Evidence for chikungunya and dengue transmission in Quelimane, Mozambique: Results from an investigation of a potential outbreak of chikungunya virus.

BACKGROUND: In January 2016, health authorities from Zambézia province, Mozambique reported the detection of some patients presenting with fever, arthralgia, and a positive result for chikungunya in an IgM-based Rapid Diagnostic Test (RDT). We initiated a study to investigate a potential chikungunya outbreak in the city of Quelimane. METHODS/PRINCIPAL FINDINGS: From February to June 2016, we conducted a cross-sectional study enrolling febrile patients attending five outpatient health units in Quelimane. Serum from each patient was tested for CHIKV and DENV, using IgM and IgG ELISA and qRT-PCR. Patients were also tested for malaria by RDT. Entomological surveys were performed around patients' households, and we calculated the proportion of positive ovitraps and the egg density per trap. A total of 163 patients were recruited, of which 99 (60.7%) were female. The median age was 28 years. IgM and IgG anti-CHIKV antibodies were identified in 17 (10.4%) and 103 (63.2%) patients, respectively. Plaque reduction neutralization assay confirmed the presence of anti-CHIKV antibodies in a subset of 11 tested patients with positive IgG results. IgM anti-DENV antibodies were found in 1 (0.9%) of 104 tested patients. Malaria was diagnosed in 35 (21.5%) patients, 2 of whom were also IgM-positive for CHIKV. Older age and lower education level were independently associated with the prevalence of IgG anti-CHIKV antibodies. Immature forms of Aedes aegypti were collected in 16 (20.3%) of 79 surveyed households. We also found that 25.0% (16/64) of the traps were positive, with an average of 90.8 eggs per pallet. CONCLUSIONS: Our investigation demonstrated that no CHIKV outbreak was ongoing in Quelimane; rather, endemic transmission of the virus has been ongoing. Aedes aegypti mosquitoes are abundant, but dengue cases occurred only sporadically. Further population-based cohort studies are needed to improve our understanding of aspects related to the dynamics of arboviral transmission in Mozambique, as well as in other parts of Sub-Saharan Africa.

Evidence for chikungunya and dengue transmission in Quelimane, Mozambique: Results from an investigation of a potential outbreak of chikungunya virus

Background: In January 2016, health authorities from Zambézia province, Mozambique reported the detection of some patients presenting with fever, arthralgia, and a positive result for chikungunya in an IgM-based Rapid Diagnostic Test (RDT). We initiated a study to investigate a potential chikungunya outbreak in the city of Quelimane. Methods/principal findings: From February to June 2016, we conducted a cross-sectional study enrolling febrile patients attending five outpatient health units in Quelimane. Serum from each patient was tested for CHIKV and DENV, using IgM and IgG ELISA and qRT-PCR. Patients were also tested for malaria by RDT. Entomological surveys were performed around patients' households, and we calculated the proportion of positive ovitraps and the egg density per trap. A total of 163 patients were recruited, of which 99 (60.7%) were female. The median age was 28 years. IgM and IgG anti-CHIKV antibodies were identified in 17 (10.4%) and 103 (63.2%) patients, respectively. Plaque reduction neutralization assay confirmed the presence of anti-CHIKV antibodies in a subset of 11 tested patients with positive IgG results. IgM anti-DENV antibodies were found in 1 (0.9%) of 104 tested patients. Malaria was diagnosed in 35 (21.5%) patients, 2 of whom were also IgM-positive for CHIKV. Older age and lower education level were independently associated with the prevalence of IgG anti-CHIKV antibodies. Immature forms of Aedes aegypti were collected in 16 (20.3%) of 79 surveyed households. We also found that 25.0% (16/64) of the traps were positive, with an average of 90.8 eggs per pallet. Conclusions: Our investigation demonstrated that no CHIKV outbreak was ongoing in Quelimane; rather, endemic transmission of the virus has been ongoing. Aedes aegypti mosquitoes are abundant, but dengue cases occurred only sporadically. Further population-based cohort studies are needed to improve our understanding of aspects related to the dynamics of arboviral transmission in Mozambique, as well as in other parts of Sub-Saharan Africa.

