The Epidemiology of Chikunguniya Viral Disease

Chikungunya is one of the debilitating viral diseases that is transmitted between humans through the bite of a female Anopheles mosquito. It is an Alphavirus that belongs to the family of Togaviridae which is a native of tropical Africa and Asia (Cunha & Trinta, 2017). The first description of the virus, where the name “Chikungunya” was coined was in 1952 in a place found in a province in southern Tanzania. ”Chikungunya” is derived from the Bantu language, Makonde ethnic group found in Tanzania and Mozambique to refer to the curved position or the stooped appearance that a patient adopts as a result of the debilitating arthralgia (joint pain). Since the description of the disease, in 1952, Chikungunya virus has caused millions of human infections across the globe. Examples of places that have suffered from Chikungunya infection include Africa, Asia, the islands of the Indian Ocean, the Americas, and Europe.

            Epidemiologically, since the epidemic of 1952 in Tanzanian, the outbreaks of chikungunya have been seen in Asian, African, European, and the American countries (Acosta-Reyes, Navarro-Lechuga & Martínez-Garcés, 2015). For a number of years, the level of infections in Africa had been relatively low until in 1999-2000 large outbreak in Democratic Republic of Congo and the Gabon Chikungunya outbreak of 2007. India experienced a large Chikungunya outbreak in 2006 and 2007. The islands of India that had the cases included Mayotte, La Reunion, Seychelles, Mauritius, and Comoros (Cunha & Trinta, 2017). During the 2006-2007 La Reunion outbreak, the reported cases numbered 266,000. This resulted in about 34% of the affected population of the island. Several South-East Asian countries as well affected by the Chikungunya outbreak. Over 1.9 million cases have been described in India, Maldives, Indonesia, Myanmar, and Thailand since 2005. Several Chikungunya viral infection were reported in Europe in 2006 (Anish et al., 2011). The countries that experienced the infection included France, Italy, Germany, Switzerland, Belgium, and England.  

In 2013, Americas reported the first autochthonous Chikungunya viral infection in Saint Martin islands. In more than 47 World Health Organization’s countries of the Americas, locally transmitted cases have been described since the island of St. Martin reported a case (Halstead, 2015). As of April 2015, Chikungunya-suspected cases in Americas have been over 1,379,788. During the same period, 191 deaths have also been connected to the disease. Cases of importation have been recorded in Mexico, Canada, and the USA. In 2015 in America, the Pan American Health Organization (PAHO) regional office received 693,489 suspected cases and 37480 confirmed Chikungunya cases report (”Chikungunya”, 2018). Of the suspected cases, Columbia bore the biggest burden having 356, 079 cases. Compared with the 2014 Chikungunya cases, the 2015 cases was less since, in the same region, the reported suspected cases were more than 1 million. Following more than 1000 suspected outbreak cases in 2016, Argentina reported the first Chikungunya autochthonous transmission. In Africa, Kenya reported Chikungunya outbreak that resulted in more than 1 700 suspected cases.

Chikungunya-human transmission is by the bite of an infected female Anopheles mosquitoes that belongs to the genus Aedes spp, predominantly the Aedes aegypti. The other one is the Aedes albopictus. These two species have also been found to be capable of transmitting other mosquito-borne viruses like dengue. Aedes aegypti has been found to the most efficient arbovirus mosquito vectors. This is because it is highly anthropophilic and the close proximity with which it lives with humans (Cunha & Trinta, 2017). The species is confined within the tropics and subtropics with indoor breeding sites like water storage vessels, flower vases, and artificial outdoor habitats. The second largest transmitter is the Aedes albopictus which mostly occur in the temperate and even cold regions and has spread and even become established Africa, Asia, Europe, and Americas areas. Aedes albopictus flourishes well in various water-filled habitats like the holes on the tree, coconut husks, bamboo stamps, and even artificial habitats like vehicle tires which they form their breeding sites.  Transmission can also be through blood donation, mostly in endemic areas. For example, blood donations were interrupted during the La Reunion epidemic by the French blood service (Cunha & Trinta, 2017). During this time, it was estimated that, had blood donations not been interrupted, of the 37,750 blood bags donated, 47 blood bags may have been contaminated. 

