48 



MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE 



the Intermountain States, the Lower Rio Grande 

 Valley, and the Central Valley of California. In 

 addition to their avid and pestiferous hunger for 

 human and animal blood, a few species of mosqui- 

 toes transmit human and avian malaria, fowl pox, 

 infectious anemia, as well as encephalitis. 



In an irrigated region, the storage reservoirs, 

 water conveyance systems, farm distribution sys- 

 tems, and drainage systems provide favorable con- 

 ditions for the production of mosquitoes, horse 

 flies, and deer flies. Similarly favorable conditions 

 are often found in coastal areas and near lakes. 

 These insect pests give the word "pests" a really 

 distressful meaning even without transmittal of a 

 primary infectious agent. Some individuals, espe- 

 cially children, often require medical attention for 

 treatment of secondary infection and serious aller- 

 gic reactions to mosquito bites. These problems, 

 present in all irrigated areas and in many areas 

 without irrigation, have resulted in the formation 

 of organized mosquito control districts and the ex- 

 penditure of large sums of money. For example, in 

 California mosquito control districts operate in 

 over 40 counties. About 75 such districts now oper- 

 ate in the Western States alone, involving the esti- 

 mated expenditure of about $9 million annually. 



Histoplasmosis is a lung disease of humans. It 

 is caused by a fungus that thrives on collected 

 poultry and other bird droppings. Dusts emanat- 

 ing from such droppings carry the fungus through 

 the atmosphere. Incidence of human infections are 

 relatively high in the Middle West and the Middle 

 Atlantic States (100). 



The potential for disastrous outbreaks of com- 

 municable diseases from livestock is recognized 

 and a high level of vigilance in disease control is 

 maintained and consistently improved. 



Plant Disease Organisms 



The serious impact on agriculture and forestry 

 of such infectious agents as plant disease orga- 

 nisms and their vectors is briefly discussed in ap- 

 pendix I. These organisms have no restrictions in 

 moving from field and forest to the flora of parks, 

 streets, highways, and suburban lawns and gar- 

 dens, and vice versa. About one-fourth of the 

 dollar sales of pesticides in the United States 

 comes from small packages sold for use by com- 

 munity and suburban dwellers. Certainly one can- 

 not say that plant and tree diseases in nonrural 

 America arise from agricultural crops and forest 



trees, but coping with these infectious agents must 

 involve all facets of the environment. 



Allergens and Poisonous Weeds 



Ragweed, goldenrod, bermudagrass, walnut 

 trees, and a host of other weeds, economic plants, 

 and trees produce pollens and toxins that cause 

 serious human allergies even in most of our heavily 

 populated areas. Allergies reduce working effi- 

 ciency, impair health, and increase medical costs 

 of our people. 



Allergies from pollen are indeed costly. The 

 Public Health Service reports that in the average 

 year, there are 12,646,000 sufferers from asthma or 

 hay fever, or both. Of these, about 5 million are 

 asthma sufferers, with about 75 percent of the 

 asthma cases caused by pollen. The remaining 7,- 

 646,000 suffer from pollen allergies. About 10,433,- 

 000 workdays are lost each year with a loss in 

 wages — assuming an average daily wage of $12 — 

 of at least $125 million. Loss of production capac- 

 ity by industry would add to this figure. 



Little pollen grains can run up big figures in 

 human misery. 



Poison ivy, poison oak, and other poisonous 

 weeds cause nearly 2 million cases of skin poison- 

 ing each year. The resulting 330,000 lost workdays 

 represent a more than $4 million cost in wages 

 alone. The loss due to restricted activity would in- 

 crease this amount. 



Fungus spores produced on stored pulpwood 

 cause sarcoidosis in man. Such spores from stored 

 maple logs cause human allergies. These fungus 

 spores are also spread to healthy trees. 



Allergies caused by pollen and toxins affect the 

 use of parks and recreation areas. Health problems 

 caused by allergens are becoming more widespread 

 as more people use naturalized parks, campsites, 

 and other rural recreation areas. 



Insect Vectors 



During man's long struggles with a hostile 

 Nature, the host of human diseases carried by in- 

 sects and other arthropods has been a veritable 

 scourge to man's survival. Livestock, birds, wild 

 animals, and vermin may also be sources. 



Simmons (105) lists a number of diseases, in- 

 cluding some of the most important diseases in the 

 world, that can be completely or partially con- 

 trolled by exterminating the appropriate arthro- 

 pod vector by a powerful insecticide : 



