Big­ger threat

Down to Earth - - FOREST DISEASE - DOWN TO EARTH

Tamil Nadu also died from kfd last De­cem­ber. In 2013,a case was re­ported from the Mudu­malai Tiger Re­serve in Tamil Nadu’s Nil­giri dis­trict. In Novem­ber 2012, few hu­man cases were re­ported from Kar­nataka’s Bandipur Na­tional Park, which also reg­is­tered the death of a few mon­keys by the dis­ease.

Lit­tle is known about the rea­sons be­hind the spread of the dis­ease be­cause there is hardly any re­search on it.But it is es­tab­lished that de­for­esta­tion could be the pri­mary rea­son as it in­creases the con­tact be­tween hu­mans and wild an­i­mals. Shiva­mogga dis­trict alone lost 4,000 hectares of for­est be­tween 2001 and 2007.There is ev­i­dence that global warm­ing that in­creases pop­u­la­tion of in­sects like ticks that har­bour the virus could also lead to the spread of the dis­ease.

Even within a taluk, out­breaks are not re­ported from the same area. “The dis­ease keeps mov­ing from one area to an­other dur­ing dif­fer­ent epi­demic sea­sons,” says Ra­jesh Surgi­halli, deputy direc­tor,Virus Di­ag­nos­tic Lab­o­ra­tory,Shiva­mogga,and the state’s nodal of­fi­cer in-charge of mon­i­tor­ing the dis­ease.

Trans­mis­sion through ticks

Mon­keys are the pri­mary car­rier of the dis­ease. Ticks ( Hema­physalis spinig­era) that live on them,har­bour the pathogen and pass it among the monkey pop­u­la­tion.“Mon­keys are sure to die once in­fected,”says Prakash K S, health of­fi­cer of Thirtha­halli taluk. When in­fected mon­keys die, ticks drop from the dead bod­ies to the ground, thereby gen­er­at­ing hot spots of in­fec­tious ticks that fur­ther spread the virus. It is trans­mit­ted to hu­mans through the bite of a tick or when hu­mans come in con­tact with an in­fected an­i­mal. (See ‘Kyasa­nur for­est dis­ease virus ecol­ogy’ p14.) The out­break of the dis­ease in hu­mans gen­er­ally oc­curs in the dry months, from Jan­uary to May.

Once in­fected by the virus,it takes three to eight days for symptoms to ap­pear. “Pa­tients may ex­pe­ri­ence ab­nor­mally low blood pres­sure, and low platelet, red blood cell and white blood cell count,”says Prakash. Most pa­tients re­cover within a week or two. But the ill­ness has a sec­ond phase. Only 1020 per cent pa­tients reach the sec­ond phase. “The sec­ond wave of symptoms be­gins from

K A R N ATA K A the third week of the ill­ness.Th­ese symptoms in­clude fever and neu­ro­log­i­cal dis­or­ders,” says Surgi­halli. The World Health Or­ga­ni­za­tion and the Cen­tres for Dis­ease Con­trol and Pre­ven­tion have clas­si­fied this virus into group-4,which means the virus can cause se­vere hu­man dis­ease and is a se­ri­ous haz­ard to lab­o­ra­tory work­ers.

There is no ef­fec­tive treat­ment for the dis­ease and though a vac­cine is avail­able since 1989, it is not popular. At Thirtha­halli, only 30 per cent of the peo­ple are cov­ered un­der the vac­ci­na­tion pro­gramme as of now.While the vac­cine can­not pre­vent the dis­ease since its ef­fi­cacy is only 65 per cent, it can com­pletely pre­vent the sec­ond stage of the dis­ease.“That means, the vac­cine can pre­vent deaths,” says Surgi­halli. De­spite vac­ci­na­tion drives by the gov­ern­ment, kfd cases in the state in­creased be­tween Jan­uary 1999 and 2005,says a 2006 pa­per pub­lished in Re­views in Med­i­cal Vi­rol­ogy. The lead re­searcher, Priyabrata Pat­tnaik from the De­fence Re­search and Devel­op­ment Estab­lish­ment in Gwalior, writes that “there is clearly a need for de­vel­op­ing an al­ter­na­tive vac­cine as well as a rapid di­ag­nos­tic sys­tem for kfd”.

An­other is­sue is that till last year, state health depart­ment guide­lines al­lowed kfd vac­ci­na­tion only for the six to 65 age group. The guide­line was based on the as­sump­tion that chil­dren un­der six and adults above 65 will not visit forests for work.The as­sump­tion is mean­ing­less be­cause many dis­ease-prone ar­eas lie within forests or in their vicin­ity. This year, the au­thor­i­ties have changed the guide­lines to in­clude those above 65 in the vac­ci­na­tion pro­gramme. But the un­der-six group is still not vac­ci­nated. The rea­son: the vac­cine has not been tested for its ef­fects on chil­dren even though it has been in use for 25 years.None of the gov­ern­ment hos­pi­tals in Kar­nataka has lab­o­ra­to­ries that can carry out tests to di­ag­nose kfd in pa­tients. For con­duct­ing the re­quired tests, lab­o­ra­to­ries need to have high biosafety fa­cil­i­ties since there are pos­si­bil­i­ties of in­fec­tion. Only one hos­pi­tal, the pri­vate Ma­ni­pal Med­i­cal Col­lege,has blood test fa­cil­i­ties for kfd in the state. “We are in the process of set­ting up fa­cil­i­ties in the Shiva­mogga lab. It will be op­er­a­tional in a few months,”says Surgi­hally.

Ex­perts say the gov­ern­ment has ne­glected the dis­ease so far be­cause it was con­fined to a few ar­eas and has a low fa­tal­ity rate for hu­mans.Pat­tnaik,in his pa­per,writes that the emer­gence of kfd in var­i­ous states em­pha­sises the need for na­tion­wide sur­veil­lance among an­i­mals and hu­mans.

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