Abstract Chikungunya fever is a rare form of viral disease characterized by fever, severe arthralgias, rash spread by Aedes mosquitoes. Since late 2005, Chikungunya fever has been causing extensive outbreaks in several islands in south west Indian ocean including Reunion Islands, Seychelles, Mauritius, Mayetta and Madagascar.
In India it was reported in late 2005 in Karnataka and in December 2005 in Andhra Pradesh, where it started as an urban phenomenon and has since then spread to more than 1400 villages in southern India. Other regions in grip of this unprecedented epidemic are certain regions of Tamilnadu, Maharashtra, Orissa and Madhya Pradesh. Unofficial figures point to lakhs of cases having been reported in last six months from affected states.
We present an overview of this rare disease, including clinical features, investigations and treatment for the illness.

History

The rather difficult to pronounce ‘Chikungunya’ name comes from ‘Swahili’ a language spoken in East Africa which literally means “that which bends up” in reference to stiff joints which is the main symptom of the disease. The Virus causing Chikungunya fever also known by other names like as BUGGY CREEK virus and CHIKV. The disease was first described in 1953, following an outbreak of Chikungunya fever on border between Tanganyika and Mozambique. This virus is mainly found in Africa and many countries of South East Asia. Chikungunya fever has been causing extensive outbreaks in several islands in Southwest Indian ocean including Reunion Islands, Seychelles, Mauritius, Mayetta and Madagascar.^1-4

Unlike public perception this disease has nothing to do with poultry, instead it is a viral fever spread by day time biting mosquitoes of genus Aedes i.e. Aedes aegypti, Aedes albopicticus (Tiger Mosquito). Interestingly both of these types of mosquitoes also spread the dreaded dengue fever, as infected Aedes mosquito can carry both the viruses at same time. There are recorded instances where a person, has had both Chikungunya fever and Dengue fever together at the same time. With the possibility of Dengue raising its head once again in rainy season this combination of a dual epidemic can prove to be Catastrophic.

Extent of Problem

CHIK V is responsible for extensive Aedes aegypti-transmitted urban disease in cities in Africa and major epidemics in Asia. The crippling Arthralgias and frequent Arthritis that accompany the fever and other systemic symptoms are clinically distinct. Like CHIK several other Togaviruses of the alpha virus genus (Ross River, O’ nyong-noyng, etc.) have been associated with a similar syndrome. CHIK activity in Asia has been documented since its occurrence in Bangkok in 1958.

Other countries in South East Asia which have reported CHIK activity include Cambodia, Vietnam, Srilanka, India, Indonesia, and the Philippines. In India the first epidemic of this disease was recorded in Calcutta in 1963,5 and last outbreak of infection occurred in India in 1971. No active surveillance of this disease was done after that and it was assumed that the virus had ‘disappeared’ from the subcontinent.6 It was soon a forgotten disease and hence it is not surprising that most present day health care providers have not even heard of this disease.

Clinical Features

CHIK V is an acute infection of abrupt onset heralded by fever and severe arthralgia, followed by other constitutional symptoms and rash, and lasting for a period of 1-7 days. The incubation period is usually 2-3 days, with a range of 1-12 days. Fever rises abruptly, often reaching 39 to 40 degrees celsius and accompanied by intermittent shaking chills. This acute phase lasts 2-3 days. The temperature may remit for 1-2 days to come back again, resulting in a “saddle-back” fever curve. In the present epidemic patients are describing severe gastro enteritis accompanied with colicky pain in abdomen, which takes about four to five days to settle down.

The joint pains are polyarticular, migratory, and predominantly affect the small joints of the hands, wrist, ankles and foot, with lesser involvement of larger joints. Joint Swelling may occur, but effusion in joints is uncommon, Patients with milder articular manifestations are usually symptom-free within a few weeks, but more severe cases require months to resolve entirely. Generalized myalgia, as well as back and shoulder pain is common.

Cutaneous manifestations are typical with many patients presenting with a flush over the face and trunk. This is usually followed by an erythematous rash generally described as maculopapular. The trunks and limbs are commonly involved, but face, palms and soles may also show lesions. Pruritus may accompany the rash. In this present epidemic there are reports of severe peeling of skin few days after the appearance of rash. The increased severity of arthritis and rash are ascribed to mutation in this virus which has acquired aggressive form in this epidemic.

During the acute disease, most patients will have headache, but it is not usually severe. Photophobia and retro-orbital pain also occur but are not severe. Conjunctival injection is present in some cases. Some patients will complain of sore throat and have pharyngitis on examination.

CHIK V infection has a somewhat different picture in younger patients. Arthralgia and arthritis occur but are less prominent and last a shorter time. Rash may be less frequent; but in infants and younger children, prominent flushing and early appearance of maculopapular or urticarial skin rash may be a useful indicator. The disease is self limiting and rarely fatal. The complications although rare are seen mostly in affected children who include meningoencephalitis and pneumonia.7 Recently some late complications of this disease have been reported.

Global changes in human activities and ecological factors have led to many emerging and re-emerging infectious disease in recent years. CHIKV, a forgotten disease in India has now caused an outbreak, thirty-five years after it was described in India for the last time. The Re-emergence of this long dormant infection has been a subject of lot of research and discussion in the medical community. A study on virus isolated from Reunion Islands outbreak was studied at Pasteur Institute in Paris by Sylvian Brisse and colleagues and it was found that the present virus has mutated itself to a more “aggressive” from than its predecessor which originated in Africa and had caused earlier outbreaks in parts of Africa and Asia. The present strain has novel and unique molecular features. It is the result of this “mutation” in the virus that in the present Indian out break cutaneous manifestations such as rash are more severe and arthritis is persisting for prolonged periods.

