Nairobi Fly Dermatitis Outbreak Investigation In Bodite Town Administrationwolaita Zone, Southern Ethiopia, April, 2018

Methodology

Nairobi fly (Paederus) dermatitis is a peculiar, irritant contact dermatitis characterized by a sudden onset of erythematobul-lous lesions on exposed areas of the body.Common species of Paederus which have been reported to cause contact dermatitis were P. sabaeus, P. fuscipes, and P. eximius [1]. There are600 species of genus Paederus worldwide. It is an active predator of several crop-damaging insects and occurs in warm tropical cli- mates [2]. In East Africa, outbreaks of Paederus dermatitis and conjunctivitis were mostly reported in Kenya and northern Tan¬zania after the 1997/1998 El NiÅ?o rains [3]. A rapid increase in their population has been attributed to the increased rains asso¬ciated with the el Niño phenomenon [4]. The name ‘Nairobi fly’ is applied to PaederussabaeusErichson and Paederuscrebrepunc-tatus that both cause dermatitis and conjunctivitis in East Africa. Paederus dermatitis has also been reported from Nigeria, France, Okinawa, Australia, Malaysia, Indonesia, Thailand, Singapore, Taiwan, India, Vietnam (Perumbavoor, Kerala), Sierra Leone and Sri Lanka [5-6]. These insects require moist soils for their normal life cycle, so their population increased rapidly during March-April and July-August due to favorable abiotic environ-mental factors [7]. The difference in population during different months was due to biotic factors including different crops and such abiotic factors as temperature, relative humidity and soil moisture contents [8]. It is synthesized in only about 90% of the females the manufacture of pederin is largely confined to adult female beetles—larvae and males only store pederin acquired maternally (i.e., through eggs) or by ingestion [9]. Recently, it has been demonstrated that the production of paederin relies on the activities of an endosymbiont (Pseudomonas bacteria spe¬cies) within the beetle that probably essential for the synthesis of pederin and present only in the (+) females [1]. They can be especially troublesome if windows or doors are left wide open. This beetle does not bite or sting, but accidental brushing against it or crushing it over the skin provokes the release of its coelomic fluid, which contains paederin, a potent vesicant agent that re- sults in itching, burning, erythema and oozing 12-48 hours later [9].

Unusual skin condition was noticed by Boditi health center health professionals and subsequently the situation was official¬ly disclosed by boditi health office to Wolaita zone health de¬partment on 3/8/2018. Zonal health department sent a RRT that included physicians, public health officers and residents field epidemiology to investigate the outbreak, to identify risk factors and propose appropriate control measures.

Methods And Materials

Study Area

The study was conducted at boditi town administration. It is lo¬cated 18 km North to Wolayita zone, Sodo town. Boditi town administration health Office comprises of 1 primary Hospital, 1 Health center (HC), 3Health posts (HP), & 5 private health sec¬tors which were reporting regularly making the potential health coverage of the town administration to be 100 %in the year 2017 [10].

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Study Design

We conducted a descriptive study followed by unmatched case-control.

Study Period

Data were analyzed from the beginning of the outbreak, from April 5 to 14, 2018 G.C.

Data Dissemination

Written report (both hard and soft copies) was prepared and shared toBodit town administration, Wolaita Zonal health de-partment, Hawassa University School of Public Health Resident advisors and coordinators and for South Ethiopia Health Bureau of PHEM.

Sample Size

Unmatched case-control study in the ratio of 1:2 (45 cases-90 controls) was conducted.

Operational Definition

Cases All cases of Nairobi fly dermatitis, in which the diagnosis was established clinically with a detailed history and dermatological examination, characterized as linear dermatitis, kissing/mirror image/ lesions, multiple vesiculo- pustular lesion, extensive pustules ,Blistering and papulo-pustular lesions over face, neck, arms, shoulders, axillaries region, lower limbs, chest, upper limbs or any other area of the body with or without history of contact with insect in patients that live in or have visited boditi health center since April 5-14, 2018.

Controls

Any person in the area without signs or symptom of the disease during the study period

Selection of Cases and Controls

Patients with peculiar skin infections were taken from boditi health center and using house to house visit in the affected Vil¬lage from April 05-14/2018. Necessary information was taken from all eligible cases. Controls were enrolled from the commu- nity in which cases were found. Controls were selected from the same households where cases were resides using lottery method. Where asymptomatic cases were not available, the next house-holds were used to include in the control group.

Inclusion Criteria

1. Cases Any residents of Ade charake village, who had symp-toms of disease and agreed to participate.

2. Controls Any residents of Ade charake village during the study who was a neighbor to a case and who did not develop signs and symptoms of disease and agreed to participate.

