Acute haemorrhagic conjunctivitis epidemics and outbreaks of Paederus spp. keratoconjunctivitis (‘Nairobi red eyes’) and dermatitis
An epidemic of acute conjunctivitis in Dar es Salaam in 2010 demonstrated the importance of a strong infectious diseases epidemiological surveillance network to minimise disease outbreaks.
Misunderstanding of the causes and management of diseases explains the
repetitive nature of acute haemorrhagic conjunctivitis (AHC) in Dar es
Salaam. This paper discusses AHC and Paederus spp.
keratoconjunctivitis and periorbital oedema (‘Nairobi red eyes’) that
are confused as being associated with recurrent epidemics of
conjunctivitis in Dar es Salaam.
S Afr Med J 2011;101:541-543.
Many cases of conjunctivitis were reported in mid-2010 in Dar es Salaam,1
of a kind that has been reported in the region since the 1980s.
Conjunctivitis is generally caused by an allergic reaction or infection
(usually viral but sometimes bacterial).2
The causes have been confused by health care personnel in developed and
developing countries. Conjunctivitis epidemics in Tanzania, regardless
of their causes, are called ‘Nairobi red eyes’ or
‘Nairobi eyes’. The resulting labelling of all
conjunctivitis epidemics in Dar es Salaam as ‘Nairobi red
eyes’ is incorrect because Nairobi red eyes or Paederus spp. (Nairobi fly, Rove beetle) keratoconjuctivitis occurs very rarely.3,8,20
Conjunctivitis epidemics in Dar es Salaam
have been due to enteroviruses 70 (EV-70), coxsackie virus A24,
adenoviruses and gonococcal ophthalmia,4
which cause photophobia, watering, foreign body sensation, eyelid
oedema, conjunctival haemorrhages and superficial punctuate keratitis
(acute haemorrhagic conjunctivitis).5 They are not associated with Rove beetle/Nairobi fly.3,8,20
Paederus conjunctivitis (‘Nairobi eyes’) and dermatitis outbreaks
Paederus dermatitis and conjunctivitis
outbreaks have been reported since the earliest recorded times. The
third and fourth plagues in Exodus in the Old Testament are believed to
have been due to Paederus arfieri.6 In Africa, Paederus dermatitis was first reported in 19157 and documented in East Africa (then British East Africa) in 1916.8 The effects of Paederus species have been reported in Leopoldville (Kinshasa) in 1921),9 in Freetown in 1925,10 India in 1933,11 Sudan in 1958,12 and in Nyasaland (now Malawi) and Tsumeb (Namibia) in 1962.13 More recently, Paederus conjunctivitis and dermatitis have been reported in India,14 China,15 Iran,16 Nigeria,17 Sri Lanka18 and Guinea.19
In Tanzania, Paederus dermatitis and conjunctivitis occurs mainly during the rainy season (March and October) in the north (Kilimanjaro and Arusha),20 with no cases in the coastal region, so excluding Paederus (Nairobi fly) as a cause of conjunctivitis in Dar es Salaam, as reported by many.
Conjunctivitis from Paederus is rare. The beetle affects mostly the skin after contact with the body and releasing pederin toxins.20 Conjunctivitis results from transferring toxins by finger to the eyes (Nairobi eyes).16-20 The rapid spread and mechanism of transmission of conjunctivitis reported in Dar es Salaam are unlike that of Paederus conjunctivitis, which is slow and occurs rarely.
Rove beetles (Paederus spp.)
Several species of Paederus cause ‘Nairobi red eyes’. The genus Paederus is widely distributed worldwide and belongs to the family Staphylinidae of the order Coleoptera.21 Of the approximately
3 000 species of Staphylinidae, 600 occur in tropical and temperate
climates. In the order Coleoptera, only Meloidae, Oedemeridae and
Staphylinidae release vesicant chemicals that cause dermatitis and
conjunctivitis (the first two release cantharidin and the latter,
pederin).14 The genus Paederus comprises more than 622 species.21,22
The name ‘Nairobi fly’ is applied to Paederus sabaeus Erichson and Paederus crebrepunctatus that both cause dermatitis and conjunctivitis in East Africa.20,23
They are morphologically similar, with a narrow body, black head, at
least two abdominal segments, and the prothorax and the first 5
abdominal segments are russet coloured14
(Fig. 1). They range in length from 10 - 15 mm, can fly but prefer to
run, neither bite nor sting, cause irritation and blistering if crushed
against the skin or eye, and are attracted to artificial light sources.16-24
breeds in wet, rotting leaves and soil. Their population increases
rapidly in the rainy season and diminishes in the dry season. In East
Africa, outbreaks of Paederus dermatitis and conjunctivitis were mostly reported in Kenya and northern Tanzania after the 1997/1998 El Niňo rains.20,25
dermatitis is caused by accidentally crushing the insect against the
skin, so releasing coeleomic fluid that contains pederin, a potent
vesicant. This causes an acute irritant-contact dermatitis within 24
hours, which may be associated with bullae or pustulae. ‘Kissing
lesions’ can occur after spreading of pederin to adjacent skin
surfaces, usually flexural e.g. the elbow. Skin lesions heal after 10 -
12 days, with transient post-inflammatory hyperpigmentation; they may
be confused with allergic or irritant-contact dermatitis, thermal
burns, herpes zoster, dermatitis artefacta, herpes simplex, bullous
impetigo and phytophotodermatitis.16-24
Ocular involvement is usually secondary to
rubbing the eyes with hands contaminated with vesicant fluid. Oedema,
conjunctivitis and excess lacrimation are common and termed
‘Nairobi eyes’.20 The effect of toxins is usually limited to the conjunctiva, and corneal scarring and iritis are rare.20,24 Bilateral Paederus
conjunctivitis is uncommon, providing further proof that ‘Nairobi
fly’ is not responsible for epidemics in Dar es Salaam, where
most cases were of bilateral conjunctivitis.
