Most Common Fungal Aeroallergens

A comprehensive illustrated manual of the air-spora was recently published by Lacey and West (2006). The commonest fungal allergenic species belonging to the Zygomycetes are Rhizopus nigricans (black bread mould) and Mucor racemosus. Two significant allergenic ascomycetes are Saccharomyces cerevisiae (baker's yeast) yeast and Chaetomium indicum. In addition, skin sensitivity to conidia of powdery mildew, Microsphaera alvi has been reported.

Among the basidiomycetes, known allergenic fungi belonging to mushrooms and bracket fungi are Pleurotus ostreatus, Ganoderma lucidum, Geaster saccatum and Agaricus. Other allergenic species are Ustilago and Urocystis (Smut fungi - Ustilaginales).

By far the commonest highly abundant airborne fungi belong to Deuteromycetes (Fungi Imperfecti). Some of these genera are: Phoma, Aspergillus, Penicillium, Botrytis, Monilia, Trichoderma, Alternaria, Cladosporium, Helminthosporium, Nigrospora, Curvularia, Fusarium, Epicoccum and Sporobolomyces.

SEASONAL VARIATION

Unlike pollen, there is no sharp seasonal variation in the atmospheric fungal air-spora. However, some variations occur due to extreme weather factors. All the dominant fungi: Aspergillus niger, Aspergillus flavus, Cladosporium spp., Penicillium oxalicum and Alternaria spp. were found during all the four seasons: summer, South West monsoon, North East monsoon and winter. However, the total concentrations of dominant fungal spores in the indoor and outdoor environments were maximum during the monsoon seasons in South India. In a recent study in Kerala, Govind (2004) reported the following concentrations of fungal spores:

Indoor - 10666 CFU/m3 Outdoor - 7700 CFU/m3 In winter: Inside 3154 CFU/m3

Outside 3370 CFU/m3 In summer: Inside 3154 CFU/m3 Outside 2718 CFU/m3

Thus, throughout indoor concentration was more than outdoor. Govind (2004) has also described morphology of most commonly occurring airborne fungal spores. Some of them have been scanned under SEM, which have been illustrated in Figs. 16.1, 16.2, 16.3 and 16.4.

Agashe et al. (1983) have reported high fungal concentration at high humidity. Several researchers have reported high fungal concentration at low temperatures 20-30°C. With the increase in temperature 32-35°C, concentration of air-spora decreases. Some work has been done on the seasonal variations of fungal aeroallergens in specific occupational indoor environments.

Aspergillus Fumigatus Conidiophore Sem
Fig. 16.1 SEM of conidiophore and conidia of Aspergillus flavus.
Cladosporium Spore Sem
Fig. 16.4 Highly enlarged SEM showing conidia of Aspergillus niger (Figs.16.1 to 16.4 from Govind, 2004).

In Bakery environment: Aspergillus niger dominated in a summer, South West monsoon and North East monsoon. Cladosporium spp. recorded the highest count in winter. Relative humidity (Rh) had a significant effect on the concentration of fungal spore deposition.

SCOPE OF FUNGAL AEROALLERGEN RESEARCH

Many asthmatic patients develop nocturnal attacks and are unable to sleep at night in their bedrooms. The identification and quantification of the fungal spores prevalent in occupational sites and in asthmatic patients' bedrooms along with their clinico-immunological studies are of immense help to the clinicians to identify the offending allergens and provide effective treatment.

The clinician can inform asthmatic patients if they have fungal allergy and the patient can be advised to take necessary measures against fungal exposure. Accurate diagnosis and treatment by an experienced and trained allergologist will help the patients to obtain relief from allergic symptoms, keep in good health and lead a normal life. It is imperative that both the diagnosis and treatment will yield better results if standardized extracts are used. Currently, the best method available is to detect antigen sensitivity by skin testing and provide allergen immunotherapy for immunomodulation in asthmatic patients.

Data on seasonal and annual prevalence of fungal species recorded in detailed aerobiological studies will be of immense importance to clinicians, and which will serve as a ready reckoner for them to select the appropriate fungal extract for the diagnosis and treatment of allergic rhinitis and asthma in patients.

