General Epidemiology 2025-2026

Epidemiology BY STAFF MEMBERS F MMNITY MEDIINE DEPARTMENT EL-Minia niversity2 PREFAE It is our pleasure to present to you our books “Basi Priniples of ommunity Mediine”. We did as muh as we an in order to introdue this book in this format. We hope that this book will be benefiial as a valuable guide for our medial students. We believe that, this book an not replae the attending of letures, seminars and partiipation in the sientifi essions, and visiting the library to read the most reent journals and text books in order to maximize understanding of Basi Priniples of ommunity Mediine. ompleteness is a harater of od, so we regret for any defet in this version and we will be very grateful if you an ontat and help us to put this book in a better shape. We would liketo thank all those who ontribute in the prodution of this book. With our best wishes ontent -nal pidmilgy -Epidmilgy f sm mmniabl disass 1.disass tansmittd by dplt . disass tansmittd by ingstin 3. disass tansmittd by ntat 4. sxally tansmittd disass 5. disass tansmittd by athpd -Nn mmniabl disass 1.pidmilgy f adivasla disass .bsity 3. pidmilgy f diabts mllits 4. pidmilgy f an 5.injis and disass latd t aidnts 6. pidmilgy f smking3 General Epidemiology finitin f Halth (WH "Halth is a stat f mplt physial, mntal and sial wll-bing and nt mly th absn f disas infimity." This is nsidd an "idalisti gal" ath than a alisti n. Halth is ntal t th npt f qality f lif, and its maintnan is a ma sial invstmnt. imnsins f Halth 1. Physial imnsin Pft bilgial fntin. Evy ll and vy gan fntins at ptimm apaity and in pft hamny with th st f th bdy. . Mntal imnsin A balan btwn th individal and th snding wld. Th ability t manag thghts, mtins, and bhavis. 3. Sial imnsin Hamny and intgatin within th individal, btwn ah individal and th mmbs f sity, and btwn individals and th wld in whih thy liv. 4. Spiital imnsin Rlats t maning and pps in lif. Inlds intgity, pinipls, this, and n's pps in lif. ality f if Masmnt f halth dimnsins. It is a mas f physial, mntal, and sial wll-bing as pivd by ah individal by a gp f individals (.g., happinss, satisfatin with halth, maiag, family, wk, finanial sitatin, datinal pptnitis, t.. Sptm f Halth 1. Idal Halth mplt physial, mntal, sial, and spiital wll-bing. . Psitiv Halth A pft, ntining adjstmnt btwn th individal and th nvinmnt. 3. Ngativ Halth ik psitiv halth, bt with th slightst advs stimls, th individal will fall ill. * A. nappant (P-linial isas An appantly f psn, bt th disas an b disvd by xaminatin and sning tsts. * B. Appant isas Th individal is awa f thi illnss, whth thy sk mdial a nt. 4. ath Th nd f th halth sptm.4 tminants f halth • fats that lad t diffns in halth stats, that may latd t th individal t th snding nvinmnt and thy afft ditly inditly n th lvl f halth and th n f a disas. • 1 - Mdifiabl Fats (ntllabl .g. dit, smking stats, xis lvls. • - Nn-mdifiabl fats (nntllabl ag, sx, family histy and pdispsitin t a disas. Als an lassifid t 1- Bf bith (gnti fats, and intatin fats. - ing lab (bith injis. 