br Introduction Sickle cell disease SCD
Introduction Sickle-cell disease (SCD) is considered a major global public health problem (Serjeant, 2014). There are approximately 250,000 births annually (Hannemann et al., 2011). Africa, bears the highest burden of the disease (Makani et al., 2013). However many cases occur in the United States of America, the Caribbean, and Northern Europe (Hannemann et al., 2011). In Jamaica the β-globin chain abnormalities βS and βC occur with gene frequencies of 0.055 and 0.019 respectively (Serjeant, 1981). Differences in the characteristics of haemoglobin C and S have been reported, including distinctly more noticeable K+ loss and dehydration in haemoglobin SC red Purmorphamine Supplier and this contributes to differences in the phenotypic manifestations between haemoglobin SC disease (HbSC) disease and homozygous haemoglobin SS (HbSS) disease (Hannemann et al., 2011). However whether there are phenotypic differences in response to dengue fever between the genotypes is unclear. In Jamaica, the Sickle Cell Unit (SCU) is the only comprehensive care facility that provides care for SCD with more than 5000 individuals registered at the facility. Many countries with a high SCD burden are also known to have outbreaks of dengue fever (DF) which is a mosquito borne, viral illness (Brown et al., 2009). In fact, like SCD, dengue fever is also a major public health concern (Limonta et al., 2009) and is endemic in at least 100 countries in Asia, the Pacific, the Americas, Africa, and the Caribbean. It is said that more than one-third of the world\'s population live in these high risk areas. In the tropics and subtropics, DF is a leading cause of death (Centers for Disease Control and Prevention, 2013). The World Health Organization (WHO) estimates that 50 to 100 million dengue infections occur yearly, including 500,000 cases of dengue hemorrhagic fever (DHF) and 22,000 deaths annually, mostly among children and during the last 50years, the incidence has increased 30-fold (World Health Organization, 2014). Indeed, there have been widespread epidemics of DF in Caribbean countries including Cuba and Jamaica. The two most recent outbreaks in Jamaica were in 2010 and 2012, where 3202 and 5903 suspected cases were reported, respectively (National Surveillance Unit, Ministry of Health, Jamaica). In Jamaica, DF is a class 1 reportable disease (Ministry of Health Kingston Jamaica, 2012). According to Sickle Cell Unit clinic guidelines, DF is suspected in persons with SCD if the patient presents with a fever and two or more of the following symptoms: headache, retro-orbital pain, myalgia, arthralgia or rash (Asnani et al., 2008). Patients were either treated as outpatients or admitted to hospital depending on their clinical condition. During epidemics, individual patients suspected of having DF are not always specifically tested but in keeping with Ministry of Health reporting guidelines, are designated as likely cases based on clinical criteria.
Materials and Methods
Results During the study period, January 1, 2010 to December 31, 2012, 111 patients with either HbSC or HbSS disease registered at the SCU were suspected of having DF. Of these 40 subjects (36.0%) had definitive serological evidence of current dengue fever (Confirmed DF) and comprised the analytical sample. Twenty-seven subjects (24.3%) had serology that was not in keeping with dengue fever (Unlikely DF), while 44 subjects (39.6%) had serological data that was either equivocal or unavailable (Possible DF) (Fig. 1).
Discussion In this study we sought to determine the mortality experience of persons with HbSS and HbSC with laboratory confirmed dengue, as well as to ascertain whether there were differences in morbidity. Our findings of a thirty fold increased mortality among persons with SCD, is supported by previous reports mainly from Cuba, which have suggested that SCD is a risk factor for severe DF. Bravo et al. (1987), reporting on the 1981 Cuban epidemic, stated that chronic diseases such as bronchial asthma, diabetes mellitus and sickle cell anaemia (Hb SS disease) were risk factors for severe disease. Limonta et al. (2009) reported two persons who died in the 2001–2002 Havana dengue epidemics, both with SCD. The genotypes of the affected persons were however not stated. Moesker et al. (2013) reported two cases from Curacao of fatal DF in persons with SCD (one case had Hb SC disease, the other Hb SS disease).