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 Introduction:
During our work in the Emergency Department,
Hamad General Hospital, Qatar, a considerable
number of patients attended A&E with
acute allergic reactions caused by stings
of black ants from the species Acanthonyps
(lasius) nigar, varying from localized
skin allergic reaction to severe systemic
anaphylaxis.
It has been reported that there are many
species of ants found in the United states,
Australia and Korea that resulted in untoward
reactions to the stings of these insects
(1), there are four species of fife ants
in the United States, the most common
of which is, Solonopsis lnvicta. Reactions
to stings of these species could be life
threatening to some patients who are initially
sensitized to S.lnvicta (2).
Similar reactions has been reported in
southeastemAustralia to ants of the genus
Myrmecia, including Jumper Ant and Bull
ant (3), as well as in South Korea from
the Pachycondyla species
(4).
So far no clinical study has been done
on such a problem in Qatar, where we face
an increasing number of cases of systemic
allergy to black ant stings especially
during our long and hot summer months.
Objectives:
To study the modes of clinical presentation
of black ant sting allergy in Qatar and
compare that with the problem faced in
other countries such as United States
of America, Australia and South Korea.
Materials and Methods:
Charts of patients who attended the
Emergency Department of Hamad General
Hospital with allergic reactions due to
Black Ant stings between 1st of January
to 31st of December, 1998,were reviewed,
and analyzed retrospectively for demographic
data, such as age, sex, nationality, and
modes of clinical presentation, such as
pain, itching, rash, shortness of breath,
wheezes, Systemic anaphylaxis etc.. .besides
other data related to therapy used, and
outcome.
Data are presented in descriptive format.
Results:
Between 1st of January and 31st of December
1998,a total of 105 patients attended
Emergency Department of Hamad General
Hospital suffering from allergic reactions
to Black Ant Stings
Most of the patients suffered the incident
during the summer months, 6 (5.71 %) cases
in June, 57(54%) in July 29(28%) in August
13(12%) in September, but no patients
between January and May (Fig. 1).
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Fig.1
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More than half of the patients 56(53%),
came at night, the rest 49(47%) came during
the day
Mean age of patients was 35.06 (range
13-66), of whom 75(71%) were females,
the rest, 30 (29%) were males.
Regarding past medical history, 44 patients
(42%) had past history of allergy to other
allergens, 45patients (43%) had been exposed
to ant stings before, while 60(57%) patients
had not been exposed, one patient only
(1 % ) had past history of bronchial asthma.
Regarding clinical presentation, most
patients presented with low-grade fever
hyperventilation, and tachycardia. Mean
temperature was 36.79 (Range 35-38.6),
mean respiratory rate was 22.67(Range
10-36), mean pulse rate was94.16 (Range36-
147).
Eighty seven (82.85%) of the patients
presented with itching, 11(10.47%) patients
had localized rash, 26(25%) had generalized
rash, 54(51.4%) had erythematous rash,
and 52(50%) had maculopapular rash
Fifty-seven (54.28%) of patients had shortness
of breath, 38(36%) suffered wheezes, 67(64%)
had no systemic allergic manifestations.
Regarding therapy, 94(90%) patients had
oxygen therapy ,2-4Um by nasal canula
to keep their 02 Sat. by pulse oximetry
over 95%
Those with systemic manifestations and
tachycardia ,36(34%) received intravenous
fluids in the form of Ringers Lactate
500-1000 m1 over 2-4 hours until their
symptoms 1 subsided and their vitals normalized,
103 patients (99%) received Antihistamine
injection to start with, 14 patients (13
% ) needed
1cc (1/1000) Adrenaline s/c injections,
while 37(35%) patients] needed a bronchodilator
in the form of B2 Agonist nebuliser. ]
Regarding outcome: 3 patients (3.15%)
had severe] anaphylaxis, all of them were
females, one patient developed cardiac
arrest on arrival to the hospital, secondary
to severe anaphylaxis, she was resuscitated
using the ACLS protocol ttnd c admitted
to intensive care unit, discharged home
after few days with no residual neurological
deficit. The rest of the patients were
treated in the A&E resuscitation room
and were discharged j home with Epi-Pen
(self-injectable Adrenaline) for those
with recurrent Ant sting allergy and liability
for anaphylaxis.
Discussion:
Ant sting allergy is a well known clinical
problem in the ~ United States and other
parts of the world like Australia and
South Korea due to the variable species
of ants. This clinical " problem has not
been reported or studied before in Qatar
inspite of its frequent occurrence (21cases/lOO,OOO
population/year) , particularly during
the hot summer months as shown in our
study. . Our study matches what was reported
about the Fire Ant stings l in United
States that also occur more commonly during
the summer months (5), this could be explained
by the fact that ants hybernate during
cold winter months.
It has been shown that ant stings could
cause a variety of ~ local and systemic
reactions from mild skin rash to severe
anaphylaxis (6), to death, that can occur
secondary to systemic anaphylaxis (9) which has been shown
to occur in 0.6-6% of 1 persons who
were stung by fire ants (10), similar
results were shown in our study.
It was reported that imported Fire ant
stings in southern United States (7),
causes local signs and symptoms like pain,
warmth, urticaria, etc.and less commonly
systemic reactions, like fever, nausea,
shortness of breath, coughing,
hypotension
etc. (8)
Besides, it has been reported that there
are several species of ants that cause
untoward reactions in Australia, such
as Jumper Ani and Bull Ant from the genus
Myrmecia, and it has been shown that 36%
of the patients had history of more than
one sting and only 30% of the patients
with generalised reaction were treated
with epinephrine (11), similar results
shown in our study
In South Korea, ant from the species Pachycondyla
which belong to the subfamily Ponerinae
which includes about 70 genera and mostly
occur in the tropics and subtropics mainly
causes systemic reaction in the form of
generalised urticaria, conjunctival injection,
angioedema, but the prevalence of anaphylactic
reaction has not been established.
It has been shown that immunotherapy with
Imported Fire ant extract might not benefit
patients with anaphylactic reaction to
Pachycondyla species (4)
Conclusion:
Black ant sting allergy constitutes a considerable clinical problem in Qatar, and warrants further studies on treatment, and prophylaxis, in the sense of developing specific immunotherapy. Meanwhile, patients with recurrent ant stings and liability for anaphylaxis should be educated about anaphylaxis fIrst aid with adrenaline self injectable syringes
until the patient seeks medical advice (12).
References:
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