Human plague outbreak in two villages, Yunnan Province, China, 2005.

Plague is still a serious public health problem in Asia. On July 5, 2005, a suspected outbreak of human plague in two Chinese villages was reported to Yunnan Institute of Endemic Disease Control and Prevention (YIEDC). Active case finding, laboratory investigation, environmental inspection, and control measures were conducted by provincial and local health authorities. A suspected case was an individual who resided in one of the two villages and developed fever and painful swollen lymph nodes in the groin, axilla, and neck between June 26 and July 11, 2005. Confirmation was by indirect hemagglutination test (IHA) for plague F1 antibody. A confirmed animal plague case was an animal that tested positive for one of the following tests: IIA, reverse indirect hemagglutination, or bacterial culture. There were three confirmed and one suspected case of human plague. Of nine retrieved rats, three were confirmed cases. Most surveyed houses had poor sanitation, and there was a history of dead rats observed in the villages. After control measures were implemented, the rat density and flea index decreased to acceptable levels and no new cases occurred. The cause of this outbreak was likely due to rat die off in the villages, such that rat flea populations migrated to humans under environmentally favorable conditions. The outbreak was controlled after implementing environmental and educational control measures.

Chikungunya in Thailand: a re-emerging disease?

The first reported case of chikungunya virus diagnosed by serology in Thailand was in 1960 and the last one was in 1991. The disease surveillance system does not specifically include chikungunya cases and the signs and symptoms are similar to these of dengue fever/dengue hemorrhagic fever (DF/DHF), rubella, and fever of unknown origin (FUO); thus cases might often be reported under those diagnoses. During the rainy season of 1995 (Jun-Aug), there were at least 2 reported chikungunya outbreaks which might indicate that it is a re-emerging disease in Thailand. However, there is still limited information and knowledge on some aspects of this disease such as clinical manifestations, subclinical cases, duration of illness, complications, transmission, immunity, and reservoirs. Thus, the objectives of this paper are to describe the epidemiology of chikungunya infection based on outbreak investigations carried out in Khon Kaen (July 1991), Nakorn Si Thammarat (July 1995), and Nong Khai Provinces (August 1995). All three outbreaks occurred during the rainy season. The three most common clinical manifestations were fever with severe althralgia with maculopapular rash. Both sexes and all age groups were affected. Serological results were positive for IgM, with four-fold rises in paired sera, and viral isolation in Nakorn Si Thammarat and Nong Khai. Only in Nong Khai was hemagglutinin inhibition conducted and the results were positive. No deaths were reported. The outbreaks occurred in rural villages and all three larval indices (BI, HI, CI) were very high. The possible vectors in these outbreaks were Aedes aegypti and Aedes albopictus. In the Nong Khai outbreak, blood specimens were taken at the 3-5th day after onset and therefore the proportion of positive results was low. IgM antibody of follow-up cases declined within 3 months, villagers from all three areas with outbreaks mentioned that they had no previous experience of this disease. This suggests that chikungunya infection is a re-emerging disease.

An unusual outbreak of food poisoning.

On August 25 1990, over 400 people who attended a Thailand handicappeds' sport day at a provincial physical education college developed gastrointestinal symptoms after having dinner. An epidemiological team want to determine causes(s) and recommend how to prevent and control a food poisoning outbreak. The investigation included interviewing all 1,210 persons who attended the sport's day. In addition, an environmental survey, laboratory analysis of food samples, and rectal, ear, throat and nasal swabs from foodhandlers were also performed. A case was defined as a person who ate any items of dinner food and experienced vomiting, nausea, abdominal pain, and diarrhea. There were 485 cases out of 1,094 persons, an attack rate of 43%. Interviews were completed for 470 out of 485 cases. The three most common symptoms were nausea (93%), vomiting (88%), and abdominal pain (81.5). The mean incubation period was 3.20 hours. Three out of four items of food had a significant association with illness. Among these 3 items, eclairs had to the highest crude relative risk, 7.0 (95% CI = 4.8, 10.2). For statistical analysis, logistic regression by unconditional method was used, and found that only eclairs which were prepared during the night before the dinner and kept at room temperature for at least 12 hours before serving, remained statistically significant in the model (RR = 11.96; 95% CI = 9-22). Laboratory examination of foods and foodhandlers indicated heavy growth of Staphylococcus aureus producing toxins A and C and Bacillus cereus in eclairs. Culture of nasal swabs from healthy foodhandlers identified B. cereus and S. aureus of different phage types from those in eclairs.(ABSTRACT TRUNCATED AT 250 WORDS)