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Monday, 14 March 2011 17:25

Biological Hazards among Forestry Workers

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People active outdoors, especially in agriculture and forestry, are exposed to health hazards from animals, plants, bacteria, viruses and so on to a greater degree than is the rest of the population.

Plants and Wood

Most common are allergic reactions to plants and wood products (wood, bark components, sawdust), especially pollen. Injuries can result from processing (e.g., from thorns, spines, bark) and from secondary infections, which cannot always be excluded and can lead to further complications. Appropriate protective clothing is therefore especially important.

A comprehensive description of the toxicity of plants and wood products and their components is not possible. Knowledge of a particular area can be acquired only through practical experience—not only from books. Possible safety measures must derive from knowledge of the specific area.

Large Mammals

Using horses, oxen, buffalo, elephants and so on as work animals can result in unforeseen dangerous situations, which may lead to injuries with serious consequences. Diseases transmittable from these animals to humans also pose an important danger.

Infections and Diseases Transmitted by Animals

These constitute the most significant biological hazard. Their nature and incidence varies strongly from region to region. A complete overview is therefore not possible. Table 1 contains a selection of infections common in forestry.

Table 1.  Selection of infections common in forestry.

 

Cause

    Transmission         

Locations

Effects

Prevention/therapy   

Amoebiasis

Entamoeba histolytica

Person-to-person, ingestion with food (water, fruits, vegetables); often asymptomatic carriers

Tropics and temperate zone

Frequent complications of the digestive tract

Personal hygiene; chemoprophylaxis and immunization not possible.

Therapy: chemotherapy

Dengue fever

Arboviruses

Aedes mosquito bite

Tropics, subtropics, Caribbean

Sickness results in immunity for one year or longer, not lethal

Control and elimination of carrier mosquitoes, mosquito nets.

Therapy: symptomatic

Early summer meningo-encephalitis

Flavivirus

Linked to the presence of the ixodes ricinus tick, vector-free transmission known in individual cases (e.g., milk)

Natural reservoirs confined to certain regions, endemic areas mostly known

Complications with later damages possible

Active and passive immunization possible.

Therapy: symptomatic

Erysipeloid

Erysipelotrix rhusiopathiae

Deep wounds among persons who handle fish or animal tissue

Ubiquitous, especially infects swine

Generally spontaneous cure after 2-3 weeks, bacteremia possible (septic arthritis, affected cardiac valve)

Protective clothing

Therapy: antibiotics

Filariasis

Wuchereria bancrofti, Brugia malayi

From animal to humans, but also from some types of mosquitoes

Tropics and subtropics

Highly varied

Personal hygiene, mosquito control.

Therapy: medication possible

Fox tapeworm

Echinococcus multilocularis

Wild animals, esp. foxes, less commonly also house pets (cats, dogs)

Knowledge of endemic areas necessary

Mostly affects liver

No consumption of raw wild fruits; dampen fur when handling dead foxes; gloves, mouth protection

Therapy: clinical treatment

Gaseous gangrene

Various clostridia

At the onset of infection, anaerobic milieu with low redox potential and necrotic tissue required (e.g., open crushed soft parts)

Ubiquitous, in soil, in intestines of humans and animals

Highly lethal, fatal without treatment (1-3 days)

No known specific antitoxin to date, gaseous gangrene serum controversial

Therapy: clinical treatment

Japanese B encephalitis

Arbovirus

From mosquitoes (Culex spp.); person-to-person; mammal-to-person

Endemic in China, India, Japan, Korea and neighbouring countries

Mortality to 30%; partial cure to 80%

Mosquito prevention, active immunization possible;

Therapy: symptomatic

Leptospirosis

Various leptospira

Urine of infected wild and house animals (mice, rats, field rabbits, foxes, dogs), skin injuries, mucous membrane

Endemic worldwide areas

From asymptomatic to multi-organ infestation

Appropriate protective clothing when around infected animals, immunization not possible

Therapy: penicillin, tetracycline

Lyme disease

Borrelia burgdorferi

Ixodes ricinus tick, other insects also suspected

Europe, North America, Australia, Japan, China

Numerous forms of sickness, complicating organ infection possible

Personal protective measures before tick infectation, immunization not possible

Therapy: antibiotics

Meningitis, meningo-encephalitis

Bacteria (meningo-, pneumo-staphylococci and others)

Mostly airborne infection

Meningococci, meningitis epidemic, otherwise ubiquitous

Less than 10% mortality with early diagnosis and specific treatment

Personal hygiene, isolate infected persons

Therapy: antibiotics

 

Viruses (Poliomyelitis, Coxsackie, Echo, Arbo, Herpes and Varicella viruses)

Mucous and airborne infection (airways, connective tissue, injured skin), mice are source of infection in high percentage of cases

Ubiquitous incidence

High mortality (70%) with herpes infection

Personal hygiene; mouse prevention

Therapy: symptomatic, among varicella effective specific treatment possible

 

