Romanian apiaries face a range of bacterial, fungal, viral, and parasitic diseases. Most experienced beekeepers in the country encounter the same four or five conditions repeatedly across their careers. This guide covers the ones that appear most frequently: nosemosis, American foulbrood, European foulbrood, sacbrood, and chalkbrood — with notes on what distinguishes each in the field and what responses are available.
Varroa is not listed here because it is covered in detail in the varroa treatment guide. The diseases below are independent of mite load but in practice often appear in colonies already weakened by heavy varroa infestation.
Nosemosis (Nosemoza)
Nosema apis and Nosema ceranae are microsporidian fungi that colonize the midgut epithelium of adult bees. Unlike most bee diseases, nosema shows no obvious signs in the brood — the comb can look perfectly normal while the adult population depresses around it. This makes it one of the more insidious conditions in the spring inspection cycle.
How it presents
- Slower-than-expected spring build-up despite good food stores and an apparently laying queen
- Brown or yellow fecal streaks on the landing board, entrance face, or inner cover — most visible in early spring after a long confinement period
- Bees crawling on the ground near the hive entrance, unable to fly or flying in tight erratic circles
- In some cases, no external signs at all — confirmed only by microscopic examination of the gut contents of 30–40 adult bees
Conditions that promote it
Cold, wet springs delay cleansing flights and allow spore counts in the gut to build to damaging levels. Damp wintering conditions — condensation dripping onto the cluster — also favor nosema. In Romania, the late-winter/early-spring period is the highest-risk window, corresponding to when colonies are confined but generating heat and moisture inside the box.
Response options
No veterinary-registered nosema-specific treatment is available for beekeepers in most EU countries, including Romania — Fumagillin was withdrawn from the EU market. Management responses focus on eliminating the conditions that favor the parasite:
- Replace old dark combs with fresh foundation — spores accumulate in comb wax
- Improve hive ventilation to reduce winter condensation; tilt hives slightly forward so moisture drains toward the entrance
- Replace queens in seriously affected colonies — younger queens support faster colony turnover and bees in heavily infected hives rarely recover fully without queen replacement
- Thymol-based treatments applied for varroa have some secondary inhibitory effect on Nosema ceranae and can be a useful coincident benefit when treating for varroa in late summer
American Foulbrood (Loca americană)
American foulbrood (AFB), caused by Paenibacillus larvae, is the most serious bacterial disease affecting bee colonies worldwide. In Romania it is a notifiable condition — confirmed outbreaks must be reported to the local veterinary authority. The bacterium forms extraordinarily persistent spores that survive in unused equipment for four decades or more.
How it presents
- Sunken, perforated, darkened cappings on sealed brood — a "greasy" or concave appearance rather than the slightly domed look of healthy capped brood
- The ropiness test: insert a matchstick or twig into a suspect cell, stir gently, and withdraw slowly. If the dead larva forms a thread (rope) of 1–3 cm as the stick is pulled out, this is strongly indicative of AFB
- A distinctive sour, glue-like odor described as resembling decaying wood glue or fermenting fruit — present in advanced infestations
- Dark brown scale (dried larval remains) lying flat in cells after the ropy stage passes — at this point the scale contains billions of infective spores
Spread and prevention
AFB spreads through robbing behavior, swarms, and beekeeper equipment. The most dangerous transmission pathway in a multi-colony apiary is the beekeeper's own hive tool and hands moving between hives without disinfection. Flame the hive tool between colonies; wash hands with soap; do not move frames between colonies without checking for disease first.
Response
In Romania, confirmed AFB requires reporting to the local Circumscripție Sanitar-Veterinară. The legally mandated response for confirmed cases is destruction of the colony and disinfection or burning of equipment. Oxytetracycline was historically used but is no longer approved in the EU for beekeeping. There is no effective treatment; the only response that reliably eliminates the spore reservoir is heat disinfection of equipment (flame until very hot) or replacement of all combs.
Finding one confirmed AFB case means every colony in the apiary needs examination. The disease is rarely in just one hive by the time it is visually obvious.
European Foulbrood (Loca europeană)
European foulbrood (EFB), caused by Melissococcus plutonius, is less serious than AFB but more common in Romanian apiaries during nutritional stress periods. Unlike AFB larvae, which die after cell capping, EFB larvae typically die before or just at capping, making the visual appearance distinctly different.
How it presents
- Larvae that appear twisted or melted in their cells rather than lying in the normal curled C-shape — most visible in uncapped cells
- Affected larvae turn yellow, then brown, with a rubbery texture initially; later they dry to a brown scale that is removable (unlike AFB scale, which adheres firmly to the cell wall)
- A mildly sour smell is present in heavily infected combs, but it is less distinctive than AFB
- The ropiness test is negative — unlike AFB, the dead material does not stretch
Conditions that promote it
EFB increases sharply during periods when the colony's population of nurse bees is insufficient to maintain brood temperature and feeding. Summer dearth periods in July are a common trigger in Romanian lowland apiaries. Protein deficiency — lack of pollen income — is the most frequently observed predisposing condition.
Response
Mild EFB outbreaks in nutritionally stressed colonies often resolve when the stress is removed: a pollen flow arrives, supplemental protein is provided, or the dearth period ends. More severe cases benefit from requeening with a younger, more prolific queen. No chemical treatment is registered for EFB in the EU.
Sacbrood (Boala puietului îngrădit)
Sacbrood is a viral disease caused by Sacbrood virus (SBV). It is common and generally self-limiting — colonies with strong populations usually clear the infection without intervention. It is worth knowing what it looks like because it can be mistaken for AFB or EFB on a casual inspection.
How it presents
- Dead or dying larvae found in capped cells — cappings are often perforated or sunken as with AFB, but the larval contents are different
- The larva does not decompose to a ropy mass; instead the skin remains intact and contains a watery fluid — the "sac" that gives the disease its name. Pick up the larva with a toothpick and it holds its shape as a fluid-filled bag
- Dried sacbrood larvae form a curved, boat-shaped scale that is easily removed from the cell — the upturned head end gives the scale a characteristic gondola appearance
Response
Strong colonies typically recover from sacbrood without intervention once the colony population builds. Requeening accelerates recovery by introducing a break in the brood cycle and a change in brood-pheromone profile. There is no registered antiviral treatment.
Chalkbrood (Ascosferoza)
Chalkbrood is caused by the fungus Ascosphaera apis and produces hard, white or grey chalk-like mummies in affected cells or on the landing board.
How it presents
- White or grey/black hard mummies in cells or ejected to the landing board by house bees attempting to clean the hive
- Affected cells may have perforated cappings or appear sunken
- More common in damp spring conditions and in colonies with poor bottom ventilation
Response
Improve hive ventilation. Replace queens from colonies with persistent chalkbrood; susceptibility has a genetic component and some queen lines show consistently lower incidence. Old damp comb should be replaced. As with many fungal conditions, dryness is the primary management tool.
Disease reporting in Romania
Romanian legislation requires beekeepers to report suspected American foulbrood and certain other notifiable diseases to the local Circumscripție Sanitar-Veterinară de Circumscripție (CSVC). Annual sanitary registration of apiaries is also mandatory and provides access to the national beekeeping support programs. The national veterinary authority (ANSVSA) publishes guidance on disease response at ansvsa.ro.