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in february 1994 , we investigated a cluster of 5 plague cases in goriat , a town of 50,000 persons in a remote desert area in northwestern saudi arabia . on february 18
, a 26 year - old - woman was admitted to the provincial hospital for severe pharyngitis and tonsillitis . given the striking swelling of her neck , local clinicians suspected diphtheria . since 2 of the patient 's relatives
had also been hospitalized in the previous 2 days with similar illnesses , the hospital called for assistance from the local preventive medicine specialist . he had seen similar cases in 1984 and suspected pharyngeal plague . through interviews with physicians and review of hospital admissions , we identified 5 patients , including the index case , who had been hospitalized with suspected plague or plague pharyngitis .
the patients included a 9-year - old girl and 4 adults ( 2 men and 2 women , age range 1835 years ) .
symptoms developed in 1 patient on february 15 and in 4 patients on february 16 .
all had fever ( 39c40c ) , chills , malaise , myalgias , vomiting , headache , and delirium .
four had severe pharyngitis ; 3 of them had dysphagia , tender submandibular lymphadenitis , and tonsillar enlargement .
the fourth patient , the 9-year - old girl , had severe abdominal pain and tenderness on abdominal palpation , profound hypotension ( blood pressure 60/30 mm hg ) , and a generalized hemorrhagic rash .
this patient and the 26-year - old index patient ( blood pressure 90/60 mm hg ) died .
these 4 patients with pharyngitis did not have buboes or lymphadenitis at any other site .
the patient without pharyngitis had axillary lymphadenitis and cellulitis of his right arm ; he had cut his arm while killing a sick camel on february 13 .
y. pestis was isolated from the blood of the patient with pharyngitis who died and from the spinal fluid of the patient with abdominal pain .
indirect hemagglutination for plague was positive in convalescent - phase sera from the 3 survivors from whom y. pestis was not isolated .
the patients were from 4 related families , 2 from goriat and 2 from a village 20 km from this town .
the adult family members denied seeing rodents around their homes or being bitten by fleas or other biting insects .
the male head of each family traveled to the desert daily to allow his camels to graze .
we observed 3 camel carcasses in the desert near a corral where the camels were fed grain and hay to supplement their grazing .
the meat from the sick camel that had been butchered on february 13 was shared among 11 families ( 106 members ) .
the 4 patients with pharyngeal plague were among 37 people who had eaten this camel meat ; 1 patient with bubonic plague ( the man who slaughtered the camel ) was among the 69 people who had not eaten the meat ( risk ratio [ rr ] 7.7 , p<0.05 , fisher exact test ) . moreover , pharyngeal plague developed in 4 of 6 patients who had eaten raw camel liver , but not in 31 persons who had eaten only cooked camel meat or liver ( rr not defined , p<0.01 , fisher exact test ) .
we isolated y. pestis from a sample of leftover camel meat containing bone and marrow .
jirds ( meriones libycus ) , jird carcasses , rodent burrows , and rodent excreta were found at the camel corral .
y. pestis was isolated from the blood and liver of live jirds collected from the camel corral and from fleas ( xenopsylla cheopis ) combed from these jirds .
this investigation confirms that human plague with pharyngeal and gastrointestinal symptoms can result from eating infected raw camel liver .
only 1 published report has proposed this method of infection . in 1976 , in a small , remote libyan village , 13 plague cases occurred after a sick camel was slaughtered and its meat eaten ( 4 ) .
however , as a source of infection eating camel meat could not be distinguished from droplet transmission , percutaneous exposure during camel killing or handling fresh meat , or flea bites .
moreover , plague infection was not found in the camel , and the human pharyngeal plague might have resulted from crushing fleas between the teeth while grooming ( 5 ) .
the 4 patients with pharyngeal plague had symptoms similar to those of domestic cats with plague in new mexico , where 46% of plague - infected cats had submandibular lymphadenitis ( 2 ) .
similarly , since human plague patients had submandibular lymphadenitis , tonsillitis , pharyngitis and dysphagia , or severe gastrointestinal symptoms , this suggests ingestion as the route of exposure .
christie et al . suggested that among domestic animals , camels may be an important plague host because their wide - ranging behavior increases the chance of coming into contact with natural plague foci ( 4 ) .
our investigation indicates another scenario , with evidence of a plague epizootic at a fixed site where camels were corralled .
russian investigators have proposed several methods of natural infection of camels : bites from rodent fleas , mechanical transmission from ticks , eating feed contaminated with excreta of infected rodents , and eating dead rodents along with their feed ( 6 ) .
this unusual profile of human plague was recognized because several related patients with life - threatening illnesses were seen at a hospital over a 2-day period and a medical officer recognized the illness .
sporadic cases of pharyngeal or gastrointestinal plague would be less likely to attract the attention of medical or public health workers .
clinicians and public health officers , particularly in the middle east , north africa , and central asia , should be alert for sporadic cases of pharyngeal or gastrointestinal plague so that curative and preventive measures can be promptly initiated .
we investigated a cluster of 5 plague cases ; the patients included 4 with severe pharyngitis and submandibular lymphadenitis . these 4 case - patients had eaten raw camel liver . 
 yersinia pestis was isolated from bone marrow of the camel and from jirds ( meriones libycus ) and fleas ( xenopsylla cheopis ) captured at the camel corral .