Chikungunya cases surge sixfold in South China city in a week

A sudden surge of chikungunya cases has been reported in Foshan city in China, increasing from 478 cases to almost 3000 cases within a week, according to South China Morning Post.

France has reported over 53,000 cases in its overseas territories this year, reflecting a wider outbreak trend. Italian officials last week reported two deaths following 32 cases of West Nile virus, another mosquito-borne disease. Transmission dynamics are complicated by mosquitoes' ability to carry multiple viruses simultaneously.

For complex infections that may involve multiple viruses and pathogens, metagenomics next-generation sequencing (mNGS) technology is a more comprehensive approach. It offers in-depth reports for rapid and accurate detection. BGI Genomics PMseq™, using mNGS technology, supports global efforts in the diagnosis of complex infectious cases and tailors effective treatment.

Rapidly Expanding Global Threat

The World Health Organisation (WHO) recently warned of expanding chikungunya outbreaks, with cases spreading from Indian Ocean islands to several African nations like Madagascar, Somalia, and Kenya.

"Just like 20 years ago, the virus is now spreading further to other countries," said Dr Diana Rojas Alvarez, WHO lead on arboviruses, in a warning that underscores the virus's cyclical resurgence.

Among the hardest-hit is the French overseas territory of Réunion, where more than 53,000 cases have been confirmed this year. The island, home to under a million people, has seen approximately two-thirds of its population infected within a year, with hospitals recording nearly 600 admissions and 28 deaths.

China is also facing its most significant chikungunya outbreak since the virus first emerged there almost two decades ago. In Guangdong Province alone, around 4,800 cases were reported in just one month—3,000 of them concentrated within a single explosive week.

imported Cases to Locally Acquired

Chikungunya virus transmission occurs in a human-mosquito-human transmission cycle. This pattern of transmission, both imported and locally acquired cases, complicates the containment strategy.

Imported cases occur when individuals contract the virus while traveling in endemic regions and later fall ill back home. Domestic mosquito vectors can facilitate locally acquired infections and spread the virus locally once it arrives.

To combat mosquito-borne diseases at the community level, residents should regularly remove stagnant water and clear debris to destroy breeding grounds, while also using personal and home protection measures to prevent bites.

Anyone experiencing symptoms like fever, rash, or joint pain should seek immediate medical attention and report their travel history and any mosquito bites to healthcare providers. Early detection allows for timely intervention before symptoms progress to severe stages.

Genomics Unmask infectious Origin 

Chikungunya symptoms—fever, joint pain, and fatigue—are notoriously similar to those caused by other mosquito-borne viruses like dengue and Zika. This clinical overlap makes timely diagnosis difficult, especially in areas where multiple arboviruses are circulating simultaneously.

To address this challenge, many regions now employ reverse transcription polymerase chain reaction (RT-PCR) test kits, which are effective in detecting known viral genomes with high specificity. It identifies the virus' genetic material with high sensitivity and specificity. These PCR tests work best within the first 8 days of infection, when viral RNA is still present in the blood. RT-PCR provides fast, accurate results by targeting specific viral genomes.

For broader pathogen coverage, targeted next-generation sequencing (tNGS) technology offers broader detection capacity, along with high sensitivity and high specificity. It allows clinicians to pinpoint known infections and detect hundreds of unexpected pathogens within the target library.

Complex co-infections with unclear pathogens require more comprehensive testing. BGI Genomics PMseq™ Pathogen Metagenomics Sequencing, supported by metagenomics next-generation sequencing technology, can provide comprehensive and in-depth reports for rapid and accurate detection of difficult- and critical-to-detect infections.

The mNGS technology operates by extracting all nucleic acids from the clinical samples, performing high-throughput sequencing, and comparing the resulting sequences against a specialized pathogen database. The PMseq detects over 36,000 pathogens such as bacteria, fungi, viruses, parasites, etc., significantly improving the positive rate of pathogen detection.

Genetic Tools for Disease Prevention

Beyond diagnostics, scientists are exploring genomic solutions to halt mosquito-borne diseases at their source. A team of researchers recently made headlines after tweaking the genome of malaria-carrying mosquitoes. They disrupted the parasite's ability to complete its life cycle by altering a single amino acid, making the modified mosquitoes largely incapable of transmitting malaria. Published in Nature at the end of July, the study demonstrated how gene editing, and particularly gene drives, could revolutionize disease control.

Gene drives operate by skewing genetic inheritance. Instead of the standard 50% chance of passing on a gene, the altered trait is inherited by nearly all offspring. Though chikungunya differs from malaria in its viral nature, the gene-editing approach may hold promise for other mosquito-borne illnesses.

The fight against chikungunya and other mosquito-borne diseases requires an integrated approach. It requires close surveillance, rapid diagnostics, targeted treatment strategies, and forward-looking genetic technologies. As outbreaks grow worldwide, early detection and precise diagnosis will be key to infectious threats in this rapidly changing world.

About BGI Genomics PMseq™ Pathogen Metagenomics Sequencing

PMseq™ uses mNGS to extract nucleic acids from clinical infection samples after performing pre-processing, followed by sequencing on a high-throughput platform. By comparing the results against the specialized clinical database PMDB and utilizing advanced bioinformatic algorithms, PMseq™ can efficiently identify potential pathogens. This method enables unbiased detection of bacteria, fungi, viruses, parasites, and other pathogens, as well as the assessment of drug resistance and virulence genes. As a result, it significantly enhances the accuracy of pathogen diagnosis and helps guide the targeted use of antibiotics, making infection diagnosis and treatment more precise.

About BGI Genomics

BGI Genomics, headquartered in Shenzhen, China, is the world's leading integrated solutions provider of precision medicine. Our services cover more than 100 countries and regions, involving more than 2,300 medical institutions. In July 2017, as a subsidiary of BGI Group, BGI Genomics (300676.SZ) was officially listed on the Shenzhen Stock Exchange.