Wednesday, 5 October 2011

The unholy trio of the sandpit - Toxoplasmosis, Meliodosis and Silicosis Pt 2

The summaries I will present in the next few posts are excerpts from my book "Garden maintenance for playspaces" and are referenced through the Centre for Disease Control (CDC), USGS, International Agency for Research on Cancer (IARC), The Children's Environmental Health Center, Mount Sinai School of Medicine. New York, Occupational Safety and Health Administration (OSHA), OEHHA’s (Office of Environmental Health HazardAssessment) & the Northern Territory State government


Part 2 - 
Melioidosis
Summary
1) Melioidosis, also called Whitmore's disease, and is caused by the bacterium Burkholderia pseudomallei.
2) It can infect humans and animals.
3) It is predominately a disease of tropical climates, especially in Southeast Asia and northern Australia. The bacteria causing melioidosis are found in contaminated water and soil. It is spread through direct contact with the contaminated source.
4) Melioidosis infection can be treated with the use of appropriate medication.
5) In those geographic areas mentioned, childcare services can minimised the risk of Meliodosis by:
· Ensuring that your sandpit/digging patch drains well after rain, has a cover that allows evaporation, that the sand/soil is turned over after rain to encourage drying (UV radiation will kill or a sanitising agent- see below)
· Check that any sores/cuts on children are covered with waterproof dressings,
· Ensuring all children wear waterproof shoes when playing outdoors,
· Children should avoid playing in muddy areas, wet sandpits or places where water has pooled in grassy areas or where grassed areas are boggy (*note point 2 above, this is only relevant for those climates that support the bacteria).
· Playing on wet grass is considered to be low risk for acquiring melioidosis. Sandpits which are dry or dry enough to comfortably play in are also low risk[i].

Transmission
Humans and animals are believed to acquire the infection by inhalation of contaminated dust or water droplets, ingestion of contaminated water, and contact with contaminated soil, especially through skin abrasions. It is very rare for people to get the disease from another person. While a few cases have been documented, contaminated soil and surface water remain the primary way in which people become infected.


Signs and Symptoms
There are several types of melioidosis infection, each with their own set of symptoms. However, it is important to note that melioidosis has a wide range of signs and symptoms that can be mistaken for other diseases such as tuberculosis or more common forms of pneumonia.
· Acute Localized Infection: Fever, General Muscle Aches
· Pulmonary Infection: High fever, Headache, Anorexia, General muscle soreness, Chest pain, Cough,
· Acute Bloodstream Infection: Fever, Headache, Respiratory distress, Abdominal discomfort, Joint pain, Muscle tenderness, Disorientation
· Disseminated Infection: Fever, Weight loss, Stomach or chest pain, Muscle or joint pain, Headache, Seizures

The time between an exposure to the bacteria that causes the disease the emergence of symptoms is not clearly defined, but may range from one day to many years; generally symptoms appear two to four weeks after exposure. Although healthy people may get melioidosis, the major risk factors are Diabetes, Liver disease, Renal disease, Thalassemia, Cancer or another immune-suppressing condition not related to HIV.

Risk of Exposure
While melioidosis infection has taken place all over the world, Southeast Asia and northern Australia are the areas in which it is primarily found. In the United States, confirmed cases reported in previous years have ranged from zero to five and have occurred among travellers and immigrants coming from places where the disease is widespread.

The greatest numbers of melioidosis cases are reported in Thailand, Malaysia, Singapore, and Northern Australia. In addition, it is now believed to be widespread in Papua New Guinea, Most of the Indian subcontinent, Southern China, Hong Kong, Taiwan. Though rarely reported, cases are thought to frequently occur in Vietnam, Indonesia, Cambodia, Laos, Myanmar (Burma). Outside of Southeast Asia and Australia, cases have been reported in The South Pacific (New Caledonia), Sri Lanka, Mexico, El Salvador, Panama, Ecuador, Peru, Guyana, Puerto Rico, Martinique, Guadeloupe, Brazil, Parts of Africa and the Middle East,

Treatment
When a melioidosis infection is diagnosed, the disease can be treated with the use of appropriate medication.
The type of infection and the course of treatment will impact long-term outcome. Treatment generally starts with intravenous (within a vein) antimicrobial therapy for 10-14 days, followed by 3-6 months of oral antimicrobial therapy.

In tropical environments melioidosis bacteria live deep in the soil during the “Dry”, but are found in surface water and mud after heavy rainfall in the “Wet”. In addition, there is no vaccine to protect against melioidosis. For these reasons and others, preventing exposure can be difficult. However, there are things that can be done to help minimize the risk of exposure:
· Ensuring that your sandpit/digging patch drains well during after rain, has a cover that allows evaporation, that the sand/soil is turned over after rain to encourage drying (UV radiation will kill or a sanitising agent)
· Check that any sores/cuts on children are covered with waterproof dressings,
· Ensuring all children wear waterproof shoes when playing outdoors
· Children should avoid playing in muddy areas, wet sandpits or places where water has pooled in grassy areas or where grassed areas are boggy.
· Playing on wet grass is considered to be low risk for acquiring melioidosis. Sandpits which are dry or dry enough to comfortably play in are also low risk[ii].

Disinfection
Disinfecting playspace sandpits and digging patches can be completed with the use of numerous disinfectants including benzalkonium chloride, iodine, potassium permanganate, 1% sodium hypochlorite[iii]. Melioidosis is effectively killed by the commercial disinfectants such as Perasafe®[iv]. The microorganism can also be destroyed by heating to above 74°C for 10 min or by UV irradiation. Melioidosis is not reliably disinfected by chlorine[v].



[i] http://www.healthylivingnt.org.au/content/?action=getfile&id=705
[ii] http://www.healthylivingnt.org.au/content/?action=getfile&id=705
[iii] Miller, WR; Pannell, L; Cravitz, L; Tanner, WA; Ingalls, MS (1948). "Studies on certain biological characteristics of Malleomyces mallei and Malleomyces pseudomallei: I. Morphology, cultivation, viability, and isolation from contaminated specimens"
[iv] Wuthiekanun V, Wongsuwan G, Pangmee S, Teerawattanasook N, Day NP, Peacock SJ (2010). "Perasafe, Virkon and bleach are bactericidal for Burkholderia pseudomallei, a select agent and the cause of melioidosis".
[v] Howard K, Inglis TJJ (2003). "The effect of free chlorine on Burkholderia pseudomallei in potable water". Howard K, Inglis TJJ (2005). "Disinfection of Burkholderia pseudomallei in potable water"
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