In East Africa, local remedies (e.g. toothpaste and mud) are used to treat Paederus dermatitis, though all are ineffective.20
The use of cold compressed magnesium sulphate is replacing older
remedies. Cases are managed as irritant dermatitis: removal of
irritant, initial washing with soap and water, and application of cold
wet compresses followed by steroid and antibiotics, if there is a
beetles can be prevented by increasing public awareness and applying
methods used in the prevention of other insect-borne diseases
(insect-proof mesh, insecticides etc.)20,21,24
Acute haemorrhagic conjunctivitis (AHC) epidemics
The magnitude of an epidemic of conjunctivitis
in 2010 in Tanzania can be directly linked to enterovirus 70 and
coxsackievirus A24. Numerous epidemics have been documented worldwide,
and the clinical and epidemiological features of conjunctivitis in Dar
es Salaam are similar to those in other countries. Outbreaks of
conjunctivitis in Dar es Salaam move rapidly, and are associated with
AHC rather than Paederus spp. conjunctivitis (‘Nairobi red eyes’). A few cases of gonococcal ophthalmia were reported 1984,4
but increasing numbers of cases have since been reported in Dar es
Salaam and neighbouring regions, affecting people living in densely
populated areas such as slums.4 The epidemiology and disease trend prove that the infections are likely to be viral or bacterial, and not Nairobi red eye.
Viral conjunctivitis, with bilateral
involvement with symptoms such as hyperaemia, congestion, haemorrhage,
follicles, corneal involvement and lymphadenopathy, was first reported
The first outbreak of AHC caused by enterovirus 70 was in Ghana in 1969
(named ‘Apollo’ as it coincided with the Apollo XI moon
From 1969 to 1972, the pandemic disease spread from Ghana across
tropical and subtropical Western and Central Africa to the Middle East
and other parts of Asia, and remains common today.28
In the Western world, the disease was reported in 1981 when the
pandemic (originating from Kenya in 1980) reached South America,
Central America, the Caribbean islands and the USA.29,30
Owing to limited investigative facilities, the agent causing epidemics
of conjunctivitis in Dar es Salaam since the early 1980s had not been
determined. A coxsackievirus A24 causing AHC was first isolated in
Singapore in 1970,31 and outbreaks were then reported in America and in the Caribbean after 15 years of being dormant in south-east Asia.
The genus enterovirus belongs to the family picornaviridae comprising 66 human serotypes that are classified into 5 groups: (i) poliovirus serotypes 1 - 3; (ii) human enterovirus A (HEV-A), including 11 serotypes of coxsackievirus A and EV 71; (iii) human enterovirus B (HEV-B) with 38 serotypes including all coxsackievirus B, all echoviruses, EV69, EV73, and CA9; (iv) human enterovirus C (HEV-C), including 11 serotypes of coxsackievirus A; and (v) human enterovirus D (HEV-D) with only 2 serotypes – EV68 and EV70. Coxsackievirus A24 belongs to HEV-C.29 This genus, together with adenovirus, is associated with epidemics of conjunctivitis all over the world.
Enterovirus infections have many clinical
outcomes e.g. poliomyelitis, aseptic meningitis, hand-foot-mouth
disease, herpangina and acute haemorrhagic conjunctivitis. Many
epidemics of AHC are linked with influenza pandemics and other
enterovirus serotypes e.g. poliovirus type 1 (wild).32
AHC occurs mostly in tropical coastal areas during and after rainy
seasons (in some parts of the world, AHC epidemics occur during dry,
dusty, windy seasons). Large epidemics of AHC are limited to the
eastern hemisphere and Africa, where overcrowding and unhygienic living
conditions contribute to its spread.30-32
The disease affects all age groups, is
self-limiting and is characterised by abrupt onset of ocular pain,
eyelid oedema, foreign body sensation, rash, redness of eyes with
subconjunctival haemorrhages and epiphora (Fig. 2).33
Initially unilateral, it becomes bilateral within 24 hours and may
persist for 3 - 7 days before spontaneous resolution. Mismanagement
(including self-medication and consulting traditional healers) can
result in corneal perforation, panophthalmitis and blindness.30-33 In Asia, rare cases of polio-like paralysis have been linked to enterovirus 70 and coxsackievirus A24.32
In settings with limited resources, AHC can
be diagnosed clinically or by excluding common bacterial infections
(bacterial cultures: absence of bacterial growth prepared from the
conjunctival swabs of patients, denotes viral or fungal infections),
but tissue cultures and virus isolation, nucleic acid detection methods
and serology testing are recommended.34
AHC epidemics can be prevented by personal
hygiene, discouraging the sharing of towels and toiletries etc.,
frequent hand washing, and elimination of crowded living conditions.32,34
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Accepted 9 November 2010.