Humans may also acquire it through flea or tick bites from infected dogs, cats, coyotes, and foxes.
Trench fever, produced by "Bartonella quintana" infection, is transmitted by the human body louse "Pediculus humanus corporis". Humans are the only known reservoir. Thorough washing of clothing may help to interrupt the transmission of infection.
A possible role for ticks in transmission of "Bartonella" species remains to be elucidated; in November 2011, "Bartonella rochalimae", "B. quintana", and "B. elizabethae" DNA was first reported in "Rhipicephalus sanguineus" and "Dermacentor nitens" ticks in Peru.
Sylvatic plague is an infectious bacterial disease caused by the bacterium "Yersinia pestis" that primarily affects rodents such as prairie dogs. It is the same bacterium that causes bubonic and pneumonic plague in humans. Sylvatic, or sylvan, means 'occurring in wildlife,' and refers specifically to the form of plague in rural wildlife. Urban plague refers to the form in urban wildlife.
It is primarily transmitted among wildlife through flea bites and contact with infected tissue or fluids. Sylvatic plague is most commonly found in prairie dog colonies and some mustelids like the black-footed ferret.
Sylvatic plague is most commonly found in prairie dog colonies; the flea that feeds on prairie dogs (and other mammals) serves as the vector for transmission to the new host.
The term waterborne disease is reserved largely for infections that predominantly are transmitted through contact with or consumption of infected water. Trivially, many infections may be transmitted by microbes or parasites that accidentally, possibly as a result of exceptional circumstances, have entered the water, but the fact that there might be an occasional freak infection need not mean that it is useful to categorise the resulting disease as "waterborne". Nor is it common practice to refer to diseases such as malaria as "waterborne" just because mosquitoes have aquatic phases in their life cycles, or because treating the water they inhabit happens to be an effective strategy in control of the mosquitoes that are the vectors.
Microorganisms causing diseases that characteristically are waterborne prominently include protozoa and bacteria, many of which are intestinal parasites, or invade the tissues or circulatory system through walls of the digestive tract. Various other waterborne diseases are caused by viruses. (In spite of philosophical difficulties associated with defining viruses as "organisms", it is practical and convenient to regard them as microorganisms in this connection.)
Yet other important classes of water-borne diseases are caused by metazoan parasites. Typical examples include certain Nematoda, that is to say "roundworms". As an example of water-borne Nematode infections, one important waterborne nematodal disease is Dracunculiasis. It is acquired by swallowing water in which certain copepoda occur that act as vectors for the Nematoda. Anyone swallowing a copepod that happens to be infected with Nematode larvae in the genus Dracunculus, becomes liable to infection. The larvae cause guinea worm disease.
Another class of waterborne metazoan pathogens are certain members of the Schistosomatidae, a family of blood flukes. They usually infect victims that make skin contact with the water. Blood flukes are pathogens that cause Schistosomiasis of various forms, more or less seriously affecting hundreds of millions of people worldwide.
Long before modern studies had established the germ theory of disease, or any advanced understanding of the nature of water as a vehicle for transmitting disease, traditional beliefs had cautioned against the consumption of water, rather favouring processed beverages such as beer, wine and tea. For example, in the camel caravans that crossed Central Asia along the Silk Road, the explorer Owen Lattimore noted, "The reason we drank so much tea was because of the bad water. Water alone, unboiled, is never drunk. There is a superstition that it causes blisters on the feet."
Waterborne diseases can have a significant impact on the economy, locally as well as internationally. People who are infected by a waterborne disease are usually confronted with related costs and not seldom with a huge financial burden. This is especially the case in less developed countries. The financial losses are mostly caused by e.g. costs for medical treatment and medication, costs for transport, special food, and by the loss of manpower. Many families must even sell their land to pay for treatment in a proper hospital. On average, a family spends about 10% of the monthly households income per person infected.
The list below shows the main diseases that can be passed via the fecal–oral route. They are grouped by the type of pathogen involved in disease transmission.
"A. phagocytophilum" is transmitted to humans by "Ixodes" ticks. These ticks are found in the US, Europe, and Asia. In the US, "I. scapularis" is the tick vector in the East and Midwest states, and "I. pacificus" in the Pacific Northwest. In Europe, the "I. ricinus" is the main tick vector, and "I. persulcatus" is the currently known tick vector in Asia.
