Chikungunya – Chad: Outbreak Information September 24, 2020 – Chad

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From July to September 20, 2020, a total of 27,540 cases were reported in three provinces, distributed as follows: 24,302 cases in Abéché Health District, 3,237 cases in Biltine Health District and one case in Abdi Health District. One death has so far been reported in the Abéché district. After a few hours of treatment in a health facility, patients continue on outpatient treatment. The most affected age group are people aged 15 and over. More than three quarters of the cases developed high fever, headache, and joint pain, while one third developed maculopapular rashes.

In July 2020, health officials were made aware of the occurrence of a disease-causing high fever, headache, intense and debilitating joint pain that was sometimes associated with vomiting. It was finally found to be Chikungunya virus after it was confirmed in a 63-year-old woman farmer. She had not reported any trip outside the Abéché district. A total of 12 samples from the Abéché district in Ouaddai province were sent to N’Djamena’s mobile laboratory for analysis on August 12, 2020, and 11 samples tested positive for Chikungunya virus.

The test results were confirmed by the Pasteur laboratory in Yaoundé, Cameroon (a WHO reference laboratory). Five samples were sent for quality control and found positive for Chikungunya virus by reverse transcriptase polymerase chain reaction (RT-PCR). The samples were also tested for other arboviruses (dengue and Zika), but not for O’nyong-Nyong virus or yellow fever virus.

In terms of vectors and the environmental context, Aedes mosquitoes have been found in the Abéché district to transmit the disease. The dry season should start in October with a hot, semi-arid climate that is less favorable for mosquitoes. Further entomological studies are underway in Wadi-Fira and Sila provinces to determine the presence of the vector responsible for the disease.

Abéché is the fourth largest city in Chad and the hub for the provision of humanitarian aid to around 240,000 Zulu refugees living in 12 camps east of the city in the border region of Sudan.

Public Health Response

  • Teams from the Ministry of Health and National Solidarity, WHO, the Red Cross and the local community are currently being deployed to destroy disinfection and larval breeding sites and run awareness campaigns in the provinces with cases.
  • A response plan is currently being validated with support from WHO and the health cluster partners.
  • Several coordination meetings were held including: national epidemic control coordination; and three sessions under the direction of the Provincial Health Delegate: The Ouaddai Provincial Committee; the – Wadi-Fira Provincial Committee; and the Provincial Committee of Sila;
  • Delivery of medicines and consumables to strengthen medical care;
  • Case investigation and active case finding in health structures and in households;
  • Collection, analysis and daily transmission of data and preparation of a management report;
  • Raising community awareness of disease prevention in the Abougoudam department;
  • Awareness of the population through community relays via radio channels;
  • Continuation of free treatment for patients in health structures;
  • The disinsection of all vehicles and transport buses on the Abéché-N’Djaména axis and other transport vehicles on the Abéché-Oum Hadjer axis is processed daily.
  • Fumigation disinsection operations carried out with the support of the local municipality of Abéché. Some challenges remain: vector control, social mobilization and risk communication

WHO risk assessment

Chikungunya is an arboviral disease that is transmitted to humans through the bites of infected Aedes mosquitoes. The disease is characterized by a sudden onset of fever, often accompanied by joint pain and inflammation, which are often very debilitating and can last for months or even years. Infection-related deaths can occur but are usually rare and most commonly reported in older adults with underlying disease or infants infected perinatally. Some patients may have rheumatoid symptoms (e.g., polyarthralgia, polyarthritis, and tenosynovitis) relapse in the months following the acute illness.

There is no specific antiviral treatment or commercially available vaccine for chikungunya. Chikungunya virus can cause large outbreaks with high attack rates, affecting one-third to three-quarters of the population in areas where the virus circulates, and therefore potentially overloading the health sector. The risk at the national level is moderate as many cases have been reported in a short period of time, Aedes vectors are present in the country and this is the first outbreak in the country. In the past, in other parts of the world, the virus has been shown to have strong epidemic potential in those regions where the population is naive to the Chikungunya virus. With the dry season approaching in early October with a hot, semi-arid climate less favorable for mosquito spreading, the risk is lower at the regional and global levels. Given the added burden of the COVID-19 pandemic on health system and health workers, there is a risk of disruption to access to health care. There may also be lower demand due to physical distancing requirements or community reluctance. In the current context, the ability of local laboratories and national reference laboratories to process samples (due to the high demand for processing COVID-19 samples) and a further increase in the number of cases likely to arise could potentially result in a significant burden on health care systems . Chad had 1,090 confirmed cases of COVID-19 with 81 deaths from March 19 to September 16, 2020.

WHO Council

It is recommended to use clothing that minimizes skin exposure to the day bite vectors. Repellents can be applied to exposed skin or clothing, strictly following the directions on the product label. Repellants should contain DEET (N, N-Diethyl-3-methylbenzamide), IR3535 (3-)[N-acetyl-N-butyl]Ethyl aminopropionate) or icaridine (1-piperidinecarboxylic acid, 2- (2-hydroxyethyl) -1-methylpropyl ester). Sleep under a mosquito net (during the day) and use air conditioning or window bars to avoid mosquito bites. Mosquito coils or other insecticide vaporizers can also reduce biting indoors.

The Aedes albopictus species thrives in a variety of water-filled containers, including tree holes and rock pools, as well as man-made containers such as unused vehicle tires, saucers under plant pots, rainwater barrels, cisterns, and catch basins. Aedes aegypti also breeds in artificial water tanks in and around houses and workplaces. Prevention and control depend heavily on reducing the number of these natural and man-made water-filled container habitats that aid mosquito breeding. This will require mobilizing affected communities, strengthening entomological surveillance to assess the impact of control measures, and implementing additional controls as needed. In the event of outbreaks, indoor spraying of flying mosquitoes with insecticides, measures to reduce sources and larvicides to kill the immature larvae can be used. National blood services / authorities should monitor epidemiological information and strengthen hemovigilance to identify possible transfusion transmission of Chikungunya virus. Based on the epidemiological situation and the risk assessment1, appropriate safeguards should be in place, consistent with the measures taken to prevent other transfusion-borne mosquito-borne viruses.

Other activities include: disseminating clinical guidelines for chikungunya, including key messages; Updated Clinician Training on Chikungunya Clinical Diagnosis; Case reporting; and case management during the acute phase, the subacute, chronic phase and in the event of complications. Ensuring free access to treatment and avoiding self-medication are also important measures.

1 http: //www.who.int/bloodsafety/publications/guide_selection_assessing_su …

2 Int. J. Environ. Res. Public Health 2018, 15, 220; doi: 10.3390 / ijerph15020220

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