Introduction

The Chikungunya virus (CHIKV) is a positive-sense RNA virus in which the genus for this virus is Alphaviridae. Viral transmission typically occurs due to an enzootic cycle where primates act as a reservoir, and these mosquitoes transmit the virus to humans. Humans who suffer from CHIKV infection proceed to infect Aedes aegypti mosquitoes, which infect more humans in a positive feedback loop.¹ Mosquito eggs are laid in water; therefore, open water sources and water storage spaces are home to many Aedes mosquitoes. Other Aedes mosquitoes include A. africanus, furcifer-taylori and dalzieli.

The mosquito spread to primates is known as the sylvatic cycle, and the human spread is referred to as the urban cycle.¹ This alpha virus leads to musculoskeletal pain alongside acute fever and is mainly spread in tropical areas such as regions of South America, Asia, the Caribbean, and Africa. CHIKV is less prevalent in Europe and the Middle East; however, cases have recently increased. The Indian Ocean is synonymous with CHIKV, as the first reported cases occurred in Mozambique. At the time, symptoms were thought to be caused by the dengue virus.² Public health systems in these affected regions, many of which are not high-income countries and areas which are typically less developed, have been greatly affected by this virus. This article will explore the mechanisms behind CHIKV and delve into how this affects public health systems in affected regions. Management strategies and future directions will also be explored.

Epidemiology of chikungunya

Throughout history, there have been a number of CHIKV outbreaks. CHIKV was first isolated in 1952 on the Tanzanian border region shared with Mozambique, in which a patient showed symptoms resembling Dengue fever. An epidemic in this region led to CHIKV being isolated in a serum, although at this point, CHIKV had not been reported. Antibodies for the virus were collected in 1962, 1964 and 1969 in Thailand, India and Nigeria, respectively. The first cases, however, occurred in Indonesia during 1973. CHIKV outbreaks were reported in this region till the early 1980s and did not resurface till 2003.³

Recent outbreaks occurred in 2016 in India, followed by Bangladesh in 2017, as well as Thailand and Myanmar. There have been some incidents in South America, such as in Brazil and Paraguay.⁴ Seasons affect the prevalence of CHIKV, with peaks being reported in some countries, such as Portugal, in summer and winter, with the most cases occurring between March and April.⁵ As mosquitoes thrive in a humid environment, CHIKV is seasonal, as during summers, there is higher humidity and in tropical climates, rainfall occurs regularly; mosquitoes can also thrive in a cold climate where humidity can be high due to intense rainfall.⁶ High-risk individuals include elderly people, as this can lead to cardiac alterations. Older people are also more susceptible to cognitive decline as a result of this virus; therefore, this group must be protected.⁷ Patients with pre-existing conditions, particularly those that are rheumatological in nature (inflammatory), are more likely to suffer complications following CHIKV infection.⁸

Clinical manifestations and disease burden

CHIKV symptoms are similar to Dengue fever. The typical symptoms include a fever alongside a rash, and headaches; the long-term symptoms are severe and can include joint pain as a result of arthritis. Polyarthralgia is a common long-term symptom where joint pain persists for an extended period of time; these patients also present with fatigue that can affect the quality of life for those affected.⁹ Mortality rates vary greatly depending on the region affected, with some outbreaks leading to over a 33% mortality rate, contrary to some studies showing a 0.3% mortality rate, therefore demonstrating that high-risk populations are much more likely to die as a result of CHIKV.¹⁰ Quality of life differs greatly between ages and genders, with mental component scores being much lower for females, indicating worse overall health. The quality of life is also lower in the elderly due to a higher chance of disability, typically either due to arthritis or a decline in cognitive ability.¹¹

