Further information on guidelines for ethical behaviour can be found on the Health Research Council of New Zealand’s website synthroid 25 mcg low price, http://www buy synthroid 50mcg cheap. This code applies to all personal health information collected as part of outbreak management discount synthroid 125 mcg mastercard. The following rules in the Code have particular relevance for agencies responding to disease outbreaks. The exception is granted “for research purposes (for which approval by an ethics committee, if required, has been given) and will not be in a form which could reasonably be expected to identify the individual concerned”. Data disclosure policies All agencies involved in outbreak investigations should have in place policies for the disclosure of health data and, in particular, data identifying or potentially identifying individuals. These policies need to address what data may be exchanged between organisations taking into account the requirements of the Health Act 1956, the Privacy Act 1993, the Official Information Act 1982, and the Health Information Privacy Code 1994. Cultural competency in outbreak management The urgency of an outbreak investigation and response can encourage a strong focus on the source of the illness and actions to eliminate it. In such situations however it is essential to avoid marginalising the concerns and values of the people primarily affected by the outbreak. The authors of several New Zealand outbreak reports have emphasised the importance of considering the cultural 23 context of outbreaks and the advantages of cultural competency within the outbreak management 24 team. Cultural competency as part of outbreak preparation Build cultural competency within the outbreak management organisation. Cultural competency during the outbreak investigation and response Ensure that the outbreak investigation and response does not disempower communities. Cultural competency while implementing recommendations Develop culturally appropriate recommendations from the outbreak response. The Treaty of Waitangi in outbreak management The Treaty of Waitangi provides a framework for Māori and non-Māori to exercise control over their health and wellbeing, and therefore underpins all health protection work in New Zealand, including outbreak management. Treaty of Waitangi principles derived from the provisions are argued to reflect the spirit and original aims of the Treaty of Waitangi, and to enable contemporary applications. The three principles derived from these sources are partnership, participation and active protection. The provisions are: kawanatanga/ governance – emphasises Māori involvement in all aspects of society within Aotearoa (New Zealand). Outbreak management organisations should encourage meaningful involvement of Māori in outbreak planning, prioritisation, investigation and response tino rangatiratanga/ Māori control and self-determination – refers to on-going relationships between the Crown and Māori with the goal of actively supporting advancement of Māori health aspirations as determined by Māori. This would include the development of Māori capacity for responding to outbreaks directly affecting Māori. Disease outbreak management that improves Māori health outcomes should be prioritised. A framework defining roles and responsibilities in outbreak management in complex situations is described in Appendix 1. Overview of the outbreak management process The overriding goal of outbreak management is to minimise the public health impact of disease outbreaks. Although listed sequentially in the table, these outbreak management components are often not addressed in this order in practice. Control and communication activities are not necessarily preceded by components such as outbreak description and full investigation, and it is often advisable to immediately implement simple practical control measures, where reasonable, following outbreak confirmation. Table 1: Components of outbreak management Components Aims Preparation Optimal level of preparedness Surveillance Consistent and comprehensive collection and review of information on diseases with outbreak potential Confirmation and assessment Sensitive, specific and timely detection of potential outbreaks with public health impact Outbreak description, including Characterisation of outbreak to situational analysis and identify the immediate need for descriptive epidemiology control or hypotheses for further investigation Minimising the public health impact of Full investigation Identification of outbreak source, disease outbreaks transmission mechanisms, Analytic epidemiological contributing factors and control points investigation Environmental investigation Laboratory investigation Outbreak control Prevent further disease transmission Outbreak communication Public and relevant agencies appropriately informed and involved in outbreak management Outbreak documentation Optimal dissemination of recommendations Figure 2, at the end of this chapter, presents a framework showing the interrelationships among these elements. The processes involved in outbreak identification; description and investigation