Bulletin No. 16
October 2, 1987
In late June, a resident of Emmonak was hospitalized at Bethel PHS Hospital with gastrointestinal illness caused by salmonella. This individual reported diarrheal illness in his extended family in the village. The Community Health Aide reported that 20 individuals of all ages had been seen at the health clinic during the previous two to three weeks with diarrhea.
We interviewed 54 individuals in Emmonak. Of these 54, 50 individuals met a case definition of diarrhea of at least one day's duration with onset after May 20 (Figure); 37 (74%) were female. Of the 50 cases, 18 (36%) were 0-4 years old; 9 (18%) were in the 20-24 year age group. Attack rates were highest in the 0-4 age group and the 20-24 age group. Within the 0-4 age group the attack rate for females was 31%, for males 22%. In the 20-24 age group, the attack rate for females was 22% while it was only 8% for males. Similarly in the 35-39 age group the attack rate for females was 23%; no males in this age group reported illness. Although numbers were small within groups, the two groups most affected were young children less than 4 years of age and women who were the traditional caretakers of these children.
The most prominent symptoms of these cases were diarrhea (92%), abdominal cramping (60%), chills (44%), and nausea (34%). In addition, fever (26%) and vomiting (22%) were reported. Four individuals (8%) reported bloody stool. Duration of symptoms lasted from 1-60 days with a mean of 5 days. Of the 50 cases, 30 (60%) reported diarrhea with duration of less than 4 days. Three individuals reported diarrhea greater than 14 days. Of the 50 cases, 39 (78%) reported associated illness in their family.
Of the 132 households in Emmonak, 25 (19%) reported illness. Of the 25 households, 7 reportedly had close ties through sharing meals, saunas and babysitting. Of the 50 cases, 21 (42%) were characterized as secondary household cases. The mean incubation period for these 21 secondary cases was 8 days. Of the 21 secondary cases, 13 were clustered within a week of the primary case; these may actually represent co-primary infections.
Of the 50 cases, stool samples were collected on 28 (56%). Accept for the original case of salmonella, all stool samples were negative for salmonella and shigella. Nine of the ten viral cultures were negative. A tenth viral culture on a one-year-old child was positive for coxsackie virus type B-5, isolated from the individual one month after her illness. Coxsackie B-5 is not noted for causing diarrhea.
We were unable to identify any common source of the outbreak. Affected households were scattered throughout the village, and only 25 households (19%) were affected. We do not believe this was a waterborne outbreak. City water had previously been tested and was found free of contamination.
The most likely cause of this illness in Emmonak is a virus with a person-to-person transmission. The fact that the cases were clustered every 10 days with a high secondary attack rate is consistent with transmission of a virus, either fecal-oral, respiratory, or both. The three age groups most affected were children less than 4 years of age and young women in the 20-24- and 35-39-year age groups. These three age groups accounted for 28 (56%) of all cases. Among adult cases, females were much more frequently ill than males.
(Reported by Dr. Allen Freudenthal, Bethel Hospital)
Figure 1. Gastrointestinal Illness
N = 50
|Onset by Week Ending|