Cross-border collaboration between China and Myanmar for emergency response to imported vaccine derived poliovirus case

Background

This report describes emergency response following an imported vaccine derived poliovirus (VDPV) case from Myanmar to Yunnan Province, China and the cross-border collaboration between China and Myanmar. Immediately after confirmation of the VDPV case, China disseminated related information to Myanmar with the assistance of the World Health Organization.

Methods

A series of epidemiological investigations were conducted, both in China and Myanmar, including retrospective searches of acute flaccid paralysis (AFP) cases, oral poliovirus vaccine (OPV) coverage assessment, and investigation of contacts and healthy children.

Results

All children <2 years of age had not been vaccinated in the village where the VDPV case had lived in the past 2 years. Moreover, most areas were not covered for routine immunization in this township due to vaccine shortages and lack of operational funds for the past 2 years.

Conclusions

Cross-border collaboration may have prevented a potential outbreak of VDPV in Myanmar. It is necessary to reinforce cross-border collaboration with neighboring countries in order to maximize the leverage of limited resources.

[Molecular epidemiological analysis of ECHO7 virus isolated from sewage water in Yunnan Province, China]

To investigate the epidemic and evolutionary trends of enterovirus (EV) in the external environment of Yunnan Province, China, molecular typing was performed on 4 EV strains that were isolated from environmental sewage in Yunnan. The VP1 region of isolates was amplified by RT-PCR using universal enterovirus primers, and the amplified VP1 region was sequenced for GenBank BLAST search and genotype analysis. The 4 EV strains were identified as ECHO7. Their nucleotide and amino acid homologies with the VP1 sequences of 68 ECHO7 strains retrieved from GenBank were measured by Mega software analysis. Our findings showed that ECHO7 strains from environmental sewage and population samples were in different evolutionary branches. These strains showed typical geographical and temporal differences; In addition, there were different transmission chains at the same time and in the same area. ECHO7 strains isolated from sewage water and patients with acute flaccid paralysis during the same period in Yunnan belonged to different clusters and evolved at different speeds. Special concerns are needed for this problem. Continuous molecular biological surveillance of human EV in the external environment of Yunnan will provide strong support for early warning of EV diseases.

[Study on the molecular typing and epidemiology of non-polio enterovirus in Yunnan Province, China during 2006-2010]

In order to explore the genotype distribution and molecular evolution of non-polio enterovirus (NPEVs)in Yunnan Province,the People's Republic of China, we sequenced and analyzed the partial VP1 coding region of 105 NPEVs isolated from acute flaccid paralysis (AFP) surveillance in Yunnan province during a 5- year study period from 2006 to 2010. The viral genomes of 105 NPEVs were translated to corresponding amino acid sequences and compared with those of the prototype strains, and the phylogenetic tree was constructed among these VP1 nucleotide sequences and other prototype strains from GenBank. Analysis showed that 18 isolates were classified into 7 serotypes of human enterovirus A species, while 77 isolates into 22 serotypes of B and 10 isolates into 4 serotypes of C species. However, we did not isolate any viruses which belonged to human enterovirus D species. Thus, under AFP surveillance, human enterovirus B species accounted for 73. 3% of the 105 isolates and was considered as the predominant one,followed by human enterovirus A(17. 1%) and human enterovirus C(9. 5%). Phylogenetic analysis showed that various serotypes of the virus and the corresponding prototype strains or other representative strains clustered into the same grooup, however, Yunnan strains and prototype strains were located in the different branches (except CA2,EV90 and EV76). The degree of variation was different even among the same genotype strains. This report showed that different genotype strains spread widely in Yunnan Province.

[Molecular typing of enteroviruses from healthy children in the border areas of Yunnan Province and Myanmar and the genetic characteristics of ECHO7 and ECHO13 in 2009]

To explore the enteroviruses surveillance among healthy children under 15 years old in the border areas of Yunnan Province and Myanmar in 2009. The stool samples were collected from the healthy children under 15 years old who came from the border areas of Myanmar and Yunnan Province, virus isolation and sequencing were conducted for all the 271 samples. 6 strains of polioviruses (PVs) were detected from 271 stools with an isolation rate of 2.8%, which belonged to vaccine strains and 24 non-polioviruses (NPVs) were detected with an isolation rate of 8.9%. 24 NPVs belonged to human enterovirus group B (HEV-B) with 6 serotypes, HEV-A, HEV-C and HEV-D viruses were not isolated. Among them, 13 NPVs were E7 (54.17%) and 5 NPVs were E13 (20.83%). Our results showed that the enterovirus carrying rate in the border areas of Yunnan province was higher than the rate of routine acute flaccid paralysis (AFP) detection system. The HEV-B viruses were the only enteroviruses isolated. The phylogenetical analysis showed that Echovirus 7(E7) and 13 (E13) exhibited genetic polymorphism.