This knowledge obtained from an atmospheric survey of fungal aeroallergens is useful in compiling spore calendars and prediction models of airborne fungal spore occurrence. It is necessary to carry out a survey of airborne pollen and fungal spores at three year intervals as the dynamics of environmental substances are dependent on several factors, including weather parameters which continuously change. The research will be helpful in compiling a fungal spores calendar and making it available to the clinicians for its use in allergy diagnosis. The fungal spores calendar indicates the occurrence of most predominant and common types of airborne fungal spores in the atmosphere.

Fungal Spore Survey

Aerobiologists have not lost any time in carrying out very useful indoor and outdoor airborne surveys of New Orleans, U.S.A., soon after the catastrophic Hurricane Katrina, on August 29, 2005. Following Hurricane

Katrina, several New Orleans homes remained flooded for weeks. Thus, the indoor atmosphere was ideal for microbial growth, responsible for significant risk of respiratory exposures for residents upon re-entry to their dwellings. Bioaerosol concentrations in flood-damaged homes, were extremely high and health surveys indicated an increase in allergy and upper airways infections (Muilenberg et al. 2006).

Dumon et al. (2006) carried out intensive surveys of moulds in the dwellings after they were flooded on December 2-5, 2003. The protocol in their investigation included a visual inspection of the dwellings, the computation of the mouldy area in each room and a sampling of visible growths, using the paper-gummed technique. They found that there was over representation of Alternaria and Stachybotrys chararum. They certainly cause health hazards as these species are known to produce mycotoxins. In addition, Aspergillus spp. and Penicillium spp. were also encountered in large numbers.

The aftermath of the catastrophic event of the post Katrina flooding of homes in New Orleans area resulted in increased regional total mould spore levels. The health effects of elevated levels of airborne fungi were recently discussed by Levetin et al. (2006). They reported mean concentrations of total mould spores as 5,762 m3 in 2003, 4,690 m3 in 2004 and 7,396 m3 in 2005. During this period there was a tremendous increase in the representation of Penicillum/Aspergillus, Cladosporium, Chaetomium and Eurotium ascospores and Stachybotrys conidia.

Fungal succession and airborne concentrations of indoor and outdoor fungi in post hurricane Katrina in New Orleans, Louisana, U.S.A. were thoroughly investigated by Hjelmroos-Koski and Solomon (2006). Katrina, a category 4 hurricane which hit the Louisiana-Mississippi border and New Orleans on August 29, 2005 resulted into flooding of an estimated 120,000 homes (80% of the city).The homes remained flooded for several weeks.They were reflooded three weeks later when category 3 Hurricane Rita hit the city, which, enhanced the indoor airborne fungal spore population. During this period, the average daily mould spore concentration ranged from 21,000 to 102,000 spores m3 of outdoor air and 11,000-645,000 m3 of indoor air.

FUNGAL SPORE CALENDAR OF BANGALORE, INDIA

Agashe and Vidya (1999) compiled an excellent fungal spore calendar of Bangalore city for the year 1997 (Fig. 16.5). They had used the most efficient air sampler known as rotorod sampler (model 40), which has been described in detail in Chapter 13 above.

An aerobiological survey carried out by them for the compilation of fungal spore calendar, brought to light 70 fungal spore types representing

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Alternaria

Ascos pores

Aspergillus Penicillium Basidios pores

Clodosporium Cercospora Curvularia

He/mintho spohum

Nigrospora Smut spores

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

C = 100 - 499 Fungal spores

D = 500 - 999 Fungal spores

E = 1000 - 4999 Fungal spores

Fig. 16.5 Percentage contribution of predominant fungal types in Bangalore atmosphere during 1997.

three major groups of fungi: Ascomycotina, Basidiomycotina and Deuteromycotina. As expected, Deuteromycotina constituted the largest fraction of airborne spores accounting for 71% of the catch. It was represented by commonest genera such as Cladosporium, Alternaria, Aspergillus, Penicillium, Nigrospora, Helminthosporium, Cercospora and Curvularia.

