Sciency Thoughts: Epidemeology

Showing posts with label Epidemeology. Show all posts

Tuesday, 3 September 2024

Outbreak of Chandipura Virus causes at least 82 deaths in India.

Between 1 June and 15 August 2024, the Indian Ministry of Health and Family Welfare recorded 245 cases of suspected Chandipura Virus infection in Gujarat and Rajasthan states, with 45 districts affected and 82 known deaths, a case fatality rate of 33%, according to a press release issued by the World Health Organization on 23 August 2024. Sixty four of the cases have been confirmed as Chandipura Virus by either immunoglobulin M enzyme-linked immunosorbent assay or reverse transcription polymerase chain reaction, sixty one of these in Gujarat and three in Rajasthan. The number of new cases being reported has been declining since 19 July 2024.

Chandipura Virus, or Chandipura vesiculovirus, is endemic to western, central, and southern India, with sporadic outbreaks occurring across this region, typically during the monsoon season. In 2023 an outbreak of the Virus in Andhra Pradesh led to 183 deaths among 329 reported cases, a case fatality rate of 55.6%. Other recent outbreaks have led to case fatality rates of between 56 and 75%. In Gujarat there appears to be a spike in cases every four-to-five years.

Chandipura vesiculovirus is a negative-sense single-stranded RNA Virus in the family Rhabdoviridae. Like many Viruses in this family, it is a zoonotic disease which can be spread by a number of Arthropod vectors, including Sandflies, Mosquitoes, and Ticks, although its main vector appears to be the Sandfly, Phlebotomus papatasi. Notably, although Human infections with Chandipura vesiculovirus have been reported only from India, the Sandfly, Phlebotomus papatasi, has a much wider distribution, and the Virus has been extracted from Sandflies in Senegal, as well as a range of Mammals in Senegal, Nigeria, Bhutan, and Nepal, suggesting a much wider, undetected, range.

Transmission electron micrographs of primary Chandipura Virus isolates from culture. Rao et al. (2004).

Chandipura Virus infection can lead to the development of a febrile disease, predominantly in children under 15, which can lead rapidly to convulsions, coma, and in the worst cases, death. In children, where fatality occurs, it typically happens within 48-72 hours of the first symptoms being detected.

The Indian Ministry of Health and Social Welfare has deployed specialist teams to Gujarat State to help implement control measures, including fumigating dwellings with insecticide to control the vectors of the disease and an education campaign aimed at raising awareness of the Virus, symptoms, and preventive measures.

Friday, 25 December 2020

Outbreak of Yellow Fever reported in Guinea.

The World Health Organisation has reported an outbreak of Yellow Fever in Guinea, with 52 suspected cases of the disease reported between 6 November and 15 December 2020, fourteen of which subsequently died. Fifty of the reported cases are from the Koundara Health District, one from the Dubreka Health District, and one from the Kouroussa Health District. Tests carried out at the Nongo Laboratory of Viral Haemorrhagic Fevers in Conakry confirmed Yellow Fever in eight of the patients from Koundara, plus both the Debreka and Kouroussa patients. Further tests carried out at the Institut Pasteur de Dakar confirmed Yellow Fever in eight Koundara patients.

Geographic distribution of suspected and confirmed cases of yellow fever per 100,000 inhabitants by sub-prefecture, in the health district of Koundara, 30 November 2020. World Health Organisation.

Yellow Fever is a Mosquito-borne Flavivirus (the group of RNA Viruses that also includes the West Nile, Zika and Hepatitis C Viruses). The Virus causes a mild fever, accompanied loss of appatite, nausea and muscle pains, which passes within about 15 days. However, in about 15 % of cases a more severe infection attacks the liver and kidneys, which can lead to their failure, and therefore the death of the patient. It originated in tropical Africa and but was carried to South America and the Caribbean during the trans-Atlantic slave trade. Outbreaks of the disease have also been recorded in parts of tropical Asia and the Pacific in recent years, and many countries in tropical regions require visitors to carry a certificate proving they have been vaccinated against the Virus.

The Yellow Fever Virus. Erskine Palmer/Centers for Disease Control and Prevention/Wikipedia.

Guinea is considered to be a high-risk endemic country for Yellow Fever, and is carrying out a national program of vaccinations, as well as requiring all visitors to the country aged nine months or above to be vaccinated. However, it is currently estimated that only about 40% of the population has been vaccinated to date, with vaccination rates particularly low in the Koundara Health District where only about 16% of the population has been reached; all of confirmed Yellow Fever cases from Koundara were from patients that had not been vaccinated.

Friday, 4 December 2020

Burkina Faso hit by outbreak of Hepatitis E.

The West African nation of Burkina Faso has been hit by an outbreak of febrile jaundice (fever combined with yellowing of the skin), with 442 cases and sixteen deaths reported between 8 September and 25 November 2020, the majority of the cases (387) in the Barsalogho Health District. Polymerase chain reaction tests carried out on samples taken from 10 of the patients have produced positive results for Hepatitis E, with none testing positive for any other causative agent for such fevers, such as Malaria, Leptospirosis or other forms of Hepatitis, nor have they tested positive for Covid 19, a disease which is currently running epidemic in Burkina Faso, with 2757 cases and 68 deaths reported so far this year. The majority of patients reporting symptoms (68%) are under 30, with an average age of 25, and 54% of the patients are female. Fifteen of the sixteen fatalities were women who were either pregnant or had recently given birth, which is typical of Hepatitis E, which is considered to be particularly dangerous to pregnant women.

Reported cases of febrile jaundice in the North-central Region of Burkina Faso in 2020 to 24 November. World Health Organisation.

Hepatitis E is caused by a single-stranded, nonenveloped, RNA Virus, and is usually a self-limiting infection, causing fever, nausea, loss of appetite, vomiting, jaundice, abdominal and joint pain and discolouration of the urine and stool, which typically passes within 2-6 weeks. However, in some cases the disease can cause acute liver failure (hepatitis) which is often fatal. Pregnant women are considered to be at particular risk from this disease, with a fatality rate of about 30%, compared to about 1% for the general population.

The Hepatitis E Virus. Centers for Disease Control and Prevention/Wikipedia.

Hepatitis E is spread through faeces and contaminated water, and thrives in unsanitary and crowded conditions. This was become a problem in Burkina Faso since September 2017, when an armed conflict broke out in the country, which has displaced many people internally, with people moving away from their traditional farmlands into lager towns where they receive some protection from the nation's security services, but resulting in many people living in overcrowded conditions with poor sanitation.