Vectors Of Infectious Diseases Research Articles

Wolbachia transinfection in Aedes aegypti: a potential gene driver of dengue vectors.

The endosymbiotic bacteria in the genus Wolbachia are capable of inducing a wide range of reproductive abnormalities in their hosts, including cytoplasmic incompatibility (CI), which could lead to the replacement of uninfected host populations with infected ones. Because of this, Wolbachia have attracted considerable interest as a potential mechanism for spreading disease-blocking transgenes through vector populations. Here we report the establishment of double Wolbachia transinfection by direct adult microinjection of Wolbachia from naturally double-infected Aedes albopictus to Aedes aegypti, the most important mosquito vector of infectious viral diseases, and a mosquito in which natural Wolbachia infections are not known to occur. We further demonstrate that incomplete CI is induced in these double-transinfected mosquitoes. Comparisons of fitness traits between naturally uninfected and transinfected Ae. aegypti lines indicated one significant difference in favor of the latter, namely, an increased number of eggs laid. Levels of CI expression corresponded to the Wolbachia density. There were large differences in relative Wolbachia density between reproductive and nonreproductive tissues in both Ae. albopictus and transinfected Ae. aegypti, except Malpighian tubule, which implied the preferred establishment of Wolbachia within reproductive tissue. Results from a simulation model confirm that population replacement by transinfected Ae. aegypti is possible over time. The establishment of Wolbachia double infections in Ae. aegypti by direct adult microinjection and the demonstration of CI expression in this new host suggest that Wolbachia could be experimentally transferred into vector species and could also be used as a gene-driving system to genetically manipulate vector populations.

Identification and characterization of 17 microsatellite primers for the tick, Ixodes ricinus, using enriched genomic libraries

Abstract Ixodes ricinus is the main vector for important infectious diseases in both humans and in animals. Microsatellite loci were isolated from a dinucleotide‐enriched library made from I. ricinus sampled in Norway. Seventeen polymorphic microsatellites were further characterized among 24 individuals sampled from an island in the Oslofjord region. The number of observed alleles ranged from two to 17 and the observed heterozygosities between 0.10 and 0.83. Analysis of family materials gives evidence of non‐Mendelian inheritance of several of the characterized loci, among which most could be explained by presence of null alleles.

Multiple Pruritic Papules From Lone Star Tick Larvae Bites

Ticks are the second most common vectors of human infectious diseases in the world. In addition to their role as vectors, ticks and their larvae can also produce primary skin manifestations. Infestation by the larvae of ticks is not commonly recognized, with only 3 cases reported in the literature. The presence of multiple lesions and partially burrowed 6-legged tick larvae can present a diagnostic challenge for clinicians. We describe a 51-year-old healthy woman who presented to our clinic with multiple erythematous papules and partially burrowed organisms 5 days after exposure to a wooded area in southern Kentucky. She was treated with permethrin cream and the lesions resolved over the following 3 weeks without sequelae. The organism was later identified as the larva of Amblyomma species, the lone star tick. Multiple pruritic papules can pose a diagnostic challenge. The patient described herein had an unusually large number of pruritic papules as well as tick larvae present on her skin. Recognition of lone star tick larvae as a cause of multiple bites may be helpful in similar cases.

Acaricide efficiency of amitraz / cypermethrin and abamectin pour-on preparations in game

The efficacy of an amitraz / cypermethrin pour-on preparation (1 % w/v each) was tested against natural tick infestations of buffaloes, eland and blesbok in three separate trials. The eland were also treated with a 0.02 % abamectin (w/v) acaricidal pour-on preparation. The amitraz / cypermethrin pour-on was effective against Amblyomma hebraeum, Rhipicephalus evertsi evertsi, Rhipicephalus appendiculatus and Hyalomma marginatum rufipes on the buffaloes. Both acaricides were effective against R. appendiculatus and Rhipicephalus (Boophilus) decoloratus in the eland. The amitraz / cypermethrin acaricide was effective against R. (Boophilus) decoloratus in the blesbok. Ticks can cause damage to the skins, secondary infections, abscesses, anaemia, loss of condition, tick toxicosis and act as vectors of infectious diseases. Introduction of hosts and / or ticks from endemic to non-endemic areas because of translocation of game, may lead to severe losses. The pouron acaricides tested were effective against natural tick infestations and should always be used according to the manufacturer's instructions and efficacy claims.

