WHO | Chikungunya – Chad

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

In July 2020, health authorities were warned of the occurrence of high fever causing illness, headaches, intense and disabling joint pain, and sometimes associated with vomiting. It was eventually determined that it was the chikungunya virus after it was confirmed in a 63-year-old jeans woman. She did not report a trip outside Abéché County. A total of 13 samples from Abéché County, Ouaddai Province, were sent for analysis to the N’Djamena Mobile Laboratory on August 12, 2020, and 11 samples were positively tested for chikungunya virus.

The test results were confirmed by the Pasteur Laboratory in Yaoundé, Cameroon (WHO reference laboratory), with five samples sent for quality control determined positive for chikungunya virus by reverse transcriptase-polymerase chain reaction (RT-PCR). 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 environmental context, Aedes mosquitoes that transmit the disease are found in the district of Abéché. The dry season should start in October with a hot semi-arid climate, unfavorable for mosquitoes. Other entomological studies are underway in Wadi-Fira and Sila provinces to determine the presence of a vector responsible for the disease.

Abéché is the fourth largest city in Chad and is the center of humanitarian aid delivery for approximately 240,000 Darfur refugees living in 12 campsites east of the city, in the border region of Sudan.

Public health response

• Teams from the Ministry of Health and National Solidarity, the WHO, the Red Cross and the local municipality are currently deployed to carry out cases of disinfection and destruction of larval breeding sites in the provinces and conduct awareness-raising campaigns;
• The response plan is currently being confirmed with the support of the WHO and the Health Cluster partner;
• Several coordination meetings were held, including: national coordination to combat epidemics; and three meetings chaired by the Provincial Health Delegate: Ouaddai Provincial Committee; Wadi-Fira Provincial Committee; and the Provincial Board of Forces;
• Delivery of medicines and consumables to enhance medical care;
• Case investigation and active case finding in health structures and in households;
• Collection, analysis and daily transmission of data and preparation of situation reports;
• Community awareness of disease prevention implemented in the Abougoudam department;
• Sensitization of the population via community relays via radio channels;
• Continuation of free treatment for patients in health facilities;
• Disinsection of all vehicles and transport buses on the Abéché-N’Djaména axis and other transport vehicles on the Abéché-Oum Hadjer axis are treated daily;
• Fumigation disinsection operations carried out with the support of the local municipality of Abéché
• Some challenges remain: vector control, social mobilization, and communication with risk

WHO risk assessment

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

There is no specific antiviral treatment or commercially available vaccine for chikungunya. Chikungunya virus can cause large epidemics with a high rate of attack, affecting one-third to three-quarters of the population in areas where the virus circulates, potentially leading to health sector overload. The risk at the national level is moderate due to the large number of cases reported in a short period of time, the presence Aedes vectors in the country and the fact that this is the first outbreak in the country. In other parts of the world, the virus has been shown in the past to have strong epidemic potential in regions where the population is naive to the chikungunya virus. As the dry season approaches in early October with a hot semi-arid climate less conducive to mosquito spread, the risk is lower regionally and globally. With the additional burden of the COVID-19 pandemic on the health system and health workers, there is a risk of disrupting access to health care. Demand may also be reduced due to requests for physical distancing or community reluctance. In the current context, the capacity of local laboratories and national reference laboratories to process samples (due to the high demand for COVID-19 sample processing) and the further increase in the number of cases that could occur could potentially lead to a significant burden on health services. From March 19 to September 16, 2020, 1,090 confirmed cases of COVID-19 with 81 deaths were recorded in Chad.

WHO advice

Clothing that minimizes skin exposure to daily vectors is recommended. Repellents can be applied to exposed skin or clothing, strictly following the instructions on the product label. Repellents should contain DEET (N, N-diethyl-3-methylbenzamide), IR3535 (3-[N-acetyl-N-butyl]-aminopropionic acid ethyl ester) or icaridine (1-piperidinecarboxylic acid, 2- (2-hydroxyethyl) -1-methylpropyl ester). Sleep under a mosquito net (during the day) and use air conditioners or window screens to prevent mosquito bites. Mosquito coils or other insecticide vaporizers can also reduce indoor biting.

The Aedes albopictus the species thrives in a wide range of water-filled containers, including tree holes and rock pools, with artificial containers such as unused vehicle tires, saucers under plant containers, rainwater barrels, cisterns, and catch pools. Aedes aegypti it also breeds in artificial water that holds containers in and around houses and workplaces. Prevention and control rely heavily on reducing the number of these natural and artificial water-filled habitats, which support mosquito breeding. This requires mobilizing affected communities, strengthening entomological monitoring to assess the impact of control measures, and implementing additional controls as needed. During an outbreak, internal insecticide spraying can be used to kill flying mosquitoes, along with source reduction measures, and larvicides to kill immature larvae. National blood services / authorities should monitor epidemiological information and strengthen haemovigilance to identify any potential transfusion-transmission of chikungunya virus. Based on the epidemiological situation and the risk assessment, appropriate safety precautions should be taken in accordance with the measures taken to prevent other transfusion-transmitted viruses.¹.

Further activities include: disseminating chikungunya clinical guidelines, including key messages; updated training for clinicians on the clinical diagnosis of chikungunya; case reporting; and case management during the acute phase, subacute, chronic phase and when there are complications. Ensuring free access to treatments and avoiding self-medication are also important actions.

¹ http://www.who.int/bloodsafety/publications/guide_selection_assessing_suitable.pdf

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

For more information: