It is a time that demands our attention to learn more to prevent the threat of the disease Chikungunya. The name Chikungunya came from `Makonde’ ethnic group in southeast Tanzania and northern Mozambique.
The word means bending up, referring to the posture developed as a result of the arthritic symptoms of the disease.
First identified in Tanzania in 1953 it was reported in India as an epidemic in 1964. In Bangladesh, the first case was found in 2008 in Rajshahi and Chapainawabganj districts.
After the Institute of Epidemiology, Disease Control and Research (IEDCR) noticed the presence of the disease In Dhaka in 2011, I had a thorough research and this article is a simplified version of my thesis `Chikungunya Fever: An Emerging Threat to Bangladesh’, published in the official `Journal of Medicine’ of Bangladesh Society of Medicine in January 2012.
Chikungunya is a relatively rare form of viral fever caused by an alpha virus that is spread by bite of ‘Aedes aegypti’ mosquito.
Chikungunya virus or CHIK virus is a Group IV(+)RNA virus belonging to family `Togaviridae’ with `Genus Alphavirus’ and species `Cikungunya’ virus.
Chikungunya virus is most commonly transmitted to humans through the bite of an infected mosquito, specifically mosquitoes of the Aedes genus, usually by `Aedes aegypti’, which usually bite during daylight hours. Various `Culex’ species are also involved in urban epidemics in Asia including Bangladesh.
Reasons for re-emergence of Chikungunya infection
l Absence of herd immunity-susceptible population
l Viral mutation
l Increased air travel, tourism.
l Virus never disappeared, simple resurgence.
Current scenario in Bangladesh
Recently an outbreak of Chikungunya fever has been discovered in Dhaka, Dohar & Nababganj of Dhaka district & also in Shibganj of Chapainababganj. According to IEDCR, so far, 250 samples have been collected, among them the virus has been identified in the body of 46 persons. According to the information collected so far, this is the 3rd outbreak in Bangladesh in 2017. The 1st one was in Poba upozilla in Rajshahi district affecting 32 people in 2008 and the 2nd outbreak was in Shathiya upazilla of Pabna in 2009.
This disease is biphasic:
1st phase: It consists of fever & severe joint, limb & spine pains. Myalgia & conjunctivitis may also be present. It may last for 6-10 days.
2nd phase: It begins after a febrile period of 2-3 days & is associated with an irritating rash over the body, particularly on surface of the limbs. Joint pain may persist occasionally without fever, for up to 4 months. Bleeding from gums & a positive tourniquet test have been seen in many patients & may lead to the infection being mistaken for dengue.
Mortality rate is estimated at 0.4% but in patients aged less than one year, it is as high as 2.8% & similarly in those aged more than 50 years, death rate increases.
Incubation period: It is usually 2-3 days, with a range of 1-12 days.
Chikungunya is an acute infection of abrupt onset characterised by fever & arthralgia, followed by other constitutional symptoms and rash & lasting for a period of one to seven days.
1) Fever: Fever rises abruptly often reaching 39 to 40 degree centigrade accompanied by intermittent shaking chills. This acute phase lasts two to three days. The temperature may remit for one to two days, resulting in a ‘saddle-back’ fever curve.
2) Joint-Pain (Arthralgia):
l Pain on movement is worse in the morning improved by mild exercise. Swelling may occur but fluid accumulation is uncommon.
l Patients with milder articular manifestations are usually symptom free within a few weeks, but more severe cases require months to resolve entirely & may lead to crippling arthritis.
l Generalised myalgias as well as headache, back & shoulder pain is common.
l Chronic joint pains are seen in about 1 in 10 cases of Chikungunya infection and may be mistaken for rheumatoid arthritis.
3) Cutaneous manifestation: A flush over the face & trunk, usually followed by a rash generally described as maculo-papular may appear. Sometimes rashes are accompanied by severe itching.
4) Photophobia & retro-orbital pain may also occur but not severe. Conjunctival infection is present in some cases.
5) Although rare, the infection can result in meningo-encephalitis especially in newborns & those with pre-existing medical conditions.
6) In pregnant woman the biggest risk is the possibility of transfer of virus to the foetus. In addition, delivery becomes complicated if the infection starts late in the pregnancy sometimes requiring caesarean section. The virus is not transmitted through the breast milk.
7) Chikungunya can be deadly for very old and newborns.
Suspect case: An acute illness characterized by sudden symptoms of fever with several of the following symptoms-joint pain, headache, backache, photophobia and rash.
Probable case: As above & positive serology (when single serum sample is obtained during acute phase or during the convalescence).
Confirmed case: A probable case with any of the following:
1) Four fold HI antibody difference in the paired serum sample.
2) Detection of IgM antibody.
3) Virus isolation from serum.
4) Detection of Chikungunya with virus Nueleic acid in sera by RT-PCR.
Differences among Dengue and Chikungunya are manifested as
Three main laboratory tests are used for diagnosing Chikungunya fever:
l Virus isolation.
l Serological tests of Blood in plain vial/serum
l Molecular diagnosis by Polymerase Chain Reaction.
Time of collection:
1st sample: 5 days after onset of illness for IgM detection as these antibodies appear at this time.
2nd sample: At least 7-10 days after the 1st sample.
l There is no specific treatment for Chikungunya. Main purpose of treatment is the management of fever and pain.
l Non-aspirin & non-steroidal anti inflammatory drugs are recommended. There is no role of antibiotics & antiviral agents.
l Movement & mild exercise tend to improve stiffness & morning joint-pain (Arthralgia).
l A healthy diet with fruits and vegetables and good sleep promote early recovery.
l Chikungunya is rarely fatal. Recovery from the disease varies by age. Younger patients recover within 5 to 15 days; middle-aged patients recover in 1 to 2.5 months.
Recovery is longer for the elderly.
Vaccine against Chikungunya:
l Currently there are no vaccines available in the market for preventing Chikungunya.
l However scientists have developed an experimental Chikungunya vaccine, that contains noninfectious virus-like particles that enables Chikungunya virus to pass through cell walls.
l However, these particles do not contain replicable Chikungunya-proteins and hence is harmless but to be used with caution.
Prevention & Control:
l Vector control is thus very important in preventing Chikungunya transmission. Elimination of breeding sites or source reduction is an effective method of control.
‘Aedes aegypti’ is typically a container habitat species & breeds primarily in artificial container & receptacles.
l The best way is to encourage people to eliminate the mosquito habitats by emptying water containers once a week & keeping the permanent water containers covered with a tight fitting lid.
l Personal protection like long sleeve clothes, coverings, use of repellents, window nets play limited but useful role.