are examples of risk assessment activities, while control, communication and documentation activities represent risk management. The relationship between these two basic groups of activities is fluid, and differs according to the type and setting of each outbreak. The elements of the framework are expanded throughout the remainder of this manual. The following points may be useful in helping understand the framework at this stage: outbreak preparation (Chapter 2) includes the development of an organisational outbreak plan and maintaining general capacity to implement an outbreak investigation and response surveillance (Chapter 3) includes all flows of information that act as raw material to detect outbreaks. These information flows include self-reported outbreaks, notification data and sporadic self-reported illness confirmation and assessment (Chapter 4) includes the processes of verifying that a suspected outbreak is genuine, and assessing the relative needs for investigation and control, as well as overall prioritisation outbreak description (Chapter 5) plays a key role in outbreak investigation. This largely epidemiological function addresses the characterisation of the outbreak, including situational analysis and descriptive epidemiology, identifying its scale, identifying hypotheses and planning further investigation full investigation comprises three major components: analytic epidemiological (Chapters 6, 7 and 8), environmental (Chapter 9) and laboratory (Chapter 10) investigations. These components are not hierarchical in overall importance, nor do they occur in a particular sequence. The relative contribution that each could make to an investigation depends on the type of outbreak, but all should be given consideration outbreak control (Chapter 11) is self-explanatory. Note that outbreak control needs to be considered at all stages of the overall investigation, and may precede or obviate the need for further investigation outbreak communication (Chapter 12) includes communication within the organisation, with the public and media, and with other organisations. Communication is an on-going responsibility outbreak documentation (Chapter 13) refers to the early reporting of detected outbreaks and collation of final information in a permanent form. This information then feeds back into the preparatory stage to continuously improve outbreak management and to prevent further outbreaks. How to use this manual Chapters in the manual have been developed to correspond with the components of outbreak management presented in Table 1. The manual has been developed as a series of independent modules that can be read in the sequence dictated by the circumstances of the outbreak. Preparation Outbreaks seem to invariably arise late on Friday afternoons, during holidays, or when key personnel are already overburdened with other projects. Valuable time is often lost organising the people and materials necessary to investigate and respond to the outbreak while the trail is still warm. Unfortunately, the likelihood of identifying the source of an outbreak and interrupting further disease transmission decreases steadily with every day of delay. Organisations responsible for outbreak management should ensure that they have planned how they will deal with an outbreak when it occurs. An additional part of outbreak planning is to develop and maintain surveillance systems that provide early warnings of an outbreak, and this is discussed in the next chapter. The objective of the plan is to define roles, resources and responsibilities for outbreak management. It is to be noted that while leadership roles for several components may be delegated, it is the Medical Officer of Health that has overall responsibility. Outbreak protocols The outbreak plan should clearly document or identify locally appropriate protocols for outbreak management. Note that these protocols differ from outbreak investigation protocols, which describe standardised processes to follow when collecting and recording information. By contrast, outbreak protocols should encompass the entire outbreak management process. Outbreak protocols should suggest thresholds for each stage of the outbreak investigation and response, including whether investigation should commence at all. This manual suggests an approach to outbreak investigation and response, and this may be appropriate for use as a template for developing district protocols.
