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Latex allergy and its clinical features among healthcare workers at Mankweng Hospital, Limpopo Province, South Africa
1 Department of Pulmonology and Allergy, Polokwane/Mankweng Complex and University of Limpopo, Limpopo, South Africa
2 Department of Public Health Medicine, Polokwane/Mankweng Complex and University of Limpopo, Limpopo, South Africa
3
Department
of Paediatrics and Child Health, University of Pretoria and
Steve Biko Academic Hospital, Pretoria, South Africa
Background and objectives. Latex allergy, caused by sensitisation in atopic individuals, is a common occupational disease among healthcare workers who use latex gloves. It may be present in non-atopic individuals as well. The main objective of this study was to document the prevalence and disease spectrum of latex allergy at Mankweng Hospital, Limpopo Province, South Africa. The secondary objective was to determine clinical presentation of the disease.
Methods. A cross-sectional descriptive study, with an analytical component, was conducted among healthcare workers who worked in high-risk areas for latex sensitisation. ImmunoCAP testing was performed and followed by a skin-prick test (SPT) in those who tested negative to the blood test.
Results. Two hundred screening questionnaires were distributed to healthcare workers at the hospital. Of these 158 (79.0%) were returned, with 59 participants meeting the inclusion criteria (experiencing symptoms due to wearing latex gloves). The mean age of the participants was 39.6 years (standard deviation 9.8 years, range 20 - 60 years). There were more females (98.1%) than males (1.9%). Glove-related symptoms were present in 59 subjects (37.1%), in 7 (11.9%) of whom the ImmunoCAP was positive to latex (95% confidence interval 4.2 - 22.9%). Fourteen participants were lost to follow-up before the SPT was performed. Thirty-eight of the participants with negative ImmunoCAP tests underwent SPT. Positive SPTs were reported in 5 of these 38 workers (13.2%), indicating that the ImmunoCAP test missed 11.1% (5/45) of latex-allergic individuals. The prevalence of latex allergy in this study was 8.3% (12/144). A denominator of 144 was used, as there is a possibility that some of the 14 individuals lost to follow-up could have tested positive to latex sensitisation by SPT. The symptoms experienced by latex-sensitised workers were rhinitis (100.0%), asthma (50.0%), dermatitis (25.0%), severe anaphylaxis (8.3%), abdominal pain (8.3%) and angio-oedema (8.3%).
Conclusion. Our findings reveal that
latex allergy is a problem at our hospital. The prevalence of
8.3% is comparable to findings in other South African centres.
We recommend a latex-free protocol for high-risk areas and
healthcare workers.
S Afr Med J 2013;103(6):390-394.
DOI:10.7196/SAMJ.6011
Gloves made from natural rubber latex (NRL) have been in use since the 19th century as a means of protecting patients and healthcare workers from contracting infectious diseases.1 The use of NRL gloves has increased because of the emergence of the human immunodeficiency virus (HIV) in the late 1980s.1 These NRL gloves were produced with an excess of residual proteins and powder.1
Healthcare workers (HCWs) are susceptible to sensitisation and subsequent development of latex allergy because of frequent exposure to NRL gloves and powder.2 In addition, the prevalence in certain groups, such as people who underwent multiple operations involving exposure to NRL-containing materials at an early age, and those with spina bifida, urological abnormalities and short-bowel syndrome, has been reported to be up to 60% in earlier studies.3 However, this high prevalence is falling as a result of a reduction in exposure to latex.3
Latex allergy is more prevalnet in atopic than non-atopic individuals.3 There is also cross-reactivity with certain foods, including kiwi fruit, bananas, avocados and chestnuts.3 Such cross-reactivity may occur in more than 50% of latex-allergic individuals, and is due to specific cross-reacting allergens such as profilins.4 Notably, about 50% of medical devices contain latex, so care has to be taken to identify them and avoid contact by latex-sensitised and allergic individuals.1
In highly industrialised countries such as those of Europe and North America, the latex epidemic in HCWs has been partly halted by prevention strategies such as lowering the protein content in gloves5 recommended by task forces of the European and American allergy associations.5 New cases of NRL allergy have been significantly reduced, and in certain circumstances have disappeared, in countries and hospitals where health authorities have enforced the use of low-allergen/low-protein and non-powdered protective gloves.3
The first cases of latex allergy (type I hypersensitivity) were described in 1927 in Germany.5 The first case in South Africa (SA) was diagnosed in 1993 at Groote Schuur Hospital in Cape Town, in a nursing sister.6
Reactions to NRL gloves can present in three ways:
1. Contact dermatitis on the hands after wearing gloves resulting from mechanical friction and drying due to dry powder particles. This is not an immune-mediated reaction and accounts for the majority of latex-induced skin rashes.
2. Allergic contact dermatitis is a type IV delayed hypersensitivity reaction usually caused by the chemical accelerators (such as carbamates, thiurams and benzothiazoles) used in the manufacture of NRL gloves. This is a cell-mediated immune response that develops 24 - 48 hours after exposure to latex.
3. The type 1 immediate hypersensitivity reaction to latex, an IgE-mediated hypersensitivity reaction to latex protein, can result from contact with latex allergens through the skin or mucous membranes. It has not been documented that the powder used in latex gloves is allergenic, but it may carry latex proteins that can lead to an allergic reaction on coming into contact with mucous membranes. Symptoms usually begin within minutes of exposure. This is the most serious type of latex allergy and may be fatal.
This study’s main objective was to determine the
prevalence of latex allergy at Mankweng Hospital, a 500-bed
rural tertiary teaching hospital of the University of Limpopo,
Polokwane Campus, Limpopo Province, South Africa. The
secondary objective was to determine the disease spectrum of
affected staff members exposed to latex gloves.
Material and methods
Study population
A cross-sectional descriptive study was conducted among HCWs (nurses, medical doctors and cleaners) working in high-risk areas of Mankweng Hospital. The great majority of HCWs at highest risk of latex sensitisation are nurses. Ethics clearance was obtained from the Ethics Committee of the University of Limpopo, Polokwane Campus. The participants signed forms indicating their informed consent to participate in the study.
Participants were recruited during March - December 2011 from
the intensive care unit, labour ward, gynaecology and postnatal
ward, casualty, outpatient department, neonatal intensive care
unit, antenatal clinic, operating theatre, central sterilising
department, radiology, high care, and the Thuthuzela Rape
Clinic. The hospital has a nursing staff complement of
704 and has a policy of keeping nurses in their preferred
workstations permanently. All participants had been in their
workstation for a year or more. The number of nurses in
different stations is shown in Table 1.
Sample size
We assumed the prevalence of type 1 latex allergy in the study
population to be about 10%, with a margin of error of 4%. In
order to be 95% confident we needed to have a total of 200 HCWs
in high-risk areas using simple random sampling.
Development and logistics
We conducted a small-scale pilot study of 10 participants in
January 2011 to test our questionnaire. We then started our
study by having a discussion on latex allergy in every
workstation in order to explain the study and answer questions.
Questionnaires and information on latex allergy were given to
HCWs who wanted to participate in the study. We collected blood
from participants who met the inclusion criteria and later did
skin-prick tests (SPTs) in those whose blood tests were
negative.
Questionnaire
A self-administered questionnaire was designed to elicit any allergic symptoms, collecting the following information: (i) demographic data; (ii) symptoms; (iii) family history; (iv) food allergy (avocados, bananas, carrots, pineapples and watermelons); (v) previous allergy evaluation and therapy; (vi) hospitalisation; and (vii) surgery. The questionnaire was in English, the official language used to record patient information at the hospital. HCWs in different workstations were addressed to explain the study, and questions asked were clarified. They were addressed in English, Sepedi, Tshivenda and Xitsonga, the four common languages spoken at the hospital. For the few participants who could not understand English well, the information was interpreted in their home language by the investigators, who can speak all three African languages. There is evidence that a questionnaire addressing past symptoms of latex allergy can be useful in screening for latex allergy.7 Questionnaires are particularly useful in the identification of sensitised and asymptomatic patients belonging to high-risk groups and in prevalence studies.5
Participants were required to score their symptoms after exposure to latex as absent, mild, moderate or severe and to state whether they were work-related or not. Symptoms were graded as severe if the participant had needed medical attention or admission to hospital.
Inclusion criteria for further study (latex sensitisation and
allergy testing) were: (i)
confirmed or suspected latex allergy; (ii)
severe reaction after exposure to latex; (iii)
allergy to food that cross-reacts with latex; (iv) any other symptom with work-related
deterioration; (v) 1 or more severe
symptoms listed in the questionnaire; (vi)
2 or more moderate symptoms in the questionnaire; and (vii) 4 or more mild symptoms in the
questionnaire. Fifty-nine participants met these inclusion
criteria for latex sensitisation and allergy testing.
