2003 Monaca outbreak The largest outbreak of hepatitis A virus in United States history occurred among people who ate at a now-defunct Mexican food restaurant located in Monaca, Pennsylvania in late 2003. Over 550 people who visited the restaurant between September and October 2003 were infected with the virus, three of whom died as a direct result. The outbreak was brought to the attention of health officials when local emergency medicine physicians noticed a significant increase in cases of hepatitis A in the county. After conducting its investigation, the CDC attributed the source of the outbreak to the use of contaminated raw green onion. The restaurant was purchasing its green onion stock from farms in Mexico at the time. It is believed that the green onions may have been contaminated through the use of contaminated water for crop irrigation, rinsing, or icing or by handling of the vegetables by infected people. Green onion had caused similar outbreaks of hepatitis A in the southern United States prior to this, but not to the same magnitude. The CDC believes that the restaurant's use of a large communal bucket for chopped raw green onion allowed non-contaminated plants to be mixed with contaminated ones, increasing the number of vectors of infection and amplifying the outbreak. The restaurant was closed once it was discovered to be the source, and over 9,000 people were given hepatitis A immune globulin because they had either eaten at the restaurant or had been in close contact with someone who had.
2003 MonAca OuTbreak the LaRgesT oUtbreAk of hepatItiS a virus in UNitEd stAtes hiSToRy OcCURred aMOng PeoPLE wHo ate At A now-defunCt mExican fooD ReStaurant loCAted In mOnaca, pennsYlVania IN latE 2003. oVEr 550 people wHo VIsiteD THe RestauRaNt bEtwEEn SepteMber aND oCtObEr 2003 wErE infecteD with the virUs, THREe of whom dieD As a DirEct rEsULt. the oUtBrEak was brought to the ATTenTIOn Of hEALTH oFFiCIals When locAl EmERgeNCy medicinE PhysIciaNS notICEd a SignifiCant iNcrease IN cases Of hEpatITis a iN ThE cOunty. after CONDUCtiNg its iNvestiGation, tHe cdC aTTrIButEd the souRce Of THe outBrEaK to The use of contaMinaTEd rAw gReen onioN. the rEStaurant was purcHaSing its greEn OniOn sTock from farmS in mexico At the TIme. It is belIEvEd that thE Green Onions MAY hAVe beeN coNTaMinated tHrouGh ThE use of cONtaminatED waTeR fOr CrOp irRigation, rinSINg, or IciNg or By Handling oF tHe vEGetabLes by infeCted People. gREen Onion had cAUsed sImILaR OUtbreaks Of HepaTItis a In ThE sOuTHern uNiTeD States prior TO ThIs, BUT nOt tO the Same magnITude. ThE cdC bELieves ThaT the resTauranT's Use Of a LaRGE comMUNal BUckeT For chopped RaW gReeN OnIoN alloweD NoN-CoNtAminaTed plaNTS to be mixeD with cOntAminATEd Ones, IncrEAsiNg the numBeR of VECTorS of infectiOn and amplifyING The OuTbrEaK. the Restaurant was cLosed oNCe it was disCoverEd to be tHE SoURCe, and ovEr 9,000 PeOple Were gIven hepatitiS a iMmune gLoBulin because they HaD eiThEr EATEN at the ReStaurant or haD Been in close cOnTAct with SOmeOne WHo had.