3- Aft bith (ntitinal, nvinmntal and bhavial fats. Epidemiology Definition "Th stdy f th distibtin and dtminants f disas in hman pplatin." "Th stdy f th n and natal histy f all fms f disas." * It answs th qstins Whn, wh, hw, why, and wh is afftd * It lks f pattns f disas in tms f **tim, pla, and psnal haatistis. * Etymlgy *Epi* n, *dms* pplatin. Key onepts Infetion vs. Disease Inftin Th invasin f th bdy by pathgni ganisms, whih mltiply and a manifstd as inappant appant disass. isas A pathlgial nditin that intfs with nmal bdy fntin and ass impaimnt f halth. onept of Disease urrene 1-Impaimnt hangs in th individal's bdy (any lss abnmality f psyhlgial, physilgial, anatmial stt fntin. -isability Any stitin lak f ability t pfm an ativity in th mann within th ang nsidd nmal f a hman bing. 3-Handiap An impaimnt disability that limits pvnts th flfillmnt f a nmal l in th mmnity. Stages of Disease 1. P-pathgnsis (At Risk Th pid bf th nst f disas (xps t isk in nn-mmniabl disass nty f pathgn in mmniabl disass. Pimdial and pimay pvntin a applid h. . Pathgnsis/linial Stag * Bgins with th nty f an ganism int a ssptibl hst (mmniabl xps t a isk fat (nn-mmniabl. * Invlvs mltipliatin f th ganism, disas initiatin, and pgssin. * It may b -Sblinial ai N symptms (mmniabl disass. -linial Symptms (what th individal fls and Signs (what th physiian diagnss appa. Snday and ttiay pvntin a pssibl. 3. tm Stag * mplt vy (. * Rvy with maining pathlgy handiap. * ath. The Infetious yle 1. Soure of Infetion / Reservoir Th natal habitat wh an inftis agnt nmally livs and mltiplis, fm whih it an b tansmittd t a ssptibl hst. Man as Manifstd disas. ai Inftd individal witht any symptms signs wh an spad th ganism (appantly f, labaty psitiv. Animal (Zoonosis diseases) .g., gats in bllsis, attl in bvin TB, ats in txplasmsis, dgs in abis. Inanimate Reservoirs .g., plants, sil, and ingani matt (sil is th svi f histplasmsis. ai A psn animal that habs a spifi inftis agnt witht linial disas and svs as a ptntial s f inftin. ais a lss inftis than ass bt m dangs bas thy a hiddn. Typs f ais 1-Inbaty ai Inftis in th aly stags f th disas, bf symptms appa (.g., hiknpx. -nvalsnt ai ntin t shd th ganism aft ving fm an at illnss (.g., Salmnlla, Shiglla. 3-ntat ai ntats f a as wh gt inftd and liminat th inftin witht gtting disasd, bt an spad it manwhil. 4-Halthy (Asymptmati ai Rmain wll thght th inftin and nv dvlp linial symptms. lassifiatin by Pid f Inftivity hni ais Tansmit inftin f lng pids, sally v n ya (.g., Salmnlla typhi, Hpatitis B, HIV. Tansint ais F a fw days. Tmpay ais F a fw wks mnths. The important features of arriers as follows 1- Th nmb f ais may b fa gat than th nmb f ths wh a sik. (at nmb - ais a nt manifst s thy and ths a nawa that thy an tansmit th disas (inftin is nappant. 3- As ais a nt sik, thy a nt stitd and thf dissminat th disas widly (f t m. 4- hni ais may pd patd tbaks v a nsidabl pid f tim (psistnt inftivity. In baillay dysnty (shigllsis, 7 a sah f ais is gnally nsatisfaty and invstigatins shld b stitd t fd handls. In hla.. ais a f sht datin, 7% f hla ass a f f vibis at th nd f th fist wk and 8% by th nd f th thid. ng tm ais a a and f n pidmilgial imptan. In typhid th ai Stat is th mst imptant pidmilgial fat, with psistn f th ganism in sm individals f pids in xss f 5 yas. Sm ass f typhid patints a fnd t b still xting ganisms aft n ya. Ppl bm m pn t at as ais if thy hav a hni iitatin pss, sh as hlystitis and spially th psn f stns (in whih Salmnlla typhi an sviv. inay ais ftn sff fm an abnmality f th inay tat. Sh as alls and shistsma hmatbim is a pdispsing as. angs gp f ais 1- Fd handls. - Hspital psnnl (Nss – physiians. 3- Shl psnnl. 2,4 Portal of Exit/Inlet Th sit fm whih miganisms lav th svi t nt anth hst. Exampls Rspiaty tat (ns, mth, astintstinal tat (fs, Skin, Ms mmbans, inay tat, Rpdtiv tat, Bld. 3- Mode of Transmission 1- plt A-it dplt inftin Bth svi f inftin and nw hst a fnd tgth within th sam pla. Th hst gts inftd thgh dit inhalatin f dplt spay f th svi. B-Indit dplt inftin 1-Aibn inftin Ai ais ganisms in tw fms a. plt nli a mint sids f fin dplts aft vapatin f wat. Thy main sspndd in ai f hs. b. st (whih ntains sals f masls.8 - ntaminatd bts Atils (.g. ps, spns, fks and fmits (.g. lthing, handkhifs may b ntaminatd with spiaty dishags and tansmit inftin. 