Environmental Health in Emergencies and Disasters
Chapter 10
Leishmaniasis is a vector-borne disease that is transmitted by sandflies and caused by obligate intracellular protozoa of the genus Leishmania. Human infection is caused by about 21 of 30 species th
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at infect mammals. These include the L. donovani complex with 3 species (L. donovani, L. infantum, and L. chagasi); the L. mexicana complex with 3 main species (L. mexicana, L. amazonensis, and L. venezuelensis); L. tropica; L. major; L. aethiopica; and the subgenus Viannia with 4 main species (L. (V.) braziliensis, L. (V.) guyanensis, L. (V.) panamensis, and L. (V.) peruviana). The different species are morphologically indistinguishable, but they can be differentiated by isoenzyme analysis, molecular methods, or monoclonal antibodies.
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Leishmaniasis is a vector-borne tropical/subtropical disease caused by an intracellular parasite transmitted to humans by sand fly bite. It is endemic in Asia, Africa, the Americas, and the Mediterr
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anean region. Worldwide reports include 1.5–2 million new cases each year, more than 300 million at risk of acquiring the disease, and 70,000 deaths per year. Clinical features depend on the Leishmania species and immune response of the host, varying from localized cutaneous disease to visceral form with potentially fatal outcome; however, the common presentation is either cutaneous, mucocutaneous, or visceral leishmaniasis. Many therapeutic agents are being used in Leishmania treatment, but the only effective treatment is achieved with current pentavalent antimonials. WHO considers Leishmaniasis as one of the “Neglected Tropical Diseases” that continues to be prevalent despite international, national, and local efforts towards its control and elimination over the last decade. This chapter reviews the global perspective of Leishmaniasis with increasing recognition of emerging “Atypical forms” and new surge of disease across the world mainly due to increasing conflicts in endemic areas leading to forced migration among other causes. All these challenges related to environment, disease, and vector pose major implications on WHO’s leishmaniasis control and elimination plan.
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This open access book not only describes the challenges of climate disruption, but also presents solutions. The challenges described include air pollution, climate change, extreme weather, and related health impacts that range from heat stress, vector
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-borne diseases, food and water insecurity and chronic diseases to malnutrition and mental well-being.
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WHO is responding as Pakistan is affected by massive monsoon rainfall and unprecedented levels of flooding and landslides. Damage to health infrastructure, shortages of health workers, and limited health supplies are disrupting health services. Significant public health threats include the spread of
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water- and vector-borne diseases, with outbreaks of diarrheal diseases, skin infections, respiratory tract infections, malaria, dengue, injuries, and more. With health services reduced, the management of non-communicable diseases are also affected. In addition, the loss of crops and livestock will have a significant impact on the nutrition and health of many communities who depend on these resources.
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Climate change is a verified, global phenomenon, but its consequences will not be evenly distributed. Developing countries and small island nations will be the most affected. Countries will experience more frequent extreme weather events and resulting changes in water quality and availability, incre
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ased contamination of air, and food security problems. Health impact due to climate change include diarrhoeal diseases, vector-borne diseases, heat stress, malnutrition, deaths and injuries due to extreme weather events and mental stress.
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Int. J. Environ. Res. Public Health 2021, 18(24), 13339; https://doi.org/10.3390/ijerph182413339
The climate crisis threatens to exacerbate numerous climate-sensitive health risks, including heatwave mortality, malnutrition from reduced crop yields, water- and
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vector-borne infectious diseases, and respiratory illness from smog, ozone, allergenic pollen, and wildfires. Recent reports from the Intergovernmental Panel on Climate Change stress the urgent need for action to mitigate climate change, underscoring the need for more scientific assessment of the benefits of climate action for health and wellbeing.
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Leishmaniasis is a climate-sensitive disease. Changes in temperature, rainfall, and humidity can have strong impacts on
the sandfly vector, altering their distribution and influencing their survival and population sizes. Increased temperatures shorten vector development time, reduce Leishmania para
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site incubation time, and increase vector biting rates, allowing transmission
in areas not previously endemic for the disease. Poor and
marginalized communities will be hit disproportionately harder by
the effects of climate change, and droughts, famines, and floods
can also lead to displacement and migration of immunologically
naive people to areas where leishmaniasis is endemic, posing a
threat of leishmaniasis outbreaks.
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Human African trypanosomiasis (HAT) has been an alarming global public health issue. The disease affects mainly poor and marginalized people in low-resource settings and is caused by two subspecies of haemoflagellate parasite, Trypanosoma brucei and transmitted by tsetse flies. Progress made in HAT
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control during the past decade has prompted increasing global dialogue on its elimination and eradication. The disease is targeted by the World Health Organization (WHO) for elimination as a public health problem by 2020 and to terminate its transmission globally by 2030, along-side other Neglected Tropical Diseases (NTD). Several methods have been used to control tsetse flies and the disease transmitted by them. Old and new tools to control the disease are available with constraints.
