Coverage and Effectiveness of Kyasanur Forest Disease (KFD) Vaccine in Karnataka, South India, 2005–10

National Institute of Epidemiology (ICMR), Chennai, India
PLoS Neglected Tropical Diseases (Impact Factor: 4.45). 01/2013; 7(1):e2025. DOI: 10.1371/journal.pntd.0002025
Source: PubMed


Kyasanur forest disease (KFD), a tick-borne viral disease with hemorrhagic manifestations, is localised in five districts of Karnataka state, India. Annual rounds of vaccination using formalin inactivated tissue-culture vaccine have been conducted in the region since 1990. Two doses of vaccine are administered to individuals aged 7-65 years at an interval of one month followed by periodic boosters after 6-9 months. In spite of high effectiveness of the vaccine reported in earlier studies, KFD cases among vaccinated individuals have been recently reported. We analysed KFD vaccination and case surveillance data from 2005 to 2010.
We calculated KFD incidence among vaccinated and unvaccinated populations and computed the relative risk and vaccine effectiveness. During 2005-2010, a total of 343,256 individuals were eligible for KFD vaccination (details of vaccination for 2008 were not available). Of these, 52% did not receive any vaccine while 36% had received two doses and a booster. Of the 168 laboratory-confirmed KFD cases reported during this 5-year period, 134 (80%) were unvaccinated, nine each had received one and two doses respectively while 16 had received a booster during the pre-transmission season. The relative risks of disease following one, two and booster doses of vaccine were 1.06 (95% CI = 0.54-2.1), 0.38 (95% CI = 0.19-0.74) and 0.17 (95% CI = 0.10-0.29) respectively. The effectiveness of the vaccine was 62.4% (95% CI = 26.1-80.8) among those who received two doses and 82.9% (95% CI = 71.3-89.8) for those who received two doses followed by a booster dose as compared to the unvaccinated individuals.
Coverage of KFD vaccine in the study area was low. Observed effectiveness of the KFD vaccine was lower as compared to the earlier reports, especially after a single dose administration. Systematic efforts are needed to increase the vaccine coverage and identify the reasons for lower effectiveness of the vaccine in the region.