Mushrooms

Mostly systemic infections

Ubiquitous incidence

Uncertain prognosis

Therapy: antibiotics (protracted treatment)

 

Mycobacteria (see tuberculosis)

 

 

 

 

 

Leptospira (see leptospirosis)

 

 

 

 

Malaria

Various plasmodia (tropica, vivax, ovale, falciparum, malariae)

mosquitoes (Anopheles species)

Subtropical and tropical regions

30% mortality with M. tropica

Chemoprophylaxis possible, not absolutely certain, mosquito nets, repellents, clothing

Therapy: medication

Onchocerciasis

Loiasis

Dracunculiasis

Dirofilariasis

Various filaria

Flies, water

West and Central Africa, India, Pakistan, Guinea, Middle East

Highly varied

Fly control, personal hygiene

Therapy: surgery, medication, or combined

Ornithosis

Clamydia psittaci

Birds, especially parrot varieties and doves

Worldwide

Fatal cases have been described

Eliminate pathogen reservoir, immunization not possible

Therapy: tetracycline

Papatasii fever

Flaviviruses

Mosquitoes (Phlebotomus papatasii)

Endemic and epidemic in Mediterranean countries, South and East Asia, East Africa, Central and South America

Mostly favourable, often long convalescence, sickness leaves far-reaching immunity

Insect control

Therapy: symptomatic

Rabies

Rhabdovirus

Bite from infected wild or house animals (saliva highly infectious), airborne infection described

Many countries of the world, widely varying frequency

Highly lethal

Active (including after exposure) and passive immunization possible

Therapy: clinical treatment

Recurrent fever

Borrelia-spirochetes

Ticks, head and body lice, rodents

America, Africa, Asia, Europe

Extensive fever; up to 5% mortality if untreated

Personal hygiene

Therapy: medication (e.g., tetracycline)

Tetanus

Clostridium tetani

Parenteral, deep unclean wounds, introduction of foreign bodies

Ubiquitous, especially common in tropical zones

Highly lethal

Active and passive immunization possible

Therapy: clinical treatment

Trichuriasis

Trichuris trichiura

Ingested from eggs that were incubated 2-3 weeks in the ground

Tropics, subtropics, seldom in the United States

Only serious infections display symptoms

Personal hygiene

Therapy: medication possible

Tsutsugamushi fever

Rickettsia

(R. orientalis)

Associated with mites (animal reservoir: rats, mice, marsupials); infection from working on plantations and in the bush; sleeping outdoors especially dangerous

Far East,

Pacific region, Australia

Serious course; mortality close to zero with timely treatment

Rodent and mite control, chemoprophylaxis controversial

Therapy: timely antibiotics

Tuberculosis

Various myco-bacteria (e.g., M. bovis, avium balnei)

Inhaling infected droplets, contaminated milk, contact with infected wild animals (e.g., mountain goats, deer, badgers, rabbits, fish), wounds, mucous membranes

Ubiquitous

Still high mortality, depending on organ infected

Active immunization possible, chemoprophylaxis disputed

Therapy: clinical treatment, isolation, medication

Tularemia

Francisella tularensis

Digestive tract wounds, contaminated water, rodents, contact with wild rabbits, ticks, arthropods, birds; germs can also enter through uninjured skin

Ubiquitous

Varied forms of sickness; first sickness leads to immunity; mortality with treatment 0%, without treatment appr. 6%

Caution around wild animals in endemic areas, disinfect water

Therapy: antibiotics

Yellow fever

Viruses

Bite from forest mosquitoes, which are infected from wild primates

Central Africa, South and Central America

Up to 10% mortality

Active immunization

 

Poisonous Snakes

Poisonous snakebites are always medical emergencies. They require correct diagnosis and immediate treatment. Identifying the snake is of decisive importance. Due to the wide range of varieties and territorial particularities, the knowledge necessary for this can be acquired only locally, and for this reason cannot be described in general. Blocking veins and local incisions (only by experienced people) are not undisputed as a first-aid measure. A prompt dose of a specific antidote is necessary. Attention must also be paid to the possibility of a life-threatening allergic general reaction to the antidote. Injured persons should be transported lying down. Do not administer alcohol or morphine.

Spiders

Few poisons have been researched to date. An attempt should absolutely be made to identify the spider (of which knowledge can be acquired only locally). Actually, there are no valid general first-aid measures (possibly administer available antiserums). In addition, what was said about poisonous snakes applies analogously.

Bees, Wasps, Hornets, Ants

Insect poisons have very different effects, depending on the locale. Removing the stinger from the skin (and being careful not to introduce more poison during handling) and local cooling are recommended first-aid measures. The most-feared complication is a life-threatening general allergic reaction, which can be provoked by an insect sting. People allergic to insect poisons should, therefore, carry adrenalin and an injectable antihistamine with them.

Scorpions

After injury, a dose of antidote should absolutely be given. Local knowledge of first aid is necessary.

 

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