Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

David Alan Janssen, M.D.

Infectious Disease Physician in O Fallon, MO · enumerated 2006.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1700995339

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Registry record

Entity type Individual (Type 1)

Name David Alan Janssen

Credential M.D.

Sex Male

Practice address 20 Progress Point Pkwy Ste 206, O Fallon, MO, 63368

Phone (636) 344-2014

Fax (314) 747-1476

Enumeration date Aug 29, 2006

Last updated in NPPES Oct 21, 2025

Taxonomy & licenses

207RI0200X Infectious Disease Physician Allopathic & Osteopathic Physicians · License 208810309 (MO) Primary

174400000X Specialist Other Service Providers · License 103905 (MO) Secondary

207RI0200X Infectious Disease Physician Allopathic & Osteopathic Physicians · License 036176531 (IL) Secondary

MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

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Frequently asked questions

Where does David Janssen practice?

The practice location on file with NPPES is in O Fallon, MO. Providers can have multiple locations; NPPES lists the primary practice address.

What is the NPI number for David Janssen?

The National Provider Identifier (NPI) for David Janssen is 1700995339, a Type 1 (individual) record in the CMS NPPES registry.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2025-10-21.