Specific IgE measurements
The k82 Latex ImmunoCAP system (Phadia, Uppsala, Sweden) was
used to determine serum-specific IgE to latex antigens. The
latex allergen components documented on this system are Hev b 1,
Hev b 2, Hev b 3, Hev b 5 Hev b 6.01, Hev b 6.02, Hev b 7.01,
Hev b 7.02 Hev b 8, Hev b 9, Hev b 10 and Hev b 11. The first 7
latex allergens listed above are of medium to high significance,
with Hev b 7.01 through Hev b 11 having low significance in HCWs
and children with spina bifida.8 There is cross-reactivity,
especially to bananas, avocados and kiwi fruit, with Hev b 6.01
through Hev b 6.03. Hev b 8 to Hev b 11 reveal low
cross-reactivity with some fruit and mould allergens.8 A value
of >0.35 kU/l was considered positive. Clotted blood was
collected and sent to Lancet Laboratory, Polokwane, for testing.
Skin-prick tests
SPTs were performed on subjects who tested negative to blood
tests. We used standardised 1 mm-tipped lancets (ALK-Abello,
Madrid, Spain) and latex extracts (500 µg/ml protein
concentrate). Histamine (10 mg/ml) was used as a positive
control and normal saline as a negative control (ALK-Abello). A
drop of the extract was placed on the volar area of the forearm
and introduced into the epidermis through lancet puncture. The
result was examined after 15 minutes and the average diameter of
the wheal measured. A positive result was interpreted as an
average diameter of ≥3 mm compared with the negative control.
Results
A total of 158 HCWs (all nurses) returned the questionnaires
and therefore participated in the baseline study, giving a
participation rate of 79.5% (158/200). Doctors and cleaners did
not return the questionnaires, perhaps because they did not
regard themselves as being at risk for latex allergy.
Demographic characteristics of the study participants are
presented in Table 2.
The mean age of the study participants was 39.6 years (standard deviation (SD) 9.8 years, range 20 - 60 years). There were more females (98.1%) than males. Fourteen participants did not continue with the study due to: death (2), proving untraceable (4), and refusal to continue for personal reasons (8). Glove-related symptoms were present in 59 HCWs (37.1%), of whom 7 (11.9%) had positive SPTs to latex (95% confidence interval 4.2 - 22.9%). Latex (K82) titres of the participants who tested positive were, in ascending order, 0.87 kU/l, 1.16 kU/l, 2.51 kU/l, 3.61 kU/l, 7.74 kU/l, 14.5 kU/l, and 45 kU/l. Thirty-eight participants with negative blood tests underwent SPTs, 5 of which were positive, with readings of 3 mm, 3 mm, 4 mm, 4 mm and 7 mm.
Positive SPTs were reported in 5 out of 38 workers with negative blood tests (13.2%), indicating that blood tests missed 11.1% of latex-allergic individuals (5/45). The prevalence of latex allergy among HCWs was 8.3% (12/144), after adjusting for the 14 subjects lost to follow-up before SPT. The symptoms experienced were rhinitis in 12 (100.0%), asthma in 6 (50.0%), dermatitis in 3 (25.0%), anaphylaxis requiring mechanical ventilation for 2 weeks in 1 (8.3%), urticaria in 1 (8.3%), abdominal pain in 1 (8.3%) and angio-oedema in 1 (8.3%).
The number of latex-sensitised or allergic individual HCWs per
workstation was also determined (Table 3). The proportion was
highest among labour ward staff.
Clinical symptoms in participants who met inclusion criteria for sensitisation testing
The clinical symptoms of the participants are listed in Table
4. Of note is that 54 participants had more than one symptom.
Among those who were positive to either the ImmunoCAP test or
the SPT, symptoms were as follows: 5 had 1 symptom, 4 had 2
symptoms and the other 3 had 3 or more symptoms. All the
participants who tested positive had rhinitis, and half had
asthma. There was no statistically significant difference
between the sensitised (latex-positive) and non-sensitised
(latex-negative) groups with regard to rhinitis, asthma,
anaphylaxis requiring ventilation, abdominal pain, urticaria and
angio-oedema (p>0.05). A
statistically significant association was observed with regard
to dermatitis in terms of latex exposure in the two groups (p<0.05).
Discussion
The participation rate was adequate, with 79% answering the questionnaires. The sample was not obtained by random selection, however, but depended on participants returning questionnaires. As a result, generalisability to the hospital may not be possible.