Section 2 Procurement and management of supplies and equipment 49 Sterilisation Pressure control valve Sterilise syringes and needles using a (air removal/steam release/pressure valve) pressure cooker type steriliser buy 50mcg synthroid. Gasket Base (chamber cheap synthroid 200 mcg fast delivery, vessel) Parts of a pressure cooker type steam steriliser Loading the syringe and needle rack Loading a tray and needle cases 50 Section 2 Procurement and management of supplies and equipment Table 2 50mcg synthroid visa. To make assembly after pack the trays or container or the needle case too sterilisation easier, place syringes near the tightly. Position the V support, trivet or shelf using a hard water pad, place this in the water. If using a steriliser drum, make sure valve is down and the pressure control (pc) valve the vents (holes) are open and position the is opened. After a few minutes of heating, water will start boiling and steam will start escaping strongly from • Before sterilising, check the small pin in the safety the pc valve. During valve is down and the pressure control (pc) valve this period, air will be flushed from the steriliser is opened by pushing up the lever. The steam can be heard escaping minutes of heating, the water will boil and steam and forms a strong and steady jet. Start timing for 15 minutes, turn the heat flushed from the steriliser with steam. The steam down making sure steam can still be clearly heard can be heard escaping and forms a strong and escaping from the pc valve at all times. When the timer rings, close the pc there should be 20 minutes of uninterrupted valve by pushing down the lever. In total there should be 20 and open the pressure valve to release the steam minutes of uninterrupted steam. Leave the steriliser allow the pressure to reduce (if the steam is not and its contents to cool for at least 1 hour. After all the steam has escaped, close • Before using the sterilised supplies, check the the pc valve so that sterility is maintained. Assembling directly from the steriliser and steriliser drum • Do not open the sterilised unit until you are ready to use the sterilised syringe and needle. Place the forceps so that the tips lay Sterile forceps resting on the steriliser lid inside and the handle rests on the edge of the lid. Fitting the plunger into the barrel using sterile forceps Fixing the needle into the syringe using sterile forceps • Use the forceps to pick up the needle by its hub and to fit the needle on the syringe. Turn the needle to fix it securely • Be careful not to touch the needle shaft or bevel. Or remove using sterile forceps to lift out the barrels and plungers and to place them in a sterilised container. If you are not using needle cases, Storing sterilised syringes take out the needles using sterile and needles forceps and place in a sterile container. Assembling from stored sterile containers • Do not open the sterilised unit until you are ready to use the sterilised syringe and needle. Hold the barrel in your hand being careful to touch only the outside, not the hub. Section 2 Procurement and management of supplies and equipment 53 Practical tips for sterilising syringes and needles ● Never use soap, detergents or chemical disinfectants for soaking or cleaning sterilisable syringes and needles. Traces of these chemicals left on syringes and needles can cause irritation and inactivate vaccines. However, hard water salt deposits reduce the life of reusable syringes, and in hard water areas they will only last for about 140 sterilisation cycles. Using hard water pads during sterilisation can help to extend the life of reusable syringes. The high temperatures required for effective sterilisation damage disposable syringes and needles. Practical tips on using and re-using gloves Health workers should: ● Wear gloves to protect against infection during certain patient procedures, e. If there are not enough disposable gloves for a ‘one use’ only approach, wash and disinfect gloves carefully between use: ● Examine gloves carefully and dispose safely of damaged gloves, e. To check for tears or punctures: – Gently blow into the gloves until they are full of air, twist the cuff and hold them under clear water. Good quality latex gloves can be disinfected using either of these methods five or more times. Sprinkle gloves inside with talcum or starch powder when dry and before re-use, to re-lubricate them. Proper management of waste products helps to keep the health facility clean and tidy, prevents the spread of disease, reduces the risk of injury, and prevents re-sale and re-use. Incorrect management of waste places waste handlers, health workers and the community at risk of infection and injury. Waste handling and management Waste handling, treatment and disposal methods must be practical, safe, affordable, appropriate and sustainable. To ensure proper management of waste: • Adopt a safe disposal policy that conforms to national guidelines. This includes appointing an official waste handler to collect and manage waste, and making sure health staff sort the waste they produce into categories for different disposal methods. Provide waste handlers with protective clothing (overalls), heavy duty gloves and boots; provide clinic staff with disposable gloves, and provide goggles to those responsible for incineration to protect their eyes. Waste collection, treatment and disposal Waste material should be sorted, ideally at the site where it is generated, for collection. In some urban areas, the MoH may collect waste for centralised treatment and disposal. If there is no collection service, seperate waste into material for incineration, burning or burying and, where appropriate, recycling or re-use. Collect waste daily and take it to a secure, safe central collection or storage point for treatment and/or disposal. Follow these practical guidelines: • Collect waste in good quality metal or plastic buckets which have a close-fitting lid or in strong, leakproof plastic bags. If you use chlorine for disinfection, use plastic buckets because chlorine causes metal buckets to rust. In very hot climates, organic waste such as organs and placenta should be disposed of immediately if possible. The site should be at least 30m away from the health facility and from drinking water sources, to avoid contamination. Section 2 Procurement and management of supplies and equipment 55 • Put up a fence around pits or incineration sites. This should secure and protect against theft and scavenging and prevent accidents and entry of animals and unauthorised persons. Collection and disposal of sharps waste Sharps are items that can pierce the skin, for example needles, lancets and scalpels. Proper disposal of sharps, in particular needles and syringes, is therefore extremely important and methods for collecting sharps waste are described below. These methods also reduce the risk of infection from re-use of disposable needles and syringes by encouraging disposal at point of use.
The with the distance from the nearest coca fails to bring out clear overarching patterns order 200mcg synthroid visa. Once socioeconomic After several potential covariates other than coca bush cultivation in two ways — the variables were included synthroid 125mcg on line, the study did not coca bush cultivation were included in the distance to the nearest coca bush cultiva- support the thesis that coca is very different model purchase synthroid 125 mcg line, such as urban population density, tion site and the area under such cultivation from other crops; instead it hypothesized road density, the initial forested fraction, in the surrounding square kilometre — and that what sets municipalities growing coca the fraction of the population with unsatis- examined how the probability of defor- bush apart is poor rural development, the fed basic needs and eradication by aerial estation varied as a function of these two underlying cause that enables a positive spraying, the best-ft model indicated that variables. Other variables usually associated association between population growth coca bush cultivation was not a signifcant with the probability of deforestation were and deforestation. However, the phenomenon may extend beyond this, as it can trigger violent land grabs, China ± generate conflict over land tenure, attract not only licit but also other illicit activity and, as mentioned earlier, Myanmar generate a need to launder illicit proceeds, a need that can Viet Nam be addressed by converting forest for activities such as cattle ranching. Local smallholders may others, “High-resolution global maps of 21st-century forest cover change”, Science, vol. This suggests that other factors, possibly socioeco- 109 Kendra McSweeney and others, “Drug policy as conservation nomic factors not included in the model, are the main policy: narco-deforestation”, Science, vol. Shriar, “Theory and context in analyzing livelihoods, land use, and land cover: lessons from Petén, Guatemala”, Geoforum, vol. Centro Internacional de Investigaciones Forestales, Facultad Latino- americana de Ciencias Sociales, 2009). Shriar, “Theory and context in analyzing livelihoods, land areas of Petén, Guatemala”, Conservation and Society, vol. These chemicals include solvents; Honduras, 2004-2012 metals and salts; and acids and bases. Exposure to such chemicals can result in numerous health complications, 250 ranging from eye, nose and throat irritation to liver and kidney impairments and bleeding and corrosion in the 200 lungs. Forest loss (calibrated, km²) The consequences in urban settings not only pose health Source: K. According to the European Police Office (Europol), criminals engaged in the illicit manu- facture of drugs may resort to simply dumping chemicals, A quantitative link between drug trafficking and deforesta- burying them in the ground, leaving them in stolen trailers tion has been made in the case of Honduras. Forest loss and draining liquids into sewerage systems, into or onto in eastern Honduras over the period 2004-2012 appears the ground or into surface water. Other techniques involve to correlate with the number of registered air and maritime burning waste in stolen motor vehicles or mixing the landings of cocaine shipments from South America to chemicals with other chemical waste prior to releasing Honduras, as recorded in the Consolidated Counterdrug them into the open sea from maritime vessels. Three interrelated mechanisms may explain The chemicals used in the illicit supply chain of cocaine this relationship: direct deforestation from landing strips and opiates also contribute to pollution and health hazards and illegal roads; indirect deforestation from land grabs in rural environments. A comparison of the use levels of chemicals and waste the most commonly used legal agrochemicals with the manufacturers’ recommendations indicated that, overall, Target 6. There is potential for pollution by the use of land and soil, including land affected by desertifica- First time in treatmentFirst