[Molecular identification of hepatitis B virus genotype I in Yunnan Province, the People's Republic of China]

Molecular typing was conducted according to the reported method for one HBsAg positive carrier who had a physical examination in Yunnan Province. The S gene of this HBV sample was amplified by nested PCR and the PCR products were directly sequenced. Blast searching was done on the Genbank database and the sequence were compared with the HBV reference sequences in database. The phylogenetic tree was constructed. Homology analysis of nucleotide and smino acid were performed between the sequences from the sample and the reference sequences corresponding to HBV genotype A to I. Analysis of nucleotide and amino acid identities suggested that the sample belonged to HBV genotype I. The HBV genotype I is the first reported in China.

[Investigation on one vaccine-derived poliovirus (VDPV) case in Yunnan Province]

To find out epidemiological feature of paralytic cases caused by type 2 vaccine-derived poliovirus (VDPV) and the excretion status of the case and to explore the enterovirus infection status among healthy children under five years old around the case in Zhaotong city, Yunnan Province in 2010. Field epidemiological studies at the epidemic area were conducted and a total of 108 stool samples were collected, three from the case, seven from the close contacts and 98 from the healthy children. VDPV was not isolated again from the case; Sabin-like PV strains or VDPV were not isolated from the close contacts and the healthy children; An active search for acute flaccid paralysis cases was conducted in the area, which indicated that the VDPV did not cause virus circulation in local area. Twenty one (20.0%) NPEVs were isolated from 105 stool samples. Among the 21 NPEV isolates, 11 isolates (52.4%) were HEV-A (3 serotypes), 10 isolates (47.6%) were HEV-B (4 serotypes).

[Molecular identification of human enterovirus 73 in Yunnan Province, the People's Republic of China]

Molecular typing was conducted according to the reported methods for 2 enteroviruses that were isolated from healthy children in the border areas of Yunnan Province with Myanmar. RT-PCR and sequencing were performed with 292/222 primers according to the Oberste's methods. The resulting sequences were blasted against the Genbank database and compared with all available enterovirus database. Analysis of homology at nucleotide and amino acid level identically suggested that the two enteroviruses are human enterovirus 73.

[Study on the influencing factors of hepatitis B vaccine timely birth dose for infants born at hospitals]

OBJECTIVE

To study the coverage of timely birth dose of HepB vaccine (HepB1) and reasons contributed to the non-timely of HepB1 for the infants delivered in the hospital of remote and poverty areas in Yunnan province, and to bring forword the special strategies to improve the coverage of HepB of infants born at those hospitals.

METHODS

According to the reported coverage and the estimated coverage of HepB1 vaccine, the HepB coverage of infants born at hospitals was investigated by sampling in Zhaotong and Xishuangbanna in 2007.

RESULTS

The average coverage of HepB1 of infants born at the local hospitals was 67.19%, and the HepB1 coverage of infant was higher in county hospitals than in township hospitals. Infants with premature, low birth weight and asphyxia and the shortage of HepB vaccine were the mainly reasons to the non-timely HepB1 of infants born at hospitals.

CONCLUSION

The HepB1 coverage of infants was still keep at low level in the local hospital; and to assure enough HepB vaccine in the village hospitals and to grasp immunization contraindication correctly were the two key strategies to promote the HepB1 coverage for infants born at the local hospitals.

[Characteristics of 57 acute flaccid paralysis cases with polio-virus isolated from stool specimens, in Yunnan province, from 2003 to 2007]

OBJECTIVE

Study on the epidemiological characteristics of poliomyelitis virus in Yunnan, from 2003 to 2007.

METHODS

Surveillance data of acute flaccid paralysis (AFP) cases from year 2003 to 2007 was gathered. All the stool specimens were identified to contain polio virus.

