In the process of drawing wax, the bees manipulate the soft wax scales with their legs and mandibles. Bacteria/spores of diseases are locked into the wax during this process. Putting fresh foundation in the brood box helps keep your hive clean of disease. Twice a year, once in spring and again in autumn, go to the brood box and remove the 2 out-side frames (normally full of honey). Starting from the centre, push the remaining frames outwards, and insert 2 new frames with foundation, into the centre.
Types of Disease:
In Australia, there are 5 common diseases:-
Sacbrood : A virus that effects the larvae soon after being capped. Most prevelent in spring. The virus prevents the larvae shedding its skin during moulting, hence the thick 'sac-like' appearance of Sacbrood. Requeening if often the best solution.
Chalkbrood : A fungal disease which affects larvae 3 - 4 days old and transforms it into a white chalk like mummy. Stress such as cold wet conditions, poor nutrition or a failing queen often trigger the disease. Minimise the size of the hive, to assist temperate control, may help.
EBD or EFB - European Brood Disease is caused by a bacteria and is most common in early spring. The dead larvae have a watery pasty appearance, changing yellow then brown to black. The odour ranges from sour to faecal, and the dead larvae may rope (similar to AFB).
AFB - Americal Foulbrood is caused by a bacteria, adn regarded as the most serious disease by Beekeepers. The AFB spore is a string of DNA which can remain viable for 40 years, and is highly contageous. The disease kills larvae after they are capped. Identified by the roping of the dead larvae material, the fetid smell and the black perforated cappings on the brood cells.
Nosema : A disease of adult bees resulting in weak colonies. It is present in most bee hives at all times, and outbreaks often follow periods of stress - poor nutrition; cold wet weather;
Kashmir Disease : A viral disease with results similar to European Brood Disease, but rarely encounted.
NB - see also the article in 'NEWS' on CCD -Colony Collapse Disorder