Acaricide efficiency of amitraz / cypermethrin and abamectin pour-on preparations in game

The efficacy of an amitraz/cypermethrin pour-on preparation (1% w/v each) was tested against natural tick infestations of buffaloes, eland and blesbok in three separate trials. The eland were also treated with a 0.02% abamectin (w/v) acaricidal pour-on preparation. The amitraz/cypermethrin pour-on was effective against Amblyomma hebraeum, Rhipicephalus evertsi evertsi, Rhipicephalus appendiculatus and Hyalomma marginatum rufipes on the buffaloes. Both acaricides were effective against R. appendiculatus and Rhipicephalus (Boophilus) decoloratus in the eland. The amitraz/cypermethrin acaricide was effective against R. (Boophilus) decoloratus in the blesbok. Ticks can cause damage to the skins, secondary infections, abscesses, anaemia, loss of condition, tick toxicosis and act as vectors of infectious diseases. Introduction of hosts and/or ticks from endemic to non-endemic areas because of translocation of game, may lead to severe losses. The pouron acaricides tested were effective against natural tick infestations and should always be used according to the manufacturer's instructions and efficacy claims.

Containment of Arthropod Disease Vectors

Effective containment of arthropod vectors of infectious diseases is necessary to prevent transmission of pathogens by released, infected vectors and to prevent vectors that escape from establishing populations that subsequently contribute to increased disease. Although rare, past releases illustrate what can go wrong and justify the need for guidelines that minimize risks. An overview of recommendations for insectary facilities, practices, and equipment is provided, and features of four recently published and increasingly rigorous arthropod containment levels (ACLs 1-4) are summarized. ACL-1 is appropriate for research that constitutes the lowest risk level, including uninfected arthropods or vectors that are infected with micro-organisms that do not cause disease in humans, domestic animals, or wildlife. ACL-2 is appropriate for indigenous and exotic arthropods that represent a moderate risk, including vectors infected or suspected of being infected with biosafety level (BSL)-2 infectious agents and arthropods that have been genetically modified in ways that do not significantly affect their fecundity, survival, host preference, or vector competence. ACL-3 is recommended for arthropods that are or may be infected with BSL-3 infectious agents. ACL-3 places greater emphasis on pathogen containment and more restricted access to the insectary than ACL-2. ACL-4 is intended for arthropods that are infected with the most dangerous BSL-4 infectious agents, which can cause life-threatening illness by aerosol or arthropod bite. Adherence to these guidelines will result in laboratory-based arthropod vector research that minimizes risks and results in important new contributions to applied and basic science.

Tick-borne rickettsial diseases: emerging risks in Europe

Ticks are currently considered the main vectors of human infectious diseases in Europe, particularly since their role in the transmission of the agent of Lyme borreliosis was demonstrated in the 1980s. In the recent years, ticks have also been shown to be the vectors of numerous emerging rickettsial diseases. Although Mediterranean spotted fever (MSF) due to Rickettsia conorii was thought for a long time to be the only tick-borne rickettsial disease prevalent in Europe, five more spotted fever rickettsiae have been described as emerging pathogens in the last decade. Further, cases of infection due to Anaplasma phagocytophilum, the agent of human anaplasmosis (previously known as human granulocytic ehrlichiosis), have been reported throughout Europe. We present here these emerging diseases and discuss other potential threat for the future.