The fungal spore calendar depicted in the pie chart (Fig. 16.6) shows that the incidence and concentration of fungal spores varied from month to month during 1997. The highest monthly concentration (Fig. 16.7) was recorded in October with a total of 7,698 spores m-3 and the lowest was recorded in the month of August with 2,639 spores m-3 per cubic metre. The spores of Cladasporium, Alternaria, Cercospora, Helminthosporium, Aspergillus, Pencillium and Smut spores were found throughout the year though their peak varied from month to month. The peak season for Cladosporium occurred in April and July (Fig. 16.5). Aspergillus - Penicillium

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Hapishane Png

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Months

C = 100 - 499 Fungal spores

D = 500 - 999 Fungal spores

E = 1000 - 4999 Fungal spores

Fig. 16.5 Percentage contribution of predominant fungal types in Bangalore atmosphere during 1997.

Fig. 16.6 Monthly variation of the presence of fungal spores in Bangalore atmosphere for 1997.

Cladosporium Basidiospores Ascospores

Aspergillus - Pénicillium Smut spores 6 A/temaría Curvularia Cercospora

9 Helminthosporium

10 Periconia

11 Nigrospora

12 Others

Fig. 16.6 Monthly variation of the presence of fungal spores in Bangalore atmosphere for 1997.

7000-

6000

"E

4000'

3000'

2000-

1000-

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Fig. 16.7 Airborne fungal spore calendar of Bangalore for the year 1997 (Figs.16.5 to 16.7 from Agashe and Vidya, 1999).

established their peak in April. The major types of fungal spores showed an increase during monsoons associated with high relative humidity and maximum rainfall.

Agashe and Vidya further pointed out that the fungal spore calendars should be compiled and updated every year. The annual fungal spore calendar gives a clear picture of the change in trends of the peak and concentrations over the years. Allergy practitioners should keep a close watch on the fungal spore calendar, which well help in selecting antigenic extracts of fungal aeroallergens for skin testing to assess allergenicity. This will help in a better correlation of allergy symptoms of patients with atmospheric fungal spores and the proper diagnosis leading to treatment of allergy.

The atmospheric fungal spore monitoring was continued by Agashe and Mamlakatoi Khyderova who prepared fungal spore calendar of Bangalore for the year 2000-2002 (Fig. 16.8, Khyderova, M. 2003).

FUNGAL SPORg CALENDAR FOR BANGALORE 2OD0-2002

Tax on

JAN

FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

OCT

NOV

DEC

Cladosporium

29.80

20.82

15.35

51,12

73.55

26.56

36.06

8.93

39.14

27.12

3374

35.64

freer, a

19.18

13.11

9.05

10.13

6.63

8.24

7.64

6.00

1324

16.36

17.80

24.56

Smuts

22.35

14.63

8.55

7.31

4.05

6.96

7.56

6.42

4.85

7.11

18.32

22.30 14.57

Nigrospora

11.82

10.21

6.64

'9,05

-5.40

6.89

4.90

3 34

4.59

6.56

12.88

Alternaria

6.63

5.49

6.12

10.94

7.60

6.51

6.99

4.12

4.11

6.17

7.10

8.20

Ascospores

1.59

1.79

2.79

8.86

3.76

4.14

7.27

10.74

7.18

14 25

5.S4

2.59

Basrdiospores

1.95

1,24

2.16

2,12

3.93

3.04

5.23

7.17

6.16

17.52

10.40

6.61

Aspergillus

4.44-

3.43

3.62

5.65

3.71

3.39

3.52

1 47

3.17

2.10

4.97

9.06

Fair

1-25

Optimal

25-50

High

50-75

Very Hiqh

75-100

Fig. 16.8 Fungal spore calendar of Bangalore, India for the years 2000-2002 (From Agashe and Khyderova, 2003).

Fig. 16.8 Fungal spore calendar of Bangalore, India for the years 2000-2002 (From Agashe and Khyderova, 2003).

STUDIES ON FUNGAL AEROALLERGENS IN BANGALORE

While investigating the scope of aerobiological studies in immunotherapy in Bangalore, Agashe et al. (1983) had proved allergenicity to these fungal spores. The extracts of these fungal spores were tested on 172 nasobronchial allergy patients in Bangalore. The results of which are presented in the following table (Table 16.1). Helminthosporium showed 3+ reactions in five patients, Alternaria and Nigrospora showed 3+ reactions in three patients, whereas Cladosporium showed 3+ reactions in two patients.