A historic report of zika in mozambique: implications for assessing current risk

Although Kokernot et al. found neutralizing antibodies against ZIKV in Mozambique in 1957 [20], the country has repeatedly been excluded from the list of countries with a past history of ZIKV. The current Centers for Disease Control and Prevention map, the recent World Health Organization Risk Assessment map on ZIKV in the Africa region, and most of the recent literature mapping countries with a current and past history of ZIKV have consistently excluded Mozambique [10, 21, 22] from the list of countries with past serological evidence of ZIKV. This might result in errors in the calculation and interpretation of the risk of Zika in Mozambique as well as in the region. In this regard, in this manuscript we revisit findings of the study conducted by Kokernot et al. in an attempt to discuss the current risk of Zika in the country. The survey, conducted in 1957, was published in Portuguese in 1960 [20]. This study was part of a larger study on arboviruses, in which blood samples were screened for antibodies against 13 arboviruses, including ZIKV, chikungunya, Rift Valley fever, Sindbis, Middleburg, and Wesselsbron. Samples were collected in 29 localities situated widely apart from each other throughout the country between July and August 1957. In each locality, they selected an average of 30 local residents who had been born in the area with no history of travel outside in their lifetime. The samples were analyzed in South Africa, using confirmatory neutralization testing (NT). NT was performed using an in vivo system. For this purpose, previously titrated virus strains for each arbovirus being tested were incubated with each participant's serum and inoculated into Swiss mice to assess the neutralization profile of each serum against each virus strain. For ZIKV, the prototype ZIKV strain was used [18], and both adult and newborn mice were used for inoculation. An amount of 0.03 mL of the preparation virus and serum was inoculated intracerebrally, as previously described [18], and each mouse was observed daily between 10­ 17 days to assess the viral effect. The authors found neutralizing antibodies to all of the viruses and concluded that the whole length of Mozambique was a "tropical corridor" of arbovirus activity. The viruses with highest prevalence rates of neutralizing antibodies were chikungunya (21.0%), Wesselsbron (15.9%), Bunyamwera (24.1%), Pongola (23.2%) and Bwamba fever (24.7%)...

Caracterização genética dos vírus do sarampo genótipo D4 detectados no Brasil no período de 2003-2012 / Genetic characterisation of measles virus genotype D4 detected in Brazil, 2003-2012

O sarampo é uma doença exantemática viral, altamente infecciosa, causada por um vírus da família Paramyxoviridae, gênero Morbillivirus que, apesar de estar disponível uma vacina, segura e eficaz contra a doença, esta ainda constitui uma importante causa de morbidade e mortalidade infantil em muitos países em desenvolvimento. Embora exista apenas um tipo antigênico do vírus do sarampo, estudos de caracterização genética dos vírus de tipo selvagem permitiram a identificação oito subtipos (A-H) e 24 genótipos. O Brasil eliminou a transmissão autóctone do vírus do sarampo a partir do ano 2000. A partir de então foram confirmados vários casos de sarampo importados ou relacionados a importações, principalmente do genótipo D4. A epidemiologia molecular dos vírus do sarampo baseada nas análises da região C-terminal da nucleoproteína tem demonstrado uma diversidade limitada entre as cepas circulantes, dificultando dessa forma a determinação da origem dos vírus usando apenas essa região. O objetivo deste trabalho foi caracterizar geneticamente os genótipos D4 dos vírus do sarampo detectados no Brasil no período de 2003 a 2012, e para tal, as sequências da proteína H completa e do gene N parcial foram analisadas. Os casos positivos para o genótipo D4 foram previamente identificados pela amplificação dos 450nt da região C-terminal da proteína N por RT-PCR, as sequências completas do gene H destas amostras foram diretamente amplificadas por RT-PCR a partir das amostras clínicas e posteriormente sequenciado.As análises filogenéticas da sequência de nucleotídeos do gene N e do gene H completomos traram que os vírus do sarampo genótipo D4 detectados no Brasil podem ser resultado de várias importações de diferentes variantes do mesmo genótipo que circulam na Europa. Foram identificadas mutações nas sequências de aminoácidos tantodo gene N parcial como do gene H completo dos genótipos D4 dos vírus do sarampo detectados no Brasil...

Measles is a highly infectious viral exanthem of the family Paramyxoviridae, genusMorbillivirus. Despite the availability of a safe and effective vaccine, measles infectioncontinues to be an important cause of infantile morbidity and mortality in developingcountries. Although there is only one antigenic type of the measles virus, geneticcharacterisation of the wild-type virus identified 8 subtypes (A-H), with a total of 24genotypes being recognised. From 2000, the indigenous transmission of the measlesvirus has been eliminated in Brazil. Since then, several cases of imported measles, orcases associated with importations, were confirmed, principally of genotype D4. Themolecular epidemiology of the measles virus based on analyses of the C-terminal regionof the nucleoprotein has demonstrated a limited diversity between circulating strains,making it difficult to determine the origin of the virus by this genomic region alone. Theobjective of this study was to genetically characterise the D4 genotype of measlesviruses detected in Brazil from 2003 to 2012 by analysing sequences from the completeH gene and partial N gene of the virus. Cases positive for measles genotype D4 werepreviously identified by the amplification of a 450nt of the C-terminal region of the Nprotein by RT-PCR. The complete H gene from these samples was amplified by RTPCRdirectly from clinical samples and subsequently sequenced. Phylogenetic analysisof the nucleotide sequences of the N gene and the complete H gene demonstrated thatthe measles D4 genotype detected in Brazil may have been a result of severalimportations of different variants of the same genotype circulating in Europe...