Exclusion Criteria

• Cases Those who refused to participate and other differentials of skin disease

• Control Those who refused to participate and did not fulfill inclusion criteria

Environmental Investigation

We assessed the general living environment of cases and con-trols. In addition to this we assessed the possible Nairobi fly breeding sites within the community and nearby rivers, vege-tation or fruits around the home, forest in the surrounding area, grassy land, hygiene and sanitation activities were assessed ac-tively; especially poor housing condition such as broken doors and windows or not using screen in both, living condition in general observed and information obtained on other possible factors.

Data Collection Method

Registration book of the health center was reviewed retrospec¬tively to observe if similar outbreak had occurred and to set background the status of the disease. Active case search was conducted using line listing of cases. Structured Interviewer ad¬ministered questionnaires were used.

Data Analysis

Data generated from the study were entered Epi- info version 7.0 and transferred to SPSS version 25 for analysis proportion, means, tables and graphs used for data summarization and pre¬sentation. Degree of association was measured by odds ratio with 95% confidence interval (CI). Logistic regression analysis was performed to identify the risk factors of the disease by con¬trolling age, Sex and other socioeconomic variables.

Result

Totally 45 cases and no deaths were detected from April 05 to 14/2018 in Ade Charake village of Bodit town administration. The median age of the cases was 28 years old with a range of 1 to 60. Out of 45 total cases 27 (60%) were females and 18 (40%) males. All of the cases did not have travel history and the disease was not reported in that kebele ever before. Both the cases and controls of this study did not know the cause, transmission, pre¬vention and treatment of the disease.

Figure 2: Distribution of Nairobi fly dermatitis suspected cases by date of disease onset in Ade Charakekebele of Bodit administra-tive town, Wolaita zone, South Ethiopia, April 5-14, 2018.

The onset of the outbreak was on April 5/2018. Peak cases were seen in the onset but dropdown diminishingly in similar fashion, until 16/2018. All cases were found in one kebele and had epidemiologically linked.

Figure 3: Distribution of Nairobi fly Cases by age group, Bodit town administration, Wolaita Zone, South Ethiopia, April 5-14, 2018.

The majority of patients were in the age group8-15 years (AR=31%) affected and 0-7 years old were lest (8.8%) affected age group.

Of the 45 patients, 32 patients (71 %) and 28(62%) were symp-tomatic with sensations of burning and itching, the burning sen- sation was more pronounced compared to itching. Clinically most patients had perorbital Conjunctivitis 17(37.7%). Vesicular postular lesions were present in 10 patients (22%). A striking feature was the presence of numerous Erythmato-vesicular le¬sions in 18 patients (40 %). None of the patients had exhibited residual effect of the skin due to the fly.

Table 1: Clinical presentations of Nairobi fly dermatitis, Bodit administrative town, Wolayita Zone, South Ethiopia, April 2018

Regarding the clinical findings of this study, all of the cases were observed on the exposed parts of the body. The majority 23 (51.1%) and 22(48.9%) of the lesion occurred on Neck and the faces respectively. Genitalia were the list exposed site which accounts 1(2.2%) and 3(6.7%) respectively. Number of lesion ranged from 1 to multiple (more than 5). Mostly, a two lesions were found in 17(37.8%) of the cases, followed by one lesion which was 13(28.9%) of the cases, the remaining 3-5 lesions accounted only 15 (33.3%) of the total cases.

Table 2: Distribution of lesions anatomically in cases, Bodit administrative town, Wolaita Zone, South Ethiopia, and April 2018

Mean duration of the symptoms manifestation were 3 to 5 days.

Table 3: Duration of lesion in affected cases by Nairobi fly dermatitis, Bodit town administration, Wolayita Zone, South Ethiopia, April 2018

Analytical Investigation

Multivariate analysis results showed that Proximity of dense vegetations or fruit trees, habit of leaving night lamp on while sleeping had statically significantly associated with contracting Nairobi fly dermatitis. Those individuals whose houses were in habit of leaving night lamp on while sleeping are 8.47 (95% CI 1.033-64.8) times more likely to develop Nairobi fly dermatitis than their counterparts, Proximity of dense vegetations or fruit trees 7 (95% CI 1.143-43.78) times more affected than those did not.

Table 4: Multivariate logistic regression analyses of factors that have been associated with the development of lesions in Bodit town, Wolaita Zone, South Ethiopia, April 2018

Nairobi Fly Dermatitis Outbreak Investigation

Some of the Nairobi fly dermatits cases in Ade charake village in Bodit town administration, Wolaita Zone,SNNPR, Ethiopia, 2018

Discussion

The name ‘Nairobi fly’ is applied to Paederus sabaeus Erich-son and Paederus crebrepunctatus that both cause dermatitis and conjunctivitis in East Africa [3]. Nairobi fly dermatitis may af¬fect people of any sex, age, race or socioeconomic status. The risk depends on the parson’s activities and the insect habitat, exposed skin areas are at higher risk [11]. Nairobi fly dermatitis occurs predominantly on exposed parts of the body. Specially, face and neck were found to be the most commonly involved sites. Our study also found the dermatitis more commonly over uncovered parts of the body; the majority of the lesions were on the neck and face. Facial lesions had predilection for the peror¬bital region in 17(37.8%) percent of patients [12].

