Dengue haemorrhagic fever outbreak in Karachi, Pakistan, 1994

Multiple dengue serotypes and high frequency of dengue hemorrhagic fever at two tertiary care hospitals in Lahore during the 2008 dengue virus outbreak in Punjab, Pakistan

OBJECTIVE

The objective of this study was to investigate the clinical characteristics of patients with dengue viral infection during the 2008 outbreak in Lahore in order to better understand the clinical pattern and severity of disease in Lahore.

METHODS

We analyzed the clinical characteristics of 110 patients infected with dengue virus; data were collected on standardized data collection sheets at two tertiary care hospitals from September to December 2008. Dengue infection was confirmed serologically or by real-time polymerase chain reaction (RT-PCR).

RESULTS

Out of the total of 110 dengue infected patients, 70 were male and 40 were female. The most common symptoms included fever (100%), myalgia (68.2%), headache (55.5%), nausea (39.1%), skin rash (53.6%), mucocutaneous hemorrhagic manifestations (58.2%), and ocular pain (20%). Classic dengue fever (DF) was seen in 41.8% of the patients, 56.4% had dengue hemorrhagic fever (DHF), and only 1.8% developed dengue shock syndrome (DSS). The mean duration of fever was 6 days. Thrombocytopenia, leukopenia, and abnormal aspartate aminotransferase (AST)/alanine aminotransferase (ALT) were more frequently encountered in DHF and DSS as compared to DF. Viral RNA detection was done by RT-PCR in 17 patients. Ten patients had DEN4, five had DEN2, and two had DEN3 serotypes. The majority of the patients recovered completely without complications.

CONCLUSION

The high frequency of DHF during the 2008 outbreak and the presence of three different dengue serotypes, emphasize the need to prevent and control dengue infection. Health authorities should consider strengthening surveillance for dengue infection, given the potential for future outbreaks with increased severity. It is also suggested that primary care physicians should be educated regarding recognition of DHF and to identify patients at high risk of developing DHF and DSS.

Severe dengue epidemics in Sri Lanka, 2003-2006

One-sentence summary for table of contents: Changes in transmission dynamics and virus genes are likely increasing emergence of severe epidemics in this country.

Recent emergence of dengue hemorrhagic fever in the Indian subcontinent has been well documented in Sri Lanka. We compare recent (2003–2006) and past (1980–1997) dengue surveillance data for Sri Lanka. The 4 dengue virus (DENV) serotypes have been cocirculating in Sri Lanka for >30 years. Over this period, a new genotype of DENV-1 has replaced an old genotype. Moreover, new clades of DENV-3 genotype III viruses have replaced older clades. Emergence of new clades of DENV-3 in 1989 and 2000 coincided with abrupt increases in the number of reported dengue cases, implicating this serotype in severe epidemics. In 1980–1997, most reported dengue cases were in children. Recent epidemics have been characterized by many cases in children and adults. Changes in local transmission dynamics and genetic changes in DENV-3 are likely increasing emergence of severe dengue epidemics in Sri Lanka.

Co-circulations of two genotypes of dengue virus in 2006 out-break of dengue hemorrhagic fever in Karachi, Pakistan

BACKGROUND

The status of dengue genotypes involved in the recent epidemic out-breaks in Pakistan is not well defined.

OBJECTIVES

We sought to analyze the predominant genotype responsible for the most severe and largest out-break of dengue hemorrhagic fever (DHF) that hit Karachi in 2006.

STUDY DESIGN

Retrospective analysis of stored serum samples for dengue virus genotype by multiplex RT-PCR, anti-dengue IgM, IgG and review of clinical charts of patients admitted to Aga Khan University Hospital.

RESULTS

Viral RNA detection of 250 patients revealed positive results in 185 (74.0%) samples. DEN-2 was predominant genotype (n=104, 56.2%) Dengue specific antibodies were detected in 139 samples of which 81 were classified as primary cases. DEN-2 accounted for these. Within secondary cases, 63.2% were due to DEN-2 (total 57), the rest were positive for DEN-3. DHF (p=0.064) and abdominal pain (p=0.059) were more frequently associated with DEN-2 as compared to DEN-3. None of the samples were positive for DEN-1 or DEN-4.

CONCLUSION

Co-circulation of DEN-2 and DEN-3 was responsible for the 2006 out-break in Karachi. Primary and secondary cases were seen in both groups. Cases with DHF showed marginal association with DEN-2. Introduction of a new serotype (DEN-3) and or a genotypic shift of endemic serotype (DEN-2) are the probable factors for the recent out-break of DHF in this region.

