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Background Measles is a highly contagious and a vaccine-preventable disease. On 14 August 2015, a measles outbreak was reported in Langkat District, North Sumatra province of Indonesia. To investigate the risk factors of the outbreak and to recommend control measures, an epidemiological investigation was undertaken. Method A 1:1 matched case-control study was conducted. All suspect and confirmed cases were recruited and included. Controls were healthy neighbors of cases, matched for age and gender. House-to-house search for cases was carried out. Structural interviews were conducted to solicit demographic data, clinical data, as well as the risk factors. A two-step logistic regression was employed to assess the potential risk factors associated with the infection. Results During 20 July to 25 September 2015, a total of 28 measles cases were identified with no death. All tested blood samples were positive for measles-specific IgM antibodies confirming the outbreak. All cases presented with fever and rash; cough (80%), coryza (65%), and conjunctivitis (25%). The attack rate (AR) was 14.1% (age ranged between 1 and 14 years old), the highest AR (50.0%) occurred among those aged 1–4 years. In multivariate model, those who have not received measless vaccication and those who had contact with a measles case had higher odds of having infection, with adjusted odds ratio (aOR): 2.31 (95%CI: 1.22–4.27) and aOR: 1.15 (95%CI: 1.12–3.70), respectively. Conclusions Being unvaccinated and having a contact history increased the risk of measles are two risk factors of measles infection. A mass measles immunization to the school children was undertaken and a strict measles surveillance and notification system were recommended to control the transmission in the future.

Dengue fever (DF) infection continues to present a seriuos public health problem in North Sumatera, Indonesia. A DF outbreak was reported in Merek Sub-district, Karo District which is one tourist destination in North Sumatera during April-May 2017. An epidemiological investigation was conducted to identify the risk factors and recommend control measures. An observational study with a matched case control design was conducted. A case was defined as any resident of Merek sub-district who had suffer major clinical symptoms of DF such as fever, severe headache, pain behind eyes, muscle and joint pains, and rash from April – May, 2017. A control was defined as neighbors of cases who did not have clinical signs and symptoms of DF and were matched for age and sex. We interviewed 37 cases and 37 controls. Age cases ranged from 2 year to 37 years (median= 12 years). The multivariate analyses showed that presence of mosquito breeding sites (OR=4.87, 95%CI=1.33-17.85) and habit of hanging worn clothes (OR=5.12, 95%CI=1.25-21.03) were significant risk factors. It is recommended to eliminate mosquito breeding sites routinely, avoid habit of hanging worn clothes, and conduct strict surveillance of DF continously.

Background: Chikungunya is a serious emerging arbovirus in Indonesia. On 12 October 2013, an outbreak of chikungunya was reported in Serdang Bedagai District, North Sumatera, Indonesia. Objective: An epidemiological investigation was conducted to identify the risk factors for the outbreak and recommend control measures. Method: A 1:1 matched case-control study was conducted. A case of chikungunya was defined as a previously well resident of Sei Suka Subdistrict who had clinical symptoms of chikungunya fever such as fever, arthralgia, myalgia, rash and headache of at least two days duration between 8 August and 17 November 2013. Cases were identified by active case finding through the affected area; a control was defined as a neighbor of a case that did not have clinical signs and symptoms of chikungunya, matched for age and gender. Blood samples were tested using ELISA assay to confirm the presence of anti-CHIKV specific IgM antibody. Results: Total of 94 cases and 94 controls were included in the case control study. Age ranged from 1 year to 76 years (median 35 years) and 57% were female. In multivariate analyses, being a household contact of a chikungunya case (adjusted OR=11.4, 95%CI=4.69-27.55) and lack of routinely eliminating mosquito breeding sites were risk factors (adjusted OR=3.3, 95%CI=1.50-7.05). Six out of ten cases were positive for CHIKV IgM antibody. Conclusions: In this confirmed outbreak of chikungunya, using anti mosquito measures were protective, reinforcing the need for routine elimination of mosquito breeding sites as well as control measures in affected households and communities.

Background Chikungunya fever is a vector-borne disease with high morbidity rates, prolonged polyarthritis in some cases and it cause substantial socioeconomic impact. On 4 January 2010, an outbreak of Chikungunya fever was reported in West Borneo in Indonesia. The total number of cases was 65 with no fatalities. An analytical study was undertaken to determine the risk factors for the outbreak. Method This was an observational study with case control design. Cases were those with major clinical symptoms of Chikungunya fever, such as fever, arthalgia, myalgia, rash and headache. Controls were neighbours of cases who did not have clinical symptoms of the disease. The study used bivariate and multivariate analyses with χ 2 and logistic regression. OR was used to determine risk factors. Some patient9s blood was tested to confirm the diagnosis. Results From the bivariate analyses, risk factors were farming in the forest (p value Conclusions Farming in the forest was a risk factor for infection. This was the basis for health promotion and prevention of future cases of Chikungunya fever in West Borneo.