Emerging Vectorborne Diseases and Their Control

摘要

Principally a combination of human population growth, environmental degradation, public health inadequacies and rapid global transportation has put the world at mounting risk from vectorborne and other infectious diseases. Health problems associated with the emergence of new pathogens and the re-emergence and spread of old ones have gained a new urgency due to the global threat of bioterrorism. A large percentage of emerging diseases are vectorborne and over one-third of the agents on the list of greatest concern from bioterrorists are vectorborne. Many of these diseases are caused by viruses for which there are no effective drugs for treatment or vaccines for prevention. Drug and insecticide resistance has further complicated our ability to respond effectively to these growing threats. Parasitic diseases like malaria, leishmmaniasis and African trypanosomiasis are resurging in many regions. Onchocerciasis and to a lesser extent filariasis control programs are reducing the impact of these diseases. This has largely been possible because of a long-lasting new filaricide (Ivermectin) and targeted application of insecticides to highly specialized development sites (i.e., riverine rapids). Chagas disease also has declined significantly in the southern part of its range through home improvement and indoor application of insecticides against domicilary kissing bug vectors. Current outbreak of West Nile virus in North America and dengue worldwide are examples of emerging threat from mosquito-borne arboviruses, even in developed countries. Lyme disease, the most prevalent vectorborne disease in the U.S. with nearly 18,000 cases annually, was not recognized until the early 1980's and was followed by the emergence of another tick-borne disease, ehrlichiosis, in the 1990's. The ongoing West Nile epidemic highlights the fact that while mosquito control remains the first line of defense, the main adulticides and application strategies available for combating epidemics of mosquito-borne diseases today are the same as those used > 25 years ago. Adulticides alone have not adequately protected populations from further transmission and disease spread. The demise of vector control programs and their qualified staffs during the 1980's caught many states unprepared. The U.S. is experiencing a vector control crisis at a time when disease threats and control needs are increasing. The recent Institute of Medicine report: "Microbial Threats to Health," offers remedies for reversing this imbalance. It recommends investment to increase the armamentarium for vector control. Even without new tools, many lives could be saved with current technology if political will and adequate resources were committed to reducing the burden of these diseases.