            The clinical manifestation of the disease is described by a sudden fever onset that is often followed by an intense arthralgia, a pain that may hinder even the daily simplest activities. This is after some days upon the bite by an infected mosquito. After the bite of a mosquito, the virus gets into the skin and into the blood circulatory system. The virus replicates initially within the fibroblast, spread through the bloodstream and then to the liver, muscles, joints, lymph nodes, spleen, and brain (Cunha & Trinta, 2017). Other accompanying symptoms are pain in the muscle, nausea, fatigue, and body rash. The most debilitating is the joint pain which may last for some days or even prolong to weeks. Chikungunya virus can cause both the acute and chronic disease. Infected victims often fully recover although in certain circumstances the pain of the joint may continue for quite a number of months or even years. Also to have been reported are the cases of neurological, eye, and heart complications, and the complaints of gastrointestinal. Even though serious complications are not common, the disease can contribute to the death of older people who have been seen to be much more vulnerable than children or younger individuals (Cunha & Trinta, 2017). Because the disease clinical manifestation somehow resembles that of dengue or Zika virus, Chikungunya disease may be misdiagnosed in areas where these other infections are common. Often, the infected persons’ symptoms may even go unrecognized when the infection is a mild one.  

Laboratory Diagnosis

            The chikungunya viral infection laboratory diagnosis is based on the isolation of the virus, identifying the viral RNA through molecular techniques like reverse transcriptase (RT) and real-time Polymerase Chain Reaction (PCR), and the IgM and IgG antibodies detection through serological tests such as enzyme-linked immunosorbent assays (ELISA) and rapid immunochromatographic tests. The molecular or serological tests choice is dependent mainly on the sample collection time.

            The viral isolation is performed with the samples that are collected approximately on the eighth day of viral infection or before (Cunha & Trinta, 2017). After about three days of inoculation in a variety of cell types, chikungunya virus produces a cytopathic effect. Chikungunya virus isolation confirmation may be through RT-PCR or immunofluorescence. Obtaining the result requires a long time even though the method of viral isolation is a highly specific one. A level 3 bioassay is required for this process.

            RT-PCR is a significant tool when an early diagnosis of the infection is required. This is mostly in the cases of the newborn meningoencephalitis and vesiculobullous dermatitis. In such cases, early diagnosis is significant for a successful and timely treatment. The technique provides a quick diagnosis that is sensitive with the permission of the detection of nucleic acid of the virus before the symptoms shows up or the seventh day of the infection.

            IgG and IgM anti chikungunya virus can be detected through serological tests like ELISA and immunochromatographic tests. The tests permits the detection of IgM from the fifth day after the start of the symptoms whereas the detection of IgG occurs only a few days later. The advantage of these tests is that they can be used in the field in locations that are hard to access without the need of a refrigerator. The results can be provided in 10-20 minutes.

Medical Treatment

            Currently, there is neither a specific anti-chikungunya viral drug nor vaccine for the treatment and the prevention of the infection respectively. Some of the several antiviral drugs that have been recognized to have effect against chikungunya virus are ribavirin, chloroquine, furin inhibitors, arbidol, and interferon alpha (Cunha & Trinta, 2017). The first attempt in the development of inactivated and attenuated vaccine against Chikungunya virus lead to low immunogenicity as well as the adverse effects like pain of the joints. There are various options that are currently being evaluated though. However, through multi-professional health research group, a treatment protocol has been developed for chikungunya associated pain.

            For moderate-intensity pain, the recommended prescribed drugs are dypirone and paracetamol. Tramadol hydrochloride can be used in cases of dypirone allergy. In pregnant and lactating mothers, the usage of these drugs should carefully be considered. For severe-intensity pain, opioids drugs like tramadol hydrochloride are recommended for the prescription. For pregnant women, the first option in relieving chikungunya-caused pain is paracetamol with the contraindication of Nonsteroidal anti-inflammatory drugs (NSAIDs) (Cunha & Trinta, 2017). The other measures encouraged in relieving pain are joint puncture that helps in draining fluids, resting of the inflamed joints with the use of an orthotic, and with the always gentle active and passive movement in order to avoid causing pain.

