Foulbrood

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Foulbrood is caused by Mellissococcus pluton bacterium. It propagates in the middle part of intestine of bees larvae. The size of bacteria is 0.5*1,0 micrometer. These organisms are lancet-shaped cocci that can exist either separately or in clusters. Bacteria are arranged in pairs, the ends looking at each other or thin flagellum. The bacteria are gram-positive.

Etiology

Preparing smears - the preparation made of dissolved water suspense from the middle part of larvae's intestine and is put on the microscope glass slide and is mixed with a 5% water solution of nygrozin. The material is spread over the glass slide over a few square centimeters and dried above the flame. For the bacteriological examination a microscope with high magnifying power.

Cultivation - small or recently died larvae can be used for isolation of Mellissococcus pluton bacterium. A bee larva can be dissected on a sterile glass slide of a microscope so that cuticle could be taken by by sterile pincers and stretched.

The contents of the middle part of an intestine is situated in transparent, peritrophic membrane. A part of it is often filled with bacteria- opaque as white as chalk clots. Bacteria Mellissococcus pluton can be taken. Sealed cells containing living larvae can sometimes be of dark brow color. In bee families infected by foulbrood the lower part of the cells with larvae is covered with Mellissococcus pluton. These organisms can be easily taken from this part of the brood. Mellissococcus pluton can be cultivated on a nutritious Bailey medium:

10 gr of glucose,

10 gr of yeast extract (Difco)

13 bgKN2PO4

20 gr of agar

add distilled water up to 1000ml.

PH is equal to 6,6. The nutritious medium is boil in autoclave and poured into Petri cups before the usage. The cultures should undergo anaerobe incubation at a temperature of 34C in Macintosh and Fildes vessels in the atmosphere of 5-10% CO2. Round convex opaque colonies of Mellissococcus pluton with a diameter of 1-1,5 mm are usually grow during 4 days. When the growth is considerably visible the edges of the cup are sealed and the culture can be kept for 6 months at a temperature of 40C. Bacteria Mellissococcus pluton is hardy for a long time if it is in a dry state. Dried smears from the middle part of an intestine can be preserved during 3 years at a room temperature.

Secondary infection

Bacterium eurydice is an ordinary attendant organism. This bacterium can be found in an intestine of any healthy bee larva. Sometimes it occurs in the intestine of infected bee larvae and can be mistaken for Mellissococcus pluton. Bacterium eurydice dies quickly in dead larvae. In the conditions necessary for Mellissococcus pluton life Bacterium eurydice forms thin flagellums propagates slowly.

Streptococcus faecalis can be also mistaken for Mellissococcus pluton, although both the organisms differ in the ways of cultivation and serologically. Streptococcus faecalis often occurs in infected larvae. Streptococcus faecalis causes a sour smell, which accompanies foulbrood. In dry state this bacteria can't stay alive for a long time. Streptococcus faecalis grows well in the conditions favorable for cultivation of Mellissococcus pluton. Small transparent colonies appear within 24 hours. In the presence of glucose PH of nutritious medium is reduced to 4,0. Acid presence is enough for hindering Mellissococcus pluton in vitro development. Streptococcus faecalis doesn't grow on larvae if there is no Mellissococcus pluton on them, so the presence of Streptococcus faecalis in large quantities can indicate foulbrood infection.

Another attendant foulbrood organism is Bacillus alvei. This organism grows on decomposing remnants of bee larvae. Bacillus alvei form resistant spores, that retain viability more than two years. In the conditions favorable for cultivation of Mellissococcus pluton Bacillus alvei propagates slowly or doesn't develop at all. Bacillus forms booming transparent colonies, some of which move slowly. The cultures have a specific musty smell, which indicates the presence of foulbrood. Bacillus alvei is widely spread in be families, where Mellissococcus pluton is constantly present in a locality.

The course of the disease

The course of the disease in bee families

The most frequent signs of the disease is the death of larvae in sealed cells. The disease often suddenly stops before the end of active season. Infected bee families show few symptoms, but the death of larvae is typical and characteristic. Infected by foulbrood bee larvae usually die 1-2 days before being sealed in cells, or soon after it. in some bee families in Australia the cases of 90% death of larvae were stated.

The course of disease of separate larva.

Mellissococcus pluton grows only in the intestine cavity and stops growing after a larva is dead. In dead larvae Mellissococcus pluton can be found in other parts of the body. Sometimes infected larvae successfully pass through the stage of pupae and hatch. Before developing into pupae the contents of the middle part of the intestine is discharged together with Mellissococcus pluton , all the bacteria are alive.

Spontaneous recovery

Worker bees can appear soon after larvae have hatched and destroyed infected larvea. The disease seem to recede and bee families manage to recover on their own but sometimes relapses occur. Foulbrood appears annually. In some cases bee families are considerably enfeebled by foulbrood. In South Australia eight out of ten infected bee families if not treated either died or remained infected.

Suppressing infection

International institute of inflectional diseases recommends that an international vetenary certification should be demanded confirming that honey combs with bee brood don't demonstrate any clinical signs of foulbrood on the day of sending.

In Poland as well as in many other countries announced regulations about suppressing bee diseases in bee families of 1946 give right to suppress foulbrood in bee families also. Every beekeeper who suspects his bee family of being infected by foulbrood should notify local vetenary authorities about the disease. Local veterinary departments will check officially an infected bee family or send samples of honey combs to a laboratory to diagnose the disease. Infected bee families should be treated with antibiotics. Hives and equipment should be sterilized with the help of soldering iron. The area with the radius of 5 km from an infected family should be observed. Specially trained bee keepers help local vetenary authorities. Any transportation of a bee family is allowed only after the necessary testing. Quarantine measures are taken until all the bee families in an infected apiary are cured from foulbrood.

Infected bee families can be treated with streptomycin. The dose for a bee family is 5 gr of active streptomycin for one feeding. This antibiotic can be given in frame feeders with a liter of sugar. Three feeding within 7 days are recommended. Oxytetracycline ( terramycin) can control foulbrood. If antibiotics are misused or they are used inopportunely they can contaminate honey.

Prophylaxis

All bee keepers should know the way a healthy brood looks like so that they could distinguish it from an infected one. In order to prevent appearance of infection in some cases broodnests shouldn't be exchanged between the families. Old combs shouldn't be also bought. Honey used for feeding bees shouldn't be taken from doubtful sources. Bee families should be bought only from healthy bee families in healthy apiaries. Frames should not be put on the ground. If used hives have been purchased they should be sterilized. Hives should be arranged in such a way so that there were no possibility for bees to get into a neighboring hive. If a bee families dies during winter, the hive should be closed until the examination of honey combs is carried out.

Bees can fly to neighboring countries that' why preventive measures against spreading of bee diseases are especially important at boundary regions.

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English translation © Irina Yelsukova