Among the 59 participants who met the inclusion criteria (symptoms due to using latex gloves), 12/45 (26.7%) tested positive for latex sensitisation by ImmunoCAP or SPT. The findings are comparable to those of studies conducted at Dr George Mukhari Hospital (Pretoria) (22%)9 and Groote Schuur Hospital (Cape Town) (25.3%).6
Our latex allergy prevalence of 8.3% is higher than the 4.2% at the Dr George Mukhari Hospital, which is our sister hospital.9 This difference can partly be explained by the fact that in the latter study only the ImmunoCAP test was performed, with no SPT follow-up. We calculated our prevalence with only the ImmunoCAP without an SPT result in the participants with negative blood tests and found a prevalence of 4.9% (7/144), similar to that of the Dr George Mukhari study.
The prevalence of latex allergy at other SA teaching hospitals and institutions has been reported as: Groote Schuur Hospital (Cape Town) 9.2%, Red Cross War Memorial Children’s Hospital (Cape Town) 5%, Tygerberg Hospital (Parow, Cape Town) 20.8% and the South African Institute of Medical Research, now the National Health Laboratory Service (Johannesburg), 10.5%.10 Our prevalence of 8.3% is comparable to most of these, with only Tygerberg Hospital demonstrating a higher prevalence of 20.8%. The actual prevalence of latex sensitisation may be higher than these figures suggest, because some studies show that 25% of SPT-positive patients may be asymptomatic.10
Rates of latex sensitisation and allergic reactions have increased in HCWs exposed to NRL since the 1980s, with prevalences of 6.9 - 17% reported.11 , 12 A study on primary prevention of NRL allergy in Germany by Allmers et al. has confirmed a positive correlation between the use of powdered NRL gloves and suspected occupational latex allergy.13 There is recent evidence that rates of NRL allergy have fallen significantly as a result of latex-free environment strategies and use of low-allergen, powder-free gloves in some industrialised countries.3 Termination of exposure to NRL products is an accepted means of secondary prevention in latex-sensitised individuals.13
The commonest presenting symptoms in both latex-positive and -negative participants who met the inclusion criteria were nasal (100.0% and 74.5%, respectively), followed by asthma in latex-positive (50.0%) and contact dermatitis in latex-negative subjects (46.8%). Other symptom profiles did not reveal any significant differences between latex-positive and -negative participants. There was no statistically significant difference in symptoms between the latex-sensitised and non-sensitised participants, except in those who presented with dermatitis. This can be explained by the fact that the k82 ImmunoCAP does not test some Hev b allergens such as Hev b 6.03, Hev b 12 and Hev b 13.7 SPTs may be negative even in people who are sensitised or allergic to latex, as sensitivity has been shown to be 93 - 96%.14
Shortcomings of the study
Greater participation, especially by doctors, would have
improved the power and generalisability of the study. Several
participants only had blood testing performed without follow-up
SPTs, which could have influenced the prevalence, as some might
have tested positive by SPT.
Recommendations
NRL allergy has been shown to be an important cause of occupational disease. It is important to increase awareness of the sensitising and disease-causing effect of latex gloves in HCWs. Powdered gloves may cause serious latex allergy problems because the latex proteins adhere to the powder, become airborne and are subsequently inhaled.13 This can cause sensitisation in atopic individuals.
Powdered latex gloves can be a hazard not only to the wearer but also to other people in the workstation. The importance of creating latex-free workplaces cannot be over-emphasised, as evidenced by one of our participants who developed anaphylaxis requiring mechanical ventilation. In an ideal situation latex-free gloves should be used, especially in high-exposure areas. This is not feasible in most settings, however, because of the high cost of these gloves.15 It is therefore recommended that powder-free, low-allergen gloves be used as a preventive measure because of their ability to decrease sensitisation.10 Individuals who are sensitised to latex should avoid direct contact with latex gloves but can work at the station with other workers provided the latter are using powder-free gloves.
Once an individual is sensitised it is difficult to
prevent the emergence of symptoms, especially systemic
reactions on contact with latex.13
Everyone with proven latex allergy should wear a Medic Alert
bracelet or band to help HCWs avoid using latex-containing
products such as urinary catheters, endotracheal tubes, oxygen
facemasks and laryngeal airways when caring for them.
Conclusion
The prevalence of latex allergy in HCWs at Mankweng Hospital is
significant, and represents a serious occupational disease. It
is important to strive for a latex-free working environment for
HCWs, especially atopic workers. Risk risk of latex allergy
could be minimised by decreasing extractable proteins in latex
products. This may reduce the risk of litigation against the
hospital and Department of Health.
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Accepted 18
February 2013.
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