Mistaken for dengue, Zika cases may be underestimated
The methodologies currently available to the public health system, private labs and hospitals may also produce false positives for dengue in patients with Zika because the two viruses are so similar, said lead researcher Mauricio Lacerda Nogueira from Sao Jose do Rio Preto Medical School (FAMERP) in Sao Paulo, Brazil.
The team performed molecular tests on blood samples from 800 people treated as suspected dengue patients at the emergency facility of Hospital de Base, Sao Jose do Rio Preto’s reference hospital, between January and August 2016. The initial diagnosis, based on clinical symptoms and serological tests, was confirmed in only 400 samples.
More than 100 of the cases analysed were positive for Zika virus, and the virus that causes chikungunya fever was identified in one of the samples.
“These results suggest the classic division usually made between symptoms –associating conjunctivitis with Zika and joint pain with chikungunya, for example – is only for classroom use. In practice, the symptoms can’t be separated like that,” Nogueira said.
“It’s also practically impossible to distinguish between the three arboviruses with the serological tests currently used on a routine basis by laboratories and emergency services,” Nogueira noted.
Although new serological methods capable of distinguishing accurately between Zika and dengue antibodies have been developed, so far they are used only in academic research, he added in the study published in the Journal of Clinical Virology.
The World Health Organisation (WHO) recommends that all cases with an uncertain diagnosis should be treated as dengue because the risk of death from dengue is higher than from Zika and chikungunya.
False-positive results for dengue do not jeopardise treatment of patients but generate unnecessary costs for the health service, according to Nogueira.
“Rest and oral rehydration at home is usually sufficient for people with Zika, except pregnant women,” he said. “A dengue patient, however, must return to the health service for intravenous rehydration and undergo more complex tests. In particular, platelet levels have to be monitored owing to the risk of hemorrhage,” Nogueira said.
13 Indians test positive for Zika virus in Singapore, first pregnant woman diagnosed
Thirteen Indians have been infected with the Zika virus in Singapore, the Indian Ministry of External Affairs confirmed on Thursday. The patients have been admitted to hospitals, the MEA said. Identities of the patients have not been revealed.
Earlier in the day, Singapore’s Ministry of Health (MOH) confirmed that foreigners account for 57 of 115 Zika cases in Singapore so far, including 23 from China’s mainland and one from Taiwan, state-run Xinhua news agency reported. It added that all of the 57 foreigners who tested positive to Zika in Singapore had “mild illness” and most of them have recovered.
Meanwhile, Singapore confirmed its first case of a pregnant woman testing positive for the Zika virus infection. The Ministry of Health and National Environment Agency (NEA) said the woman was living in the virus-hit housing and industrial area of Sims Drive/Aljunied Crescent in the southeast of the island.
The woman, who displayed mild symptoms of the virus, was taken to KK Women’s and Children’s Hospital on Wednesday. A member of her house was also diagnosed as positive for Zika. Her doctor is following up closely with her to monitor her and her baby’s health, authorities said.
The NEA said it would begin mosquito control operations at the cluster involving three previously reported cases. “Our efforts will extend to other parts of Singapore,” the NEA said, adding that it will be stepping up its vector-control efforts to wider areas.
Malaysia reports first case
Malaysia’s Health Ministry has said a woman, who traveled to Singapore has been diagnosed with the Zika virus, the country’s first such case. The ministry says the 58-year-old woman tested positive for Zika a week after her return from Singapore. It says her daughter in Singapore also tested positive for Zika. It said the virus was believed imported from Singapore since the woman started experiencing symptoms on the same day as her daughter.