Currently, there are no vaccines available. Efforts towards intervention to control the disease over the past decade have seen considerable progress and remarkable success with incidence dropping progressively, reversing the upward trend of reported cases. This gives credence in a real progress in its elimination. This study reviews various control measures, progress and a highlight of control issues, vector and parasite barriers that may have been hindering progress towards its elimination.
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The risk of communicable diseases remains a humanitarian concern with major health risks including cholera, acute watery diarrhea, bloody diarrhea, malaria and other vector
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borne diseases and conditions such as severe acute malnutrition.
Access to the affected districts is still conditioned due to the destruction of roads, the telecommunications network and the interruption of electricity.
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Chagas disease, also known as American trypanosomiasis, is a potentially life-threatening illness caused by the protozoan parasite Trypanosoma cruzi. About 6–7 million people worldwide are estimated to be infected with T. cruzi. The disease is found mainly in endemic areas of 21 continental Lati
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n American countries, where it has been mostly transmitted to humans and other mammals by contact with faeces or urine of triatomine bugs (vector-borne), known as kissing bugs, among many other popular names, depending on the geographical area.
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Planning for public health emergencies should ensure that capabilities developed during previous emergencies are maintained, incorporated, and put into practice when a new event of public health concern arises. Investments in pandemic preparedness lead to more rapid detection and a stronger response
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to public health threats, thereby shielding communities from the debilitating social and economic effects of epidemics and pandemics. The Pan American Health Organization (PAHO) recognizes the efforts of countries in the Region of the Americas to develop and/or strengthen their respiratory pathogen pandemic plans. PAHO supports planning activities with tools and expertise, aligning these efforts with the Preparedness and Resilience for Emerging Threats (PRET) initiative. The PRET initiative is an innovative approach to improving disease pandemic preparedness. It recognizes that the same systems, capacities, knowledge, and tools can be leveraged and applied for groups of pathogens based on their mode of transmission (respiratory, vector-borne, foodborne etc.). The PRET initiative incorporates the latest tools and approaches for shared learning and collective action established during the COVID-19 pandemic and other recent public health emergencies.
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Long-lasting insecticidal nets (LNs) constitute a core vector control intervention against malaria. A number of new LN products are under development and will require assessment of risks to humans. This document provides an updated generic model that can be used for the risk assessment of exposure t
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o insecticides of individuals sleeping under LNs and during the washing of nets.
In an Annex, exposures and health risks are described for the conventional treatment or retreatment of nets (ITNs) with an insecticide considering that such practices may still be used in evaluation of ITNs and their use. The generic model does not include the risks associated with the manufacturing of LNs in a factory environment.
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Effective malaria prevention is threatened by widespread and increasing vector insecticide resistance. Failure to mitigate this threat will likely result in an increased burden of disease, with significant cost implications. This new framework provides support for the development of a national insec
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ticide resistance monitoring and management plan as part of a national malaria strategic plan.
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This document provides the specifications for major pesticide application equipment used for control of vectors of diseases. The specification guidelines contained herein are intended to assist national authorities and other public health users in s
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electing equipment of assured quality for application of pesticides for vector control.
The test methods described herein are intended to assess whether the equipment will function for a minimum of three years with appropriate routine maintenance according to the manufacturer’s label instructions. Manufacturers shall be requested to provide warranty against manufacturing defects with guaranteed after-sales service on the equipment, any certification required by national authorities regarding materials used in the construction of the equipment, and results of tests that have been carried out for compliance with national or international specifications.
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Zika virus is primarily transmitted by the Aedes species of mosquito which is also responsible for the spread of dengue, Chikungunya and yellow fever viruses. In most areas, the primary vector of these viruses is Aedes aegypti, with Aedes albopictus a proven or potential vector in some settings. Wel
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l-implemented vector control against Aedes using existing tools effectively reduces the transmission of viruses spread by these vectors. Pilot studies are being undertaken on new tools which have potential for future reductions in Aedes populations
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This document outlines the evaluation process that WHO undertakes to assess novel tools and strategies targeted at VBDs. Its aim is to articulate the linkage between the generation of evidence that demonstrates public health impact of novel interventions, and the development of policy recommendation
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s based on the generated data. The document defines standards for the evaluation process, as well as the steps that an applicant needs to undertake, along with some guiding principles that aim to support applicants in the development of submissions with WHO.
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“Preferred product characteristics” (PPCs) are key tools to incentivize and guide the development of urgently needed health products. Some of the vector control interventions deployed in complex emergencies and in response to natural disasters – namely insecticide-treated nets (ITNs) and indoo
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r residual spraying (IRS) – have already met identified public health needs in more stable settings; other tools such as insecticide-treated tarpaulins have been specifically designed for this use case. Given the diverse mix of existing and potential new interventions and the considerable gaps in the associated evidence base, this PPC aims to clearly articulate the unmet public health needs for tools designed to control malaria transmission in complex emergencies and in response to natural disasters.
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