Intensely clustered outbreak of visceral leishmaniasis (kala-azar) in a setting of seasonal migration in a village of Bihar, India
Intensely clustered outbreak of visceral leishmaniasis (kala-azar) in a setting of seasonal migration in a village of Bihar, India
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Abstract Background A visceral leishmaniasis outbreak was reported from a village in a low-endemic district of Bihar, India.Methods Outbreak investigation with house-to-house search and rapid test of kala-azar suspects and contacts was carried out.Sandfly collection and cone bio-assay was done as part of entomological study.
Results A spatially and temporally clustered kala-azar outbreak was found at Kosra village in Sheikhpura district with 70 cases reported till December 2018.Delay of more than a year was found between diagnosis and treatment of the index case.The southern hamlet with socio-economically disadvantaged migrant here population was several times more affected than rest of the village (attack rate of 19.
0% vs 0.5% respectively, ORMH = 39.2, 95% CI 18.
2–84.4).The median durations between onset of fever to first contact with any health services, onset to kala-azar diagnosis, diagnosis to treatment were 10 days (IQR 4–18), 30 days (IQR 17–73) and 1 day (IQR 0.
5 to 3), respectively, for 50 kala-azar equi-jec 7 cases assessed till June 2017.Three-fourths of these kala-azar cases had out-of-pocket medical expenditure for their condition.Known risk factors for kala-azar such as illiteracy, poverty, belonging to socially disadvantaged community, migration, residing in kutcha houses, sleeping in rooms with unplastered walls and non-use of mosquito nets were present in majority of these cases.
Only half the dwellings of the kala-azar cases were fully sprayed.Fully gravid female P.argentipes collected post indoor residual spraying (IRS) and low sandfly mortality on cone-bioassay indicated poor effectiveness of vector control.
Conclusions There is need to focus on low-endemic areas of kala-azar.The elimination programme should implement a routine framework for kala-azar outbreak response.Complete case-finding, use of quality-compliant insecticide and coverage of all sprayable surfaces in IRS could help interrupt transmission during outbreaks.