Some authorities however believe that the absence of infection in India for more than three decades has led to absence of Herd immunity against this virus in people and could be reason for rapid spread of infection, while others blame it on exponential increase in population of mosquitoes especially of genus Aedes in recent times.

Diagnosis

CHIK can be diagnosed by Serology, Virus isolation or Nucleic acid amplification depending on the timing of patient’s blood specimen in relation to onset of symptoms. The gold standard and most specific test is viral culture in vero (monkey kidney) or C6/36 (Ae. Albopictus) cells or newborn mice. Isolation is most likely to be successful if the sample is collected in the first three days of illness. Reverse transcriptase-PCR is a powerful tool that can detect nucleic acid from non viable viruses, and thus may be used for blood samples obtained beyond three days. However, once the patients start producing antibodies, the probability of a positive culture or PCR decreases. IgM is detectable from 3-5 days by ELISA or indirect immunofluorescent assay and declines within three months. Convalescent sera may be tested for IgG by ELISA. Serological detection of IgM and IgG is most useful in retrospective diagnosis, particularly if a significant rise in antibody titer can be demonstrated.

As the symptoms of this disease resembles Dengue fever, it is very necessary to exclude it by blood tests as Dengue fever can be associated with complications of bleeding and shock, which can be life threatening. A Double infection with both Chikungunya and Dengue can occur together which can also be detected with Serological tests. Arthritis and a rash are not prominent symptoms of Dengue and thrombocytopenia, bleeding tendencies, shock are not prominent features of Chikungunya infection.

There are very few laboratories at present equipped to detect Chikungunya virus. Although a definitive diagnosis can only be made with Lab tests, however due to severe paucity of testing facilities, the disease should be suspected in an on going epidemic, in any patient presenting with triad of Fever, Joint pains and Rash. IgM capture ELISA test is necessary to distinguish it from Dengue fever. Many Indian cities because of their very high density of population, large slum dwellings and in this season of heavy rains are very vulnerable to outbreak of this epidemic.

Treatment

There is no preventive treatment for this disease and presently no vaccine is available. Once the patient develops this disease then symptomatic treatment including bed rest, plenty of fluids, vitamins and NSAIDs for joint pains are needed. ASPIRIN should be avoided as it may cause Gastrointestinal erosions in some patients who develop thrombocytopenia, which is some times seen. In this disease and in these patients Aspirin cause bleeding from gastrointestinal tract. Movement and mild exercise tend to improve stiffness and morning joint pains, but heavy exercise can increase the joint symptoms. Hydroxychloroquine is some times used for chronic arthritis not responding to NSAIDs which occurs in about 10 per cent cases. In states like Andhra Pradesh where acute phase of these diseases is subsiding now reports of late complications of the disease are pouring in. There are patients whose joint pains have recurred five to six weeks after the acute phase was over and are continuing for more than two months now. Many patients have developed late complications like severe Cellulitis after trivial injuries, not responding to usual antibiotics and needing higher generation of Antimicrobials. The cause of this is not known but is speculated to be due to decrease in immunity caused by this CHIKV.

Prevention

In view of very recent reports of few suspected cases from Mumbai, there is an urgent need on part of Govt to go on a war footing drive against mosquitoes. Fogging, larvacidal measures and intensified drive against rubbish and garbage disposal are need of the hour. Distribution of Insecticide treated nets, distributed free of charge in Kenya by their Govt. has resulted in almost eradicating mosquito borne illness like malaria to a large extent in that country, however for Indian Govt with our population burden it may be a Herculian task. Following precautions by people will go long way in curbing this menace of Chikunguyna,

1. People should get rid of any containers storing water such as buckets, old tyres, flower vases, food cans. Over Head Tanks should be properly covered
2. Wear full sleeves clothes and cover the legs especially at time of work, as it is a day time biting mosquito which spread the disease.
3. Cover all windows with mosquito preventive nets.
4. Use mosquito repellants and mosquito nets.
5. Urge your local health authorities for urgent fogging of your area.
6. Report any suspected case to health authorities.

References

1. Enserink M. Massive outbreak draws fresh attention to little-known Virus. Science 2006; 311 : 1085.
2. CDC. Chikungunya Fever in India. Travelers Health Outbreak Notice April 21, 2006.http://www.cdc.gov/travel.
3. Chikungunya and Dengue in the south West Indian Ocean. Epidemic and Pandemic alert and response (EPR). http://www.who.int/csr/don/2006.
4. Quatresous I. The Investagition group, E-alert 27 January:Chikgunya outbreak in Reunion, a French overseas department. Euro Surveill 2006; 11 : E060202.
5. Shah KV, Gibbs CJ Jr, Banerjee G. Virological investigation of the epidemic fever in Calcutta:isolation of three strains of Chikungunya Virus. Indian J Med Res 1964; 52 : 676-83.
6. Pavri K. Disappearance of Chikungunya virus from India and southeast Asia. Trans R Soc Trop Med Hyg 1986; 80 : 491.
7. Chatterjee SN, Chakravarti SK, Mitra AC, Sarkar JK. Virological investigation of cases with neurological complications during the outbreak of hemorrhagic fever in Calcutta. J Indian Med Assoc 1965; 45 : 314-6.

*Associate Professor and Unit Head; **Senior Resident, Department of Internal Medicine, MGM Medical College and Hospitals, Navi Mumbai.