Nosema or Nosemosis is a parasite disease that is triggered by microsporidian called Nosema Apis that manages to invade the medium intestinal tract of honey bees, producing toxins that affect the bee's health. The Nosema Apis sporulates in the intestines and it is eliminated by means of excrements inside the hive. In the case of strong bee families the nosema disease might be latent but it can become acute when the biological equilibrium of the family is disturbed due to certain causes such as:
1. a weak bee family
2. a long hibernal period not followed by cleansing flights
3. honeydew honey
4. artificial bee food that contains lots of processed types of floor
5. excessive hive humidity

The nosema disease can be identified only thorough a thorough laboratory analysis. This disease affects the bee families in late winter and spring but sometimes even in autumn. It is considered to be a disease caused by poor sanitary conditions within the hive. The nosema is spread from one family to another through food, honey, pollen, honeycombs and contaminated beekeeping tools.

Nosema symptoms

It is very difficult to spot the symptoms if the disease is in its latent form. The bee colonies affected by nosema are restless, do not develop properly and have a high mortality rate. The presence of tiny diarrhea spots on honeycomb and in various parts of the hive is also a sign of nosema. If the disease is in its acute form then the symptoms are: a much reduced activity during spring or after cold and rainy summer days and massive hive depopulation in spite of the healthy brood. The honey bees affect by nosema have light brown diarrhea and a swollen abdomen. These bees cannot fly, they shiver, crawl at the hive entrance, paralyze and in the end they die. Honeybees that die of nosema have their legs swirled under their thorax and the wings spread. When nosema is accompanied by diarrhea it is very difficult to make the distinction between bee dysentery and nosema.

The hive entrance, the hive walls, the combs and all the objects around the hive are covered by brown diarrhea spots. The queen bees infested with nosema are initially agitated and then become apathetic and have a reduced mobility. They start falling from the combs, they no longer lay eggs nor feed themselves and eventually they die. The queen bees do not suffer from diarrhea on the contrary they are constipated. The higher the infestation degree, the more constipated they are.

The intestinal tract of the nosema infest honeybees can be examined after their head is removed. A microscope is not needed to observe that the intestine presents certain macroscopic mutations. The middle intestinal tract is thicker with a white opaque color and no transversal striations. Since these symptoms are typical for other diseases too, a precise diagnosis is not possible in the absence of a laboratory examination.


Nosema can be treated by giving the infested honey bees Protofil or antibiotics. The Protofil is medicine whose composition prevents the development of Nosema Apis, inhibits the pathogen intestinal flora and stimulates the secretion of digestive enzymes in adult bees and larva. It can be administered in sugar syrup (17ml/1liter of syrup) or in a sugary paste (3 ml/kg).

Nosema can also be treated with an antibiotic (fumagiline), having the commercial name of Fumidil B. This medicine can be purchased under a phial form of 25 g. A single phial can be used to treat five bee families. This medicine can be administered in syrup, sugary paste or sugar cake depending the season. One gram of Fumidil B has to be mixed with one liter of sugar syrup. Each bee family affected by nosema has to be given 10 doses of this medicinal syrup every other day. A dose has to be equal to 50 ml.

If such medicines are not available then the beekeeper can use herbal tea made of mint, chamomile, basil, rattles or yarrow. The hives affected by nosema must be sanitized. In order to do this the beekeeper must throw away the old honeycombs or those stained with diarrhea. The hives have to be cleaned with a solution made of 50 grams of laundry soda and one liter of warm water. It is advisable to fight only for the strong, well developed bee families. Beekeepers also increase the hive ventilation in order to cure bee families from nosema.

Honey bee disease > Acarine mites > Acute bee paralysis virus > American Foulbrood > Black Queen Cell Virus > Bee louse> Chalkbrood > Chilled Brood > Chronic Bee Paralysis Virus > Cloudy wing virus > Colony Collapse Disorder > Deformed Wing Virus > Bee Dysentery > European Foulbrood > Israelii acute paralysis virus > Kashmir Bee Virus > Nosema > Sacbrood virus > Bee septicemia > Stonebrood > Varroa Mite >

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