Table 16.1

Sl.

Name of

Total No. of

Further grading of

No.

Antigen

Positive reactions

Positive reaction

1+ 2 +

3+ 4 +

1

Alternaria

7

4

3

2

Cladosporium

5

_ 3

2 _

3

Helminthosporium

8

3

5

4

Nigrospora

9

2 4

3 _

CIRCADIAN PERIODICITY OF FUNGAL AEROALLERGENS IN BANGALORE, INDIA

Circadian periodicity of predominant fungal spores in the atmosphere in Bangalore, was carried out by operating Volumetric - seven-day automatic Burkard spore trap from April 1988 to June 1988 at the Indian Satellite Research Organization's ISEC centre in Bangalore by Agashe et al. (2000).

The Burkard spore trap works on the suction principle. It has a suction capacity of 10 l/min. The pollen grains and fungal spores, which are sucked through a 2 mm orifice impact on the vaseline coated-tape wound around the rotating drum. After operating the trap for a week, the tape was removed from the drum and mounted on scale with seven equal parts. The exposed tape was cut into seven parts each representing one-days' catch. Each day's exposed tape was further divided into 12 equal parts to indicate the catch of pollen grains and fungal spores for every 2 hours interval. Scanned pollen and fungal spores were converted to number/m3. For the sake of convenience and proper understanding, the day was divided into six zones of 4 hours each, that is 2200-0200, 0200-0600, 0600-1000, 1000-1400, 14001800, 1800-2200 hours.

Among the 40 fungal spores recorded regularly the most dominant spores such as Alternaria, Cladasporium, Helminthosporium, Nigrospora and Smut were investigated for their circadian periodicity. The results were expressed as percentage of peak geometric mean concentration (Fig. 16.9).

The peak incidence of fungal spores was recorded between 1000 to 1800 hours, thus falling into a midday pattern. In April, Helminthosporium, Nigrospora, Cladosporium showed peak incidence between 10 am to 2 pm. In May and June, these fungal spores showed peak incidence between 2 pm to 6 pm. However, the maximum concentration of these fungal spores in the atmosphere was recorded at 4 pm.

FUNGAL SPORE CALENDAR FROM LEIDEN, THE NETHERLANDS

Nikkels et al. (1996) exhaustively studied microscopically identifiable airborne fungal spores from he Netherlands. They concentrated on non-viable fungal spores trapped by Burkard continuous volumetric sampler for a period of 10 years. They found that the spores of Deuteromycetes dominate the fungal air spora. Among them, in the descending order of predominance are: Cladosporium being the highest airborne contributor with an average annual total of the daily average of over 700,000. Botrytis, Ustilago and Alternaria are represented by annual total spore count between 20,000 to 30,000. The other spore types encountered in the atmosphere were Epicoccum, Erysiphe, Entomophthora, Torula, Stemphylium and Polythrinicum, all of these were represented by annual spore count of less than 10,000.

100 80 60 40 20

10 A

100 80 60 40 20

100 80 60 40 20

10 A

Cladosporium

Cladosporium

10 B

10 B

Helmlnthosporlumm

Helmlnthosporlumm

100 80 60 40 20

Aeroallergens

TIME OF THE DAY (HRS)

Fig. 16.9 Circadian periodicity of fungal aeroallergens in Bangalore, India. Percentages of the peak concentrations shown in A to E (From Agashe et al, 2000).

TIME OF THE DAY (HRS)

Fig. 16.9 Circadian periodicity of fungal aeroallergens in Bangalore, India. Percentages of the peak concentrations shown in A to E (From Agashe et al, 2000).

On the basis of a 10-year survey from 1980-1989, the fungal spore calendar depicted in Fig. 16.10, clearly shows the seasonal course in the airborne concentration of 10 selected spore types. The numerical key to the spore calendar is given in Fig. 16.11, while compiling the spore calendar they have followed the method i.e, presentation technique; calculated for 10 m3 of air, first introduced by Stix (1971) for pollen grains and later employed by Spieksma (1984).

