The use of chloroquine with or without adjuncts in the effective management of scorpion sting in the tropics: case reports

Introduction and importance:

Scorpion Sting is a common occurrence in the tropics caused by scorpion envenomation on unsuspecting victims. The sting causes severe pain and may be much more fatal depending on the age and size of the patient and the scorpion specie as well as other factors. Effective treatment is needed specially to alleviate pain. Many parts of the tropics have little or no data describing the use of Chloroquine in managing scorpion sting. These cases show how chloroquine can be used in without other drugs to achieve pain control.

Case presentation:

Patients presented with pain emanating from the right big toe and medial arch, respectively. The said pain had same manifestation and intensity in both patients and followed same course but radiated higher in up to the ipsilateral flank in the first patient but was limited to the ipsilateral iliac region of the second patient.

Clinical discussion:

The sites showed signs of inflammation with pain being most prominent. Diagnosis of scorpion envenomation were made based on the given history. The pain was eliminated using chloroquine given intramuscularly at the site of scorpion sting.

Conclusion:

Scorpion sting can occur at any time in the tropic and lidocaine only cannot alleviate pain. Chloroquine can be used in managing scorpion sting as it also has many other benefits that can make it more preferred to the other conventional approaches used.

Introduction

Highlights

• Scorpion Sting is common in the tropics.

• Scorpion sting causes excruciating pain to unsuspecting victims.

• Little or no data describing the use of chloroquine in managing scorpion sting is available in many parts of the tropics.

• Chloroquine is effective in the management of scorpion stings in either alone or in combination with other drugs.

Scorpion stings are common emergency events in many parts of the world vis-à-vis a common health problem in certain areas of the world including Central and South America, North Africa, South Asia, Middle East, Africa and India. About 1.5 million stings have resulted to about 2600 deaths as estimated by the national health data1–3.

Most scorpions found in the tropics are harmless to humans, and even though they can reasonably cause a painful sting, no other lethal effects are anticipated to develop. However, a small number of scorpion species can cause life-threatening systemic envenomation. Children are the most vulnerable, with a mortality rate reaching up to 20%. Some scorpions are of medical importance because of the effect of their sting. They vary in size (1.5–20 cm) and have a sharp, curved needle-like stinger at the end of their jointed tail. Many species possess poisonous glands that produce painful stings in humans. Scorpion stings in humans are mostly accidental and have been noted to be a form of either self-defence or offence mechanism by the scorpion as they are shy creatures. The pain felt is due to the ability of the somatosensory system of the body to detect noxious and potentially tissue damaging stimuli4–7.

So many treatment modalities have been proposed based on the clinical grade of the scorpion sting. However, there is dearth of data regarding the use of chloroquine in the effective management of scorpion stings in the tropics. In Ghana many peripheral hospitals are familiar with the use of injection chloroquine in the management of pain in patients with scorpion stings4, but that is not the case in Nigeria although a report has shown where it was used as an adjunct to lidocaine in achieving pain control6. Our aim is to report the successful use of injection chloroquine with and without adjuncts in the effective management of pain in scorpion stings.

Methods

This case report has been reported in line with the SCARE Criteria8.

Case 1 (Chloroquine with adjunct)

U.I., a 22-year-old male presented with a 1-h history of scorpion sting affecting the right big toe. The pain was sudden in onset, throbbing in character and radiated upward to the ipsilateral flank. There was no sign of systemic involvement. The pain was continuous and increased in intensity from the point of impact to the point of presentation. The patient had no relevant medical or surgical history. Pain score using the Visual Analog Scale was 10 (worst imaginable pain). On examination, the foot showed obvious signs of inflammation. Patient had taken 200 mg Diclofenac and a 3 g bulb of onion before the presentation. On presentation treatment was commenced with a digital block of the affected toe, using 5 ml of lidocaine and adrenaline. This resulted in instant pain relief. Twelve hours later, the pain recurred with the same intensity as at the initial presentation. Digital block was repeated and hydrocortisone 100 mg was given intravenously followed by 5 ml chloroquine hydrochloride injected around the sting site. Pain relief was reported 5 min later and was sustained for 24 h. Later the next day on examination, signs of inflammation had resolved and no more pain was felt.