Impact on public health systems

CHIKV affects public health systems in many different ways. Firstly, many hospital employees and healthcare staff may get infected by this illness, which puts a large amount of strain on patient treatments, which are also very expensive. Special medical assistance is required for those with chronic CHIKV who present with symptoms such as joint pain. The overall demand for healthcare is an issue during outbreaks.¹² As aforementioned, CHIKV can have financial implications as treatment is very expensive, as well as patients with mobility issues as a result of CHIKV taking sick leave under these circumstances, leading to the overall economy being negatively affected. As previously mentioned, fewer healthcare staff are available if they are infected.¹³ Diagnosis is difficult as PCR assays are expensive, and diagnostics are not optimal. Vectors that spread the disease, such as mosquitoes, also need to be controlled, which is difficult.¹⁴ Vaccines, as well as antivirals, are constantly being developed; however, they are not all effective, and there is no well-accepted treatment for this disease. Thus, treatments will need to be explored, which is costly.¹⁵

Public health response and management strategies

There are ways to manage this virus. Managing vectors such as mosquitoes, such as repellents and nets, is known to lower infection risk, and larvicides alongside insecticides prevent reproduction. Awareness is crucial, as it will prevent stagnant water and storage spaces from being highly prevalent, thereby managing the primary vector for this infection.¹⁶ Educating people on the risks is the most effective way to reduce future cases. To manage acute symptoms, anti-inflammatory drugs that are not steroids, such as ibuprofen, which are available over the counter, are used for symptoms such as headaches and fever. Chloroquine, as well as a low dosage of certain steroids, has been previously used for arthritis during chronic CHIKV due to its effectiveness in malaria cases.¹⁷ Rehabilitation exercises following chronic conditions, such as walking and using stairs, are crucial for recovery and are recommended.¹⁸ Research and development are necessary to develop effective vaccines and antivirals, which will be expensive. Collaborative efforts to facilitate clinical trials will be crucial in the effort to eradicate this rare illness.¹⁹

Case studies of affected regions

Many regional outbreaks have occurred. Countries situated near the Indian Ocean, such as Mozambique and other African countries, have been greatly affected, as well as other Asian countries, including India and Thailand. Much of the literature regarding CHIKV is due to Brazilian cases.² Ovitraps in Thailand, Brazil, Peru, and Bangladesh significantly reduced the number of mosquitoes per household, demonstrating their efficacy in tropical countries. These are mosquito traps that mimic egg-laying areas.²⁰ In Eastern India, recently, infection monitoring and anti-inflammatories have effectively treated instances; however, chronic symptoms are difficult to treat. In countries such as India, CHIKV is hard to detect and treat, as during the monsoon season, there are many other illnesses which present similar symptoms. However, detection is improving drastically with time.²¹ As previous conditions increase the mortality likelihood, it has been established that preventing chronic illness prevalence, such as diabetes, particularly in lower-income countries, will greatly reduce CHIKV prevalence and mortality rates.²²

Long-term implications for public health systems

To combat CHIKV, there is a need for public health infrastructure to be improved, and diseases that are spread by vectors such as mosquitoes need to be increasingly monitored to prevent CHIKV risk. Climate change is likely to affect future CHIKV prevalence; thus, in countries with large vector numbers, this will need to be monitored.²³ Improving healthcare access, particularly in lower-income countries, will help those affected receive treatment and will inevitably decrease the prevalence of this virus. Communities affected by CHIKV will greatly benefit from improved access to healthcare, and this will help prevent the barriers faced by those individuals from a lower socio-economic background who are typically more susceptible to this illness.

Conclusion

To conclude, chikungunya virus tends to predominantly affect those living in tropical countries, and the continents affected include South America, Asia and Africa. CHIKV is challenging to detect due to the presumed symptoms, such as headaches and fatigue, being very similar to other illnesses. CHIKV has had a great impact on affected communities on public health systems, such as healthcare staff being less readily available, as well as managing symptoms, having considerable financial implications on public health systems. This burden will be alleviated in the future if vaccines and antivirals suited for CHIKV are designed and developed; however, this will require extensive research. Those who are vulnerable need to take extra measures to ensure they avoid being affected through vector transmission. This includes limiting water storage spaces to prevent mosquito breeding and using insecticides. Increasing awareness will be integral to decreasing the likelihood of CHIKV. Although diagnosis and treatment are difficult for those affected, research and development will hopefully make this disease far less prevalent in the future.