Fungal Spore Calendar
Fig. 16.11 Key to the pollen calendar shown in Fig.16. column heights and experimental classes of average fungal spores (From Nikkels et al., 1996).

10 to show the relation between daily airborne concentration of

Essentially the spore calendar represented in Fig. 16.10 shows the annual appearance of the 10 spore types over the 36, 10-day periods. In this presentation, the logarithmic means for the 10 years of the average daily spore counts for the 10-day periods are calculated. Subsequently, these means are placed in exponential classes, which are plotted as columns in the graphically presented spore calendar.

AIRBORNE FUNGI OF SCOTLAND, U.K.

In addition to pollen, Eric Caulton carried out airborne fungal spores monitoring in Scotland during 2004. The peak of Alternaria spores was found to be in mid-August (Fig. 16.12).

Application of Aerobiology in Disease Forecasting

In fungi, the liberation of spores, their dissemination and dispersal and deposition are to a large extent dependent on meteorological factors. In this connection, the following aspects need consideration:

1. Plant pathogen dissemination

2. Plant pathogen dispersal

3. Plant pathogen deposition

4. Plant pathogen concentration in air

5. Plant pathogen that is primary inoculum

Alternaria spore count 2004

2000 1800 1600

3 iooo k

L, ffîfîflffîfîffîfîflffîfîffffîlltfttftftfttf

Fig. 16.12 Alternaria spore count in 2004 at Scottish Centre for Pollen Studies, Scotland, U.K. (From Eric Caulton, 2004).

Based on the above factors, one can derive the disease gradient and can take preventive measures.

Plant disease forecasting can be of two types: 1. Short period forecasting, 2. Long period forecasting.

DISEASES CAUSED BY FUNGAL AEROALLERGENS

Medical palynologists are concerned with interaction of pollen and spores with the human respiratory tract. Medical palynology is highly interdisciplinary. The medical community needs to know how much allergen is required to precipitate a disease response among subjects in variable health conditions. Such limits could be useful in the examination of the efficacy of drugs. Depending on their aerodynamic size, inhaled particles are deposited in three sections on the respiratory tract:

Mouth and nose - oropharyngeal deposition - most pollen and few mould spores >15 mm.

Throat - extra thoracic deposition

Lungs - thoracic deposition - most mould spores and few pollen < 15 mm. Large particles caught in the nose and mouth can result in allergic rhinitis and other allergic symptoms. The smaller penetrating particles may be involved in Airway Obstructive Disease (AOD) such as asthma.

Fungi mutate readily, filling any available niche. The allergen content often depends on growth factors such as temperature, time, availability of oxygen, size of inoculum and carbon source. Moulds are capable of producing allergies because they exhibit more varied numbers of proteins. For example, 56 proteins in Alternaria alternata are capable of inducing IgE antibodies. Sixty proteins have been identified in Cladosporium herbarum. This species contains 1 major allergen, 10 intermediate allergens and 25 minor allergens.

Frequent cross-reactivity among moulds is suspected because of multiple mould sensitivity among patients, but specific cross-reactivity studies are few. There is a great variation in the skin test results, mainly because of insufficient extract standardization, poor characterization, and possible lack of skin reactivity to some moulds.

Exposure to pollen and spores may cause disease reaction in different ways: when inhaled by immuno-compromised individuals, airborne spores such as Aspergillus fumigatus and Coccidioides immatus act as pathogens by colonizing lung tissue and reducing its function (Frankland 1977). Recovered individuals are then susceptible to secondary diseases, such as, chronic bronchitis and bronchiolitis. Colonizing fungal diseases have become increasingly prevalent with the advent of AIDS.

Fungi produce toxins and the best known is aflotoxin, a carcinogen associated with peanuts (Baxter et al., 1985). Exposure to toxinogenic fungi can cause a serious health risk including liver cancer to allergic individuals affecting the liver in particular (common among African population). Pollen and spores carry proteins, polysaccharides and lipids. When inhaled, some of these foreign materials, acting as antigens may stimulate the production of IgE antibodies. These antibodies cause the release of chemical mediators, histamines being the most important, from mast cells. Histamine triggers vasodilatation, sneezing and rhinitis, which are classical symptoms of hay fever.