time in treatment tion, drought and floods, and strive to achieve a the above-mentioned substances by the great number of land degradation-neutral world laboratories, which are scattered throughout the Amazo- nian forest; however, the combination of high rainfall and In Afghanistan, opium poppy cultivation places an addi- reuse probably reduces the environmental impact of these tional strain on the availability of water in areas already sources. Indeed, in the early 1990s, field observations in affected by water scarcity, and the irrigation methods used Chapare, Bolivia, found that rainfall quickly diluted chem- 122 also contribute to salinization of desert areas. According to one report,123 in the Province of Helmand, which continues to be affected by high levels of opium poppy cultivation (covering 27 per cent of arable land in 122 Ray Henkel, “Coca (Erythroxylum coca) cultivation, cocaine pro- duction, and biodiversity in the Chapare region of Bolivia”, in Bio- diversity and Conservation of Neotropical Montane Forests, Steven P. Rather than being evenly irrigation resulted in a reduction of 98 per cent of the distributed throughout the world, biodiversity is concen- water flow along the lower Helmand river and the com- trated in lowland moist tropical forests,130, 131 while mon- plete loss of the formerly rich downstream wetlands. In tane tropical and subtropical forests are recognized as addition, drought appears to have intensified over time. Opium poppy cultiva- that range in 12 seasons and above that range in just 2 tion in the Andes is of particular concern, as the altitude seasons. At the same time, population growth has not suitable for such cultivation also corresponds to the espe- abated, leading to intensification of cropping at the cially vulnerable Paramo and sub-Paramo ecosystems. The highlands of the Lao People’s Democratic Republic and Myanmar as they did in Chahar Bolaq, to the extent that no water 127 are part of the Indo-Burma biodiversity hotspot, which is was available downstream. In contrast, the growers estimated to harbour in excess of 13,500 plant species, dependent on tube-well irrigation north of the Boghra 7,000 of which are found nowhere else, but has less than canal are among the least powerful and most marginal 5 per cent of natural land cover remaining. Satellite-based data reveal clusters of persistent ing (or renting) and fuelling pumps, lowering the water coca bush cultivation in protected areas (national parks) table and ultimately degrading the marginal lands. In Colombia, the protected already low capacity of the soil, leading to decreasing areas most affected are encircled by a moving front of opium yields (such as the exceptionally low yield in the agriculture including coca bush cultivation in Sierra de La south in 2015), while the process of degradation may have Macarena, Tinigua and Los Picachos national parks (see been exacerbated by poor water management. Biodiversity and protected areas In Peru, the extent of coca bush cultivation in protected areas is limited. Joppa, “Global patterns of terrestrial vertebrate diversity and conservation”, Proceed- ings of the National Academy of Sciences, vol. Olson and others, “Terrestrial ecoregions of the world: a (Kabul, Afghanistan Research and Evaluation Unit, 2006). Pimm, “Elevational ranges 2010-11 growing season”, Case Study Series (Kabul, Afghanistan of montane birds and deforestation in the western Andes of Colom- Research and Evaluation Unit, 2011). Amazonia Andean ción-Lares revealed that 2 per cent of the land area wasChococommunal participation and the promotion of landOrinoco occupied by coca cultivation, most of which (90 per cent) ownership, community organization, good agricultural was on land without agricultural potential. Slightly less practices, including in post-harvest processes, agroforestry than a quarter of the coca cultivation was in protected and forest management. One successful instance of alternative development extend- In the Plurinational State of Bolivia, the most affected ing to positive environmental effects can be seen in the parks are Isiboro Secure and Carrasco. The first overlaps San Martín Region in Peru, where alternative development with the Alto Beni deforestation front and the second initiatives included the replacement of coca production overlaps with the Chapare-Santa Cruz deforestation front. An additional 687 Impact of drug control interventions on families were involved in 1,415 ha of agroforestry and the environment coffee and cocoa cultivation for fair trade and organic markets. The success of the project rested on the provision Alternative development of non-conditional support to beneficiaries, whether or Target 2. The premise of this strategy is that land owner- which efforts to reduce illicit drug supply contend with ship discourages smallholders from joining or rejoining the socioeconomic conditions of farmers, as well as the the coca economy and allows for the development of long- environment in which the farmers live and earn their term productive projects. Although short-sighted initiatives in the past were not assessed in the project, land