Prevention and Control of Transmission

Because there is no developed drug treatment and vaccine against chikungunya virus, a lot of effort, therefore, need to be directed against mosquitoes with the intensification of the effort before the transmission season, more so during and after rainy seasons as well as a period after the epidemic. Mosquito vectors with breeding sites that are in close proximity to the dwellings of man is a great risk for not only chikungunya viral disease but also other vectored-mosquito diseases like malaria (”Chikungunya”, 2018). Preventive and control measures are therefore necessary. Both the natural and the human-created breeding habitat sites that forms the mosquito breeding grounds need to be reduced and even elimination.

The containment of chikungunya outbreak through the elimination of the vector breeding sites requires the community’s joint effort, both at the household level as well as the institutional levels like schools, colleges, and hospitals. The biting periods of Aedes mosquitos are mostly during the daytime and between dawn and dusk. By the use of commercially available pyrethroids-based aerosols for spraying, the adult mosquitoes can be gotten rid of. Areas to be sprayed include bedrooms, bathrooms, and the kitchen with spraying activity coinciding with the peak biting hours like early morning and late evening (2018). Mosquito coils can also be used. In eliminating the potential larval habitats both in and around the house, all stagnant waters should be removed and any other lying items that may include empty containers and car tires.

Protection from mosquito bites during chikungunya outbreak involves the use of clothing that covers the whole body, use of repellents on skin exposed areas, and the use of insecticide-treated mosquito nets (2018). For those traveling in risky areas, a lot of precautionary measures need to be taken. These include carrying and using repellents, putting on long sleeves and pants, as well as ensuring that the rooms are fitted with screens so as to prevent mosquitoes from entering the house.

Conclusion

Chikungunya is one of the mosquito-borne arboviral diseases that is debilitating with the clinical manifestation described by the abrupt fever onset followed by severe joint pains. Millions of human-chikungunya caused infections have been reported in several countries in Asia, Africa, Europe, and Americas. With the spread of the virus via the blood, to the liver, muscles, joints, lymph nodes, spleen, and brain, a lot of complications are caused in the eye and the heart as well as the gastrointestinal and neurological complications. The viral infection laboratory diagnosis is based on the isolation of the virus, identifying the viral RNA through molecular techniques like reverse transcriptase (RT) and real-time Polymerase Chain Reaction (PCR), and the IgM and IgG antibodies detection through serological tests such as enzyme-linked immunosorbent assays (ELISA) and rapid immunochromatographic tests. Even though there is no anti-chikungunya drug and vaccine, health professionals have developed protocol procedures in the management of the chikungunya associated pain. Because the disease is mosquito-borne, intensification of the prevention and control measures have been targeted against getting rid of mosquitoes. However, there is still a research continuation aimed at coming up with better medical treatments.

References

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Acosta-Reyes, J., Navarro-Lechuga, E., & Martínez-Garcés, J. (2015). Chikungunya fever: history and epidemiology. Salud Uninorte, 31(3), 621-630. http://dx.doi.org/10.14482/sun.31.3.7486

Anish, T., George, B., Lawrence, T., Muthukkutty, S., Ramachandran, R., & Vijayakumar, K. (2011). Clinical Profile of Chikungunya Patients during the Epidemic of 2007 in Kerala, India. Journal Of Global Infectious Diseases, 3(3), 221. http://dx.doi.org/10.4103/0974-777x.83526

Chikungunya. (2018). World Health Organization. Retrieved 31 March 2018, from http://www.who.int/mediacentre/factsheets/fs327/en/

Cunha, R., & Trinta, K. (2017). Chikungunya virus: clinical aspects and treatment - A Review. Memórias Do Instituto Oswaldo Cruz, 112(8), 523-531. http://dx.doi.org/10.1590/0074-02760170044

Halstead, S. (2015). Reappearance of Chikungunya, Formerly Called Dengue, in the Americas. Emerging Infectious Diseases, 21(4). http://dx.doi.org/10.3201/eid2104.141723