The major mammalian reservoir for "A. phagocytophilum" in the eastern United States is the white-footed mouse, "Peromyscus leucopus". Although white-tailed deer and other small mammals harbor "A. phagocytophilum", evidence suggests that they are not a reservoir for the strains that cause HGA. A tick that has a blood meal from an infected reservoir becomes infected themselves. If an infected tick then latches onto a human the disease is then transmitted to the human host and "A." "phagocytophilum" symptoms can arise.
"Anaplasma phagocytophilum" shares its tick vector with other human pathogens, and about 10% of patients with HGA show serologic evidence of coinfection with Lyme disease, babesiosis, or tick-borne meningoencephalitis.
Treatment of infections caused by "Bartonella" species include:
Some authorities recommend the use of azithromycin.
About 14 million people, mainly children, are treated annually for head lice in the United States alone. Only a small proportion of those treated, however, may have objective evidence of an extant infestation. High levels of louse infestations have also been reported from all over the world including Denmark, Sweden, U.K., France and Australia.
Normally head lice infest a new host only by close contact between individuals, making social contacts among children and parent child interactions more likely routes of infestation than shared combs, brushes, towels, clothing, beds or closets. Head-to-head contact is by far the most common route of lice transmission.
The United Kingdom's National Health Service, and many American health agencies, report that lice "prefer" clean hair, because it's easier to attach eggs and to cling to the strands.
Head lice ("Pediculus humanus capitis") are not known to be vectors of diseases, unlike body lice ("Pediculus humanus humanus"), which are known vectors of epidemic or louse-borne typhus ("Rickettsia prowazekii"), trench fever ("Rochalimaea quintana") and louse-borne relapsing fever ("Borrelia recurrentis").
Waterborne diseases are diseases caused by pathogenic microorganisms that most commonly are transmitted in contaminated fresh water. This is one particular type of fecal-oral transmission.
Neglected tropical diseases also contains many diseases transmitted via the fecal-oral route.
No serious long-term effects are known for this disease, but preliminary evidence suggests, if such symptoms do occur, they are less severe than those associated with Lyme disease.
Cat-scratch disease has a worldwide distribution, however it is a nonreportable disease in humans and therefore public health data on this disease is inadequate. Geographical location, present season and variables associated with cats (such as exposure and degree of flea infestation) all play a factor in the prevalence of Cat-scratch disease within a population. In warmer climates, the incidence of Cat-scratch disease is more prevalent during the fall and winter months. The higher rate of Cat-scratch disease during those months may be attributed to the breeding season for adult cats, which allows for the birth of kittens". B henselae," the bacterium responsible for causing Cat-scratch disease, is more prevalent in younger cats [less than one year old] than it is in adult cats.
To determine recent incidence of Cat-scratch disease in the United States, the Truven Health MarketScan Commercial Claims and Encounters database was analyzed in a case control study from 2005-2013. The database consisted of healthcare insurance claims for employees, their spouses, and their dependents. All participants were under 65 years of age, from all 50 states. The length of the study period was 9 years and was based off 280,522,578 person-years; factors such as year, length of insurance coverage, region, age, and sex were used to calculate the person-years incidence rate to eliminate confounding variables among the entire study population. 13,273 subjects were diagnosed with Cat-scratch disease, both in and outpatient cases were analyzed. The study revealed an incidence rate of 4.5/100,000 outpatient cases of Cat-scratch disease. For inpatient cases, the incidence rate was much lower at 0.19/100,000 population. Incidence of Cat-scratch disease was highest in 2005 among outpatient cases and then slowly declined. The Southern states saw the most significant decrease of incidence overtime. Mountain regions have the lowest incidence of this disease because fleas are not a common vector found in these areas.