FUNGAL SPORE ALLERGY

Airborne mould spores in indoor and outdoor atmosphere are known to cause mild to severe allergy, including asthma and rhinitis. Based on the indoor concentration of airborne mould spores , clinical and immunological studies were carried out in 85 children suffering from bronchial asthma and allergic rhinitis in Delhi, India by Sharma et al. (2006).

Antigenic extracts of predominant indoor fungal spores of Aspergillus spp, Alternaria, Cladosporium, Penicillum, Rhizopus and Cladosporium were used for skin testing and immunotherapy. In their study, they observed that the highest sensitization was to Alternaria alternata followed by Aspergillus fumigatus, Penicillum citrinum and Cladosporium cladosporites. Raised specific IgE was observed in cases with 2+ and above skin reactivity against fungi.

INDOOR FUNGI AND THEIR ALLERGY

Indoor mould spores and their occupational health hazards in the potato cold storage facility in West Bengal, India were investigated recently by Majumdar and Barui (2006). In a two-year (2002-2004) survey of potato cold storage houses, they found a preponderance of fungal spores of Aspergillus niger, Curvularia lunata, Echinobotryum, Alternaria alternata, Fusarium solani and Rhizopus nigricans.

Skin prick tests on 126 patients showed a high positive reaction (2+ or more intensity) to antigenic extracts of the above moulds. They also found that allergenic symptoms were pronounced during the monsoon and the summer season or whenever there was prolonged disruption of power supply.

FUNGAL ALLERGY AND EPIDEMIOLOGY IN ST. LOUIS AREA, U.S.A.

An extensive survey of airborne fungal spores was carried out by Lewis et al. (1975) from the Missouri area. This study was also backed by skin prick tests for evaluating fungal allergenicity. As many as 1,720 patients were prick tested for predominant fungal aeroallergens comprising Alternaria tenuis, Aspergillus spp. (a mixture of A. flavus, A. fumigatus, A. glaucus and A. terreus, Fusarium roseum, Helminthosporium sativum, Hormodendrum hordei (= Cladosporium), Penicillium chrysogenum, P. notanum, Phoma hybernica, Alternaria alternata and Drechslera.

Skin tests involving primarily the standard prick technique for immediate skin reactivity were recorded using the 0 to 4+ scale for allergens tested:

0 : no reaction or equivalent to control

1+ : erythema smaller than 10 mm in diameter

2+ : erythema larger than 10 mm in diameter

3+ : erythema larger than 10 mm in diameter plus weal larger than 10 mm in diameter

4+ : erythema larger than 10 mm in diameter and weal with pseudo-pods

It should be noted that the fungi from which extracts are administered are classified in four families in the fungi imperfecti: Dematiaceae including Alternaria, Helminthosporium, Harmondendrum and Spondylocladium; Moniliaceae including Aspergillus and Penicillium; Tuberculariaceae with Fusarium and Sphaeropsidales with Phoma. Many moulds represent asexual (or imperfect) faces of Ascomycetous fungi.

Several allergists have stated that the clinical impression within this group indicates the spores of Alternaria are the most potent aeroallergens.

Lewis et al concluded that of all the eight genera representing a diverse group of common fungal aeroallergens, only Alternaria elicited a distinctly high allergic reaction and frequency in the population sampled. This may be due to the fact that Alternaria may be a common spore indoors. They also supported that other commonly occurring fungal aeroallergens such as Geotrichum, Aureobasidium (Pullularia), Trichoderma and Ustilago (smut) be incorporated into routine regimens so that additional aeroallergens may be recorded for subsequent treatment based on more diagnosis to date. They also pointed out that prick test in paediatric patients responded at a higher level than the adults to all fungal extracts probably due to early exposure of the children to the fungi.

Coping with Asthma

Coping with Asthma

If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.

Get My Free Ebook


Responses

  • Diamond
    What do mean phoma hybernica?
    5 years ago

Post a comment