Transmission of cholera is through -

Ans. is 'd' i.e., All of the above Cholerao Cholera is caused by a gram-negative toxin (enterotoxin) producing bacteria, vibrio cholerae. Cholera toxin acts through cAMP in the intestine to cause secretory diarrhea,o V. cholerae causing infections are divided into two biotypes :ClassicalEl Toro Both of which are further subdivided into three serotypes :i) Ogawaii) Inabaiii) Hikojimao Ogawa serotype of E-l Tor biotype is the most common one in India. But according the recent reports, El Tot- Hybrid subtype has become the most common subtype in India,o Man is the only reservoir. The immediate source of infection are the stools and vomits of cases and carrier. Infection is acquired through fecalty contaminated water or food. Chlorination of water is effective against V. cholerae.o The continuous transmission, involving mild and asymptomatic cases, is the most important mechanism in sustaining cholera during inter-epidemic period.o Most susceptible blood group to cholera is 'O' followed by B>A>AB.o There are following tyes of carrier in cholera.Incubatory : Shed vibrios only in the brief incubation period of 1-5 days.Convalescent: Shed vibrios for 2-3 weeks.Healthy or contact carrier : Has had subclinical infection and shed vibrios for less than 10 days.Chronic carriers : Can shed vibrios for months or years and may have persistent infection in gall bladder.