RESULTS

1171 AFP cases were reported. Out of the total number of 1138 stool specimens from 2003 to 2007, 57 cases showed polio virus (5.0%), 159 showed NPEV (14.0%), 922 cases showed virus negative. In those virus, polio type II took the lead (31.6%). 57 AFP cases appeared in 37 (28.7%) counties in Yunnan. Most of the cases were under 2 years of age. 29 cases had taken more than 3 OPV (oral poliovaccine) dosages and 41 cases had fever before paralysis occurred. Most of the cases appeared paralysis on single lower limb, but 26 cases leaving deformity. Significant difference was found between the two groups: having received vaccination more than 3 OPV dosages or less than 3 dosages.

CONCLUSION

High quality AFP epidemiological and laboratory surveillance program, together with OPV routine and supplemental immunization strategy to cover the poorly immunized area/population appeared to be most effective.

[Analysis on immune effect of different measles vaccine among 196 infants at age of 8-month in Yunnan Province]

OBJECTIVE

To analyze the effect of different dosage of measles vaccines (0.2 ml or 0.5 ml) to measles antibody level in 8 month-old infants and study the relationship between maternal antibody in infants and the immune response to the vaccine.

METHODS

196 8 month-old infants and their mothers were selected randomly. The measles IgG-antibody in infants before and after vaccination and in their mothers was detected by ELISA.

RESULTS

Total 101 infants received 0.2 ml MV and 95 infants received 0.5 ml MV. (1) Among all infants who were antibody negative before vaccination, the immune success rate was 88.24% in the Group 1 and 97.3% in Group 2. There were significant differences between the 2 groups (chi2=4.656 P=0.031). (2) Infants who were antibody positive before vaccination the immune success rate was 56.25% in Group 1 and 57.14% in Group 2. There were no significant differences between the 2 groups (chi2=0.003 P=0.957). (3) Before receiving MV, the seronegative rate in total 196 infants was 81.12%, but the seronegative rate in their mothers was 7.65%.

CONCLUSION

For 8 month-old infants, the maternal antibody has limited influence on the immune success rate. Increasing the dosage to 0.5 ml could increase the success rate and decrease the primary immune failure among infants who were antibody negative pre-vaccination. However, for those infants who were antibody positive pre-vaccination, the antibody level was not increase along with the increasing of the vaccine dosage.

Induction of platelet activation by cobra venom factor from Naja naja atra in rat

AIM

To study the effects of cobra venom factor (CVF) on platelets of rat platelet rich plasma (PRP) and to elucidate its cellular mechanism.

METHODS

PRP was used to measure platelet aggregation and ATP-release simultaneously; prothrombinase, intracellular free calcium, and cAMP were assayed using chromogenic substrate, fluorophor Fura-2, and RIA respectively.

RESULTS

From 19.5 nmol.L-1 to 617 nmol.L-1 CVF induced platelet aggregation and ATP release concentration-dependently. The ATP release induced by CVF 195 nmol.L-1 was independent of aggregation and was much weaker than that induced by thrombin 1 U/ml. CVF 195 nmol.L-1 increased the prothrombinase activity on platelet surface in a time-dependent manner. SZ-1, SZ-21, and SZ-22, which are monoclonal antibodies against glycoproteins I b/IX, IIIa, and IIb located on platelet membranes, inhibited CVF-induced platelet aggregation. CVF 195 nmol.L-1 also elevated moderately intracellular free calcium ion from (141 +/- 46) to (240 +/- 64) nmol.L-1 in Fura-2 AM loaded platelets, and decreased intracellular cAMP.

CONCLUSION

Complement activator CVF induced platelet aggregation and ATP release, and increased prothrombinase activity on platelet surface. These actions were dependent on fibrinogen receptors on the platelet surface, elevation in intracellular free calcium ion, and reduction in cAMP.

Vertical transmission of human immunodeficiency virus type 1: frequency and correlation of transmission (review)

Child bearing age women constitute the fastest growing subset of the human immunodeficiency virus (HIV) infected population. Consistent with this fact is the increasing number of HIV infected children. Vertical transmission from mother to child is the most common route of infection. Because of the nature of the virus, it is difficult to determine the timing of infection. There are three time periods during which infection can occur: prenatally, perinatally, or postnatally. Evidence for each is presented within this review.