Download full-text


Available from: Sanjay M Mehendale,
    • "The known natural hosts are Blanford rat (Rattus blanfordi), the striped forest squirrel (Funambulus tristriatus tristriatus), and the house shrew (Suncus murinus) (Dobler, 2010). The annual incidence of KFD in India is estimated to be 400–500 cases with seasonal outbreaks during January to June (Holbrook, 2012; Kasabi et al., 2013). The clinical manifestation of KFD is similar to OHF (Bossi et al., 2004). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Rickettsioses are caused by obligate intracellular bacteria within the genus Rickettsia, mainly transmitted by arthropods. Until recently, Mediterranean spotted fever (MSF) caused by Rickettsia conorii was considered the only tick-borne rickettsiosis in Europe. However, 'new' TBR have been described in Europe during last years. For instance, other subspecies such as R. conorii caspia and R. conorii israelensis have been involved in MSF. Dermacentor-borne necrosis erythema and lymphadenopathy/tick-borne lymphadenopathy (DEBONEL/TIBOLA) cases caused by Rickettsia slovaca, Rickettsia raoultii, and Rickettsia rioja been described in several countries where Dermacentor marginatus ticks (the mainly implicated vector) are present. Rickettsia helvetica has also been involved as a human pathogen in cases of fever with and without rash and in patients with meningitis and carditis. Other TBR such as lymphangitis-associated rickettsioses (LAR), caused by Rickettsia sibirica mongolitimonae, have been diagnosed in different European countries (France, Spain, Portugal and Greece). Rickettsia massiliae is considered an etiological agent of MSF-like illness in the Mediterranean basin. Furthermore, Rickettsia monacensis that is distributed all along Europe has been isolated from patients with MSF-like illness in Spain. Although Rickettsia aeschlimannii has been associated with MSF-like in Africa and is distributed in the Mediterranean area, no autochthonous human cases have been reported for Europe. Other Rickettsia species detected in ticks and unrelated to human disease (Candidatus Rickettsia kotlanii, Candidatus Rickettsia barbariae, Candidatus Rickettsia vini) could be potentially involved in the next years. Climate changes, among other factors, may contribute to the emergence of other rickettsioses or change their distribution. Lastly, African tick-bite fever (ATBF), caused by Rickettsia africae, is frequently diagnosed in Europe in patients returning from endemic areas.
    Ticks and Tick-borne Diseases 11/2012; 3(5-6). DOI:10.1016/j.ttbdis.2012.10.035 · 2.72 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Diarrhoea is one of the lead killers of children worldwide. This study was done with an aim to determine the knowledge, attitude and practice regarding diarrhoeal illness, its prevention and management in mothers of under- five children. A descriptive cross- sectional study; 125 mothers were randomly selected from an urban slum of Delhi and were interviewed using a structured questionnaire. 96% mothers defined diarrhoea appropriately. Most common perceived causes of diarrhoea were contaminated food and drinking water (80%). Though 83% mothers believed that clean drinking water prevents diarrhoea, yet water treatment was practiced by only 36%. Most mothers believed in (90%) and practiced (88%) hand washing with soap post-defecation to prevent diarrhoea. While only 31% had knowledge on importance of use of latrine, fewer (19%) accepted that safe disposal of stool was very important and just 58% reported practicing it. Less than a third of the mothers recognized critical signs of dehydration. 79% mothers recognized importance of increased fluid requirement and 70% practiced it for management of diarrhoea. Though 76% mothers used ORS, only 26% considered it as the mainstay treatment of diarrhoea. Also, 42% mothers had incomplete knowledge regarding proper preparation of ORS. Though only 22% were aware of the role of breastfeeding in prevention of diarrhoea, a positive attitude towards (74%) and healthier practice (90%) of exclusive breast-feeding was observed. Thus, we conclude that though the community knowledge, attitude and practices on diarrhoeal illness and its prevention is marginally satisfactory, the poor knowledge regarding signs of dehydration and relevance of ORS as primary management component is a matter of concern for child survival.
    The Journal of communicable diseases 01/2014; 46(3):13-21.
  • [Show abstract] [Hide abstract]
    ABSTRACT: No antiviral therapies are available for the tick-borne flaviviruses associated with hemorrhagic fevers: Kyasanur Forest disease virus (KFDV), both classical and the Alkhurma hemorrhagic fever virus (AHFV) subtype, and Omsk hemorrhagic fever virus (OHFV). We tested compounds reported to have antiviral activity against members of the Flaviviridae family for their ability to inhibit AHFV replication. 6-azauridine (6-azaU), 2' -C-methylcytidine (2' -CMC), and interferon-α2a (IFNα) inhibited the replication of AHFV and also KFDV, OHFV and Powassan virus. The combination of IFNα and 2' -CMC exerted an additive antiviral effect on AHFV and the combination of IFNα and 6-azaU was moderately synergistic. The combination of 2' -CMC and 6-azaU was complex, being strongly synergistic but with a moderate level of antagonism. The antiviral activity of 6-azaU was reduced by the addition of cytidine, but not guanosine, suggesting that it acted by inhibiting pyrimidine biosynthesis. To investigate the mechanism of action of 2' -CMC, AHFV variants with reduced susceptibility to 2' -CMC were selected. We used a replicon system to assess the substitutions present in the selected AHFV population. A double NS5 mutant S603T/C666S and a triple mutant S603T/C666S/M644V were more resistant to 2' -CMC than the wild-type replicon. The S603T/C666S mutant had a reduced level of replication which was increased when M644V was also present, though the replication of this triple mutant was still below that of wild-type. The S603 and C666 residues were predicted to lie in the active site of the AHFV NS5 polymerase, implicating the catalytic center of the enzyme as the binding site for 2' -CMC.
    Antimicrobial Agents and Chemotherapy 03/2014; 58(6). DOI:10.1128/AAC.02393-14 · 4.48 Impact Factor
Show more