Dengue outbreak in Karachi, Pakistan, 2006: experience at a tertiary care center

This is the first report of the largest epidemic of dengue hemorrhagic fever (DHF) virus infection (2006) with IgM-confirmed cases from Karachi, Pakistan. Medical records of 172 IgM-positive patients were reviewed retrospectively for demographic, clinical and laboratory data. Patients were categorized into dengue fever (DF) and DHF according to the WHO severity grading scale. The mean+/-SD age of the patients was 25.9+/-12.8 years, 55.8% were males and the hemoconcentration was recorded in a small number of patients [10 (7.0%)]. Male gender [odds ratio (OR)=14.7, P=0.003), positive history of vomiting (OR=4.3, P=0.047), thrombocytopenia at presentation (OR=225.2, P<0.001) and monocytosis (OR=5.8, P=0.030) were independently associated with DHF, but not with DF. Five cases (2.9%) had a fatal outcome, with a male-to-female ratio of 1:4. Three were from a pediatric group (<15 years). Pulmonary hemorrhages, disseminated intravascular coagulation and cerebral edema preceded death in these patients. The results have highlighted significant findings, such as adult susceptibility to DHF, pronounced abdominal symptoms and lack of hemoconcentration at time of presentation in the study population. These findings may play an important role in the case definitions of future studies from this part of the world.

Dengue virus infection among children with undifferentiated fever in Karachi

Sera were collected from a total of 122 children, comprising 117 cases with undifferentiated fever and 5 cases with dengue hemorrhagic fever (DHF), during June to September 1994 in Karachi, Pakistan. Sera were tested by the IgM-capture ELISA using dengue type 1 (D1), dengue type 2 (D2), West Nile (WN), and Japanese encephalitis (JE) viral antigens. Among 92 single sera from undifferentiated fever cases, IgM antibodies were detected in 5 cases by D1, 8 cases by D2, and 5 cases by WN antigens, respectively. Corresponding number of positives among 25 paired sera from undifferentiated fever cases were 3 by D1, 6 by D2, and 1 by WN antigen. Four out of 5 DHF cases possessed anti-D1 as well as anti-D2 IgM antibodies. Only a single DHF case was positive for anti-WN IgM antibodies. Anti-JE IgM antibodies were not detected in any of the tested serum specimens. Clinical manifestations of undifferentiated fever patients were generally non specific, but the percentage of children with anemia, hepatomegaly and splenomegaly was higher in patients possessing anti-dengue IgM antibodies than those without. Among the groups with anti-dengue IgM antibodies, those possessing only anti-D2 but not anti-D1 IgM antibodies showed higher percentages with cough, edema, and splenomegaly. The results indicated that up to 26% of the undifferentiated fever cases were caused by dengue virus infection in Karachi, Pakistan.

Expansion of epidemic dengue viral infections to Pakistan

OBJECTIVES

Antibodies to dengue viruses have occasionally been reported in individuals in Pakistan, but the frequency of occurrence of dengue infection in Pakistan is unclear. The first confirmed dengue hemorrhagic fever outbreak in Pakistan occurred in 1994. In October 1995, the authors investigated an outbreak of a febrile illness among employees of a construction contractor at a power generation plant in Baluchistan, Pakistan, to determine the cause of illness and recommend appropriate preventive measures.

METHODS

The work site and living arrangements were inspected, a questionnaire was administered, and serum samples were collected from all consenting contractor employees and their families if they lived at the camp. Sera were analyzed for IgM against dengue virus, using an enzyme-linked immunosorbent assay.

RESULTS

Interviews were conducted with 76 persons (mean age, 42y); 95% were men. Forty-two persons (55%) reported having experienced fever, headache, or myalgia in the preceding 6 weeks. Fifty-seven subjects (75%) had IgM antibodies against at least one dengue serotype; 45 subjects (59%) had IgM antibodies against dengue serotype 2.

CONCLUSION

This was an outbreak of dengue fever due to multiple serotypes of dengue virus. This confirms that epidemic dengue infection was present in southern Pakistan for 2 consecutive years.

Involvement of the central nervous system in dengue fever: three serologically confirmed cases from Fortaleza Ceará, Brazil

Three cases of dengue fever involving the central nervous system (CNS) are reported. All occurred in 1994 during a dengue (DEN) epidemic caused by serotypes DEN-1 and DEN-2. The first case examined was a 17-year-old girl who complained of fever, nuchal rigidity and genital bleeding. Three blood samples were positive by anti-dengue IgM ELISA and showed hemagglutination-inhibition (HI) test titers > or = 1,280. The second case concerned a 86-year-old women with fever, muscle and joint pains, altered consciousness, syncope, nuchal rigidity and meningismus. Her blood sample showed an HI titer of 1:320 for flaviviruses, and an IgM ELISA positive for dengue. The third case was a 67-year-old women with fever, abnormal behaviour, seizures, tremor of extremities, thrombocytopenia, increased hematocrit and leukopenia. The patient suffered a typical case of dengue hemorrhagic fever with ensuing shock and a fatal outcome. A single blood sample showed HI antibodies of > or = 1,280 and an IgM ELISA positive for dengue. No virus could be isolated from any patient by inoculation of blood into C6/36 cells and suckling mice. No other agent of disease was encountered in the patient.