The increase in the Paederus sp. population and the increased dermatitis cases have been shown to occur during the rainy season. In similar study, Paederus dermatitis and conjunctivitis occurs mainly during the rainy season (March and October) in the north (Kilimanjaro and Arusha).Maximum cases reported in the month of April [6, 13]. This study suggested that females were more affected than males which are similar with the study done in Gurgaon [14]. However in other studies that were done in Province of Darien, Panama male sexes were more affected than their counterparts [13]. Though all ages, 8-15 years were affected more. This could be due to that older people may be more resistant to the bites than younger children and the young have more outdoor activities which more exposes to the bites of sand flies. Most of the cases had two lesions which are domi-nantly found on neck and face of the cases which is similar with the study that was conducted in panama [14]. Those individu¬als whose houses were in habit of leaving night lamp on while sleeping are 8.47 (95% CI 1.033-64.8) times more likely to de¬velop Nairobi fly dermatitis than their counter parts, Proximity of dense vegetations or fruit trees 7 (95% CI 1.143-43.78) times more affected than those who did not . The same study done on Sierra leone, showed that lamp on while sleeping significantly associated with contracting Nairobi fly dermatitis [12].

Ecological changes and climatic variations, such as El Niño, have also led to the appearance of unusual outbreaks of dermati¬tis caused by some species of these insects, which increase year after year in some regions worldwide [11, 15]. Global warming can also lead to increased incidence of Paederus sp. since high¬er temperatures may influence the ecological dynamics of some insect species. The increases in Paederus sp. populations and the dermatitis case reports in this outbreak could be due to climatic changes related to the onset of the rainy season; unfortunately, due to the limitation of current study, such variables were not available during the outbreak period in order to correlate them with the case incidence [16]. Heavy rainfall and consequently the increase of vegetation in deforested areas and along with the change in temperature and humidity cause an alteration in the natural habitat of these insects [17]. This may leads to the migra¬tion and proliferation of these insects to more urbanized areas, especially where there is artificial light [18-19]. Nairobi fly der¬matitis outbreak was the new event in Bodit town administration and the community did not know the name of the disease, cause, transmission, prevention, control and treatment of the disease, before investigation. Some of them believe that the disease is caused as a result of sin and others thought that the transmis¬sion is due to contact. Due to these perceptions they discriminate cases and the cases affected psychologically. However, the lim¬itation of this study was unavailability of expert dermatologist, laboratory investigation and entomological survey. Recall bias was also one limitation to remember onset of the date.

Conclusion

Nairobi fly dermatitis is an uncommon condition but, can be pre¬vented by increased public awareness. Inhabit of leaving night lamp on while sleeping, the proximity of dense vegetations or fruit trees and disposing wastes near vicinity significantly as¬sociated with Nairobi fly dermatitis. We conducted a series of awareness campaigns in and around the affected kebele stress¬ing on the simple preventive measures based on the behavioral pattern of this nocturnal beetle, leading to a significant reduction in the incidence of disease. Health professionals in the affected areas should also be enlightened of this condition and its man¬agement. Awareness about the morphological patterns of the condition and its clinical features will prevent misdiagnosis.

List of Abbreviations

AOR: Adjusted Odds Ratio, AR: Attack rate, C I: Confidence In¬terval, COR: Crude Odds Ratio, HC: Health Center, HP: Health Post, PHEM: Public Health Emergency Management, RRT: Rapid Response Team, SPSS: Software Package Social Scienc¬es.

Acknowledgement

I would like to take this opportunity to express my heartfelt thanks and appreciation to my advisor Dr. Mesay Hailu for his constructive comment, unreserved advice and made continuous follow up to complete on each of the outputs undertaken. Once again, I gratefully acknowledge Zonal Health department staff for their kindly support in general; and Mr. Ambesaw Wolde (Zonal Health department Head for his motivation toward ac¬complishing residents their field work in timely manner; the PHEM coordinator (Mr.Temese Teka) facilitating in the entire field activities and program management.

Funding

The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. The authors and their contributions to the manuscript are independent from the funder.

Availability of Data and Materials

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Ethics Approval and Consent to Participate

All participants were informed about the objective of the study, confidentiality of the participants were assured and informed consent was sought from and given by the participants, with the knowledge they were free to withdraw at any time. Ethical clear¬ance was obtained from the institutional review board of Hawas¬sa University, College of health sciences and the support letter was written from Wolayita Zone health department to Boditi town administration.

Competing Interests

The authors declared that there is no competing interest.

Consent for Publication Springer

Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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