WHY PERSONAL PROTECTION IS SO IMPORTANT?
Personal protection is very important because of the deadly nature of the diseases that biting-insects carry. Personal protection in the form of repellents and insecticide-treated BEDNETS reduce the incidence of vector-borne diseases by preventing human/vector contact. MALARIA is one of the planet’s deadliest diseases. It is the major public health problem facing mankind, representing a permanent threat for almost half of the world¹s population.
According to the World Health Organization there are 300 to 500 million clinical cases of MALARIA each year resulting in 1.5 to 2.7 million deaths. In 1992, some 90 countries or territories were considered malarious. For comparison, in 1995, there were 140 countries or areas where MALARIA was endemic.
Children under the age of five are the most vulnerable: MALARIA is responsible for the death of at least one million children annually, half of African children under the age of five. However, MALARIA is just one of many vector-borne diseases.
Of special significance due to the deadly nature of the disease is DENGUE fever, particularly its more virulent form, DENGUE haemorrhagic fever. Over 60% of the world population is exposed to endemic or epidemic DHF. Each year there are estimated to be tens of millions of cases of DENGUE fever and hundreds of thousands of cases of DHF, a leading cause of hospitalization and deaths among children in many countries. The permanent migration of people between countries, facilitated by modern transportation, puts in a state of alert those countries whose inhabitants live in regions of less than 1,800 meters above sea level.
Aedes aegypti, the mosquito which vectors the disease, bites during day time, therefore, personal protection becomes essential. Drug-resistant pathogens and pesticide-resistant vectors mean that there are fewer tools to control MALARIA and other vector-borne diseases. Increasing drug-resistance makes treatment for MALARIA more costly and less practical. There is no specific treatment for many vector-borne diseases. This includes DENGUE fever. There are no commercial vaccines for most vector-borne diseases, including MALARIA and DENGUE fever. There is increasing evidence that aerial insecticides do not significantly reduce the adult mosquito population. There are serious environmental and ecological problems associated with the use of aerial insecticides. Vector-borne diseases impose a cost on individuals, communities and countries in terms of their health and socio-economic development which is impossible to quantify.
TRENDS THAT WILL ENSURE THE SPREAD OF VECTOR-BORNE DISEASES AND GROWTH OF THE INSECT REPELLENT MARKET
- Unchecked urbanisation and population growth coupled with substandard housing and inadequate water, sewer and waste management systems.
- The increased use of dams for irrigation and energy generation creating new breeding grounds for mosquitoes.
- Increased aeroplane travel and freight movement transporting pathogens and vectors.
- The increased movement of immigrants and refugees from endemic areas to non-endemic areas.
MALARIA AND DENGUE FEVER IN NORTH AMERICA
MALARIA and DENGUE fever are not currently established in the US although they are introduced regularly and have been established there previously. Travellers returning from endemic regions frequently introduce these diseases into areas with competent vectors. Between 1 977 and 1 994, 2,248 suspected cases of imported DENGUE fever were reported in the US. Legal immigrants, refugees and illegal immigrants and migrant workers are two possible sources of introduction of these diseases into the US in amounts sufficient to promote their establishment. DENGUE fever and MALARIA are endemic in areas that are important sources of immigration to the US such as South East Asia, Mexico, Puerto Rico, and Central/South America. Competent vectors of MALARIA and DENGUE fever are established in the US. Even though MALARIA was eradicated from the US previously, if it were to re-establish itself, resistance of the vector to pesticides would make present-day control more difficult. According to Health Canada there were 483 reported cases of MALARIA in Canada in 1 993, and approximately 431 in 1994. The Centers for Disease Control and Prevention in the United States received reports of 910 cases of MALARIA in 1 992 and seven of those cases were acquired there. In 1 970, reported MALARIA cases in the U.S. were 4,247 with more than 4,000 of the total being U.S. military personnel.
IMPORTANT VECTOR-BORNE DISEASES IN NORTH AMERICA
Arboviral encephalitis. At least 18 arbo-viruses cause encephalitis. Seven are present in the US: Eastern equine encephalitis; Western equine encephalitis; St Luis encephalitis; California encephalitis; La Crosse encephalitis; Venezuelan equine encephalitis and Powassan encephalitis. Most cases of arboviral encephalitis occur between June and September. However, in milder parts of the country cases can occur into the winter months.
Lyme disease has become the most prevalent arthropod-borne illness in North America. In 1 997 more than 12,500 cases were reported to CDC by 48 states. There have been over 103,000 cases reported since 1 982. CDC reports a 25-fold annual increase in reported cases since 1 982. Lyme disease has also been reported in Germany, Switzerland, France and Austria. Rocky Mountain Spotted Fever, is a potentially life threatening infection now recognized as an important cause of illness throughout the USA; some 700 cases are reported annually.
This list demonstrates that even in North America, where there is currently only a small risk of infection from tropical diseases, biting-insects present a significant threat to public health. It is our belief that in the near future climatic changes, migration and international travel and trade, will ensure that the use of insect repellents in temperate climates, such as North America, will become more closely associated with disease prevention, as it is in the Tropics, rather than just with the enjoyment of outdoor activities.
GLOSSARY | DICTIONARY
*Sources : The MALARIA Control Programme, World Health Organization, Third World Network Features, Health Canada, The Centers for Disease Control and Prevention, Health Communications and Public Relations, WHO, Geneva. Manson’s Tropical Diseases, XXth. Edition.