The Public Health Implications of Global Warming

IN 1861 THE NATURAL PHILOSOPHER JOHN TYNDALL MADE THE PREDICtion, little noted at the time, that anthropogenic emissions of carbon dioxide would trap the radiative energy of the sun within the earth’s atmosphere and raise surface temperatures. An early investigation of this “greenhouse effect” concluded that a “large-scale geophysical experiment” began ever since the Industrial Revolution wed civilization to fossil fuels. The recent data of several international consortia show that global warming is accelerating at a rate far greater than that predicted a century ago and is due in large part to combustion of fossil fuels. This issue of MSJAMA brings together several lines of published evidence that global warming has emerged as a public health challenge requiring serious, concerted action. Jonathan Patz and Mahmooda Khaliq survey the immediate threats posed by climate change as well as some of the more insidious ones. Kent Bransford and Janet Lai find grounds for a common approach to both climate change and air pollution. Stephen Liang and colleagues describe technologies that can help track the spread of climate-sensitive infectious disease vectors. Finally, William Burns discusses public policy tools to respond and adapt to these challenges. Unfounded alarmism has no place either in clinical practice or in the legislative process. On the other hand, we cannot simply ignore extensive, peer-reviewed data on the causes and impacts of climate change. Lending a sense of urgency to this seemingly distant and abstract threat may well require us to link its consequences to our quality of life. In the absence of domestic leadership on global warming, one way to accomplish this goal might be to summon health care professionals to nontraditional advocacy roles. A similar approach helped give birth to the Montreal Protocol of 1987. Parties to the convention that produced the treaty identified depletion of the UV-absorbing ozone layer by chlorofluorocarbons (CFCs) as a public health threat of potentially catastrophic proportions requiring immediate action, namely, the phasing out of CFCs and related compounds. A role for health care professionals in global environmental policy is a natural extension of a growing ethos of preventive medicine, the sort that has, for instance, reduced the prevalence of smoking in the United States and led to improvements in food, highway, and gun safety. Similarly, it is not too late and none too soon for the health care community to advocate policies that wean us from fossil fuels and ultimately mitigate the extent of human-induced climate change.

Ticks and tickborne bacterial diseases in humans: an emerging infectious threat.

Ticks are currently considered to be second only to mosquitoes as vectors of human infectious diseases in the world. Each tick species has preferred environmental conditions and biotopes that determine the geographic distribution of the ticks and, consequently, the risk areas for tickborne diseases. This is particularly the case when ticks are vectors and reservoirs of the pathogens. Since the identification of Borrelia burgdorferi as the agent of Lyme disease in 1982, 15 ixodid-borne bacterial pathogens have been described throughout the world, including 8 rickettsiae, 3 ehrlichiae, and 4 species of the Borrelia burgdorferi complex. This article reviews and illustrate various aspects of the biology of ticks and the tickborne bacterial diseases (rickettsioses, ehrlichioses, Lyme disease, relapsing fever borrelioses, tularemia, Q fever), particularly those regarded as emerging diseases. Methods are described for the detection and isolation of bacteria from ticks and advice is given on how tick bites may be prevented and how clinicians should deal with patients who have been bitten by ticks.

International Health and Emerging Infectious Diseases

This article explored the role of international health in reducing the impact of infectious diseases by espousing the monumental application of global electronic communication and socioeconomic development initiatives. The interaction between the society and environmental changes have dramatic effects on the frequency of infectious diseases worldwide. Development of dams, human population expansion, migration patterns, urbanization and the invasion of hitherto virgin forests, and global warming enhance the proliferation of vectors of infectious diseases. Sustainable development and emphasis on primary prevention initiatives, coupled with the application of technology to improve farming, provision of safe water and electrification of rural communities, are significant steps in infectious disease control.

Assessment of Arthropod Vectors of Infectious Diseases in Areas of U.S. Troop Deployment in the Persian Gulf

Beginning in August 1990, approximately 800,000 coalition troops were deployed to the Persian Gulf during Operations Desert Shield and Desert Storm. There was substantial concern about arthropod-borne diseases, particularly sand fly fever and cutaneous leishmaniasis, because of high morbidity rates in the Persian Gulf during World War II (WWII). In sharp contrast to WWII, there was no report of sand fly fever among coalition forces and only 31 cases of leishmaniasis among 697,000 U.S. troops. To further evaluate the risk of arthropod-borne diseases, an entomologic survey was conducted in 12 areas of Kuwait and Saudi Arabia. A total of 1,556 arthropods was collected during four survey periods in 1992. The suspected vectors of cutaneous Leishmania major infection, sand fly fever, West Nile fever, Rift Valley fever, and Crimean-Congo hemorrhagic fever were identified; however, there was no evidence of arboviruses or Leishmania among collected specimens nor from 51 trapped rodents. There are several possible reasons for the low risk of arthropod-borne infectious diseases among Desert Shield/Storm troops in an area where suspected vectors frequently were found: the use of insecticides and repellents, and the deployment of most ground troops to the open desert during the cooler, winter period--conditions least favorable for the transmission of arthropod-borne diseases.