Case 2 (Chloroquine without adjunct)

I.S., a 24-year-old male presented with a 2-h history of scorpion sting affecting the medial arch of the right foot. The pain was sudden in onset, sharp in character and radiated upward to the ipsilateral iliac region. There was associated headache, sweating, palpitation, hyperpyrexia and inability to walk. The pain was continuous and increased in intensity which spanned to about 30 min to 1 h. The patient had no relevant medical or surgical history. Pain score using the Visual Analog Scale was 10 (worst imaginable pain). On examination, there were obvious signs of inflammation. Patient had received over-the-counter pain relief before the presentation but had no relief. On presentation treatment was commenced with local infiltration of the sting site with 6 ml Chloroquine phosphate. Pain relief was reported 3 min later and was sustained for 24 h. Later the next day on examination, signs of inflammation had resolved and no more pain was felt.

Discussion

In the tropics, scorpion stings barely result in fatal effects except in children7 and when the rare poisonous ones sting. The stings normally occur on the hands and feet and usually come with severe pain that victims normally describe as the worst pain of their life. Severity of sting differs with the scorpion species, size and age, and the age and size of the victim, and site of sting on the victim.

In the case of an envenomation, local infiltration or a ring block with local anaesthetic agents like lidocaine are used to achieve pain relief5, although other principles of management have been outlined which include patient observation and tackling systemic features if present. Other pharmacological approaches have been used but with little or no success or with increased adverse effects such as necrosis6,9–11.

Chloroquine has been mostly used to treat protozoan infections such as malaria, babesiosis, chlornochiasis and more. It is majorly administered orally via tablets and intramuscularly and has been shown to have anti-inflammatory and antihistaminic properties12. Its use as a local anaesthetic is not widely known for its mechanism of action has not been quite understood. However, it is believed to cause changes on synaptic nerve endings by reducing the small contents of the endplate potentials13 and hence reducing the response to nerve stimulation via its inhibitory actions14.

Chloroquine is quite affordable while being readily available as well. It has equal action time with lidocaine and gives a sustained anaesthesia that does not require adrenaline to prolong its duration of action compared to lidocaine; hence no fear of necrosis of terminal arteries. Its indication in treating malaria makes chloroquine a good prophylaxis for malaria when used in scorpion sting victims especially in the tropics; however, care should be taken to prevent resistance against the drug. Also, using chloroquine with adjuncts reduces the chances of adverse effects and may produce additive or synergistic effects. There is also a possibility of chloroquine having antitoxic properties. However, care should be taken while administering the drug due to possibilities of side effects such as blurred vision, pruritus, insomnia and paraesthesia which rarely at the usual doses15–18.

Finally, these cases have further affirmed the use of chloroquine in the effective management of scorpion sting especially with no severe systemic involvement be it in combination of adjuncts or as a monotherapy. However, more studies need to be carried to have more information on the use of chloroquine as an anaesthetic which can be employed even in dental procedures where local anaesthesia is needed.

Ethical approval

NA.

Consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Source of funding

None declared.

Author contributions

O.P.U.: study conceptualization, data collection and writing the paper; O.W.O.: data collection and writing the paper; U.P.: data collection and writing the paper; U.C.: writing the paper; I.D.A.: writing the paper; G.I.D.: writing the paper. All authors have participated in the work and have reviewed and agreed with the content of the article.

Conflicts of interest disclosure

None declared.

Research registration unique identifying number (UIN)

NA.

Guarantor

Okereke Promise Udohchukwu.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Acknowledgements

The authors appreciate Professors Felix Chukwuneke and Agozie Ubesie for inspiring us into observing and attending to cases.