Distribution of Cat-scratch disease among children aged 5-9 were of the highest incidence in the analyzed database, followed by woman aged 60-64. Incidence among female patients was higher than that among male patients in all age groups. According to data on social trends, women are more likely to own a cat over men; which supports higher incidence rates of this disease in women. Risk of contracting Cat-scratch disease increases as the number of cats residing in the home increases. The number of pet cats in the United States is estimated to be at 57 million. Due to the large population of cats residing in the United States, the ability of this disease to continue to infect humans is vast. Laboratory diagnosis of Cat-scratch disease has improved in recent years, which may support an increase in incidence of Cat-scratch disease in future populations.
Pediculosis is an infestation of lice (blood-feeding ectoparasitic insects of the order Phthiraptera). The condition can occur in almost any species of warm-blooded animal (i.e. mammals and birds), including humans. Although "pediculosis" in humans may properly refer to lice infestation of any part of the body, the term is sometimes used loosely to refer to "pediculosis capitis", the infestation of the human head with the specific head louse.
No human vaccine is currently available for any tick-borne disease, except for tick-borne encephalitis. Individuals should therefore take precautions when entering tick-infested areas, particularly in the spring and summer months. Preventive measures include avoiding trails that are overgrown with bushy vegetation, wearing light-coloured clothes that allow one to see the ticks more easily, and wearing long pants and closed-toe shoes. Tick repellents containing DEET (N,N, diethyl-m-toluamide) are only marginally effective and can be applied to skin or clothing. Rarely, severe reactions can occur in some people who use DEET-containing products. Young children may be especially vulnerable to these adverse effects. Permethrin, which can only be applied to clothing, is much more effective in preventing tick bites. Permethrin is not a repellent but rather an insecticide; it causes ticks to curl up and fall off the protected clothing.
Human granulocytic anaplasmosis (HGA) is a tick-borne, infectious disease caused by "Anaplasma phagocytophilum", an obligate intracellular bacterium that is typically transmitted to humans by ticks of the "Ixodes ricinus" species complex, including "Ixodes scapularis" and "Ixodes pacificus" in North America. These ticks also transmit Lyme disease and other tick borne diseases.
The bacteria infect white blood cells called neutrophils, causing changes in gene expression that prolong the life of these otherwise short-lived cells.
Body lice are spread through prolonged direct physical contact with a person who has them or through contact with articles such as clothing, beds, bed linens, or towels that have been in contact with an infested person. In the United States, body lice infestations are rare, typically found mainly in homeless transient populations who do not have access to bathing and regular changes of clean clothes. Infestation is unlikely to persist on anyone who bathes regularly and who has at least weekly access to freshly laundered clothing and bedding.
Although louse-borne (epidemic) typhus is no longer widespread, outbreaks of this disease still occur during times of war, civil unrest, natural or man-made disasters, and in prisons where people live together in unsanitary conditions. Louse-borne typhus still exists in places where climate, chronic poverty, and social customs or war and social upheaval prevent regular changes and laundering of clothing.
For the most part, the chigoe flea lives 2–5 cm below the sand, an observation which helps explains its overall distribution. The temperature is generally too hot for the larvae to develop on the surface of the sand and the deeper sand does not have enough oxygen. This preferred ecological niche offers a way to decrease transmission among humans by investing in concrete grounds as opposed to the sand that is usually used in shacks and some favelas. Indeed, Nany et al. (2007) report that "In shacks with concreted ground being cleaned every day with water, Tunga [penetrans] larvae were hardly found."
In a longitudinal study conducted from March 2001 to January 2002, incidence of tungiasis was found to vary significantly with the local seasons of an endemic community in Brazil. In particular, the study found that "occurrence of tungiasis varies throughout the year and seems to follow local precipitation patterns. Maximum and minimum prevalence rates differed by more than a factor of three." The authors suggest that the correlation is due to the high humidity in the soil impairing larval development during the rainy season, as well as the more obvious reason that rain may simply wash away all stages of "T. penetrans" due its small size of 1mm.
Acting as both biological vectors and definitive hosts, humans have spread "Tunga penetrans" from its isolated existence in the West Indies to all of Latin America and most of Africa via sea travel. Since the chigoe flea technically has no reservoir species and the female will cause tungiasis to any mammalian organism it can penetrate, this means the flea will have a relatively large number of hosts and victims. Epidemiologically, this is important as tungiasis often causes secondary infections.