Quality of drinking water sources in two sub‐desert sahelian areas in north‐western Senegal

In the course of the agricultural valorization of the Senegal River Valley, the improvement in clean water supply of villages comprised within agriculture zones came as a secondary goal. This study compares water quality between traditional wells and modern sources, such as boreholes and new dug wells, of two village zones located on the left bank of the river. Specific water sources were sampled at three periods of the year, and water quality was assessed. Since water is an important vector of numerous infectious diseases, emphasis was put on the quantitative evaluation of faecal organisms (faecal coliforms and streptococci), indicators of a human and animal contamination of the sources. Physico‐chemical parameters and inorganic compounds complete the general evaluation. Results indicate that the analysed modern water sources are highly contaminated as compared to traditional sources. Modernization of water sources is not a sufficient measure for the improvement in clean water supplies. Users have a stro...

Mite Dermatitis Other Than Scabies

Most mites are small, have mouth parts capable of puncturing, feed on tissue fluids, have a high reproductive rate, and are found in all habitats, including human skin. Mites are important causes of cutaneous diseases and are vectors of important infectious diseases. Mite bites should be considered whenever any unexplained cutaneous eruption is presented to the dermatologist. A knowledge of the biology of the mites that can attack humans is important when taking a history and for identifying the etiology. Treatment of the dermatitis is symptomatic, with a cure depending on the identification and eradication of the causative mite.

A description with scanning electron microscopy on the tick Ixodes persulcatus (Schulze, 1930) male and female specimens.

The surface fine structures of Ixodes persulcatus (Schulze, 1930) male and female specimens were observed by means of a scanning electron microscope. A brief review on the biology of the ticks and their disease relationships was also presented. The sexual dimorphism of the specimen was marked; the male was quite smaller than the female. The genital groove was well developed and deep, the anal groove was distinct and characteristically extending anteriorly around the anus. The 4th article was much reduced and situated on the top of the 3rd article ventrally. The hypostome dentition was usually 3/3. The bottom of the basis capitulum of the male specimen was strictly straight in shape. This species was regarded as one of the most important vectors for infectious diseases of migrating birds.

Injury Control and Product Liability

of these product-related injuries is not obscure, nor are preventive methods lacking, but often they are not implemented. We know, for instance, that tap-water scalds in bathtubs and showers could be eliminated by limiting the maximum temperature achievable by hot-water heaters or requiring the installation of antiscald devices (2). Similarly, air bags in cars would drastically reduce the incidence ofinjury and death resulting from crashes (3), but air bags are still not available in automobiles. A poorly designed product is often the "vector" for injurious forces. In disease epidemiology, efforts are made to control the interaction between vectors (mosquitoes, for example) and man; in product-related injuries, the "vectors" are created and skillfully marketed by man. Unlike most vectors of infectious diseases, product vectors are an integral part of the stream of commerce, affecting the vested financial interests of their manufacturers and retailers. Two basic approaches commonly used with disease vectors are to eliminate the vectors or to prevent their contact with man. With product vectors, elimination of the product or preventing human contact is often impractical, but modification of the product can reduce its potential for transmitting injurious forces to man. Therefore, a vital public health concern is how to provide manufacturers with incentives for designing products that will not injure people. In examining what motivates a manufacturer in the design of a product, it is clear that the marketability of the product and the cost of its production are of primary concern, because these factors will to a large extent

The Breeding Media of some common Flies

When studying the biology of the house-fly or any other fly annoying to man and domestic animals with a view to practical control, it is obvious that a correct knowledge of the breeding-places of the species is perhaps the most important problem which the investigator has to solve. As to the common house-fly (Musca domestica, L.) it is generally held that this problem has been completely cleared up by several workers years ago, but recent observations in Denmark have convinced the writers that this is not the case. We have arrived at conclusions regarding the chief breeding-places of the house-fly differing from those generally found in text-books.Our work has not been limited to Musca domestica, for we have as far as possible studied the breeding-places of other flies occurring in houses or connected with domestic animals, first and foremost the stable-fly (Stomoxys calcitrans, L.). The knowledge of the biology of the stable-fly in Europe is surprisingly meagre, though the practical interest of this species as a tormentor of cattle and horses and a possible vector of infectious diseases is generally recognised.As our observations may be of some interest to workers in other countries we have collected them in this paper, which constitutes the third of a series containing the main results of our investigations into the fly problem started under the auspices of the Health Organisation of the League of Nations and the Danish Committee of Rural Hygiene and with the support of the Danish Ministry of Agriculture and several private funds.