3- Milk ganisms in th inftd milk may invad th pp spiaty msa (nt ingstin .g. 1- Hmlyti stpti - iphthia bailli 1- Fd bn A- Ingstin f fd dinks whih ntain ganisms whih may ah fd thgh Hands, Vts, Wat, Fsh hman man and st. B- Hand t mth (fal- al - Athpd- bn inftin A- Mhanial tansmissin .g. hs flis, kahs. B- Bilgial tansmissin .g. bld sking insts 1-Msqits i - Anphls (malaia ii - lx (filaiasis, nphalitis, Rift Vally fv iii - Ads ( yllw fv, dng fv - i whih ass pidmi typhs, pidmi lapsing fv and tnh fv 3- Flas whih ass plag, min typhs, hymnlyps dimnta, diphylpthim aninm. 4- ntat Thgh ndamagd sfa Skin disass 7 Sabis, imptig njntivitis ,ptspisis Injd sfa mmn disass - B hpatitis - Syphilis - Pygni inftin 5. Suseptible Host & Immunity a- Immnity sistan f th bdy against Inftin. b- Ssptibility pnnss t ntat disas n xps t inftin Rsistan t inftin is gvnd by 1- fns mhanism Non-speifi fators Natal bais - Skin Swats, sbas stins - Rspiatin Snzing flx, gh, hai f nstil. - astintstinal tat saliva, aidity, nzyms, fla. - Ey tas Systms f immnity Speifi immunity Two main types 1. Humoral Immunity (B-lymphoyte–mediated) B lymphyts synthsiz antibdis. Antibdis at against xtallla pathgns and txins. . ell-Mediated Immunity (T-lymphoyte–mediated)9 T lymphyts (dvlp in th thyms. Rspnsibl f dfns against intallla pathgns (.g., viss, sm batia, an lls. Hst fats Whih das sistan f th bdy sh 1- nti fats (agammaglblinamia - Hmnal fats (tistids 3- Malnishmnt (das ptin intak 4- Radiatin. immunity 1- Natal aqid a- Passiv fm mth thgh mbilial d (Tans-planta milk b- Ativ - Thgh xps t inftin .Sblinial inftin (Tblsis . Manifstd disas (Masls - Atifiially indd Thgh immnizatin 1- Ative immunization 1- Vaines a - iv attnatd vain B, MMR, Sabin (PV, Inflnza, Plag (ttn's b - Killd vain TAB, hla, Ptssis, Salk, Inflnza. - Plysahaid vain bspinal mningitis d- Sfa antign vain f vis B hpatitis 2- Toxoids - iphthia - Ttans - Passive immunization (S-pphylaxis - Hman Immnglblin - Animal Antitxins as in ass f Anti ttani Sm 6-Infetious Agent/Pathogen -Miganisms (batia, viss, fngi, ptza -s f inftin - Viln Th Epidmilgi Tiangl (Elgy f isass Th fats dtmin th n f a disas thgh thi intatin Agnt, Hst, and Envinmnt. Hst Fats .g., Ag, gnd, a, si-nmi stats, patin, gnal halth stats, halth bhavi, ssptibility. Agnt Fats Nssay f th disas t . .g., Miganisms (batia, viss, fngi, ptza, s f inftin, Viln (pathgniity and svity. Envinmntal Fats Extinsi fats that afft th agnt and th hst. Physial .g., limat and ggaphy. Bilgial .g., insts that tansmit th agnt. Sinmi .g., sanitatin and wding. lassifiatin f isas an b lassifid by 1. nst. . Systm afftd. 3. Mds f tansmissin. 4. mmniability. ommuniable Disease An illnss d t a spifi inftis agnt its txi pdts, aising thgh tansmissin fm a svi t a ssptibl hst, ith ditly inditly. Mds f Tansmissin plt, ingstin, ntat, sxally, athpd, bld , vtial A. Droplet Infetion Hst gts inftd by inhaling dplts xplld fm th svi's spiaty tat. A-it plt InftinRsvi and hst a tgth in th sam pla. Hst inhals dplts ditly. B-Indit plt Inftin Rsvi and hst a nt tgth. Hst inhals indit dplt spay. 1. Aibn Inftin Ai ais ganisms as a. plt nli Mint sids f vapatd dplts that main sspndd in ai f hs. b. st id spiaty dishags that an bm aibn again. . ntaminatd bts Atils (ps, spns and fmits (lthing, handkhifs. 3. Milk ganisms in inftd milk invad th pp spiaty msa (.g., Hmlyti stpti, iphthia bailli.