O’Nyong Nyong Virus - Transmission, Symptoms, Prevention, and Management.

Introduction

Mosquitoes commonly cause malaria and dengue by acting as carriers for the infection-causing organism and transmits the disease through their bite. For example, an infected Anopheles mosquito bites humans and transfers the virus into the bloodstream. Malaria and dengue are widely seen in African and Asian countries such as India. However, less commonly seen, the o’nyong nyong virus causes viral fever.

O'nyong nyong virus (ONNV) spreads through a mosquito bite, especially the Anopheles funestus and Anopheles gambiae mosquito. The symptoms of this virus are similar to chikungunya. Sometimes, it is difficult to differentiate between both viruses. An antibody test is helpful to distinguish between both viral fevers. Unfortunately, there is no specific treatment available. However, antipyretics, non-steroidal anti-inflammatory drugs, and other drugs may help subside symptoms.

What Is ONNV?

ONNV is an alphavirus that spreads or transmits through mosquitoes. Alphavirus is a single-stranded RNA virus that belongs to the Togaviridae virus family. These viruses are mainly transmitted through arthropods, mainly mosquitoes. The other examples of alphavirus include the Chikungunya virus and the Ross river virus. These viruses have the ability to infect both the vector, such as a mosquito and the host, such as the human body.

What Is the History of ONNV?

• The word “o'nyong nyong” comes from Uganda and means “weak joints.”

• It is closely related or similar to the virus that causes chikungunya and arthritis.

• The first viral infection occurred in 1959 in Uganda and 1963 in Senegal.

• This virus frequently spread within the African region between 1959 to 1963.

• The Igbo-Ora virus is one strain or variant of the o'nyong nyong virus, named after a village in West Africa where it was first reported.

• The first epidemic affected two million people.

• The second epidemic was reported in Uganda in 1996 and affected one million people.

• The third outbreak of this virus occurred in 2003 on Ivory Coast.

What Is the Geographical Distribution of ONNV?

The o'nyong nyong virus is limited to different countries of Africa, such as:

• West Africa.

• Ghana.

• Nigeria.

• Senegal.

• Central and East Africa.

• Kenya.

• Malawi.

• Mozambique.

• Uganda.

• South Sedan.

How Is ONNV Transmitted?

The virus is transmitted to humans through infected mosquitoes, called Anopheles funestus and Anopheles gambiae. The larvae of these mosquitoes are found in clear water bodies, unlike malaria-causing mosquitoes.

What Is the Incubation Time Period of ONNV Fever?

The incubation period of the o'nyong nyong is generally two to three days and may range from 1 to 12 days. The incubation period is the time between the bite of the infected mosquito and the appearance of the first symptom. Every virus has a different incubation period and may vary from patient to patient.

What Are the Symptoms of ONNV?

The symptoms include:

• Fever.

• Pain in joints for a prolonged time.

• Headache.

• Rashes and itching on the skin.

• Redness in eyes.

• Swelling of the lymph nodes.

• Bleeding from gums and nose is rare.

How Is ONNV Diagnosed?

1. Medical History - The patient will represent symptoms or clinical features similar to chikungunya, such as fever with or without chills, joint pain from several months, and so on. The patient will also have swollen lymph nodes which is not a clinical feature of chikungunya.

2. Blood Test - A blood test to measure antibodies that neutralize the effect of the virus in the patient’s body will be helpful. A commonly used test is the reciprocal plaque reduction neutralization test. This test helps the doctor to differentiate between Chikungunya and O Nyong Nyong virus.

3. Reverse Transcription-Polymerase Chain Reaction Test - It is commonly called the RT-PCR test and is the gold standard for diagnosing human viral infection. The patient's blood sample is collected, and the pathologist extracts the genetic material (RNA) both from the virus and the patient. A fluorescent dye is used to identify the presence of the virus in the RNA. The test results are positive or negative, coming in eight hours. Generally, the IgM antibodies are found in the blood test during the second week of infection.

How Is ONNV Treated?

The o'nyong nyong virus is a self-limiting infection and does not require any specific treatment.

• There is no vaccine available against o'nyong nyong virus infection.

• Symptoms such as fever may be treated through antipyretics.

• Non-steroidal anti-inflammatory drugs may help in reducing pain.

• The topical application of Corticosteroids may help in reducing joint pain.

How to Prevent ONNV Infection?

• Therefore, the best prevention method is using bed nets and other mosquito repellents to prevent mosquito bites.

• Use personal protective measures such as wearing fully covered clothes with long sleeves.

• Close the windows of the house with screens.

What Is the Differential Diagnosis of ONNV?

• Chikungunya: A viral fever caused by virus transmission through an infected mosquito bite.

• Osteoarthritis: Disease of joints that commonly affects knee joints, hand joints, neck joints, and others.

• Rheumatoid Arthritis: Inflammatory, an autoimmune disorder that affects joints of hands and feet.

• Psoriasis: Skin disease that includes rashes and itching on the skin.

• Gonorrhea: Bacterial infection that spreads through sexual activity in males and females.

How Is ONNV Different From Chikungunya?

The o'nyong nyong virus is similar to Chikungunya. The difference lies in:

• The swelling of lymph nodes is more often in o'nyong nyong virus fever.

• The pain in joints occurs without the collection of fluid in the spaces present between the tissues (effusion) in o'nyong nyong virus fever.

Conclusion

O'nyong nyong virus is a geographically restricted mosquito-borne virus that is self-limiting. It means the fever due to this virus occurs suddenly and subsides on its own. It causes fever, joint pain (viral arthritis), rashes, and many other symptoms. Unfortunately, there is no specific treatment available. The symptoms are treated with antipyretics, non-steroidal anti-inflammatory drugs, and others.