ownership also has the potential to slow down the agricultural frontier. In South-East Asia, for example, crop substi- geted for spraying and taking coca bush cultivation to new tution has been criticized for promoting the shifting away municipalities nearby. This explains the shifting of the from swidden agriculture, which allows for fallow periods Andean and Chocoan forest frontiers by coca bush during which the land may regenerate, towards permanent growers. Analyses of does not necessarily translate into unsustainable deforesta- satellite imagery of eastern Bolivia146 implied that that tion. Aggressive campaigns to counter drug traf- agriculture between the 1970s and 1990s took place in ficking and to eradicate coca bush in the 1990s were iden- parallel with a decline in the overall use of land and the tified as the main causes of the decline in forest clearing regrowth of forest on the steepest slopes, even as the popu- from the late 1980s to the 1990s. This highlights the The impact of illicit crop eradication on the environment difficulties in separating deforestation associated with or may have different outcomes and different ramifications caused by coca bush cultivation from land-use change depending on the context. If eradication induces a dis- caused by other activities along the forest frontier. In Afghanistan, for example, the targeted “food zone” that coca production had taken place in 8 of the top 10 initiative in central Helmand, including eradication, may municipalities gaining forest vegetation in 2001 and the have played a role in the relocation of opium poppy grow- total amount of coca produced had dropped markedly by ers north of the Boghra canal and the associated expansion 2010 (to 30 per cent of the initial amount), probably as a of the agricultural frontier north of the canal, which almost result of eradication efforts. In Colombia, since 1994, most coca In the Andean countries, the easiest way for farmers to bush eradication has been conducted by aerial spraying evade law enforcement is to establish their coca bush cul- with the herbicide glyphosate. One study provided 145 Alexander Rincón-Ruiz, Unai Pascual and Suzette Flantua, “Exam- ining spatially varying relationships between coca crops and associ- quantitative evidence to substantiate an overall shift in ated factors in Colombia, using geographically weight regression”, coca bush cultivation towards municipalities with a higher Applied Geography, vol. Killeen and others, “Total historical land-use change in eastern Bolivia: who, where, when, and how much?
Use of the sterile insect technique to control and eradicate the fly has been tested in large-scale breeding stud- ies buy synthroid 75mcg with mastercard, but this approach has a disadvantage in the case of Dermatobia because effective 25mcg synthroid, unlike C 75 mcg synthroid visa. They finally appear as third- stage larvae under the skin, where they form subcutaneous furunculoid nodules. Approximately one month after the initial infestation, these nodules rupture, and the larvae fall to the ground and begin to pupate. In cats, the larvae may be found in subcutaneous pruriginous lesions, frequently in the nape of the neck or the sub- mandibular region. In addition, there have been serious or fatal cases in which the par- asite was found in the eyeball or surrounding tissue, trachea, or central nervous sys- tem of cats (Glass et al. Most of these cases involved second- or third-stage larvae that had formed furuncular lesions in the neck, chest, or back, and they occurred at the end of summer or in early autumn. It is unusual to recover first-stage larvae; when this happens, the parasite is found in the vitreous humor or the upper respiratory tract, and the lesions appear at the end of spring or in early summer. The times of the year when the first-, second-, and third-stage larvae of Cuterebra appear would suggest that the parasite migrates through the lungs and the head before maturing in subcutaneous tissue. This myiasis is caused by the larvae of two fly species, Hypoderma lineatum and H. Parasitized cattle have occasionally been introduced in Australia, South Africa, and several South American countries, but the species did not become permanently established. In cattle, they lay their eggs on hairs on the lower part of the body, preferentially the feet. The larvae are born after two to six days and invade the subcuta- neous connective tissue, from which they migrate to the rest of the body. In both cases, the larvae remain for a while in their respective sites, and then in winter (January and February), they finally migrate to the subcutaneous tissue of the dor- solumbar region, where they arrive as second-stage larvae and mature into third- stage larvae within 10 to 11 weeks. During this time, they form cysts about 3 cm in diameter, with a pore through which to breathe. The larvae spend about 10 months of their 11- to 12-month development cycle inside the animal’s body. In their final stage, the larvae emerge through the hole in the cyst, fall to the ground, and pupate. An abundance of adult flies causes restlessness in cattle and can provoke