“That which bends up” is
what the word “Chikungunya” means in Kimakonde, an African language. It’s quite
an apt word considering the effect this infection has on those affected by it!
Chikungunya is a fever
spread by a virus that is transmitted by the female mosquito. Female mosquitoes
need proteins from mammalian blood for their eggs to develop, which is why they
bite humans. Certain viruses like the dengue and chikungunya viruses
collectively called arboviruses (ARthropod BOrne viruses) make use of this
requirement of the mosquitoes to ensure their own survival. These viruses were
originally present only in the forest areas infecting primarily monkey species.
Humans were just incidental hosts. But now due to the impact of
industrialisation and loss of forest cover, these viruses have made humans as
their permanent hosts. The virus cannot spread from one human to another but
can spread only by mosquitoes which get infected while biting an infected
individual, thereafter transmitting the virus by biting an uninfected
individual.
So, how does chikungunya
virus spread and act on the body? Once a mosquito bites, the virus spreads
through the epidermal cells of the skin and reaches the inside of the body
through the blood stream. The virus primarily targets muscle, joint and skin
fibroblasts where the maximum damage occurs. This is the reason why patients
experience intense joint pain and swelling along with rashes and acute(intense,तीक्ष्ण) fever. Apart from the
tissues, a person’s immunity-mediated response is another important factor that
dictates the severity of the disease. This explains why immune-compromised
individuals such as very young children and elderly persons are more severely
affected by this virus. This is also the reason why individuals with other
underlying health complications such as like diabetes and cardiovascular
diseases experience have more drastic effects due to the infection. It has to
be emphasised at this point thatwhile chikungunya results in extreme morbidity(illness,रुग्णता) and a prolonged(long,लम्बा) phase of physical
disability, it is not a fatal disease.
Patient management
A primary concern with
respect to chikungunya treatment is effective diagnosis. At present there are
no virus-specific detection methods and we have to resort to employing
antibody-specific testing which delays diagnosis by a great extent. A study
conducted by our group and our collaborators at Nair Hospital in Mumbai showed
that almost 10 per cent of dengue patients were co-infected with the
chikungunya virus but they were not even treated for the disease. This is a big
blow to patient management and disease management. While we were able to detect
these co-infections because we employed reverse transcription-polymerase chain
reaction (RT-PCR) to detect both the viruses, this is not practical in a
hospital setting with a huge patient load and the lack of trained personnel.
One may argue that dengue is more dangerous than chikungunya due to the
complications of dengue as opposed to the non-fatal condition of chikungunya.
But one must remember that patient management is quite different for both these
infections and has several implications on disease prevention.
The vector plays an
extremely important role in the spread of the chikungunya virus. When
chikungunya struck in 2005, the reason it was such a huge pandemic was because
the virus had mutatedtransform,रूपांतरित) its outside coat protein
by a single amino acid that allowed it to replicate faster in another species
of Aedes. This allowed the vector to transmit the virus more effectively. In
the 2010 outbreak, virus strains sampled from different parts of the country
were found to contain mutations on precisely(clearly,स्पस्थ्तया) three sites on their
genomes. Sequencing the genome of the virus associated with the current
outbreak in North India may reveal new information as to why the outbreak has
been so explosive this time. Has the virus mutated again to become more virulent(poisonous,विषैला)?
Control the key
Whatever be the nature of
the virus, the only effective method to control this hugely debilitating(weak,दुर्बल) infection is intense vector control and
public health awareness programmes. The Mosquitoes serve as reservoirs for
these viruses where the viruses survive in low amounts until they can infect a
population. Having said this, we are talking of multiple issues here — the number
of mosquitoes in nature at a given point in time and the amount of chikungunya
virus within these mosquitoes. We recently conducted a survey where we
addressed both these issues. We observed that the Aedes mosquitoes were present
in small numbers even during the dry season and the viruses were present in
these mosquitoes through generations. A single heavy shower was enough for the
mosquito population to explode and along with it the virus populations within
the mosquitoes. Every time it is a disaster waiting to happen. When the
mosquito and the virus population reach a critical number, it results in
outbreaks. Therefore, the only way to prevent this by is curbing(control,नियंत्रण) the mosquito population
before the monsoon starts.
We face multiple issues
with respect to chikungunya disease control in our country. A lack of sensitive
virus-specific diagnostic tools, an absence of drugs/vaccine, poor vector
control measures and public awareness contribute tremendously in escalating the
problem. It is no surprise then that India is considered as the hub for
chikungunya spread across the globe.
courtesy:the hindu
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