stampedes and interfere with their feeding. These losses are due to delayed growth, lowered milk and meat production, and damage to the hides. Development of the par- asite in humans is usually arrested in the first larval stage and rarely reaches the third, or mature, stage. A serologic study of more than 100 cases in France led to the conclu- sion that the species that most frequently affects man is H. The myiasis it causes is subcutaneous and only occasionally conjunctival or palpebral-conjunctival. The cutaneous forms can be mani- fested as a serpiginous myiasis, similar to cutaneous larva migrans, or as a subcuta- neous myiasis with moving furuncles that appear and disappear. Authors have described several cases of eosinophilic syndrome with fever and muscle pain, as well as respira- tory, muscular, cardiac, dermal, or neurologic symptoms, in patients who turned out to have myiasis caused by H. In several of these cases, the diagnosis was made when furuncular lesions appeared, usually in the scalp, and the symptoms disappeared spontaneously after they were excised (Navajar et al. It is possible that the human parasitosis is more common than has been believed in the past, but that it goes unnoticed. The use of insecticides or repellents in animals at risk can be successful if they are applied at the appropriate time of year, since the season for adult infestation is relatively brief. Most of the development of Hypoderma takes place inside the animal (10 months to a year), and hence the larval phase is a good point at which to attack the fly. Control consists of treating cattle with larvicides at the beginning of autumn to prevent the lar- vae from completing their development cycle and becoming established under the skin. Treatment at this point interrupts the life cycle of the fly and at the same time avoids damage to the hide. To prevent neurological damage to the animals, the larvicide should not be applied in late autumn, when H. In animals being raised for food, the application of insecticides should take into account the time lapse required between administration of the insecticide and use of the meat or milk. Also, delayed treatment can be given in the spring when the subcutaneous larvae are first noticed; in this case, topical insecticides are used, reaching the larvae through the furuncular orifices. Promising results have also been obtained in Ireland, where the infestation rate has been reduced to very low levels. Myiasis Caused by Larvae of Oestrus ovis and Rhinoestrus purpureus The adult fly of Oestrus ovis is gray and measures 10–12 mm in length. It is larviparous and deposits its larvae in the nostrils of sheep, goats, and, occasionally, man. The larval forms are obligate parasites of equines—in whose nostrils and lar- ynx they develop—found in Africa, Asia, and Europe. The first-stage larvae enter the nasal fossae, where they feed on mucus and desquamated cells, and they then move on to the frontal or maxillary sinuses, where they mature. After 2 to 10 months, the mature larvae return to the nasal fossae, where they are expelled by sneezing, fall to the ground, and pupate for four to five weeks. The adult flies are annoying to the animals, and when they are very abundant, they cause the animals to become restless. The pathology of this condition has been attributed to the mechanical effect of the size of the larvae and the irritation caused by their spines on the mucosae of the nose, pharynx, and sinuses. Some findings indicate that hypersensitivity, probably IgE-mediated, plays an important role. The examination of human cases, however, has not demonstrated the presence of hypersensitivity in man (Dorchies, 1997). The parasitosis occurs most often in sheep herders and is also seen in urban dwellers who keep sheep in residential areas (Dar et al. The form for which people most often seek treatment is invasion of the conjunctiva, evidenced by lacrimation and the sensation of a foreign body in the eye. Of 112 sheep herders interviewed in Italy, 80% stated that they had had the infestation at some time, and 54% reported that more than one site had been infected at the same time. The sites where larvae were found most fre- quently were the larynx (77 times), the conjunctiva (56 times), and the nasal fossae (32 times). The most common sign was pain, sometimes accompanied by fever and general malaise (Pampiglione et al. In Benghazi, Libya, 80 cases of external ocular myiasis were diagnosed over a two-year period, representing an estimated incidence of 10 per 100,000 population (Dar et al. In a case in Thailand, eight larvae were recovered from the palpe- bral conjunctiva (Nacapunchai et al. Human oestriasis is usually a benign condition that lasts only a few days because the larvae cannot develop beyond the first stage in man. Serious cases, with destruction of the eye and perforation of the orbital walls, are rare. Treatment with modern systemic insecticides is effective against all the larval phases, and, if it is applied annually, it can greatly reduce the populations of these flies at livestock-raising establishments.
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